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Condensation of 2-hydroxyacetophenones 1 with cinnamic anhydrides 2 in the presence of tetra-n-butyl ammonium hydrogen sulphate in benzene-aqueous potassium carbonate biphase medium give 1-(2-hydrcxyphenyl)-5-phenyl-4-pentene-l, 3-diones 3 which on cyclodehydration using p-toluene sulphonic acid in dimethylsulphoxide give 2-styrylchromones 4 in high yields. 相似文献
3.
In order to study the droplet pattern and electro-optic (EO) behaviour of polymer dispersed liquid crystal (PDLC) with the addition of dye, dichroic polymer dispersed liquid crystal (DPDLC) films were prepared using a nematic liquid crystal (NLC), photo-curable polymer (NOA 65) and anthraquinone blue dichroic dye (B2), in equal ratio (1:1) of polymer and liquid crystal (LC) by polymerisation induced phase separation (PIPS) technique. Dichroic dye was taken in different concentration (wt./wt. ratio) as 0.0625%, 0.125%, 0.25%, 0.5% and 1% of the LC mixture in DPDLC films. Initially, in an open circuit when there is no proviso for external electric field (0 V), LC droplets in polymer matrix exhibited bipolar pattern, though on closing the circuit with the increase of electric field pattern of droplets starts changing, LC molecules align along the direction of applied electric field and aligned completely relatively at higher field (30 V), which illustrate vertical radial pattern. Further, results show that the DPDLC film containing 0.0625% dye concentration with consistent average droplet size ~4.30 μm, exhibits the best transmission at lower operating voltage. 相似文献
4.
Mulholland AJ O'Leary RL Ramadas N Parr A Troge A Pethrick RA Hayward G 《Ultrasonics》2007,47(1-4):102-110
This paper investigates the use of magnetically active materials in the matching layer of a piezoelectric transducer. This then allows the performance of the device to be dynamically altered by applying an external field. The effect that this new matching layer has on the performance of a typical device is theoretically investigated here. It transpires that the additional flexibility of an active matching layer can be used to maintain the efficiency of the device as the external load is varied. 相似文献
5.
Preeti Jain Vandna Singh Sabir Ali Vishwas Tripathi Upendra Saraswat 《Journal of Saudi Chemical Society》2018,22(5):546-557
Macrocyclic Schiff base ligand through the condensation of 1,3-dicarbonyl-phenyl-dihydrazide with 4,4′-difluorobenzil and its Co(II), Ni(II), Cu(II) and Zn(II) metal complexes have been synthesized. The ligand and metal complexes were characterized by analytical and physicochemical methods. An octahedral geometry arising from coordination of N2O2 donor atoms from the macrocyclic framework has been proposed for all metal complexes. Synthesized ligand and metal complexes were investigated for in vitro antibacterial and antioxidant activity. Complex [Ni(C22H14N4F2O2)(OCOCH3)2] has shown remarkable antibacterial activity (Minimum inhibitory concentration 8–16?μg/ml) comparable to commercial antibiotic Ciprofloxacin. Anticancer activity of synthesized compounds against Squamous Cell Carcinoma (SCC4), head and neck cancer cell line has also been studied at different concentrations and at different time points. Complexes [Co(C22H14N4F2O2)(NO3)2] and [Cu(C22H14N4F2O2)(OCOCH3)2] have shown remarkable anticancer results (IC50 31.1 and 43.1?μM) against the tested cell line in concentration dependent manner. Molecular docking studies were carried out to find the binding mode of the synthesized macrocyclic Schiff base ligand to Epidermal Growth Factor Receptor (EGFR) Kinase (PDB ID: 1M17). 相似文献
6.
It is well known that the likelihood inferences in dynamic mixed models for count data is extremely complicated. In this paper, we, first, develop a generalized method of moments (GMM) approach for the estimation of the parameters of such models. We then consider an alternative generalized quasi-likelihood (GQL) approach. The relative efficiency of the GQL approach to the GMM approach is examined by comparing the asymptotic variances of the GQL estimates of the parameters to the corresponding asymptotic variances of the GMM estimates. 相似文献
7.
