text:
The Computer Revolution/Hardware/Computer case

Power supply
The computer's power supply unit (PSU) turns the mains voltage (110 V or 240 V alternating current) into the different direct current voltages required by the computer's components.

For personal computers, there are three types of PSU still in use: AT, ATX and ATX-2. ATX-2 is the most recent standard. AT is only in use in the oldest personal computers.

Bays
A bay is a shelf or an opening used for the installation of drives into the computer(Ex. Hard drive or DVD drive). A computer may come equipped with 4 to 8 bays, empty bays are covered by a panel.When the bay is accessible its open to the outside of the PC, and if its hidden its closed inside the PC case.

Optical Disks
CD-ROM (an abbreviation of "Compact Disc Read-Only Memory") is a compact disc that contains data accessible by a computer. While the compact disc format was originally designed for music storage and playback, the format was later adapted to hold any form of binary data. CD-ROMs are popularly used to distribute computer software, including games and multimedia applications, though any data can be stored. Some CDs hold both computer data and audio with the latter capable of being played on a CD player, whilst data is only usable on a computer. These are called Enhanced CDs. There are several formats used for data stored on compact discs, known collectively as the Rainbow Books. These include the original Red Book standards for CD audio, White Book and Yellow Book CD-ROM[1]. ISO 9660 defines the standard file system of a CD-ROM, although it is due to be replaced by ISO 13490. UDF format is used on user-writeable CD-R and CD-RW discs that are intended to be extended or overwritten. The bootable CD specification, to make a CD emulate a hard disk or floppy, is called El Torito

Other optical disk formats include DVD and Blu-Ray.

Motherboard
The Motherboard is a flat circuit board housed in the computer's case. Several indispensable computer components such as microprocessors chips, RAM chips,ROM chips, expansion slots, and co-processor slots operate from the motherboard, which according to the Using Information Technology text is akin to the central nervous system. It contains a number of components that are critical to the function of the computer.

Let's explore some of these components in more detail starting with the microprocessors or Central Processing Unit. CPU is the computer's brain. It converts data into information which tells the computer what to do. For example, when you left click on the Windows Explorer Icon on your desk top. This command is first sent to the CPU which relays a message telling the Windows Explorer Icon to open. Even simple actions like typing "A" on the key pad must be processed by the CPU before it can appear on your screen. Some of the leading microprocessor or microchip makers are, Intel,IBM, and Apple.

Random Access Memory or RAM is the main primary storage facility on you computer. It keeps information more readily accessible but stores it only temporarily.If your computer freezes or the power goes off, while you are working on a Word document for example, all your work will be lost. Thus, it is important to frequently save your work which will store your document in a secondary storage facility (hard drive) where it is retrievable even if your computer malfunctions.

ROM or Read Only Memory is a nonvolatile storage facility where information cannot be readily added or removed by the user with out special knowledge. Instructions like how to start the computer or where to put icons on the desktop are stored here. The manufacturer puts these instructions in the ROM when the computer is being assembled.

Flash Memory is nonvolatile memory that can be used by the computer or user. It can be erased electronically and rewritten. Most computers use flash memory for start-up instructions because it is easy to update. Flash memory is used in different portable devices such as mobile phones, digital cameras, portable digital media players and portable computers. Flash memory is also used in storage media such as flash memory cards and USB flash drives.

The motherboard also houses expansion slots which allow the user to expand the computers capabilities. If you want to add a video card, sound card, fax machine or printer, the connectivity for these devices is found on the motherboard. All things considered, clearly the motherboard is an indispensable component of the computer.


text:
The Computer Revolution/Hardware/Memory

=Types of Memory=

4 types of Memory

=1.RAM =

So what is RAM Memory?

Basically Ram, or random access memory, temporarily stores both software instruction and data. It is stored both before and after it is processed by the CPU. It is basically your computers short term memory.

RAM, is only temporarily memory, as it requires electricity to maintain the information stored in it. Hence, once the power is off the information is gone. Because of this, RAM is also been dubbed the Volatile storage area.

RAM is just like CPU, it also contains the electronic circuits etched onto chips, which in turn, are plugged to motherboard, hence called memory modules. Every computer is installed with different memory modules, like desktop and servers computer use dual in line memory modules whereas notebooks use small version memory modules namely small outline DIMM or SO-DIMM. In addition to that, many personal computers today are installed with two to four slots among them one will always be filled, but other slots are always available to install additional memory modules to it; to increase the performance of the computer.

Ram is measured in megabytes. Most computers today provide at least 256MB of RAM memory... of course this can be increased. The easiest way to tell if you overloading your RAM memory is to open several applications at the same time and run each. The response rate ( quickness) on how the applications respond from your inputs, will give you and idea of the amount of information your RAM can handle at any one time.... The more programs or applications running the slower the response.. Reason for this is that once the RAM becomes overloaded, the software will then start running applications off your hard drive which of course slows the overall performance of the computer.

There are 4 types of RAM Memory:

 * 1) DRAM - Dynamic RAM
 * 2) SDRAM - Synchronous Dynamic Ram
 * 3) SRAM - Static Ram
 * 4) DDR-SDRAM - Double date rate synchronous dynamic ram

By Kris Lobsinger

=2.ROM= ROM meaning Read-Only Memory is memory whose contents can be accessed and read but can't be changed. It is mainly used in computers but it is also used in other electronic devices. Since it can't really be written to, its main use is the distribution of Firmware. ROM is in the shape of a "computer chip". It can only be read with the exception of being written on once during the step called "programming". ROM's also cannot be erased or re-programmed. There are many different types of ROM including PROM's(Programmable Read-Only Memory). ROM is measured in Megabytes.

These nonvolatile chips are attached to the motherboard inside the system unit. ROM chips store the permanent instructions for the computer (also known as firmware) and the information stored here is retrieved as needed by the computer. Being nonvolatile, the information is not lost once the computer has been shut off.

ROM would include such things as the computer's BIOS (basic input/output system), which are the instructions the computer follows for booting up. It would also include directions for performing a POST (power-on self-test). Neither the BIOS nor the POST can be updated in traditional ROM. However, with the advent of flash memory and its replacing of traditional ROM, these operations can now be updated during the life of the device. References: Morley, Deborah and Charles Parker, Understanding Computers Today and Tomorrow, 13th Edition

=3.CMOS= Also known as a RTC/NVRAM or CMOS RAM, CMOS is short for Complementary Metal-Oxide Semiconductor. CMOS is an on-board semiconductor chip powered by a CMOS battery inside IBM compatible computers that stores information such as the system time and system settings for your computer. A CMOS is similar to the Apple Macintosh computer's PRAM.

Flash memory is the most common type of storage for portable devices such as digital cameras and phones. It can be used to transfer data from one device to another, and most computers today come with a flash memory card reader. Secure Digital (SD) is one of the most widely used flash memory media and it comes in different sizes. The standard size are generally used for cameras, and the miniSD and microSD are generally used for cell phones, and are about one quarter to one half the size of the standard SD card. There are adapters available for the smaller sized SD cards so they can be used in the standard flash memory card reader. The capacity for these cards is growing and is up to 4 GB for standard cards and 32 GB for high-capacity cards.

=4. Flash= Flash memory- is a form of non-volatile computer memory that can be electrically erased and reprogrammed.

