Evaporated Thin Films of CdS and CdTe: Optimization for Photovoltaic Applications

Thin films of cadmium sulphide and cadmium telluride have been prepared by thermal evaporation under various conditions of deposition. These films have been characterized optically. electrically and for structure determination. The results of these characterizations along with the initial results of all thin film CdS/CdTe solar cells are presented in this paper     

Morphological and palynological assessment of taxonomically problematic genus Paspalum based on light and scanning electron microscopy

Present research work was carried out to clarify the variations among species of genus Paspalum morphologically and palynologically as this genus is taxonomically difficult due to having multiple similar morphologically overlapping characters which make it difficult to identify. Henceforth present research work was carried out to delimit taxa within the same genus by morphological and palynological tools through light microscopy (LM) and scanning electron microscopy (SEM). Both these tools are considered as the most useful taxonomic characters for taxonomically problematic genera. The results showed a lot of variations among morphological characters. In Paspalum dilatatum, the upper glume was ovate whereas in the other two species, the upper glume was elliptic. The upper glume apex found in P. dilatatum and Paspalum scrobiculatum was obtuse whereas in Paspalum distichum, upper glume apex was acute. Glume nerves showed variation in all three species. Paspalum distichum was 3 nerved, P. scrobiculatum was 5–7 nerved, and P. dilatatum was 5–9 nerved. All three species showed variation in lemma nerves. Paspalum scrobiculatum had 3 nerved lemma whereas in P. distichum 3–5 nerved and P. dilatatum 5–9 nerved lemma were present. In polar and equatorial view, pollen grains ranged from 25 (20–30) to 37.5 (30–45) μm. Paspalum distichum appeared to be the smallest in size whereas P. dilatatum was the largest. Exine thickness ranged from 0.75 (0.5–1) to 1.35 (1.2–1.5) μm. The higher value of pollen fertility was found in P. scrobiculatum as 87.69% and the lowest value was in P. distichum as 78.08%. Morphological keys were also given for correct identification.     

Implication of palynological techniques for the authentication of adulterated drugs traded with the same name in different herbal markets of district Lahore,Pakistan

Adulteration in traded medicinal plants is a significant issue nowadays and use of these adulterated medicinal plants can impose harmful impact to end user. However, this problem can be overcome by ensuring the identification of traded medicinal plants which are used in making different herbal medicines. In this regard, palynological markers are considered to be an important taxonomic tool in the identification of original medicinal plant from its adulterant. Hence this study attempted to provide particular reliable palynological markers for distinguishing selected medicinal plants from their adulterants, that is, Cinnamomum verum versus Canella winterana, Cinnamomum tamala versus Cinnamomum obtusifolium, Gymnema sylvestre versus Gymnema lactiferum, Artemisia maritima versus Artemisia absinthium, Achillea millefolium versus Adhatoda vasaka, Sphaeranthus indicus versus Sphaeranthus africanus, Averrhoa carambola versus Butea monosperma, and Morus nigra versus Morus alba. Results demonstrated great variations in multiple palynological characters between original medicinal plant and its adulterant such as in pollen size, shape, colpi length, exine, intine thickness, and fertility. In equatorial view, circular to spheroidal shape of pollen was found in A. millefolium while oblate shape was observed in A. vasaka. Similarly B. monosperma pollen was 34 μm, whereas pollen of its adulterant A. carambola was 21 μm. Moreover, colpi length of A. maritima was 11.8 μm, whereas 4.5 μm in A. absinthium. Hence it can be concluded that palynological characters are commendably helpful in identification of genuine medicinal plant from its adulterant.     

Comparing double-step and penalty-based semirecursive formulations for hydraulically actuated multibody systems in a monolithic approach

The simulation of mechanical systems often requires modeling of systems of other physical nature, such as hydraulics. In such systems, the numerical stiffness introduced by the hydraulics can become a significant aspect to consider in the modeling, as it can negatively effect to the computational efficiency. The hydraulic system can be described by using the lumped fluid theory. In this approach, a pressure can be integrated from a differential equation in which effective bulk modulus is divided by a volume size. This representation can lead to numerical stiffness as a consequence of which time integration of a hydraulically driven system becomes cumbersome. In this regard, the used multibody formulation plays an important role, as there are many different procedures for the constraint enforcement and different sets of coordinates to choose from. This paper introduces the double-step semirecursive approach and compares it with a penalty-based semirecursive approach in case of coupled multibody and hydraulic dynamics within the monolithic framework. To this end, hydraulically actuated four-bar and quick-return mechanisms are analyzed as case studies. The two approaches are compared in terms of the work cycle, energy balance, constraint violation, and numerical efficiency of the mechanisms. It is concluded that the penalty-based semirecursive approach has a number of advantages compared with the double-step semirecursive approach, which is in accordance with the literature.

     

Catalytic co‐pyrolysis of Eichhornia Crassipes biomaѕѕ and polyethylene using waste Fe and CaCO3 catalysts

A wild aquatic plant, Eichhornia Crassipes, and polyethylene have been converted into liquid product thermo‐catalytically and cost effectively through co‐pyrolysis using batch steel pyrolyzer. The Fe and CaCO₃ catalysts were obtained as wastes from various mechanical processes. The catalytic process was compared with non‐catalytic pyrolysis. The effect of various reaction conditions was investigated in order to find out the optimized process conditions. It was found that the favorable reaction conditions were 450 °C temperature and 1‐h reaction time at a heating rate of 1 °C/s and 0.4‐mm biomass particle size. The bio‐oil yield was found to be 34.4% and 26.6% using Fe and CaCO₃ respectively with catalysts particle size of 0.4 mm at the optimized reaction conditions and 5 wt% of biomass. The non‐catalytic and catalytic co‐pyrolysis using Fe as catalyst produced 23.9% and 28.7% oil respectively. Thus the efficiency of processes in terms of bio‐oil production was found in order of: Fe > CaCO₃ > non‐catalytic pyrolysis. The GC/MS analysis of n‐hexane extract of bio‐oil shows that Fe catalyst favors formation of aliphatic hydrocarbons while CaCO₃ and non‐catalytic pyrolysis favors formation of aromatic hydrocarbons. Mostly unsaturated aliphatic hydrocarbons were formed in case of co‐pyrolysis reactions. The calorific value of bio‐oil was also measured in order to find out the fuel properties of the products. Copyright © 2016 John Wiley & Sons, Ltd.