Application of Schrödinger equation to study the tunnelling dynamics of proton transfer in the hydrogen bond of 2,5-dinitrobenzoic acid: proton T1 T1rho, and deuteron T1 relaxation methods

Temperature measurements of proton T1 (24.7 MHz), deuteron (deuterated hydroxyl group) T1 (55.2 MHz), and proton T1(rho) (B1 = 9 G) spin-lattice relaxation times of 2,5-dinitrobenzoic acid have been performed. An analysis of present experimental data together with previously published proton T1 (55.2 MHz) data has revealed the following molecular motions: proton/deuteron transfer in the hydrogen bond and two-site hopping of the whole dimer. It is shown that the proton-transfer dynamics are characterized by two correlation times tau(ov) and tau(tu), describing two fundamentally different motional processes, namely, thermally activated jumps over the barrier and tunneling through the barrier. The temperature dependence of 1/tau(tu) is the solution of Schr?dinger's equation, which also yields the temperature T(tun), where begins the tunnel pathway for proton transfer. A new equation for the spectral density function of complex motion consisting of the three motions is derived. The third motion (two-site hopping of the whole dimer characterized by tau(lib) correlation time) is responsible for a proton T1(rho) minimum in high temperatures, just below the melting point. Such a minimum is not reached by T1 temperature dependencies. The minimum of T1(rho) assigned to the classical hopping of a hydrogen-bonded proton occurs in the same low-temperature regime in which the flattening of the temperature dependencies of T1 points to the dominance of incoherent tunneling. This experimental fact denies the known theories predicting the intermediate temperature regime where a smooth transition between classical and quantum tunneling dynamics is expected. The fit of the derived theoretical equations to the experimental data T1(rho) and T1 is satisfactory. The correlation times obtained for deuterons indicate deuteron-transfer dynamics much slower than proton-transfer dynamics. It is concluded that the classical proton transfer takes place over the whole temperature regime, while the incoherent tunneling occurs below 46.5 (hydrogen) or 87.2 K (deuterium) only.     

T1-T2双模式磁共振造影剂的设计及应用

核磁共振成像作为一种无侵入的早期诊断方式早已在临床上得到了非常广泛的应用,其成像方式分为弛豫加权和扩散加权,其中弛豫加权又分为T₁加权成像和T₂加权成像。为了增强MR图像对比度,可通过引入造影剂,根据其增强类型可以分为阳性的T₁造影剂和阴性的T₂造影剂。虽然两种造影剂各有其优点,但是也存在着一些不足,因此一种全新的T₁-T₂双模态造影剂应运而生。T₁-T₂双模态造影剂的优势就在于可以利用同一台仪器,实现MRI成像在时间和空间上的精确匹配。本文系统地总结了T₁-T₂双模态造影剂的设计思路和其化学合成方法,并对其生物医学应用作了介绍。     

PρT measurements and derived properties of liquid 1-alkanols

The density of compressed liquid (C2 to C11) 1-alkanols was measured with a vibration tube densimeter over the temperature range from (278.15 to 358.15) K and pressures up to 60 MPa, with an uncertainty of ±0.0012 g · cm⁻³. Density values were correlated with pressure and temperature by the TRIDEN 10-parameter equation. Isothermal compressibility, isobaric thermal expansivity and internal pressure were calculated from the experimental results. The influence of the carbon-chain lengths over the thermophysical properties obtained was studied.     

