Nick Draper
email: nick.draper@canterbury.ac.nz

David Giles

Nicola Taylor

Laurent Vigouroux

Vanesa Españ A-Romero

Jiří Baláš

Ignacio Solar Altamirano

Franziska Mally

Ina Beeretz

Jorge Couceiro Canalejo

Vanesa Espan ˜ A-Romero

Gabriel Josseron

Jan Kodejška

María José

Arias Téllez

German Gallo

Cabeza De Vaca

Espan ˜a-

Couceiro Canalejo

Performance Assessment for Rock Climbers: The International Rock Climbing Research Association Sport-Specific Test Battery

Keywords: endurance, flexibility, power, strength, successful rock climbing

établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

performance. In regard to the physiological aspects, 4 parameters have been regularly cited by coaches and researchers as key components of climbing that underpin performance. [START_REF] Draper | Sport-specific power assessment for rock climbing[END_REF] These physiological components are strength, power, flexibility, and endurance. [START_REF] Draper | Sport-specific power assessment for rock climbing[END_REF][START_REF] Draper | Adventure Sport Physiology[END_REF][START_REF] Macleod | Physiological determinants of climbing-specific finger endurance and sport rock climbing performance[END_REF][START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF] Given the importance of these factors for climbing, it is important to identify valid and reliable sport-specific tests that assess each of these parameters for use by researchers and coaches working with climbers.

The International Rock Climbing Research Association (IRCRA) was formed in 2011 to create a nexus for collaboration not only between countries and institutions but also between researchers, climbers, and coaches. In addition, through its biennial Congress and website forums, the IRCRA aims to bring greater consistency to research reporting. Examples of the IRCRA's work can be found in the publication of their position statement in regard to climbing grades. [START_REF] Draper | Comparative grading scales, statistical analyses, climber descriptors and ability grouping: International Rock Climbing Research Association position statement[END_REF] In this document, the IRCRA established a recommended format for study reporting to facilitate comparison between studies, clearer ability descriptors, and a numerical scale to bring greater consistency to statistical analyses. [START_REF] Draper | Comparative grading scales, statistical analyses, climber descriptors and ability grouping: International Rock Climbing Research Association position statement[END_REF] At the 2014 IRCRA Congress, held in Pontresina, Switzerland, the need for sport-specific assessment tools was highlighted by researchers and coaches. As a result of these discussions, a working group was established to develop a sport-specific battery of tests for coaches, climbers, and researchers. A key aspect of this development work was to ensure that the tests were valid, and reliable measures were taken so that they could be used as measurement tools for future intervention and cohort studies. The resultant multicenter trial established a collaboration between researchers and coaches from 7 countries across the globe with the purpose being to identify and assess the validity and reliability of a sport-specific test battery for rock climbing.

Methods

This study involved 2 phases, with phase 1 being the development of the test battery and assessment for face and content validity. In phase 2, the developed tests were assessed for construct validity and testretest reliability. While not a health study per se, the Consensusbased Standards for the Selection of Health Measurement Instruments was used to guide the development of the study and to evaluate the quality of each of the tests in the battery. [START_REF] Mokkink | The COSMIN checklist for assessing the methodological quality of studies on measurement properties of health status measurement instruments: an international Delphi study[END_REF] After design and review using the Consensus-based Standards for the Selection of Health Measurement Instruments checklist, the study achieved good to excellent Consensus-based Standards for the Selection of Health Measurement Instruments rating prior to commencement. The study was approved by the University of Derby institutional research ethics committee (LSREC_1516_01). Informed consent from all participants was received before participation.

Phase 1

Following the IRCRA Congress in Pontresina, a working group comprising of academics, coaches/practitioners, and climbers (n = 20) was formed to develop the battery of tests using the Delphi method. [START_REF] Okoli | The Delphi method as a research tool: an example, design considerations and applications[END_REF] Details of the working group can be found in the IRCRA Test Manual (see Supplementary Material [available online]). [START_REF] Giles | The IRCRA performance-related test battery for climbers 2015[END_REF] The working group endorsed the physiological parameters of strength, power, flexibility, and endurance, as previously identified in the research, but in addition included a fifth element of core stability, due to its importance with regard to quality movement in climbing. The battery of tests for the study underwent several stages in development, beginning with a desktop study. The desktop study identified the published sport-specific tests that had undergone validity and reliability assessment. This led to the inclusion of the flexibility assessment, 8 maximal finger strength, [START_REF] Baláš | Sport-specific finger flexor strength assessment using electronic scales in sport climbers[END_REF] and powerslap tests [START_REF] Draper | Sport-specific power assessment for rock climbing[END_REF] in the final test battery, as tests 1, 2, 3, and 5, respectively. Following this, in an iterative process, the working group further developed the climbing-specific foot raise [START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF] to create tests 1 and 2 and then went on to develop, pilot test, revise, and agree on a further 6 tests for inclusion in the final test battery, ensuring that each of the agreed physiological components, including core stability, were assessed.

Each of the tests was examined for face and content validity prior to inclusion in the test battery through a process involving internationally recognized experts (n = 3) who met in person to revise and further develop each test to ensure the content validity of each test after face validity had been agreed by members of the working group (n = 6). The review process included the development of specific test apparatuses, in situ observations of climber performance on each of the tests, and a subjective assessment of the sport-specificity of each test. Full details of the tests including test apparatus specifications and protocols can be found in the test manual (see Supplementary Material [available online]). [START_REF] Giles | The IRCRA performance-related test battery for climbers 2015[END_REF] The final test battery, along with its associated physiological parameter(s), can also be found in IRCRA Test Manual (see Supplementary Material [available online]). [START_REF] Giles | The IRCRA performance-related test battery for climbers 2015[END_REF] Phase 2

Participants

As a multicenter trial, this study represents one of the largest completed with rock climbers, with 132 participants (mean [SD]) age 27.3 (7) years, body mass 65 (11) kg, height 170.5 (9) cm, body mass index 22.4 (2.5) kg/m 2 , body fat 17.7% (8%), who had 6.6 (6) years climbing experience and were, at the time of the study, training 2.5 (1) sessions per week. The participants consisted of 45 female and 87 male climbers, of whom 12 were tested in Austria, 21 in Chile, 15 in both the Czech Republic and France, 33 in Spain, and 36 in the United Kingdom. In Spain, the data were collected at 2 centers, one in Cadiz, the other in Madrid (Spain 1 and Spain 2, respectively). In 2011, the IRCRA published a classification system for climbers to provide a suggested ability-based nomenclature for reporting of climbing grades. [START_REF] Draper | Comparative grading scales, statistical analyses, climber descriptors and ability grouping: International Rock Climbing Research Association position statement[END_REF] This classification system being based on the validity of self-reported grades as had been previously demonstrated. [START_REF] Draper | Reporting climbing grades and grouping categories for rock climbing[END_REF] The climbers, who completed a health history and informed consent prior to commencing their participation, self-reported as being of lower grade (20), intermediate (30), advanced (63), and elite (19) level. Specific characteristics of the group can be found in Table 1. The climber experience and health history questionnaires can be found on pages 22 and 33 of the Test Manual (see Supplementary Material [available online]), [START_REF] Giles | The IRCRA performance-related test battery for climbers 2015[END_REF] respectively.

Procedure

To assess the construct validity and reliability of each of the tests, a protocol for testing was established as shown in the IRCRA Test Manual (see Supplementary Material [available online]). [START_REF] Giles | The IRCRA performance-related test battery for climbers 2015[END_REF] To ensure each climber arrived at the laboratory in a similar physical condition, a minimum of 7 days was required between visits, and the participants were asked to rest completely in the 24 hours prior to each test. For each of the 3 laboratory visits, a 5-minute rest was allowed between tests. On each visit to the laboratory, the participants completed a standardized warm-up, which is described in detail in the test manual. The warm-up briefly consisted of 5 minutes of walking and jogging, 5 minutes of general mobilizing, and 5 minutes of specific exercises, such as pull-ups, leg raises, and reduced weight finger hangs, which mimicked the movement required in the tests. The warm-up was developed from methods used in previous research. [START_REF] Binney | Aerobic and anaerobic power: power endurance[END_REF][START_REF] Gresham | Training and technique for climbers of all levels[END_REF][START_REF] Tenke | Warm-Up and Preparation for Athletes of All Sports[END_REF] Anthropometric measurements were made as described in the test manual, and it included height, mass, arm span, forearm volume, body density, and skinfold thicknesses. [START_REF] Durnin | Body fat assessed from total body density and its estimation from skinfold thickness: measurements on 481 men and women aged from 16 to 72 years[END_REF][START_REF] Heyward | Advanced Fitness Assessment and Exercise Prescription[END_REF][START_REF] Siri | Techniques for measuring body composition[END_REF] Version 1.6 of the test manual [START_REF] Giles | The IRCRA performance-related test battery for climbers 2015[END_REF] was followed at each of the test centers, along with e-mail and telephone clarifications, to ensure consistency of the method. In addition, videos were watched at each test center to ensure that the method for each test was the same across the study. Each test center built the test apparatuses to the specifications supplied in the test manual. For the leg raise tests (T1 and T2), both left and right legs were tested for all participants. In T1, rotation at the shoulders was allowed, while for T2, no rotation at the shoulders was allowed, so the shoulders had to remain parallel to the test board during text execution. For the finger strength test (T3), both open and crimped holds were tested. For a description of different holds common to rock climbing, see Peters. [START_REF] Peters | Rock Climbing Essential Skills and Techniques[END_REF] For powerslap test (T5) and the bent-arm hang (T7), left and right arms were tested.

