A Transceiver Front-End for Ultra-Wide-Band Applications

An integrated pulse based ultra-wide-band (UWB) transceiver front-end is presented in this paper. The pulse generator produces Gaussian modulated pulses satisfying Federal Communication Commission spectral mask with possibility for binary-phase shift keying modulation. The generated pulses have a bandwidth of 2 GHz from 3.1 to 5.1 GHz. The receiver front-end consists of an UWB low-noise amplifier (LNA). The transmit and receive paths are chosen by a transmit/receive (T/R) switch. The pulse generator, T/R switch and the LNA are integrated on a single chip and fabricated using 0.25-mum SiGe:C BiCMOS technology. The integrated circuit components are designed fully differential. The off-chip antenna and bandpass filter are single ended and connected to the T/R switch through a hybrid coupler     

Use of species-specific antisera to adrenal heat-stable antigens for the identification of raw and cooked meats by agar gel diffusion and counter immunoelectrophoretic techniques

Rabbit antisera to adrenal heat-stable and ethanol-precipitable antigens of buffalo, cattle, sheep, goat and pig were used to develop an agar gel precipitation test and a counter immunoelectrophoretic method for the identification of homologous species in raw, partially heated and boiled meat extracts. Immunoabsorption was necessary to make the primary antisera species specific. The specific antisera can be recommended for identification of the species of origin of meats and their mixtures (5-10% adulteration) in raw, partially heated and cooked states even in the case of closely related species, viz cattle and buffalo, sheep and goat.     

Designing of peptides with immuno-modulatory properties using protein A as a probe

A series of reports from our laboratory have described the multifarious properties of protein A of Staphylococcus aureus Cowan I, apart from its IgG binding affinity. Original reports regarding its anti-tumor, anti-toxic, anti-carcinogenic and immunomodulatory properties published earlier by the authors have implicated some uniqueness of this bacterial protein. It was conceived that such diversified properties must lie in its specific peptide sequences, rendering it to act and behave as a multipotent "Biological Response Modifier" (BRM). The high resolution X-ray structure of protein A-Fc complex has been delineated earlier, and has been the foundation of many protein engineering studies. This structure along with the amino acid sequence data of its four repetitive domains provided us the basis for designing an octapeptide. This octapeptide was synthesized by solid phase peptide synthesis considering it as the probable site through which PA binds IgG. This octapeptide (NH2-Gln-Asn-Ala-Phe-Tyr-Glu-Ile-Leu-COOH) is present in the first helical segment of B-domain of protein A, and also is a part of domain D, A and C. This octapeptide has been shown to bind IgG by the immunoblotting technique. The binding affinity of the octapeptide appears to be significantly higher than that of intact protein A, as was revealed by calculation of Ka (association constant) and Kd (dissociation constant) values. This octapeptide might serve as a good immunoadsorbant for IgG and/or immune complexes.     

Treatment of childhood acute lymphoblastic leukaemia with the BFM regimen

This study was undertaken to further characterize the secretory response of the rat pancreas after reserpine treatment. Rats were given reserpine (1 mg kg-1 day-1 i.p.) or vehicle for 7 days. To distinguish between specific effects of reserpine and those related to secondary malnutrition caused by the drug, the secretory response of a group of pair-fed (PF) animals to reserpine was also investigated. Amylase release from dispersed pancreatic acini, prepared from control (C), PF and reserpine-treated (R) rats were used to evaluate functional secretory capacity. Reserpine and pair-feeding caused reduced responses of pancreatic acini to secretin. The pair-feeding-altered secretin response was greatly improved by increasing extracellular Ca2+ concentration, whereas a slight improvement was noticed in the R group. Reserpine significantly reduced the secretory response to the ionophore A23187 at concentrations above 5 x 10(-7) M in 1.25 mM Ca2+; in 2.5 mM Ca2+, the response to the ionophore was significantly higher in the R group than in C at all ionophore concentrations. Furthermore, at 2 x 10(-7) M ionophore, the secretory response to secretin in the R group became significantly higher than that in the C group but comparable to that of the control+ionophore. In conclusion, reserpine affects the secretory response to secretin as did pre-exposure of pancreatic acini to a high concentration of carbamylcholine. The modified secretory response to the ionophore following reserpine treatment indicates that reserpine may act as a 'Ca2+ entry mechanism' antagonist which may explain the partial reduction in the secretin response.     

