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1.
A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of nevirapine both as a bulk drug and in formulations was developed and validated. The solvent system consisted of toluene-carbon tetrachloride-methanol-acetone-ammonia (3.5:3.5:2.0:1.0:0.05, v/v/v/v/v). Densitometric analysis of nevirapine was carried out in the absorbance mode at 289nm. This system was found to give compact spots for nevirapine (R(f) value of 0.44+/-0.02). Nevirapine was subjected to acid and alkali hydrolysis, oxidation, dry heat and wet heat treatment and photodegradation. The drug undergoes degradation under acidic, basic conditions and oxidation. Also the degraded products were well resolved from the pure drug with significantly different R(f) values. Linearity was found to be in the range of 30-1000ng/spot with significantly high value of correlation coefficient. The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.998+/-0.002 in the working concentration range of 300ng/spot to 1000ng/spot. The mean value of slope and intercept were 0.073+/-0.005 and 36.78+/-1.50, respectively. The method was validated for precision, robustness and recovery. The limit of detection and quantitation were 5 and 10ng/spot, respectively. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid degradation process. Arrhenius plot was constructed and activation energy was calculated. 相似文献
2.
Mechanically stable and corrosion resistant superhydrophobic sol-gel coatings on copper substrate 总被引:1,自引:0,他引:1
A. Venkateswara Rao Sanjay S. LattheSatish A. Mahadik Charles Kappenstein 《Applied Surface Science》2011,257(13):5772-5776
Development of the anticorrosion coatings on metals having both passive matrix functionality and active response to changes in the aggressive environment has raised tremendous interest in material science. Using a sol-gel deposition method, superhydrophobic copper substrate could be obtained. The best hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as 7 M NH4OH) at a molar ratio of 1:19.1:4.31 respectively. The surface morphological study showed the ball like silica particles distributed on the copper substrate with particle sizes ranging from 8 to 12 μm. The coatings showed the static water contact angle as high as 155° and the water sliding angle as low as 7°. The superhydrophobic nature was maintained even though the deposited copper substrate was soaked for 100 h in 50% of HCl solution. The coatings are stable against humidity and showed superhydrophobic behavior even after 90 days of exposure. The coatings are mechanically stable and water drops maintained the spherical shape on the bent copper substrate, which was bent more than 90°. 相似文献
3.
R. Mateva KR. Zhilkova G. Zamfirova R. Díaz‐Calleja A. Garcia‐Bernabé 《Journal of Polymer Science.Polymer Physics》2010,48(23):2518-2529
The molecular dynamics of new poly (ω‐dodecalactam‐co‐ε‐caprolactam‐co‐propylene oxide) copolymers (DL/CL/PAC) has been investigated by using dynamic mechanical thermal analysis (DMTA) and dielectric relaxation spectroscopy (DRS) measurements. The copolymers were synthesized via anionic polymerization of relevant lactams activated with carbamoyl derivatives of telechelic hydroxyl terminated polypropylene oxide with isophorone diisocyanate (PAC). The calorimetric, X‐ray diffraction, and DMTA measurements were performed to recognize the influence of the composition ratio and the type of PAC on the physical, thermal, and mechanical properties of the synthesized copolymers. The DRS was used to study the frequency dependence of the dielectric permittivity of some isotherms from ?110 to 145 °C. Copolymerization of ε‐caprolactam with about 10 wt % ω‐dodecalactam results in a copolymer that has lower water absorption, a melting point close to that of polyamide 6 and has a high enough degree of crystallinity in respect to high storage modulus. Five dielectric relaxations have been observed in the dielectric spectra, three at lower temperature and two at higher temperature. The copolymers have two glass transition temperatures for polyamide segments and polyether blocks, indicating microphase separation in the copolymers. Other studies directed toward molecular dynamics of polyamide DL/CL/PAC copolymers have not been reported. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
4.
