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101.
The paper presents a generalized economic manufacturing quantity model for an unreliable production system in which the production facility may shift from an ‘in-control’ state to an ‘out-of-control’ state at any random time (when it starts producing defective items) and may ultimately break down afterwards. If a machine breakdown occurs during a production run, then corrective repair is done; otherwise, preventive repair is performed at the end of the production run to enhance the system reliability. The proposed model is formulated assuming that the time to machine breakdown, corrective and preventive repair times follow arbitrary probability distributions. However, the criteria for the existence and uniqueness of the optimal production time are derived under general breakdown and uniform repair time (corrective and preventive) distributions. The optimal production run time is determined numerically and the joint effect of process deterioration, machine breakdowns and repairs (corrective and preventive) on the optimal decisions is investigated for a numerical example. 相似文献
102.
Swagata Chakraborty Susmitha A. L. Ramakrishna V. Hosur 《Magnetic resonance in chemistry : MRC》2012,50(9):587-591
Direct detection of 13C nucleus can be used as a valuable alternative where 1H detection poses a challenge due to relaxation effects, chemical exchange and poor chemical shift dispersion. In this context, we have designed a suite of 2D 13Cα‐detected hNCA experiments that provide sequential correlations of 13Cα with 15N on one hand and efficient spectroscopic labeling of certain groups of residues, namely, Gly, Ala, Ser and Thr, on the other. These residues act as checkpoints in the sequential walk, which in turn offer new possibilities of backbone assignment of small proteins from a set of 2D experiments, thereby providing great economy in terms of spectrometer time. The direct identification of peptide segments around Gly, Ala, Ser and Thr residues along a protein chain will be highly valuable for deriving important information on sites of ligand binding, phosphorylation, inhibitor/substrate binding, understanding protein folding pathways, comprehending local conformational dynamics etc. without having to obtain complete sequence‐specific assignments, which can be time consuming and at times formidable, especially in large proteins. We have illustratively demonstrated the multifaceted applications of these variants of 2D experiments on ubiquitin and M‐crystallin. We foresee that these 2D hNCA experiments will provide economic and efficient strategies for studying the structure and function of proteins. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
103.
Chakraborty S Chaudhuri S Pahari B Taylor J Sengupta PK Sengupta B 《Journal of luminescence》2012,132(6):1522-1528
Hesperitin, a ubiquitous bioactive flavonoid abundant in citrus fruits is known to possess antioxidant, anti-carcinogenic, hypolipidemic, vasoprotective and other important therapeutic properties. Here we have explored the interactions of hesperitin with normal human hemoglobin (HbA), using steady state and time resolved fluorescence spectroscopy, far UV circular dicroism (CD) spectroscopy, combined with molecular modeling computations. Specific interaction of the flavonoid with HbA is confirmed from flavonoid-induced static quenching which is evident from steady state fluorescence as well as lifetime data. Both temperature dependent fluorescence measurements and molecular docking studies reveal that apart from hydrogen bonding and van der Waals interactions, electrostatic interactions also play crucial role in hesperitin-HbA interactions. Furthermore, electrostatic surface potential calculations indicate that the hesperitin binding site in HbA is intensely positive due to the presence of several lysine and histidine residues. 相似文献
104.
105.
Here, we construct infinitely many number fields of any given degree d>1 whose class numbers have many prime factors. 相似文献
106.
A. Banerjee Tanwi Ghosh Subenoy Chakraborty 《General Relativity and Gravitation》2001,33(7):1139-1145
Exact solutions are obtained for a special case of locally rotationally symmetric Bianchi I models consisting of a dilaton scalar field and a Liouville type dilatonic potential interacting with an electromagnetic field coupled with gravity, and the corresponding properties of the space-time are discussed. 相似文献
107.
Birefringent filters can be used for tuning lasers, with some advantages over prisms, gratings and tilted etalons. In this paper the transmission characteristics of a new mixed birefringent filter are investigated. The term ‘mixed’ is used because both circular birefringence and linear birefringence have been utilized in the fabrication of this filter.It has a loss-less core, formed by a cascaded system of alternate rotators and retarders, and a linear polarizer at each end. The performance of this filter is better because of the more effective suppression of side peaks. Unlike previous birefringent filters, this one may be used inside a linear resonator. 相似文献
108.
Soumya Basu Basab Chattopadhyay A. Ganguly P. Chakraborty P. Roy Chowdhury S. Samanta M. Mukherjee A. K. Mukherjee S. K. Choudhuri 《应用有机金属化学》2009,23(12):527-534
A mononuclear copper (II) complex of N‐2‐hydroxyhippuric acid (2HHA), [Cu(HA)(H2O)2], has been synthesized and characterized by spectroscopic and X‐ray powder diffraction studies. Crystal structure of [Cu(HA)(H2O)2] reveals a distorted square‐pyramidal geometry around the metal center. The crystal packing in the complex exhibits a three‐dimensional framework formed by intermolecular O? ; H···O and C? H···O hydrogen bonds. Toxicity and antitumor properties of the complex have been studied in vivo. The complex, capable of depleting glutathione (GSH) at nontoxic doses, may be utilized to sensitize drug‐resistant cells where resistance is due to an elevated level of GSH. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
109.
Chanchal Das Tanushree Chakraborty Soumen Ghosh Bijan Das 《Colloid and polymer science》2008,286(10):1143-1155
Mixed micellization of binary and ternary mixtures of anionic and nonionic surfactants, such as lithium dodecyl sulfate, polyoxyethylene(23)laurylether,
and polyoxyethylene-tert-octylphenylether, is studied in aqueous solution using tensiometric, conductometric, and spectrophotometric methods. Although
tensiometry and conductometry complement each other closely, the spectroscopic critical micellar concentration (cmc) is far
from agreement with tensiometric study. Several parameters, e.g., cmc, degree of counterion binding, free energies of micellization,
and interfacial adsorption, have been evaluated. Established theories of Clint, Rosen, Rubingh, Motomura, Georgiev, Maeda,
and Blankschtein were applied to evaluate the mole fraction of different components in the self-aggregated phase, the interaction
parameter, free energy contributions, and expected cmc. 相似文献
110.
A stereoselective synthesis of the C1-C15 fragment of a G-actin binding natural macrodiolide, rhizopodin was achieved using, as key steps, highly stereoselective acetate aldol reactions to build the C1-C7 fragment, one pot oxazole synthesis and an asymmetric Keck allylation reaction to build the C8-C15 fragment and finally, a Stille reaction to couple both the fragments. 相似文献