REPRODUCTIVE POTENTIAL OF MALE RATS FED DIETARY ETHYLENE DIBROMIDE

Ethylene dibromide (EDB), a grain fumigant, has been assessed for its toxic effects when fed to growing albino rats at 50, 100, 250 and 500 ppm in the diet for 90 days. Weekly body weight gain showed no effect on growth. Organ weights were normal and no histopathological lesions were observed in the liver, kidney, lungs, brain, spleen, adrenal gland, and the testis. Activities of the serum enzymes, viz., GOT, GPT, LDH and alkaline phosphatase were not affected. EDB fed male rats when mated with normal female rats showed no impairment in their reproductive performance.     

Joint experiments programme in remote sensing of marine fish resources

A joint experiments programme was undertaken between three government agencies to pool their resources and expertise to develop techniques for ocean-colour sensing. During October, November and December 1981 a remote-sensing experiment was carried out using vessel-based observations and aircraft underflights synchronous to NIMBUS-7 overpasses in coastal waters off Cochin. The area is well known for the abundance of surface schools of oil sardine (Sardinella hngiceps Val) and mackerel (Rastrelliger kanagurta). An aircraft sensor (Ocean Colour Radiometer) with spectral channels similar to that of the Coastal Zone Colour Scanner (CZCS) on board the NIMBUS-7 satellite was flown to collect data at different altitudes to examine the aspects of atmospheric correction and developing a pigment algorithm. From the analysis of the data it was found that (i) vessel-based measurement of upwelling/downwelling irradiance and the derivation of the spectral diffuse attenuation coefficient and reflectance factor is useful in understanding the optical properties of ocean water, (ii) upwelled radiance data derived from the aircraft sensor could be suitably used in the understanding of atmospheric effects and in developing a pigment algorithm and (iii) a non-linear relationship is observed between fish catch and pigment concentration.     

冲击角度与旋转速度对铝冲蚀行为的影响

将工业纯铝暴露在一定浓度的泥浆中,样品以不同的角度固定,并在不同速度下旋转,通过质量损失来测量样品的磨损率。结果表明,当冲击角度小于90°时,样品的磨损率随冲击角度的增加而增加。与传统的认识不同,铝的最大磨损率出现在冲击角为90°,而不是出现在冲击角45°。旋转速度的增加将导致磨损率呈指数增加。这一结果与磨损表面的金相分析一致。     

Large Shear Studs for Composite Action in Steel Bridge Girders

Shear studs used in composite steel bridge construction are typically 19.1 mm (? in.) or 22.2 mm (? in.) in diameter. This paper presents the development and implementation of the 31.8 mm (1??in.) stud diameter. Because the 31.8 mm (1??in.) stud has about twice the strength and a higher fatigue capacity than the 22.2 mm (? in.) stud, fewer studs are required along the length of the steel girder. This would increase bridge construction speed and future deck replacement, and reduce the possibility of damage to the studs and girder top flange during deck removal. Studs also can be placed in one row only, over the web centerline, freeing up most of the top flange width and improving safety conditions for field workers. This paper provides information on the development, welding, quality control, and testing of the 31.8 mm (1??in.) stud. Information on the first bridge built in the state of Nebraska with the 31.8 mm (1??in.) studs is provided.     

Reduced erbium-doped ceria nanoparticles: one nano-host applicable for simultaneous optical down- and up-conversions

This paper introduces a new synthesis procedure to form erbium-doped ceria nanoparticles (EDC NPs) that can act as an optical medium for both up-conversion and down-conversion in the same time. This synthesis process results qualitatively in a high concentration of Ce³⁺ ions required to obtain high fluorescence efficiency in the down-conversion process. Simultaneously, the synthesized nanoparticles contain the molecular energy levels of erbium that are required for up-conversion. Therefore, the synthesized EDC NPs can emit visible light when excited with either UV or IR photons. This opens new opportunities for applications where emission of light via both up- and down-conversions from a single nanomaterial is desired such as solar cells and bio-imaging.     

Sodar observation of elevated layers around Calcutta

Abstract

Sodar (sound radar) echograms recorded at the Indian Statistical Institute, Calcutta, often exhibit stratified or elevated layers over the ground-based inversion. These have been noticed often after the occurrences of thunderstorms and rain. These layers may be single or multiple, continuous or intermittent and are associated with some perturbations even as gravity wavelike structures. All these features of the lower atmospheric structures over this coastal station, as detected by a sound radar, are discussed in this paper.