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121.
122.
Solomon Legese Hailu Balachandran Unni Nair Mesfin Redi-Abshiro Isabel Diaz Rathinam Aravindhan Merid Tessema 《催化学报》2016,(1):135-145
将Fe(Ⅲ),Ni(Ⅲ)和Cu(Ⅱ)与N,N'-双邻羟苯亚甲基-1,2-苯二胺配位的络合物封装在Y分子筛内,作为多相类Fenton的高级氧化过程的催化剂,用于降解4-氯-3-甲基苯酚(PCMC).采用粉末X射线衍射、热重、N2吸附-脱附、红外光谱、元素分析和扫描电镜对所制催化剂的物化性质进行了表征,并考察了H2O2的初始浓度、催化剂用量、温度和pH值等因素对模型有机污染物降解的影响.结果表明,在Fe(Ⅲ),Ni(Ⅲ)和Cu(Ⅱ)催化剂作用下,在较低的酸性pH值、催化剂用量0.1 g、H2O2的初始浓度0.35 mmol/L的条件下,于50℃反应120 min几乎可以完全去除PCMC.同时还考察了所制PCMC降解催化剂的重复使用性能,提出了可能的催化剂失活机理,也研究了PCMC氧化过程中可能的中间产物和动力学. 相似文献
123.
124.
We report here a new and fast approach [Transferable Partial Atomic Charge Model (TPACM4)-upto four bonds] for deriving the partial atomic charges of small molecules for use in protein/DNA-ligand docking and scoring. We have created a look-up table of 5302 atom types to cover the chemical space of C, H, O, N, S, P, F, Cl, and Br atoms in small molecules together with their quantum mechanical RESP fit charges. The atom types defined span diverse plausible chemical environments of each atom in a molecule. The partial charge on any atom in a given molecule is then assigned by a reference to the look-up table. We tested the sensitivity of the TPACM4 partial charges in estimates of hydrogen bond dimers energies, solvation free energies and protein-ligand binding free energies. An average error ±1.11 kcal/mol and a correlation coefficient of 0.90 is obtained in the calculated protein-ligand binding free energies vis-à-vis an RMS error of ±1.02 kcal/mol and a correlation coefficient of 0.92 obtained with RESP fit charges in comparison to experiment. Similar accuracies are realized in predictions of hydrogen bond energies and solvation free energies of small molecules. For a molecule containing 50-55 atoms, the method takes on the order of milliseconds on a single processor machine to assign partial atomic charges. The TPACM4 programme has been web-enabled and made freely accessible at http://www.scfbio-iitd.res.in/software/drugdesign/charge.jsp. 相似文献
125.
H. V. V. Prasad Jayaram K. Sankaran 《The Journal of the Operational Research Society》1996,47(7):895-905
This paper describes the application of network modeling and optimization for short-term distribution planning in an Indian electronica firm. The company has three production centres, each comprising several factories. Each day, it ships finished product from the three production centres to 23 distribution centres (namely, its branches and sub-branches) spread all over the country. The present problem may be stated as: given the planned production quantity at each production centre and the estimated demand at each distribution centre for each week of a given month, specify the quantities to be dispatched from each production centre to the various distribution centres in each week of the month. The problem is modelled as a multi-period, minimum-cost, network flow model for each product item. The paper also discusses the implementation and actual use of the model for monthly distribution planning at the company. 相似文献
126.
P. N. Jayaram Gouriprasanna Roy Govindasamy Mugesh 《Journal of Chemical Sciences》2008,120(1):143-154
The keto-enol type tautomerism in anti-thyroid drugs and their selenium analogues are described. The commonly used anti-thyroid
drug methimazole exists predominantly in its thione form, whereas its selenium analogue exists in a zwitterionic form. To
understand the effect of thione/thiol and selone/selenol tautomerism on the inhibition of peroxidase-catalysed reactions,
we have synthesized some thiones and selones in which the formation of thiol/selenol forms are blocked by different substituents.
These compounds were synthesized by a carbene route utilizing an imidazolium salt. The crystal structures of these compounds
reveal that the C=Se bonds in the selones are more polarized than the C=S bonds in the corresponding thiones. The structures
of selones were studied in solution by NMR spectroscopy and the 77Se NMR chemical shifts for the selones show large upfield shifts in the signals, confirming their zwitterionic structures
in solution. The inhibition of lactoperoxidase by the synthetic thiones indicates that the presence of a free N-H moiety is
essential for an efficient inhibition. In contrast, such moiety is not required for an inhibition by the selenium compounds. 相似文献
127.