Flash memory is available in 3 forms: 1. Flash memory card (aka RAM cards)- Removable storage media that is inserted into a flash memory port. It retains data when the power is turned off. 2. Flash memory sticks- Flash memory that plugs into a memory stick port which is very convenient to transport and use. 3. Flash Memory drives- finger sized module of flash memory that plugs into the USB ports of nearly any PC or Mac.

FUTURE OF RAM

As the ever quickening world of technology grows, new hardware is being demanded. RAM that we know now is volatile. When power is cut to the computer, data isn't retained in RAM. New methods are under development of nonvolatile RAM where data will continue to be held while no power is being supplied. Magnetic RAM is on the threshold of becoming very useful. It uses magnetic polarization to store information.

Flash memory is a nonvolatile chip that is used for storing items from a computer or from a user. This can also be easily erased and rewritten as often as needed. They are built into all types of technology devices, like cell phones, cameras, portable computers and IPods. Flash memory can come in different sizes. The most common GB people purchase is 1GB, 2GB, 4GB, 8GB, 16GB, and 32GB.

Flash Memory Drives or USB flash drives are a portable storage device that use a type of electronic memory called flash memory. Flash memory is referred to as solid-state, meaning that what makes it work is electronic and not mechanical. Flash drives can be used to back-up/store information such as text documents and pictures. They are compatible with a variety of devices from computers to digital cameras and even video game systems! Flash drives are a convenient and fairly inexpensive mode for storing information and allowing the user to take important data with them for use wherever they made need it.

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

title: The Computer Revolution/Hardware/Memory


text:
The Computer Revolution/Hardware/Ports

INFRA-RED Port
History:

The notion of infra-red was developed by Sir William Hersehel in the 1800's. The infra-red port is designed to communicate with other devices equipped with IRDA ports without the use of wires.

Examples of infra-red enabled devices include:
 * T.V.
 * VCR
 * PDA's
 * Laptops

Purpose of USB
USB was designed to be low cost and to be used in cheap devices like mice and game controllers with the ability to connect multiple USB devices and have faster speed and also easier to use with its capability of "plug and play", which allows you to remove the device while the PC is running.

The USB Connection and Its Standards
The newest version of USB is 2.0 and most of the PCs today have the 2.0 USB port. Older PC versions that have USB 1.1 will have to buy a 2.0 add-on upgrade to be able to hook up 2.0 USB devices. One of the benefits USB ports have is what is called a "daisy chain", or the ability to connect multiple USB devices to a single USB port on one computer. When more USB devices are needed a USB hub can be connected which enables the "daisy chain" to become very large. The problem with chaining too many devices is that the data signal weakens. There are some USB ports like modems, that are more efficient and transfer data faster when connected directly to the main USB port on the PC. Wireless USB technology was introduced in 2004 which can be very useful in home and office environments, because it ranges from 9 to 30 feet. Wireless USB products became available in 2006. Fire Wire is an analog of USB cable, designed and used on all products created by Apple Corp. This is a high-speed external connector that provides connection between a computer and peripheral devices. For the specialist is also known as IEEE 1394. Simply how it works. There are two kinds – backplane bus- rates are 12.5,25, or 50 MB per second and the cable interface – rates are 100, 200 or 400 MB per second. Fire Wire provides two types of f data transfer: asynchronous and isochronous. Asynchronous is for traditional load-and-store applications where data transfer can be initiated and an application interrupted as a given length of data arrives in a buffer. Isochronous data transfer ensures that data flows at a pre-set rate so that an application can handle it in a timed way. For multimedia applications, this kind of data transfer reduces the need for buffering and helps ensure a continuous presentation for the viewer. Comparing a similar Universal Serial Bus (USB) and Fire Wire could find a couple differences. USB is less expensive, but the data transfer is limited to 12 Mbps.

Dedicated
Dedicated ports are computer interface slots which are connected to a computers motherboard for the sole purpose of its defined application; other hardware needing uses to this port will earth have to be conformed of not use it at all. The most common applications are external: mouse and keyboards. The reverse of a general port.

SCSI
SCSI ports (pronounced "scuzzy") are for transmitting fast data to up to seven devices in a daisy chain. SCSI stands for "small computer system interface". Personal computers are able to communicate with hardware such as disk drives, tape drives, CD-ROM drives, printers and scanners much quicker. The current set of SCSIs are parallel interfaces that were developed at Apple Computer and are still used in the Macintosh today. SCSI ports continue to be built into PCs today, and as such, are supported by all major operating systems.

SCSI is also more flexible than previous parallel data transfer interfaces. Ultra-2 SCSI can transfer data up to eighty megabytes per second. Seven to fifteen devices can be connected to one SCSI port in the daisy-chain fashion, dependent on the bus width. One circuit board or card can accommodate all the peripherals.

The original SCSI is known as SCSI-1, which evolved into SCSI-2, also known as "plain SCSI" because it became widely accepted. SCSI-3 has extra specialized command sets that meet the needs of specific device types.

A SCSI standard is Ultra-2 which increases the burst rate up to 80 megabytes per second. It has a longer cabling distance of up to twelve meters because it uses low voltage differential signalling. This low voltage differential lowers power requirements and manufacturing costs.

The latest SCSI standard of Ultra-3 increases the burst rate from 80 megabytes per second to 160 megabytes per second. It does this by operating at the full clock rate as opposed to the half-clock rate of Ultra-2. Disk drives supporting Ultra-3 have faster data transfer rates. As well, Ultra-3 ensures the integrity of transferred data.

As we know, computer technology advances rapidly, and it is only a matter of time that a new SCSI standard of Ultra-4 is developed.

Enhanced
Specialized Expansion Ports

Ethernet is the most widely-installed local area network (LAN) technology. Ethernet was developed by the Xerox Corporation in 1970. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. The coaxial cable was later replaced with point-to-point links connected together by hubs and/or switches in order to reduce installation costs, increase reliability, and enable point-to-point management and troubleshooting. Ethernet is also used in wireless LANs.

The Infra-red Data Association, often referred to as IrDA, is a non-profit organization whose goal is to develop globally adopted specifications for infra-red wireless communication. IrDA was formed in 1994. IRDA is a port much like what you would find on your TV/VCR remote. This port allows two computers or a computer and a device to communicate amongst each other without the use of wires. For the devices to communicate via IrDA they must have a direct line of sight.

Musical Instrument Digital Interface (MIDI) ports are used to connect electronic musical instruments, computers, sound cards, samplers and other show equipment to exchange data. There are many different cables/connectors that are used to transport MIDI data between the devices. MIDI does not transmit audio, it simply transmits real time digital data.

Bluetooth ports consist of short-range radio waves that transmit up to 30 feet. It is used to connect cell phones to computers but also to connect computers to printers, keyboards, headsets, and other appliances. Bluetooth wireless technology simplify communication and synchronization between devices. It is a global standard that eliminates wires and cables between both stationary and mobile devices. It also facilitates both data and voice communication. It offers the possibility of ad hoc networks and delivers the ultimate synchronicity between all your personal devices.

FireWire ports speed up the movement of multimedia data and large files and enable easy connection of digital camcorders, cameras, digital video tapes/disks, PCs, TVs, printers and music systems directly to a personal computer. The connection enables simple, low-cost, high bandwidth realtime data interfacing. FireWire is Apple Computer's name for the IEEE 1394 High Speed Serial Bus. FireWire is similar to a USB port, but much more powerful. Users can transfer images with no image degradation.