Characterization of alumina-alumina/graphite/monel superalloy brazed joints

Active metal brazing of alumina with alumina, graphite and monel 404 superalloy was performed at 910 °C for 5 min using TICUSIL (68.8Ag-26.7Cu-4.5Ti in wt.%) as the braze alloy in vacuum of 5 × 10⁻⁶ mbar. The brazed joints were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, nanohardness and Young's modulus measurements by depth sensitive indentation technique. X-ray diffractrometry showed that the Ti-based compounds were formed at the substrate-filler alloy interfaces of the brazed joints as reaction products. The cross sectional microstructures of the brazed joints were observed by scanning electron microscopy. The energy dispersive X-ray analysis determined the elemental compositions at the selective points of the joint cross section, which supported the X-ray diffraction results. The nanohardness and Young's modulus of the substrate-filler alloy interface showed no abrupt change, which suggests reliable joint performance in service.     

Hydraulic Permeability of Food Tissues

Pressure driven flow can arise in a food process due to various reasons such as rapid internal evaporation in microwave heating of a food. Whether intended or unintended, pressure driven flow can be a very significant mode of transport of water, vapor, and other components. The physics of pressure driven flow cannot be lumped into effective diffusivity type formulation in general. Permeability, a material property that is needed to properly describe this physics of pressure driven flow using mechanistic models and is generally unavailable. For the first time, intrinsic permeability of potato and muscle tissues to water were measured by making water flow through the samples under pressure and measuring the flow rate in a dedicated commercial setup for measuring permeability. Intrinsic permeability values were found to be in the range of 10^?17 – 10^?19 m². Permeability of soft food materials change significantly with pressure, however, electron microscope pictures showed no change in structure in potato tissue.     

LiMgPO4:Tb,B OSL phosphor - CW and LM OSL studies

In the adjoining paper, the authors have proposed LiMgPO₄:Tb,B (LMP) OSL phosphor as a potential alternative to α-Al₂O₃:C for dosimetry applications. This calls for developing an understanding on TL and OSL aspects of this highly sensitive LMP phosphor. CW and LM OSL processes were therefore studied experimentally and kinetic analysis was carried out using theoretical models. Continuous wave (CW) OSL curve for LMP phosphor was found not to follow single decaying exponential implying that the CWOSL curve does not follow first order kinetics. Under pre-readout annealing at 125, 200 and 300 °C for 10 s, the nature of decay profile was unaffected and same holds true for optically bleached CWOSL curves. From linearly modulated (LM) OSL studies, it was found that the shape/geometrical factor μ_g was ∼0.72 ± 0.03 for wide range of doses (up to 12 Gy studied) and peak position “t_m” was also independent of dose. The μ_g was found to be unaffected with pre-readout annealing at 125, 200 and 300 °C for 10 s and optical bleaching, however it was found that peak position “t_m” shifted towards higher side in time with increase of optical bleaching. Dose dependence tests were also carried out for LMOSL curves and it was found that peak position “t_m” was independent of dose, which is typical characteristic of curves following first order kinetics. Hence LM-OSL curve might be mixture of more than one component.Further from CW and LM OSL studies, it was also found that the individual contribution from first, second and third TL peak toward OSL is ∼33%, ∼45% and ∼22%, respectively. Traps beyond 350 °C were found not to contribute towards OSL when stimulated using blue LEDs. In the present paper, the CW and LM OSL processes for LMP phosphor were studied experimentally and their kinetic analysis was carried out.