bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viscosity Profiles of Printing Thickeners at High Shear Rates and Their Use in Predicting Paste Flow in Screen Printing
Authors: Guion T.H. , Hood J.R. 
Published: March 2008

Apparent viscosities of various natural and synthetic printing thickeners were measured at shear rates from 0.05 to 7000 s-1. Log viscosity-log shear rate plots (viscosity profiles) were curves, not straight lines as generally believed. Nonlinear regression equations were computed and required significant second or third order terms or both to fit the data. The slopes and shapes (or curvature) of the profiles were distinctly different for synthetic copolymers, for nonionic cellulose or starch ethers, and for anionic polysaccharides (either carboxylmethyl cellulose or sodium alginate). The interaction efforts on both apparent viscosity and slope of viscosity profiles of such variables as pH, temperature, concentration of thickener and added electrolyte, thickener composition, and molecular weight were estimated by analysis of variance. The appearance of prints made with different thickeners was compared visually, photometrically, and microscopically. Prints with optimum sharpness of mark, levelness, and penetrations were obtained from pastes whose profiles, even with widely different shapes, all intersected at the same shear rate and apparent viscosity. The concentrations of each thickener required for optimum paste spread and appearance could be calculated from the slope of the viscosity profiles and from the estimated change in viscosity with concentration.
Factors Controlling Formaldehyde Release from Durable Press Cotton
Authors: Kamath Y.K. , Weber R.U. , Hornby S.B. , Weigmann H.-D. 
Published: March 2008

Formaldehyde release from durable press fabrics treated with dimethyloldihy droxyethyleneurea (DMDHEU) has been investigated in an effort to understand the physicochemical equilibria that control the generation of formaldehyde and its transport from the fabric to the environment. Fabric pH plays a major role in the generation of pendant N—CH20H groups and of formaldehyde by affecting the rates of hydrolysis of the crosslinks formed between cellulose and the finish and of the pendant N—CH2OH groups, respectively. Specific rate constants for the hydrolysis of C-O and C-N bonds have been determined and found to go through a minimum at pH 7, suggesting that formaldehyde release under neutral conditions is very low. Under acid conditions, a high rate of crosslink hydrolysis (C-O scission) and a proportionately low rate of N—CH20H hydrolysis lead to the generation of additional N-CH2OH groups, increasing the formaldehyde release potential of the fabric. Under alkaline conditions, on the other hand, a combination of high C—N and low C—O hydrolysis rates leads to the elimination of N—CH2OH groups, the potential sources of formaldehyde release in the fabric. The sorption equilibrium does not play a major role in formaldehyde release into water, but in a confined gas phase, formaldehyde release to the environment is controlled by the distribution coefficient of formaldehyde between cellulose and air. At ambient temperatures, the distribution coefficient is very large, reflecting the high affinity of formaldehyde for cellulose at low temperatures. Heats of sorption obtained from sorption studies at various temperatures suggest chemisorption of formaldehyde, possibly involving the formation of hemiacetals with cellulose. Since hemiacetals are hydrolytically unstable, formaldehyde is released under conditions of high humidity. At high treatment temperatures, formaldehyde binds with cellulose in an irreversible manner, forming a product that is stable to mild hydrolytic conditions, and is thus removed from the sorption equilibrium.
Surface Energy Analysis of the Detergency Process — Surface Tension Components of Binary Mixtures of Organic Liquids and Aqueous Solutions of Surfactants
Authors: Otani Mamiko , Saito Masako , Yabe Akihiko 
Published: March 2008

The applicability of the surface energy analysis method to the detergency system is discussed. This method involves multicomponent washing liquids, such as binary mixtures of organic liquids and aqueous solutions of surfactants. The surface tension and its components of these mixtures and surfactant solutions, which were calculated from contact angle measurements, were not linearly proportional to the molar ratio or concentration. Oily dirt/washing liquid interfacial tensions were estimated from surface tension components. The interfacial tension tended to be overestimated compared with that observed in the systems using surface active materials. The results of a rolling-up test of oil drops suggest a correlation between the work of adhesion and washability.
Anisotropy of Wool
Authors: De Jong S. , Curiskis J. 
Published: March 2008

The quantitative relationship is examined between torsion and tensile experiments done on wool fibers at various conditions of humidity and temperature. The relation ship between torsion and tension measurements on a two component fiber depends on the volume fraction of the two mechanically distinct components. The two me chanical phases of the wool fiber are first assumed to be isotropic, but no assumption is made about their volume fraction. On this basis a mechanically elastic phase refers to approximately 5% of the fiber, not about 50% as is sometimes supposed. The re maining 95% of the fiber acts mechanically as a water penetrable viscoelastic matrix. Allowance for anistropy in the mechanically elastic phase does not significantly affect its volume fraction. If the viscoelastic matrix phase is regarded as constituting 95% of the fiber, it can be considered as mechanically isotropic at all water contents. Because of the low filament volume fraction obtained, the results suggest that the microfibril is not the mechanical unit corresponding to the water unaffected phase of the two phase model.
Factors Affecting the Zeta Potential at Wool Fiber Surfaces
Authors: Capablanca J.S. , Watt I.C. 
Published: March 2008

