text:
Formal Logic/Predicate Logic/Models

= Models =

Interpretations
We said earlier that the formal semantics for a formal language such as $$\mathcal{L_S}\,\!$$ (and now $$\mathcal{L_P}\,\!$$) goes in two parts.

 * Rules for specifying an interpretation. An interpretation assigns semantic values to the non-logical symbols of a formal syntax.  Just as a valuation was an interpretation for a sentential language, a model is an interpretation for a predicate language.

 * Rules for assigning semantic values to larger expressions of the language. All formulae of the sentential language $$\mathcal{L_S}\,\!$$ are sentences.  This enabled rules for assigning truth values directly to larger formulae.  For the predicate language $$\mathcal{L_P}\,\!$$, the situation is more complex.  Not all formulae of $$\mathcal{L_P}\,\!$$ are sentences.  We will need to define the auxiliary notion satisfaction and use that when assigning truth values.

Models
A model is an interpretation for a predicate language. It consists of two parts: a domain and interpretation function. Along the way, we will progressively specify an example model $$\mathfrak{M}\,\!$$.

Domain

 * A domain is a non-empty set.

Intuitively, the domain contains all the objects under current consideration. It contains all of the objects over which the quantifiers range. $$\forall x\,\!$$ is then interpreted as 'for any object $$x\,\!$$ in the domain …'; $$\exists x\,\!$$ is interpreted as 'there exists at least one object $$x\,\!$$ in the domain such that …'. Our predicate logic requires that the domain be non-empty, i.e., that it contains at least one object.

The domain of our example model $$\mathfrak{M}\,\!$$, written $$|\mathfrak{M}|\,\!$$, is {0, 1, 2}.

Interpretation function

 * An interpretation function is an assignment of semantic value to each operation letter and predicate letter.

The interpretation function for model $$\mathfrak{M}\,\!$$ is $$I_{\mathfrak{M}}\,\!$$.

Operation letters

 * To each constant symbol (i.e., zero-place operation letter) is assigned a member of the domain.

Intuitively, the constant symbol names the object, a member of the domain. If the domain is $$|\mathfrak{M}|\,\!$$ above and $$a^0_0\,\!$$ is assigned 0, then we think of $$a^0_0\,\!$$ naming 0 just as the name 'Socrates' names the man Socrates or the numeral '0' names the number 0. The assignment of 0 to $$a^0_0\,\!$$ can be expressed as:

 * $$I_{\mathfrak{M}}(a^0_0) = 0\ .\,\!$$

 * To each n-place operation letter with n greater than zero is assigned an n+1 place function taking ordered n-tuples of objects (members of the domain) as its arguments and objects (members of the domain) as its values. The function must be defined on all n-tuples of members of the domain.

Suppose the domain is $$|\mathfrak{M}|\,\!$$ above and we have a 2-place operation letter $$f^2_0\,\!$$. The function assigned to $$f^2_0\,\!$$ must then be defined on each ordered pair from the domain. For example, it can be the function $$\mathfrak{f}^2_0\,\!$$ such that:

 * $$\mathfrak{f}^2_0(0, 0) = 2, \quad \mathfrak{f}^2_0(0, 1) = 1, \quad \mathfrak{f}^2_0(0, 2) = 0,\,\!$$
 * $$\mathfrak{f}^2_0(1, 0) = 1, \quad \mathfrak{f}^2_0(1, 1) = 0, \quad \mathfrak{f}^2_0(1, 2) = 2,\,\!$$
 * $$\mathfrak{f}^2_0(2, 0) = 0, \quad \mathfrak{f}^2_0(2, 1) = 2, \quad \mathfrak{f}^2_0(2, 2) = 1\ .\,\!$$

The assignment to the operation letter is written as:

 * $$I_{\mathfrak{M}}(f^2_0) = \mathfrak{f}^2_0\ .\,\!$$

Suppose that $$a^0_0\,\!$$ is assigned 0 as above and also that $$b^0_0\,\!$$ is assigned 1. Then we can intuitively think of the informally written $$f(a, b)\,\!$$ as naming (referring to, having the value) 1. This is analogous to 'the most famous student of Socrates' naming (or referring to) Plato or '2 + 3' naming (having the value) 5.

Predicate letters

 * To each sentence letter (i.e., zero-place predicate letter) is assigned a truth value. For $$\pi\,\!$$ a sentence letter, either

 * $$I_{\mathfrak{M}}(\pi) = \mathrm{True}\,\!$$

or

 * $$I_{\mathfrak{M}}(\pi) = \mathrm{False}\ .\,\!$$

This is the same treatment sentence letters received in sentential logic. Intuitively, the sentence is true or false accordingly as the sentence letter is assigned the value 'True' or 'False'.

 * To each n-place predicate letter with n greater than zero is assigned an n-place relation (a set of ordered n-tuples) of members of the domain.

Intuitively, the predicate is true of each n-tuple in the assigned set. Let the domain be $$|\mathfrak{M}|\,\!$$ above and assume the assignment

 * $$I_{\mathfrak{M}}(\mathrm{F^2_0})\ =\ \{\langle 0,\ 1\rangle,\ \langle 1,\ 2\rangle,\ \langle 2,\ 1\rangle\}.$$

Suppose that $$a^0_0\,\!$$ is assigned 0, $$b^0_0\,\!$$ is assigned 1, and $$c^0_0\,\!$$ is assigned 2. Then intuitively $$\mathrm{F}(a, b)\,\!$$, $$\mathrm{F}(b, c)\,\!$$, and $$\mathrm{F}(c, b)\,\!$$ should each be true. However, $$\mathrm{F}(a, c)\,\!$$, among others, should be false. This is analogous to 'is snub-nosed' being true of Socrates and 'is greater than' being true of $$\langle 2, 3\rangle$$.

Summary
The definition is interspersed with examples and so rather spread out. Here is a more compact summary. A model consists of two parts: a domain and interpretation function.

 * A domain is a non-empty set.

 * An interpretation function is an assignment of semantic value to each operation letter and predicate letter. This assignment proceeds as follows:

 * To each constant symbol (i.e., zero-place operation letter) is assigned a member of the domain.
 * To each n-place operation letter with n greater than zero is assigned an n+1 place function taking ordered n-tuples of objects (members of the domain) as its arguments and objects (members of the domain) as its values.
 * To each sentence letter (i.e., zero-place predicate letter) is assigned a truth value.
 * To each n-place predicate letter with n greater than zero is assigned an n-place relation (a set of ordered n-tuples) of members of the domain.

A finite model
An example model was specified in bits and pieces above. These pieces, collected together under the name $$\mathfrak{M}\,\!$$, are:

 * $$|\mathfrak{M}|\ =\ \{0,\ 1,\ 2\}\ .\,\!$$
 * $$I_{\mathfrak{M}}(a^0_0)\ =\ 0\ .\,\!$$
 * $$I_{\mathfrak{M}}(b^0_0)\ =\ 1\ .\,\!$$
 * $$I_{\mathfrak{M}}(c^0_0)\ =\ 2\ .\,\!$$
 * $$I_{\mathfrak{M}}(f^2_0)\ =\ \mathfrak{f}^2_0\ \mbox{such that:} \quad \mathfrak{f}^2_0(0, 0) = 2,\ \mathfrak{f}^2_0(0, 1)\ =\ 1,\ \mathfrak{f}^2_0(0, 2) = 0,\,\!$$
 * $$\mathfrak{f}^2_0(1, 0) = 1,\ \mathfrak{f}^2_0(1, 1)\ =\ 0,\ \mathfrak{f}^2_0(1, 2) = 2,\ \mathfrak{f}^2_0(2, 0) = 0,\,\!$$
 * $$\mathfrak{f}^2_0(2, 1) = 2,\ \mbox{and}\ \mathfrak{f}^2_0(2, 2) = 1\ .\,\!$$
 * $$I_{\mathfrak{M}}(\mathrm{F^2_0})\ =\ \{\langle 0,\ 1\rangle,\ \langle 1,\ 2\rangle,\ \langle 2,\ 1\rangle\}.$$

We have not yet defined the rules for generating the semantic values of larger expressions. However, we can see some simple results we want that definition to achieve. A few such results have already been described:

 * $$f(a, b)\ \mbox{resolves to}\ 1\ \mathrm{in}\ \mathfrak{M}\ .\,\!$$
 * $$\mathrm{F}(a, b),\ \mathrm{F}(b, c),\ \mbox{and}\ \mathrm{F}(c, b)\ \mbox{are True in}\ \mathfrak{M}\ .\,\!$$
 * $$\mathrm{F}(a, a)\ \mbox{is False in}\ \mathfrak{M}\ .\,\!$$

Some more desired results can be added:

 * $$\mathrm{F}(a, f(a, b))\ \mbox{is True in}\ \mathfrak{M}\ .\,\!$$
 * $$\mathrm{F}(f(a, b), a)\ \mbox{is False in}\ \mathfrak{M}\ .\,\!$$
 * $$\mathrm{F}(c, b) \rightarrow \mathrm{F}(a, b)\ \mbox{is True in}\ \mathfrak{M}\ .\,\!$$
 * $$\mathrm{F}(c, b) \rightarrow \mathrm{F}(b, a)\ \mbox{is False in}\ \mathfrak{M}\ .\,\!$$

We can temporarily pretend that the numerals '0', '1', and '2' are added to $$\mathcal{L_P}\,\!$$ and assign then the numbers 0, 1, and 2 respectively. We then want:

 * $$(1) \quad \mathrm{F}(0, 1) \rightarrow \mathrm{F}(1, 0) \quad \mbox{False in}\ \mathfrak{M}\ .\,\!$$
 * $$(2) \quad \mathrm{F}(1, 2) \land \mathrm{F}(2, 1) \quad \mbox{True in}\ \mathfrak{M}\ .\,\!$$

Because of (1), we will want as a result:

 * $$\forall x\, \forall y\, (\mathrm{F}(x, y) \rightarrow \mathrm{F}(y, x))\ \mbox{is false in }\ \mathfrak{M}\ .\,\!$$

Because of (2), we will want as a result:

 * $$\exists x\, \exists y\, (\mathrm{F}(x, y) \land \mathrm{F}(y, x))\ \mbox{is true in}\ \mathfrak{M}\ .\,\!$$

An infinite model
The domain $$|\mathfrak{M}|\,\!$$ had finitely many members; 3 to be exact. Domains can have infinitely many members. Below is an example model $$\mathfrak{M}_2\,\!$$ with an infinitely large domain.