The original FireWire was faster than a USB when it first debuted. The initial FireWire had transfer rates of up to 400Mbps. The difference between FireWire and USB are that FireWire are built for devices that work with a lot of data i.e audio equipment. FireWires can connect up to 63 devices. Firewire devices are known as hot pluggables, which mean they can be connected and disconnected at any time. FireWire devices allow devices to draw their power from their connection. The latest version of FireWire cables use a 9 pin configuration but some Firewire devices use 4 pin configurations to save space. Today FireWire cables can achieves speeds up to 800 Mbps. http://computer.howstuffworks.com/firewire4.htm

Definition
According to authors William and Sawyer the definition of a parallel port is equal to 8 bits (1 byte). Below is a picture of what a parallel port looks like.

Often a parallel port will be used for connected a printer to the computer. A parallel port is beginning to be phased out and USB is taking over what a parallel port once did.

Serial Ports
A serial port is considered to be one of the most basic external connectors on the computer. It is a connector for a line that sends bits one after another. Serial ports are usually used to connect peripheral devices such as keyboards, monitors, and modems because they do not require fast transmission of data. A serial port is also useful for sending data over a long distance.

External SATA ports
eSATA ports are used most commonly with external hard drives. The connection through the port is much faster than it a USB or FireWire port. The reason for the faster speed is because eSATA does not have to translate the data between the computer and the interface. When using a USB or FireWire port, the data must be translated before the command can be executed. This characteristic also translates to less lag during the connection process when using an eSATA port. An eSATA port provides a signal for the external devices, but not power; therefore, the device does need its own power supply. The connector cables are much narrower than some used with much older technology. Resources: http://www.wisegeek.org/what-is-esata.htm http://port16.com/blog/2007/11/01/what-is-esata/

title: The Computer Revolution/Hardware/Ports


text:
Wikijunior:The Elements/Periodic Table

What is the Periodic Table of Elements?
Although scientists know of many elements, the properties of many of them are similar. Thus if they are grouped on the basis of their properties, it becomes easy to study and compare their properties. The periodic table of elements is a way of organising all the known elements. In the early days, elements were classified into only two groups: metals and non-metals. But some elements showed the properties of both metals and non-metals. They were called as metalloids.

Early History
People have known about basic chemical elements such as gold, silver, and copper from antiquity, as these can all be discovered in nature in native form and are relatively simple to mine with primitive tools. Aristotle, a philosopher, theorised that everything is made up of a mixture of one or more of four elements. They were earth, water, air, and fire. This was more like the four states of matter (in the same order): solid, liquid, gas, and plasma, though he also theorised that they change into new substances to form what we see.

Hennig Brand was the first person to discover a new element. Brand was a bankrupt German merchant who was trying to discover the Philosopher's Stone — a mythical object that was supposed to turn inexpensive base metals into gold. He experimented with distilling human urine until in 1669 he finally obtained a glowing white substance which he named phosphorus. He kept his discovery secret, until 1680 when Robert Boyle rediscovered it and it became public.

By 1809, a total of 47 elements had been discovered. As the number of known elements grew, scientists began to recognize patterns in the way chemicals reacted and began to devise ways to classify the elements.

Antoine-Laurent de Lavoisier
Antoine Lavoisier's Traité Élémentaire de Chimie (Elementary Treatise of Chemistry, 1789, translated into English by Robert Kerr) is considered to be the first modern chemical textbook. It contained a list of elements, or substances that could not be broken down further, which included oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulfur. It also forms the basis for the modern list of elements. His list, however, also included light and caloric, which he believed to be material substances. While many leading chemists of the time refused to believe Lavoisier's new revelations, the Elementary Treatise was written well enough to convince the younger generation.

This model only classified elements into metals and non-metals and thus was not accepted.

Alexandre-Emile Béguyer de Chancourtois
Alexandre-Emile Béguyer de Chancourtois, a French geologist, was the first person to notice the periodicity, the periodic or repetitive nature, of the elements — similar elements seem to occur at regular intervals when they are ordered by their atomic weights. He devised an early form of periodic table, which he called the telluric helix. With the elements arranged in a spiral on a cylinder by order of increasing atomic weight, de Chancourtois saw that elements with similar properties lined up vertically. His chart included some ions and compounds in addition to elements. His paper was published in 1862, but used geological rather than chemical terms and did not include a diagram; as a result, it received little attention until the work of Dmitri Mendeleev.

John Newlands
John Newlands was an English chemist who in 1863 classified the 56 elements that had been discovered at the time into 11 groups which were based on similar physical properties. He noted that many pairs of similar elements existed which differed by some multiple of eight in atomic weight.

The first periodic table

Dmitri Mendeleev, also spelt Dmitry Mendeleyev, middle name (patronymic) Ivanovich, a Siberian-born Russian chemist, was the first scientist to make a periodic table much like the one we use today. Mendeleev arranged the elements in a table ordered by atomic mass. It is sometimes said that he played "chemical solitaire" on long train rides using cards with various facts of known elements. On March 6, 1869, a formal presentation was made to the Russian Chemical Society, entitled The Dependence Between the Properties of the Atomic Weights of the Elements. His table was published in an obscure Russian journal but quickly republished in a German journal, Zeitschrift für Chemie, in 1869. It stated

 * 1) The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.
 * 2) Elements which are similar as regards to their chemical properties have atomic weights which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs).
 * 3) The arrangement of the elements, or of groups of elements in the order of their atomic weights, corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, Ba, C, N, O, and Sn (probably an error for Li, Be, B, C, N, O and F, since the symbols for the elements weren't completely standardized yet at that time).
 * 4) The elements which are the most widely diffused have small atomic weights.
 * 5) The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.
 * 6) We must expect the discovery of many yet unknown elements–for example, elements analogous to aluminium and silicon–whose atomic weight would be between 65 and 75.
 * 7) The atomic weight of an element may sometimes be amended by a knowledge of those of its contiguous elements. Thus the atomic weight of tellurium must lie between 123 and 126, and cannot be 128.
 * 8) Certain characteristic properties of elements can be foretold from their atomic weights.

Advantages
 * Mendeleev predicted the discovery of other elements and left space for these new elements, namely eka-silicon (germanium), eka-aluminium (gallium), and eka-boron (scandium). Thus, there was no disturbance in the periodic table.
 * He predicted (often accurately as it turned out) properties of some of these then missing elements as well as properties of some of their compounds.
 * He pointed out that some of the then current atomic weights were incorrect.
 * He provided for variance from atomic weight order

Drawbacks
 * There was no place for the isotopes of the various elements.
 * His table did not include any of the noble gases, which hadn't been discovered. But these were added by Sir William Ramsay as Group 0, without any disturbance to the basic concept of the periodic table.

Unknown to Mendeleev, Lothar Meyer was also working on a periodic table. In his work published in 1864, Meyer presented only 28 elements, classified not by atomic weight but by valence alone. Also, Meyer never came to the idea of predicting new elements and correcting atomic weights. Only a few months after Mendeleev published his periodic table of all known elements (and predicted several new elements to complete the table, plus some corrected atomic weights), Meyer published a virtually identical table. Some people consider Meyer and Mendeleev the co-creators of the periodic table, although most agree that Mendeleev's accurate prediction of the qualities of the undiscovered elements lands him the larger share of credit. In any case, at the time Mendeleev's predictions greatly impressed his contemporaries and were eventually found to be correct. An English chemist, William Odling, also drew up a table that is remarkably similar to that of Mendeleev in 1864.