C60的激发态光谱S1→Sn,T1→Tn与反饱和吸收

用ＩＮＤＯ／ＣＴ方法研究了Ｃ６０分子的电子结构及基态和激发态光谱（Ｓ０→Ｓｎ，Ｓ１→Ｓｎ，Ｔ１→Ｔｎ），激发态分子动态学和反饱和吸收的微观机制，用动态模型解速率方程，实现反饱和吸收的必要条件是激发态对激光的吸收截面，在波长５３２ｎｍ的激光作用下，Ｃ６０满足该条件，故Ｃ６０呈现反饱合吸收特征，理论分析与实验结果一致。     

环丁酮光化学反应中S1/T1/S0交叉点的重要作用

势能面间的交叉在光化学反应中起着重要的作用 ,是由激发态反应物到基态产物发生无辐射跃迁的机制 .在本文中 ,我们用 CASSCF和态平均 CASSCF方法分别对环丁酮光化学反应的势能剖面及 S1,T1和 S0三个势能面间交叉进行了研究 .结果发现 ,基态和三态产物的形成是通过 S1,T1和 S0三个势能面交叉于同一区域 (称为 S1/T1/S0交叉点 )这一有效途径完成的 .　　60年代末 ,实验 [1－ 9]发现环丁酮和其它烷基酮 ,如丙酮、环戊酮的光化学反应机理很不一致 .主要体现在 ,i)环丁酮 (n,π态 )的α解离发生在 S1态势能面上 ,而其它烷基酮 (n,π态 …     

Features of Reactions of Some 1-Arylaminomethylisatins with Girard’s Reagent T

Depending on the structure of the substituent at the endocyclic nitrogen atom, the reactions of aminomethylisatins with the Girard’s reagent T can proceed both with the elimination of the aminomethyl group and with its retention resulting in the formation of the corresponding positively charged isatin-3-acylhydrazones.     

S-Adenosyl-L-methionine ameliorates TNF��-induced insulin resistance in 3T3-L1 adipocytes

An association between inflammatory processes and the pathogenesis of insulin resistance has been increasingly suggested. The IκB kinase-β (IKK-β)/ nuclear factor-κB (NF-κB) pathway is a molecular mediator of insulin resistance. S-Adenosyl-L-methionine (SAM) has both antioxidative and anti-inflammatory properties. We investigated the effects of SAM on the glucose transport and insulin signaling impaired by the tumor necrosis factor α (TNFα) in 3T3-L1 adipocytes. SAM partially reversed the basal and insulin stimulated glucose transport, which was impaired by TNFα. The TNFα-induced suppression of the tyrosine phosphorylation of the insulin receptor substrate-1 (IRS-1) and Akt in 3T3-L1 adipocytes was also reversed by SAM. In addition, SAM significantly attenuated the TNFα-induced degradation of IκB-α and NF-κB activation. Interestingly, SAM directly inhibited the kinase activity of IKK-β in vitro. These results suggest that SAM can alleviate TNFα mediated-insulin resistance by inhibiting the IKK-β/NF-κB pathway and thus can have a beneficial role in the treatment of type 2 diabetes mellitus.     

Moisture absorption and diffusion in an underfill encapsulant at T > T g and T < T g

Moisture absorption and diffusion behavior of an underfill material used for electronic packaging with a glass transition temperature (T _g) slightly above room temperature have been investigated by the sorption thermogravimetric analysis technique. It has been found that moisture diffusion in this material follows the Fick’s diffusion model, and moisture absorption–desorption is reversible and repeatable. Based on moisture-induced mass gain versus time curve, the diffusion constant can be determined. It was found that below T _g, moisture diffusivity exhibits an Arrhenius temperature dependence, which changes to a different Arrhenius temperature dependence as the temperature increases to T > T _g. The change in diffusivity from T < T _g to T > T _g is accompanied by a significant decrease in the energy barrier for moisture diffusion. Results shed light on the change in moisture diffusion in polymer-based materials in the glassy and the rubbery state.     

1O～3O T恒定磁场下碱金属原子的边界轮廓

孤立原子是具有球对称性的.如果将孤立原子置于磁场中,原子的边界半径必然会发生变化.根据原子边界轮廓理论模型,研究和计算了在10～30 T磁场强度下碱金属原子的边界轮廓,可供有关参考.     