The domain $$|\mathfrak{M}_2|\,\!$$ is the set of natural numbers:
 * $$|\mathfrak{M}_2| = \{0, 1, 2, ...\}\,\!$$

The assignments to individual constant symbols can be as before:
 * $$I_{\mathfrak{M}_2}(a^0_0)\ =\ 0\ .\,\!$$
 * $$I_{\mathfrak{M}_2}(b^0_0)\ =\ 1\ .\,\!$$
 * $$I_{\mathfrak{M}_2}(c^0_0)\ =\ 2\ .\,\!$$

The 2-place operation letter $$f\,\!$$ can be assigned, for example, the addition function:
 * $$I_{\mathfrak{M}_2}(f^2_0)\ =\ \mathfrak{f}^2_0\ \mbox{such that}\ \mathfrak{f}^2_0(u, v) = u + v\ .\,\!$$

The 2-place predicate letter $$\mathrm{F^2_0}\,\!$$ can be assigned, for example, the less than relation:
 * $$I_{\mathfrak{M}_2}(\mathrm{F^2_0})\ =\ \{\langle x,\ y\rangle:\ x < y\}\ .\,\!$$

Some results that should be produced by the specification of an extended model:

 * $$f(a, b)\ \mbox{resolves to}\ 1\ \mathrm{in}\ \mathfrak{M}_2\ .\,\!$$
 * $$\mathrm{F}(a, b)\ \mbox{and}\ \mathrm{F}(b, c)\ \mbox{are True in}\ \mathfrak{M}_2\ .\,\!$$
 * $$\mathrm{F}(c, b)\ \mbox{and}\ \mathrm{F}(a, a)\ \mbox{are False in}\ \mathfrak{M}_2\ .\,\!$$

For every x, there is a y such that x < y. Thus we want as a result:

 * $$\forall x\, \exists y\, \mathrm{F}(x, y)\ \mbox{is true in}\ \mathfrak{M}_2\ .\,\!$$

There is no y such that y < 0 (remember, we are restricting ourselves to the domain which has no number less than 0). So it is not the case that, for every x, there is a y such that y < x. Thus we want as a result:

 * $$\forall x\, \exists y\, \mathrm{F}(y, x)\ \mbox{is false in}\ \mathfrak{M}_2\ .\,\!$$

title: Formal Logic/Predicate Logic/Models


text:
Windows Programming/Windows Script Host

The DOS programming model, with it's clumsy batch scripting capabilities was quickly wearing out, and Microsoft needed to add an alternative scripting environment to Windows. The result of this was the Windows Script Host (WSH). WSH comes in two flavors: a console mode version (csh.exe or cscript.exe) and a non-console version (wsh.exe or wscript.exe).

WSH Languages
WSH actually isn't a new language, but is instead an environment for programming in other Active Scripting languages. Active Scripting languages are programming languages that are implemented as COM components. Any Active Scripting language installed on your computer can be used with WSH. By default, WSH can be programmed using JScript and VBScript, but other Active Scripting languages can be installed and run in WSH. One of the more popular 3rd party Active Scripting languages is PerlScript, which is often installed as part of the ActivePerl distribution.

WSH scripts also include a certain amount of XML code, that helps to control the environment of the running script. The language being used to script must be specified in an XML tag.

WSH is an Object Oriented environment, and WSH provided a large number of objects that the Active Scripting languages may tap into.

Another Microsoft technology, Active Server Pages (ASP) is a similar program to WSH in that it is a language-neutral scripting environment that uses installed Active Scripting languages. However, ASP is used as a server-side scripting tool for generating webpages. WSH, in comparison is more well suited for use in scripting a local environment (although WSH can be used as a server-side website scripting engine as well, if you dare!).

Writing a WSH Script
A WSH script file is a plain-text file, that may use a generic ".wsh" file extension. Also, many other file extensions are associated with WSH, and may be more descriptive then the simple .wsh extension. For instance, a WSH script that is primarily VBScript may have the extension ".vbs", and a WSH script that is JScript may have the extension ".js".

Each WSH file must have an XML "JOB" object. Each script may have multiple Jobs, but each job must have an unique ID. For instance, here are some sample job tags:

Next, we must specify the scripting language that we will be using to implement a specific job:

Note from the example that we can include an external source file into our script file, to be run. In a Job object, all the instructions are executed, from the top to the bottom. In each job, we may have multiple different scripting languages in use, in individual blocks.

At the end of a script section, we must close the tag with a " " tag. At the end of a job, we close with a " " tag.

"WScript" Object
WSH provides the WScript object, that has a number of methods and fields for use in a WSH script. The WScript object never needs to be instantiated, and it is always available in any script. As an example, the "Echo" method of the WScript object prints out a certain string. The csh.exe (Console Version) of WSH will print the string to the console, while the wsh.exe (Non-Console Version) will print the string to a message box. Here is a multi-lingual example:

  WScript.Echo("Printing from JScript");  WScript.Echo "Printing from VBScript"  $WScript->Echo("Printing from PerlScript");

Note, of course, that you can't use the PerlScript if you haven't installed it on your computer.

XML Tags
There are a number of other XML tags that can be used in a WSH script.

The tag contains a certain amount of plain text that describes the current file. For instance:

This script writes a status entry to the log file, and updates the website.

Now, this may seem like a difficult way to just write a comment, but the tag also has another purpose. Let's say that we save the above code snippet into a script file, such as "testdesc.wsh". Now, if we run our script with the "/?" argument, we get the following result:

C:\>testdesc.wsh /? This script writes a status entry to the log file, and updates the website.

When we send the argument "/?" to our script, all the text that is written in the tag is printed to the console.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Windows Programming/Windows Script Host


text:
Talk:Latin/Lesson 5-The Subjunctive Perfect

Untitled
How do you conjugate laboare and tenere in the present, imperfect and perfect tenses? —Preceding unsigned comment added by 69.143.249.213 (discuss • contribs) 00:03, 24 February 2006


text:
Windows Programming/JScript

JScript, Microsoft's proprietary version of JavaScript, is a default language in Windows Script Host. JScript is very similar to JavaScript, and was originally created so that JavaScript programmers could put their skills to use scripting a local Windows environment.

title: Windows Programming/JScript


text:
User talk:207.157.220.163

Please do not blank pages
You recently deleted everything from the "Bartending" page, making it blank. We have reverted it.

Please do not blank pages. If you want to experiment with editing Wikibooks, you can use the Sandbox. Thanks, --Kernigh 00:46, 24 February 2006 (UTC)

title: User talk:207.157.220.163


text:
User talk:64.160.96.142

Please do not add irrelevant content to pages
Information added to the "First Aid" book should be about First Aid, for example. If you just want to experiment with Wikibooks, please use our Sandbox. Thank you, --Kernigh 01:15, 24 February 2006 (UTC)

title: User talk:64.160.96.142


text:
Emulation/PlayStation 1

About PlayStation 1
The PlayStation 1 was an extremely popular CD-ROM based 3D gaming system in the 1990's. Because of it's popularity, it has a large library of historically relevant games, as well as a relatively large community of programmers working on emulation for the system.

ePSXe
For original PlayStation emulation, ePSXe is the most compatible. ePSXe is closed source proprietary software, but does offer extension through plugins.

Plugins
One of the features of ePSXe is the ability to use of various plugins. These plugins allow the emulators video, sound, and other input/output systems to be customized to provide the best emulation experience for the users hardware. For example, using an OpenGL based plugin will provide the best video quality for systems with Nvidia graphics cards, sometimes resulting in graphics quality superior to the graphics on the original PlayStation hardware.

System Requirements
Its minimum system requirements are low (Pentium III with 256MB of RAM) but they will differ depending on the game being emulated. More graphically-intensive games such as Final Fantasy 9 will require a more powerful system.

Duckstation
A relatively recent open source PlayStation 1 emulator made with contemporary techniques, focused on being reasonably accurate without sacrificing much performance.

Other PlayStation 1 emulators

 * Mednafen - Open source multi system emulator. Original PS1 core.
 * PCSX-Redux - Fork of the older PCSX-Reloaded.
 * AdriPSX - An older PS1 emulator. Versions exist with very low system requirements.
 * Bleem! - Historic commercial emulator. No longer used except for historical interest.
 * Connectix Virtual Game Station - Historic commercial emulator. No longer used except for historical interest.
 * no$psx - Closed source emulator made by Martin "nocash" Korth.

System Files
The PlayStation 1 uses a BIOS, which most emulators do not include. PCSX-Redux includes OpenBIOS, a full open source PlayStation 1 BIOS replacement, and no$psx includes a closed source BIOS clone. To use other PS1 emulators, one must dump a BIOS from a PlayStation 1 they own.

title: Emulation/PlayStation 1


text:
Talk:Quantum Mechanics

Article on wikipedia
This article was on wikipedia and should be here instead. I have listed the page there for deletion.

 * Sorry unsigned (65.27.115.223), but unproved alternative theories do not belong here either... not even in talk pages. -- ;Sergio.ballestrero 19:43, 6 August 2006 (UTC)
 * A little bit too harch Sergio, If string theorists were treated like that, they would never be published! Pjbeierle (discuss • contribs) 21:18, 21 January 2012 (UTC)

title: Talk:Quantum Mechanics


text:
User:Whiteknight/The PE Exam

I probably will never pursue this book, so I would like to start looking for somebody else to adopt the outline and work on it. If nobody else wants it, I'll probably delete it. --Whiteknight (Page) (Talk) 13:40, 2 December 2008 (UTC)

New Title:  "PE Certification"

Preface
This wikibook is going to serve as a study guide for the FE and PE exams.

PE Certification

 * What are the FE/PE Exams?
 * The PE Process
 * Who Gets the PE?
 * Other Reasons to Take the FE
 * What you are allowed to bring
 * What the testing center provides for you
 * The NCEES Supplied Reference Manual
 * Test Formats

FE Exam Subject Breakdown

 * Mathematics
 * Economics
 * Ethics
 * Dynamics
 * Fluid Mechanics
 * Materials Science
 * Chemistry
 * Statics
 * Circuits
 * Computers
 * Thermodynamics

FE Afternoon Exams

 * The General Exam
 * Civil Engineering
 * Mechanical Engineering
 * Electrical Engineering
 * Chemical Engineering
 * Computer/Software Engineering
 * Industrial Engineering

PE Exam

 * What is the PE?
 * How to Qualify
 * Who Gets the PE?
 * Legal Standing

PE Subject Tests

 * PE Agricultural
 * PE Architectural
 * PE Chemical
 * PE Civil
 * PE Control Systems
 * PE Electrical and Computer
 * PE Environmental
 * PE Fire Protection
 * PE Industrial
 * PE Mechanical
 * PE Metallurgical
 * PE Mining and Mineral
 * PE Naval Architecture and Marine Engineering
 * PE Nuclear
 * PE Petroleum
 * PE Structural I
 * PE Structural II
 * PS

title: User:Whiteknight/The PE Exam


text: Template:French/Appendices

title: Template:French/Appendices


text: Template:French/Grammar

title: Template:French/Grammar


text:
Talk:Greek Mythology/Gods/Hades

Text partially cribbed from the Wikipedia article. --Lnhammer 01:57, 24 February 2006 (UTC)

title: Talk:Greek Mythology/Gods/Hades


text:
Talk:Greek Mythology/Gods/Zeus

Editing Help
How do you insert an image?