Henry Moseley
In 1914, Henry Moseley found a relationship between an element's X-ray wavelength and its atomic number and therefore resequenced the table by electronic charge rather than atomic weight. Before this discovery, atomic numbers were just sequential numbers based on an element's atomic weight. Moseley's discovery showed that atomic numbers had an experimentally measurable basis.

Moseley's research also showed that there were gaps in his table at atomic numbers 43 and 61 which are now known to be radioactive and not naturally occurring. Following in the footsteps of Dmitri Mendeleyev, Henry Moseley also predicted new elements.

Glenn T. Seaborg
During his Manhattan Project research in 1944, Glenn T. Seaborg experienced unexpected difficulty isolating Americium (95) and Curium (96). He began wondering if these elements more properly belonged to a different series which would explain why the expected chemical properties of the new elements were different. In 1945, he went against the advice of colleagues and proposed a significant change to Mendelev's table: the actinide series.

Seaborg's actinide concept of heavy element electronic structure, predicting that the actinides form a transition series analogous to the rare earth series of lanthanide elements, is now well accepted in the scientific community and included in all standard configurations of the periodic table. The actinide series are the second row of the f-block (5f series) and comprise the elements from Actinium to Lawrencium. Seaborg's subsequent elaborations of the actinide concept theorized a series of superheavy elements in a transactinide series comprising elements 104 through 121 and a superactinide series inclusive of elements 122 through 153.

title: Wikijunior:The Elements/Periodic Table


text:
A-level Mathematics/OCR/C3/Formulae

By the end of this module you will be expected to have learnt the following formulae:

Reflection

 * 1) $$y = -f \left (x \right )\,$$ is a reflection of $$y = f \left (x \right )\,$$ through the x axis.
 * 2) $$y = f \left (-x \right )\,$$ is a reflection of $$y = f \left (x \right )\,$$ through the y axis.
 * 3) $$y = \begin{vmatrix}f\left(x\right)\end{vmatrix}$$ is a reflection of $$y = f \left (x \right )\,$$ when y < 0, through the x-axis.
 * 4) $$y =f\left(\begin{vmatrix}x\end{vmatrix}\right)$$ is a reflection of $$y = f \left (x \right )\,$$ when x < 0, through the y-axis.
 * 5) $$y = f^{-1} \left (x \right )\,$$ is a reflection of $$y = f \left (x \right )\,$$ through the line y = x. Note: $$f^{-1} \left (x \right )$$ exists only if $$f \left (x \right )$$ is bijective, that is, one-to-one and onto.

Stretching

 * 1) $$y = af \left (x \right )\,$$ is stretched toward the x-axis if $$0 < a < 1\,$$ and stretched away from the x-axis if $$a > 1\,$$. In both cases the change is by a units.
 * 2) $$y = f \left (bx \right )\,$$ is stretched away from the y-axis if $$0 < b < 1\,$$ and stretched toward the y-axis if $$b > 1\,$$. In both cases the change is by b units.

Translations

 * 1) $$y = f \left (x - h \right )\,$$ is a translation of f(x) by h units to the right.
 * 2) $$y = f \left (x + h \right )\,$$ is a translation of f(x) by h units to the left.
 * 3) $$y = f \left (x \right ) + k\,$$ is a translation of f(x) by k units upwards.
 * 4) $$y = f \left (x \right ) - k\,$$ is a translation of f(x) by k units downwards.

Natural Functions

 * 1) $$e^{\ln x} = \ln e^x = x\,$$
 * 2) $$y\left(t\right)=y_0e^{kt}\,$$, where y(t) is the final value, $$y_0$$ is the initial value, k is the growth constant, t is the elapsed time.
 * 3) $$k = - \frac {\ln 2}{half-life}$$, k for calculations involving half-lives.

Reciprocal Trigonometric Functions and their Inverses

 * $$ \sec \theta \equiv \frac{1}{\cos \theta}$$
 * $$ \operatorname{cosec}\ \theta \equiv \frac{1}{\sin \theta}$$
 * $$ \cot \theta \equiv \frac{1}{\tan \theta}\equiv \frac{\cos \theta}{\sin \theta}$$
 * $$ \sec ^2 \theta \equiv 1 + \tan ^2 \theta$$
 * $$ \operatorname{cosec} ^2\ \theta \equiv 1 + \cot ^2 \theta$$

Angle Sum and Difference Identities
Note: The sign $$\mp$$ means that if you add the angles (A+B) then you subtract in the identity and vice versa. It is present in the cosine identity and the denominator of the tangent identity.
 * $$\sin(A \pm B) = \sin(A) \cos(B) \pm \cos(A) \sin(B)\,$$
 * $$\cos(A \pm B) = \cos(A) \cos(B) \mp \sin(A) \sin(B)\,$$
 * $$\tan(A \pm B) = \frac{\tan(A) \pm \tan(B)}{1 \mp \tan(A)\tan(B)}$$

Double Angle Identities

 * $$ \sin 2A \equiv 2 \sin A \cos A$$
 * $$ \cos 2A \equiv \cos ^2 A - \sin ^2 A \equiv 1 - 2\sin ^2 A \equiv 2\cos ^2 A - 1$$
 * $$ \tan 2A \equiv \frac{2 \tan A}{1 - \tan ^2 A}$$

Combination of Trigonometric Functions
Using radians r = amplitute α = phase. $$r = \sqrt{a^2+b^2}$$

 * $$a\sin x+b\cos x=r\cdot\sin(x+\alpha)\,$$

where
 * $$\alpha = \arcsin\frac{b}{r}$$

$$a\sin x+b\cos x=r\cdot\cos(x-\alpha)\,$$

where
 * $$\alpha = \arccos\frac{b}{r}$$

Differentiation

 * If $$ y = \operatorname{e}^{kx}\,$$, then $$ \frac{dy}{dx} = k\operatorname{e}^{kx} $$
 * If $$ y = \ln x\,$$, then $$ \frac{dy}{dx} = \frac{1}{x} $$
 * If $$ y = f(x).g(x)\,$$, then $$ \frac{dy}{dx} = f^'(x)g(x) + g^'(x)f(x)$$
 * If $$ y = \frac{f(x)}{g(x)}$$, then $$ \frac{dy}{dx} = \frac{f^'(x)g(x) -g^'(x)f(x)}{\left\{g(x)\right\}^2} $$
 * $$ \frac{dy}{dx} = \frac{1}{\frac{dx}{dy}}$$
 * If $$ y = f[g(x)]\,$$, then $$ \frac{dy}{dx} = f^'[g(x)].g^'(x)$$
 * $$ \frac{dy}{dt} = \frac{dy}{dx}.\frac{dx}{dt}$$

Integration
For volumes of revolution:
 * $$ \int \operatorname{e}^{kx}\, dx = \frac{1}{k}\operatorname{e}^{kx} + c $$
 * $$ \int \frac{1}{x}\, dx = \ln \left|x\right| + c$$
 * $$ V_x = \pi \int_{a}^{b} y^2\, dx$$
 * $$ V_y = \pi \int_{c}^{d} x^2\, dy$$

Numerical Methods
Simpson's Rule $$\int^b_a y dx \approx \frac{1}{3}h\left\{\left(y_0 + y_n\right) + 4\left(y_1 + y_3 + \ldots + y_{n-1}\right) + 2\left(y_2 + y_4 + \ldots + y_{n-2}\right) \right\}$$

where$$h = \frac{b-a}{n}$$ and n is even

title: A-level Mathematics/OCR/C3/Formulae


text:
Nanotechnology/Perspective

=A perspective on Nanotechnology= Nanotechnology in the Middle Ages?