Quadrature spatial modulation (QSM) utilizes the in‐phase and quadrature spatial dimensions to transmit the real and imaginary parts of a single signal symbol, respectively. The improved QSM (IQSM) transmits two signal symbols per channel use through a combination of two antennas for each of the real and imaginary parts. The main contributions of this study can be summarized as follows. First, we derive an upper bound for the error performance of the IQSM. We then design constellation sets that minimize the error performance of the IQSM for several system configurations. Second, we propose a double QSM (DQSM) that transmits the real and imaginary parts of two signal symbols through any available transmit antennas. Finally, we propose a parallel IQSM (PIQSM) that splits the antenna set into equal subsets and performs IQSM within each subset using the same two signal symbols. Simulation results demonstrate that the proposed constellations significantly outperform conventional constellations. Additionally, DQSM and PIQSM provide a performance similar to that of IQSM while requiring a smaller number of transmit antennas and outperform IQSM with the same number of transmit antennas. 相似文献
8.
Jian Liu Mariavittoria Craighero Vandna K. Gupta Dorothea Scheunemann Sri Harish Kumar Paleti Emmy Järsvall Youngseok Kim Kai Xu Juan Sebastián Reparaz L. Jan Anton Koster Mariano Campoy-Quiles Martijn Kemerink Anna Martinelli Christian Müller 《Advanced functional materials》2024,34(18):2312549
Functionally graded materials (FGMs) are widely explored in the context of inorganic thermoelectrics, but not yet in organic thermoelectrics. Here, the impact of doping gradients on the thermoelectric properties of a chemically doped conjugated polymer is studied. The in-plane drift of counterions in moderate electric fields is used to create lateral doping gradients in films composed of a polythiophene with oligoether side chains, doped with 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4TCNQ). Raman microscopy reveals that a bias voltage of as little as 5 V across a 50 µm wide channel is sufficient to trigger counterion drift, resulting in doping gradients. The effective electrical conductivity of the graded channel decreases with bias voltage, while an overall increase in Seebeck coefficient is observed, yielding an up to eight-fold enhancement in power factor. Kinetic Monte Carlo simulations of graded films explain the increase in power factor in terms of a roll-off of the Seebeck coefficient at high electrical conductivities in combination with a mobility decay due to increased Coulomb scattering at high dopant concentrations. Therefore, the FGM concept is found to be a way to improve the thermoelectric performance of not yet optimally doped organic semiconductors, which may ease the screening of new materials as well as the fabrication of devices. 相似文献
9.
Bhattacharya M Jain N Bhasne K Kumari V Mukhopadhyay S 《Journal of fluorescence》2011,21(3):1083-1090
Serum albumins are multi-domain all α-helical proteins that are present in the circulatory system and aid in the transport
of a variety of metabolites, endogenous ligands, drugs etc. Earlier observations have indicated that serum albumins adopt
a range of reversible conformational isomers depending on the pH of the solution. Herein, we report the concurrent changes
in the protein conformation and size that are inherent to the pH-induced conformational isomers of bovine serum albumin (BSA).
We have investigated the fluorescence properties of both intrinsic (tryptophan) and extrinsic (ANS, pyrene) fluorophores to
shed light into the structural features of the pH-dependent conformers. We have been able to identify a number of conformational
isomers using multiple fluorescence observables as a function of pH titration. Our results indicate that at pH 3, a partially-folded,
‘molten-globule-like’ state is populated. Moreover, equilibrium unfolding studies indicated that the ‘molten-globule-like’
state unfolds in a non-cooperative fashion and is thermodynamically less stable than the native state. The fluorescence-based
approach described in the present work has implications in the study of pH-induced conformational plasticity of other physiologically
relevant proteins. 相似文献
10.
D.?P.?SinghEmail author Ramesh?Kumar Vandna?Malik Parikshit?Tyagi 《Transition Metal Chemistry》2007,32(8):1051-1055
A new series of complexes is synthesized by template condensation of glyoxal and oxalyldihydrazide in methanolic medium in
the presence of divalent cobalt, nickel, copper, zinc and cadmium salts forming complexes of the type: [M(C8H8N8O4)X2] where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and X = Cl−1, Br−1, NO
3
−1
, OAc−1. The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility
measurements, electronic, n.m.r., infrared and far infrared spectral studies. On the basis of these studies, a six coordinate
octahedral geometry for these complexes has been proposed. The biological activities of the metal complexes have been tested
in vitro against a number of pathogenic bacteria to assess their inhibiting potential. Most of the compounds have been found to exhibit
remarkable antibacterial activities. 相似文献