Kicked?!
Zeus lay in wait and attacked his father with a sickle, cutting off Kronus´genitals. Any reason the chapter is misrepresenting the myth?

title: Talk:Greek Mythology/Gods/Zeus


text:
User talk:71.195.183.172

Welcome to Wikibooks, collection of open-content textbooks! You don't have to log in to read or edit articles on Wikibooks, but creating an account is quick, free and non-intrusive, requires no personal information, and gives you many benefits, including:
 * The use of a username of your choice
 * The ability to view all your contributions via a "My contributions" link
 * Your own user page
 * Your own talk page which, if you choose, also allows users to send you messages without knowing your e-mail address
 * The use of your own personal watchlist to which you can add articles that interest you
 * The ability to rename pages
 * The ability to upload images
 * The ability to customize the appearance and behavior of the website
 * The eligibility to become an administrator
 * The right to be heard in votes and elections
 * Your IP address will no longer be visible to other users.

We hope that you choose to become a Wikibooks and create an account. We hope you enjoy your time here on Wikibooks as a Wikibookian! -- LV (Dark Mark) 02:29, 24 February 2006 (UTC)

title: User talk:71.195.183.172


text: Template:Wikijunior:Dinosaurs

title: Template:Wikijunior:Dinosaurs


text:
User talk:24.128.88.106

School of Wooden Boat Building & Repair
Hi. I have marked your School of Wooden Boat Building & Repair page as a copyright violation. It appears that you copied some text from the Internet.

Here at Wikibooks, we build free instructional textbooks. We cannot accept random material from the Internet, because most of the Internet is copyrighted and the owners have not given permission to use their text in Wikibooks. If there was copyright permission for School of Wooden Boat Building & Repair, please indicate this. Otherwise, we will delete that page soon. --Kernigh 04:11, 24 February 2006 (UTC)

title: User talk:24.128.88.106


text:
XML - Managing Data Exchange/XLink/Exercises

XLink Chapter => XLink

XLink Answers => Answers

1) Movie Collection
Modify the movie XML document from the many-to-many chapter to use XLink capabilities. Each movie title should be a displayed as an XLink to the movie's description located in "The Internet Movie Database" at http://www.imdb.com/.

the Stylesheet
XLink Chapter => XLink

XLink Answers => Answers


text:
Harmonica/Anatomy of a Harmonica

No matter what kind of harmonica, they are always made up of five basic parts: a comb (also known as body), which is made of plastic, wood or metal, and contains the air channel, as well as supporting the reed plates (or sandwich the comb), which have the reeds blots on to it. This sandwich is further sandwiched by two coverplates, which provide a place to grip the harmonica, as well as producing the aural quality.

In the past, the parts were nailed onto the comb, and this is still common with some wooden combs. However, in modern times, most of them are secured using screws.

Blues Harp and Tremelo Harmonica

 * Comb
 * Reed plates
 * Reed
 * Cover plates and cover posts

The construction of tremolo harmonicas and blues harps is very similar. However, blues harps traditionally have all blow reeds on one plate and all draw reeds on the other one, while tremolo harps have both blow and draw reeds on one plate; the other plate differs mainly by the aural frequency the reeds produce. The combs also differ - a blues harp's comb really resembles a comb, while a tremolo harp has a separator across the comb's equator, which separates the air channel for both reed plates.

Hohner XB-40
While ultimately it is a Richter tuned harmonica, it differs by having the following construction:
 * mouthpiece
 * Body
 * Windsaver (aka valve)
 * The body is split into two halves along the equator, and each half contains a windsaver, a small piece of flexible flim that is slightly larger than the air channel. They worked by following the air flow produce, which either open up the reed, or completely block air to reach the reeds. In the XB-40, this separates the blow and draw chambers, allowing activation of appropriate notes through bending.
 * reed plates
 * Unlike the standard blues harp, the XB-40 contains both blow and draw reeds. The normally blow plate will contain blow reeds that is offset as usual, while the draw reeds will be at zero offset (i.e. at the same level of the plate). This results in allowing muting draw reeds when not bending, but open up for blow bend when needed. Draw plates is construct and operate similarly.
 * cover plates

Chromatic harmonica
Being even more complex than the XB-40, chromatic harmonicas have even more parts:
 * Mouthpiece
 * Slide compartments
 * If cross-tuned - made up of 2 parts: the slide and the slide plate
 * If straight-tuned - Made up of a slide plate, the slide, and the slide cover.
 * Slide buffers
 * Counterlock screws
 * Located inside the comb of Hohner 280, Super 64, and Super64X, it was used to help mount the mouthpiece screws.
 * Spring
 * Spring Post
 * Where the spring are held in place.
 * Comb
 * While its purpose is still supporting the parts of the harmonica, the construction of it is more complex, in order to accommodate the spring post and mouth piece.
 * Reed plates
 * Reed
 * Windsavers
 * a small piece of flexible film that is slightly larger than the air channel. They work by following the air flow produce, which either open up the reed, or completely block air to reach the reeds. In the chromatic, they help direct more air to the appropriate reeds, thus making the reed respond better.
 * Cover plates and cover posts

title: Harmonica/Anatomy of a Harmonica


text: Template:French/Grammar/Tenses and moods


text:
Talk:Mythology/Greek Mythology

Its probably not necessary to have a Greek Mythology section of Mythology, and also have a separate book.

I plan to merge this section and that book together. Until then, I use merge templates to provide (to the readers) the links between the two parts. --Kernigh 05:34, 24 February 2006 (UTC)

I think there can be a greek mythology section of Mythology, but there should also be a stand-alone Greek Mythology book. Trooper209 09:07, 24 February 2006 (UTC)Trooper209 1:06, 24 February 2006 (PST)

title: Talk:Mythology/Greek Mythology


text:
Computer Go/Kiseido Go Server

The KGS Go Server (http://www.gokgs.com/), formerly known as the Kiseido Go Server, is an on-line place for Go players, both human and computer, to find opponents to play against. KGS has special features for teaching purposes and reviewing games, and a ranking system to make it easy to find players of a similar strength.

kgsGtp is a program that will allow any Go program that implements GTP to play against other computers and humans on KGS.

title: Computer Go/Kiseido Go Server


text:
Greek Mythology/Gods/Zeus

Zeus was the son of Cronos and Rhea. Zeus took away his father's position on the Throne of Eternity. Cronos heard a prophecy that one of his sons was going to depose him, so he started eating all his children. When the sixth child, Zeus, was born, Rhea replaced Zeus with a stone when he was about to be eaten. When Cronos became aged, Zeus came out of hiding and gave Cronos a magic potion to drink. Cronos vomited up the stone and the other five undigested gods and goddesses: Hades, Poseidon, Hera, Hestia, Demeter. Out of gratitude, the other gods made Zeus the leader of all immortals. Zeus' domain was the mountain tops and clouds from where he could survey all creation. He married his elder sister Hera and because Zeus had many love affairs with other goddesses and mortals Hera became jealous. From that jealousy came an abundance of divine wrath upon the mortals.

Names of Zeus
Zeus had many names. Here are some of them:

 * God
 * Zeus of the Aegis
 * Zeus the Cloud Gatherer
 * Zeus of the Wide Brows
 * Father Zeus
 * Son of Cronos
 * Lord of Hera
 * Zeus of the Thunderbolt
 * Father of Gods and Men
 * Zeus on High
 * The Sky Dweller
 * The Olympian
 * Jupiter (In Roman Mythology.)

title: Greek Mythology/Gods/Zeus


text:
Greek Mythology/Gods/Artemis

Artemis (identified as Diana in Roman mythology) was the 'Lady of the Wild Things' and 'Huntsman-in-chief to the gods'. She was the daughter of Zeus and Leto. She is the sister of Apollo, and they were both born on the island Delos. They both are associated with the bow. Although Artemis is associated with the Silver Bow, and Apollo, the Curved Bow. Artemis is one of three people immune to Aphrodite's enchantments. She has a special friendly mutual relationship with all the mortals. She walks around all the time in her silver sandals giving special divine protection to the animals, especially the very young. She also loves to ride in the sky on her silver chariot shooting her silver moonlight arrows upon the world.

title: Greek Mythology/Gods/Artemis


text:
Template:French/Exercise

 Exercise

title: Template:French/Exercise


text:
Greek Mythology/Gods/Athena

Athena was the goddess of battle strategy, and wisdom. Identified in the Roman mythology as the goddess Minerva. She was always accompanied by her owl and the goddess of victory, Nike. Also known as Pallas Athena, she wore a breastplate made out of goatskin called the Aegis, which was given to her by her father, Zeus. She had many names that explain her. Some of her names are helmet head, Athena the wise, and others.

Athena was an armed warrior goddess. The Parthenon at Athens was her most famous shrine. She never had a true lover. For some strange reason it was hopeless that she would fall in love; Hephaestus tried once, yet failed. Athena was well known for giving advice/mentoring heroes. One example of that is in The Odyssey, where Athena assists Odysseus' son Telemachus in finding his father; another is where she gives Perseus the shield he will need to fight Medusa.

Athena's mother was Metis. Metis warned Zeus that if she bore him a boy child, the child would be greater than him. Zeus swallowed her and started having a terrible headache. Then his head split open by an axe from help from Hephaestus. Suddenly, Athena came out of his head. Athena came out fully grown, with her symbols the aegis and the famous helmet of Athena. Athena is much like her brother Ares: They are both rulers of war, but she is more of the strategy and quick thinking. Her brother Ares is the power, strength, and villain of mythology. Athena is also known of being and having Wisdom, Wealth and Crafts.

Athens is named after Athena for memory of her. She has proved her skills for craft for making cloth. Once a young maiden named Arachne, who was a very talented weaver, claimed that she was a better weaver then Athena herself. So Athena came down to Earth to test Arachne. Athena and Arachne competed in weaving a tapestry. At the end of the competition Arachne made a tapestry mocking the gods, which sent Athena into such an uncontrollable rage that she turned Arachne into a spider, thus creating the name Arachne.

title: Greek Mythology/Gods/Athena


text:
User:PS2pcGAMER

I am very active on wikipedia. If I don't reply to messages left on my talk page within a day or so, please let me know on my Wikipedia user talk page.

title: User:PS2pcGAMER


text:
User:Gary Kirk

You'll find me more active on Wikipedia than here. On Meta-Wiki I mainly fix any typos I find, but again, I don't go there that often.