The Duke TIP eStudies Nanotechnology course will be adding more to this section (this will be completed by 22 Jun 08)

One of the first uses of nanotechnology was in the Middle Ages. It was done by using gold nanoparticles to make red pigments in stained glass showing that nanotechnology has been around for centuries. The gold when clumped together appears gold, but certain sized particles when spread out appear different colors. Reference: The Nanotech Pioneers Where are they taking us? By Steven A Edwards

In the year 1974 at the Tokyo Science University, Professor Norio Taniigrichi came up with the term nanotechnology.

Nanotechnology was first used to describe the extension of traditional silicon machining down into regions smaller than one micron (one millionth of a meter) by Tokyo Science University Professor Norio Taniguchi in 1974. It is now commonly used to describe the engineering and fabrication of objects with features smaller than 100 nanometers (one tenth of a micron).

Nanotechnology has been used for thousands of years, although people did not know what they were doing. For example, stained glass was the product of nanofabrication of gold. Medieval forgers were the first nanotecnologists in a sense, because they, by accident, found out a way to make stained glass.

Reference Nanotechnology A GENTLE INTRODUCTION TO THE NEXT BIG IDEA By Mark Ratner & Daniel Ratner

In 2001, the federal government announced the National Nanotechnology Intiative to coordinate the work of different U.S. agencies and to provide funds for research and accelerate development in nanotechnology. This was spearheaded by Mahail Roco and supported by both president Clinton and Bush.

References The Nanotech Pioneers Where are they taking us? By Steven A. Edwards http://www.nano.gov/html/about/docs/20070521NNI_Industrial_Nano_Impact_NSTI_Carim.pdf

A Vision

Richard Feynman was a man of great importance to the field of nanotechnology. He was a man with a vision. He believed that with research we could change things on a small scale. In his famous speech There's Plenty of Room at the Bottom in 1959, Richard Feynman discussed the possibility of manipulating and controlling things on a molecular scale in order to achieve electronic and mechanical systems with atomic sized components. He concluded that the development of technologies to construct such small systems would be interdisciplinary, combining fields such as physics, chemistry and biology, and would offer a new world of possibilities that could radically change the technology around us.

Miniaturization

A few years later, in 1965, Moore noted that the number of transistors on a chip had roughly doubled every other year since 1959, and predicted that the trend was likely to hold as each new generation of microsystems would help to develop the next generation at lower prices and with smaller components. To date, the semiconductor industry has been able to fulfill Moore's Law, in part through the reduction of lateral feature sizes on silicon chips from around 10 micrometers in 1965 to 45-65 nm in 2007 via changing from the use of optical contact lithography to deep ultraviolet projection lithography.

In 1974 in Japan, Norio Taniguchi coined the word "nano-technology" to describe semiconductor processes such as thin film deposition and ion beam milling exhibiting characteristic control on the order of a nanometer: "‘Nano-technology’ mainly consists of the processing of separation, consolidation, and deformation of materials by one atom or one molecule."

Since Feynman's 1959 speech the arts of "seeing" and "manipulation" at the nanoscale have progressed from transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to various forms of scanning probe microscopy including scanning tunneling microscopy (STM) developed by Binnig and Rohrer at IBM Zurich and atomic force microscopy (AFM) devloped by (Binnig and Quate?) The STM, in particular, is capable of single-atom manipulation on conducting surfaces and has been used to build "quantum corrals" of atoms in which quantum mechanical wave function phenomena can be discerned. These atomic-scale manipulation capabilities prompt thoughts of building up complex atomic structures via manipulation rather than traditional stochastic chemistry. (Note: this pragraph is still rough and references are needed.)

Motivated by Feynman’s beliefs building things nanoscale top-down, Eric Drexler devoted much of his research to making a universal assembler. The American engineer Eric Drexler has speculated extensively about the laboratory synthesis of machines  at the molecular level via manipulation techniques, emulating biochemistry and producing components much smaller than any microprocessor via techniques which have been called molecular nanotechnology or MNT.

Successful realization of the MNT dream would comprise a collection of technologies which are not currently practical, and the dream has resulted in considerable hyperbolic description of the resulting capabilities. While realization of these capabilities would be a vindication of the hype associated with MNT, concrete plans for anything other than computer modeling of finished structures are scant. Somehow, a means has to be found for MNT design evolution at the nanoscale which mimics the process of biological evolution at the molecular scale. Biological evolution proceeds by random variation in ensemble averages of organisms combined with culling of the less-successful variants and reproduction of the more-successful variants, and macroscale engineering design also proceeds by a process of design evolution from simplicity to complexity as set forth somewhat satirically by John Gall: "A complex system that works is invariably found to have evolved from a simple system that worked. . . . A complex system designed from scratch never works and can not be patched up to make it work. You have to start over, beginning with a system that works." A breakthrough in MNT is needed which proceeds from the simple atomic ensembles which can be built with, e.g., an STM to complex MNT systems via a process of design evolution. A handicap in this process is the difficulty of seeing and manipulation at the nanoscale compared to the macroscale which makes deterministic selection of successful trials difficult; in contrast biological evolution proceeds via action of what Richard Dawkins has called the "blind watchmaker" comprising random molecular variation and deterministic survival/death.

Technological development and limits

The impact on society and our lives of the continuous downscaling of systems is profound, and continues to open up new frontiers and possibilities. However, no exponential growth can continue forever, and the semiconductor industry will eventually reach the atomic limit for downsizing the transistor. Atoms in solid matter are typically one or two hundred picometers apart so nanotechnology involves manipulating individual structures which are between ten and ten thousand atoms across; for example, the gate length of a 45 nm transistor is about 180 silicon atoms long. Such very small structures are vulnerable to molecular level damage by cosmic rays, thermal activity, and so forth. The way in which they are assembled, designed and used is different from prior microelectronics.

New ways

Today, as that limit still seems to be some 20 years in the future, the growth is beginning to take new directions, indicating that the atomic limit might not be the limiting factor for technological development in the future, because systems are becoming more diverse and because new effects appear when the systems become so small that quantum effects dominate. The semiconductor devices show an increased diversification, dividing for instance processors into very different systems such as those for cheap disposable chips, low power consumption portable devices, or high processing power devices. Microfabrication is also merging with other branches of science to include for instance chemical and optical micro systems. In addition, microbiology and biochemistry are becoming important for applications of all the developing methods. This diversity seems to be increasing on all levels in technology and many of these cross-disciplinary developments are linked to nanotechnology.

Diversification

As the components become so small that quantum effects become important, the diversity will probably further increase as completely new devices and possibilities begin to open up that are not possible with the bulk materials of today's technology.

The nanorevolution?

The visions of Feynman are today shared by many others: when nanotechnology is seen as a general cross disciplinary technology, it has the potential to create a coming "industrial" revolution that will have a major impact on society and everyday life, comparable to or exceeding the impact of electricity and information technology.

