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21.
Three copper(ii) complexes with bidentate ligands L(1), L(2) and L(3) [L(1), N,N(/)-dimethylethylenediamine; L(2), N,N(/)-diethylethylenediamine and L(3), N,N(/)-diisobutylethylenediamine], respectively, were synthesized as their perchlorate salts. The single crystal structures for all the complexes were determined. The nitric oxide reactivity of the complexes was studied in acetonitrile solvent. The formation of thermally unstable [Cu(II)-NO] intermediate on reaction of the complexes with nitric oxide in acetonitrile solution was observed prior to the reduction of copper(II) centres to copper(I). The reduction was found to result with a simultaneous mono- and di-nitrosation at the secondary amine sites of the ligand. All the nitrosation products were isolated and characterized. The ratio of the yield of mono- and di-nitrosation product was found to be dependent on the N-substitution present in the ligand framework. 相似文献
22.
Series of compositions Bi2(M′xM1−x)4O9 with x=0.0, 0.1,…, 1.0 and M′/M=Ga/Al, Fe/Al and Fe/Ga were synthesized by dissolving appropriate amounts of corresponding metal nitrate hydrates in glycerine, followed by gelation, calcination and final heating at 800 °C for 24 h. The new compositions with M′/M=Ga/Al form solid-solution series, which are isotypes to the two other series M′/M=Fe/Al and Fe/Ga. The XRD data analysis yielded in all cases a linear dependence of the lattice parameters related on x. Rietveld structure refinements of the XRD patterns of the new compounds, Bi2(GaxAl1−x)4O9 reveal a preferential occupation of Ga in tetrahedral site (4 h). The IR absorption spectra measured between 50 and 4000 cm−1 of all systems show systematic shifts in peak positions related to the degree of substitution. Samples treated in 18O2 atmosphere (16 h at 800 °C, 200 mbar, 95% 18O2) for 18O/16O isotope exchange experiments show a well-separated IR absorption peak related to the M-18Oc-M vibration, where Oc denotes the common oxygen of two tetrahedral type MO4 units. The intensity ratio of M-18Oc/M-16Oc IR absorption peaks and the average crystal sizes were used to estimate the tracer diffusion coefficients of polycrystalline Bi2Al4O9 (D=2×10−22 m2s−1), Bi2Fe4O9 (D=5×10−21 m2s−1), Bi2(Ga/Al)4O9 (D=2×10−21 m2s−1) and Bi2Ga4O9 (D=2×10−20 m2s−1). 相似文献
23.
The mixing of the glueball candidate?i(1,460) with η and η′ is studied in a chiral symmetry breaking framework. Using the solutions of anomalous Ward identities for flavourU(3)×U(3), we find that the octet-singlet mixing angle is quite large and that our results are consistent with a large glueball component in?i(1,460) with moderate gluonium mixing in η and η′. 相似文献
24.
Mitali Banerjee A.K. Majumdar Biplab Sanyal 《Journal of magnetism and magnetic materials》2010,322(21):3558-3564
We report here an experimental study of magnetization of FeNiW alloys at different compositions. We have studied variation of magnetization with temperature (at low external fields) and magnetic field (at low temperatures). The alloy shows para to ferromagnetic transitions across the composition range. We do not find any indication of the spin-glass phase. We have supplemented the experimental work with theoretical analysis using the first-principles tight-binding linear muffin-tin orbitals based augmented space recursion method. Our theoretical estimates of magnetic moment and Curie temperatures agree well with experiment. Our mean-field phase analysis also does not indicate the possibility of a spin-glass phase. 相似文献
25.
On the basis of a special cone and the application of the fixed point theory, some new results for the existence of positive solutions of singular Sturm–Liouville boundary value problems on the half-line are obtained. 相似文献
26.
Rajiv Karmakar Asim Bhaumik Biplab Banerjee Chhanda Mukhopadhyay 《Tetrahedron letters》2017,58(7):622-628
An enhanced one-pot synthesis of new functionalized 5,6-dihydro-5,5-dimethyl-2-phenyl-2H-pyridazino[3,4,5-kl]acridin-1(4H)-one derivatives with different substituted patterns by using mesoporous MCM-41 catalyst via a ring opening/ring closure reaction process has been established. This MCM-41 silica catalyst has been synthesized and characterized using an array of sophisticated analytical techniques like BET, XRD, UHRTEM, etc. This reaction could be conducted from inexpensive substrates within short period under neat reflux conditions. Compared with the usual methods, the remarkable advantages of this method are milder reaction conditions, operational simplicity, higher yields, short reaction times and an environmentally friendly procedure. 相似文献
27.