A streaming potential method has been used to determine the zeta potential at the surface of wool fibers in a supporting electrolyte solution. The zeta potential gives a measure of the average charge density at the surface of shear and, when measured as a function of pH, yields a titration curve for the fiber surface. The reproducibility of the curves for a particular wool sample is now such that zeta potential determination provides a means of assessing chemical reactions at the fiber surface through changes in surface charge. The technique has been applied to studies of the chlorine/Hercosett shrinkproofing process. The shapes of the curves and the pH of the isoelectric point can be significantly affected by the choice of cleaning procedures adopted to remove contaminants. In addition, the state of the surface changes with time; this aging process leads to a more negative surface through atmospheric oxidation. Chemical oxidation by acid chlori nation of disulphide groups brings about a large excess of anions and a negative surface. Subsequent modification by deposition of a cationic polymer, as in the chlorine/ Hercosett process, results in a more positive surface. However, the interaction between the polymer and the wool causes the new surface to be less positive than for Hercosett film coated on a glass substrate.
Crosslinking Effects in Reactive Dyeing of Protein Fibers'
Authors: Ball Peter , Meyer Ulrich , Zollinger Heinrich 
Published: March 2008

Dyes featuring two reactive groups or one bifunctional group, when applied to wool and silk, can reduce the solubilities of these fibers in appropriate solvent systems. This is consistent with the formation of crosslinks during dyeing. Of the nine dyes studied, the most effective crosslinker possessed two well separated reactive groups. On wool, dyes with more closely located reactive sites were comparable in effect to formaldehyde. The reduced solubility of wool dyed with dyes containing one α-bromoacrylamide group indicates a bifunctional reaction of this group; this is in agreement with a hy pothesis stating bifunctionality. On silk, α-bromoacrylamide dyes undergo bifunctional reactions to a limited extent only, if at all. With other bifunctional dyes, the number and distribution of cnosslinks on silk depend on the type of reactive group and the method of dyeing. The inhibition of dye penetration after crosslink formation on silk in dyeings with a difluorochlo ropyrimidine dye at 40°C can be greatly alleviated by dyeing at 90°C, and thereby distributing the crosslinks more evenly throughout the fiber. The effectiveness of the highly reactive dichlorotriazine system in crosslinking depends on the method of dyeing used on wool and on silk.
Effect of Different Catalysts on the DMDHEU-Cotton Cellulose Reaction
Authors: Abhyankar Prashant N. , Beck Keith R. , Ladisch Christine M. , Frick John G. 
Published: March 2008

The utility of alkaline hydrolysis as a method for removal of DMDHEU crosslinks from cotton is illustrated in this paper. The method was applied to fabric treated with DMDHEU/MgCl 2 and DMDHEU/MgCl2/citric acid mixed catalyst systems. Removal of the finish was complete as verified by nitrogen and formaldehyde analyses and by wrinkle recovery measurements. Losses in breaking strength and flex abrasion resistance produced in the cotton fabric upon treatment with DMDHEU were almost completely restored by the resin stripping. The DMDHEU/MgCl 2 treatment reduced the dpv (degree of polymerization by viscosity) of cotton by about 24% and DMDHEU/mixed catalyst treatment reduced it by about 18%. The quantity and chemical nature of the catalyst affect the ethyl acetate solubility of cellulose nitrate formed after stripping and nitration of crosslinked samples. Neither of the catalysts alone imparted ethyl acetate insolubility, but each catalyst by itself decreased the degree of polymerization of the cotton cellulose to a significantly greater extent than in the presence of DMDHEU. Fabrics treated with high concentrations of both catalyst systems could not be completely stripped of nitrogen and formaldehyde, and were not soluble in ethyl acetate (after nitration).
Heat Transfer Characteristics of Nonwoven Insulating Materials
Authors: Obendorf S. Kay , Smith Jana P. 
Published: March 2008