=Nanocomponents, Tools, and Methods=

A positive spiral

As an emerging technology, the methods and components of nanotechnology are under continuous development and each generation is providing a better foundation for the following generation.

Seeing 'nano'

With regards to the methods, the Scanning tunneling microscope (STM) and  Atomic Force Microscope (AFM) were developed in the 1980s and opened up completely new ways to investigate nanoscale materials. An important aspect was the novel possibility to directly manipulate nanoscale objects. Transmission and scanning electron microscopes (TEM and SEM) had been available since the 30s, and offered the possibility to image as well as create nanodevices by electron beam lithography.

New nanomaterials

Several unique nanoscale structures were also discovered around 1990: the Carbon-60 molecule and later the  carbon nanotubes. In recent years, more complex nanostructures such as semiconductor nanowire heterostructures have also proven to be useful building blocks or components in nanodevices.

So what can I use this 'nano' for?

The applications of such nanocomponents span all aspects of technology: Electronics, optics/photonics, medical, and biochemical, as well as better and smarter materials. But to date few real products are available with nanoscale components, apart from traditional nanoscale products, such as paint with nanoparticles or catalytic particles for chemical reactors.

Prototype devices have been created from individual nanocomponents, but actual production is still on the verge. As when integrated electronics were developed, nanotechnology is currently in the phase where component production methods, characterization methods, tools for manipulation and integration are evolving by mutual support and convergence.

Difficult nanointegration

A main problem is reliable integration of the nanoscale components into microsystems, since the production methods are often not compatible. For fabrication of devices with integrated nanocomponents, the optimal manipulation technique is of course to have the individual components self-assembling or growing into the required complex systems. Self assembly of devices in liquids is an expanding field within nanotechnology but usually requires the components to be covered in various surfactants, which usually also influence the component properties. To avoid surface treatments, nanotubes and whiskers/wires can be grown on chips and microsystems directly from pre-patterned catalytic particles. Although promising for future large scale production of devices, few working devices have been made by the method to date.

The prevailing integration technique for nanowire/tube systems seems to be electron beam lithography (EBL) of metal structures onto substrates with randomly positioned nanowires deposited from liquid dispersions. By using flow alignment or electrical fields, the wire deposition from liquids can be controlled to some extent. The EBL method has allowed for systematic investigations of nanowires' and tubes' electrical properties, and creation of high performance electronic components such as field-effect transistors and chemical sensors. These proof-of-principle devices are some of the few but important demonstrations of devices nanotechnology might offer. In addition, nanomechanical structures have also recently been demonstrated, such as a rotational actuator with a carbon nanotube axis built by Fennimore et al.

A more active approach to creating nanowire structures is to use Scanning probe microscopy(SPM) to push, slide and roll the nanostructures across surfaces. SPM manipulation has been used to create and study nanotube junctions and properties. The ability to manipulate individual nanoscale objects has hence proven very useful for building proof-of-principle devices and prototypes, as well as for characterizing and testing components.

Top-down manufacturing takes bulky products and shrinks them to the nano scale, vs. bottom-up manufacturing is when individual molecules are placed in a specific order to make a product. The bottom-up self-assembly method may be important for future large scale production as well as many of the different approaches to improve the top-down lithographic processes. Such techniques could hence become important factors in the self-sustaining development of nanotechnology.

=Hot and hyped=

Suddenly everything is 'nano'

There's no question that the field of nanotechnology has quite a sense of hype to it - many universities have created new nanotech departments and courses. But there is also a vision behind the hype and emerging results - which are truly very few in industrial production, but nevertheless hold promise for a bright future. In the hype, many things that were once chemistry, microtechnology, optics, mesoscopic or cluster physics, have been reborn as nanotechnology.

Nanotech is old

You can find nanotechnology in the sunscreen you use in the summer, and some paints and coatings can also be called nanotech since they all contain nanoparticles with unique optical properties. In a way, nanoparticles have been known in optics for hundreds of years if you like to take a broad perspective on things, since they have been used to stain and color glasses, etc. since the middle ages. Nano-size particles of gold were used to create red pigments.

Catalysis is a major industrial process, without which not many of the materials we have around us today would be possible to make, and catalysis is often highly dependent on nanoscale catalytic particles. In this way thousands of tons of nanotechnology have been used with great benefit for years.

Nanoscale wires and tubes have only recently really been given attention with the advent of carbon nanotubes and semiconductor nanowires, while nanoscale films are ever present in antireflection coatings on your glasses and binoculars, and thin metal films have been used for sensitive detection with surface plasmons for decades. Surface plasmons are excitations of the charges at a surface. Nanowires actually were observed in the middle ages - well, they did not have the means to observe them, but saw whiskers grow from melted metals.

The better control over the nanostructure of materials has led to optimization of all these phenomena - and the emergence of many new methods and possibilities.

An example

Take for instance nano-optics: The surface plasmons turn out to be very efficient at enhancing local electrical fields and work as a local amplifier for optical fields, making a laser seem much more powerful to atoms in the vicinity of the surface plasmon. From this comes the surface enhanced raman spectroscopy which is increasingly used today because it makes it possible to do sensitive raman spectroscopy on the large majority of samples that would otherwise be impossible to make such spectra on. In addition, photonic crystals, fancy new quantum light sources that can make single photons on demand and other non-classical photon states are being developed, based on nanotechnology.

The future

There are definitely future scientific applications and commercial potential of all these new methods to handle light, use it for extremely sensitive detection and control its interaction with matter - and so it seems nanotechnology, being about making smaller versions of existing technology as well as new technology, is worth a bit of hype.

=References=

See also notes on editing this book Nanotechnology/About. .

title: Nanotechnology/Perspective


title: User:Klingoncowboy4/table


text:
Wikijunior talk:The Elements/Periodic Table

Linking Elements
Is it at all possible to link the images to the pages on that particular element? Klingoncowboy4 20:02, 4 October 2006 (UTC)
 * I see that this has been done, and that the table has been wikified. Klingoncowboy4 17:56, 2 November 2006 (UTC)

"WARNING: This page is 50 kilobytes long; some browsers may have problems editing pages approaching or longer than 32kb. Please consider breaking the page into smaller sections."
I propse that in order to deal with this we simnplify the history section. Klingoncowboy4 23:41, 21 November 2006 (UTC)

Missing Actinium!
The box for Actinium (number 89) is incorrect. It contains a duplicate of the Lanthanum (number 57) box. --Eliyahu 07:20, 28 November 2006 (UTC)

 * I have corrected the text box, but there is no Actinium.gif image for that square now. Could someone less graphically challenged than myself :) please upload one.  The symbols is Ac, the number is 89, and the atomic mass is 227.0277.  Thanks. --Eliyahu 07:51, 28 November 2006 (UTC)

Practical Application
A practical application stems from my firm's use of gas from a local landfill. Each month, we do a gas use inventory, and we correct earlier specific gravity assumption from an periodic gas composition analysis. The correction involves scaling via the molecular weights of the main components oxygen, nitrogen, methane, carbon dioxide and hydrogen. --Billymac00 18:45, 16 December 2006 (UTC)


text:
Nanotechnology/Nanophysics

Chemistry and Biochemistry are in many ways nanotechnologies working with nanoscale structures. In physics the classical laws of motion are not always valid on the nanoscale where a quantum mechanical model often is more suitable, and there are often a wealth of forces that are important that we do not consider very much in classical physics - the surface forces.

