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631.
Lyocell is a type of regenerated cellulose. Fibres spun from cellulose solution in N-methylmorpholine-N-oxide hydrate consist of crystalline cellulose II and amorphous cellulose. Lyocell fabrics were treated with aqueous sodium hydroxide solution (NaOH) to study the influence of alkali on optical and structural properties. It was observed that sodium hydroxide treatment causes the density, orientation and crystallinity of lyocell fibre to decrease with increasing sodium hydroxide concentration, a corresponding decrease in tensile strength is also observed. The greatest change in fibre properties occurs between 3.0 and 5.0 mol dm−3 NaOH. This is attributed to the onset of formation of Na-cellulose II at 3.0 mol dm−3 NaOH; a fully formed Na-cellulose II structure is expected above 6.8 mol dm−3 NaOH. Formation of Na-cellulose II causes plasticization of the lyocell fibres as both inter- and intra-molecular hydrogen bonds are broken by these higher sodium hydroxide concentrations. 相似文献
632.
Manashi Panda Chayan Das Chen-Hsiung Hung Sreebrata Goswami 《Journal of Chemical Sciences》2007,119(1):3-9
Reactions of IrCl3·xH2O with the ligands, 2-[(phenylamino)phenylazo]pyridine (HL1a) and 2-[(p-tolylamino)phenylazo]pyridine (HL1b) produce [Ir(L1)2]Cl (L1 = L1a, [1]Cl and L1 = L1b, [2]Cl) along with many unidentified products. The iridium complexes have been characterized by various techniques such as X-ray
crystallography, mass spectrometry, 1H and 13C NMR, cyclic voltammetry and absorption studies. The complex [1]ClO4 crystallises in triclinic space group. The crystallographic data have been determined. Notably, the Ir-N (azo) lengths are
short (av. 1·9875(4) ?) as compared to the remaining four Ir-N lengths (av. 2·052(5) ?). There is significant degree of ligand
backbone conjugation in the coordinated ligands, which result in shortening of the C-N lengths on the other side of the middle
phenyl ring and also in lengthening of the diazo (N=N) lengths. The complexes display multiple low energy transitions ranging
between 1010 and 450 nm. These are electro active and show three reversible redox responses in the potential range, +1·5 V
to −1·5 V. The cathodic potential responses are ascribed as ligand reductions, while the redox process at the anodic potential
occurs at a mixed metal-ligand (HOMO) orbital. 相似文献
633.
Mrinal Sinha M. Maitra Goswami D. Mal T. R. Middya S. Tarafdar Udayan De Sandip Kumar Chaudhuri D. Das 《Ionics》2008,14(4):323-327
Irradiation affects the structures of materials at different scales, thus changing physical and chemical properties. We study
here the effect of gamma irradiation at different doses on the polymer electrolyte PEO-NH4ClO4. Optical micrographs show cracks in the irradiated samples and impedance spectroscopy measurements indicate reduced ion-conductivity
at room temperature but slight enhancement at higher temperature. At high frequencies, the real part of the admittance shows
a power-law variation; the exponent, which is a measure of self-similarity of the structure, is reduced on irradiation. The
overall results point to a more disordered structure at higher radiation doses. 相似文献
634.
635.
This paper analyzes a finite-buffer multiserver bulk-service queueing system in which the interarrival and service times are, respectively, arbitrarily and exponentially distributed. Using the supplementary variable and the imbedded Markov chain techniques, we obtain the queue-length distributions at prearrival and arbitrary epochs. We also present Laplace–Stiltjes transform of the actual waiting-time distribution in the queue. Finally, several performance measures and a variety of numerical results in the form of tables and graphs are discussed. 相似文献
636.
We investigate the Peres–Horodecki positive partial transpose criterion in the context of conserved quantities and derive a condition of inseparability for a composite bipartite system depending only on the dimensions of its subsystems, which leads to a bi-linear entanglement witness for the two qubit system. A separability inequality using generalized Schrodinger–Robertson uncertainty relation taking suitable operators, has been derived, which proves to be stronger than the bi-linear entanglement witness operator. In the case of mixed density matrices, it identically distinguishes the separable and non separable Werner states. 相似文献
637.
The present work deals with the behavior of fiber bundle model under heterogeneous loading condition. The model is explored both in the mean-field limit as well as with local stress concentration. In the mean field limit, the failure abruptness decreases with increasing order k of heterogeneous loading. In this limit, a brittle to quasi-brittle transition is observed at a particular strength of disorder which changes with k. On the other hand, the model is hardly affected by such heterogeneity in the limit where local stress concentration plays a crucial role. The continuous limit of the heterogeneous loading is also studied and discussed in this paper. Some of the important results related to fiber bundle model are reviewed and their responses to our new scheme of heterogeneous loading are studied in details. Our findings are universal with respect to the nature of the threshold distribution adopted to assign strength to an individual fiber. 相似文献
638.
Dipak Kumar Das Sk Imadul Islam Nirnay Samanta Yogendra Yadav Debabrata Goswami Rajib Kumar Mitra 《Journal of fluorescence》2018,28(3):855-862
Rhodamine group of molecules are widely used dyes for imaging of biological molecules. Application of these dyes however includes a limitation that these molecules absorb in the visible range of the spectrum, which does not fall in the ‘biologically transparent window’ (BTW). Two photon absorption (TPA) process could come up with an alternate solution to this as these dyes could be excited in the near infrared (NIR) window to extract similar information. To validate this we have investigated TPA cross section (TPACS, σ2) of two rhodamine dyes, namely Rhodamine 6G (R6G), Rhodamine B (RhB), site selectively bound with a model protein, bovine serum albumin (BSA), by exciting at 800 nm. Two photon spectroscopy and imaging confirms the binding of the dye to the protein. The decreases in TPACS with increasing temperature at a fixed BSA concentration excellently follows the temperature induced structural transition of BSA as the protein transforms from a molten globule to unfolded conformation beyond 60 °C, which has previously been established through circular dichroism (CD) measurements. The thus established resemblance in TPACS and CD measurement trends thus strongly affirms the suitability of TPA process in protein imaging and as an alternative marker to tracking its conformational transformations using NIR radiation. 相似文献
639.
Chirantan Gayen Upashi Goswami Kasturi Gogoi Srestha Basu Anumita Paul 《Chemphyschem》2019,20(7):953-958
Herein, we report the construction of intracellular logic operations using luminescent histidine stabilized gold nanoclusters (His Au NCs). The luminescence intensity of His Au NCs was found to be significantly enhanced following interaction with zinc ions, owing to “Crystallization induced emission enhancement”. Further, the luminescence intensity of His Au NCs was found to be effectively quenched in presence of sulphide ions, owing to transformation of emissive His Au NCs to non-emissive gold nanoparticles. Thus, the collective and individual effects of zinc ions and sulphide ions causing significant variation in the luminescence intensity of His Au NCs, were used as input parameters for construction of intracellular logic operations such as Tri state buffer, “on-off” switch and INHIBIT gate within mammalian cells. 相似文献
640.
Datta Arghya Gupta Raj Kumar Goswami Sunil Sharma Vijay Kumar Bhunia Haripada Singh Damandeep Pant Harish Jagat 《Journal of Radioanalytical and Nuclear Chemistry》2019,320(3):711-723
Journal of Radioanalytical and Nuclear Chemistry - In the present study, residence time distribution measurements were carried out in an industrial-scale ethyl acetate reactors using Bromine-82 as... 相似文献