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141.
Penta NK Dandu Veera PR Babu SV 《Langmuir : the ACS journal of surfaces and colloids》2011,27(7):3502-3510
A cationic polymer, poly(diallyldimethylammonium chloride), or PDADMAC (MW ≈ 200,000), at a concentration of 250 ppm was used to enhance polysilicon removal rates (RRs) to ~600 nm/min while simultaneously suppressing both silicon dioxide and silicon nitride RRs to <1 nm/min, both in the absence or in the presence of ceria or silica abrasives during chemical mechanical polishing (CMP). These results suggest that aqueous abrasive-free solutions of PDADMAC are very attractive candidates for several front-end-of-line (FEOL) CMP processes. Possible mechanisms for the enhancement of poly-Si RR and the suppression of oxide and nitride RRs are proposed on the basis of the RRs, contact angle data on poly-Si films, zeta potentials of polishing pads, polysilicon films, silicon nitride particles, and silica and ceria abrasives, thermogravimetric analysis, and UV-vis spectroscopy data. 相似文献
142.
Avula B Khan SI Tekwani BL Nanayakkara NP McChesney JD Walker LA Khan IA 《Biomedical chromatography : BMC》2011,25(9):1010-1017
The clinical formulation of primaquine (PQ) is a mixture of (−)‐(R)‐ and (+)‐(S)‐ primaquine enantiomers which may show different pharmacokinetic and pharmacodynamic properties. To assess the efficacy and toxicity of primaquine enantiomers, a method using LC‐MSD‐TOF has been developed. The enantiomers were well separated using a Chiralcel OD column (250 × 4.6 mm, 10 µm) with a linear gradient of mobile phase consisting of acetonitrile (0.1% formic acid) and aqueous ammonium formate (20 mm ; 0.1% formic acid) adjusted to pH 5.9 at a flow rate of 0.7 mL/min. The method was validated for linearity, precision, accuracy and limits of detection and quantification. The calibration curves were linear with all correlation coefficients being >0.999. The average recoveries of (−)‐(R)‐ and (+)‐(S)‐primaquine and (−)‐(R)‐ and (+)‐(S)‐carboxyprimaquine were 88 and 92%, respectively, in spiked human plasma and 89 and 93% respectively in spiked mouse plasma samples. The RSD of (−)‐(R)‐ and (+)‐(S)‐primaquine and (−)‐(R)‐ and (+)‐(S)‐carboxyprimaquine were 2.15, 1.74, 1.73 and 2.31, respectively, in spiked human plasma and 2.21, 1.09, 1.95 and 1.17% in spiked mouse plasma, respectively. The intra‐day and inter‐day precisions expressed as RSD were lower than 10% in all analyzed quality control levels. The method as reported is suitable for study of the pharmacokinetic and pharmacodynamic properties of the enantiomers of primaquine. The method was successfully applied to study plasma pharmacokinetic profile of enantiomers of primaquine and carboxyprimaquine in mice administered with primaquine in racemic form. The analytical method was found to be linear, accurate, precise and specific. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
143.
144.
The solvent extraction behavior of multiple proton ionizable p-tert-butylcalix[4]arene and [6]arene carboxylic acid derivatives towards indium has been investigated along with an acyclic monomeric analogue from weakly acidic media into chloroform. The extraction mechanism is ion exchange and carboxylic acid groups are adequate ligating sites for extraction. The cyclic structure of calixarene ligands to accommodate the potential guest species and the cooperativity effect of multifunctional groups significantly affect the complexation behavior and calixarene derivatives are found to be excellent extractants over the monomeric analogue. The composition of the extracted complex depends on the solution pH and attempts to determine the composition of the extracted complex for the extraction of indium have been stymied by complications arising from the formation of polynuclear species of indium and bridged polymeric species of calixarene carboxylic acid derivatives. One mole of calix[4]arene derivative extracts 2.5 moles of indium whereas the calix[6]arene derivative tends to extract 4.0 moles of indium. The loaded indium is back extracted with 1 mol dm(-3) hydrochloric acid solution. Though quantitative back extraction of indium was achieved from the fully loaded calix[6]arene derivative, it was only achieved up to 85% in the case of the calix[4]arene derivative. 相似文献
145.