Construct validity for each of the tests was examined by ability level. (Higher grade climbers expected to have higher scores than lower grade climbers.) As can be seen in the IRCRA Test Manual (see Supplementary Material [available online]), for all tests with the exception of tests 3 and 5 (as described previously) and the 2 core stability tests (T9 and T10), were repeated to assess test-retest reliability between and across centers. At each of the centers, the researchers followed the protocol as described in the test manual to administer each of the tests. 11

Statistical Analysis

Distributions, descriptive statistics, analyses of variance, correlations, and regressions were calculated using SPSS (version 25.0; IBM SPSS Statistics Inc, Chicago, IL), while Bland-Altman plots [START_REF] Altman | Measurement in medicine: the analysis of method comparison studies[END_REF][START_REF] Bland | Statistical methods for assessing agreement between two methods of clinical measurement[END_REF] were calculated using Microsoft Excel (version 2016 MSO 16.0.4738.1000; Microsoft Redmond, Washington, WA). Data were assessed for violations of the assumptions of normality of distribution using the Shapiro-Wilk test with results showing Gaussian distribution. A 1-way analysis of variance with least-significantdifference post hoc comparisons as necessary was used to explore the effects of ability level on scores for each of the 10 tests. To ascertain the reliability of the tests, a series of Bland-Altman plots were completed, and coefficients of variation were calculated to examine the levels of agreement. Cronbach alpha and intraclass correlations were calculated to assess test-retest reliability. Data are reported as mean (SD), and P ≤ .05 was set for accepting statistical significance.

Results

The means and SD for each of the tests are shown in Figure 1. As can be seen from this figure, the tests that appeared through visual inspection to differentiate climbers by ability category were the finger strength (T3-open and crimped, left and right), the finger hang (T4), the powerslap (T5), the bent-arm hang (T6), 1-arm bentarm hang (T7-left and right), and pull-ups test (T8). Tests 1 and 2 (leg raise tests-flexibility) and tests 9 and 10 (plank and leg raise, respectively-core stability) did not appear to differentiate between climbers of differing abilities. The results of the analysis of variance tests (see Table 2) indicated that there were significant differences between groups for all tests with the exception of test 1 (right) and test 2 (left and right).

Visual inspection of the data in Table 2 suggests that in principle scores on tests improved with climbing ability; that is, high-grade climbers appeared to score higher on tests than their lower-ability counterparts. With regard to assessing construct validity, tests 4 and 6 performed well in differentiating between all grades of climbers. Test 5, when left and right powerslap were considered together, showed increased scores by ability. Test 8 showed good construct validity apart from differentiation between intermediate and advanced level climbers. Test 7 (single-arm bent-arm hang), which was similar to test 6 in showing significant differences by group, lacked differentiation for lower grade, intermediate, and advanced climbers. In these groups, there were several climbers who could not hold the 1-arm position at all, whereas they could with the 2-arm version (test 6). Tests 1, 2, 3, 9, and 10 performed poorly with respect to differentiation and could not be said to hold construct validity for climbing. About reliability, only tests 4, 6, and 8 were assessed for testretest reliability, as these were the tests which displayed strong construct validity. Test 5, the powerslap test, performed well in regard to construct validity and had already been assessed for testretest reliability in a previous study, so this was not replicated in our test protocol (5). The results of Cronbach alpha and intraclass correlations tests can be seen in Table 3. As can be seen from Table 3, all 3 tests displayed strong test-retest reliability as a whole (across countries) and also within each country. The only exception being French data for the finger hang and 2-arm bent-arm hang which had a moderate result (0.771 and 0.624; 0.657 and 0.480, respectively).

The Bland-Altman plots for each of the 3 tests can be seen in Figure 2. As can be seen in this figure, there were good levels of agreement between tests. Table 4 provides the coefficient of variation for tests 4, 5, 6, and 8. Taken across all grades, the tests demonstrated very good to acceptable levels of variation. On tests 4 and 8 for lower grade females, the variation >30% is not acceptable. Tests 4, 5, 6, and 8 demonstrated strong construct validity, showed good levels of agreement, and displayed strong test-retest reliability. Table 5 provides details of regression modeling for tests 4, 5, 6, and 8. As can be seen from this modeling, the variance explained across all models was higher for females (R 2 = .52-.58) than for males (R 2 = .31-.36). For both males and females, the variance explained increased only marginally when moving from model 2 to 3 and including the 2-arm bent-arm hang (T6) and pull-ups (8).

Discussion

Research across many sports has highlighted the benefits of valid and reliable, sport-specific tests for monitoring performance in athletes. [START_REF] Uljevic | Reliability, validity, and applicability of isolated and combined sport-specific tests of conditioning capacities in top-level junior water polo athletes[END_REF][START_REF] Rodríguez-Rosell | Traditional vs. sport-specific vertical jump tests: reliability, validity, and relationship with the legs strength and sprint performance in adult and teen soccer and basketball players[END_REF][START_REF] Spasic | Reactive agility performance in handball; development and evaluation of a sportspecific measurement protocol[END_REF] Although a generally more recent area of research focus, the need for sport-specific measurement tools for rock climbing has been recognized by coaches and researchers alike, and there are an increasing number of studies examining novel tests for the sport. [START_REF] Abreu | TEST-retest reliability of kinetic variables measured on campus board in sport climbers[END_REF][START_REF] Draper | Sport-specific power assessment for rock climbing[END_REF][START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF][START_REF] Baláš | Sport-specific finger flexor strength assessment using electronic scales in sport climbers[END_REF][START_REF] Michailov | A sportspecific upper-body ergometer test for evaluating submaximal and maximal parameters in elite rock climbers[END_REF][START_REF] Brent | Development of a performance assessment tool for rock climbers[END_REF] These studies have, however, been limited in regard to the total number and ability levels of the participants. The mission of the IRCRA is to foster collaboration not only between researchers, coaches, and climbers but also between countries to increase our knowledge and understanding of the sport. This is increasingly important from a performance perspective since the inclusion of rock climbing in the Olympic schedule for the Tokyo 2021 Olympic Games. The collaboration brought about through the IRCRA enabled the establishment of the largest rock climbing study to date with data collected from centers in 7 countries where climbing is a popular performance and recreational activity. The aim of the resultant study was to examine the validity, reliability, and performance assessment potential of 10 sport-specific performance measures for rock climbing.

Researchers identified flexibility, power, strength, and endurance as the key performance parameters for rock climbing, with the recognition that core stability plays an additional key role in successful performance. [START_REF] Draper | Sport-specific power assessment for rock climbing[END_REF][START_REF] Draper | Adventure Sport Physiology[END_REF][START_REF] Macleod | Physiological determinants of climbing-specific finger endurance and sport rock climbing performance[END_REF][START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF][START_REF] Baláš | Sport-specific finger flexor strength assessment using electronic scales in sport climbers[END_REF][START_REF] Michailov | A sportspecific upper-body ergometer test for evaluating submaximal and maximal parameters in elite rock climbers[END_REF] Through the Delphi method, an expert panel identified, developed, and refined the protocol for 10 sport-specific rock climbing tests to be included in the study. The key finding of the study was that tests 4, 5, 6, and 8, namely the finger hang, powerslap, 2-arm bent-arm hang, and the pull-ups tests respectively, demonstrated high levels of validity and reliability as sport-specific measures. As shown in Table 1, these tests were designed to assess climbing-specific endurance and power. The remaining tests, tests 1, 2, 3, 7, 9, and 10, which assessed climbingspecific flexibility, strength, endurance, and core stability did not perform as well in regard to validity for rock climbing and in their current forms could not be considered as sport-specific measures across all ability levels. Flexibility, the component designed to be assessed in tests 1 and 2, had been studied in a wider series of flexibility tests by Draper et al. [START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF] In this 2-phase pilot study, with 46 and then 21 participants, 6 flexibility measures were assessed for validity and reliability. This study found significant differences between elite climbers and lower grade (novice) and intermediate climbers but not advanced climbers. [START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF] Our research could not support this finding with only the left foot raise in test 1 identifying a significant but limited difference between the groups (Table 3). Taken together, our study and the previous one perhaps suggest that flexibility is important for climbing, but there may be a threshold above which this fitness component becomes a lesser determinant of performance. Examining the data from the 2 studies, it is a threshold that perhaps differentiates advanced and elite climbers from intermediate and lower grade climbers. Once this threshold is reached, flexibility is not a critical component that differentiates performance at advanced and elite levels. Further research in this area might examine the potential of a new combination of tests, such as the lateral foot raise test and footloading flexibility test, [START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF] to examine whether there is a further differential improvement in flexibility above the intermediate level.