Synthesis of cadmium sulphide in pure and mixed Langmuir-Blodgett films of n -octadecylsuccinic acid
G. Hemakanthi Balachandran Unni Nair Aruna Dhathathreyan 《Journal of Chemical Sciences》2000,112(2):109-118
Cadmium sulphide (CdS) nanoparticles were grown by the reaction of sodium sulphide (Na2S) with Langmuir-Blodgett (LB) films of cadmium salts ofn-octadecylsuccinic acid (ODSU) and with LB films of ODSU in mixtures of octadecylamine and octadecyl alcohol. The results
indicate that heterogeneous nucleation and aggregation in the pure ODSU LB films due to processes like Ostwald ripening are
destabilized by the presence of the long-chain amine and alcohol in mixed systems. CdS nanoparticles in the LB films were
monitored by UV-visible absorption spectra, which allow an estimation of the size of the particles. The morphology, size and
nature of the nanocrystallites formed depend on whether the sulphidation was done on the pure film or in the mixed films.
It is seen that particles of size around 1.6 nm were formed in ODSU/octadecylalcohol and ODSU/ octadecylamine mixed LB films
while in pure ODSU films the size was about 2.7 nm. These films showed typical needle-shaped structures, as observed by the
optical microscopic technique. Mean size and morphology were confirmed by transmission and scanning electron microscopy, while
selective area electron diffraction patterns showed six-fold symmetry and indicated that the CdS crystals grow epitaxially
with respect to the monolayer. Further, the crystallisation enhanced in the mixed LB films showed a characteristic zinc oxide
(Wurtzite) structure compared with the pure ODSU matrix. 相似文献
128.
The paper presents two different methods to calculate the current density along silicone rubber (SiR) insulator surface under salt-fog testing conditions. The first method which is based on field theory approach uses the commercial software COMSOL® to compute the current density. The conductivity of the contamination layer used in the calculations was extracted from the measured equivalent salt deposit density (ESDD) separately for different regions of the insulator surfaces. The second method is based on circuit theory approach. The insulator surface was divided into different sections for resistance calculations to account for different contamination levels. Rankings based on the calculated current densities based on segmentation of the insulator surface for ESDD measurements match with those extracted from measured leakage currents. 相似文献
129.
Kalarical Janardhanan Sreeram Marimuthu Nidhin Balachandran Unni Nair 《Colloids and surfaces. B, Biointerfaces》2009,71(2):260-267
Iron oxide nanoparticles are being viewed with interest owing to the great potential they have in the biomedical applications like MRI contrast enhancement, targeted drug delivery, hyperthermia and recently in magnetic separation of cancer cells from the body. Templated synthesis has been considered ideal for synthesis of iron oxide nanoparticles as particles are attracted magnetically, in addition to usual flocculation through van der Waals attraction. Biological templates are attractive owing to their biocompatibility and the attractive porosity and surface chemistry that nature provides. Polysaccharides like chitosan and alginate have been employed in the synthesis of a polyion complex, which provided the active-binding sites for iron(II) ions in solution to bind. The natural organization of chitosan and alginate into a porous film has been exploited to synthesize spherical iron oxide nanoparticles through careful calcination of the iron(II) conjugate film. Our experiments indicate that the formed nanoparticles are highly crystalline, confirm to the hematite structure and have a superparamagnetic response with a low coercivity of 116 Oe. Particles thus synthesized were highly monodisperse with hydrodynamic diameter of 1.8 nm. The symmetric porosity of the film translates into the synthesis of well-aligned nanoparticles of iron oxide. Compared to synthesis in solution, the film-assisted synthesis offered a greater degree of control over the particle size distribution pattern, with the chitosan–alginate template providing the needed spatial separation to prevent the aggregation due to magnetostatic coupling. Such hematite nanoparticles can either be used directly or converted to paramagnetic magnetite by reduction. Zeta potential measurements indicate highly stable nanoparticles, which can therefore be conjugated to cationic liposomes carrying drugs and magnetically guided to target sites. 相似文献
130.
S. R. Jayaram 《Graphs and Combinatorics》1987,3(1):357-363
A setS of lines is a line dominating set if every line not inS is adjacent to some line ofS. The line domination number of a graph is the cardinality of a minimum line dominating set. In this paper we study the line dominating sets and obtain bounds for the line domination number. Also, Nordhaus-Gaddum type results are obtained for the line domination number and the line domatic number. 相似文献