Oscar Salas-Solano Kunnel Babu SungAe Suhr Park Xinfeng Zhang Li Zhang Zoran Sosic Boris Boumajny Ming Zeng Kuang-Chuan Cheng Angelia Reed-Bogan Stacey Cummins-Bitz David A. Michels Monica Parker Paulina Bonasia Mingfang Hong Steven Cook Margaret Ruesch David Lamb Dora Bolyan Steffen Kiessig Darren Allender Brian Nunnally 《Chromatographia》2011,73(11-12):1137-1144
Interlaboratory comparisons are essential to bringing emerging technologies into biopharmaceutical industry practice and regulatory acceptance. As a result, an international team including 12 laboratories from 10 independent biopharmaceutical companies in the United States and Switzerland was formed to evaluate the precision and robustness of capillary isoelectric focusing (CIEF) to assess the charge heterogeneity of monoclonal antibodies. The different laboratories determined the apparent pI and the relative distribution of the charge isoforms of a representative monoclonal antibody (rMAb) sample using the same CIEF method. Statistical evaluation of the data was performed to determine within and between-laboratory consistencies and outlying information. The apparent pI data generated for each charge variant peak showed very good precision between laboratories with percentage of RSD values of ??0.5%. Similarly, the percentage of RSD for the rMAb charge variants percent peak area values are ??4.4% across different laboratories with different analysts using different lots of ampholytes and multiple instruments. Taken together, these results validate the appropriate use of CIEF in the biopharmaceutical industry in support of regulatory submissions. 相似文献
146.
Bose SK Geetharani K Sahoo S Reddy KH Varghese B Jemmis ED Ghosh S 《Inorganic chemistry》2011,50(19):9414-9422
The reaction of [Cp*TaCl(4)], 1 (Cp* = η(5)-C(5)Me(5)), with [LiBH(4)·THF] at -78 °C, followed by thermolysis in the presence of excess [BH(3)·THF], results in the formation of the oxatantalaborane cluster [(Cp*Ta)(2)B(4)H(10)O], 2 in moderate yield. Compound 2 is a notable example of an oxatantalaborane cluster where oxygen is contiguously bound to both the metal and boron. Upon availability of 2, a room temperature reaction was performed with [Fe(2)(CO)(9)], which led to the isolation of [(Cp*Ta)(2)B(2)H(4)O{H(2)Fe(2)(CO)(6)BH}], 3. Compound 3 is an unusual heterometallic boride cluster in which the [Ta(2)Fe(2)] atoms define a butterfly framework with one boron atom lying in a semi-interstitial position. Likewise, the diselenamolybdaborane, [(Cp*Mo)(2)B(4)H(4)Se(2)], 4 was treated with an excess of [Fe(2)(CO)(9)] to afford the heterometallic boride cluster [(Cp*MoSe)(2)Fe(6)(CO)(13)B(2)(BH)(2)], 5. The cluster core of 5 consists of a cubane [Mo(2)Se(2)Fe(2)B(2)] and a tricapped trigonal prism [Fe(6)B(3)] fused together with four atoms held in common between the two subclusters. In the tricapped trigonal prism subunit, one of the boron atoms is completely encapsulated and bonded to six iron and two boron atoms. Compounds 2, 3, and 5 have been characterized by mass spectrometry, IR, (1)H, (11)B, (13)C NMR spectroscopy, and the geometric structures were unequivocally established by crystallographic analysis. The density functional theory calculations yielded geometries that are in close agreement with the observed structures. Furthermore, the calculated (11)B NMR chemical shifts also support the structural characterization of the compounds. Natural bond order analysis and Wiberg bond indices are used to gain insight into the bonding patterns of the observed geometries of 2, 3, and 5. 相似文献
147.