In future work with athletes at lower grade and intermediate levels, it may be beneficial to assess flexibility to examine if it is a rate limiter for performance improvement. However, for higher grade climbers perhaps only after returning to climbing after injury would assessment of flexibility merit inclusion in a battery of tests for climbers of advanced and elite level.

Strength, particularly grip strength, has been highlighted by coaches and researchers as a key component of fitness for climbers. [START_REF] Macleod | Physiological determinants of climbing-specific finger endurance and sport rock climbing performance[END_REF][START_REF] Baláš | Sport-specific finger flexor strength assessment using electronic scales in sport climbers[END_REF][START_REF] Gresham | Training and technique for climbers of all levels[END_REF] Our results lend support to the importance of strength for rock climbers with significant differences in strength across groups for finger open and crimp with both right and left hand. The results, however, indicate significant differences between advanced and elite climbers in comparison to lower grade climbers and elite climbers with intermediate climbers, but the tests do not differ across all categories of climbers. This data suggest that there is a threshold that distinguishes elite and advanced climbers from lower ability climbers, but not across all grades of climbers.

Test 7, the 1-arm bent-arm hang (right and left arm), also assessed endurance in a similar manner to test 6 (the 2-arm version); however, results showed that this test had limitations regarding lower grade, intermediate and advanced climbers, many of whom scored zero for this test. While the group means, as shown in Figure 2, reveal increases in the mean score by ability group, the results also revealed that all the lower grade climbers, and many of the intermediate and even advanced level climbers, scored zero for the test, meaning that they were not able to hold this position at all. For the 2-arm version, test 6, all climbers were able to score on the test, and it did provide good differentiation between ability groups. As a result of this finding, test 7 could only be recommended as a performance measure for elite climbers; however, test 6 provides a valid and reliable measure for all climbers.

Core stability was identified by our expert panel as an important component for climbing performance. As a consequence, tests 9 and 10 were designed, in an exploratory manner, as potential measures of core stability that might distinguish climbers of differing abilities. Results of testing revealed a similar pattern for both tests, with performance improving up to the advanced level, but with mean scores for elite climbers not as high as those for advanced climbers. Furthermore, intermediate, advanced, and elite climbers performed significantly (P < .05) better on both tests than lower grade climbers. Both tests were conducted to volitional failure, and it is possible that while advanced climbers displayed greater core stability than lower grade and intermediate climbers, the elite climbers reached their volitional limit earlier due to psychological aspects, which provides a limitation to both tests. This finding is in keeping with work by Leetun et al, [START_REF] Leetun | Core stability measures as risk factors for lower extremity injury in athletes[END_REF] along with Weir et al, [START_REF] Weir | Core stability: inter-and intraobserver reliability of 6 clinical tests[END_REF] who found that while core stability is likely an important performance parameter that is difficult to measure reliably and may be highly sportspecific. Further research on sport-specific measures would be required for climbing, prior to their inclusion in a battery of tests

Practical Application

Valid and reliable sport-specific measures of physiological functioning are vital in the preparation of athletes for competition. The results of our research for the new Olympic sport of rock climbing verify the suitability of the finger hang and powerslap tests as valid and reliable sport-specific performance measures for use by researchers, coaches, and climbers. Coaches could use these tests to assess physiological adaptation brought about through prescribed training programs implemented for climbers from lower grade to the elite levels.

Conclusion

The results of our study suggest that if only one test was possible in a research context, the finger hang, test 4, is a reliable measure that can distinguish across all ability levels. If a more complete picture of climbing performance is required, then researchers might consider including tests 4 and 5 (finger hang and powerslap) with scores on these 2 tests able to account for 35% to 56% of the variance between climbers for males and females, respectively.

Figure 1 -

 1 Figure 1 -Raw score means and SD for each of the tests, left and right hand shown as appropriate. Note. Results for test 1 are for leg raise with rotation and for test 2 are leg raise without rotation.

Figure 2 -

 2 Figure 2 -Bland-Altman plots for finger hang (test 4), 2-arm bent-arm hang (test 6), and pull-ups (test 8).

Table 1

 1 Number of Participants in Each Ability Category and Mean (SD) Characteristics for the Climbers in the Study

		All	Lower grade	Intermediate	Advanced	Elite
	N
	Male	87	13	19	44	11
	Female	45	7	11	19	8
	Age, y
	Male	27.3 (8)	23.84 (7)	31.15 (7)	27.54 (8)	27.59 (7)
	Female	27.2 (8)	24.6 (8)	29.21 (8)	28.4 (6)	26.18 (11)
	Body mass, kg
	Male	69.8 (14)	80.68 (15)	68.81 (8)	67.58 (8)	71.45 (5)
	Female	57.3 (13)	67.25 (13)	58.32 (7)	56.56 (10)	49.24 (5)
	Height, cm
	Male	174.6 (27)	177.51 (6)	174.93 (8)	172.99 (7)	176.75 (2)
	Female	162.3 (25)	164.05 (6)	166.16 (8)	161.92 (9)	158.76 (6)
	Arm span, cm
	Male	180.3 (33)	180.99 (4)	179.1 (9)	179.61 (9)	185.49 (2)
	Female	163.8 (35)	165.75 (7)	167.63 (8)	162.38 (8)	163.99 (6)
	Body mass index, kg/m 2
	Male	22.8 (4)	25.59 (4)	22.45 (2)	22.56 (2)	22.88 (2)
	Female	21.7 (4)	24.91 (4)	21.12 (2)	21.45 (2)	19.5 (1)
	Body fat, %
	Male	13.7 (6)	18.38 (5)	13.15 (6)	13.63 (5)	11.86 (2)
	Female	24 (7)	28.46 (7)	24.79 (5)	24.35 (7)	18.81 (4)
	Years climbing
	Male	7.4 (6)	3.52 (6)	6.95 (6)	8.22 (6)	13 (7)
	Female	5.2 (4)	2.65 (2)	3.77 (3)	5.71 (5)	7.82 (3)
	Sessions per week
	Male	2.7 (1)	1.05 (0.7)	2.79 (1)	2.92 (1.3)	3.56 (1)
	Female	2.5 (1)	0.81 (0.4)	1.75 (0.6)	2.71 (1.1)	4 (1)

Table 2

 2 Results of ANOVA Tests for the International Rock Climbing Research

	Association Test Battery
				ANOVA
	Test		F	P	η 2	1-2 1-3 1-4 2-3 2-4 3-4
	Test 1: Left leg raise
	Combined		4.218	.007	.101	*	*	*
	Male		7.167	<.0005 .228	*	*	*	*
	Female		0.299	.826	.024
	Test 1: Right leg raise
	Combined		2.588	.057	.064
	Male		5.167	.003	.175	*	*	*	*
	Female		0.251	.860	.02
	Test 2: Left leg raise
	Combined		0.994	.399	.026
	Male		3.032	.035	.111	*	*	*
	Female		0.611	.612	.048
	Test 2: Right leg raise
	Combined		0.642	.589	.017
	Male		1.711	.172	.066
	Female		0.425	.736	.034
	Test 3: Left open finger	strength
	Combined		4.42	.006	.127		*	*	*
	Male		8.788	<.0005 .305		*	*	*	*	*
	Female		4.021	.017	.309	*	*	*
	Test 3: Right open finger	strength
	Combined		3.707	.014	.106		*	*	*
	Male		5.901	.001	.219		*	*	*	*
	Female		2.551	.077	.221		*	*
	Test 3: Left crimp finger	strength
	Combined		3.997	.010	.113		*	*
	Male		4.811	.004	.186		*	*	*
	Female		3.528	.028	.282		*	*	*
	Test 3: Right crimp finger	strength
	Combined		3.145	.029	.094		*	*
	Male		4.413	.007	.181		*	*	*	*
	Female		6.132	.003	.405
	Test 4: Continuous finger	hang
	Combined		24.235 <.0005 .394	*	*	*	*	*	*
	Male		12.430 <.0005 .341	*	*	*	*	*
	Female		16.618 <.0005 .581		*	*	*	*	*
	Test 5: Left powerslap
	Combined		6.758	<.0005 .151		*	*	*	*
	Male		9.220	<.0005 .275	*	*	*	*	*
	Female		12.746 <.0005 .508		*	*	*	*	*
	Test 5: Right powerslap
	Combined		4.347	.006	.103	*	*	*
	Male		5.171	.003	.175	*	*	*
	Female		7.891	<.0005 .390	*	*	*	*	*
	Test 6: 2-arm bent-arm hang
	Combined		15.259 <.0005 .287	*	*	*	*	*
	Male		13.122 <.0005 .350	*	*	*	*	*
	Female		8.432	<.0005 .406	*	*	*	*
									(continued)