This part is about how nanosystems move, the forces that control the motion, and the ways we can model it.

=References=

See also notes on editing this book about how to add references Nanotechnology/About.

title: Nanotechnology/Nanophysics


text:
Nanotechnology/Metallic Nanostructures

=Metallic Nanostructures=

=Gold= The red color in some stained glasses has through centuries been made from gold nanoparticles, and its also gold particles that make the red color in many pregnancy tests. Gold nanoparticles are used on many technoogies: they have a red color because of a plasmon resonance and the noble metal makes them good for specific binding of molecules with thiol groups.

Copper
When copper is viewed on the nano level, several changes occur. the temperature of the metal decreases, as well as the fatigue limit decreases. Also, the tensile stress and elongation rate of the copper decreases.

this info is from: http://cat.inist.fr/?aModele=afficheN&cpsidt=14408198

=References=

See also notes on editing this book Nanotechnology/About.

title: Nanotechnology/Metallic Nanostructures


text:
Cookbook talk:Yorkshire Pudding

My late father, a Yorkshireman and inveterate eater of Yorkshire pudding (along with black pudding, and tripe and onions), once told me that his family used Yorkshire pudding as the basis for both a sweet and a savoury dish.

Made with meat juices (usually beef) it was a savoury; made without meat juices and spread usually with jam, it became a dessert.

Although we tended to create individual Yorkshire puddings as depicted in the illustration in the article, in fact the majority of Yorkshire pudding was apparently made in a single very large shallow baking tin. PeterBrooks 20:34, 4 October 2006 (UTC)

Three pints of milk in a Yorkshire pudding? Surely that can't be right -- I ended up with a bit vat of slop. --Sambeckwith 14:33, 2 December 2007 (UTC)
 * Depends on your "large spoons" (which given those measurements, I'd take as approx 4oz spoonfuls (which I have seen designed for flour) -- 80.4.120.91 (talk) 13:53, 19 February 2008 (UTC)

I was born and bred in Yorkshire.Yorkshire puddings should be cooked in dripping in a large roasting tin.The edges do puff up three to four inches while the middle is flatter. I always liked a bit of both. With mutton, sliced onions were added to the batter but with pork, chopped sage and onions were added. Roast pork without seasoned pudding was like bacon without an egg. The individual puddings don't taste like proper Yorkshire pudding should.Jam on Yorkshire pud. was quite popular but I didn't like it.

As a child we often had this on Sundays. Make the mix on Saturday night and leave in a cool place (fridge once we got one). Put the roast in the oven before all trooping off to church. On our return the house had a glorious smell of roast beef. :-) Turn on the veg.  When the beef was done remove it from the tray and leave to rest on the carving plate, pour off the excess juices and reserve for gravy.  Put the Yorshire mix into the roasting tin and return to the oven on maximum.  When the veg are done, make the gravy from the excess meat juices and the veg water.  When the Yorkshire is done serve with gravy as a first course.  Then for second course bring on the meat and veg.  How Mum always seemed to get the timing correct beats me! Martin of Sheffield (discuss • contribs) 16:28, 13 May 2019 (UTC)

title: Cookbook talk:Yorkshire Pudding


text:
User:PeterBrooks

INTRO
It's taken fifty three years for me to take a genuine interest in cooking. I guess that's as good a definition of "better late than never" as any :) PeterBrooks 20:36, 4 October 2006 (UTC)

title: User:PeterBrooks


text: Nanotechnology/Organic Nanomaterials

title: Nanotechnology/Organic Nanomaterials


text: Nanotechnology/Nano-bio Introduction

title: Nanotechnology/Nano-bio Introduction


text:
Cookbook:Conch

| Seafood | Shellfish

Conch are warm-water mollusks related to the snail.

Characteristics
The whole conch lives inside a large, pinkish spiked spiral shell. The meat is sweet in flavor and chewy before tenderizing, somewhat akin to crab or lobster.

Selection and storage
Conch meat is available either fresh in-shell, or shelled and frozen or canned. When selecting it, you want to look for white meat with no off or fishy smell. Because it is so perishable, fresh conch meat must be cooked immediately or frozen.

Preparation
If you're working with a fresh, whole conch, you'll need to break away the outermost layers of shell before using a tool to remove the meat. Afterwards, a sharp knife is used to remove the skin and leave just the meat. Once you have the meat, it's very common to tenderize it, either by pounding it or braising it until softened.

Use
Conch meat is eaten either raw, as in a salad, or cooked, as in fritters, jumbo, or chowder. It plays an important part in many Caribbean cuisines.

title: Cookbook:Conch


text:
Wikijunior:Languages/Romanian

What writing system(s) does this language use?
Romanian uses the Latin Alphabet, however it has 5 extra letters, which are: ă/Ă, â/Â, î/Î, ş/Ş and ţ/Ţ.

How many people speak this language?
24 million people speak Romanian as their first language. An additional 4 million people have learned it.

Where is this language spoken?
Romania is an official language in Romania, Moldova, and parts of Serbia. There are also many Romanian speakers in Western Europe and North America.

What is the history of this language?
People from Romania were called Dacians or Dacii. They spoke Dacian. Then the Romans invaded and they started speaking Latin. Most of the language today comes from Latin, but has words from Slavic languages.

Who are some famous authors or poets in this language?
Mihail Eminescu(Poet) Vasile Alecsandri(Poet) George Cosbuc(Poet) Ion Luca Caragiale(Play Writer) Mihail Sadoveanu(Writer) Ion Creanga(Writer)

What is a simple song/poem/story that I can learn in this language?
This is a Romanian birthday song

La mulţi ani cu sanatate Sã vã dea Domnul tot ce doriti, Zile senine şi fericire La mulţi ani sã traiti! (You reapeat this one more time.)

And then you go:

Cine sã traiascã? Cine sã traiascã? La mulţi ani! (The name of the person) sã traiascã (the name of the person) sã traiascã La mulţi ani! Cine sã traiascã? Cine sã traiascã? La mulţi ani!

(Example) Mihai sã traiascã! Mihai sã traiascã! La multi ani!

And then you scream out happy: LA MULŢI ANI!!!

title: Wikijunior:Languages/Romanian


text:
Nanotechnology/Environmental Impact

=Potential environmental impacts of nanotechnology= So far most of the focus has been on the potential health and environmental risks of nanoparticles and only a few studies has been made of the overall environmental impacts during the life cycle such as ecological footprint (EF) or life cycle analysis (LCA). The life cycle of nanoproducts may involve both risks to human health and environment as well as environmental impacts associated with the different stages.

The topics of understanding and assessing the environmental impacts and benefits of nanotechnology throughout the life cycle from extraction of raw materials to the final disposal have only been addressed in a couple of studies. The U.S. EPA, NCER have sponsored a few projects to investigate Life Cycle Assessment methodologies. Only one of these has yet published results on automotive catalysts and nanocomposites in automobiles , respectively, and one project was sponsored by the German government .

A 2007 special issue of Journal of Cleaner Production puts focus on sustainable development of nanotechnology and includes a recent LCA study in Switzerland .

The potential environmental impact of nanomaterials could be more far-reaching than the potential impact on personal health of free nanoparticles. Numerous international and national organizations have recommended that evaluations of nanomaterials be done in a life-cycle perspective , ,

This is also one conclusion from a recent series of workshops in the US on “green nanotechnology” (Schmidt, 2007) .

