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1.
JPC – Journal of Planar Chromatography – Modern TLC - A water-in-oil microemulsion has been used for the first time as a mobile phase in thin-layer chromatography of amino acids. A new...  相似文献   
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Giloy Tulsi tablet is an Ayurvedic preparation containing Tinospora cordifolia (Giloy) and Ocimum sanctum (Tulsi) and it is recommended for boosting the body’s immune response. This research work is about the marker-based standardization of this Ayurvedic preparation using high-performance thin-layer chromatography method. Standardization is based on the determination and quantification of the phytoconstituents berberine and ursolic acid present in Giloy Tulsi tablets. Separation was performed on pre-coated silica gel 60 F254 plate as the stationary phase, with chloroform‒acetone‒formic acid (6:3.5:0.5, V/V) as the mobile phase. Identification and quantification were conducted densitometrically at 330 nm. The developed method resulted in good quality peak shape and enabled high-quality resolution of biomarkers. The RF value for berberine (0.46 ± 0.02) and for ursolic acid (0.68 ± 0.02) in both reference standard and formulation were found to be comparable. The method was validated for specificity, linearity, limit of detection, limit of quantification, intra-day and inter-day precisions, accuracy, and robustness. The limit of detection values were 91 and 153 ng/band for berberine and ursolic acid, respectively. The limit of quantification values were 175 and 465 ng/band for berberine and ursolic acid, respectively. Regression analysis of the calibration data revealed a good linear relationship between peak area response and concentration in the range 200‒1000 ng/band for berberine (r2 = 0.995) and 500‒2500 ng/band for ursolic acid (r2 = 0.9968). The accuracy of the method, determined by measurement of recovery at three different levels, was in the range 98‒102% for both markers. These results are indication of reliability, reproducibility, accuracy, and precision of the method.

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Dark currents n+/ν/p+ Hg0.69Cd0.31Te mid wave infrared photodiodes were measured at room temperature. The diodes exhibited negative differential resistance at room-temperature, but with increasing leakage currents as a function of reverse bias. The current–voltage characteristics were simulated and fitted by incorporating trap assisted tunneling via traps and Shockley–Read–Hall generation recombination process due to dislocations in the carrier transport equations. The thermal suppression of carriers was simulated by taking energy level of trap (Et), trap density (Nt) and the doping concentrations of n+ and ν regions as fitting parameters. Values of Et and Nt were 0.78Eg and ~6–9 × 1014 cm?3 respectively for most of the diodes. Variable temperature current voltage measurements on variable area diode array (VADA) structures confirmed the fact that variation in zero bias resistance area product (R0A) is related to gr processes originating from variation in concentration and kind of defects that intersect a junction area.  相似文献   
5.
Hg1−xCdxTe Metal–Insulator–Semiconductor (MIS) capacitors were studied both experimentally and theoretically to investigate the capacitance contributions due to band-to-band (btb) tunnelling and generation–recombination (gr) of carriers to inversion layer capacitance. A good fit to the data has been obtained by including the btb contributions rather than gr contributions.  相似文献   
6.
Prompt γ radiation following spontaneous fission has been measured using the EUROGAM 2 array. Using these data and newly developed analysis techniques a number of subjects were studied, which are briefly discussed. One of these subjects, shape transition in A≈100 Sr and Zr nuclei is discussed in more detail. Quadrupole moments were determined for rotational bands in the N=58,59,60,62 and 64 Sr and Zr isotopes. Deformation parameters, which increase from β2 ≈ 0.1 at N=56 to β2 ≈ 0.4 at N=64, suggest that in strontium and zirconium isotopes shape change happens gradually between N=56 and N=62 and is probably due to an occupancy of three or more deformation-driving orbitals of h11/2 parentage.  相似文献   
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The synthesis of various substituted 1-hydroxy-2-chloroacetyl-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt, 1-hydroxy-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt, 1-hydroxy-2-piperidinoacetyl-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt is described. The ir is also included.  相似文献   
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In this paper, we present a comparative study of polyaniline/polysaccharide composites (starch, carboxymethyl cellulose, cellulose acetate, and chitosan) by FTIR, UV-visible, SEM and electrochemical analysis. We propose that simultaneously three different phenomena happen while formation of composite system that may be listed as degradation of polysaccharide, polymerization of aniline, formation of polyaniline- polysaccharide composite. Effects of hydrochloric acid and oxidizing agent (ammonium peroxydisulphate) on the structure of polysaccharides were also investigated. We obtained dissimilar product yield and variable polyaniline and polysaccharide ratio in the composite system even though experimental conditions were same. The possible reasons responsible for the observed differences as well as characteristics and morphology of protonated and deprotonated composite materials are discussed.  相似文献   
9.
A new hexapyrrolic macrocycle composed of three naphthobipyrrole units has been synthesized which exhibited different emission changes with hydrogen pyrophosphate and benzoate ions. Phosphate ions caused red shifting of the fluorescence band of calixnaphthobipyrrole while benzoate ions resulted in quenching of the same. The fluorescence quenching was further utilized for investigating binding preferences of the probe with neutral aromatic guest molecules substituted with groups having varied electron withdrawing abilities. The extent of quenching with the neutral guests increased with the increasing electron deficiency on the aromatic ring of the guest. The fluorescence quenching has been ascribed to electron transfer from the host to the guest species.  相似文献   
10.
JPC – Journal of Planar Chromatography – Modern TLC - The thin-layer chromatography of eighteen anions has been performed on silica layers with mixed aqueous–organic mobile...  相似文献   
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