p p

Table 2

 2

	(continued)
			ANOVA
	Test	F	P	η 2	1-2 1-3 1-4 2-3 2-4 3-4
	Test 7: Left bent-arm hang
	Combined	4.478	.005	.105		*	*	*	*
	Male	4.756	.004	.163		*	*	*	*
	Female	3.764	.019	.234			*	*	*
	Test 7: Right bent-arm hang
	Combined	4.856	.003	.113		*	*	*	*
	Male	5.689	.001	.189		*	*	*	*
	Female	1.863	.153	.131
	Test 8: Pull-ups
	Combined	5.464	.002	.113	*	*	*	*	*
	Male	8.088	<.0005 .260	*	*	*	*	*
	Female	8.397	<.0005 .426		*	*	*	*
	Test 9: Plank
	Combined	7.385	<.0005 .163	*	*	*
	Male	3.697	.015	.132	*	*
	Female	6.311	.001	.338	*	*	*
	Test 10: Leg raise
	Combined	5.723	.001	.113	*	*	*
	Male	2.329	.082	.088
	Female	4.890	.006	.290		*	*	*

Abbreviation: ANOVA, analysis of variance. *Significant post hoc difference between these groups (P < .05), also indicated by bold P values.

Table 4

 4 Coefficients of Variation for Each of the Selected Tests

	Test	All, %	Lower grade, %	Intermediate, %	Advanced, %	Elite, %
	Test 4: Finger hang
	All	18	32	22	12	13
	Male	16	25	18	12	10
	Female	24	53	29	11	16
	Test 5: Powerslap
	All	7	14	11	4	3
	Male	4	6	5	3	3
	Female	13	34	23	6	2
	Test 6: 2-arm bent hang
	All	15	24	17	11	18
	Male	13	13	18	11	9
	Female	19	56	15	11	27
	Test 8: Pull-ups
	All	14	19	18	13	5
	Male	10	10	11	9	6
	Female	24	47	31	20	5

Table 5

 5 Results of Regression Modeling Using Tests 4, 5, 6, and 8 (Finger Hang, Powerslap, 2-Arm Bent-Arm Hang, and Pull-Ups, Respectively), With the Dependent Variable of Climbing Ability elite climbers. These tests might prove beneficial with lower grade and intermediate climbers in the context of studies designed to improve climber performance.

		Dependent variable: Climbing ability
	B	SE B	β	P

*P < .05.

for

  Given the physiological overlap between tests 4, 6, and 8 and the lack of further explained variance through regression modeling when tests 6 and 8 (2-arm bent-arm hang and pull-ups) are added to the test battery, it can only be recommended to include the finger hang and powerslap in a test battery when using climbers of different ability levels. The results of that future research is required to identify tests of flexibility, strength, and core stability that are specific to climbing and can differentiate between ability groups. Future studies should also examine the effect of age on scoring in these tests, in work similar to Malina et al[START_REF] Malina | Maturity-associated variation in sport-specific skills of youth soccer players aged 13-15 years[END_REF] for soccer.

	our study indicate
	Finger hang	0.109	0.013	0.621	.001*
	odel 2: R 2 = .46; ΔR 2 = .45; P < .001*
	Finger hang	0.082	0.015	0.465	.001*
	Powerslap	0.060	0.016	0.314	.001*
	Finger hang	0.095	0.015	0.723	.001*
	odel 2: R 2 = .56; ΔR 2 = .53; P < .001*
	Finger hang	0.077	0.019	0.582	.001*
	Powerslap	0.044	0.028	0.230	.122


Nick Draper

David Giles

Volker Schöffl

Franz Konstantin Fuss

Phillip Watts

Peter Wolf

Jiří Baláš

JIR ˇ I ´ BALA ´ S ˇ8 Vanesa Espana-Romero

Gina Blunt Gonzalez

Simon Fryer

Volker Scho

¨ Ffl

Maurizio Fanchini

Laurent Vigouroux

Ludovic Seifert

Lars Donath

Manuel Spoerri

Kelios Bonetti

Kevin Phillips

Urs Sto ¨ Cker

Felix Bourassa-Moreau

Inmaculada Garrido

Scott Drum

Stuart Beekmeyer

Jean-Luc Ziltener

Nicola Taylor

Ina Beeretz

Franziska Mally

ARIF Mithat Amca

Caroline Linhart

Edgardo Abreu

Comparative grading scales, statistical analyses, climber descriptors and ability grouping: International Rock Climbing Research Association position statement

Keywords: rock climbing, ability grouping, climbing grade, comparative table, statistics

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The International Rock Climbing Research Association (IRCRA) was formed in 2011 as a forum through which climbers, coaches and researchers, working in the area of rock climbing, could come together to share experience, collaborate over research and to provide a platform for knowledge exchange. To date the Association has held two congresses, the first in 2011 in Christchurch, New Zealand, and the second in Pontresina, Switzerland in 2014. The next congress will be held in the USA in 2016. Membership of the Association is free and includes climbers, coaches, climbing wall designers and researchers from around the world; the website for the IRCRA can be found at www.ircra.rocks.

Rock climbing is an increasingly popular recreational and competitive sport, with a growing research base [START_REF] Bala ´s | Performance evaluation of the machine learning algorithms used in inference mechanism of a medical decision support system[END_REF]Draper et al., 2011a;[START_REF] Espan ˜a Romero | Body fat measurement in elite sport climbers: Comparison of skinfold thickness equations with dual energy X-ray absorptiometry[END_REF][START_REF] Watts | Physiology of difficult rock climbing[END_REF]. As the sport has developed, the number of disciplines has increased and now includes such diverse activities as mountaineering, big wall climbing, bouldering, deep water soloing, sport climbing, traditional climbing, ice climbing and mixed climbing [START_REF] Macleod | Physiological determinants of climbing-specific finger endurance and sport rock climbing performance[END_REF]. As the research base has grown, ~550 papers have been published on the sport, there has been an increasing diversity in the nomenclature to describe ability groups, the grading systems and climber characteristics reported, as well as a wide variety of grade conversion methods employed to enable statistical analysis of results [START_REF] Espan ˜a Romero | Body fat measurement in elite sport climbers: Comparison of skinfold thickness equations with dual energy X-ray absorptiometry[END_REF][START_REF] Macleod | Physiological determinants of climbing-specific finger endurance and sport rock climbing performance[END_REF][START_REF] Schoeffl | Evaluation of physiological standard pressures of the forearm flexor muscles during sport specific ergometry in sport climbers[END_REF][START_REF] Sherk | Hormone responses to a continuous bout of rock climbing in men[END_REF]. In 2011, [START_REF] Draper | Self-reported ability assessment in rock climbing[END_REF] published a paper highlighting such discrepancies and the resultant problems consequently arising for researchers attempting to make comparisons between studies. However, since that paper was published, the inconsistency in reporting has continued [START_REF] Amca | Effect of hold depth and grip technique on maximal finger forces in rock climbing[END_REF][START_REF] Laffaye | Upper-limb power test in rock-climbing[END_REF][START_REF] Morenas Martín | Description of the finger mechanical load of climbers of different levels during different hand grips in sport climbing[END_REF][START_REF] Woollings | Incidence, mechanism and risk factors for injury in youth rock climbers[END_REF][START_REF] Young | Not so risky business: The use of planning within rock climbing[END_REF]. The climbers, coaches and researchers present at the 2014 International Rock Climbing Research Congress developed this position statement as a call to all involved in climbing research to follow a consistent method for reporting climber characteristics, nomenclature for ability grouping and to propose the use of one IRCRA scale in all statistical analyses. Such an approach will improve consistency in the field and facilitate comparison between studies.

