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941.
In this paper, we develop a stochastic calculus related to a fractional Brownian sheet as in the case of the standard Brownian sheet. Let be a fractional Brownian sheet with Hurst parameters H=(H1,H2), and (2[0,1],B(2[0,1]),μ) a measure space. By using the techniques of stochastic calculus of variations, we introduce stochastic line integrals along all sufficiently smooth curves γ in 2[0,1], and four types of stochastic surface integrals: , i=1,2, , , , . As an application of these stochastic integrals, we prove an Itô formula for fractional Brownian sheet with Hurst parameters H1,H2∈(1/4,1). Our proof is based on the repeated applications of Itô formula for one-parameter Gaussian process. 相似文献
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946.
Nonspherical cages in inclusion compounds can result in non‐uniform motion of guest species in these cages and anisotropic lineshapes in NMR spectra of the guest. Herein, we develop a methodology to calculate lineshape anisotropy of guest species in cages based on molecular dynamics simulations of the inclusion compound. The methodology is valid for guest atoms with spin 1/2 nuclei and does not depend on the temperature and type of inclusion compound or guest species studied. As an example, the nonspherical shape of the structure I (sI) clathrate hydrate large cages leads to preferential alignment of linear CO2 molecules in directions parallel to the two hexagonal faces of the cages. The angular distribution of the CO2 guests in terms of a polar angle θ and azimuth angle ? and small amplitude vibrational motions in the large cage are characterized by molecular dynamics simulations at different temperatures in the stability range of the CO2 sI clathrate. The experimental 13C NMR lineshapes of CO2 guests in the large cages show a reversal of the skew between the low temperature (77 K) and the high temperature (238 K) limits of the stability of the clathrate. We determine the angular distributions of the guests in the cages by classical MD simulations of the sI clathrate and calculate the 13C NMR lineshapes over a range of temperatures. Good agreement between experimental lineshapes and calculated lineshapes is obtained. No assumptions regarding the nature of the guest motions in the cages are required. 相似文献
947.
Jingnan Wu Zhaoheng Ling Leandro R. Franco Sang Young Jeong Zewdneh Genene Josué Mena Si Chen Cailing Chen Prof. C. Moyses Araujo Prof. Cleber F. N. Marchiori Joost Kimpel Xiaoming Chang Furkan H. Isikgor Qiaonan Chen Hendrik Faber Prof. Yu Han Frédéric Laquai Prof. Maojie Zhang Prof. Han Young Woo Prof. Donghong Yu Prof. Thomas D. Anthopoulos Prof. Ergang Wang 《Angewandte Chemie (International ed. in English)》2023,62(45):e202302888
The determination of molecular conformations of oligomeric acceptors (OAs) and their impact on molecular packing are crucial for understanding the photovoltaic performance of their resulting polymer solar cells (PSCs) but have not been well studied yet. Herein, we synthesized two dimeric acceptor materials, DIBP3F-Se and DIBP3F-S, which bridged two segments of Y6-derivatives by selenophene and thiophene, respectively. Theoretical simulation and experimental 1D and 2D NMR spectroscopic studies prove that both dimers exhibit O-shaped conformations other than S- or U-shaped counter-ones. Notably, this O-shaped conformation is likely governed by a distinctive “conformational lock” mechanism, arising from the intensified intramolecular π–π interactions among their two terminal groups within the dimers. PSCs based on DIBP3F-Se deliver a maximum efficiency of 18.09 %, outperforming DIBP3F-S-based cells (16.11 %) and ranking among the highest efficiencies for OA-based PSCs. This work demonstrates a facile method to obtain OA conformations and highlights the potential of dimeric acceptors for high-performance PSCs. 相似文献
948.
