Evaluation of a university website’s usability for visually impaired students

Today websites are the tools most commonly used to access information. People with disabilities face difficulties accessing or using information, and the importance of website usability in their lives needs to be recognized. Visually impaired students need to be able to use university websites that inform them about the opportunities and events taking place on campus. This study aims to evaluate the usability of a university website by visually impaired students. In this research, six visually impaired students were interviewed. The assistive technologies they use, as well as the various web pages they wished to use unaided were identified. Following data collection, usability tests were conducted and satisfaction surveys were completed. The usability test was done with five visually impaired students. They were asked to think aloud while performing 11 tasks involving their university’s web pages, including the main page and the pages of student affairs, library and departments and then to accomplish these tasks. In this test, five tasks were not successfully completed by all students. According to the test results, finding final exam dates on the academic calendar posed major difficulties, and accessing the course schedule web page was the task that required the most time. The test results indicated the need for a search engine on each page, a text version for all pages, rearrangement of the web link sequences with tabs and more information about visuals. Suggestions related to the visually impaired students’ needs were offered.     

Six Sigma experience as a stochastic process

This study empirically investigates the states of Six Sigma from a stochastic point of view. By the means of an advanced survey, 97 respondents are asked to rate the effect of Six Sigma on different performance categories, the cost of implementing Six Sigma, the level of enthusiasm and expectations from Six Sigma over 20 years. The autocorrelation and cross-correlation functions of these processes are analyzed to investigate the stages of Six Sigma. Consequently, new concepts namely steady state of Six Sigma and Six Sigma experience functions are introduced which shed light on the life cycle of Six Sigma within the companies.     

An electron microprobe analysis of solute segregation near grain boundaries in an Al-Zn-Mg alloy

The concentration of zinc and magnesium across grain boundaries was measured by means of an electron probe microanalyzer for an Ag-Zn-Mg alloy after different quenching (brine, water, oil, and air) and aging heat treatments (room temperature, 165°, and 200°C). Significant solute segregation was detected in quenched specimens and also in specimens that were aged at room temperature. While no solute enrichment was measured in specimens that were aged at elevated temperatures, solute depletion was observed in a considerable proportion of the examined boundaries. It was concluded that solute segregation to grain boundaries occurred during quenching and was relieved during aging. C. R. SHASTRY, Formerly Graduate Research Assistant at Rens-selaer Polytechnic Institute, Troy, N. Y.     

A study of grain boundary precipitate-free zone formation in an Al−Zn−Mg alloy

The effect of quench rate and boundary type on the width of precipitate-free zones in an Al-6.86 wt pct Zn-2.35 wt pct Mg alloy that was aged at two different temperatures was studied by transmission electron microscopy. The width of the precipitate-free zones increased with decreasing quench rate, but by a considerably smaller extent than that predicted from calculations using previous models based upon quenched vacancy profiles. The simple tilt-type boundaries were associated, in general, with narrower precipitate-free zones than those occurring at complex-type boundaries. The width of precipitate-free zones was also observed to decrease with increasing precipitate coverage in the boundary. A mechanism of precipitate-free zone formation based on the modification of the as-quenched vacancy profile by the vacancies generated due to grain boundary precipitation was proposed to explain the observed results. C. R. SHASTRY, formerly Graduate Student, Materials Division, Rensselaer Polytechnic Institute, Troy. N. Y.     

Kinetic and equilibrium studies in removing lead ions from aqueous solutions by natural sepiolite

The capacity of sepiolite for the removal of lead ions from aqueous solution was investigated under different experimental conditions. The Langmuir and Freundlich equations, which are in common use for describing sorption equilibrium for wastewater-treatment applications, were applied to data. The constants and correlation coefficients of these isotherm models for the present system at different conditions such as pH, temperature and particle size were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model and the maximum sorption capacity was found to be 93.4 mg/g for the optimal experimental condition. The thermodynamic parameters (DeltaG(o), DeltaH(o) and DeltaS(o)) for lead sorption on the sepiolite were also determined from the temperature dependence. The influences of specific parameters such as the agitation speed, particle size and initial concentration for the kinetic studies were also examined. The sorption kinetics were tested for first order reversible, pseudo-first order and pseudo-second order reaction and the rate constants of kinetic models were calculated. The best correlation coefficients were obtained using the pseudo-second order kinetic model, indicating that lead uptake process followed the pseudo-second order rate expression.     

Electrical Discharge Machining of Ti6Al4V in Hydroxyapatite Powder Mixed Dielectric Liquid

Hydroxyapatite (HA) powder suspension in deionized water was used as a dielectric liquid during electrical discharge machining (EDM) of Ti6Al4V work material. The machined surfaces were evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy, and optical microscopy. The powder particles in the dielectric liquid extensively migrated and formed an HA-rich layer on the work material surface under specific machining conditions. The result was attributed to the generation of secondary discharges due to altered discharge conditions. The particles divided the primary discharge channel into several secondary ones. When the main discharge channel subdivided into several sub-discharges with comparable energy densities, the particles in the discharge region got stuck among them. Then, they moved toward the melted cavities and penetrated the surface at the end of the discharge duration. The results suggest the process as a practical alternative for producing biocompatible interfaces or coatings for medical applications.     

Determination of alkaloids and phenolic compounds in black tea processed by two different methods in different plucking seasons

The effects of two different rolling methods and three tea plucking seasons on alkaloids and phenolics, mainly flavan‐3‐ols and theaflavins, in black tea were studied using an improved high‐performance liquid chromatographic method. Better separation of all tea compounds analyzed—the most important factor for their identification and quantitation—was achieved only with long elution gradients, which overcame the limitations of previously reported methods. Precision of the assay method was very high since intra‐day and inter‐day variations were within 0.76% and 1.66%, respectively. All analytes exhibited good linearity over the range evaluated with a correlation coefficient of 0.9987–1.000. Among the four solvents evaluated, 80% methanol was the most solvent for extracting individual tea compounds. The extraction method applied exhibited good repeatability (CV: 0.39–3.29%). The content of tea compounds analyzed varied with processing method and plucking season. Teas processed using the Cay‐Kur method contained higher levels of identified phenolic compounds than orthodox teas, but their alkaloid content was similar to each other. The most abundant alkaloid in teas was caffeine, ranging from 17.84 mg g^?1 dry weight in September plucking to 23.79 mg g^?1 dry weight in May plucking. With respect to phenolic compounds, theaflavins were at the highest level, 14.27 mg g^?1 dry weight, in Cay‐Kur tea processed in May. Copyright © 2007 Society of Chemical Industry     

Effects of prolonged heating on antioxidant activity and colour of honey

The kinetics of changes in total antioxidant activity as assessed by DPPH radical and brown pigment formation (BPF) in honey heated at different temperatures (50, 60 and 70 °C) for up to 12 days were studied. Antioxidant activity and BPF increased with treatment temperature and time. BPF increased following zero-order kinetics with the activation energy value of 122 kJ/mol⁻¹ at 50–70 °C. However, antioxidant activity variation showed different trends according to heating temperatures following second-order, first-order and zero-order kinetics at 50, 60 and 70 °C, respectively. Heating of honey at 70 °C was found to be more effective than 50 and 60 °C for both two parameters. The results demonstrated that antioxidant activity was correlated with increased browning of the samples.