Asim Debnath 《Liquid crystals》2017,44(14-15):2192-2202
Four multicomponent room temperature mixtures were formulated using a pyrimidine-based achiral matrix as host and four terphenyl-based ester chiral compounds as dopants. Among the four mixtures, two exhibit antiferroelectric and two other exhibit ferroelectric phases at room temperature. Dopant molecules differ from each other by position and number of fluorine atom substitution at the benzoate group of the molecular rigid core. Number and location of fluorine atoms in the dopant structure show significant effect on the phase sequences as well as on different physical properties. All the mixtures found to have moderate spontaneous polarisation, high tilt angle, very fast switching time and low viscosity which are important for liquid crystal-based display applications. 相似文献
28.
Dibyendu Das Sangita Roy Sisir Debnath Prasanta Kumar Das Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(16):4911-4922
Hydrogels of amino acid based cationic surfactant having C16 tails were used to immobilize heme proteins and enzyme. These hydrogel‐entrapped proteins/enzyme showed remarkable activation when dispersed in organic solvent. The activation effect (ratio of the activity of the hydrogel‐entrapped enzyme in organic solvent to the activity of the native enzyme in water) of cytochrome c increased up to 350‐fold with varying protein and gelator concentration. Hydrogel‐entrapped hemoglobin and horseradish peroxidase (HRP) also showed markedly improved activity in organic solvent. Alteration in the structure of the gelator and its supramolecular arrangement showed that the protein immobilized within amphiphilic networks with larger interstitial space exhibited higher activation. This striking activation of hydrogel‐entrapped proteins stems from the following effects: 1) the hydrophilic domain of the amphiphilic networks facilitates accessibility of the enzyme to the water‐soluble substrate. 2) the surfactant, as an integral part of the amphiphilic network, assists in the formation of a distinct interface through which reactants and products are easily transferred between hydrophilic and hydrophobic domains. 3) Surfactant gelators help in the dispersion and stabilization of gel matrix into small particles in organic solvent, which enhances the overall surface area and results in improved mass transfer. The activation was dramatically improved up to 675‐fold in the presence of nongelating anionic surfactants that helped in disintegration of the gel into further smaller‐sized particles. Interestingly, hydrogel‐immobilized HRP exhibited about 2000‐fold higher activity in comparison to the activity of the suspended enzyme in toluene. Structural changes of the entrapped enzyme and the morphology of the matrix were investigated to understand the mechanism of this activation. 相似文献
29.
A series of tungsten-tellurite glasses activated with different concentrations (0–1.5 mol %) of Er3+ has been synthesized. The structural properties of the best luminescent sample and the optical properties of its Er3+ ions, are studied both immediate after its preparation as well as after its ageing. On ageing the glass suffers structural
reorganization and generates Er2WO6—nanocrystals in the matrix, which greatly enhances the normal and upconversion green luminescence efficiency of Er3+. The nanocrystal aided enhancement of normal and upconversion luminescence of Er3+ of the glass has been attributed to the crystal field effects of the new environment of Er3+ in the nanocrystals. A phenomenon of preferential enhancement of red upconversion luminescence at the cost of green upconversion
luminescence of Er3+ at its higher concentrations in the glass has been observed and the related photo-physics is proposed. The material shows
the prospect of being used as NIR solar concentrator. 相似文献
30.
We have considered a model of two component mixture i.e., mixture of Chaplygin gas and barotropic fluid with tachyonic field.
In the case, when they have no interaction then both of them retain their own properties. Let us consider an energy flow between
barotropic and tachyonic fluids. In both the cases we find the exact solutions for the tachyonic field and the tachyonic potential
and show that the tachyonic potential follows the asymptotic behavior. We have considered an interaction between these two
fluids by introducing a coupling term. Finally, we have considered a model of three component mixture i.e., mixture of tachyonic
field, Chaplygin gas and barotropic fluid with or without interaction. The coupling functions decays with time indicating
a strong energy flow at the initial period and weak stable interaction at later stage. To keep the observational support of
recent acceleration we have considered two particular forms (i) Logamediate Scenario and (ii) Intermediate Scenario, of evolution
of the Universe. We have examined the natures of the recent developed statefinder parameters and slow-roll parameters in both
scenarios with and without interactions in whole evolution of the universe. 相似文献