Development of Technology for Large Scale Production of Titanium Sponge

Intensive investigations on the development of titanium metal production technology had been carried out during 1965-1975 at the Bhabha Atomic Research Centre, Bombay and at the Nuclear Fuel Complex, Hyderabad. The Defence Metallurgical Research Laboratory, Hyderabad has set up a ‘Titanium Sponge Experimental Facility’ with a capacity to produce 100 tonnes of sponge per annum in 2000 kg batches by the Kroll’s process with a view to optimising technology for large scale production.The paper presents an outline of the experimental facility and discusses the various considerations that have gone into the design of equipment, materials of construction, process selection, etc. The facility has gone into operation in March,1985. The results obtained so far are encouraging

Isolation and Characterization of Baculoviruses from Three Major Lepidopteran Pests in the Semi-Arid Tropics of India

Baculoviruses were isolated from three major lepidopteran pests, Helicoverpa armigera, Spodoptera litura and Amsacta albistriga in the semi-arid tropics during natural epizootic conditions at ICRISAT fields, Patancheru, Andhra Pradesh, India. Biological, morphological and biochemical analysis identified these isolates as Nucleopolyhedroviruses (NPVs). Scanning electron microscopy of the occlusion bodies (OBs) purified from diseased larvae revealed polyhedral particles of size approximately 0.5–2.5 lm [Helicoverpa armigera Nucleopolyhedrovirus (HearNPV)], 0.9–2.92 lm [Spodoptera litura Nucleopolyhedrovirus (SpltNPV)] and 1.0–2.0 lm [Amsacta albistriga Nucleopolyhedrovirus (AmalNPV)] in diameter. Transmission electron microscopy of thin sections of OBs of the three isolates revealed up to 5–8 multiple bacilliform shaped particles packaged within a single viral envelope. The dimensions of these particles were 277.7 9 41.6 nm for HearNPV, 285.7 9 34.2 nm for SpltNPV and 228.5 9 22.8 nm for AmalNPV. Each of HearNPV and AmalNPV contained up to 6 nucleocapsids and SpltNPV contained up to 7 nucleocapsids per envelope. The estimated molecular weights of the purified OB (polyhedrin) protein of the three NPVs were 31.29–31.67 kDa. Virus yield (OBs/larva) was 5.18 ± 0.45 9 109 for HearNPV, 5.73 ± 0.17 9 109 for SpltNPV and 7.90 ± 0.54 9 109 for AmalNPV. The LC50 values of various NPVs against 2nd and 3rd instar larvae indicated 2.30 9 104 and 1.5 9 105 OBs/ml for HearNPV, 3.5 9 104 and 2.4 9 105 OBs/ml for SpltNPV and 5.6 9 104 and 3.96 9 105 OBs/ml for AmalNPV. The lethal time required to cause 50% mortality (LT50) for these three species were also defined. This study has shown that the NPVs infecting three major lepidopteran pests in India are multiple NPVs, and they have good potential to use as biocontrol agents against these important pests

Titanium as an Automotive Material

Titanium alloys have made entry into automotive industry and the future trends indicate good prospects of growth for this material. Many modern desingns of high speed and sports car have incorporated substantial quality titanium in their making. The paper reviews the titanium alloys and their processing and the status of titanium technology in the country. A case for promotion of titanium in the automotive sector is also presented

