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21.
Roy Ramkrishna Bag Kanchan Santra Prasanta Kumar Sinha Chittaranjan 《Transition Metal Chemistry》2000,25(3):302-305
Binuclear chloro-bridged cyclopalladated azobenzenes [Pd(A)Cl]2 (A = ortho-metallated azobenzene or its derivatives) have been reacted with aqueous AgNO3 to yield aquo-derivatives followed by the addition of xanthates, or dithiocarbamates (RCS2
–) to synthesise ternary complexes, [Pd(A)(RCS2)]. These complexes occur as configurational isomers and their compositions have been established by 1H-n.m.r. spectroscopy. Cyclic voltammetric studies show azo reduction at negative and thiol oxidation at positive potentials relative to s.c.e., respectively. Dissociation of RCS2
– under the electrode field is chemically supported by using a sulfide extractor, HgCl2, Hg(OAc)2, or AgOAc, to precipitate out the binuclear [Pd(A)Cl]2/[Pd(A)(OAc)]2 complexes. 相似文献
22.
Kanchan Verma Yogesh Kumar Tailor Sarita Khandelwal Monu Agarwal Esha Rushell Sakshi Pathak Yogita Kumari Kamlendra Awasthi Mahendra Kumar 《应用有机金属化学》2020,34(10):e5836
An efficient and environmentally sustainable domino protocol has been presented for the synthesis of structurally diverse spiroannulated indolo[3,2-c]quinolines involving three component sequential reaction of phenylhydrazine, o-aminoacetophenone and cyclic ketones using nanostructured terbium doped TiO2 as recyclable and reusable heterogeneous catalyst. The nanostructured catalyst was synthesized successfully and characterized by X-ray Diffraction (XRD), transmission electron microscopy (TEM), EDX and Fourier transform infra-red spectroscopy (FTIR). The substitution of Ti+4 with Tb+3 and the formation of Ti-O-Tb bonds as a result of doping of Terbium with TiO2 NPs increases the catalytic efficiency and facilitates the reaction to provide the products in excellent yields. The present protocol with special features; operational simplicity, atom-economy, mild reaction conditions, environmental sustainability and high synthetic efficiency with recyclability and reusability of catalyst has been reported for the first time to synthesize spiroannulated indoloquinolines and expecting to provide the library of promising new leads in drug discovery research. 相似文献
23.
Kanchan Ghosal Rey T. Chern Benny D. Freeman Raj Savariar 《Journal of Polymer Science.Polymer Physics》1995,33(4):657-666
CO2, CH4, O2, and N2 permeability and solubility of unmodified and aryl-nitrated polysulfone were determined at 35°C and pressures up to 20 atm. The degree of nitration was varied from 0 to 2 nitro groups per repeat unit. The permeability and diffusion coefficients for all gases decreased with increasing degree of nitro substitution. The decrease in gas diffusivity is attributed to a combination of decreased fractional free volume and decreased torsional mobility with increasing degree of substitution. The solubilities of N2, O2, and CH4 do not show a systematic dependence on degree of substitution. However, CO2 solubility apparently goes through a minimum as the degree of substitution is increased. CO2 solubility may be influenced by a competition between increases in polymer polarity (favoring higher solubility) and lower free volume (favoring lower solubility) that accompanies increases in the polar nitro substituent concentration. CO2/CH4 solubility selectivity increases monotonically as the degree of substitution increases. CO2/CH4 permselectivity and diffusivity selectivity increased with increasing degree of substitution. © 1995 John Wiley & Sons, Inc. 相似文献
24.
S. N. Lahiri Kanchan Mukherjee 《Annals of the Institute of Statistical Mathematics》2004,56(2):225-250
In this paper, we consider M-estimators of the regression parameter in a spatial multiple linear regression model. We establish
consistency and asymptotic normality of the M-estimators when the data-sites are generated by a class of deterministic as
well as a class of stochastic spatial sampling schemes. Under the deterministic sampling schemes, the data-sites are located
on a regular grid but may have aninfill component. On the other hand, under the stochastic sampling schemes, locations of the data-sites are given by the realizations
of a collection of independent random vectors and thus, are irregularly spaced. It is shown that scaling constants of different
orders are needed for asymptotic normality under different spatial sampling schemes considered here. Further, in the stochastic
case, the asymptotic covariance matrix is shown to depend on the spatial sampling density associated with the stochastic design.
Results are established for M-estimators corresponding to certain non-smooth score functions including Huber’s ψ-function
and the sign functions (corresponding to the sample quantiles).
Research of Lahiri is partially supported by NSF grant no. DMS-0072571. Research of Mukherjee is partially supported by the
Academic Research Grant R-155-000-003-112 from the National University of Singapore. 相似文献
25.
