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991.
Yong-Li Xu Yin-Lu Han Xin-Wu Su Xiao-Jun Sun Hai-Ying Liang Hai-Rui Guo Chong-Hai Cai 《中国物理C(英文版)》2020,44(12):124103-124103-10
We construct a new global optical model potential to describe the elastic scattering of 12C. The experimental data of elastic-scattering angular distributions and total reaction cross sections for targets from 24Mg to 209Bi are considered below 200 MeV within the framework of the optical model. The results calculated using the derived global optical potential are then compared with the existing experimental data. The reliability of the global optical potential is further tested by predicting the elastic scattering data out of the mass and energy ranges, within which the global potential parameters are determined, and reasonable results are also obtained. 相似文献
992.
The multicaloric effect refers to the thermal response of a solid material driven by simultaneous or sequential application of more than one type of external field.For practical applications,the multicaloric effect is a potentially interesting strategy to improve the efficiency of refrigeration devices.Here,the state of the art in multi-field driven multicaloric effect is reviewed.The phenomenology and fundamental thermodynamics of the multicaloric effect are well established.A number of theoretical and experimental research approaches are covered.At present,the theoretical understanding of the multicaloric effect is thorough.However,due to the limitation of the current experimental technology,the experimental approach is still in progress.All these researches indicated that the thermal response and effective reversibility of multiferroic materials can be improved through multicaloric cycles to overcome the inherent limitations of the physical mechanisms behind single-field-induced caloric effects.Finally,the viewpoint of further developments is presented. 相似文献
993.
994.
The two-dimensional (2D) C3N has emerged as a material with promising applications in high performance device owing to its intrinsic bandgap and tunable electronic properties. Although there are several reports about the bandgap tuning of C3N via stacking or forming nanoribbon, bandgap modulation of bilayer C3N nanoribbons (C3NNRs) with various edge structures is still far from well understood. Here, based on extensive first-principles calculations, we demonstrated the effective bandgap engineering of C3N by cutting it into hydrogen passivated C3NNRs and stacking them into bilayer heterostructures. It was found that armchair (AC) C3NNRs with three types of edge structures are all semiconductors, while only zigzag (ZZ) C3NNRs with edges composed of both C and N atoms (ZZCN/ CN) are semiconductors. The bandgaps of all semiconducting C3NNRs are larger than that of C3N nanosheet. More interestingly, AC-C3NNRs with CN/CN edges (AC-CN/CN) possess direct bandgap while ZZ-CN/CN have indirect bandgap. Compared with the monolayer C3NNR, the bandgaps of bilayer C3NNRs can be greatly modulated via different stacking orders and edge structures, varying from 0.43 eV for ZZ-CN/CN with AB′-stacking to 0.04 eV for AC-CN/CN with AA-stacking. Particularly, transition from direct to indirect bandgap was observed in the bilayer AC-CN/CN heterostructure with AA′-stacking, and the indirect-to-direct transition was found in the bilayer ZZ-CN/CN with ABstacking. This work provides insights into the effective bandgap engineering of C3N and offers a new opportunity for its applications in nano-electronics and optoelectronic devices. 相似文献
995.
Zhi-Xin Yang Liang Wang Yu-Mu Liu Dong-Yang Wang Cheng-Hua Bai Shou Zhang Hong-Fu Wang 《Frontiers of Physics》2020,15(5):52504
We propose to realize the ground state cooling of magnomechanical resonator in a parity–time (PT)-symmetric cavity magnomechanical system composed of a loss ferromagnetic sphere and a gain microwave cavity. In the scheme, the magnomechanical resonator can be cooled close to its ground state via the magnomechanical interaction, and it is found that the cooling effect in PT-symmetric system is much higher than that in non-PT-symmetric system. Resorting to the magnetic force noise spectrum, we investigate the final mean phonon number with experimentally feasible parameters and find surprisingly that the ground state cooling of magnomechanical resonator can be directly achieved at room temperature. Furthermore, we also illustrate that the ground state cooling can be flexibly controlled via the external magnetic field. 相似文献
996.
Xiang-Guo Meng Kai-Cai Li Ji-Suo Wang Zhen-Shan Yang Xiao-Yan Zhang Zhen-Tao Zhang Bao-Long Liang 《Frontiers of Physics》2020,15(5):52501
Using an operator ordering method for some commutative superposition operators, we introduce two new multi-variable special polynomials and their generating functions, and present some new operator identities and integral formulas involving the two special polynomials. Instead of calculating complicated partial differential, we use the special polynomials and their generating functions to concisely address the normalization, photocount distributions and Wigner distributions of several quantum states that can be realized physically, the results of which provide real convenience for further investigating the properties and applications of these states. 相似文献
997.
