An investigation of nonadiabatic interactions in Cl(2Pj) + D2 via crossed-molecular-beam scattering

We have determined limits on the cross section for both electronically nonadiabatic excitation and quenching in the Cl((2)P(j)) + D(2) system. Our experiment incorporates crossed-molecular-beam scattering with state-selective Cl((2)P(12,32)) detection and velocity-mapped ion imaging. By colliding atomic chlorine with D(2), we address the propensity for collisions that result in a change of the spin-orbit level of atomic chlorine either through electronically nonadiabatic spin-orbit excitation Cl((2)P(32)) + D(2)-->Cl(*)((2)P(12)) + D(2) or through electronically nonadiabatic spin-orbit quenching Cl(*)((2)P(12)) + D(2)-->Cl((2)P(32)) + D(2). In the first part of this report, we estimate an upper limit for the electronically nonadiabatic spin-orbit excitation cross section at a collision energy of 5.3 kcal/mol, which lies above the energy of the reaction barrier (4.9 kcal/mol). Our analysis and simulation of the experimental data determine an upper limit for the excitation cross section as sigma(NA)< or =0.012 A(2). In the second part of this paper we investigate the propensity for electronically nonadiabatic spin-orbit quenching of Cl(*) following a collision with D(2) or He. We perform these experiments at collision energies above and below the energy of the reaction barrier. By comparing the amount of scattered Cl(*) in our images to the amount of Cl(*) lost from the atomic beam we obtain the maximum cross section for electronically nonadiabatic quenching as sigma(NA)< or =15(-15) (+44) A(2) for a collision energy of 7.6 kcal/mol. Our experiments show the probability for electronically nonadiabatic quenching in Cl(*) + D(2) to be indistinguishable to that for the kinematically identical system of Cl(*) + He.     

Vitamin D

Ohne Zusammenfassung     

新型碳苷糖类维生素D_2衍生物的合成

以D-葡萄糖为原料,经碳苷化反应,酰化反应和脯氨酸-DIPEA催化的aldol反应制得2个碳苷糖[1-(4'-羟基苯基)-4-C-β-四乙酰基葡萄糖基-3-烯-2-酮(5a)和1-(3-羟基苯基)-4-C-β-四乙酰基葡萄糖基-3-烯-2-酮(5b)];5与琥珀酸维生素D2经Steglich酯化反应合成了2个新型碳苷糖类维生素D2衍生物,其结构经1H NMR,13C NMR和HR-ESI-MS表征。     

Phyllohydroquinone (Vitamin K1 H2) and Phylloquinone (Vitamin K1): Purification and Spectral Analysis

Abstract

Simple procedures for the preparation of pure phyllohydroquinone and phylloquinone are described. Phylloquinone is reduced by sodium dithionite and the reduced vitamin is purified by reverse phase high performance liquid chromatography. The essential spectral properties of the pure vitamins in ethanol and methanol are cited. The data provide a convenient spectral method for the accurate determination of the absolute concentrations of the oxidized and reduced vitamins and the rates of oxidation of the reduced vitamin. Pure, dry phyllohydroquinone may be safely stored at -70[ddot]C under nitrogen for a period of months. The stability of Phyllohydroquinone in methanol at 25.0 ± 0.1[ddot]C is also reported.     

HPLC-APCI(+)-MS/MS测定乳制品中的维生素D_2及D_3

建立了一种高效液相色谱-大气压化学电离串联四极杆质谱,正离子监测模式下(HPLC-APCI(+)-MS/MS)测定乳制品中维生素D2和D3的方法。样品经皂化后,用石油醚提取,提取液经无水硫酸钠干燥,在氮气保护下旋转蒸发浓缩至10 m L以下,氮气吹干,用10 m L甲醇溶解后,经ACQUITY UPLC BEH C18色谱柱(1.7μm,2.1 mm×100 mm)分离,甲醇-水(95∶5)洗脱,多反应监测模式测定。维生素D2和D3在0.01~0.2 mg/L范围内呈良好的线性关系,相关系数(r2)分别为0.998 7和0.999 1,方法回收率为83.0%~99.4%,相对标准偏差(RSD)为2.0%~8.3%。     

Magnetic structure of Ni(DCOO)2(D2O)2

Ni(HCOO)(2)(H(2)O)(2) is a structurally simple coordination polymer showing interesting magnetic phase transitions at low temperature (<16K). Previously published studies of these phase transitions have yielded inconsistent results, questioning the correctness of the published magnetic structure. Here heat capacity and magnetic susceptibility of a fully, a partly and a non-deuterated sample were measured, and they all exhibit magnetic phase transitions around 3 and 15 K. Neutron powder diffraction data was collected on the fully deuterated sample at various temperatures between 1.5 and 25 K. A magnetic model was refined against the neutron diffraction data using a spin system composed of two canted antiferromagnetic sublattices. The magnetic moments of the two sublattices show different magnitude, 1.7 μ(B) and 1.3 μ(B), and the temperature dependence of the magnetic sublattices is quite different. One of the sublattices shows the expected temperature behavior of an antiferromagnetic compound whereas the other sublattice follows a Brillouin like function with a slowly increasing magnetization below the Ne?el temperature.     