Climbing scales and recommendations for statistical analysis

As can be seen from Table I, there are a variety of climbing scales used around the world and also for different disciplines. The Yosemite Decimal System (YDS) is used in the USA. The French/sport scale is used for sport climbing in Europe. The British technical grading scale, usually used in conjunction with an adjectival scale, is used to express the difficulty of traditional routes, where equipment is placed into the rock en route to protect the lead climber against a fall during ascent. The Ewbank scale is primarily used in Australia, New Zealand and South Africa, while the Union Internationale des Associations d'Alpinisme scale (UIAA) is primarily used to describe difficulty of short rock routes in Germany, Austria, Switzerland, Czech Republic, Slovakia and Hungary. The Vermin (V) and Font (Fontainebleau) scales are used to describe the difficulty of a bouldering climbing problem.

As can be seen from Table I, the climbing scales are subdivided by letters or +/-grades or are incomplete scales and as such make direct statistical analysis challenging. To overcome this difficulty, researchers have developed number-based scales, converting traditional climbing scales to numberbased scales for statistical analyses [START_REF] Draper | Flexibility assessment and the role of flexibility as a determinant of performance in rock climbing[END_REF][START_REF] Llewellyn | Individual differences and risk taking in rock climbing[END_REF][START_REF] Michailov | Anthropometric and strength characteristics of world-class boulderers[END_REF][START_REF] Padrenosso | Somatic and functional profile of sport rock climbers[END_REF][START_REF] Scho ¨ Ffl | The UIAA medical commission injury classification for mountaineering and climbing sports[END_REF]. The problem with this approach is that, again, there has been little consistency between methods. The first to develop such a scale were [START_REF] Watts | Anthropometric profiles of elite male and female competitive sport rock climbers[END_REF] and this is presented in the Table for reference, however as an incomplete scale (the scale starts at 5.6 YDS rather than 5.1) it could not be used as a statistical scale for all rock climbing studies. The Ewbank and UIAA Decimal scale also had potential, however, both are incomplete scales, the Ewbank additionally starting at level 4. The Sport and YDS scales, the most widely used scales, have 32 grades and as such the Ewbank and UIAA decimal, having only 28 grades, would make conversion to either of these scales problematic. As a consequence the IRCRA scale, also shown in Table I andFigure 1, is proposed as the recommended scale to use for statistical analyses in future studies, as one that matches the number of grade steps in the most commonly used climbing scales. As can be seen from Figure 1, all existing scales, at least at higher difficulty levels, show a linear relationship with the IRCRA scale.

Ability grouping

In the climbing grades paper written by Draper and co-workers (2011b), the authors highlighted inconsistencies in language and ability grouping criteria used to describe climbers and the problems these cause when attempting to make comparisons between studies [START_REF] Boschker | Memory for the functional characteristics of climbing walls: perceiving affordances[END_REF][START_REF] Esposito | Electrical and mechanical response of finger flexor muscles during voluntary isometric contractions in elite rock-climbers[END_REF][START_REF] Grant | Anthropometric, strength, endurance and flexibility characteristics of elite and recreational climbers[END_REF][START_REF] Grant | A comparison of the anthropometric, strength, endurance and flexibility characteristics of female elite and recreational climbers and non-climbers[END_REF] ascended between 5 and 49 climbs in an unnamed group and would not differentiate between climbers who have climbed 50 routes and those with thousands. While this would not matter for the particular study reported by Young and colleagues (2014), it does not help readers to draw conclusions of findings between studies.

In a paper published in Wilderness and Environmental Medicine, Folkl stated (2013, p. 155):

At the time of study design there was no known consensus regarding an appropriate approach to stratifying survey respondents based on level of difficulty climbed. Therefore, for the purposes of this report respondents were asked to categorize themselves as, on average, able to climb 5.0-5.9, 5.10a-5.10d, 5.11a-5.11d, 5.12a-5.12d, 5.13a-5.13d, or 5.14a and above. This statement, not only identifies a further novel approach to classifying climbers, it also highlights the case for reaching consensus detailed in this IRCRA position statement. The consensus reached in this paper will enable future researchers to refer to an agreed system of categorising climber abilities and to employ a common language as descriptors for specific ability groups. [START_REF] Draper | Self-reported ability assessment in rock climbing[END_REF] created two tables of climber abilities, one for males and one for females. During the process of reaching the consensus for this position statement members of the IRCRA discussed the merits of having separate classifications of ability for male and female climbers. While there were a number of researchers and climbers who supported the notion of one table for all, the consensus suggested we should take note from previous research outside the field which sees separate fitness results, tables and performance records (such as athletics world records) for males and females. Rather than creating two tables as was the case for [START_REF] Draper | Self-reported ability assessment in rock climbing[END_REF], for ease of comparison, Table I presents the groups and breakpoints between group for males and females in one table.

Climber characteristics: capturing the group

A further key aspect in reporting both climber abilities and the characteristics of climbers relates to which aspects should be reported. Again we see wide discrepancies between studies and this can be very problematic for making comparison between studies (Bala ´s ˇ, Pecha, [START_REF] Bala ´s | Hand-arm strength and endurance as predictors of climbing performance[END_REF][START_REF] Donath | Work-relief ratios and imbalances of load application in sport climbing: Another link to overuse-induced injuries? Scandinavian[END_REF][START_REF] Fanchini | Differences in climbing-specific strength between boulder and lead rock climbers[END_REF][START_REF] Fryer | A psychophysiological comparison of on-sight lead and top rope ascents in advanced rock climbers[END_REF][START_REF] Green | The impact of fear words in a secondary task on complex motor performance: A dual-task climbing study[END_REF][START_REF] Schoeffl | Evaluation of physiological standard pressures of the forearm flexor muscles during sport specific ergometry in sport climbers[END_REF][START_REF] Scho ¨ Ffl | Acute injury risk and severity in indoor climbing-a prospective analysis of 515,337 indoor climbing wall visits in 5 years[END_REF]. In addition to the normal data collected such as age, gender, body mass and height, to better inform readers of future research papers and to facilitate comparison between studies a number of regular characteristics should be reported by authors. It should be noted that the classification of climbers in Table I relates to their highest self-reported redpoint ascent. A redpoint, from the German rotpunkt, refers to a successful lead climb ascent, without weighting the rope, of a previously practised route. Previous research by Draper et al. (2011a) indicates that the use of self-report grades is appropriate as climbers have been shown to accurately self-report their climbing ability in a research context.

A number of IRCRA members highlighted the need for clarity regarding what would constitute a highest redpoint grade, for instance as Fanchini (2014) stated, would making a successful ascent of one route which suited a particular climber's characteristics (anthropometry etc.) constitute a fair and accurate assessment of their ability? Drum (2014) proposed an excellent solution for reporting the 3:3:3 rule. When completing the climbing ability assessment, researchers should record the climber's highest redpoint grade for which they have completed 3 successful ascents on 3 different routes (at the grade) within the previous 3 months. For ease of comparison, this should be reported as local grade as well as sport/French, YDS and IRCRA. By way of example, as can be seen from Table I, a study in South Africa might report findings for a group of advanced level female climbers with a mean self-reported ability of 23 Ewbank (7a sport/French, 5.11d YDS, IRCRA 17). While for an equivalent group of boulderers (female advanced level), the mean climbing grade might be V6 (Font 7a, IRCRA 20). In addition, as a minimum, researchers should report answers to the following questions about the following characteristics of the climbers in a study to improve comparability between studies:

• Climbers' self-identity in the sport -how they see themselves in terms of predominant discipline (i.e. boulderer, sport climber, etc.)? • Disciplines (i.e. bouldering, sport, traditional etc.) the climbers take part in (percentage of time devoted to each) in the past 3 to 12 months (include data for both time periods)?

•

Future research

Table I provides a conversion between climbing grade scales used in different countries or regions of the world. Those involved with climbing know that although these appear objective when viewed in a table such as this, the grading of a particular route is inherently more subjective in nature.

Although perhaps made more objective over time through repeat ascents and confirmation (or often down-grading) of the original grade, there remains an element of subjectivity to grade assignment for any particular route. Conversion between scales, such as from YDS to Ewbank, should therefore be completed with some caution. Likewise, while the IRCRA scale might appear to represent a ratio scale and was developed in an objective manner, conclusions drawn in regard to the ability of climbers should, at this stage, also be made with some reservation. Furthermore, scales such as the British adjectival scale, appear to have psychological barriers which have arisen, often through climbing folklore, around specific grades. These may well affect the rate at which climbers move through grades, or appear to have sticking points in their progression due to such barriers. EXamples of this might include the E1, the first 'extreme' grade climb in traditional climbing, the 21 grade in Australia using the Ewbank scale or the 5.13 YDS grade. This raises two issues in this aspect of climbing research that, perhaps, merit further attention. Firstly, research into the presence of certain psychological 'sticking points' could usefully be undertaken in the near future. It may be likely that the steps between grades are not of a ratio scale nature, but more likely ordinal and should perhaps therefore be treated as such, which has implications for further statistical analyses. Secondly, it would seem beneficial, in attempting to quantify the ability of climbers to (a) agree on a battery of valid and reliable measures of climbing ability and then to (b), using a large sample of climbers across a range of abilities, assess performance on this battery of tests to create a more objective measure of climbing ability for use in future studies. Members of the IRCRA are in the process (April 2015-April 2016) of completing a multi-centre collaborative research project to accomplish such a large-scale study. The research is designed to identify valid and reliable measures of climbing ability and to examine the extent to which these can be utilised together to create a more objective measure of climbing ability. Researchers interested in being involved in this study should contact the corresponding author of this paper for details.