Haitao Han Liang Kan Ping Li Guoshuai Zhang Kaiyue Li Wuping Liao Yunling Liu Wei Chen Chunhua T.Hu 《中国科学:化学(英文版)》2021,(3):426-431
Three 4.8 nm isostructural{M72}(M=CoⅡ for CIAC-128,NiⅡ for CIAC-129,FeⅡ for CIAC-130) metal-organic polyhedra(MOPs) are constructed by eighteen M4-p-tert-butylthiacalix[4]arene (M4-TC4A) units bridged via sixteen four-connected 5,5′-(1H-1,2,4-triazole-3,5-diyl) diisophthalic acid (H4TADIPA) linkers.These MOPs are featured with a rarely reported concave coordination cage,which can be simplified as a squeezed double-decker hexagonal prism pressed from the top and bottom hexagonal faces.Furthermore,CIAC-128,CIAC-129 and CIAC-130 are the highest nuclearity discrete clusters of Co,Ni and Fe reported so far.CIAC-128 has higher separation selectivity of C3H8 than CH4 under ambient conditions,and also exhibits separation selectivity for C2H6/CH4,C2H2/CH4,and C2H4/CH4.In addition,CIAC-128 can provide the cavity for the confined synthesis of noble metal nanoclusters such as Pd nanoclusters and the resulting Pd@CIAC-128 hybrids show higher electrocatalytic activity than commercial Pt/C towards hydrogen evolution reaction (HER). 相似文献
998.
Wang Xiaofeng Yin Liang Yang Qingshan 《Archive of Applied Mechanics (Ingenieur Archiv)》2019,89(11):2361-2380
Archive of Applied Mechanics - Membranes are widely applied in the large-span buildings and spatial deployable structures. They are prone to wrinkle under compression due to their small bending... 相似文献
999.
考虑爆炸成型弹丸(explosively-formed projectile,EFP)变截面的特性,基于流体力学Bernoulli方程和绝热剪切理论,改进了EFP垂直侵彻装甲钢板靶后破片质量模型,结合已有的试验数据和数值仿真方法检验了改进后模型的准确性。在此基础上,分析了靶板厚度和EFP着靶速度对靶板和EFP产生的靶后破片质量的影响规律。结果表明:相比于改进前的模型,改进后的模型能够更准确地解释靶板和EFP产生的靶后破片质量随靶板厚度和EFP着靶速度的变化规律;当EFP着靶速度为1 650 m/s时,随着靶板厚度从30 mm增大到70 mm,EFP变截面的特性对靶板和EFP产生靶后破片质量的影响不断增强;当靶板厚度为40 mm时,随着EFP着靶速度从1 650 m/s升高到1 860 m/s,EFP变截面的特性对靶板和EFP产生靶后破片质量的影响不断减弱。 相似文献
1000.
Chao-Shen Zhang Bei-Bei Zhang Liang Zhong Xiang-Yu Chen Zhi-Xiang Wang 《Chemical science》2022,13(13):3728
A DFT study has been conducted to understand the asymmetric alkyl–alkyl bond formation through nickel-catalysed reductive coupling of racemic alkyl bromide with olefin in the presence of hydrosilane and K3PO4. The key findings of the study include: (i) under the reductive experimental conditions, the Ni(ii) precursor is easily activated/reduced to Ni(0) species which can serve as an active species to start a Ni(0)/Ni(ii) catalytic cycle. (ii) Alternatively, the reaction may proceed via a Ni(i)/Ni(ii)/Ni(iii) catalytic cycle starting with a Ni(i) species such as Ni(i)–Br. The generation of a Ni(i) active species via comproportionation of Ni(ii) and Ni(0) species is highly unlikely, because the necessary Ni(0) species is strongly stabilized by olefin. Alternatively, a cage effect enabled generation of a Ni(i) active catalyst from the Ni(ii) species involved in the Ni(0)/Ni(ii) cycle was proposed to be a viable mechanism. (iii) In both catalytic cycles, K3PO4 greatly facilitates the hydrosilane hydride transfer for reducing olefin to an alkyl coupling partner. The reduction proceeds by converting a Ni–Br bond to a Ni–H bond via hydrosilane hydride transfer to a Ni–alkyl bond via olefin insertion. On the basis of two catalytic cycles, the origins for enantioconvergence and enantioselectivity control were discussed.The enantioconvergent alkyl–alkyl coupling involves two competitive catalytic cycles with nickel(0) and nickel(i) active catalysts, respectively. K3PO4 plays a crucial role to enable the hydride transfer from hydrosilane to nickel–bromine species. 相似文献