AN ANALYSIS STUDY OF PROTECTION LEVELS AT A LOW LATITUDE INDIAN STATION FOR THE GAGAN

GPS-aided Geo-augmented Navigation (GAGAN) provides an improvement in accuracy and integrity to Global Navigation Satellite System (GNSS) signals for navigation and positioning applications in India. GAGAN system expected to meet Category I Precision Approach (PA) requirements (Horizontal positional accuracy: 7.9 m (95%) and Vertical positional accuracy: 4.3 m (95%)) for aircraft landings. Ionospheric differential corrections must be estimated using GNSS satellite signals since it is rather random and less predictable in low latitude ionospheric regions. Ionospheric irregularities cause changes in amplitude and phase of GPS signal, thus, introducing range errors. The calculation of protection levels is important in the evaluation of accuracy and integrity requirements. In this paper, GNSS data collected at Koneru Lakshmaiah (KL) University, Guntur, India was considered for carrying out the analysis of protection levels for GNSS users. Horizontal and Vertical Protection Levels were calculated and compared with the values measured on quiet and disturbed days. It is evident from the results that as the range error and TEC variations were more predominant during the disturbed days, the protection limits exceeded the permissible range (Vertical protection limit = 50 m and Horizontal protection limit = 40 m). It is observed that there was a significant rise in DOP values indicating the reduction of accuracy and availability

Technology trends in the extractive metallurgy of zirconium, titanium, tantalum and niobium

The reactive and refractory metals zirconium, titanium, tantalum and niobium have been in commercial production and industrial application over the last 30 years and more. With growing experience, there has been progressive improvement in process and equipment designs in the industrial practice. There has also been a continuous drive to develop entirely new processes, and to diversify the applications of these metals. The paper reviews the present status and the emerging trends, and places the Indian work in the global perspective

Structural perturbation and enhancement of the chaperone-like activity of α-crystallin by arginine hydrochloride

Structural perturbation of α-crystallin is shown to enhance its molecular chaperone-like activity in preventing aggregation of target proteins. We demonstrate that arginine, a biologically compatible molecule that is known to bind to the peptide backbone and negatively charged side-chains, increases the chaperone-like activity of calf eye lens α-crystallin as well as recombinant human αA- and αB-crystallins. Arginine-induced increase in the chaperone activity is more pronounced for αB-crystallin than for αA-crystallin. Other guanidinium compounds such as aminoguanidine hydrochloride and guanidine hydrochloride also show a similar effect, but to different extents. A point mutation, R120G, in αB-crystallin that is associated with desmin-related myopathy, results in a significant loss of chaperone-like activity. Arginine restores the activity of mutant protein to a considerable extent. We have investigated the effect of arginine on the structural changes of α-crystallin by circular dichroism, fluorescence, and glycerol gradient sedimentation. Far-UV CD spectra show no significant changes in secondary structure, whereas near-UV CD spectra show subtle changes in the presence of arginine. Glycerol gradient sedimentation shows a significant decrease in the size of α-crystallin oligomer in the presence of arginine. Increased exposure of hydrophobic surfaces of α-crystallin, as monitored by pyrene-solubilization and ANS-fluorescence, is observed in the presence of arginine. These results show that arginine brings about subtle changes in the tertiary structure and significant changes in the quaternary structure of α-crystallin and enhances its chaperone-like activity significantly. This study should prove useful in designing strategies to improve chaperone function for therapeutic applications

Arginine hydrochloride enhances the dynamics of subunit assembly and the chaperone-like activity of α-crystallin

Purpose: α-Crystallin, a major eye lens protein, bears homology with small heat shock proteins (sHsps) and exhibits molecular chaperone-like activity. Structural perturbation by temperature or low concentrations of denaturants leads to enhancement of its chaperone-like activity. We have earlier demonstrated similar enhancement of chaperone-like activity using biologically compatible solutes such as arginine hydrochloride and aminoguanidine. The purpose of the present study is to get an insight into the mechanism of the arginine induced enhancement of chaperone-like activity of α-crystallin. Methods: The effect of arginine hydrochloride on the chaperone-like activity of α-crystallin at 25 °C was studied using DTT induced aggregation of insulin as a model system. Changes in the accessibility of the thiol group near the end of the α-crystallin domain in the absence and the presence of arginine hydrochloride were studied using dithiobisnitrobenzoic acid. Fluorescence resonance energy transfer studies were performed to investigate changes in the dynamics of the subunit assembly. Urea induced denaturation studies of α-crystallin were carried out to investigate structural destabilization of α-crystallin, if any, in the presence of arginine hydrochloride. Results: Arginine hydrochloride increases the chaperone-like activity of α-crystallin several fold towards DTT induced aggregation of insulin at room temperature. Our study shows that both the extent and the rate of accessibility of the thiol group are increased in the presence of arginine. Fluorescence resonance energy transfer experiments show that arginine hydrochloride significantly increases the subunit exchange between the oligomers of α -crystallin. Arginine induced structural perturbation and loosening of subunit assembly of α-crystallin leads to overall destabilization of the protein as reflected by the urea denaturation study. Conclusions: Arginine perturbs the tertiary and quaternary structure of α-crystallin and enhances the dynamics of the subunit assembly leading to enhanced chaperone-like activity. Thus, in addition to size, surface hydrophobicity, and charge distribution, the dynamics of the subunit assembly appears to be one of the critical factors that can modulate the chaperone activity