Hypochlorite‐Mediated Modulation of Photoinduced Electron Transfer in a Phenothiazine–Boron dipyrromethene Electron Donor–Acceptor Dyad: A Highly Water Soluble “Turn‐On” Fluorescent Probe for Hypochlorite
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Disha Soni Naresh Duvva Deepak Badgurjar Dr. Tapta Kanchan Roy Dr. Surendra Nimesh Geeta Arya Dr. Lingamallu Giribabu Dr. Raghu Chitta 《化学:亚洲杂志》2018,13(12):1594-1608
A highly water‐soluble phenothiazine (PTZ)–boron dipyrromethene (BODIPY)‐based electron donor–acceptor dyad ( WS‐Probe ), which contains BODIPY as the signaling antennae and PTZ as the OCl? reactive group, was designed and used as a fluorescent chemosensor for the detection of OCl?. Upon addition of incremental amounts of NaOCl, the quenched fluorescence of WS‐Probe was enhanced drastically, which indicated the inhibition of reductive photoinduced electron transfer (PET) from PTZ to 1BODIPY*; the detection limit was calculated to be 26.7 nm . Selectivity studies with various reactive oxygen species, cations, and anions revealed that WS‐Probe was able to detect OCl? selectively. Steady‐state fluorescence studies performed at varied pH suggested that WS‐Probe can detect NaOCl and exhibits maximum fluorescence in the pH range of 7 to 8, similar to physiological conditions. ESI‐MS analysis and 1H NMR spectroscopy titrations showed the formation of sulfoxide as the major oxidized product upon addition of hypochlorite. More interestingly, when WS‐Probe was treated with real water samples, the fluorescence response was clearly visible with tap water and disinfectant, which indicated the presence of OCl? in these samples. The in vitro cell viability assay performed with human embryonic kidney 293 (HEK 293) cells suggested that WS‐probe is non‐toxic up to 10 μm and implicates the use of the probe for biological applications. 相似文献
26.
Amita Verma Kanchan Saxena Chanderkant S. K. Dhawan R. K. Sharma C. P. Sharma M. N. Kamalasanan S. Chandra 《Applied biochemistry and biotechnology》2001,96(1-3):215-223
Poly-p-phenylenes have attracted a great deal of attention with respect to their applications in displays, light-emitting devices,
and batteries. However, the polymer poly-p-phenylene obtained by the Kovacic method is insoluble and intractable. The present study reports the preparation of soluble
poly(p-phenylenes) by polymerization of derivatives of benzene in the presence of a specific aromatic nuclei. The resultant copolymer
so obtained is soluble in common organic solvents such as chloroform and toluene. Preliminary studies have indicated that
the polymer shows orange photoluminescence and electroluminescence when a potential of 7–10 V is applied to the device. 相似文献
27.
28.
Summary This paper establishes the uniform closeness of a weighted residual empirical process to its natural estimate in the linear regression setting when the errors are Gaussian, or a function of Gaussian random variables, that are strictly stationary and long range dependent. This result is used to yield the asymptotic uniform linearity of a class of rank statistics in linear regression models with long range dependent errors. The latter result, in turn, yields the asymptotic distribution of the Jaeckel (1972) rank estimators. The paper also studies the least absolute deviation and a class of certain minimum distance estimators of regression parameters and the kernel type density estimators of the marginal error density when the errors are long range dependent.Research of this author was partly supported by the NSF grant: DMS-9102041 相似文献
29.
This paper describes an effect of flow rate, carrier gas (H2, N2 and Ar) composition, and amount of benzene on the quality and the yield of carbon nanotubes (CNTs) formed by catalytical
vapour dcomposition (CVD) method. The flow and mass control of gases and precursor vapors respectively were found to be interdependent
and therefore crucial in deciding the quality and yield of CNTs. We have achieved this by modified soap bubble flowmeter,
which controlled the flow rates of two gases, simultaneously. With the help of this set-up, CNTs could be prepared in any
common laboratory. Raman spectroscopy indicated the possibilities of formation of single-walled carbon nanotubes (SWNTs).
From scanning electron microscopy (SEM) measurements, an average diameter of the tube/bundle was estimated to be about 70
nm. The elemental analysis using energy dispersion spectrum (EDS) suggested 96 at.wt.% carbon along with ca. 4 at.wt.% iron
in the as-prepared sample. Maximum yield and best quality CNTs were obtained using H2 as the carrier gas.
相似文献
30.
S. Verma J. J. Das A. Jhingan K. Kalita S. Barua K. S. Golda N. Madhavan P. Sugathan S. Nath T. Varughese J. Gehlot S. Mandal S. Ranjit P. K. Sahu B. John B. K. Nayak A. Saxena S. K. Datta R. Singh 《The European physical journal. Special topics》2007,150(1):75-78
Elastic scattering angular distributions have been measured for 7Be + 9Be system at Elab = 17, 19 and 21 MeV in the angular range θcm=26○–58°, and for 7Li + 9Be system at Elab= 15.75, 24 and 30 MeV.
An optical model (OM) analysis of these data have been carried out.
For the 7Li + 9Be system fusion cross sections were obtained at Elab = 15.75, 24 and 30 MeV by measuring the α-evaporation spectra from the compound nucleus at backward angles. The measured
α-evaporation spectra were reproduced by the statistical model calculations and fusion cross sections were extracted therefrom.
The ratios of the experimental fusion cross sections to the total reaction cross sections (obtained form OM analysis) were
found to be rather small. This result suggests that break-up process has a strong influence on fusion process leading to a
reduction in fusion cross section. 相似文献