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101.
102.
采用火焰原子吸收光谱法测定镍基高温合金中的镉,样品以硝酸-氢氟酸-水混合溶液(1+1+1)前处理,选择Cd 228.8 nm为分析线进行测定,并通过标准加入法校正基体效应。考察了消解酸的选择,仪器工作参数的调整,基体和共存离子对镉测定的影响。结果表明,镍基高温合金中镉的检出限为0.088μg/g。加标回收率为94.1%~109%,结果的相对标准偏差(RSD,n=8)在0.54%~1.6%。方法操作简便、分析速度快、准确度好,适用于镉含量在0.0001%~0.001%的镍基高温合金中的测定。 相似文献
103.
Christophe Narth Louis Lagardère Étienne Polack Nohad Gresh Qiantao Wang David R. Bell Joshua A. Rackers Jay W. Ponder Pengyu Y. Ren Jean‐Philip Piquemal 《Journal of computational chemistry》2016,37(5):494-506
We propose a general coupling of the Smooth Particle Mesh Ewald SPME approach for distributed multipoles to a short‐range charge penetration correction modifying the charge‐charge, charge‐dipole and charge‐quadrupole energies. Such an approach significantly improves electrostatics when compared to ab initio values and has been calibrated on Symmetry‐Adapted Perturbation Theory reference data. Various neutral molecular dimers have been tested and results on the complexes of mono‐ and divalent cations with a water ligand are also provided. Transferability of the correction is adressed in the context of the implementation of the AMOEBA and SIBFA polarizable force fields in the TINKER‐HP software. As the choices of the multipolar distribution are discussed, conclusions are drawn for the future penetration‐corrected polarizable force fields highlighting the mandatory need of non‐spurious procedures for the obtention of well balanced and physically meaningful distributed moments. Finally, scalability and parallelism of the short‐range corrected SPME approach are addressed, demonstrating that the damping function is computationally affordable and accurate for molecular dynamics simulations of complex bio‐ or bioinorganic systems in periodic boundary conditions. © 2016 Wiley Periodicals, Inc. 相似文献
104.
Li L Kresh JA Karabacak NM Cobb JS Agar JN Hong P 《Journal of the American Society for Mass Spectrometry》2008,19(12):1867-1874
This article presents a memory efficient algorithm for accurately calculating the isotopic fine structures of molecules. Treating individual isotopic species of a molecule as different mass states, we introduce the concept of transitions between mass states and represent all mass states of the molecule in a hierarchical structure. We show that there exists a simple relationship between two different mass states at two different levels of the hierarchical structure. This allows us to efficiently and accurately compute both the mass and the abundance of every mass state of a small to medium-sized molecule, whose gross structures include small number of fine structures. A truncated calculation of this algorithm can be applied to calculate a majority of isotopic species (99.99% of cumulative abundance) of a large molecule. 相似文献
105.
XIAO Long WU Huirong ZHANG Yong SUN Hao ZHANG Wenchao LYU Fenglei DENG Zhao PENG Yang 《高等学校化学研究》2023,39(2):219-223
Oxygen evolution reaction(OER) plays a key role in the electrochemical conversion and storage processes, but the sluggish kinetics of OER strongly impedes its large-scale applications. We herein reported the in situ growth of Fe-benzenedicarboxylate(Fe-BDC) on Co(OH)2 nanoplates[Fe-BDC/ Co(OH)2] that showed remarkably enhanced OER activity than the pristine Co(OH)2. The incorporation of Fe species could enhance the intrinsic OER activity of Co and BDC could increase the electro-chemically active surface area(ECSA), thus resulting in dramatically enhanced OER activity. In situ Raman spectroscopy characterization disclosed that Fe-CoOOH reconstructed from Fe-BDC/Co(OH)2 was the real active site for OER. This work highlights the significance of rational tailoring of the nanostructure and electronic structure of Co(OH)2 and provides more opportunities for its widespread applications. 相似文献
106.
Changhao Wang Peter H. Nguyen Kevin Pham Danielle Huynh Thanh‐Binh Nancy Le Hongli Wang Pengyu Ren Ray Luo 《Journal of computational chemistry》2016,37(27):2436-2446
Molecular Mechanics Poisson–Boltzmann Surface Area (MMPBSA) methods have become widely adopted in estimating protein–ligand binding affinities due to their efficiency and high correlation with experiment. Here different computational alternatives were investigated to assess their impact to the agreement of MMPBSA calculations with experiment. Seven receptor families with both high‐quality crystal structures and binding affinities were selected. First the performance of nonpolar solvation models was studied and it was found that the modern approach that separately models hydrophobic and dispersion interactions dramatically reduces RMSD's of computed relative binding affinities. The numerical setup of the Poisson–Boltzmann methods was analyzed next. The data shows that the impact of grid spacing to the quality of MMPBSA calculations is small: the numerical error at the grid spacing of 0.5 Å is already small enough to be negligible. The impact of different atomic radius sets and different molecular surface definitions was further analyzed and weak influences were found on the agreement with experiment. The influence of solute dielectric constant was also analyzed: a higher dielectric constant generally improves the overall agreement with experiment, especially for highly charged binding pockets. The data also showed that the converged simulations caused slight reduction in the agreement with experiment. Finally the direction of estimating absolute binding free energies was briefly explored. Upon correction of the binding‐induced rearrangement free energy and the binding entropy lost, the errors in absolute binding affinities were also reduced dramatically when the modern nonpolar solvent model was used, although further developments were apparently necessary to further improve the MMPBSA methods. © 2016 Wiley Periodicals, Inc. 相似文献
107.