The thermal insulating abilities were evaluated using the guarded hot plate technique (ASTM D 1518-77) for the following selected nonwoven insulating materials: air-laid structures of low linear density polyolefin and low linear density polyolefin mixed with conventional linear density polyester, and carded structures of hollow polyester fiber, crimped polyester filament, and conventional polyester fiberfill. The thermal resistance of the materials varied directly with thickness, but on a per thickness basis the air-laid structures provided more thermal resistance than the carded structures. The thicker, low linear density, air-laid structure was an exception in that it did not exhibit as large an advantage over the carded structures as did the other air-laid struc tures. Under the conditions of the guarded hot plate apparatus, correlations of intrinsic thermal conductivity with the structural characteristics of the insulators indicated that the proportion of heat loss by convection was lower for the air-laid structures than for the carded structures. This reduction of heat loss by convection was due to high tor tuosity of the air flow path and larger fiber surface area. Each nonwoven insulator was subjected to 10 launderings to evaluate the effect of this action on thermal properties, thickness, air permeability, and weight. The mixed linear density, air-laid structures, hollow fiber insulator, and conventional fibafill decreased markedly in thermal resistance, while the low linear density insulators and the crimped polyester insulator exhibited only small changes as a result of the laundering process.
A Mechanical Model for the Lateral Compression of Woven Fabrics
Authors: De Jong S. , Snaith J.W. , Michie N.A. 
Published: March 2008

A mechanical model for the lateral compression of woven fabrics is derived from Van Wyk's compression law for fiber assemblies. The pressure ( P) and thickness (v) relationship is P = a/( v - v')3. The parameter v' refers to the core of the fabric, which is incompressible over the pressure range 2-5000 gf/cm 2. The parameter a refers to the compressible surface layers and is dependent on the mass of fibers in the surface layers and their orientation. A comparison is made of the results obtained with the KES-F fabric compression tester and the standard fabric thickness tester. The energy of compression is proportional to the cube root of the parameter a. The compressibility of the fabric is proportional to the energy of compression per unit volume of fabric. The changes that occur in the fabric surface layers during a typical fabric finishing process are investigated.
Models of second language competence: a structural equation approach
Authors: Sang F. , Schmitz B. , Vollmer H.J. , Baumert J. , Roeder P.M. 
Published: March 2008

Starting with a critical discussion of the consensus reached concerning the structure of second language competence, the unitary competence hypothesis as advocated especially by Oller (1976) is then confronted with new evidence supporting a multidimensional model of foreign language ability. In order to question the plausibility of the general (unitary) factor hypothesis, its central claim, that of universal validity, is put to the test. This claim implies at least two assumptions: a) the invariance of the general factor, regardless of differences in the populations studied, and b) the invariance of this factor irrespective of the conditions under which language acquisition takes place. By showing divergent structures in subgroups of high and low first language ability, the first assumption would be falsified. By demonstrating specific influences of two teaching styles on different language components, the second assumption could be disproved. The analyses are based on data from a sample of 14 000 seventh grade students and their teachers from 427 secondary schools ('Gymnasien') being highly representative for West Germany and West Berlin. The hypotheses were tested using confirmatory factor analysis (LISREL). The results obtained show the appropriateness of the three factor model proposed (ELEMENTARY, COMPLEX, COMMUNICATIVE), which is theoretically meaningful and best fits the data. Moreover, the expected effects of first language ability grouping and of teaching strategies on the structure of second language competence clearly emerge. In spite of the limitations of the data set analysed, these results can all be interpreted as strong and further evidence against a single factor model (and its educational implications) and in favour of a multiple factor model as outlined above. Finally, didactical consequences of these findings are discussed.
An investigation of a criterion- referenced test using G-theory, and factor and cluster analyses
Authors: Kunnan Antony John 
Published: March 2008

There has been relatively little research on analytical procedures for examin ing the dependability and validity of criterion-referenced tests especially when compared to similar investigations for norm-referenced ESL or EFL tests. This study used three analytical procedures, namely, G-theory, factor and cluster analyses, to investigate the dependability and validity of a criterion-referenced test developed at the University of California, Los Angeles in 1989. Dependability estimates showed that test scores are not equally depend able for all placement groups and are rather undependable for two out of the four placement groups. Factor analysis of test scores for the placement groups showed that though two-factor solutions were the best solutions for the different groups, there were differences in the way the subtests loaded in the different groups, with progressively fewer subtests loading on the second factor as ability increased. This finding led to the extension study with cluster analysis which showed that a number of students might have been differently placed if subtest scores were used to place them.
The role of test-taker feedback in the test development process: test-takers' reactions to a tape-mediated test of proficiency in spoken Japanese
Authors: Brown Annie 
Published: March 2008

