Archives-December  

Single crystals of pure and Glycine-doped Zinc Thiourea Chloride (ZTC) were grown by slow evaporation technique. 1 molar percent of Glycine was added in saturated ZTC solution. The chemical composition of the crystals were determined by Fourier transform infrared (FTIR) analysis. The unit cell parameters and crystal structure were determined by single crystal X-ray diffraction. The UV-visible absorption spectra of pure and Glycine-doped ZTC showed excellent transmittance from 300 nm to 1100 nm. The thermal stability of the grown crystals was studied by thermo-gravimetric analysis (TGA). The second-harmonic generation efficiencies were studied by Kurtz and Perry powder SHG test and observed an enhancement in the SHG efficiency of Glycine-doped ZTC. Micro hardness study was also carried out on the samples to study the mechanical stability of the grown crystals.

ABSTRACT A series of anthracene-based microporous polymers (AMPs) bridged by imide links were successfully prepared by conventional nucleophilic substitution reaction between several 9,10-dihydro-9,10-ethanoanthracenes and cheaper 2,3,5,6-tetrachlorophalonitrile (instead of fluoro-monomer)1. AMPs display a BET surface area in the range of 811-988 m2 g–1, and reversibly adsorb 1.59 wt. % H2 at 1.09 bar/77 K. The enhanced microporosity, in comparison to other organic microporous polymers prepared from (5,5’,6,6’-tetrahydroxy-3,3,3’,3’-tetramethylspirobisindane)2 originates from the macromolecular shape of framework, as dictated by the anthracene units, which helps to reduce intermolecular contact between the extended planar struts of the rigid framework. The impressive hydrogen adsorption capture of these materials verified by Horvath?Kawazoe (HK) and NLDFT analyses of low-pressure nitrogen adsorption data.

In this study, histological examination of the testicles and cellular tissue changes of sperm cells in the spermatogenesis phase of zebrafish are aimed. In this respect; the microscopic structure of the testicles, the position and form of the cells belonging to spermatogenic string, tissue-generating structural cells, and these organisms are examined with the light microscope. All the phases of spermatogenesis are classified as spermatocytogenesis, meiosis and spermiogenesis taking all the phases and histological development of the cells into consideration. All the cells belonging to these phases are seen in separate groups in seminiferous tubules. It is found out that there are somatic cells around spermagony. And spermatogenic cells return into spermatogenic string cells respectively (primer spermatocyte, secondary spermatocyte, spermatide and sperm organisms) by meiosis.

The aim of this paper is to investigate the linkage between macroeconomic variables (inflation rate, exchange rate and interest rate) on stock market returns in Pakistan. We used the Pakistan Karachi stock exchange 100 index as a proxy to represent the stock market returns and the interest rate, inflation rate, and exchange rate were used as the macroeconomic variables. Secondary data was collected from the period of January 2007 to December 2012. A Multiple Linear Regression was performed for the purpose of data analysis. The study showed that there is weak connection between macroeconomic variables and stock market returns. The research validates the findings of earlier studies as well as conclusions and recommendations are discussed.

This paper focuses on anti-reflective coatings on monocrystalline silicon solar cells and the impact of thickness and refractive index on reflectivity. The reference wavelength of silicon is 700nm, with its optimum refractive index (n = 3.7838) and a surface reflectivity of 33%. The calculations were based on values of layer thickness and refractive indices that meet the chosen phase and amplitude conditions, namely (HfO2), (MgF2); (SiOxNy), (SiOx), (Si3N4) and (SiNx:H). Numerical simulations have shown that low reflectivities at the surface of the single-layer coated planar cell can be obtained (3% with Si3N4) and (2% with HfO2). Multilayers such as MgF2/SiNx:H/Si, give a very low reflectivity of around 1%.

Adders are the most vital part of any digital system. Providing an efficient adder design which satisfies the tradeoff between speed and space aides in increasing the performance of the system. parallel prefix adders are the ones widely used in digital design. This is primarily because of the flexibility in designing the adders. Brent kung adder is low power adder, as it uses minimum circuitry and also decrease the speed and memory to obtain the result. The 16-bit design is extended to 32-bit, implemented in the physical level.

In order to improve the English teaching effect, we adopt the information system as the assistance with the English teaching. By the online function and automatic management with the system software, teachers and students got more communication and achieved more effective results, especially on spoken English. The practice implies that it is feasible and effective to apply the information system to the English teaching.

Responders who search and rescue people in collapsed buildings and structures face individual and organizational challenges. These challenges are surmountable if responders and their institutions tactically endeavor to address them so that more lives are saved. This study sought to determine strategic options for the improvement of response during urban search and rescue. Findings revealed that many responders and organizations lacked code of conduct for responders and were financially and materially deficient during deployment and therefore relied on partnership and collaborations from other first line response organizations to be able to effectively carryout their work.

Employee empowerment seeks to increase the employees’ responsibility, build their morale and improve the quality of their work life by creating a working environment where an employee is allowed to make his own decisions or participate in the decisions of the management in specific work-related situations. Ideally, when an employee feels valued in an organization, he will be more productive, loyal and confident. The main purpose of this study was to establish the influence of employee empowerment on primary school teachers’ performance in Kakamega Central District., Kenya. The study used descriptive and correlation survey design to collect data from 164 teachers through questionnaires and document analysis. Data was analysed using frequencies, percentages and Pearson’s Product moment correlation coefficient test. The study concluded that the autonomy the teachers’ had in their work execution and the impact of their duties had the greatest influence on teachers’ performance. Competence, manifested as training, knowledge and skills they possessed had a minimal effect on teachers’ performance. The study recommends that employees should be encouraged to value their work and be allowed to participate in decision making especially on issues related to task accomplishment in a bid to enhance their performance.

Friction Stir Welding, a relatively new welding process, was developed in 1991 at The Welding Institute near Cambridge, England. In this process parts are mated together, rigidly fixtured, and joined in solid-state by forcing a rotating tool into the joint, and traversing that tool along the joint. This process creates weldments with properties comparable to the base metal and in most cases superior to traditional fusion welding techniques. During the Friction Stir Welding (FSW) process, the forging forces under the tool plastically deform the material, “stirring” the material around the tool pin and against the tool shoulder, thus joining the mated parts together. This process induces large shear forces in the plastically deforming material, raising the temperature of the material to approximately 80% of the melting temperature. The FSW process parameters such as tool rotational speed, welding speed, axial force, etc. play a major role in deciding the weld quality. In present investigation, the effect of processing parameters on mechanical properties of AA6082-O joints produced by friction stir welding was analyzed. Different welded specimens were produced by varying rotating speeds of the tool as 900 & 1200 rpm and by varying welding speeds as 50 & 63 mm/min. The FSW joints mechanical properties of the material such as yield strength, tensile strength and percentage of elongation were evaluated by means of tensile tests.