Suresh Babu Meruva A. Raghunadh N. Anil Kumar U. K. Syam Kumar R. Vasu Dev P. K. Dubey 《Journal of heterocyclic chemistry》2011,48(3):540-548
A variety of 5‐aryl‐(20S)‐camptothecin derivatives were synthesized by the reaction of 5‐hydroxy‐(20S)‐camptothecin with aromatic hydrocarbons under Friedel‐Craft reaction conditions in moderate to good yield as diastereomeric pairs. The methodology was then extended for the synthesis of 5‐amido‐(20S)‐camptothecin derivatives by reacting 5‐hydroxy‐(20S)‐camptothecin with alkyl and aryl nitriles under Ritter type reaction conditions. The reaction is presumed to proceed through an iminium ion intermediate under Friedel Craft and Ritter type reaction condition, which is further trapped by nucleophile present in the reaction medium. J. Heterocyclic Chem., 00 , 00 (2011). 相似文献
148.
Babu KR Lingam ChB Tewari SP Vaitheeswaran G 《The journal of physical chemistry. A》2011,115(17):4521-4529
The structural, electronic, optical, and vibrational properties of LiN(3) under high pressure have been studied using plane wave pseudopotentials within the generalized gradient approximation for the exchange and correlation functional. The calculated lattice parameters agree quite well with experiments. The calculated bulk modulus value is found to be 23.23 GPa, which is in good agreement with the experimental value of 20.5 GPa. Our calculations reproduce well the trends in high-pressure behavior of the structural parameters. The present results show that the compressibility of LiN(3) crystal is anisotropic and the crystallographic b-axis is more compressible when compared to a- and c-axes, which is also consistent with experiment. Elastic constants are predicted, which still awaits experimental confirmation. The computed elastic constants clearly show that LiN(3) is a mechanically stable system and the calculated elastic constants follow the order C(33) > C(11) > C(22), implying that the LiN(3) lattice is stiffer along the c-axis and relatively weaker along the b-axis. Under the application of pressure the magnitude of the electronic band gap value decreases, indicating that the system has the tendency to become semiconductor at high pressures. The optical properties such as refractive index, absorption spectra, and photoconductivity along the three crystallographic directions have been calculated at ambient as well as at high pressures. The calculated refractive index shows that the system is optically anisotropic and the anisotropy increases with an increase in pressure. The observed peaks in the absorption and photoconductivity spectra are found to shift toward the higher energy region as pressure increases, which implies that in LiN(3) decomposition is favored under pressure with the action of light. The vibrational frequencies for the internal and lattice modes of LiN(3) at ambient conditions as well as at high pressures are calculated from which we predict that the response of the lattice modes toward pressure is relatively high when compared to the internal modes of the azide ion. 相似文献
149.
Sangeetha K Babu RR Ramamurthi K Prakash J Khan SA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):884-888
L-arginine hydrochloride monohydrate and L-arginine hydrobromide monohydrate single crystals are irradiated by 100 MeV Ag8+ swift heavy ions. The residual gases liberated from the irradiated samples are monitored as a function of ion fluence using quadrupole mass analyzer. The C2H3+, C2H2, N2, CO, HCl and CO2 are the dominant gases liberated. Fourier transform infrared spectra of irradiated crystals explain the breaking of bonds in a localized region of the crystals. The crystallinity of irradiated crystals is analyzed by powder X-ray diffractions. 相似文献
150.
Babu SS Saeki A Seki S Möhwald H Nakanishi T 《Physical chemistry chemical physics : PCCP》2011,13(11):4830-4834
The coassembly of C(60) derivatives through arene-perfluoroarene interactions has been used for the first time to develop millimeter-sized flat crystalline sheets. Time-resolved microwave conductivity (TRMC) measurements exhibited anisotropic features with over double the charge carrier mobility in the direction parallel to the plane of the crystal than perpendicular to the plane. This study demonstrates a strategy to obtain large-sized 2-dimensional architectures of C(60) with anisotropic optoelectronic functions. 相似文献