A workshop co-organised by US EPA/Woodrow Wilson Center and EU Commission DG Research put focus on the topic of Life Cycle Assessments of Nanotechnologies (Klöpffer et al., 2007) .

Heresome of the potential environmental impacts related to nanotechnological products in their life cycle are discussed followed by some recommendations to the further work on Life Cycle Assessment (LCA) of nanotechnological products.

However, when relating to existing experience in micro-manufacturing (which to a large extent resembles the top-down manufacturing of nanomaterials) several environmental issues emerge that should be addressed. There are indications that especially the manufacturing and the disposal stages may imply considerable environmental impacts. The toxicological risks to humans and the environment in all life cycle stages of a nanomaterials have been addressed above. Therefore, the potentially negative impacts on the environment that will be further explored in the following are:

 * Increased exploitation and loss of scarce resources;
 * Higher requirement to materials and chemicals;
 * Increased energy demand in production lines;
 * Increased waste production in top down production;
 * Rebound effects (horizontal technology);
 * Increased use of disposable systems;
 * Disassembly and recycling problems.

Exploitation and loss of scarce resources
Exploitation and loss of scarce resources is a concern since economic consideration is a primary obstacle to use precious or rare materials in everyday products. When products get smaller and the components that include the rare materials reach the nanoscale, economy is not the most urgent issue since it will not significantly affect the price of the product. Therefore, developers will be more prone to use materials that have the exact properties they are searching. For example in the search for suitable hydrogen storage medias Dillon et al. experimented with the use of fullerenes doped with Scandium to increase the reversible binding of Hydrogen. Other examples are the use of Gallium and other rare metals in electronics. While an increased usage of such materials may be foreseen due to the expected widespread use of nanotechnological products, the recycling will be more difficult (will be discussed more in detail later), resulting in non-recoverable dissemination of scarce resources.

Energy intensity of materials
An issue apart from the loss of resources is the fact that the extraction of most rare materials uses more energy and generates more waste than more abundant materials. Table 1 illustrates the energy intensity of a range of materials.

=Life cycle assessment (LCA)=

As mentioned there are not many studies on LCA of nanotechnology and much information has to be understood from extrapolation of experiences from MEMS and micro manufacturing.

In the micro world LCA has predominantly been used in the Micro-Electro-Mechanical Systems (MEMS) sector. The rapid development of technologies and limited availability of data makes full blown LCAs difficult and rather quickly outdated. An example is the manufacture of a PC for which the energy requirement in the late 1980’s were app. 2150 kWh whereas in the late 90’s efficiency were improved and only 535 kWh were necessary .

Using old data could result in erroneous results. Looking at the overall environmental impact this fourfold increase in efficiency has been overcompensated by an increase in number of sold computers from app. 21 mio to more than 150 mio causing an overall increase in environmental impact. This is often referred to as a rebound effect. For the development of cell phones, the same authors conclude that life cycle impacts vary significantly from one product generation to the next; hence generic product life cycle data should incorporate a “technology development factor” for main parameters.

A major trend is that shrinking product dimensions raise production environment requirements to prevent polluting the product. It involves energy intensive heating, ventilation and air conditioning systems. Clean room of class 10.000 for example requires app. 2280 kWh/m2∙a whereas a class 100 requires 8440 kWh/m2∙a. The same increase of requirements is relevant for supply materials like chemicals and gases. The demand for higher purity levels implies more technical effort for chemical purification, e.g. additional energy consumption and possibly more waste. Most purification technologies are highly energy intensive, e.g. all distillation processes, which are often used in wet chemical purification, account in total for about 7 % of energy consumption of the U.S. chemical industry . Chemicals used in large volumes in semiconductor industry are hydrofluoric acid (HF), hydrogen peroxide (H2O2) and ammonium hydroxide (NH4OH). These materials are used in final cleaning processes and require XLSI grades (0.1 ppb). Sulphuric acid is also used in large amounts, but it is a less critical chemical and mainly requires an SLSI level purity .

Micromanufacturing of other types of products also puts higher requirements on the quality and purity of the materials, e.g. a smaller grain size in metals because of the smaller dimensions of the final product. Additionally, a considerable amount of waste is produced. For example, up to 99% of the material used for microinjection moulding of a component may be waste since big runner are necessary for handling and assembly. However, recycling of this waste may not be possible due to requirements to and reduction of the material strength .

Miniaturisation also cause new problems in electronics recycling. Take-back will hardly be possible. If they are integrated into other product they need to be compatible with the recycling of these products (established recycling paths) .

The very small size and incorporation into many different types of products including product with limited longevity suggests an increased use of disposable systems is required.

Life cycle assessment of nanotechnology
As mentioned previously only few LCA studies have until now been performed for nanotechnological products. A two day workshop on LCA of nanotechnological products concluded that the current ISO-standard on LCA (14040) applies to nanotechnological products but also that some development is necessary

The main issues are that:sometimes it cracks the nerve
 * There is no generic LCA of nanomaterials, just as there is no generic LCA of chemicals.
 * The ISO-framework for LCA (ISO 14040:2006) is fully suitable to nanomaterials and nanoproducts, even if data regarding the elementary flows and impacts might be uncertain and scarce. Since environmental impacts of nanoproducts can occur in any life cycle stage, all stages of the life cycle of nanoproducts should be assessed in an LCA study.
 * While the ISO 14040 framework is appropriate, a number of operational issues need to be addressed in more detail in the case of nanomaterials and nanoproducts. The main problem with LCA of nanomaterials and nanoproducts is the lack of data and understanding in certain areas.
 * While LCA brings major benefits and useful information, there are certain limits to its application and use, in particular with respect to the assessment of toxicity impacts and of large-scale impacts.
 * Within future research, major efforts are needed to fully assess potential risks and environmental impacts of nanoproducts and materials (not just those related to LCA). There is a need for protocols and practical methodologies for toxicology studies, fate and transport studies and scaling approaches.
 * International cooperation between Europe and the United States, together with other partners, is needed in order to address these concerns.
 * Further research is needed to gather missing relevant data and to develop user-friendly eco-design screening tools, especially ones suitable for use by small and medium sized enterprises.

Some of the concerns regarding the assessment of toxicological impacts is closely linked to the risk assessment of nanoparticles and have to await knowledge building in this area. However, the most striking is the need for knowledge and cases where LCA are applied in order to increase understanding of nanotechnological systems – what are the potential environmental impacts? How do they differ between different types of nanotechnologies? Where should focus be put in order to prevent environmental impacts? Etc.

Additional resources

 * Nanometer societal assessment of nanotechnological applications prior to market release.

=Contributors to this page= This material is based on notes by
 * Stig Irving Olsen, Department of Manufacturing Engineering and Management, Building 424, NanoDTU Environment, Technical University of Denmark

and also by

 * Steffen Foss Hansen, Rikke Friis Rasmussen, Sara Nørgaard Sørensen, Anders Baun. Institute of Environment & Resources, Building 113, NanoDTU Environment, Technical University of Denmark
 * Kristian Mølhave, Dept. of Micro and Nanotechnology - DTU - www.mic.dtu.dk

=References=

See also notes on editing this book Nanotechnology/About.

title: Nanotechnology/Environmental Impact