用13C的NMR T1研究苯环上甲基的内旋转

提出了通过对样品进行邻位取代和间位取代以从实验上测定自旋-内旋转弛豫速率的处理方法.在28-90℃的温度范围内测量了邻二甲苯和间二甲苯的甲基碳的T₁和NOE因子.分离得间二甲苯上甲基碳的自旋-内旋转弛豫速率和自旋-整体旋转弛豫速率,并计算得甲基的内旋转速率.     

Calculation of the Integral ∫T0T′mexp(–E/RT′)T′

A technique has been developed for the calculation of the ∫^T ₀ T′^mexp(–E/RT′)T′. The accuracy of the method is tested by comparing its predictions with numerical results and those of a method due to Quanyin and Su. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of N1-Substituted-3-aryl-4-alkyl-4, 5-dihydro-1H-1-pyra-zolethiocarboxamide as Novel Small Molecule Inhibitors of Cysteine Protease of T.cruzi

It has been reported that the pyrazoline scaffold has activity against a broad range of therapeutic targets (e.g antibacterial、antiviral、anti-inflammatary )1,2. In our previous studies of the small molecule inhibitors of cysteine protease of T.cruzi (cruzain), the compounds, 1-(3-bromopropiophenone)-4-subsituted-thiosemicarbazonesVII, have been designed and tested both in vitro as potential antitrypanosomal agents and in the cell culture assay against T. cruzi (the causative agent of Chag…     

非晶态镍钴配合物与1T相二硫化钼复合材料的合成及其电化学全解水性能研究

正氢能源是一种重要的清洁能源。目前,电解水制氢因其工艺简单、产品纯度高、无污染和原料来源经济等特点获得了众多研究者的青睐1。对于电解水而言,如何设计和制备更加高效的催化材料,进一步减小过电位、降低能耗,是该领域     

多维微正则蒙特卡罗方法计算异氰酸S0→T1系间窜跃速率

推导了通用的坐标空间多维蒙特卡罗微正则非绝热速率计算公式,并应用于计算异氰酸基5（S0）到第一激发三态（T1）的系间窜跃（ISC）速率．在CCSD水平上构建了一,二,三维势能面用于蒙特卡罗抽样．计算所得S0→T1 ISC速率与实验符合较好,因此可以预期多维蒙特卡罗微正则非绝热速率理论将成为计算多原子分子非绝热反应速率的有效手段之一．     

Poly(ε-caprolactone)-banded spherulites and interaction with MC3T3-E1 cells

We report that protein adsorption, cell attachment, and cell proliferation were enhanced on spherulites-roughened polymer surfaces. Banded spherulites with concentric alternating succession of ridges and valleys were observed on spin-coated thin films of poly(ε-caprolactone) (PCL) and two series of PCL binary homoblends composed of high- and low-molecular-weight components when they were isothermally crystallized at 25-52 °C. Their thermal properties, crystallization kinetics, and surface morphology were examined. The melting temperature (T(m)), crystallinity (χ(c)), crystallization rate, and spherulitic patterns showed strong dependence on the crystallization temperature (T(c)) and the blend composition. The surface roughness of the spherulites was higher when T(c) was higher; thus, the larger surface area formed in banded spherulites could adsorb more serum proteins from cell culture media. In vitro mouse preosteoblastic MC3T3-E1 cell attachment, proliferation, and nuclear localization were assessed on the hot-compressed flat disks and spherulites-roughened films of the high-molecular-weight PCL and one of its homoblends. The number of attached MC3T3-E1 cells and the proliferation rate were greater on the rougher surfaces than those on the flat ones. It is interesting to note that cell nuclei were preferentially, though not absolutely, located in or close to the valleys of the banded spherulites. The percentage of cell nuclei in the valleys was higher than 78% when the ridge height and adjacent ridge distance were ~350 and ~35 nm, respectively. This preference was weaker when the ridge height was lower or at a higher cell density. These results suggest that isothermal crystallization of semicrystalline polymers can be an effective thermal treatment method to achieve controllable surface roughness and pattern for regulating cell behaviors in tissue-engineering applications.