I made my first edit at English Wikibooks on February 24th 2006 - FYI, today is July 29 2024.

Current Tasks

 * Capture, annotate and uploac more screenshots of my MS Access database application, Obelisk SRC. Gary Kirk 20:47, 25 February 2006 (UTC)

title: User:Gary Kirk


text:
User talk:Gary Kirk

Welcome
Hello and welcome to Wikibooks!

Here are some tips to help you get started:
 * You can sign your name on Talk and vote pages using four tildes, like this: ~~~~.
 * Remember to conduct any editing experiments in the sandbox.
 * Check out our help page if you need additional help.
 * Eventually, you might want to read the Manual of Style and Policies and Guidelines.
 * Take a look at Naming policy
 * See list of templates which can save your time
 * Remember to maintain a Neutral point of view.
 * Explore, be bold in editing pages, and have fun!

You will find more resources in Community Portal. If you want to ask a question, visit the Study help desk, the Staff lounge, IRC channel or ask me personally on my talk page.

Good luck!--Derbeth talk 10:25, 24 February 2006 (UTC)

title: User talk:Gary Kirk


text:
C Sharp Programming/Generics

Generics are a new feature available since version 2.0 of the C# language and the common language runtime (CLR). Generics introduce to the .NET Framework the concept of type parameters, which make it possible to design classes and methods that defer the specification of one or more types until the class or method is declared and instantiated by client code. The most common use of generics is to create collection classes. Generic types were introduced to maximize code reuse, maximizing type safety, and performance.

Generic classes
There are cases when you need to create a class to manage objects of some type, without modifying them. Without generics, the usual approach (highly simplified) to make such class would be like this:

And its usage would be:

Note that we have to cast back to original data type we have chosen (in this case - ) every time we want to get an object from such a container. In such small programs like this, everything is clear. But in more complicated cases with more containers in different parts of the program, we would have to take care that the container is supposed to have type in it and no other data type, as in such a case, a  is thrown.

Additionally, if the original data type we have chosen is a value type, such as, we will incur a performance penalty every time we access the elements of the collection due to the autoboxing feature of C#.

However, we could surround every unsafe area with a -  block, or we could create a separate "container" for every data type we need just to avoid casting. While both ways could work (and worked for many years), it is unnecessary now, because generics offers a much more elegant solution.

To make our "container" class to support any object and avoid casting, we replace every previous type with some new name, in this case, and add  mark immediately after the class name to indicate that this  type is generic/any type.

 * Note: You can choose any name and use more than one generic type for class, i.e.

Not a big difference, which results in simple and safe usage:

Generics ensures that you specify the type for a "container" once, avoiding previously mentioned problems and autoboxing for s.

While this example is far from practical, it does illustrate some situations where generics are useful:
 * You need to keep objects of a single type in a class
 * You do not need to modify objects
 * You need to manipulate objects in some way
 * You wish to store a "value type" (such as, , , or any custom ) in a collection class without incurring the performance penalty of autoboxing every time you manipulate the stored elements.

Generic interfaces
A generic interface accepts one or more type parameters, similar to a generic class:

Generic interfaces are useful when multiple implementations of a particular class are possible. For example, both the class (discussed below) and the  class, both from the  namespace, implement the  interface. has a constructor that creates a new list based on an existing object that implements, and so we can write the following:

Generic methods
Generic methods are very similar to generic classes and interfaces:

This method can be used to search any type of array:

Type constraints
One may specify one or more type constraints in any generic class, interface or method using the keyword. The following example shows all of the possible type constraints:

These type constraints are often necessary to

 * 1) create a new instance of a generic type (the ) constraint
 * 2) use  on a variable of a generic type (the  constraint)
 * 3) use  on a variable of a generic type (the  constraint)

title: C Sharp Programming/Generics


text:
Organic Chemistry/Amines

Amines are organic compounds which contain and are often actually based on one or more atoms of nitrogen. Structurally amines resemble ammonia in that the nitrogen can bond up to three hydrogens, but amines also have additional properties based on their carbon connectivity. In an amine, one or more of the hydrogen atoms from ammonia are replaced by organic substituents like alkyl (alkane chain) and aryl (aromatic ring) groups.

Another type of organic molecule contains nitrogen without being, strictly speaking, an amine: carboxylic acid derivatives containing a trivalent (three-bond) ammonia in ground state are actually amides instead of amines. Amides and amines have different structures and properties, so the distinction is actually very important. Organic-nitrogen compounds containing metals are also called amides, so if you see a molecule that has a nitrogen and either a carbonyl group or a metal next to that nitrogen, then you know that molecule should be an amide instead of an amine.

= Preparation = The following laboratory methods can be considered to be in common use for purpose of the preparation of amine compounds:

From Oximes
H     | R-C=N - OH + H > Na / Ethanol  R-CH2-NH2 + H2O
 * Aldoximes or ketoximes are reduced by sodium and ethanol to corresponding primary amines

The Gabriel Phthalimide synthesis
used for preparation of primary amines. Aromatic primary amines can't be prepared by this method because aryl halides do not undergo nueleophilic substitution with potassium phthalimide.
 * via azides by the Staudinger reduction.
 * Allylic amines can be prepared from amines in the Aza-Baylis-Hillman reaction.

Hofmann degradation of amides
This reaction is valid for preparation of primary amines only, and it gives good yields of primary amines uncontaminated with other amines.
 * Hofmann Rearrangement Scheme.png

Hofmann elimination of quaternary ammonium salts

 * R3N+CH2CH2R' + OH- → R3N + H2C=CHR' + H2O

 * Quaternary ammonium salts, upon treatment with a strong base, undergo the Hofmann Elimination.

Reduction of nitriles and amides

 * Nitriles are reduced to amines using hydrogen in the presence of a nickel catalyst, although acidic or alkaline conditions should be avoided to avoid the possible hydrolysis of the -CN group.
 * LiAlH4 is more commonly employed for the reduction of nitriles on the laboratory scale.

 * Similarly, LiAlH4 reduces amides to amines.

Nucleophilic substitution of haloalkanes
Primary amines can also be synthesized by alkylation of ammonia. Haloalkanes react with amines to give a corresponding alkyl-substituted amine, with the release of a halogen acid. Such reactions, which are most useful for alkyl iodides and bromides, are rarely employed because the degree of alkylation is difficult to control. If the reacting amine is tertiary, a quaternary ammonium cation results. Many quaternary ammonium salts can be prepared by this route with diverse R groups and many halide and pseudohalide anions.

= Properties =

Types of Amines
Amines can be either primary, secondary or tertiary, depending on the number of carbon-containing groups that are attached to them. If there is only one carbon-containing group (such as in the molecule CH3NH2) then that amine is considered primary. Two carbon-containing groups makes an amine secondary, and three groups makes it tertiary. Utilizing the lone electron pair of nitrogen, it is sometimes energetically favored to use the nitrogen as a nucleophile and thus bind a fourth carbon-containing group to the amine. In this case, it could be called a quaternary ammonium ion.

An organic compound with multiple amine groups is called a diamine, triamine, tetraamine and so forth, based on the number of amine groups (also called amino groups) attached to the molecule. The chemical formula for methylene diamine (also called diaminomethane), for example, would be as follows: H2N-CH2-NH2

Aromatic amines
Aromatic amines have the nitrogen atom directly connected to an aromatic ring structure. Due to its electron withdrawing properties, the aromatic ring greatly decreases the basicity of the amine - and this effect can be either strengthened or offset depending on what substituents are on the ring and on the nitrogen. The presence of the lone electron pair from the nitrogen has the opposite effect on the aromatic ring itself; because the nitrogen atom can "loan" electron density to the ring, the ring itself becomes much more reactive to other types of chemistry.

Naming conventions
For primary amines, where the amine is not the principal characteristic group, the prefix "amino-" is used. For example: 4-aminobenzoic acid where the carboxylic acid is the principal characteristic. Otherwise, the suffix "-amine" is used with with either the parent hybride or the R group substituent name. Example: ethanamine or ethylamine. Alternatively, the suffix "-azane" can be appended to the R group substituent name: Example: propylazane.

For secondary, tertiary, and quarternary amines, the naming convention is a bit different, but the suffixes are the same. For symmetrical amines, the "di" or "tri" prefix is used depending on whether there are 2 or 3 substituents. For example, dipropylamine is a secondary amine, and triphenylamine is a tertiary amine. For asymmetric amines, the parent chain gets the "-amine" suffix. This name is then prefixed with "N-" (indicating the nitrogen bond) and the substituent group name, for each substituent, using alphabetic order for tertiary amides. For example, N-ethyl-N-methyl-propylamine, not N-methyl-N-ethyl-propylamine.

To sum up:

 * as prefix: "amino-"
 * as suffix: "-amine"
 * the prefix "N-" shows substitution on the nitrogen atom (in the case of secondary, tertiary and quaternary amines)

Systematic names for some common amines:

 * Primary amines: ethanamine or ethylamine.
 * Secondary amines: dimethylamine
 * Tertiary amines: trimethylamine

Physical properties
As one might readily guess, the inclusion of a heteroatom such as nitrogen in otherwise exclusively carbon and hydrogen molecules has quite an effect on the properties of amines as compared to alkanes.

General properties
Hydrogen bonding significantly influences the properties of primary and secondary amines as well as the protonated derivatives of all amines. Thus the boiling point of amines is higher than those for the corresponding phosphines (compounds containing phosphorus), but generally lower than the corresponding alcohols. Alcohols, or alkanols, resemble amines but feature an -OH group in place of NR2. Since oxygen is more electronegative than nitrogen, RO-H is typically more acidic than the related R2N-H compound.

Methyl, dimethyl, trimethyl, and ethyl amines are gases under standard conditions. Most common alkyl amines are liquids, and high molecular weight amines are, quite naturally, solids at standard temperatures. Additionally, gaseous amines possess a characteristic ammonia smell, while liquid amines have a distinctive "fishy" smell.

Most aliphatic amines display some solubility in water, reflecting their ability to form hydrogen bonds. Solubility decreases relatively proportionally with the increase in the number of carbon atoms in the molecule - especially when the carbon atom number is greater than six. Aliphatic amines also display significant solubility in organic solvents, especially in polar organic solvents. Primary amines react readily with ketone compounds (such as acetone), however, and most amines are incompatible with chloroform and also with carbon tetrachloride as solvent solutions.

