Showing papers by "Techno India published in 2002"

Variations in angiotensin-converting enzyme gene insertion/deletion polymorphism in Indian populations of different ethnic origins.

Abstract: The pattern of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in the Indian population is poorly known. In order to determine the status of the polymorphism, young unrelated male army recruits were screened. The population had cultural and linguistic differences and lived in an environment that varied significantly from one region to another. Analysis of the genotype, showed higher frequency of the insertion allele in four of the five groups i.e. I allele frequency was significantly higher (P< 005) in Dogras, Assamese and Kumaonese. The deletion allele frequency was comparatively higher in the fifth group that belonged to Punjab. A correlation was observed between the genotype and enzyme activity. Involvement of a single D allele in the genotype enhanced the activity up to 37.56 ± 313%. The results suggested ethnic heterogeneity with a significant gene cline with higher insertion allele frequency. Such population-based data on various polymorphisms can ultimately be exploited in pharmacogenomics.

Synthesis and characterization of liquid crystalline polymers containing aromatic ester mesogen and a nonmesogenic ferrocene unit in the spacer

Abstract: A new series of liquid crystalline polymers containing aromatic triad ester mesogen and 1,1′-disubstituted ferrocene as a nonmesogenic unit along with polymethylene spacer was synthesized. The polymer was synthesized by a room temperature polycondensation reaction between bis(4-chloroformyl phenyloxy alkyl ferrocene dicarboxylate) and quinol. The alkyl groups have been varied by an even number of methylene groups with a range from two to ten groups. All the polymers were found to possess liquid crystalline properties. The identification of the mesophase is more transparent with an increase in the spacer. The thermal characteristics were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the thermal stability of the polymers was decreased with increasing spacer length. The Tg, Tm, and Ti of the polymers decreased with increasing methylene groups. The incorporation of the ferrocene moiety also has a considerable effect on the glass transition temperature. The char yield of the polymer decreases with an increasing methylene chain length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3494–3501, 2002

Flow behavior characteristics of ice cream mix made with buffalo milk and various stabilizers.

Abstract: Ice cream made with buffalo milk, using optimum levels of various stabilizers of plant origin, was evaluated for its flow behavior characteristics, with the objective of producing an acceptable quality product. The minimum variation in the viscosity of mix was observed at three rates of shear (348.88, 523.33 and 1046.66 S(-1)) for all ice cream mixes. The flow behavior index (n) of all the mixes having optimum levels of various stabilizers was observed to be less than 1; indicating their pseudoplastic nature. Consistency coefficient (m) of sodium alginate was found to be 1.19; highest among all the stabilizers, followed by gelatin (1.17), karaya (1.08), guar gum (0.75), acacia gum (0.70), ghatti gum (0.36), and the control (0.29). The consistency coefficient (m) signifies the apparent viscosity of the pseudoplastic fluid. The viscosity of the mixes having various stabilizers (optimum levels) was found to be in descending order: Sodium alginate, gelatin, karaya, guar gum, acacia, ghatti and control.

Polarized fluorescence spectroscopy of human tissues

Abstract: We report the results of a study carried out to investigate the effect of blood absorption on polarized and unpolarized fluorescence from resected tissue samples and tissue phantoms. The signatures of blood absorption were found to be significantly smaller in polarized fluorescence than in unpolarized fluorescence spectra. The reduced effect of blood absorption on polarized fluorescence also leads to reduced site-to-site variability in polarized fluorescence intensity and line shape compared with unpolarized fluorescence.

Fluorescence depolarization in a scattering medium: Effect of size parameter of a scatterer

Abstract: For a monodisperse scattering medium, we investigate the dependence on scatterer size parameter for the change in anisotropy of fluorescence due to single scattering at excitation or emission wavelength. The value for the ratio of the anisotropy of fluorescence after one scattering at excitation or emission wavelength to the initial value was observed to increase with increasing value of scatterer size parameter. The effect of multiple scattering on anisotropy of fluorescence from fluorophores embedded in a scattering medium was incorporated using a photon migration model. The model was validated by experiments carried out on samples with known concentration of polystyrene microspheres as scatterers and riboflavins or reduced form of nicotinamide adenine dinucleotide as fluorophores.

Diffuse Reflectance Studies of Edible Fats

Abstract: Light scattering properties of ghee (a form of clarified butter) and vanaspati (partially hydrogenated vegetable oil) have been investigated in order to explore the use of optical techniques for detection of adulteration of vanaspati in ghee. Significant differences in the diffuse reflectance spectra of ghee and vanaspati were observed. The estimates for the reduced scattering coefficient (μs′) and the absorption coefficient (μa) for ghee and vanaspati were also obtained from integrating sphere measurements. These suggest that the differences in the diffuse reflectance spectra of ghee and vanaspati are primarily due to the differences in their absorption characteristics in the spectral range of 400 to 550 nm. Further, the results obtained show that the ratio of diffuse reflectance at 460 nm to that at 410 nm could be used to detect adulteration of vanaspati in ghee.

Polarization-gated optical imaging: effect of size parameter of scatterer

Abstract: A theoretical treatment based on electromagnetic theory has been developed for the dependence of depolarization of linearly and circularly polarized light on size parameter of scatterer. The model reproduces the earlier results for the dependence of depolarization of circularly and linearly polarized light on scatterer size parameter. Further, the results obtained from this model show that for a given scatterer size parameter, a change in the value of ratio of refractive index of scatterer to that of the surrounding medium also significantly affects the degree of depolarization of both linearly and circularly polarized light. These results have been experimentally verified and can have important consequences for polarization gated optical imaging.

Picosecond pulse characterization using single-mode fibers

Abstract: We describe how spectral analysis of an ultrashort pulse after propagation in a single mode fiber can be used to characterize picosecond laser pulses. The technique is demonstrated for a cw mode locked Nd-YVO4 laser.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Depolarization of light in turbid medium: effect of collection geometry

Abstract: Larger depolarization of incident polarized light has been reported for tissues compared to tissue phantoms with matched optical thickness (? =?s × d, ?s being the scattering coefficient and d the physical thickness). We show that this arises because for the sample with larger ?s more multiply scattered photons are detected in a narrow collection angle typically used in experiments. These results were verified by time resolved studies on transmitted light as well as by Monte Carlo simulation.

Time shift of pulses due to dispersion: its slope, curvature, and onlinearity

Abstract: In this paper we show that the time delay of optical pulses travelign in long fibers is influenced by the dispersion, its slope, curvature and the fiber nonlinearity. It has been shown that they have significant role on the time shift of optical pulses. In addition, nonlinear time shift of pulses that is caused by the interaction of kerr nonlinearity with dispersion have been reported.