Conclusion

The increasing research attention on the sport of rock climbing highlights very clearly the continued discrepancies in reporting methods and approaches to statistical analysis evident between studies. The IRCRA scale, shown in Table I, has been developed to support a common approach to statistical analyses. In addition, the ability grouping nomenclature also detailed in Table I, along with the recommendations for reporting climber characteristics, if applied in reporting future studies will substantially increase the uniformity between papers and improve ease of comparison for readers. It is suggested that all future researchers follow the recommendations presented in this position statement and refer to Table I for statistical analysis and classification of the climbers in their studies.

Disclosure statement

No potential conflict of interest was reported by the authors.

  TableI. Ability grouping for males and females and a range of reporting scales shown alongside the IRCRA scale.Note: IRCRA stands for the International Rock Climbing Association; YDS for Yosemite Decimal System; BRZ for Brazilian scale, UIAA for the Union Internationale des Associations d'Alpinisme and Font for Fontainebleau. Sources:[START_REF] Watts | Anthropometric profiles of elite male and female competitive sport rock climbers[END_REF],[START_REF] Benge | Rock: Tools and technique[END_REF],[START_REF] Draper | Self-reported ability assessment in rock climbing[END_REF][START_REF] Scho ¨ Ffl | The UIAA medical commission injury classification for mountaineering and climbing sports[END_REF][START_REF] Bmc | A brief explanation of UK traditional climbing grades[END_REF],Rockfax (n.d.), The American Alpine Club (2012).

  [START_REF] Draper | Self-reported ability assessment in rock climbing[END_REF] proposed the nomenclature for climbing ability as shown in TableI, establishing five groups from low grade to higher elite level climbers. Despite the publication of the paper by[START_REF] Draper | Self-reported ability assessment in rock climbing[END_REF], studies continue to be published with inconsistencies in the language used to describe the groups in their studies. By way of recent examples,[START_REF] Laffaye | Upper-limb power test in rock-climbing[END_REF] categorised their climbers as novice (<6a), skilled (6c-7b) or elite (≥8a) while[START_REF] Lechner | A climbing hold with an integrated three dimensional force measurement and wireless data acquisition[END_REF] classified climbers as experienced or less experienced without stating the grounds upon which the categorisation was made. In 2014 Young et al. again used the experienced or inexperienced categorisation, however, in this study they classified each as having ascended more than 50 vertical climbs or fewer than 5 vertical ascents, respectively. While not of relevance to their study, this categorisation would leave a middle group of climbers who

Figure 1 .

 1 Figure 1. IRCRA Reporting Scale against existing difficulty scales; IRCRA stands for the International Rock Climbing Association; YDS for Yosemite Decimal System; BRZ for Brazilian scale, UIAA for the Union Internationale des Associations d'Alpinisme and Font for Fontainebleau.

  Percentage of time spent climbing indoors or outdoors in the past 3 months and over the past 12 months? • Mean time (days per week and hours per session) spent climbing/training in a typical week in past 3 months and in the past 12 months? • Time in the sport -the number of years/months experience? • Are they involved in competition climbing, along with the disciplines and levels (i.e. bouldering, local vs. national competitions)? • Additionally researchers might report the climbers' preference for style of ascent, (i.e. onsight, redpoint, top-rope) and for terrain (vertical, overhanging, slab climbing, varied).


Fairouz Aberkane
email: fairouz.aberkane@univ-batna.dz

Nadia Zine

Abdelhamid Errachid

Abdelhamid Elaissari

Keywords: Poly(4-vinylpyridine), Cubic gold nanoparticles, Thioether oligomer, Dodecanethiol, Radical polymerization

In the present research work, we report a facile, in-situ, and seedless-based synthesis method of cubic gold nanoparticles at room temperature by using thioether oligomer ligand DDT-poly(4-vinylpyridine) as a functionalization and stabilization agent. Thioether oligomer ligand was synthesized by bulk radical polymerization in the presence of dodecanethiol, while, the synthesis of cubic gold nanoparticles was carried out by a reduction reaction by NaBH 4 in the presence of the pre-synthesized thioether oligomer ligand. The effect of stirring conditions on the growth of nanoparticles and their final morphology has been investigated. Synthesized thioether oligomer ligand and gold nanoparticles were thoroughly characterized using numerous techniques such as Size exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance spectroscopy ( 1 H NMR), Transmission Electron Microscope (TEM), and UV Visible spectroscopy.

Cubic gold nanoparticles synthesis by in situ generation of seeds by chemical method in the presence of an oligomer thioether DDT-Poly(4vinylpyridine)

Introduction

Anisotropic gold nanoparticles (AuNPs) are of increasing interest in many fields, because of their shape-dependent properties, in particular for medical fields [START_REF] Murphy | Anisotropic Metal Nanoparticles : Synthesis , Assembly , and Optical Applications[END_REF][2] [START_REF] Kohout | Anisotropic Gold Nanoparticles in Biomedical Applications[END_REF]. These nanostructures have fascinating applications as photo-thermal therapy [START_REF] Yingxin | Preparation of novel anisotropic gold nanoplatform as NIR absorbing agents for photothermal therapy of liver cancer and enhanced ultrasound contrast imaging Preparation of novel anisotropic gold nanoplatform as NIR absorbing agents for photothermal therapy of liver cancer and enhanced ultrasound contrast imaging[END_REF][START_REF] Hen | Anisotropic scattering characteristics of nanoparticles in different morphologies : improving the temperature uniformity of tumors during thermal therapy using forward scattering[END_REF], drug delivery [START_REF] Brandelli | Bioactivity of noble metal nanoparticles decorated with biopolymers and their application in drug delivery[END_REF] [START_REF] Singh | Biomineralized Anisotropic Gold Microplate -Macrophage Interactions Reveal Frustrated Phagocytosis-like Phenomenon : A Novel Paclitaxel Drug Delivery Vehicle[END_REF], biological imaging [START_REF] Peng | Recent Advances in Optical Imaging with Anisotropic Plasmonic Nanoparticles Recent Advances in Optical Imaging with Anisotropic Plasmonic Nanoparticles[END_REF] [START_REF]Background-Free Imaging of Viral Capsid Proteins-Coated Anisotropic Nanoparticle on Living Cell Membrane with Dark-Field Optical Microscopy[END_REF], chemical detection [START_REF] Manuscript | [END_REF] [START_REF] Jin | Sensors and Actuators B : Chemical Eco-friendly colorimetric detection of mercury ( II ) ions using label-free anisotropic nanogolds in ascorbic acid solution[END_REF], and chemical catalysis [START_REF] Premkumar | Shape-tailoring and catalytic function of anisotropic gold nanostructures[END_REF] [START_REF] Sahoo | Microwave-assisted synthesis of anisotropic gold nanocrystals in polymer matrix and their catalytic activities[END_REF].

Much effort on the development of new methodologies for the synthesis of anisotropic AuNPs has been provided over the last decade, in which the final reaction conditions of AuNPs synthesis have been optimized. Anisotropic AuNPs can be synthesized by seed and seedless methods, both strategies are classified as chemical methods, these methods allow better control of the size, morphology, and surface chemistry of nanoparticles, such as coating and functionalization [14] [START_REF] Ortiz-Castillo | Anisotropic gold nanoparticles : A survey of recent synthetic methodologies[END_REF]. In the seedless method, the nucleation and growth steps occurred at the same time, however, the seed-based method separates the nucleation and growth steps during the synthesis of nanoparticles by introducing small pre-synthesized core particles into a growth solution typically containing a metal precursor, a reducing agent, surfactant, and certain additives such as polymers [START_REF] Ortiz-Castillo | Anisotropic gold nanoparticles : A survey of recent synthetic methodologies[END_REF]. Generally, polymers are used as functionalization and stabilization agents, in absence of stabilization the aggregation of nanoparticles causes the loss of their plasmonic properties and therefore their interesting applications [START_REF] Saldías | The Role of Polymers in the Synthesis of Noble Metal Nanoparticles[END_REF]. The seed-based method has been demonstrated as a powerful synthetic route to generate a range of different anisotropic metal nanoparticles such as nanorods [START_REF] Gole | Seed-Mediated Synthesis of Gold Nanorods : Role of the Size and Nature of the Seed[END_REF], nanoprisms [START_REF] Millstone | Controlling the Edge Length of Gold Nanoprisms via a Seed-Mediated Approach[END_REF], nanostars [START_REF] Phiri | Seedless gold nanostars with seed-like advantages for biosensing applications[END_REF], and nanocubes [START_REF] Thiele | Gold nanocubes -Direct comparison of synthesis approaches reveals the need for a microfluidic synthesis setup for a high reproducibility[END_REF].

