Role of buffer layer at the p/i interface on the stabilized efficiency of a-Si solar cells

Light induced degradation of single junction and double junction a-Si:H solar cells has been studied. Cells with and without buffer layers at the p/i interfaces have been fabricated. It is found that light induced degradation is faster in the cells with buffer layers. Defect density increases faster and degraded efficiency with respect to the initial efficiency decreases at a higher rate for the cells with buffer layers. Spectral response study for double junction cells shows that collection efficiency decreases for the bottom cell only. So it is found that the absolute stabilized efficiency is highest for a double junction cell with buffer layer at the top cell only.     

Performance of double junction a-Si solar cells by using ZnO:Al films with different electrical and optical properties at the n/metal interface

High-quality ZnO:Al films have been prepared by using RF-magnetron-sputtering method with resistivity ranging from 10⁻¹ to 10⁻⁴ Ω cm and transmittance above 90% in visible region. We have fabricated small area (1 cm²) double junction (a-Si/a-Si) solar cells using ZnO/Al and ZnO/Ag as back contact. The conversion efficiency of double junction a-Si solar cell increases from 9.9% to 10.9% by using ZnO/Al back contact and to 11.4% by using ZnO/Ag as back contact. Effect of variation of thickness of i-layer on performance of the cell has also been studied.     

Effect of processing techniques on the performance of Epoxy/MWCNT nanocomposites

The aim of this study is to investigate the optimum technique to disperse Multi‐Walled Carbon Nanotubes (MWCNTs) in SC‐1 epoxy uniformly and to evaluate the effect of processing technique on the performance of SC‐1 epoxy. To achieve better dispersion, MWCNT was mixed with SC‐1 resin directly or premixed with a solvent and then mixed with SC‐1 resin after evaporating the solvent using sonication, thinky mixing and three‐roll mill methods either in isolation or combination. Flexural tests were performed to evaluate mechanical performances and results exhibit up to 27.13, 13.51, and 21.99% improvement on flexural strength, flexural modulus, and maximum strain, respectively, over neat epoxy with only 0.2 wt % loading. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) indicated improvement in storage modulus, T_g, inflection temperature, and residue content, respectively over neat SC‐1 epoxy. Thermal and mechanical properties at higher loading conditions were seen to either reduce or not significantly improve. This was attributed to high viscosity of nanocomposites as determined by rheological analysis which prevents good dispersion of MWNCTs into epoxy system at 0.4 wt % loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Changes in the localization of MHC class II positive cells in hen ovarian follicles during the processes of follicular growth, postovulatory regression and atresia

The aim of this study was to determine the changes in the population of major histocompatibility complex class II positive (MHC-II(+)) cells in ovarian follicles during the processes of follicular growth, postovulatory regression and follicular atresia in hens. Cryostat sections of ovarian stroma containing cortical follicles, small white follicles, the largest (F(1)) and third largest (F(3)) preovulatory follicles, postovulatory and atretic follicles of laying hens were prepared. The sections were immunostained for MHC-II molecules using mouse anti-chicken MHC-II monoclonal antibody and positive cells were counted using a computer-assisted image analyser under a light microscope. MHC-II(+) cells were localized in the theca layer of normally growing follicles including cortical follicles, small white follicles and F(3) and F(1) preovulatory follicles, whereas they were found in both the theca and granulosa layers in postovulatory and atretic follicles. The frequency of MHC-II(+) cells in the theca layer was significantly increased during follicular growth from cortical follicles to F(3) preovulatory follicles. Although the population of MHC-II(+) cells did not differ between F(3) and F(1) preovulatory follicles, it increased significantly in postovulatory follicles (P < 0.01). The population of MHC-II(+) cells was significantly greater in the theca layer of atretic follicles than in non-atretic follicles (P < 0.01). These results indicate that the antigen-presenting function via MHC-II increases in association with follicular growth. A marked increase in MHC-II(+) cells indicates that these cells may be involved in regression of postovulatory and atretic follicular tissues.     

单层基板涂覆式彩色胆甾型液晶显示

描述了新型超薄彩色胆甾型液晶显示器,该显示器的各个功能层是依次涂覆于一个柔性基板上的。首次采用共享电极驱动器驱动无源矩阵彩色的乳液基的显示器,该显示器是由三层包埋于聚合物基体中的胆甾型微滴层积而成。     

The world photovoltaic scale: an international reference cell calibration program

This paper describes the World Photovoltaic Scale (WPVS) international reference cell calibration program. The WPVS provides a scale for PV performance measurements that has been established through round‐robin calibration of a group of primary monocrystalline Si reference cells and is traceable to Système International (SI) units. Procedures for recalibration of the reference cell group have been devised, along with procedures for admittance and calibration of new reference cells. A reference cell package has been designed that meets the unique needs of the WPVS. It is hoped that the existing WPVS group will eventually be replaced with cells of the new design that have passed a comprehensive acceptance‐test procedure. Copyright © 1999 John Wiley & Sons, Ltd.     

Quality of v-process moulds through the taguchi technique

The global consciousness for quality has motivated designers and manufacturing engineers to be engaged constantly in product and process development. The approach, quality by design, developed by Taguchi has produced a unique and powerful quality improvement discipline that differs from traditional practices. In the present paper, Taguchi's technique has been applied to obtain an optimal setting of V-process parameters. The results indicate that the sand grain fineness number and amplitude of vibration are the control factors. These factors affect both the mean and the variation of the bulk density of the V-process mould. The signal factor, that is the factor that affects only the mean value, is time of vibration. The insignificant factor is the degree of vacuum imposed. The optimum value of bulk density (1–588 gm/cm³) at the optimal setting of these parameters has been obtained and confirmed by further experiments.     

Modeling of the Oxygen Transfer Characteristics of a ‘See‐Saw’ Bioreactor

Animal cell line culture is difficult in the existing conventional bioreactors. A substantial amount of animal cells are destroyed by the impinging fan blades or entrapment inside the bubbles. An endeavor has been made to design and develop a new type of bioreactor suitable for animal cell culture. The bioreactor is named a ‘see‐saw’ bioreactor from its underlying principle of operation. In this paper, the oxygen transfer characteristics of the ‘see‐saw’ bioreactor are modeled and tried to be verified.     

Strategy for promotions and development of renewable technologies in Bangladesh: experience from Grameen Shakti

This paper discusses experiences from the renewable energy program of Grameen Shakti (GS), which is aimed to provide energy to rural areas. GS has already passed 3 years in marketing solar home system in rural Bangladesh. Within this short period, GS gathered a lot of experience in marketing the solar home system. Up to July 1999, GS had sold 1147 solar home systems and the installed capacity was 53.3 kWp. Customers use these systems for various purposes like, lighting houses, shops, offices, watching TV, operating computer and so on. The systems are functioning well. Some of the customers have enhanced income through PV systems by extending working hours and selling power to neighbors. There are various obstacles for expansion of PV program in rural Bangladesh, the main barrier being the high cost of PV module. To make the system affordable, customers need easier financing scheme. GS offers easier financing terms to the customers so that they can afford solar home system.