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971.
972.
Anilido-imine ligands o-C6H4(NHAr1)(CH=NAr2), in which Ar1 is 2,6-diisopropylbenzyl group and Ar2 contains fluorine (HL1) or methoxyl (HL2) group on ortho-position of phenyl substituent, were synthesized for constructing rare-earth metals based complexes of 1a–1c (HL1 based Sc, Lu, Y) and 2a–2c (HL2 based Sc, Lu, Y). Based on their NMR spectra and X-ray single-crystal structures, the side-arm group of -F and -OMe is identified to chelate to the corresponding central metal. The twisted angles between two planes formed by chelated heteroatoms (N, N, F for HL1 and N, N, O for HL2) are observed, in which the largest dihedral angle (53.3°) for HL1-Y and the smallest dihedral angle (44.32°) for HL2-Sc are detected. After being activated by AliBu3 and [Ph3C][B(C6F5)4], these catalysts showed great activity for isoprene polymerization. Bearing the same ligand HL1, smaller scandium based complex 1a and middle size of lutetium based 1b provided lower cis-1,4-selectivity (57.3% and 64.2%), larger yttrium complex 1c displayed high cis-1,4-selectivity (84%). Chelating by crowded HL2, small size of scandium complex 2a provided impressive trans-1,4-selectivity (93.0%), middle lutetium based 2b displayed non-selectivity and larger yttrium complex 2c showed clear cis-1,4-selectivity (83.3%). Moreover, 2a/AliBu3 system showed the quasi-living chain transfer capability. 相似文献
973.
Jianming Cui Wenxiu Kong Xiaojun Zhang Da Chen Qingtian Zeng 《Entropy (Basel, Switzerland)》2021,23(7)
Polar code has been adopted as the control channel coding scheme for the fifth generation (5G), and the performance of short polar codes is receiving intensive attention. The successive cancellation flipping (SC flipping) algorithm suffers a significant performance loss in short block lengths. To address this issue, we propose a double long short-term memory (DLSTM) neural network to locate the first error bit. To enhance the prediction accuracy of the DLSTM network, all frozen bits are clipped in the output layer. Then, Gaussian approximation is applied to measure the channel reliability and rank the flipping set to choose the least reliable position for multi-bit flipping. To be robust under different codewords, padding and masking strategies aid the network architecture to be compatible with multiple block lengths. Numerical results indicate that the error-correction performance of the proposed algorithm is competitive with that of the CA-SCL algorithm. It has better performance than the machine learning-based multi-bit flipping SC (ML-MSCF) decoder and the dynamic SC flipping (DSCF) decoder for short polar codes. 相似文献
974.
975.
Thermal modeling optimization and experimental validation for a single, concentrator solar cell system with a heat sink 下载免费PDF全文
A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance of the thermal conductive adhesive. Influence disciplines of those parameters on temperatures of the solar cell and heat sink are obtained. With optimized number, height and thickness of fins, and the thickness values of base of 8, 1.4 cm, 1.5 mm, and 2 mm, the lowest temperatures of the solar cell and heat sink are 41.7℃ and 36.3℃ respectively. A concentrator solar cell prototype with a heat sink fabricated based on the simulation optimized structure is built. Outdoor temperatures of the prototype are tested. Temperatures of the solar cell and heat sink are stabilized with time continuing at about 37℃-38℃ and 35℃-36℃ respectively, slightly lower than the simulation results because of effects of the wind and cloud. Thus the simulation model enables to predict the thermal performance of the system, and the simulation results can be a reference for designing heat sinks in the field of single concentrator solar cells. 相似文献
976.
Effects of effective attractive multi-body interaction on quantum phase and transport dynamics of a strongly correlated bosonic gas across the superfluid to Mott insulator transition 下载免费PDF全文
We theoretically investigate quantum phases and transport dynamics of ultracold atoms trapped in an optical lattice in the presence of effective multi-body interaction.When a harmonic external potential is added,several interesting phenomena are revealed,such as the broadening and the emergence of a central insulator plateau and the phase transition between superfluid and Mott insulator phase.We also study the transport of the system which runs across the superfluid–insulator transition after ramping up the lattice,and predict a slower relaxation which is attributed to the influence of the multi-body interaction on the mass transport. 相似文献
977.
