基于竞争配位的Ca2+特异性响应1H/19F磁共振成像分子探针

合成了一种含~(19)F的Mn~(2+)配合物3,12-二(2-氧代-2-((2,2,2-三氟乙基)氨基)乙基)-6,9-二氧杂-3,12-二氮杂十四烷酸锰(Ⅱ)(Mn(Ⅱ)-L,1),可实现对Ca~(2+)特异响应的~1H/~(19)F磁共振成像分析。~(19)F核在近距离的顺磁性Mn~(2+)影响下产生了顺磁弛豫增强作用,使~(19)F的横向弛豫时间T_2急剧缩短而磁共振信号锐减。当有Ca~(2+)存在时,与配体L的竞争配位使得~(19)F远离Mn~(2+)离子,从而~(19)F磁共振信号得到恢复。同时,由于Mn~(2+)离子从配合态变为游离态,水配位数增加使得其对~1H的纵向弛豫时间T_1弛豫性能增加,从而~1H磁共振成像信号也增强。相关实验的结果证实了该配合物是一种能对Ca~(2+)特异性响应的~1H/~(19)F磁共振成像探针。     

A comprehensive in Silico analysis of the functional and structural impact of single nucleotide polymorphisms (SNPs) in the human IL-33 gene

Interleukin 33 (IL-33) is the latest member of the IL-1 cytokine family, which plays both pro - and anti-inflammatory functions. Numerous Single-nucleotide polymorphisms (SNPs) in the IL-33 gene have been recognized to be associated with a vast variety of inflammatory disorders. SNPs associated studies have become a crucial approach in uncovering the genetic background of human diseases. However, distinguishing the functional SNPs in a disease-related gene from a pool of both functional and neutral SNPs is a major challenge and needs multiple experiments of hundreds or thousands of SNPs in candidate genes. This study aimed to identify the possible deleterious SNPs in the IL-33 gene using bioinformatics predictive tools. The nonsynonymous SNPs (nsSNPs) were analyzed by SIFT, PolyPhen, PROVEAN, SNP&GO, MutPred, SNAP, PhD SNP, and I-Mutant tools. The Non-coding SNPs (ncSNPs) were also analyzed by SNPinfo and RegulomeDB tools. In conclusion, our in-silico analysis predicted 5 nsSNPs and 22 ncSNPs as potential candidates in the IL-33 gene for future genetic association studies.     

A crossed molecular beam study of the chemiluminescent reaction Xe(3P2,0) + BrCN → Xe(1S0) + Br + CN(B2Σ+)

The chemiluminescent interaction of Xe(³P_2,0) and BrCN has been studied under crosscd-beam conditions at collision energies ranging up to 70 kj mol^?1. The CN(B → X) fluorescence spectrum, the excitation function for its production and the fluorescence polarisation - or rather its absence - have been determined. The results can be explained by a two-stage harpooning mechanism involving an inert-gas cyanide (Xe⁺CN^?)¹ intermediate but not by a “sensitisation” mechanism proceeding through electronic energy transfer.     

M(bpy)2+3(M=Fe,Ru,Os)电子结构与相关性质

报导了对配合物Ｍ（ｂｐｙ）＾２＋３（Ｍ＝Ｆｅ,Ｒｕ,Ｏｓ）的量子化学密度泛函法研究的结果。Ｂ３ＬＹＰ／ＬａｎＬ２ＤＺ方法与基组的水平上进行计算,探讨Ｍ（ｂｐｙ）＾２＋３电子结构特征及相关性质,特别是中心原子对配合物的配位键长、光谱性质,电荷布局及化学稳定性等的影响规律,为该类配合物的合成,为分析光、电、催化作用机理提供理论参考。     

CONFORMATIONAL CHARACTERISTICS OF POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID)

A full-relaxation optimization of molecule and the Dreiding force field are employed toobtain the geometry parameters and the conformational energy surfaces of meso or racemicdyad of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA). Three differentcarbonyl-bond orientations of side-groups resulted in the differences in depth of potentialwells in their energetic contours for a meso or a racemic dyad. These discrepancies areinterpreted as a result of various fine structures corresponding to grid search conformationsas well as thereby different interactions. The analysis on the most stable conformationsof PMAA confirmed that the ester groups are nearly perpendicular to the plane definedby the two adjacent skeletal bonds but may possibly change their relative orientations tomeet the requirement of lower energy during the conformational state transition. For eachpolyme, two global energy maps of a meso and a racemic dyad were finally constructedfrom the superposition of energy data for the three kinds of side-group orientations by theBoltzmann factors. From an ensemble average, the proposed scheme with three rotationalisomeric states (RIS) allowed us to access the experimentally unperturbed dimensions ofPAA chain via the configurational statistical mechanics. Although the calculation wasbased on the short-range, local interactions, it was interested to note that the experimentalcharacteristic ratios just fell within the range calculated for atactic chains.     

