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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
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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
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Radiofluorination of a Pre‐formed Gallium(III) Aza‐macrocyclic Complex: Towards Next‐Generation Positron Emission Tomography (PET) Imaging Agents
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Dr. Rajiv Bhalla Prof. William Levason Dr. Sajinder K. Luthra Dr. Graeme McRobbie George Sanderson Prof. Gillian Reid 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4688-4694
As part of a study to investigate the factors influencing the development of new, more effective metal‐complex‐based positron emission tomography (PET) imaging agents, the distorted octahedral complex, [GaCl(L)]?2 H2O has been prepared by reaction of 1‐benzyl‐1,4,7‐triazacyclononane‐4,7‐dicarboxylic acid hydrochloride (H2L?HCl) with Ga(NO3)3?9 H2O, which is a convenient source of GaIII for reactions in water. Spectroscopic and crystallographic data for [GaCl(L)]?2 H2O are described, together with the crystal structure of [GaCl(L)]?MeCN. Fluorination of this complex by Cl?/F? exchange was achieved in high yield by treatment with KF in water at room temperature over 90 minutes, although the reaction was complete in approximately 30 minutes if heated to 80 °C, giving [GaF(L)]?2 H2O in good yield. The same complex was obtained by hydrothermal synthesis from GaF3?3 H2O and Li2L, and has been characterised by single‐crystal X‐ray analysis, IR, 1H and 19F{1H} NMR spectroscopy and ESI+ MS. Radiofluorination of the pre‐formed [GaCl(L)]?2 H2O has been demonstrated on a 210 nanomolar scale in aqueous NaOAc at pH 4 by using carrier‐free 18F?, leading to 60–70 % 18F‐incorporation after heating to 80 °C for 30 minutes. The resulting radioproduct was purified easily by using a solid‐phase extraction (SPE) cartridge, leading to 98–99 % radiochemical purity. The [Ga18F(L)] is stable for at least 90 minutes in 10 % EtOH/NaOAc solution at pH 6, but defluorinates over this time scale at pH of approximately 7.5 in phosphate buffered saline (PBS) or human serum albumin (HSA). The subtle role of the Group 13 metal ion and co‐ligand donor set in influencing the pH dependence of this system is discussed in the context of developing potential new imaging agents for PET. 相似文献
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L K Misra M G Luthra S R Amtey G Elizondo-Riojas S H Swezey L E Todd 《Magnetic resonance imaging》1984,2(1):33-35
Proton spin-lattice relaxation times (T1) of pectoralis major muscles from normal (Line 412) and homozygous dystrophic (Line 413) chicks was measured by FONAR QED 80 at 1.69 MHz. The T1 values of dystrophic muscles (216.8 +/- 17.3 ms) was two-fold higher than those of normal muscles (110.2 +/- 8.1 msec). When these values were compared with the T1 values obtained at high frequencies (20 MHz and 32 MHz), the T1 differentiation between normal and dystrophic muscles was considerably enhanced at 1.69 MHz. Based on these results, we suggest that the high resolution of T1 obtained at low frequency (1.69 MHz) could be effectively used to detect the degenerative processes in muscles by the NMR techniques. 相似文献
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Thermoluminescence glow curves are a fairly good representation of the different defect centres in MgO produced by γ or reactor irradiation. The glow peaks at 370, 440, 485 and 545 K have been found to be due to hole trapped centres. The 370 K peak has been found to be due to holes released from VM centres (hole trapped at action vacancy associated with a neighbouring impurity ion). The 665 K peak in γ-irradiated MgO is due to charge transfer between the adsobred oxygen ions and surface defect centres. The F-type centres produced on reactor irradiation (neutron and γ) and on quenching from high temperatures before γ-irradiation are also found to give thermoluminescence peaks at temperatures higher than 560 K. It has also been found that reactor irradiation partially annihilates the trapping centres which are responsible for lower temperature glow peaks. 相似文献
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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
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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
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Studies on infrared and Raman-active phonons in the Aurivillius ferroelectric Bi2W2O9 were performed theoretically. The Raman and infrared phonons were calculated by applying a short-range force constant model using normal coordinates having space group Pna21. Sixteen stretching, two repulsive and seventeen bending force constants were used for the calculations of the zone center phonons. The calculated Raman and infrared wavenumbers are in very good agreement with the experimental ones in the literature. Potential energy distribution for this compound has also been investigated for the contribution of each force constant towards the Raman and the infrared wavenumbers. 相似文献
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