Control of gain and thermal carrier loss profiles for mode optimization in 980-nm broad-area vertical-cavity surface-emitting lasers 下载免费PDF全文
Optical gain and thermal carrier loss distributions regarding current diffusion and various electric contact areas are investigated to improve the near-field modes from the ring-shape to a Gaussian-like configuration for extra-broad-area and oxide-confined vertical-cavity surface-emitting lasers. In this work an equivalent circuit network model is used. The resistance of the continuously-graded distributed Bragg reflectors (DBRs), the current diffusion and the temperature effect due to different electric-contact areas are calculated and analyzed at first, as these parameters affect one another and are the key factors in determining the gain and thermal carrier loss. Finally, the gain and thermal carrier loss distributions are calculated and discussed. 相似文献
978.
Shenmin Zhu Jingjing Guo Junping Dong Zhaowen Cui Tao Lu Chenglin Zhu Di Zhang Jun Ma 《Ultrasonics sonochemistry》2013,20(3):872-880
This study synthesized Fe3O4 nanoparticles of 30–40 nm by a sonochemical method, and these particles were uniformly dispersed on the reduced graphene oxide sheets (Fe3O4/RGO). The superparamagnetic property of Fe3O4/RGO was evidenced from a saturated magnetization of 30 emu/g tested by a sample-vibrating magnetometer. Based on the testing results, we proposed a mechanism of ultrasonic waves to explain the formation and dispersion of Fe3O4 nanoparticles on RGO. A biosensor was fabricated by modifying a glassy carbon electrode with the combination of Fe3O4/RGO and hemoglobin. The biosensor showed an excellent electrocatalytic reduction toward H2O2 at a wide, linear range from 4 × 10?6 to 1 × 10?3 M (R2 = 0.994) as examined by amperometry, and with a detection limit of 2 × 10?6 M. The high performance of H2O2 detection is attributed to the synergistic effect of the combination of Fe3O4 nanoparticles and RGO, promoting the electron transfer between the peroxide and electrode surface. 相似文献
979.
Ruohu Zhang Zhuyuan Wang Chunyuan Song Jing Yang Asma Sadaf Yiping Cui 《Journal of fluorescence》2013,23(1):71-77
A novel gap-plasmon-tunable Ag bilayer nanoparticle film for immunoassays is demonstrated. Different from a traditional Ag monolayer nanoparticle film, a desired number of polyelectrolyte (PEL) layers are deposited on the nanoparticles before the self-assembly of a second Ag nanoparticle layer. Interestingly, by controlling the number of the PEL interlayers, the gap plasmon between the two Ag nanoparticle layers can be tuned across the visible spectral range. The ability of the presented Ag bilayer nanoparticle films in fluorescence enhancement has been examined experimentally. A maximal enhancement of around 15.4 fold was achieved when 7 layers of polyelectrolyte were used. When this optimal Ag bilayer nanoparticle film was applied to fluorescence immunoassay, a performance with approximately 3.3-fold enhancement was obtained compared with that performed on a traditional glass substrate. The experimental results suggest that the presented gap-plasmon tunable Ag bilayer nanoparticle films have great potential in fluorescence-based immunoassays. The method of the bilayer-film construction presented here also provides new insights into the rational design of the plasmonic substrates. 相似文献
980.
Wenhe Du Feizhan Chen Zhongmin Yao Ruibo Ai Daosen Liu Quanling Cui 《Journal of Russian Laser Research》2013,34(4):351-355
In satellite–ground laser communications, atmospheric turbulence in the link degrades the performance of the system, so it is very important to estimate its influence on the performance of the system. The bit-error rate (BER) is an important parameter to indicate the communication performance of the system, which is directly used to judge the quality of the communication system. Using the results of our two previous papers, we analyze the joint influence of Kolmogorov turbulence from the ground up to 6 km and non-Kolmogorov turbulence above 6 km on the BER. These kinds of turbulence are associated respectively with the uplink and the downlink propagation channels for the geosynchronous orbit satellite communication system. 相似文献