This study explores how test-taker reactions in a specific purpose testing context may vary according to characteristics of the test-taker. Such reactions are of interest both theoretically to the researcher and practically to the test developer, who is concerned to ensure that the test is fair and appropriate for all candidates and acceptable to the range of test-takers. The reactions may also be of use in the improvement of test items (as a supplement to item analysis) and test rubrics. The article reports on the use of test-taker feedback in the development of the occupational foreign language test (Japanese), a tape-mediated test of spoken Japanese for the tourism and hospitality industry. Some 53 trial subjects completed a post-test questionnaire, providing reactions to the test as a whole, to task types, and to individual test items. Relationships are investigated between responses and a number of test-taker characteristics, including gender, type of course undertaken (general or specific purpose), amount of study of the language, time spent in Japan and relevant occupa tional experience. Responses are also considered for items and person shown by Rasch IRT analysis as indicating significant misfit. Aspects of the content, construct and face validity of the test are considered in the light of the analysis. The role of feedback in the revision of test items, in the writing of test rubrics and in the development of the test-user handbook is also discussed.
Testing tasks: issues in task design and the group oral
Authors: Fulcher Glenn 
Published: March 2008

This article investigates some of the issues which surround the use of tasks in oral tests, with particular reference to the group discussion. This is done from the perspective of a group of students who were asked to attempt three oral tasks. Questionnaire techniques and retrospective reports were used to collect data from the students. The principle is that test-takers have a great deal to offer to the test researcher in making judgements about the value of the tests which they take (Brown, 1993). The issues surrounding task design and use are complex, and are currently being debated not only in language-testing circles but also in the fields of second language acquisition and discourse analysis. For this reason, this article will refer to discussions in all three areas to shed light on the selection of tasks for use in oral tests. Information from the statistical analysis of tests will also be presented. All views about tests and tasks used in tests, however much some authors might eschew theory or statistical analysis (Underhill, 1987), spring from inherent theoretical positions. These positions make predictions about test scores under particular conditions, and the results of analysis enable the researcher to assess whether a view can be supported by empirical evidence. Finally, the article will look at what is possibly one of the most problematic questions in proficiency testing: the generalizability of a test score given on one task to another task or tasks. It is arguably the case that, if this is not possible, there is no justification for proficiency testing.
An investigation of patterns of discontinuous learning: implications for ESL measurement
Authors: Perkins Kyle , Brutten Sheila R. , Gass Susan M. 
Published: March 2008

Research from cognitive psychology, L2 acquisition and psychometry sug gests that competence/proficiency is multidimensional, and that proficiency does not always develop at the same rate in all its domains. In particular, L2 acquisition research indicates that competence does not always develop in a linear, monotonic pattern at an equal rate in all its component parts owing to restructuring and reorganization. Rehearsal, automatic and controlled pro cessing, creative simplification, task constraints and attention to form have been adduced to explain restructuring and reorganization. Classical test theory and item response theory models are not consonant with findings from cognitive psychology and L2 acquisition, because these models pinpoint individuals on a single continuum of proficiency. The study reported here tested the experimental hypothesis that there would not be a monotonic relationship between increasing competence in different linguistic domains and growth in L2 proficiency. There was general support for the hypothesis. The article concludes with a brief introduction to some assessment models which can accommodate discontinuous patterns of growth. The models examined can be used to describe and model a student's qualitative cognitive state and knowledge structures.
Does thick description lead to smart tests? A data-based approach to rating scale construction
Authors: Fulcher Glenn 
Published: March 2008

Within the fields of applied linguistics and language testing, there has been a recent interest in rating scales, and how rating scales are constructed (Upshur and Turner, 1995). This is not surprising, as there is increasing concern that scores from language tests should be meaningful in applied linguistics terms. However, applied linguistics research and second language acquisition research have done little to provide descriptions of language abilities or performances which can be operationalized by language testers. Many existing descriptors for bands in rating scales are therefore barely tenable as definitions of constructs. This article looks at the definition of fluency in the literature, and proposes a qualitative and quantitative approach which may be used to produce a 'thick' description of language use, which can be used in rating scale construction. A fluency rating scale is described, and its reliability and validity assessed. The arti cle suggests that validity considerations must be addressed in the construction phase of developing rating scales, through the careful consideration of the linguis tic meaning of constructs, rather than merely as a post hoc enterprise.
Long-Term Leaching Scenarios for Cement-Based Waste Forms
Authors: Côté Pierre L. , Bridle Trevor R. 
Published: March 2008

Cement-based waste forms (solidified wastes) are used for the long-term land disposal of industrial hazardous wastes. A cement-based waste form can be prepared by mixing a hydraulic cement and, if needed, a bulking agent with an aqueous waste to cause it to solidify. This article presents eight long-term leaching scenarios based on various properties of waste forms and contaminants as well as different hydraulic regimes and characteristics of groundwater. Each scenario takes the form of a simplified mathematical model used to predict leaching rates for periods of up to 100 years. The analysis demonstrates the importance of chemically fixing the contaminants in the matrix and illustrates the advantages of avoiding situations where groundwater flows through the waste. In situations where advective transport is negligible, leaching rates are limited by pore diffusion and tend to decrease with time.