Dr. Yu Cao Dr. David T. Rodgers Dr. Juanjuan Du Insha Ahmad Eric N. Hampton Dr. Jennifer S. Y. Ma Dr. Magdalena Mazagova Dr. Sei‐hyun Choi Dr. Hwa Young Yun Dr. Han Xiao Dr. Pengyu Yang Xiaozhou Luo Dr. Reyna K. V. Lim Holly M. Pugh Dr. Feng Wang Dr. Stephanie A. Kazane Dr. Timothy M. Wright Dr. Chan Hyuk Kim Prof. Peter G. Schultz Dr. Travis S. Young 《Angewandte Chemie (International ed. in English)》2016,55(26):7520-7524
Chimeric antigen receptor T (CAR‐T) cells have demonstrated promising results against hematological malignancies, but have encountered significant challenges in translation to solid tumors. To overcome these hurdles, we have developed a switchable CAR‐T cell platform in which the activity of the engineered cell is controlled by dosage of an antibody‐based switch. Herein, we apply this approach to Her2‐expressing breast cancers by engineering switch molecules through site‐specific incorporation of FITC or grafting of a peptide neo‐epitope (PNE) into the anti‐Her2 antibody trastuzumab (clone 4D5). We demonstrate that both switch formats can be readily optimized to redirect CAR‐T cells (specific for the corresponding FITC or PNE) to Her2‐expressing tumor cells, and afford dose‐titratable activation of CAR‐T cells ex vivo and complete clearance of the tumor in rodent xenograft models. This strategy may facilitate the application of immunotherapy to solid tumors by affording comparable efficacy with improved safety owing to switch‐based control of the CAR‐T response. 相似文献
108.
Modeling the change in the electrostatics of organic molecules upon moving from vacuum into solvent, due to polarization, has long been an interesting problem. In vacuum, experimental values for the dipole moments and polarizabilities of small, rigid molecules are known to high accuracy; however, it has generally been difficult to determine these quantities for a polar molecule in water. A theoretical approach introduced by Onsager [J. Am. Chem. Soc. 58, 1486 (1936)] used vacuum properties of small molecules, including polarizability, dipole moment, and size, to predict experimentally known permittivities of neat liquids via the Poisson equation. Since this important advance in understanding the condensed phase, a large number of computational methods have been developed to study solutes embedded in a continuum via numerical solutions to the Poisson-Boltzmann equation. Only recently have the classical force fields used for studying biomolecules begun to include explicit polarization in their functional forms. Here the authors describe the theory underlying a newly developed polarizable multipole Poisson-Boltzmann (PMPB) continuum electrostatics model, which builds on the atomic multipole optimized energetics for biomolecular applications (AMOEBA) force field. As an application of the PMPB methodology, results are presented for several small folded proteins studied by molecular dynamics in explicit water as well as embedded in the PMPB continuum. The dipole moment of each protein increased on average by a factor of 1.27 in explicit AMOEBA water and 1.26 in continuum solvent. The essentially identical electrostatic response in both models suggests that PMPB electrostatics offers an efficient alternative to sampling explicit solvent molecules for a variety of interesting applications, including binding energies, conformational analysis, and pK(a) prediction. Introduction of 150 mM salt lowered the electrostatic solvation energy between 2 and 13 kcalmole, depending on the formal charge of the protein, but had only a small influence on dipole moments. 相似文献
109.
可充电镁电池具有理论体积比容量大、 地壳丰度高、 成本低、 环境友好及更为安全等优点, 是未来高能量存储系统发展的重要方向之一. 在大多数传统电解液中, 镁金属负极表面形成的钝化膜会阻碍镁的可逆沉积溶解过程, 从而限制了可充电镁电池的商业化应用. 由于存在成本高、 合成步骤复杂、 离子电导率低及难以同时与正负极兼容等问题, 聚焦于解决镁负级钝化问题的电解液研究陷入瓶颈. 因此, 通过对镁电池负极进行修饰改性, 使其在传统电解液中实现可逆过程是一种具有发展前景的策略. 本文从合金负极及人工界面形成两方面总结了近年来用于可充电镁电池负极改性的策略, 并在分析对比的基础上提出了进一步发展的结论和展望. 相似文献
110.
通过一步液滴法在不同的反应溶剂体系下制备了一系列无定形硅铝酸盐载体, 并进一步制备出Pd基负载型多孔催化材料, 探究了反应溶剂极性和反应物Si/Al比对载体材料和催化剂的影响, 实现了通过一步液滴法调控硅铝酸盐酸性和孔道属性. 结果表明, 在极性较小的反应溶剂体系中制得了富含介孔的无定形硅铝酸盐载体材料, 并且通过改变Si/Al比可实现载体材料的酸性、 比表面积及孔道尺寸的调控, 比表面积和总酸量分别达到349.6 m2/g和1.389 mmol/g. 由于该载体材料高的比表面积及丰富的介孔孔道, 所制得的Pd基负载型多孔催化材料的Pd金属分散性达到了63.17%, 在硝基苯加氢反应中实现了99.75%的转化率和94.62%的选择性, 在苯甲醇氧化反应中表现出40.61%的转化率及38.09%的选择性, 远远优于利用商用载体合成的 Pd/Al2O3催化材料. 这种简单有效的合成方法使得按照目标催化反应的类型来设计高效催化剂成为可能. 相似文献