Prediction and Analysis of Rain Attenuation using ARIMA Model at Low Latitude Tropical Station

ABSTRACT: Rain attenuation is one of the important impairments that affects RF signal at Ku and Ka band frequencies. The forecasting of the rainfall and rain attenuation plays a vital role in the fields of communications, agriculture, military services, etc. The paper shows the results of experimentally measured rain attenuation of earthspace link in Kondapalli operating at 11.07 GHz. Auto-Regressive Integrated Moving Average (ARIMA) model is used to predict and generate the time series values for rain attenuation over a long period. The predicted values obtained using ARIMA model is compared with measured values of rain attenuation for different set of parameters of the model and analysis is done in terms of prediction error which could be used for the validation of the method. Keywords: Rain attenuation, ARIMA model, ITU-R model, Time series, ccdf. I.INTRODUCTION Satellite communication systems operating at and above Ku band frequencies must overcome the problem of propagation impairments which includes fading due to rain, clouds, snow, gases, and amplitude scintillations, for obtaining the required performance. Among all impairments, rain is the predominant factor that affects the signal most and the mechanism involved is absorption and scattering of the signal energy. The estimation of attenuation on the slant path to a satellite is essential to the process of establishing a margin in the link budget that ensures the required availability of the link is met Number of models have been proposed and developed for prediction and generation of time series data of rain attenuation based on auto-regressive moving average processes A. ITU-R Rain Attenuation Prediction Model Rain attenuation is the significant propagation impairment at Ku and Ka band frequencies. In ITU-R rain attenuation prediction model, the rain intensity at 0.01% probability level is the rain related input to the model. The model has been derived on the basis of the log-normal distribution where both point rain intensity and path attenuation distributions conform to the log-normal distribution. The model is applicable across the frequency range 4 to 35 GHz and percentage probability range 0.001% to 10%. The input parameters to this model are: point rainfall rate for 0.01% of an average year (in mm/hr) with 1-min integration time, altitude of the location above mean sea level (in Km), elevation angle of the receiver (in degrees)

Heat stress-induced localization of small heat shock proteins in mouse myoblasts: intranuclear lamin A/C speckles as target for αB-crystallin and Hsp25

We examined the effect of heat stress on localization of two sHsps, αB-crystallin and Hsp25, and of Hsc70, a member of a different class of heat shock proteins (Hsps), in both undifferentiated and differentiated mouse C2C12 cells. Under normal conditions, αB-crystallin and Hsp25 are found in the cytoplasm; only αB-crystallin is also found in the nucleus, distributed in a speckled pattern. Hsc70 is found to be homogeneously distributed throughout the cell. On heat stress, all these proteins translocate almost entirely into the nucleus and upon recovery relocate to the cytoplasm. Dual staining experiments using C2C12 myoblasts show that αB-crystallin and Hsp25, but not Hsc70, colocalize with the intranuclear lamin A/C and the splicing factor SC-35, suggesting interactions of sHsps and intranuclear lamin A/C. Interestingly, none of these proteins are found in the myotube nuclei. Upon heat stress, only Hsc70 translocates into the myotube nuclei. This differential entry of αB-crystallin and Hsp25 into the nuclei of myoblasts and myotubes upon heat stress may have functional role in the development and/or in the maintenance of muscle cells. Our study therefore suggests that these sHsps may be a part of the intranuclear lamin A/C network or stabilizing this specific network