Aromatic amines have their lone pair electrons conjugated ("shared") into the benzene ring, so their tendency to engage in hydrogen bonding is somewhat diminished. The boiling points of these molecules are therefore usually somewhat higher than other, smaller amines due to their typically larger size. They also often have relatively diminished solubility in water, although they retain their solubility in other organic solvents.

Aromatically conjugated amines are often quite toxic and have the potential to be easily absorbed through the skin, so should always be treated as "hazardous".

Chirality
Tertiary amines of the type NHRR' and NRR'R" are not chiral: although the nitrogen atom bears four distinct substituents counting the lone pair, the lone pair of electrons can "flip" across the nitrogen atom and invert the other molecules. The energy barrier for just such a Walden inversion of the stereocenter with a lone pair of electrons is relatively low, e.g. ~7 kcal/mol for a trialkylamine, therefore it is difficult to obtain reliably chiral products using tertiary amines. Because of this low barrier, amines such as NHRR' cannot be resolved optically and NRR'R" can only be resolved when the R, R', and R" groups are constrained in cyclic structures. Quaternary amine structures, e.g. H3C-N+-RR'R", are chiral and are readily optically resolved.

Properties as bases
Like ammonia, amines act as bases and are reasonably strong (see the provided table for some examples of conjugate acid Ka values). The basicity of amines varies by molecule, and it largely depends on:
 * The availability of the lone pair of electrons from nitrogen
 * The electronic properties of the attached substituent groups (e.g., alkyl groups enhance the basicity, aryl groups diminish it, etc.)
 * The degree of solvation of the protonated amine, which depends mostly on the solvent used in the reaction

The nitrogen atom of a typical amine features a lone electron pair which can bind a hydrogen ion (H+) in order to form an ammonium ion -- R3NH+. The water solubility of simple amines is largely due to the capability for hydrogen bonding that can occur between protons on the water molecules and these lone pairs of electrons.

---

+I effect of alkyl groups raises the energy of the lone pair of electrons, thus elevating the basicity.
 * Inductive effect of alkyl groups

+M effect of aromatic ring delocalizes the lone pair electron into the ring, resulting in decreased basicity.
 * Mesomeric effect of aromatic systems

The degree of protonation of protonated amines:

= Reactions =

Amide formation
Acyl chlorides and acid anhydrides react with primary and secondary amines without the presence of heat to form amides. Tertiary amines cannot be acylated due to the absence of a replaceable hydrogen atom. With the much less active benzoyl chloride, acylation can still be performed by the use of excess aqueous base to facilitate the reaction.

Salt formation
Because amines are basic, they neutralize carboxylic acids to form the corresponding ammonium carboxylate salts. Upon heating to 200°C, the primary and secondary amine salts dehydrate to form the corresponding amides.

Neutralization
Amines R3N react with strong acids such as hydroiodic acid (HI), hydrobromic acid (HBr) and hydrochloric acid (HCl) to give ammonium salts R3NH+.

Reaction with nitrous acid
Nitrous acid with the chemical formula HNO2 is unstable. Usually it is produced indirectly in a mixture of NaNO2 and a strong acid such as HCl or H2SO4 in dilute concentration, so that the H+ ions will associate with the NO2- ions in solution.

Primary aliphatic amines with nitrous acid give very unstable diazonium salts which spontaneously decompose by losing N2 to form a carbenium ion. The carbenium ion goes on to produce a mixture of alkenes, alkanols or alkyl halides, with alkanols as the major product. This reaction is of little synthetic importance because the diazonium salt formed is too unstable, even under quite cold conditions.
 * NaNO2 + HCl → HNO2 + NaCl

 * Primary aromatic amines, such as aniline (phenylamine) forms a more stable diazonium ion at 0–5°C. Above 5°C, it will decompose to give phenol and N2. Diazonium salts can be isolated in the crystalline form but are usually used in solution and immediately after preparation, due to rapid decomposition on standing even with little ambient heat. Solid diazonium salts can be explosive on shock or on mild warming.

Reactions with ketones and aldehydes

 * Primary amines react with carbonyl compounds to form imines. Specifically, aldehydes become aldimines, and ketones become ketimines. In the case of formaldehyde (R' = H), the imine products are typically cyclic trimers.

 * RNH2 + R'2C=O → R'2C=NR + H2O

 * Secondary amines react with ketones and aldehydes to form enamines. An enamine contains a C=C double bond, where the second C is singly bonded to N as part of an amine ligand.

 * R2NH + R'(R"CH2)C=O → R"CH=C(NR2)R' + H2O

= Use of amines =

As dyes
Primary aromatic amines are used as a starting material for the manufacture of azo dyes. They react with nitrous(II) acid to form diazonium salt which can undergo a coupling reaction in order to form an azo compound. As azo compounds are highly coloured, they are widely used in dyeing industries. Examples include:
 * Methyl orange
 * Direct brown 138
 * Sunset yellow FCF
 * Ponceau

As drugs

 * Chlorpheniramine is an antihistamine the helps to relief allergic disorders due to cold, hay fever, itchy skin, insect bites and stings.
 * Diphenhydramine is the common antihistamine, benadryl.
 * Chlorpromazine is a tranquillizer that sedates without inducing sleep. It is used to relieve anxiety, excitement, restlessness or even mental disorder.
 * Acetaminophen is also known as paracetamol or p-acetaminophenol, an analgesic that relieves pains such as headaches. It is believed to be less corrosive to the stomach and is an alternative to aspirin.

= See also =
 * IUPAC nomenclature for the official naming rules for amines.

title: Organic Chemistry/Amines


text:
User:Unbreakable MJ~enwikibooks

See my user page on WP.

Updated by UnbreakableMJ 00:41, 23 October 2006 (UTC)

title: User:Unbreakable MJ~enwikibooks


text:
Screen Printing

Screen printing is a relatively simple and inexpensive way to make detailed prints on a diverse set of substrates including cloth, paper, bumper stickers, and posters. The process involves creating a stencil on a piece of polyester material stretched over a frame, and then transferring ink through the open mesh openings onto the substrate.

Contents

 * An Introduction to Screen Printing
 * /Brief History/
 * /Planning and Executing your Project/
 * /Materials/
 * /Making the Stencil/
 * Stenciling Techniques
 * Photo Emulsion Technique
 * /Making the Print/
 * /Finishing Up/
 * /Advanced Techniques/
 * /Common Problems/
 * /Project Ideas/
 * /Selling your Prints/

title: Screen Printing


text:
User talk:Rayleung2709~enwikibooks

Organic Chemistry/Amine
I noticed that you copied Amine to Organic Chemistry/Amine. It seems that you wanted to help Wikibooks create a free Organic Chemistry textbook.

However, Organic Chemistry/Amine currently has three problems:
 * 1) It gives no credit to Wikipedia contributors for being the author. I fixed this by adding a History section, making clear that the page is based on a Wikipedia article, as the GNU Free Documentation License section 4 asks me to do.
 * 2) It has a large number of red links that do not point to any textbook. I fixed this by changing them into Wikipedia links, like organic compound for organic compound.
 * 3) It reads like an encyclopedia article, not a chapter of the Organic Chemistry textbook. This third problem continues.

Our textbooks are not collections of encyclopedia articles; we already have Wikipedia for that! Unless you want to rewrite Organic Chemistry/Amine as a textbook chapter, it might be better to delete it and provide a link to the Wikipedia article. It is easier to have only one version of the encyclopedia article, not two. --Kernigh 17:10, 24 February 2006 (UTC)

Follow-up
I noticed the notice that was placed on the page in question. I have begun the process of turning the encyclopedia article into more of a "learning style" form of writing. The encyclopedia article was a good start, and I'm going with it (mostly) but it will need to be tweaked even after I finish de-encyclopedizing it. Justin 09:41, 7 May 2006 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Rayleung2709. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Rayleung2709~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:40, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 05:24, 19 April 2015 (UTC)

title: User talk:Rayleung2709~enwikibooks


text:
Organic Chemistry/Foreword

Purpose and mission
This book should become the gold standard of organic chemistry texts in the areas of accuracy, usability, flexibility, and connection with its audience. As this text is developed it will always be available online, be printable, and freely distributable. This text should eliminate all or much of the cost for owning an up-to-the-minute, top-quality college-level organic chemistry text, as it and all its derivative works will remain free: free as in speech as well as free as in beer. Although you could pay for a printed version if you wanted to.

Content and Contributions
This is, to the best of our knowledge, the world's first and only open content organic chemistry textbook. Its users will tweak and refine this book until there is no better book. We are confident that this will happen because the process has already been seen to work many times on the Wikipedia site.

All content contained herein is available under licences that allow free distribution. You can copy it, print it, sell it, and create derivative works from it.

Our restriction: if you create derivative works, make them available to others in a way that they can easily copy and distribute them, as we have done for you.

We link to some pages outside our server. Any of this content not found under the Wikipedia site and subsites is not ensured to be under the same license; it in fact is most likely not.

Navigation
I like the navigation that I have worked out in the Foundational concepts of organic chemistry page and immediate subpages with links at the top of the page to the immediate next and previous pages and the various levels, and links at the bottom to the next and previous chapters, etc. If you want to help out please help me get all of the pages in the same format.

Licensing
All work in this book is released at the moment only under the GNU FDL license. However this is only one of many similar open content licenses, and may not be the license of choice for everyone. To take content written by Karl Wick from this book for release under other licenses please contact the author through this page's associated talk page.

How to study organic chemistry
One of the main difficulties students have with organic chemistry is organizing the information in their minds. By the second semester of organic chemistry, students will learn over 100 chemical reactions. Consequently, it is vital that students take time to not only organize the information, but also to understand it. Indeed, excellent organic professors will tell you, contrary to popular belief, that you do not really need to memorize anything for organic chemistry, instead you simply need to understand it. By truly learning something, rather than memorizing it, you will be able to apply concepts beyond what you are memorizing.

When you see something in the textbook, always ask why something is the case. Do research, try to find out the answer. By taking this approach you will enrich your learning experience, and the information will be "locked" in your mind.

Each person may have a slightly different method that helps him or her learn organic chemistry the quickest and with least pain. The basic rule of thumb is to use a method that you find most helpful and stick with it. Various study methods include flash cards, molecular model kits, group study, writing chemical reactions on blackboards, others just take the class over and over until they "get it".

The writers would recommend to buy a molecular model kit so you can hold in your hand and visualize in your mind how the molecules look in three-dimensional space. If you can't get access to models or can't afford them, look online for sites that use the Jmol application or other rendering software that allow you to virtually rotate molecules.

