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In the present review, data on methods of synthesis, reactivity, biological activity and structure of α-carbofunctional silanols having X—C—SiOH (X = Hal, O, S, N) geminal moiety, have been classified and analyzed.  相似文献   

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Monoclonal antibodies have become a viable strategy for the delivery of therapeutic, particle emitting radionuclides specifically to tumor cells to either augment anti-tumor action of the native antibodies or to solely take advantage of their action as targeting vectors. Proper and rational selection of radionuclide and antibody combinations is critical to making radioimmunotherapy (RIT) a standard therapeutic modality due to the fundamental and significant differences in the emission of either alpha- and beta-particles. The alpha-particle has a short path length (50-80 microm) that is characterized by high linear energy transfer (100 keV microm(-1)). Actively targeted alpha-therapy potentially offers a more specific tumor cell killing action with less collateral damage to the surrounding normal tissues than beta-emitters. These properties make targeted alpha-therapy an appropriate therapy to eliminate minimal residual or micrometastatic disease. RIT using alpha-emitters such as (213)Bi, (211)At, (225)Ac, and others has demonstrated significant activity in both in vitro and in vivo model systems. Limited numbers of clinical trials have progressed to demonstrate safety, feasibility, and therapeutic activity of targeted alpha-therapy, despite having to traverse complex obstacles. Further advances may require more potent isotopes, additional sources and more efficient means of isotope production. Refinements in chelation and/or radiolabeling chemistry combined with rational improvements of isotope delivery, targeting vectors, molecular targets, and identification of appropriate clinical applications remain as active areas of research. Ultimately, randomized trials comparing targeted alpha-therapy combined with integration into existing standards of care treatment regimens will determine the clinical utility of this modality.  相似文献   

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《大学化学》2021,36(6)
过氧化氢,结构微妙,用途广泛,在漂白、医药、化工、环保、食品工业、火箭燃料等多行业发挥重要作用。本文在简述过氧化氢的结构、性质和合成的基础上,重点讨论其生物学功能、检测方法、应用、安全性等,增加人们对过氧化氢的进一步了解。  相似文献   

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Summary A -SCF/Molecular Mechanics method (PIMM) for the calculation of heats of formation, molecular geometries and charge density distributions of organic molecules is described. The method combines a -SCF molecular orbital calculation and the -charge evaluation procedure PEOE of Marsilli and Gasteiger with molecular mechanics. The formulas and parameters use are given. A series of results for small molecules is presented and compared with experimental data.  相似文献   

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Ab initio MP2/aug’-cc-pVTZ calculations have been carried out to investigate H2CO : PXH2 pnicogen-bonded complexes and HCO2H : PXH2 complexes that are stabilized by pnicogen bonds and hydrogen bonds, with X=NC, F, Cl, CN, OH, CCH, CH3, and H. The binding energies of these complexes exhibit a second-order dependence on the O−P distance. DFT-SAPT binding energies correlate linearly with MP2 binding energies. The HCO2H : PXH2 complexes are stabilized by both a pnicogen bond and a hydrogen bond, resulting in greater binding energies for the HCO2H : PXH2 complexes compared to H2CO : PXH2. Neither the O−P distance across the pnicogen bond nor the O−P distance across the hydrogen bond correlates with the binding energies of these complexes. The nonlinearity of the hydrogen bonds suggests that they are relatively weak bonds, except for complexes in which the substituent X is either CH3 or H. The pnicogen bond is the more important stabilizing interaction in the HCO2H : PXH2 complexes except when the substituent X is a more electropositive group. EOM-CCSD spin-spin coupling constants 1pJ(O−P) across pnicogen bonds in H2CO:PXH2 and HCO2H : PXH2 complexes increase as the O−P distance decreases, and exhibit a second order dependence on that distance. There is no correlation between 2hJ(O−P) and the O−P distance across the hydrogen bond in the HCO2H : PXH2 complexes. 2hJ(O−P) coupling constants for complexes with X=CH3 and H have much greater absolute values than anticipated from their O−P distances.  相似文献   

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.  相似文献   

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Aluminum hydride(AlH3) is a binary metal hydride that contains more than 10.1 wt% of hydrogen and possesses a high volumetric hydrogen density of 148 kg H2 m-3.Pristine AlH3 can readily release hydrogen at a moderate temperature below 200℃.Such high hydrogen density and low desorption temperature make AlH3 one of most promising hydrogen storage media for mobile application.This review covers the research activity on the structures,synthesis,decomposition thermodynamics and kinetics,regeneration and application validation of AlH3 over the past decades.Finally,the future research directions of AlH3 as a hydrogen storage material will be revealed.  相似文献   

