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81.
Rastogi SC Zachariae C Johansen JD Devantier C Menné T 《Journal of chromatography. A》2004,1031(1-2):315-317
An increased frequency of contact allergy to methyldibromoglutaronitrile (MDBGN), a commonly used preservative in cosmetics and other consumer products, has been reported in recent years. A high-performance liquid chromatography (HPLC) method for the determination of MDBGN in cosmetic products has been validated in the present study. The identification is performed by reductive electrochemical detection of the bromine present in the molecule. The method is suitable for compliance testing of cosmetic products as well as for the research to support clinical and epidemiological studies. 相似文献
82.
The paper proposes a maximum-likelihood (ML) method based on spectral estimation theory for the estimation of phase distribution in interferometry in the presence of nonsinusoidal waveforms, noise, and the miscalibration of the piezoelectric device. The proposed method also allows the use of arbitrary phase steps. ML estimators are asymptotically efficient for large number of data samples. The method is complemented well by the incorporation of global search algorithm known as Probabilistic Global Search Lausanne for minimizing the ML function. The performance of the proposed method is studied in the presence of noise. 相似文献
83.
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85.
The mechanism of the following solid-state reactions between bismuth(III) oxide and molybdenum(VI) oxide was investigated within the temperature range 400–650°C. Two types of experiments, capillary and particle size, were performed to ascertain whether MoO3 diffuses into Bi2O3 or vice versa. These show that molybdenum trioxide diffuses into bismuth oxide grains. If α is the fraction of molybdenum trioxide reacted, the kinetics in all five cases are found to be governed by the equation αn = kt throughout the temperature range, where n and k are constants at a given temperature and t is the time. Both n and k are temperature dependent. The characteristic feature of these reactions is that they proceed to completion. Results are also fitted by the relation , where k2 and k3 are constants, which shows that the reactions occur by bulk diffusion through grain boundary contacts. The number of grain boundary contact points decreases with time in the course of reaction. 相似文献
86.
V. K. Rastogi Surabhi Singhal M. A. Palafox G. Ramana Rao 《Indian Journal of Physics》2010,84(2):151-165
The FTIR spectrum of 2, 5-difluorobenzonitrile has been recorded in the region 200–4000 cm−1 (in liquid phase). The laser Raman spectrum in the range of 0–3500 cm−1 (in liquid phase) has also been recorded. The spectra have been analyzed assuming C
s
point group symmetry for the molecule. A zero-order normal coordinate analysis has been made for the molecule using force
constants derived earlier. On the basis of potential energy distributions and eigen vectors unambiguous vibrational assignments
have been made for all the fundamentals of the molecule. Thermodynamic functions have also been computed in the temperature
range 200–1000 K by utilizing the observed fundamental frequencies assuming rigid-rotor harmonic oscillator approximation. 相似文献
87.
Mazaahir Kidwai Kavita Singhal Shweta Rastogi 《Journal of heterocyclic chemistry》2006,43(5):1231-1236
An expeditious and convenient solid supported synthesis of 1,3,7‐triaryl‐6‐phenyl‐2‐thioxo‐1,2,3,7‐tetrahydropyrrolo [2,3‐d]pyrimidin‐4‐one derivatives from readily accessible N,N‐disubstituted thiobarbituric acids under microwaves utilising Paal Knorr reaction is described. 相似文献
88.
Kireev AS Nadein ON Agustin VJ Bush NE Evidente A Manpadi M Ogasawara MA Rastogi SK Rogelj S Shors ST Kornienko A 《The Journal of organic chemistry》2006,71(15):5694-5707
Pancratistatin is a potent anticancer natural product, whose clinical evaluation is hampered by the limited natural abundance and the stereochemically complex structure undermining practical chemical preparation. Fifteen aromatic analogues of conduritol F, l-chiro-inositol, and dihydroconduritol F that possess four of the six pancratistatin stereocenters have been synthesized and evaluated for anticancer activity. These compounds serve as truncated pancratistatin analogues lacking the lactam ring B, but retaining the crucial C10a-C10b bond with the correct stereochemistry. The lack of activity of these compounds provides further insight into pancratistatin's minimum structural requirements for cytotoxicity, particularly the criticality of the intact phenanthridone skeleton. Significantly, these series provide rare examples of simple aromatic conduritol and inositol analogues and, therefore, this study expands the chemistry and biology of these important classes of compounds. 相似文献
89.
We propose a new approach for estimating the phase in the presence of a nonlinear response of a phase-shifting device: a piezoelectric transducer (PZT). The method is complemented well by the high resolution and the maximum likelihood estimation techniques in the estimation of the phase step and the nonlinear coefficient. The advantage of the proposed method is that it can be extended to the extraction of multiple phases in configurations involving multiple PZTs in the presence of nonlinearity. Symmetricity in the phase steps is not required in this method. Hence hysteresis of the PZT does not have any influence on the accuracy of the phase estimation. The effectiveness of the method is shown by experimental results. 相似文献
90.
We have studied the peak effect (PE) phenomenon in single crystals of weakly pinned superconductors CeRu2 and 2H-NbS2. 2H-NbS2 is iso-structural and iso-electronic to 2H-NbSe2, whose similarity with CeRu2 as regards the PE representing the order-to-disorder transformation of the flux line lattice was claimed some time ago. We
report on the step change in equilibrium magnetization across the peak effect in CeRu2. We also present the vortex phase diagram of 2H-NbS2 obtained from the magnetization data, and compare the PE phenomenon in 2H-NbS2 and 2H-NbSe2. 相似文献