The assessment of miscibility and morphology of poly(ε-caprolactone) and poly(para-chlorostyrene) blends

The miscibility and morphology of poly(ε-caprolactone) (PCl) and poly(para-chlorostyrene) (PpClS) blend were investigated by using thermal analysis, morphological analysis, viscometry, and the study of melting point depression. A single glass transition temperature was observed by differential scanning calorimetry (DSC) for PCl/PpClS blends in the whole compositional range (0/100, 25/75, 50/50, 62.5/37.5, 75/25, 90/10). Morphology of the polymers and their blends was studied by scanning electron microscopy (SEM). The Fourier transform infrared spectra of the samples were obtained by spectrometer. Up to 12 cm⁻¹ shifts in carbonyl stretching band of PCl was detected in the spectra of PpClS rich blends. The viscosity of PCl, PpClS and their blends has also been studied to investigate the miscibility according the miscibility criteria Δb, and Δ[η]. Using this data, the interaction parameters α and μ, based on the Chee and Sun et al. approaches were determined. These criteria indicated that the blend is miscible in all proportions up to 90% of PCl content in the blends. The melting point depression of PCl in the blends was examined to obtain the interaction parameter, χ₁₂ for this system. The parameter, χ₁₂ was found to be composition dependent. Negative values of the obtained interaction parameter also support the miscibility of this system up to the 90% PCl in the blend.     

Electrochemiluminescence from Ru(bpy)3 immobilized in poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)-poly(vinyl alcohol) composite films

Electrochemical behavior and electrogenerated chemiluminescence (ECL) of tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) immobilized in poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)-poly(vinyl alcohol) (PEDOT/PSS-PVA) composite films via ion-exchange have been investigated with tripropylamine (TPA) as the co-reactant at a glassy carbon electrode. The immobilized Ru(bpy)₃²⁺ performed a surface-controlled electrode reaction. The Ru(bpy)₃²⁺ modified electrode showed a fast ECL response to TPA, and was used for the ECL detection of TPA with high sensitivity. The ECL intensity was linearly related to concentrations of TPA over the range from 0.50 μmol L⁻¹ to 0.80 mmol L⁻¹, and the detection limit was 0.10 μmol L⁻¹ (S/N = 3). The as-prepared electrode exhibited good precision and long-term stability for TPA determination.     

双水杨醛邻苯二胺柱前衍生-高效液相色谱法测定茶叶中的Pb~(2+)

建立了利用双水杨醛邻苯二胺希夫碱(SALOPHEN)作为衍生剂结合高效液相色谱(HPLC)测定茶叶中Pb~(2+)含量的方法。Hypersil ODS2 C18反相色谱柱(250 mm×4.6 mm,5μm)为固定相,甲醇-水(80∶20,v/v)为流动相,检测波长为226 nm,反应体系pH为10.0。结果表明,样品中Pb~(2+)的线性范围为0.1~30 mg/L,线性相关系数为0.998 8,检出限为0.01 mg/L,加标回收率为91.87%~96.96%。该方法具有较高的灵敏度和稳定性,适用于茶叶中Pb~(2+)的检测。     

STUDY ON FLUORESCENCE BEHAVIOUR OF EU~(3+) CONTAINING POLY(METHYL METHACRYLATE)

Fluorimetry has been used to characterize ionomers synthesized by copolymerization ofmethyl mehacrylate, methacrylic acid and europium methacrylate (EMA). Under excita-tion of UV light at 375 nm no seif-quenching was found in fluorescence of EMA containingionomers at 615nm within the concentration range of 1.6×10~(-2) to 11.49×10~(-2) mol%.This means that the distance between two Eu~(3+) ions is larger than 5nm. In the sameconcentration range seif-quenching took place in europium octanoate (EOA) containingpoly(methyl methacrylate) in which EOA was doped as an additive.     

Pt(PPh3)2-η2C60络合物的分子轨道研究

近年来,自Kratschmer 等人采用并不复杂的方法就能制备出宏观量的C_(60),人们对它的兴趣也从结构的研究逐渐转向化学性质的研究.C_(60)是目前自然界已知对称性最高的球状分子,每个C 原子都以接近sp~2杂化轨道和相邻的三个C 原子相联.C_(60)的NMR 化学位移以及闭壳层的电子结构和较宽的HOMO-LUMO 间隙,都说明它具有典型的芳香化合物——苯的某些特性.另外,掺杂(碱金属元素)后,它具有的导电性又表现出石墨具有的某些特点.     