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Distance-of-flight mass spectrometry (DOFMS) separates ions of different mass-to-charge (m/z) by the distance they travel in a given time after acceleration. Like time-of-flight mass spectrometry (TOFMS), separation and mass assignment are based on ion velocity. However, DOFMS is not a variant of TOFMS; different methods of ion focusing and detection are used. In DOFMS, ions are driven orthogonally, at the detection time, onto an array of detectors parallel to the flight path. Through the independent detection of each m/z, DOFMS can provide both wider dynamic range and increased throughput for m/z of interest compared with conventional TOFMS. The iso-mass focusing and detection of ions is achieved by constant-momentum acceleration (CMA) and a linear-field ion mirror. Improved energy focus (including turn-around) is achieved in DOFMS, but the initial spatial dispersion of ions remains unchanged upon detection. Therefore, the point-source nature of surface ionization techniques could put them at an advantage for DOFMS. To date, three types of position-sensitive detectors have been used for DOFMS: a microchannel plate with a phosphorescent screen, a focal plane camera, and an IonCCD array; advances in detector technology will likely improve DOFMS figures-of-merit. In addition, the combination of CMA with TOF detection has provided improved resolution and duty factor over a narrow m/z range (compared with conventional, single-pass TOFMS). The unique characteristics of DOFMS can enable the intact collection of large biomolecules, clusters, and organisms. DOFMS might also play a key role in achieving the long-sought goal of simultaneous MS/MS.
Graphical Abstract ?
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A second polymorph of technetium trichloride, β-TcCl(3), has been identified from the reaction between Tc metal and Cl(2) gas. The structure of β-TcCl(3) consists of infinite layers of edge-sharing octahedra, similar to its MoCl(3) and RuCl(3) analogues. The Tc-Tc distance [2.861(3) ?] between adjacent octahedra is indicative of metal-metal bonding. Earlier theoretical work predicted that β-TcCl(3) is less stable than α-TcCl(3). In agreement with the prediction, β-TcCl(3) slowly transforms into α-TcCl(3) (Tc(3)Cl(9)) over 16 days at 280 °C.  相似文献   

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We present a theoretical investigation of the hydrogenation of pyrene and of the subsequent molecular hydrogen evolution. Using density functional theory (DFT) at the GGA-PBE level, the chemical binding of atomic hydrogen to pyrene is found to be exothermic by up to 1.6 eV with a strong site dependence. The edge C atoms are found most reactive. The barrier for the formation of the hydrogen-pyrene bond is small, down to 0.06 eV. A second hydrogen binds barrierless at many sites. The most stable structure of dihydrogenpyrene is more stable by 0.64 eV than pyrene plus a molecular hydrogen molecule and a large barrier of 3.7 eV for the molecular hydrogen evolution is found. Using a simple tight-binding model we demonstrate that the projected density of π-states can be used to predict the most stable binding sites for hydrogen atoms and the model is used to investigate the most favorable binding sites on more hydrogenated pyrene molecules and on coronene. Some of the DFT calculations were complemented with hybrid-DFT (PBE0) showing a general agreement between the DFT and hybrid-DFT results.  相似文献   

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本文较系统地研究了LaOBr∶Er,LaOBr∶Tm和LaOBr∶Er,Tm的发光特性。用不同波长的光源激发样品,确定Er~(3 )和Tm~(3 )的荧光衰减及强度与浓度的依赖关系,并得到临界传递距离R_0=59.4。  相似文献   

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Peptide-cyclodextrin and protein-cyclodextrin host-guest complexes are becoming more and more important for industrial applications, in particular in the fields of pharmaceutical and food chemistry. They have already deserved many experimental investigations although the effect of complex formation in terms of peptide (or protein) structure is not well-known yet. Theoretical calculations represent a unique tool to analyze such effects, and with this aim we have carried out in the present investigation molecular dynamics simulations and combined quantum mechanics-molecular mechanics calculations. We have studied complexes formed between the model Ace-Phe-Nme peptide and the β-cyclodextrin (β-CD) macromolecule, and our analysis focuses on the following points: (1) how is the peptide structure modified in going from bulk water to CD environment (backbone torsion angles), (2) which are the main peptide-CD interactions, in particular in terms of hydrogen bonds, (3) which relative peptide-CD orientation is preferred and which are the structural and energetic differences between them, and (4) how the electronic properties of the peptide changes under complex formation. Overall, our calculations show that in the most stable configuration, the backbone chain lies in the narrow rim of the CD. Strong hydrogen bonds form between the H atoms of the peptidic NH groups and oxygen atoms of the secondary OH groups in the CD. These and other (weaker) hydrogen bonds formed by the carbonyl groups reduce considerably the flexibility of the peptide structure, compared to bulk water, and produce a marked increase of the local dipole moment by favoring configurations in which the two C═O bonds point toward the same direction. This effect might have important consequences in terms of the peptide secondary structure, although this hypothesis needs to be tested using larger peptide models.  相似文献   

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