It cannot be stressed enough that you must be able to visualize molecules in organic chemistry. The 3 dimensional structure of molecules often plays a crucial part in reactions. It can be the deciding factor in whether a reaction even happens, it can decide how fast it happens, and it can decide what the product(s) of the reaction is going to be. If you can't visualize the 3D structure, you won't be able to understand what's happening.

Sports analogy
You can think of the different elements and functional groups as players in a game and the organic reactions as the plays. Just as each player or team has different strengths or characteristics and uses strategies to achieve what they want, organic chemists use the properties of each chemical to play off the others in order to achieve a desired end result.

Language analogy
You can also think of organic chemistry like learning a foreign language. The atoms, for example, carbon and hydrogen and oxygen and nitrogen, are the letters of the alphabet. The structural theory of organic chemistry, namely, the tetravalencey of carbon, may be considered the essential underlying grammatical rule. All organic compounds are assembled under these grammatical rules, and may be considered words. The reactions of organic compounds may be perceived as the assembly of these words into sentences. A language analogy is also useful at this point, because the grammatical rules that control the assembly of sentences (formation of the products of organic reactions!) may be found in the study of organic reaction mechanisms.

Therefore, it is not necessary to memorize individual reactions. Overall patterns of reactivity become obvious when the mechanism of the reaction is investigated. Moreover, like any language, you have to practice it constantly. The more you "read" and "speak" chemical reactions and understand the mechanisms by which they proceed, the more fluent you will become. When you finish organic chemistry, you will literally be able to read, write, and speak in a foreign language. However, it is important to note that the language of organic chemistry is far simpler than any language people use for general communication! The words mean exactly what they mean, and the basic rules almost never change. But organic chemistry is far from a dead science. In fact, it is one of the most active and rapidly advancing areas in modern science today.

Research produces new knowledge, and the potential to formulate new rules. Perhaps you will make some of these discoveries, and future students will refer to your rules.

Foreword | Foundational concepts >>

title: Organic Chemistry/Foreword


text: User:Fnfd

title: User:Fnfd


text:
Talk:Organic Chemistry/Amines

I marked this module for cleanup and posted to User talk:Rayleung2709 about this. --Kernigh 17:39, 24 February 2006 (UTC)

I'll start cleaning it up. Justin 22:49, 4 May 2006 (UTC)

I got through it partway, I'll finish it in a few days. Justin 09:38, 7 May 2006 (UTC)

 * Alright, it needs some more polishing, but it's basically alright now. Justin 00:24, 9 May 2006 (UTC)

Moved from the article itself
''This module was adapted from the Wikipedia article Amine at 24 February 2006, used under GNU Free Documentation License. It was then modified to be more suitable for a textbook format.''

title: Talk:Organic Chemistry/Amines


text:
Screen Printing/Making the Stencil

The stencil, which is created on polyester mesh, defines the art to be printed. The stencil consists of a solid area that will not allow the ink to pass and an open area that will allow the ink to be deposited on the substrate.

There are a variety of ways to create stencils suitable for screenprinting. The following sections briefly summarize some of these processes, and the associated sub pages go into more elaborate detail and how-to information.

Photo Emulsion
The use of a photo emulsion allows the creation of a stencil with near photographic quality. It is perhaps the easiest way in which to make a stencil at a very low cost of approximately USD$0.25 per square foot of stencil area.

Learn How

title: Screen Printing/Making the Stencil


text:
Screen Printing/Making the Print

Printing is a pretty simple procedure though it takes some practice to really master it. With the frame turned upside down (flat side down) you add a line of your printing ink to one edge of the screen. Using a rubber squeegee, you smooth the ink over the entire stencil. This is called the flood stroke and the purpose is to fill the stencil with ink. Next you place the stencil on the item you`re printing on, still flat side down, and use the squeegee again, this time moving in the opposite direction, to spread the ink over the stencil and force it through the screen. That's all there is to it. Most ink should just wash off the screen with tap water without disturbing the stencil. Once it's dry you're ready to print again. Or if you're using the same color, you can print right away, just don't let the paint dry too much on the stencil, it could be difficult to wash out without destroying the stencil.

title: Screen Printing/Making the Print


text:
Screen Printing/Finishing Up

Different inks and materials will require different treatments after printing. Most fabric ink require you to use a clothes iron on the printed fabric after the ink dries, in order to heat set the ink so it won't wash out in the washer. Read the instructions for your ink to see what is required.

Reclaiming
After you've printed, you can save your stencil indefinitely, but obviously you can't reuse the same screen for another stencil, without first removing the old stencil. The process of removing a stencil from the screen is called reclaiming the screen, and it's usually just a matter of applying a special chemical to remove the photo emulsion. Remember that once exposed, water alone is not enough to wash out the emulsion. Fortunately, a number of different solutions are available that will wash out exposed emulsion. Check the instructions for your emulsion to see what it recommends, but usually a low strength paint thinner will work, or you can buy a solution called Stencil Remover quite cheaply and this does the trick well. You simply pour a small amount of the solution over the stencil, rub it in, and then wash it out. The emulsion should wash out with it.

As an alternative, it is possible to remove a screen from the frame, so you can save the stencil and still have the frame available for new stencils. Stretch another screen over the frame and you're good to go. If you're careful removing the stencil, you should be able to reapply it to a frame at a later time if you decide you want to print it again. This way, you only need a few frames, but you can create a veritable library of stencils which you can reuse whenever you want.

title: Screen Printing/Finishing Up


text:
Inuktitut

Lessons

 * Lesson 1 - Inuktitut Syllabary

Also See
Wikijunior Inuktitut

title: Inuktitut


text:
Talk:French/Vocabulary/Dates, time, and numbers

Untitled
I think there is a mistake in the numbers apendix.

quote: Numbers eighty-one to ninty-nine are configured in the form of quatre-vingts-[01-19]. For example eighty-one is quatre-vingt-un (4*20-one), ninty is quatre-vingt-dix (4*20-10), and ninty-four is quatre-vingt-quinze(4*20-14). unquote

quinze is fiften not fourteen as stated in the last sentence

193.63.48.48 19:31, 24 February 2006 (UTC)


text:
Talk:United States Government/The Later Amendments

In regards to 14th amend. being "Law", see Dyatt v Turner, 439 P2d 266. In regards to Oregon purportedly "ratifying" 14th amend. in 1866, see H.J.R. 13,(Oregon, 1973). Oregon Senate President was to have signed this legislation on May 21, 1973; but see Oregon Senate Journal of that date. No reading of bill; no signature. ??

71.34.243.133 19:34, 24 February 2006 (UTC)


text: Screen Printing/Advanced Techniques

title: Screen Printing/Advanced Techniques


text:
Screen Printing/Common Problems

Over-Exposure
Over-exposure causes a loss of detail in your image area. When photo emulsion is exposed to UV light, it polymerizes or will crosslink, making it more difficult to wash out. As UV light reaches the photo emulsion it becomes crosslinked, rendering it difficult or impossible to wash out during the development stage. This over-exposure happens when photo emulsion stencil making when the exposure is longer than it should be and the UV light begins to creep around the edges of the positive areas of your art, thus decreasing fine lines or completely obliterating them. Extreme over-exposure can "burn" through the opaque areas of the film positive rendering the stencil a solid block of hardened emulsion.

Common Causes of Over-Exposure
An excess of UV light reaching the stencil causes over-exposure. This is often caused by the use of film positives that are not made of optically clear film. The use of semi-opaque positives such as vellum materials will require a longer exposure time, and thus the UV light may penetrate the opaque areas of the film positives much quicker. One should always be more concerned with the minimum density, i.e. the clear areas, of the film positive than the maximum density or solid areas of the film positive. The contrast between the clear and opaque area of the film positive must be extreme for the film positive / UV light / photo emulsion combination to work well.

Wide spread over-exposure is likely to happen if your positive material is not transparent enough to allow the UV light to harden the photo emulsion before the UV light has penetrated the maximum density areas of the film positive. Clear film positives allow 91-percent of the UV light to reach the stencil, where vellum allows only 54.5-percent of the light to pass. This amounts to a 36.5% difference in light transmission, thus a 5 minute exposure using film would increase to 6.825 minutes using vellum positive. This two minute difference in exposure can cause the UV light to completely pass through the opaque areas of the film positive.

Loss of Detail
All light will bend and thus an over-exposed stencil will result in the light bending around the edges of the details in the film positive. Thin lines will be decreased or be completely obliterated. Utilizing the correct exposure time will lessen the loss. Also, assuring that details are sufficient for the mesh count used will achieve this goal. The finest detail that one should attempt to print with a specific mesh count will be equal to the width of one mesh opening and two threads. The size of mesh openings and thread width, stated in microns, is readily available from all mesh manufacturers.

If you made the film positive by hand double siding you should use a clear film positive with an opaque ink. If you printed or copied directly onto the transparency, try increasing the darkness of the image. It is possible to use two copies sandwiched together, as long as the clarity of the minimum density areas are not affected. Reread the section on making positives for more information.

Widespread over-exposure can also happen if you allow the photo emulsion to receive too much exposure. Light will pass through the maximum density areas of the film positive given enough time, thus exposing the emulsion. Reread the section on exposing the screen for more information.

Similarly, UV light that reaches the photo emulsion drying or storage stage could expose the emulsion. Screens may be coated in ordinary room light, but should be stored in an area that is devoid of UV light. Ordinary room light will cause the photo emulsion to harden in a matter of minutes, thus the stencil should be stored in a light-safe environment applying the emulsion to the screen. Reread "Drying the Screen" for more information.

Local over-exposure is evident when small sections of your pattern won't wash out, but everything around it does. This probably just means that there's a flaw in your positive that let the light through in that spot, and you need to go back and touch up the positive for next time.

Solving Over-Exposure
Unfortunately, there's not a whole lot you can do once you've over exposed a screen except deal with the imperfection (in the case of local over-exposure) or reclaim the screen and try again with the above things in mind. Don't give up right away though, over-exposure occurs by degrees, and just because it's harder than usual to wash out your pattern doesn't mean it's hopeless. Keep scrubbing and if it doesn't seem to be changing at all after a while, then you can probably assume it's over-exposed.

title: Screen Printing/Common Problems


text:
User talk:Cacace~enwikibooks

Economic Expansion In The Information Age is a living document. I fully expect that it will evolve as newe information is available. I welcome your comments, questions and suggestions.