EFFECT OF SOLVENT COMPOSITION ON THE SULFONATION DEGREE OF POLY(PHENYLENE OXIDE) (PPO)

This paper investigates the possibility of attaining sulphonated poly(phenylene oxide) (SPPO) with a relativelyhigher sulfonation degree. To achieve this aim, the approach we adopt is to improve the solubility of the final product in themixed solvent so that the sulfonation may take place between the bulk solutions and PPO powders even at higher sulfonationdegree. It is shown that the addition of a proper amount of dimethyl formide (DMF) to the conventional PPO-chloroformsystem can actually enhance the sulfonation effect. The solvent composition is then correlated with the sulfonation degreebased on the solubility parameters. It is interesting to find that solubility parameters between the mixed solvent and theprecipitated products keep an approximately unchanged value at about 4.9, which is just equal to that when pure chloroformis used, though the solubility parameters of both solvents increase with the content of DMF in solution. This may be the mainreason why the addition of DMF can reduce the precipitation and improve the ion exchange capacity (IEC) of SPPOpolymer.     

COMPUTER SIMULATIONS ON UNPERTURBED CONFIGURATIONAL DIMENSIONS OF POLY (METHYL ACRYLATE)

A full-relaxation optimization of molecule and the popular MM2 force field are em-ployed to obtain the geometry parameters and the conformational energy surface of a mesoor a racemic dyad of poly(methyl acrylate) (PMA) with a specified carbonyl-bond orien-tation in side-groups. It is found that the conformational energy maps calculated hereconsiderably differ from those calculated with the rigid molecular model as reported in theearlier studies. The g~- state cannot be omitted in the obtained contour maps. Two impor-tant conformers tg~- and g~(-t) with energy minima were newly detected for a racemic dyad.The analysis on the conformations with energy minima confirmed that the ester groupsare not always perpendicular to the plane defined by the two adjacent skeletal bonds andmay change their relative orientations to meet the requirement of lower energies duringthe conformational state transition. Instead of the early way of adjusting the interactionenergy parameters to fit the experimental data, we attempt to predict unperturbed chaindimensions via the reliable force field and the configurational statistical mechanics. Theproposed scheme with three rotational states identified from the contour maps allowed usto satisfactorily reproduce the experimental dimensions of random PMA chains.     

Low coercive field and conducting nanocomposite formed by Fe3O4 and poly(thiophene)

Magnetite and poly(thiophene) composites have been produced by in situ monomer oxidation. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) confirmed the presence of Fe₃O₄ as particle agglomerates ranging from 15 to ca. 54 nm in size. Transmission electron micrographs (TEMs) revealed a face-to-face structure in both the pure magnetite and the nanocomposite. Typical superparamagnetic (ferrimagnetic) curves have been observed, whereas the relatively weak magnetic field employed in measurement, 200 Oe, was sufficient to split the curves completely. Zero field cooling (ZFC) and field cooling (FC) curves coincide only above room temperature, indicating that the characteristic blocking temperature (T_B) for superparamagnetic particles in this assembly is above room temperature.     

Miscibility and ferroelectric behavior in blends of poly(vinylidene fluoride/trifluoroethylene) and poly(vinyl acetate)

The blend system containing a poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer (68/32 mol %) and poly(vinyl acetate) (PVAc) was miscible from the results of differential scanning calorimetry (DSC) studies that exhibit the presence of a single, composition‐dependent glass transition temperature (T_g) and a strong melting point depression for the semicrystalline P(VDF/TrFE) component. However, differences between the DSC and dielectric measurements, which showed a separate P(VDF/TrFE) T_g peak, suggests that the P(VDF/TrFE)/PVAc blends are actually partially miscible. Because of the lower dielectric constant of PVAc and the reduced sample crystallinity caused by the addition of PVAc, both the dielectric constant and the remanent polarization of the copolymer blends decrease with increasing PVAc content. The presence of a small amount of PVAc stabilized the anomalous ferroelectric behavior of ice–water‐quenched P(VDF/TrFE), and the blend portrayed normal polarization reversal behavior after adding only 1 wt % PVAc. The piezoelectric response suggests small changes with an increasing number of poling cycles. It is believed that PVAc affects the D‐E hysteresis behavior at the interface between crystalline and amorphous phases, although much work remains to be done to confirm this hypothesis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 927–935, 2003     

A facile approach to preparation of long-chain-branched poly(p-dioxanone)