Using Polymers in the nanoparticles synthesis process is very important; the dual role of polymer (functionalization and stabilization) in the synthetic method eliminates the need for an additional surfactant [START_REF] Shan | Recent advances in polymer protected gold nanoparticles : synthesis , properties and applications[END_REF]. The combination of the properties of nanoparticles (e.g., optical) and macromolecules provides a possibility to prepare composite materials with unique properties compared to the individual nanoparticle and polymer [START_REF] Adokoh | Synthesis and evaluation of glycopolymeric decorated gold nanoparticles functionalized with goldtriphenyl phosphine as anti-cancer agents[END_REF] [START_REF] Banu | Biology Doxorubicin loaded polymeric gold nanoparticles targeted to human folate receptor upon laser photothermal therapy potentiates chemotherapy in breast cancer cell lines[END_REF].

Polymers containing functional groups with a high affinity for noble metal surfaces, and more especially thiol functionalities react with the AuNPs surfaces to form chemical interactions [START_REF] Zhou | A facile synthesis of aliphatic thiol surfactant with tunable length as a stabilizer of gold nanoparticles in organic solvents[END_REF]. Sulfur-containing polymers, which carry functional groups at one end of a polymer chain, or in the middle, such as thioacetate [START_REF] González-Fernández | Copolymers with acetyl-protected thiol pendant groups as highly efficient stabilizing agents for gold surfaces[END_REF], disulfide [START_REF] Boudon | Liquid-Crystalline Thiol-and Disulfide-Based Dendrimers for the Functionalization of Gold Nanoparticles[END_REF], thiol [START_REF] Jang | Gold nanorod-photosensitizer complex for near-infrared fluorescence imaging and photodynamic/photothermal therapy in vivo[END_REF], and thioether [START_REF] Hussain | Size-Controlled Synthesis of Near-Monodisperse Gold Nanoparticles in the 1 -4 nm Range Using Polymeric Stabilizers Size-Controlled Synthesis of Near-Monodisperse Gold Nanoparticles in the 1-4 nm Range Using Polymeric Stabilizers[END_REF], has been used for the synthesis of AuNPs. Polymer thioether ligands are widely used as polymeric stabilizers to prepare uniform metallic nanoparticles. Multiple thioether-metal interactions can lead to stable and ordered monolayers on metal surfaces.

They are a very useful system for the functionalization of nanoparticles for several applications [START_REF] Razzaque | Design and utility of metal/metal oxide nanoparticles mediated by thioether end-functionalized polymeric ligands[END_REF] [START_REF] Niu | Dendrimer-encapsulated metal nanoparticles and their applications to catalysis[END_REF]. The advantage of these products lies in their weak interactions with the surface of the nanoparticles, which allows them to be easily replaced by other ligands [START_REF] Razzaque | Design and utility of metal/metal oxide nanoparticles mediated by thioether end-functionalized polymeric ligands[END_REF]. In comparison with other approaches using polymers as stabilizing and functionalizing agents, thioether polymers lead to the formation of nanoparticles of spherical morphology, which exhibit a significantly uniform monodispersity with small particle size. Xin Huang, et al. describe an approach to generate spherically and fairly uniform AuNPs with diameters about 2 -6 nm using thioether end-functional polymer ligands dodecanethiol (DDT)poly(vinyl acetate) as the stabilizing agents [START_REF] Huang | Facile preparation of size-controlled gold nanoparticles using versatile and end-functionalized thioether polymer ligands[END_REF]. Wang et al. reported a one-step aqueous preparation of highly monodisperse AuNPs with diameters less than 5 nm using thioetherfunctionalized polymer ligands: DDT-poly(acrylic acid), DDT-poly(methacrylic acid), DDTpoly(vinylsulfonic acid), DDT-poly(vinylpyrrolidone), DDT-poly(hydroxyethyl acrylate), and DDT-poly(ethyleneglycol methacrylate) [START_REF] Wang | Design of Polymeric Stabilizers for Size-Controlled Synthesis of Monodisperse Gold Nanoparticles in Water[END_REF].

In the present work, cubic AuNPs were synthesized by a seedless method using a pre-synthesized oligomer containing a thioether functionality in its chains, DDT-Poly(4vinylpyridine). In this method nucleation and growth of nanoparticles are produced in a single phase in an organic medium (DMF) at room temperature. The effect of stirring conditions on the growth of nanoparticles and their final morphology has been investigated.

Using measurements by SEC, 1 H NMR, FTIR, TEM, UV-Visible spectroscopy, synthesized products; thioether oligomer ligand and AuNPs have been characterized.

Materials and methods

Materials

4-Vinylpyridine (4VP, ≥95%); Tetrachloroauric acid (HAuCl 4 .3H 2 O, 99.999%); Dimethylformamide (DMF, ≥99.8%) and Hexane (≥95%) were purchased from Sigma-Aldrich.

1-Dodecanethiol (DDT, >97%) and benzoyl peroxide (BPO, >97%) were obtained from Fluka.

Sodium tetrahydroborate (NaBH 4 98%) and diethyl ether (99,5%) were obtained from Riedel-deHaën. All reagents were used as obtained except monomer and initiator; 4VP was purified by vacuum distillation (colorless liquid was obtained) and BPO was purified via the recrystallization process in Methanol.

Experimental methods

Size exclusion chromatography (SEC) was used to determine the average weight and the polydispersity index of the prepared oligomer. An AGILENT 1200 series isocratic pump equipped with an AGILENT 1200 series automatic switch and a set of columns, was used for the analyzes. Detection was performed by an AGILENT 1260 Infinity refractometer. A PC driver set and retreat the results using two software programs: Agilent Chemstation (for pump control) and Astra V version 5.3.4.14 (to acquire and interpret the results). The infrared spectrum of synthesized thioether oligomer was recorded on Nexus 470 FTIR spectrometer in a total Reflexing attenuated on Crystal of Diamond in mono-reflexion (Smart-orbit, Thermo Scientific). The spectral range is from 4000 to 400 cm -1 , with 256 scans and 4 cm -1 of resolution. The detector is a DTGS (Deuterated Tri-Glycine Sulfate). A Bruker AV400 MHz spectrometer was used to recorde 1 H NMR spectrum. Analysis was carried out in DMSO at room temperature using the δ scale and tetramethylsilane (TMS) as an internal standard. The chemical shift were given in ppm relative to tetramethylsilane. UV-Visible characterization of AuNPs dispersions was performed using a UV-Visible spectrophotometer (UV-1700, Shimadzu). The absorbance measurements were made over the wavelength range of 400-700 nm using 1 cm path length quartz cuvettes. Transmission Electron Microscopy (TEM) was performed with a Philips CM120 microscope. A droplet of the suspension was deposited on a microscope grid (copper support covered with carbon) and slowly dried in open air. The dry samples were observed by TEM under 100 kV acceleration voltages.

Experimental

Synthesis of functional thioether oligomer ligand

Oligomer synthesis reaction was carried out as described previously [START_REF] Aberkane | Electrochemical Sensor Based on Thioether Oligomer Poly ( N-vinylpyrrolidone ) -modified Gold Electrode for Bisphenol A Detection[END_REF]; 2 mL of monomer (4VP, 18.83 mmol), 1.2 mL of Dodecanethiol (DDT, 5 mmol), and 10 mg of benzoyl peroxide (BPO, 0.0413 mmol) were mixed. The mixture was degassed for 30 min using an ultrasonic apparatus to remove the oxygen dissolved in the solution, then placed in a preheated oil bath. The temperature of the reaction mixture was maintained between 100-110˚C and heated for 48 h. After cooling, viscous product, red in color, was obtained. The synthesized oligomer was isolated by dissolving the reaction mixture in methanol and precipitating it into diethyl ether. This step was repeated several times for removing the unreacted monomer. Oligomer thus obtained was dried, at ambient temperature, then at 50˚C to a constant weight. The yield of the obtained thioether oligomer DDT-P4VP was 55.62%.

