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161.
Dr. Chen Xue Shu Wang Prof. Dr. Wen-Long Liu Prof. Dr. Xiao-Ming Ren 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5280-5287
A direct band gap 2D corrugated layer lead chloride hybrid, [(CH3)4N]4Pb3Cl10 ( 1 ), shows analogous topology to the {Mg3F104−}∞ layer in Cs4Mg3F10, and with the (CH3)4N+ cations locating in the inorganic layer voids and between the interlayers. Two reversible structural phase transitions occur in 1 at 225/210 K and 328/325 K upon heating/cooling, respectively. On going from the low- to intermediate-temperature phase, the space group changes from P21/c to Cmca, and the crystallographic axis perpendicular to the layers is doubled with the order–disorder transformation of (CH3)4N + cations between the interlayers. The intermediate- and high-temperature phases are isomorphic with similar cell parameters and packing structure; their main difference concerns the disorder degree of the (CH3)4N + cations between the interlayers. The two-step structural phase transitions lead to dielectric anomalies around the corresponding Tc. Interestingly, 1 shows multiband emission, originating from the recombination of exciton and emission of defects. Moreover, 1 exhibits divergent thermochromic luminescent features around the Tc on the intermediate to low temperature transition. 相似文献
162.
Structural,morphological, and optical properties of tin(Ⅳ) oxide nanoparticles synthesized using Camellia sinensis extract: a green approach
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Tin oxide (SnO2) nanoparticles were cost-effectively synthesized using nontoxic chemicals and green tea (Camellia sinensis) extract via a green synthesis method.The structural properties of the obtained nanoparticles were studied using X-ray diffraction,which indicated that the crystallite size was less than 20 nm.The particle size and morphology of the nanoparticles were analyzed using scanning electron microscopy and transmission electron microscopy.The morphological analysis revealed agglomerated spherical nanoparticles with sizes varying from 5 to 30 nm.The optical properties of the nanoparticles' band gap were characterized using diffuse reflectance spectroscopy.The band gap was found to decrease with increasing annealing temperature.The O vacancy defects were analyzed using photoluminescence spectroscopy.The increase in the crystallite size,decreasing band gap,and the increasing intensities of the UV and visible emission peaks indicated that the green-synthesized SnO2 may play future important roles in catalysis and optoelectronic devices. 相似文献
163.
左半正则B-拟-Ehresmann半群 《山东科学》2017,30(2):110-102
良B-拟-Ehresmann半群是幂等元子带B满足一些条件的半群,其中B被称为投射带。纯整半群、型W半群、纯整超rpp半群和投射纯整幺半群都是良B-拟-Ehresmann半群。本文刻画了投射带是左半正则带的良B-拟-Ehresmann半群。 相似文献
164.
Auxiliary population information is often available in finite population inference problems, and the empirical likelihood (EL) approach has been demonstrated to be flexible and useful for such problems. The present paper concerns EL when interest centers on inference for the mean of the baseline distribution under two-sample density ratio models. Although dual EL is a convenient technical tool since it has the same maximum point and maximum likelihood as DRM-based EL, it can not combine such auxiliary information into the likelihood conveniently and may have loss of efficiency. By contrast, the classical EL approach of Qin and
Lawless\ucite{21} does not have this problem and incorporate seamlessly auxiliary information. Based on the EL using auxiliary information and the
dual EL methods, we construct both point and interval estimations and make a careful comparison. Though the point estimation efficiency gain obtained
by the former is not noticeable, we find that they may have different performances in interval estimation. In terms of coverage accuracy, the two intervals are comparable for not or moderate skewed populations, and the EL interval using auxiliary information can be much superior for severely skewed populations. 相似文献
165.
Dr. Kaitie C. Cartwright Ebbin Joseph Chelsea G. Comadoll Prof. Jon A. Tunge 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(54):12454-12471
Recently, dual-catalytic strategies towards the decarboxylative elimination of carboxylic acids have gained attention. Our lab previously reported a photoredox/cobaloxime dual catalytic method that allows the synthesis of enamides and enecarbamates directly from N-acyl amino acids and avoids the use of any stoichiometric reagents. Further development, detailed herein, has improved upon this transformation's utility and further experimentation has provided new insights into the reaction mechanism. These new developments and insights are anticipated to aid in the expansion of photoredox/cobalt dual-catalytic systems. 相似文献
166.
Jing Guo Mengli Wang Haitao Guo Ruimiao Chang Haixia Yu Guangbin Zhang Anjia Chen 《Biomedical chromatography : BMC》2019,33(11)
A simple, comprehensive and efficient capillary electrophoresis method using a dual cyclodextrin system was developed for the simultaneous determination of seven isoflavones (3′‐methoxypuerarin, puerarin, 3′‐hydroxypuerarin, ononin, daidzin, daidzein and genistin). Baseline separations of the seven isoflavones were achieved within 11 min with the running buffer consisting of 35 mm sodium tetraborate, 9.0 mm sulfobutylether‐β‐cyclodextrin and 30 mm α‐cyclodextrin at pH 9.34, and peaks were detected at 254 nm. Other separation parameters included the separation voltage for 15 kV and the working temperature for 25°C. Under the optimum conditions, good linearities were obtained with linear correlation coefficients of seven isoflavones of 0.9978–0.9992. The limits of detection and the limits of quantification were 0.7–2.9 and 2.5–9.5 μg/mL, respectively. Excellent precision and accuracy were obtained. The intraday and interday precision ranged from 0.7 to 2.0% and from 0.8 to 1.9%, respectively. The recoveries of seven analytes were from 97.7 to 103.1%. This method was successfully applied to determine the seven analytes in Radix Puerariae and its preparations. 相似文献
167.
N. Sharadhi S. Vimala K. Nurjahan B. N. Veerabhadraswamy C. V. Yelamaggad 《Liquid crystals》2020,47(2):211-218
ABSTRACT Blue phase liquid crystals are soft 3D photonic crystals in which the liquid crystal molecules self-assemble to form a cubic structure with lattice spacing of a few hundred nanometers resulting in selective reflection of colours in the visible spectrum. The corresponding wavelength or the ‘photonic band gap’ can be tuned using various external stimuli such as thermal, electric, magnetic and optical fields. Here, we report efficient tuning of photonic band gap by utilising the combination of electric and optical fields in a blue phase liquid crystalline system. The studies indicate that the chirality of the medium has a direct bearing on the direction of the wavelength shift and the extent of the photonic band gap tunability. More importantly, the synergistic effect of the two fields helps in reversible tuning of the band gap. 相似文献
168.
169.
《Mendeleev Communications》2020,30(5):666-668
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170.
Pham Duy Khanh Tran Hong Mo Trinh T. T. Tran 《Numerical Functional Analysis & Optimization》2019,40(8):924-943
Necessary and sufficient conditions for qualitative properties of infinite dimensional linear programing problems such as solvability, duality, and complementary slackness conditions are studied in this article. As illustrations for the results, we investigate the parametric version of Gale’s example. 相似文献