Orphaned fair use
Hi Cacace, I noticed that you have uploaded a PDF file of a thesis, and listed it under fair use (Image:EconomicExpansion-Cacace-ss1-2b.pdf), and that it isn't linked to from anywhere. If you are the author of this thesis, I would highly suggest that you license it under a different license (a free license, like the GFDL) and link to it from somewhere in the project. If it is not, might I ask what permissions you have to post it here? If you don't have permissions this is probably not the best place to host the work. Please let me know. Regards, Mattb112885 (talk to me) 23:26, 24 July 2007 (UTC)
 * Hi Cacace, thank you for getting back to me. The recommendation is to dual-license it under the GFDL and a CC sharealike license (that's the first option on the drop-down list if I remember correctly). Your image was deleted since we generally don't like fair use files laying around (they're a legal liability especially if they're not being used). Just make sure you understand what the terms of the GFDL/CC are (basically, people can modify them and use them however they want, including selling it, as long as they give you credit; but you could do the same with anyone else's or with your own GFDL work as well) before deciding on this. Feel free to ask me or someone on the reading room (one of the assistance pages) who likely knows more about copyright than I do if you have any questions. Regards. Mattb112885 (talk to me) 20:54, 10 April 2008 (UTC)
 * Don't worry about creating orphan pages, I deleted the old one. Just upload it just like you did with the other file, except this time choose a different license. Be warned that it might get deleted anyways if it's original research (see the page defining this); if it is perhaps you would do better uploading it to wikiversity since they tend to focus more on that sort of thing. Regards Mattb112885 (talk to me) 19:53, 9 May 2008 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Cacace. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Cacace~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:04, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 04:44, 19 April 2015 (UTC)

title: User talk:Cacace~enwikibooks


text:
Greek Mythology/Gods/Poseidon

Poseidon (In Greek: Ποσειδῶν, known as Neptune to the Romans) was considered as the god of the ocean. Born of Chronos and Rhea, he had Zeus and Pluto (Hades) for brothers. Poseidon also had three sisters: Hestia, Hera, and Demeter. When Zeus overthrew their father, and the three brothers divided the earth among them, Poseidon became the god of the sea and earthquakes and thunder.

Origin of the Horse
When Poseidon desired Hestia, she asked Poseidon to create the world's most beautiful animal in an attempt to cool off his advances. As a result, Poseidon created the first horse and also became the God of horses. In some versions of this story, several other types of animals were created before the horse as a result of Poseidon's several unsuccessful attempts. By the time the horse was created, Poseidon's passion for Hestia had longed.

Symbolism
The symbol Poseidon is associated with is the trident, a weapon which can shake the Earth and shatter any object. Poseidon is often depicted sitting next to his wife, Amphitrite, in his sea chariot pulled by sea creatures.

title: Greek Mythology/Gods/Poseidon


text:
User:Cacace~enwikibooks

You may offer your comments or questions regarding any document that I have published on wiki or elsewhere. I may not have time to respond, but your input in always taken, and is important to my ability to make knowledgeable contributions.

title: User:Cacace~enwikibooks


text:
Screen Printing/Making the Stencil/Photo Emulsion

Frame Requirements

 * 17″ x 15″ x 3/4″ plywood (shirtboard)
 * 24″ x 7″ x 3/4″ plywood (clamp board)
 * 29″ long piece of 2×4 (beam)
 * (2) 24″ x 2 1/2″ x 3/4″ pine (clamps)
 * (2) eye screws
 * (2) carriage bolts 3/8″ x 3 1/2″
 * (2) washers 3/8″
 * (2) wing nuts 3/8″
 * strip hinge
 * wood screws
 * rubber bands
 * plastic zip tie

How To
One of the often preferred methods for making silk screening stencils is the photo emulsion technique. Photo emulsion is thick liquid substance which reacts to light. Essentially, photo emulsion becomes "tougher" when exposed to light, making it more difficult to remove from surfaces. That's perfect for creating a stencil: we'll "toughen" up parts of the stencil that we want to keep solid, and then wash away the rest.

Applying the Emulsion
The way we do this is to spread a thin layer of the emulsion over both sides of our screen. You can do this with either a "scoop coater" or a standard squeegee.

To clarify in this section, the "top" of the screen is the side that sits embedded in the wooden frame, and is the side from which you apply screen-printing ink. The "bottom" is the side where the screen is flush with the wood frame, and is placed side-down when printing.

Since you'll be applying the emulsion to both sides, you will need some temporary way of supporting the frame when it is side-down. Thumb tacks stuck into the corners of your frame work well for this. You could avoid this if you did the top first, and then the bottom, since the frame itself holds the top up off the surface, but you'll also want to dry the screen with the bottom side down, so you'll need to support it then, anyway.

Lay the screen flat, right side up, and pour a thin line of emulsion along one edge of the top side of your screen. Use smooth, even, and fairly light strokes of the squeegee to apply a smooth and even layer. Once the top side is coated, flip it over and repeat on the bottom. You'll want to make sure, therefore, that your squeegee fits inside the frame on the bottom side. It is best if it will fit going both the long way and the short way, but as long as it at least fits the long way, you should be ok. Note that after doing the top side, you'll probably have quite a bit of emulsion already pushed through the screen on the bottom side. That's fine, but you'll probably want to add more to the bottom side, still, to get a good coat.

Make sure to cover entirely both sides of the screen, any holes you leave will allow ink to get through. The edges are particularly prone to this, and will cause stray lines of ink to show up on your print. Do the best you can, and remember that on the bottom of the screen (the printing side, or flat side), you can extend the emulsion over the edge of the screen onto the frame, if that helps seal those edges.

Drying the Screen
Make sure you dry the screen in a dark location, exposing it to light now will cause over exposure and ruin your stencil. If you have a dark closet or drawer where you can lay it flat and it won't be disturbed, that's fine. Other alternatives are to fashion an opaque box big enough to fit the frame in. If you're handy with wood, you can make one yourself, or you can just get yourself some sort of rubber storage container big enough for the frame. Most such containers are fairly transparent, however, so you can get yourself some nice thick black paint and coat the thing in a few layers of that to black out the light. Coating the inside is the cleanest, but depending on the kind of paint, it might be prone to scratching from the frame. Basically anything that will allow it to lay flat without the screen coming in contact with anything, and will prevent light from getting to it will do. You should also make sure it won't be exposed to too much dust, dirt, etc. It'll probably be in there for a day or two, so keep that in mind, especially in closets and drawers.

Your screen will take varying amounts of time to dry, depending on the emulsion, the thickness of the coat you put on, and the air conditions. In general, you're probably looking at about one or two days. I can't imagine it being more than that. A small fan blowing gently across it can help speed things up if you can arrange that.

As long as you're careful not to let too much light in, you can check on it once in a while by peeking into the closet/drawer/box. If it looks dry, you can check it by very gently touching the screen. Do this on the edge where it's less likely to cause problems if it's not dry. If it's not dry, it'll be at least a little tacky. Once it's dry, it shouldn't feel sticky at all. Also keep in mind that the top of the screen will generally dry faster than the bottom; be sure to check both sides before removing.

Exposing the Screen
After we allow the emulsion to dry, we apply what's called a positive to the screen. That's positive, as opposed to a negative, like a camera negative. In a negative, all the colors are inverted, white is black, and black is white. For a positive, the colors are not inverted. For our purposes, it's a positive of the design we want to create the stencil for. In other words, we're creating a stencil which we will use to transfer a design onto our fabric (or whatever you're printing), so the positive should be dark anywhere you want the ink to be printed. The idea of the positive is to block light from getting to certain parts of the photo-sensitized screen. You can do this in anyway that gets the job done; if you want to print a circle, you can stick an opaque bowl upside down on the screen. More often, though, the positive is created on clear plastic, like acetate or a transparency, with a good opaque ink. We'll go into more details in "Positives".

With the positive in place, a large piece of glass that completely covers the pattern should be placed on top, to prevent the pattern from moving. Ensure there is no dust or dirt on the glass that may show up later as specks. Underneath the screen should be a black-non reflective material, or a piece of Styrofoam that will prevent light from bouncing up onto the underside of your screen, exposing the areas you don't want exposed.

Expose the photo-sensitized screen to light. Different photo emulsions require different exposures, but most can be done under a typical 60 watt incandescent light bulb in a few hours, with a makeshift reflector made out of a 10 or 12" pie pan. Stronger lights will require less time to develop, perhaps as little as 15 minutes depending on conditions. Using unfiltered UV black lights, it only takes 5 minutes. This is the recommended exposure chart for Speedball brand photo emulsion. Both of these charts apply only if you cut a hole in the center of a pie pan and place it on the socket before the recommended bulb, forming a reflector to reflect the light down on the screen. With a 150W Bulb, Clear Incandescent: Screen Size-Bulb Height---Exposure Time 8"x10"--12 inches-45 minutes 10"x14"-12 inches-45 minutes 12"x18"-15 inches-1 hr. 14 minutes               16"x20"-17 inches-1 hr. 32 minutes 18"x20"-17 inches-1 hr. 32 minutes With a BBA No. 1 Photoflood (250 watts): Screen Size-Bulb Height---Exposure Time 8"x10"--12 inches-10 minutes 10"x14"-12 inches-10 minutes 12"x18"-15 inches-16 minutes 16"x20"-17 inches-20 minutes 18"x20"-17 inches-20 minutes

Developing the Pattern
Once the screen is properly exposed, you can remove it from the immediate light source and remove the positive. As soon as the positive is removed, you should start washing it out (under normal indoor lighting conditions, most emulsions won't develop in a matter of minutes while you're getting to the sink, etc., but don't dawdle too much, and certainly don't remove the positive, and plan to come back to wash out the screen at another time). This is done under regular tap water, nothing special required. If the screen was exposed properly, the unexposed portions should begin to become visible almost immediately under a strong flow of water, and a little vigorous scrubbing with your finger tips will have it fully removed in 10 to 15 minutes, or so. Once the stencil is totally washed out and allowed to dry, you've got yourself a stencil, perfect for screen printing.

Positives
A good positive can be made with dark ink on a sheet of transparent plastic. The two basic methods for this are by hand, and by machine.

The Ink
Doing it by hand is probably the most accessible, but it can also be a real head ache. One of the first issues you'll face is getting a good ink. It is possible to produce a viable positive with permanent marker, but it will probably require double siding (see below) and it's more difficult to work with than some other alternatives, such as India ink. India ink is a rich dark ink, and is relatively quick drying. You can get India ink pens at most art stores in a variety of sizes, for probably around a dollar or two (US$) per pen. This is my preferred method for hand producing positives, but it's still a lot of work. I recommend you get yourself a bold pen, as well as a super fine. Different brands may mark this differently, but bold is generally about as thick as a standard Sharpie marker, and super fine is a about the size of mechanical pencil lead. If you're stocking up, you'll probably want more bold and super fine; if you're doing that much detailed work that you're going to go through the super fines fast, then you might want to think about skipping down to the next section. If it's available in multiple colors, black should be your first choice, since it will block the most light. You might also want to get one of each size in another dark color, such as dark blue or brown. This is useful for double siding, as I'll explain more below.