Dr. Jianfeng Li Dr. Zhicai Chen Junwei Wang Sang Young Jeong Dr. Kun Yang Dr. Kui Feng Jie Yang Dr. Bin Liu Prof. Dr. Han Young Woo Prof. Dr. Xugang Guo 《Angewandte Chemie (International ed. in English)》2023,62(38):e202307647
Developing high-performance but low-cost n-type polymers remains a significant challenge in the commercialization of organic field-effect transistors (OFETs). To achieve this objective, it is essential to design the key electron-deficient units with simple structures and facile preparation processes, which can facilitate the production of low-cost n-type polymers. Herein, by sequentially introducing fluorine and cyano functionalities onto trans-1,3-butadiene, we developed a series of structurally simple but highly electron-deficient building blocks, namely 1,4-dicyano-butadiene ( CNDE ), 3-fluoro-1,4-dicyano-butadiene ( CNFDE ), and 2,3-difluoro-1,4-dicyano-butadiene ( CNDFDE ), featuring a highly coplanar backbone and deep-positioned lowest unoccupied molecular orbital (LUMO) energy levels (−3.03–4.33 eV), which render them highly attractive for developing n-type semiconducting polymers. Notably, all these electron-deficient units can be easily accessed by a two-step high-yield synthetic procedure from low-cost raw materials, thus rendering them highly promising candidates for commercial applications. Upon polymerization with diketopyrrolopyrrole ( DPP ), three copolymers were developed that demonstrated unipolar n-type transport characteristics in OFETs with the highest electron mobility of >1 cm2 V−1 s−1. Hence, CNDE , CNFDE , and CNDFDE represent a class of novel, simple, and efficient electron-deficient units for constructing low-cost n-type polymers, thereby providing valuable insight for OFET applications. 相似文献
949.
In Gyu Kim Won Ho Jung Gayeon You Hyukjin Lee Yoo Jin Shin Sun Woo Lim Byung Ha Chung Hyejung Mok 《Macromolecular bioscience》2023,23(4):2200423
In this study, a novel polyhistidine-incorporated lipid nanoparticle (pHis/LNP) is developed for the delivery of therapeutic globotriaosylceramide (Gb3) synthase siRNAs using a microfluidic device with pHis as a biocompatible method of endosome escape. To inhibit the expression of Gb3 synthase, six siRNAs against Gb3 synthase are designed and an optimal siRNA sequence is selected. Selected Gb3 synthase siRNA is incorporated into pHis/LNP to prepare a spherical siRNA pHis/LNP with a size of 62.5 ± 1.9 nm and surface charge of −13.3 ± 4.2 mV. The pHis/LNP successfully protects siRNAs from degradation in 50% serum condition for 72 h. Prepared pHis/LNP exhibits superior stability for 20 days and excellent biocompatibility for A549 cells. After treatment with fluorescence-labeled LNPs, dotted fluorescent signals are co-localized with Lysotracker in cells with LNPs, whereas strong and diffused fluorescence intensity is observed in cells with pHis/LNPs probably due to successful endosomal escape. The extent of Gb3 synthase gene silencing by siRNA pHis/LNP is greatly improved (6.0-fold) compared to that by siRNA/LNP. Taken together, considering that the fabricated siRNA pHis/LNP exhibits excellent biocompatibility and superior gene silencing activity over conventional LNP, these particles can be utilized for the delivery of a wide range of therapeutic siRNAs. 相似文献
950.
Dr. Wengao Zhao Dr. Kuan Wang Prof. Xinming Fan Fucheng Ren Xieyu Xu Dr. Yangyang Liu Dr. Shizhao Xiong Dr. Xiangsi Liu Zhengfeng Zhang Mayan Si Ruizhuo Zhang Dr. Wessel van den Bergh Prof. Pengfei Yan Dr. Corsin Battaglia Dr. Torsten Brezesinski Prof. Yong Yang 《Angewandte Chemie (International ed. in English)》2023,62(32):e202305281
Single-crystal LiNixCoyMnzO2 (SC-NCM, x+y+z=1) cathodes are renowned for their high structural stability and reduced accumulation of adverse side products during long-term cycling. While advances have been made using SC-NCM cathode materials, careful studies of cathode degradation mechanisms are scarce. Herein, we employed quasi single-crystalline LiNi0.65Co0.15Mn0.20O2 (SC-NCM65) to test the relationship between cycling performance and material degradation for different charge cutoff potentials. The Li/SC-NCM65 cells showed >77 % capacity retention below 4.6 V vs. Li+/Li after 400 cycles and revealed a significant decay to 56 % for 4.7 V cutoff. We demonstrate that the SC-NCM65 degradation is due to accumulation of rock-salt (NiO) species at the particle surface rather than intragranular cracking or side reactions with the electrolyte. The NiO-type layer formation is also responsible for the strongly increased impedance and transition-metal dissolution. Notably, the capacity loss is found to have a linear relationship with the thickness of the rock-salt surface layer. Density functional theory and COMSOL Multiphysics modeling analysis further indicate that the charge-transfer kinetics is decisive, as the lower lithium diffusivity of the NiO phase hinders charge transport from the surface to the bulk. 相似文献