B. S. Mohite B. E. Mahadik A. S. Jadhav 《Journal of Radioanalytical and Nuclear Chemistry》2000,245(2):343-346
A simple column chromatographic method has been developed for the separation of thorium(IV) from associated elements using poly-(dibenzo-18-crown-6). The separations are carried out from picric acid medium. The adsorption of thorium(IV) was quantitative from 0.0005–0.05M picric acid. Amongst the various eluents tested, 2.0–8.0M HCl, HBr, 1.0–6.0M HClO4 and 5.0M acetic acid were found to be particularly efficient for the quantitative elution of thorium(IV). The capacity of poly-(dibenzo-18-crown-6) for thorium(IV) was found to be 1.29±0.01 mmol/g of crown polymer. Thorium(IV) was separated from a number of cations in binary mixtures in which most of the cations showed a very high tolerance limit. It was possible to separate thorium(IV) from a number of cations such as lanthanum(III), yttrium(III), uranium(VI), beryllium(II) and barium(II) in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand. It is possible to separate and determine 5 ppm of thorium(IV) by this method. The method is very simple, rapid, selective and has good reproducibility (approximately ±2%). 相似文献
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Mahadik Satish A. Mahadik D. B. Parale V. G. Wagh P. B. Gupta Satish Venkateswara Rao A. 《Journal of Sol-Gel Science and Technology》2012,62(3):490-494
A facile route to methyltrimethoxysilane (MTMS) based recoverable superhydrophobic silica coatings with dual-scale roughness
obtained through the single step base catalyst sol–gel process. Superhydrophobic silica coatings have shown static water contact
angle near about 170 ± 1° and dynamic water contact angle up to 2 ± 1°. Superhydrophobic-superhydrophilic switching feature
also achieved by alternating heat treatment and bath surface modification with Trimethylchlorosilane (TMCS) at room temperature
(26 °C). Furthermore, the superhydrophobic state could be transformed into superhydrophilic state by slow rate heat treatment.
These studies present a very simple strategy for the fabrication of recoverable superhydrophobic surfaces. 相似文献
7.
Kaul Neeraj Agrawal Himani Paradkar Anant Raghunath Mahadik Kakasaheb Ramoo 《平面色谱法杂志一现代薄层色谱法》2004,17(4):264-274
JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, selective, precise, and stability-indicating high-performance thin-layer chromatographic method has been established... 相似文献
8.
A series of 1,3-diaryl-2-propen-1-ones and their indole analogs were synthesized and evaluated for antibacterial activity.
Structures of newly synthesized compounds were confirmed by physicochemical, spectral and elemental analysis. All the compounds
were screened for their antibacterial activities against four different bacterial strains. The QSAR studies were performed
using Vlife MDS 3.5 software. QSAR equation revealed that selected electronic, steric and lipophilic parameters have good
correlation with antibacterial activity. Best equations were selected on basis of the correlation coefficient (r
2) and the predictable ability of the equations. The present findings suggest that the 1,3-diaryl-2-propen-1-ones framework
is an attractive template for structure optimization to achieve higher potency, lower toxicity, and a wider spectrum of antibacterial
activity. 相似文献
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N.A. Mahadik S.B. Qadri M.V. Rao J.P. Yesinowski 《Applied Physics A: Materials Science & Processing》2007,86(1):67-71
Free-standing GaN films grown by hydride vapor phase epitaxy (HVPE) on c-plane sapphire have been studied for in-plane anisotropic strain. Lattice parameters are obtained from high-resolution X-ray diffraction data and the film quality is determined by measuring the rocking curves and by 71Ga nuclear magnetic resonance (NMR). The in-plane strain was determined using grazing incidence X-ray diffraction and conventional X-ray measurements. It is found that the in-plane lattice parameter varies with depth and has estimated surface strain anisotropy of 4.0791×10-3 up to a thickness of 0.3 μm. The 71Ga NMR experiments reveal different degrees of inhomogeneity amongst the three samples. This is shown by the appearance of an additional broad central-transition peak shifted to higher frequency by a Knight shift from conduction electrons in sample regions having high carrier concentrations. PACS 72.80.Ey; 61.10.-i; 61.72.Hh 相似文献