The Transparency
Once you've got the ink, you need something to put it on. I recommend acetate, which you can probably buy at an art store in a little pad, like a sketch pad except with acetate instead of paper. If it's not acetate, it shouldn't matter, the only real requirement is that it be transparent, and that you can write on it with your ink. Some materials may accept the ink better than others. In my own experience, I've found that India ink on acetate never fully dries, and is therefore prone to smudging and rub offs. On the other hand, this can be a good thing as it's relatively easy to erase with a the tip of your finger, maybe slightly moistened. You'll probably run into similar problems with pretty much any combination of drawing ink and plastic, but some may be better than others, just experiment as you prefer, or ask someone more knowledgeable about plastics and inks.

The Pattern
Ok, ink, transparency, check. But you still need to get the ink on the transparency, preferably in the shape of your intended pattern. The artistic type might choose to draw free hand on the acetate, but more likely you'll be tracing. Even if you want to draw the image yourself, it's probably better to do it with pencil on paper, first, then trace it onto acetate. For the non-artistic type, the image can come from anywhere you can think of. A simple graphics program (or a complex graphics program, if you prefer) can be used to generate some great mono color images that you can then print onto plain paper. Just remember, however many colors you print, each stencil is monochromatic, so your prints will be too. If you want to try multi-color printing, read this section, but I'd recommend you start with simple one-color prints first.

Also remember that you're going to be able to see right through the acetate onto the original image once you're tracing. This can make it difficult to see where you have and haven't already traced, especially if your image is the same color as your tracing ink (which is common if you're using black ink and printing images from a computer). To help this, consider making your images a different, probably lighter, color than your tracing ink. This will make it easier to tell the difference between your traced image, and the original image.

The only thing I have to say about getting the image is to keep copyrights in mind. If you're going to be selling your prints, don't use any copyrighted or trademarked material without permission of the owner. Even if you're not selling, you may want to check local laws about copyright infringement before using any such materials.

Tracing
Once you've got the image, tracing is simple (in theory) since the sheet is transparent, just tape the image you want to trace to the back of the transparency, and have at it. As I said, this can be a real headache. You don't have a very precise eraser while doing this, and making precise marks with a bold tipped wet-ink pen can be a challenge. Fine tipped pens may help you be more precise, but they also tend to not apply quite as well, the tip is usually more firm than with a bolder pen, and tends to rub off ink you've already put down (which, incidentally, is the same problem you might face with a permanent marker). But a fine tip is good for doing outlines and fine details, and use the bolder pen to fill in larger areas. If you really want to go all out, get yourself some in between sizes, as well to help fill in thick lines, or thin spaces. Just remember, however quick drying the pen claims to be, it probably isn't meant for plastic, and probably won't dry all that quick, if ever, so be careful about smudging. You'll typically want to work left to right for right handers (and right to left for left handers), and then top to bottom, so you don't accidentally smudge your earlier work with your hand, wrist, arm, or what have you.

Double Siding
When you've finished tracing or otherwise producing your image on the transparency, remove the original image from the back and hold the transparency up to the light. You'll probably notice that quite a bit of light still comes through the ink, and you may even notice places where you didn't trace at all, or where the ink got completely rubbed off. All of these little imperfections can cause trouble when you're exposing your screen, because if too much light gets through, the emulsion will set and you won't be able to wash it off, which means your stencil will have little marks where the ink doesn't go through when it's time to print. You can fix these up when you spot them, but it can be difficult to find them all, and there's always a chance that it'll get rubbed off again before you print. I've found that the best way to deal with this is a process I call double siding, which simply means you retrace the image on the reverse side of the transparency. The idea is that if there's a small imperfection in the image on one side, there's a slim chance that there will be one in the same spot on the other side, you at least you've got a good fighting change. Furthermore, double siding basically doubles the opacity of your image, blocking out more light. This is very useful if you've found yourself prone to over exposure.

Of course, double siding does produce it's own little set of hassles. For one thing, all that work you did tracing the image, you've got to do it all over again. Second, you've get ink all over what is now going to become the back side of the sheet. You've got to be very careful not to smudge it too much, or rub it clean off. Remember, though, the image is already there, you don't have to trace from the original again, so a good defense against smudging is to tape a sheet of white paper over your first trace, so that as you're tracing the back side, the wet ink will be somewhat protected. It's not perfect, though, you can still smudge even like that. Fortunately, you're double siding so smudging isn't as big of a concern. Lastly, remember how I said it can be hard to distinguish the original from your trace if the colors are too similar? The same goes for double siding. If you're using the same ink on the back as you did on the front, it can be even more difficult to tell what you've already re-traced. holding the image up to the light can be helpful for seeing this, but what a hassle. An alternative, as I mentioned briefly above, is to use two different colored inks for the front trace and the back trace, this will make it easier to tell the difference but remember, the whole point of double siding is to block out more light, so you have to make sure both inks are relatively opaque.

Saving Positives
You may likely want to save your positives once you're done with them. Especially if you're planning to reclaim the screen, you might want to recreate the stencil later, and you certainly wouldn't want to have to go through all that again. Unfortunately, the ink on plastic problem can get in the way of this, so just be real careful about storing them, don't put them somewhere that they're likely to be shuffled around a lot, or have things set on top of them. There are probably ways of treating them to make them more permanent, or even to coat them with something. Go to your local art store or hobby store and see if they have any suggestions. Just remember: the whole point is to block light from the inked spots, and let light through the rest, so don't do anything that's going to conflict with that, for instance some kind of varnish that clouds up when it dries and blocks a lot of light from getting through.

By Machine
This isn't as intimidating as it may sound. Machine in this case just means a computer and printer, or a photocopier. The idea is to simply use one of these devices to print your pattern directly onto a transparency.

Office supply stores usually sell transparencies designed to work with various printers. You want to use the correct transparencies/acetate with laser printers, if you use a regular acetate, it will melt in the printer. This is a low quality method to create film positives.

Good quality film positives can be obtained by using ink-jet printers. If you combine a dye ink Epson printer such as the Epson Stylus 2400 with the correct films such as AccuBlack or AccuArt the results are fine for commercial screen printing. For good results you are looking for high opacity and a high contrast between the film and the ink laid down.

Alternatively, many copy shops should be able to copy a pattern onto a transparency. This may be quick but the opacity is low. Between laser printers or paying a copy house to do it, I don't know which is more expensive in the long run.

Which ever you choose to use, make sure the image is going to block out enough light. Typically, this kind of printing or copying is intended for over head projectors which don't actually require very opaque images. You can try printing a sample to see how opaque it is. If you've done a lot of photo emulsion stenciling, you can probably get a good idea just by looking at it against the light of whether or not it's dark enough. If you're not sure, you can experiment with it, and just be prepared to waste the stencil if it's not dark enough, or you can maybe waste a little money and play it safe. There's a few things you can do to make it more opaque. First, if you're at a copy shop, ask the clerk for suggestions, they may have special toners that are more opaque, and they can probably increase the contrast to make a darker image. If you're printing at home, you can play with your printer settings to try making the image darker. An alternative for either copier or printer is to do double copies of all your positives, and just make sure they're well lined up before using them on your screen. You can use clear acetate desk tape to fold them together since it won't block any extra light. You just have to be real sure you get them lined up right or your image will end up kind of funny. You could also increase opacity by "double siding" a machine printed original, as described above.


text:
Greek Mythology/Gods/Hephaestus

Haphaestus was the god of fire and smithing, forger of great weapons and devices. Among these, the golden dogs of Alconoo, the Aetan bulls, the golden maidens that served him, and Pandora, the first woman.

Haphaestus was lame and considered the ugliest of the gods, but his skill and prowess at the forge was renowned. Aphrodite became his wife, but she would often be unfaithful.

Hephaestus was the son of Zeus and Hera (of Hera alone according to some versions). The Roman equivalent is Vulcan.

title: Greek Mythology/Gods/Hephaestus


text:
Greek Mythology/Gods/Dionysus

Dionysus, in contrast to Apollo, was the god of wine, theatre and revelry. A son of Zeus. The Romans called him Bacchus. Dionysus was a happy god, often associated with feasts and merriment, and his worship became very popular.

title: Greek Mythology/Gods/Dionysus


text:
Greek Mythology/Gods/Hera

Hera was the sister and wife of Zeus. She was raised by Ocean and Tethys. Considered as a guardian of women and goddess of marriage, she was stern and jealous, and often angry because of her husband's numerous affairs with other women. Most stories about Hera describe her acts of revenge for her husband's infidelities.

The deceitful way Zeus tricked Hera into marrying him was an omen of the discord that continued throughout their marriage. After courting Hera to no avail, Zeus resorted to trickery by changing into a disheveled cuckoo. Hera took pity on the bird, holding it to her breast to keep it warm. Zeus then reverted to his normal form, and took advantage of Hera's surprise by raping her. Hera then married Zeus as a way to hide her shame.

Hera's sacred animals are the cow and the peacock. Argos is Hera's favorite city.

Hera sliced off her hand to please Zeus and to make him stop having affairs with other women / goddesses.

title: Greek Mythology/Gods/Hera


text:
Greek Mythology/Gods/Hermes

Hermes was the god of merchants and traveling, and he was often depicted with a helmet and sandals with wings, and carrying a caduceus. Sly but well-intentioned, he was also the messenger of the gods, and he would often be entrusted with delivering messages to mortals on their behalf. The Roman equivalent is Mercury.

title: Greek Mythology/Gods/Hermes


text:
Greek Mythology/Beasts/Pegasus

Pegasus was the winged horse on which Bellerophon rode when slaying the Chimaera. It was said he could not be ridden without a special bridle, which Bellerophon acquired with the help of Athena. Before being tamed, Pegasus lived on Mount Helicon with the Muses.

Pegasus was the son of Medusa and Poseidon, springing fully-grown from his mother's neck after she was beheaded by Perseus. Pegasus had been conceived before Medusa was changed into a Gorgon.

When Bellerophon tried to fly to Mount Olympus, Zeus caused Pegasus to rear back, throwing off its rider back down to Earth. Zeus then used Pegasus to carry Zeus' thunderbolts, for which Pegasus was rewarded with a constellation.

title: Greek Mythology/Beasts/Pegasus