Long-chain-branched poly(p-dioxanone)s (LCB-PPDOs) with different branch densities were prepared via the chain-extending reaction of hydroxyl group terminated linear bi-functional PPDO (2a-PPDO) and star-like tri-functional PPDO (3a-PPDO) prepolymers, which were synthesized by the ring-opening polymerization of p-dioxanone (PDO) using 1,4-butanediol (BD) and trimethylolpropane (TMP) as multi-functional initiators, respectively. The undesirable gelation was successfully depressed by adjusting the chain length and feed ratio of prepolymers. The average molecular weight between branch points (M_b) and the average number of branch per 100,000 g/mol (B_n) of LCB-PPDOs were calculated from the ¹H NMR spectra. The average number of branch ranged from 0 to 6.72 branch points per 100,000 g/mol, and the number-average molecular weights between branch points ranged from 6900 to 20,500 g/mol. The results of differential scanning calorimetry (DSC) showed that the crystallization behavior of LCB-PPDOs was changed evidently with the branch density. Small-amplitude dynamic oscillatory rheometer was used to investigate the rheological properties of the melts of LCB-PPDO including zero-shear viscosity, storage modulus, relaxation times and loss angle, which largely depended on the branch density and length of LCB-PPDOs. Therefore, the rheological behaviors of PPDO can be well-controlled via synthesizing LCB-PPDOs with the desired architectures.     

Phonon dispersion and heat capacity in poly(ε-caprolactone)

Normal mode of vibration and their dispersion for poly(ε-caprolactone) (PCL) chain have been obtained by using Urey-Bradley force field and the Wilson's GF matrix method as modified by Higgs. Characteristic features of the dispersion curves such as crossing, repulsion and regions of high density-of-states have been explained. Heat capacity measurements have been interpreted and the limitations of the present work discussed.     

Cu(bpy)2+2与鸟嘌呤及鸟苷相互作用的研究

在中性磷酸盐缓溶冲液中，用电化学和荧光光谱法研究了Cu(bpy)²⁺₂与鸟嘌呤和鸟苷的相互作用。结果表明鸟嘌呤和鸟苷与Cu(bpy)²⁺₂的配位比均为1∶1，配位常数分别为4.62×10⁴ L/mol和1.96×10⁴ L/mol。紫外光谱电化学实验进一步表明，鸟嘌呤或鸟苷与Cu(bpy)²⁺₂发生了相互作用。     

An electrochemical investigation on the reduction path of the arene complexes [CpM(arene)]2+ and [(η-9-SMe2-7,8-C2B9H10)M(arene)]2+ (M=Rh, Ir)

The reduction behavior of the isoelectronic complexes [CpM^III(η⁶-C₆R₆)]²⁺ (M=Rh, Ir; R=H, Me) and [(η-9-SMe₂-7,8-C₂B₉H₁₀)M^III(η⁶-C₆R₆)]²⁺ (M=Rh, Ir; C₆R₆ = C₆H₆, C₆H₅OMe, C₆H₃Me₃) has been studied by cyclic voltammetry and controlled potential coulometry in acetonitrile and propylene carbonate at 253 and 298 K, respectively. The extent of chemical reversibility of the pertinent sequences Rh(III)/Rh(II)/Rh(I) and Ir(III)/Ir(I) is highly dependent on both the nature of the solvent and the intrinsic electronic properties of the arene substituents. The arene η⁶ coordination makes the derivatives in their lower oxidation states notably short lived, even if, in some cases, the use of propylene carbonate improves their stability or causes the increase in their lifetimes before changing the arene coordination from η⁶ to η⁴. Cations [(η-9-SMe₂-7,8-C₂B₉H₁₀)M(η⁶-C₆R₆)]²⁺ were obtained by the bromide abstraction from [(η-9-SMe₂-7,8-C₂B₉H₁₀)MBr₂]₂ with Ag⁺ in the presence of benzene and its derivatives. The structure of [(η-9-SMe₂-7,8-C₂B₉H₁₀)Ir(η⁶-C₆H₅OMe)](BF₄)₂ was determined by X-ray diffraction.     

Water sorption/desorption kinetics in poly(ethylene naphthalene-2,6-dicarboxylate) and poly(ethylene terephthalate)

Water sorption/desorption experiments were carried out on films (～ 220 μm thick) of amorphous poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) stored in ambient conditions for different periods of time (0.5-4 years) and of poly(ethylene terephthalate) (PET) with different degrees of crystalinity levels (0-29%) by means of FTIR spectroscopy. Water sorption/desorption kinetics follows Fick's law for all samples investigated. Water sorption isotherms, obtained from gravimetric methods, indicate a larger sorption capacity in the case of PEN materials. The apparent diffusion coefficients (D) are larger in the case of PET samples. The observed D values decrease with storage time (physical aging) of PEN samples and with the crystallinity of PET samples. © 1995 John Wiley & Sons, Inc.