Prolactin gene polymorphism in Nili‐Ravi buffaloes in relation to Sahiwal and Achai Cattle

In this study, prolactin gene polymorphism was investigated in Nili‐ Ravi buffaloes, Sahiwal and Achai cattle breeds, 100 per group, using polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) technique. Only genotype GG was observed in the case of Nili‐Ravi buffaloes. In Sahiwal and Achai cattle, three genotypes were found, AA, AG and GG: the frequency of these genotypes were 72%, 18% and 10% in Sahiwal cattle and 44%, 34% and 22% in Achai cattle, respectively. The frequency of genotype AA was found to be higher in both cattle breeds. Results of chi‐square test at P < 0.05 revealed that animals of Achai cattle were in Hardy–Weinberg equilibrium, whereas Sahiwal cattle were found to be deviating.     

质子束轰击下MWCNTs无定形结构的转变

在室温下用70keV质子束多壁碳纳米管(MWCNTs),研究了多壁碳纳米管从石墨结构向无定形结构的转变过程。轰击后,MWCNTs外围的石墨结构变成均匀的无定形结构包覆着内部的石墨结构。增大照射量,这种无定形化的过程继续向MWCNTs内层推进,直至形成一个中空的无定形纳米线结构。质子束轰击引入的MWCNTs的结构转变,是从外层向内层逐步推进的石墨结构向无定形结构的转变过程。本文对这种结构演化的机理进行了讨论。     

Growth and characterization of V2O5 thin film on conductive electrode

Vanadium pentoxide V₂O₅ thin films were grown at room temperature on ITO coated glass substrates by electrochemical deposition. The resulting films were annealed at 300, 400 and 500°C for 1 h in ambient environment. The effect of heat treatment on the films properties such as surface morphology, crystal structure, optical absorption and photoluminescence were investigated. The x‐ray diffraction study showed that the films are well crystallized with temperatures. Strong reflection from plane (400) indicated the film's preferred growth orientation. The V₂O₅ films are found to be highly transparent across the visible spectrum and the measured photoluminescence quenching suggested the film's potential application in OPV device fabrication.     

Optical absorption of ion irradiated multi-walled carbon nanotube sheets in the visible to terahertz ranges

ecreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.     

Improvement in tensile properties of PVC–montmorillonite nanocomposites through controlled uniaxial stretching

In this paper we present the results exhibiting an improvement in the tensile properties of polyvinyl chloride (PVC)?Cmontmorillonite nanocomposites through uniaxial stretching. The clay was dispersed in PVC matrix with the help of dodecylamine. PVC?Cmontmorillonite nanocomposites films containing varying amounts of clay (0?C5%) were produced through solution elution technique. The films were stretched uniaxially at a constant temperature of 80?°C in three different steps using controlled loads. X-ray diffraction and stress?Cstrain curves were obtained for both unstretched and stretched films in order to determine the improvement in various properties. The controlled uniaxial stretching of films close to the softening temperature of PVC has resulted in enhancement in the degree of crystallinity in the nanocomposites. This improvement in the structural order has also imparted increase in tensile strength and Young??s modulus of the nanocomposite films.     

Strength, Structure, and Fracture Properties of Ceramic Fibers Produced from Polymeric Precursors: I, Base-Line Studies

Classical brittle failure has been observed for ceramic fibers produced by pyrolysis from three different polymer precursors. Characterization by SEM fractography methods has shown typical flaw-mirror-mist-hackle morphology and such study has provided observations for understanding the fracture mechanisms. The gage length dependence of tensile strength combined with the fractography study showed the flaw-controlled failure mechanism of all the ceramic fibers. Systematic failure types have been identified for specific strength ranges. Complementary study of the microstructure and chemical structure by TEM, X-ray diffraction, and electron spectroscopy for chemical analysis (ESCA) has shown the nature of the bulk ceramic to be predominantly random and glassy even in the case of a fiber with microcrystalline β-SiC. Fracture mechanics calculations have shown the fibers all behave as glasses.     

Remote-sensing applications in Pakistan: current status and future programmes

Abstract

This paper gives a summary of current activities and future programmes of the Remote Sensing Applications Centre (RESACENT) of the Pakistan Space and Upper Atmosphere Research Commission, Karachi, Pakistan.