Preparation of cubic AuNPs using thioether oligomer ligand

Cubic AuNPs, stabilized by oligomeric thioether ligands, were synthesized according to the following method; firstly, all glassware was rinsed with aqua regia (HNO 3 /HCl: 1V/3V) and several times with Milli-Q water. Afterward, 45.2 mg of the oligomer (DDT-P4VP) was introduced in 10 mL of HAuCl 4 solution (1 mM in DMF). The reaction mixture was stirred with a magnetic stir for 24 h in dark conditions. The reduction reaction of Au +3 ions is carried out by the dropwise addition, under stirring (700 rpm), of 1 mL of a freshly prepared aqueous solution of NaBH 4 (0.1 M). The solution color changed from pale yellow to dark with a deep purple to a red color indicating the formation of AuNPs. Thereafter, stirring is stopped and the solution is kept in the dark for complete growth of the cubic AuNPs. Finally, the prepared nanoparticles were purified by centrifugation (at 10.000 rpm) and redispersed in DMF.

Results and discussion

Synthesis and characterization of thioether oligomer ligand

The DDT-4NVP thioether oligomer was synthesized by the process of radical bulk polymerization of 4VP in the presence of DDT as a chain transfer agent (Scheme 1). The polymerization reaction is initiated by a thermal initiator (BPO) at a temperature between 100 110 ˚C for 48 hours. In reality, DDT also can contribute to the initiation of polymerization; sulfur has a high affinity with radicals and can easily lose the hydrogen from thiol by transfer reaction and give rise to the formation of the sulfide radical. The reactive fragments resulting from the decomposition of DDT can also initiate polymer chains [32][33]. Since the amount of DDT is much higher compared to the initiator (BPO), the initiation comes mainly from thiol fragments. The molecular weight of the DDT-P4VP oligomers was determined using size exclusion chromatography (SEC). The weight average molecular mass (Mw) of DDT-P4VP was 745 g/mol compared to standard polystyrene, with a polydispersity index of 1.06. The calibration is carried out with four standard polystyrenes of increasing masses (380, 1020, 1860, 2698 g/mol). However, the slightly narrow molecular weight distributions, are due to the radical polymerization technique used which greatly resembles controlled radical polymerization. Also, the molecular weight of 4VP is 105.14 g/mol, which means that the degree of polymerization of the obtained oligomer is approximately 5. Wavenumbers (cm -1 )

The 1 H NMR spectrum of DDT-P4VP is shown in Figure 2. Proton peaks presented at δ = 8.27 and 6.59 ppm correspond to the H 7 and H 6 protons of pyridinium group in 4VP, respectively, the main chain methine (H 5 ) and methylene protons (H 4 ) are assigned in the range of 1.32-1.77 ppm [START_REF] Huang | Synthesis and Characterization of Polystyrene-b-Poly ( 4-vinyl pyridine ) Block Copolymers by Atom Transfer Radical Polymerization Synthesis and Characterization of Polystyrene-b-Poly ( 4-vinyl pyridine ) Block Copolymers by Atom Transfer Radical Polymerization[END_REF]. Signals located at 0.84, 1.22, and 2.52 ppm are attributed to the aliphatic protons of the DDT fragment, linked to the chain end of the oligomer, H 1 , H 2 and H 3 respectively [START_REF] Jayabharathi | [END_REF]. Both the FTIR and 1 H NMR spectra indicated that the synthesis of DDT-P4VP was accomplished successfully.

Preparation and characterization of cubic AuNPs

Thioether oligomer was synthesized, by the bulk radical polymerization method, in the presence of a transfer agent (DDT). The use of the transfer agent was to have sulfur in the oligomer chain; sulfur can produce interactions with the surface of AuNPs because of its affinity with noble metals [36][37]. In this part, we report the synthesis and functionalization of AuNPs in an organic medium (in DMF). The selected solvent is a good solvent for gold salt and the oligomer ligand. Here, the DMF solvent is miscible with water, so both solutions of the reducing agent and gold ions form a single phase. The functionalization of the AuNPs was carried out during synthesis by introducing the oligomer into the reaction mixture (Scheme 2). The presence of several nitrogen atoms along the polymer chain, in the pyridine moieties more than sulfur atoms, leads us to think that several contact points between the nitrogen atoms and the nanoparticles can be formed and help the oligomer to attach to the surface of the nanoparticles after reduction reaction. These pyridine moieties can create multiple interactions on the surface of the metal and lead to electrostatic and steric stabilization [START_REF] Li | Reverse micelles of star-block copolymer as nanoreactors for preparation of gold nanoparticles[END_REF] as shown in scheme 2.

Scheme 2: Cubic AuNPs synthesis reaction with the proposed morphology of the obtained DDT-P4VP stabilized AuNPs.

In general, the mechanism of nanoparticles formation passes through successive steps of nucleation and growth. Several parameters are responsible for the final shape of nanoparticles. At the growth step, stabilizers, surfactants, shaping agents, and growth kinetics determine the final shapes of the resulting nanoparticles. The TEM image (Figure 4)

shows the presence of cubic-shaped nanoparticles in addition to small spherical-shaped nanoparticles, which confirms that the nucleation of nanoparticles begins with the formation of spherical nuclei, and the growth of nanoparticles, under specific conditions, leads to the formation of cubic AuNPs. Without stirring and in the presence of an oligomer, that has pyridine fragments, helps the growth of the spherical nanoparticles into cubic nanoparticles. This phenomenon is noticed, likewise, in the case of gold nanorods synthesis, which requires that the stiring be suspended after the addition of the reducing agent to promote the growth and progression of the nanorods in a single dimension. The mean diameter of the obtained cubic AuNPs and its polydispersity index (PDI) were calculated by averaging over 90 particles from the TEM images using ImageJ software, the average diameter is 47.95 nm with a PDI equal to 0.3. The obtained AuNPs are cubic in shape and relatively uniform. Consequently, thioether oligomer ligand DDT-P4VP acts simultaneously as a stabilizing and shaping agent. The interaction of AuNPs with light leads to a phenomenon called surface plasmon resonance (SPR), which results in strong absorption in the visible region between 500 nm and 800 nm depending on the size and shape of the nanoparticles, which can be measured by UV-Visible spectroscopy. The UV-Visible spectrum of the resulting cubic AuNPs presented in Figure 6 shows a distinct plasmon resonance peak. The maximum wavelength (λmax) was found at 551.43 nm, this wavelength is well within the range generally observed for cubicshaped AuNPs [39][40]. However, the UV-Visible spectrum of the obtained spherical AuNPs (Figure 6) shows an intense absorption peak at 517 nm. Optical properties such as absorption maxima and absorption intensity usually depend on the size of the nanoparticles. An intense absorption peak is, in general, attributed to the surface plasmon excitation of small spherical particles [START_REF] Abdelhalim | Physical Properties of Different Gold Nanoparticles : Ultraviolet-Visible and Fluorescence Measurements[END_REF].

Conclusion

In this work, an oligomeric ligand containing thioether function in its chain (DDT-P4VP) was synthesized and used as a functionalization and stabilization agent for AuNPs.

Thioether oligomer ligand was synthesized by bulk radical polymerization in the presence of dodecanethiol, while, the synthesis of AuNPs was carried out using seedless-based synthesis method, by a reduction reaction in an organic medium (DMF) and at room temperature. The effect of the stirring condition on the growth of nanoparticles and their final morphology has been studied. The obtained results showed that stirring condition is an important factor to obtain a specific shape; synthesis reaction with a continuous stirring involves sphericalshaped AuNPs with fairly uniform and small size (3.55 nm), however, without stirring cubic AuNPs with a relatively large size (47 nm) were obtained. These results indicate that the thioether oligomeric ligand DDT-P4VP can act as a shaping agent for AuNPs. Synthesized thioether oligomer ligand and AuNPs were thoroughly characterized using numerous techniques such as SEC, FTIR, 1 H NMR, TEM, and UV-Visible spectroscopy.

Scheme 1 .

 1 Scheme 1. Polymerization reaction of 4VP in the presence of DDT.

Figure 1 .Figure 1 .

 11 Figure 1. FTIR spectra of 4VP and the obtained DDT-P4VP polymer.

Figure 2 . 1 H

 21 Figure 2. 1 H NMR spectrum of synthesized thioether oligomer DDT-P4VP.

Figure 4 .

 4 Figure 4. TEM image of cubic AuNPs prepared using thioether oligomer ligand DDT-P4VP.

Figure 5 .

 5 Figure 5. TEM images of spherical AuNPs prepared in presence of thioether oligomer ligand DDT-P4VP.

Figure 6 .

 6 Figure 6. UV-Visible absorption spectra of cubic AuNPs and spherical AuNPs prepared in presence of DDT-P4VP oligomeric ligand in DMF.