二维相关振动光谱技术

从发展历史、计算方程、性质规则等方面系统地介绍了近年来发展起来的二维相关光谱技术.结合各种常见的一维振动光谱, 如红外、拉曼、荧光、近红外-红外等光谱举例阐述了二维振动光谱的优势及其普适性.介绍了在广义二维相关光谱理论上最新延伸发展起来的二维样品-样品相关技术和二维杂化相关技术的基本理论, 并将之与传统的二维变量-变量相关技术(广义二维相关光谱)进行了比较.     

Infrared spectra of ethylene clusters: (C2D4)2 and (C2D4)3

Spectra of ethylene dimers and trimers are studied in the ν(11) fundamental band region of C(2)D(4) (≈2200 cm(-1)) using a tuneable quantum cascade laser to probe a pulsed supersonic slit jet expansion. The dimer spectrum is that of a prolate symmetric top perpendicular band, with a distinctive appearance because the A rotational constant is almost exactly equal to six times the B constant. The analysis supports the previously determined cross-shaped dimer structure with D(2d) symmetry. An ethylene trimer has not previously been observed with rotational resolution. The spectrum is that of an oblate symmetric top parallel band. It leads to a proposed trimer structure which is barrel shaped and has C(3h) or C(3) symmetry, with the ethylene monomer C-C axes approximately aligned along the trimer symmetry axis.     

Self-assembled 2D supramolecular networks of copper(I) carborane complexes through C-H..H-B dihydrogen bonding interactions

Three dinuclear copper(i) complexes with the formula [Cu(2)(mu-X)(2)(1,2-(P(i)Pr(2))(2)-1,2-C(2)B(10)H(10))(2)] (X = Cl (), Br (), I ()) containing the closo carborane diphosphine ligand 1,2-(P(i)Pr(2))(2)-1,2-C(2)B(10)H(10) have been prepared and characterized by elemental analysis, FT-IR and X-ray structure determination. The X-ray structure analyses revealed that the three complexes were isostructural and crystallized in the monoclinic system and space group C2/m. The carborane cage ligand was coordinated bidentately to the Cu(i) center through its two phosphorus atoms, and the coordination geometry around each copper atom was distorted tetrahedral. Two halogen atoms bridged the metal centers forming a dimer structure [Cu(2)(mu-X)(2)(1,2-(P(i)Pr(2))(2)-1,2-C(2)B(10)H(10))(2)], which were linked into 2D supramolecular networks through novel C-HH-B dihydrogen bonding interactions.     

Functionalization at C-12 of 1alpha,25-dihydroxyvitamin D(3) strongly modulates the affinity for the vitamin D receptor (VDR)

The first synthesis of analogues of the natural hormone 1alpha,25-dihydroxyvitamin D(3) (1a) with substituents at C-12 is reported. The following are the relative affinities of the novel compounds for the vitamin D receptor (VDR) compared to that of 1a (100%): 1alpha,12alpha,25-(OH)(3)-D(3) (1b, 1%), 1alpha,25-(OH)(2)-12-methylene-D(3) (1c, 50%), and 1alpha,25-(OH)(2)-12beta-methyl-D(3) (1d, 440%). [structure: see text]     

Dispersion interactions between neighboring Bi atoms in (BiH3)2 and Te(BiR2)2

Triggered by the observation of a short Bi⋯Bi distance and a Bi Te Bi bond angle of only 86.6° in the crystal structure of bis(diethylbismuthanyl)tellurane quantum chemical computations on interactions between neighboring Bi atoms in Te(BiR₂)₂ molecules (R = H, Me, Et) and in (BiH₃)₂ were undertaken. Bi⋯Bi distances atoms were found to significantly shorten upon inclusion of the d shells of the heavy metal atoms into the electron correlation treatment, and it was confirmed that interaction energies from spin component‐scaled second‐order Møller–Plesset theory (SCS‐MP2) agree well with coupled‐cluster singles and doubles theory including perturbative triples (CCSD(T)). Density functional theory‐based symmetry‐adapted perturbation theory (DFT‐SAPT) was used to study the anisotropy of the interplay of dispersion attraction and steric repulsion between the Bi atoms. Finally, geometries and relative stabilities of syn–syn and syn–anti conformers of Te(BiR₂)₂ (R = H, Me, Et) and interconversion barriers between them were computed. © 2018 Wiley Periodicals, Inc.     

High translational energy release in H2 (D2) associative desorption from H (D) chemisorbed on C(0001)

Highly energetic translational energy distributions are reported for hydrogen and deuterium molecules desorbing associatively from the atomic chemisorption states on highly oriented pyrolytic graphite (HOPG). Laser assisted associative desorption is used to measure the time of flight of molecules desorbing from a hydrogen (deuterium) saturated HOPG surface produced by atomic exposure from a thermal atom source at around 2100 K. The translational energy distributions normal to the surface are very broad, from approximately 0.5 to approximately 3 eV, with a peak at approximately 1.3 eV. The highest translational energy measured is close to the theoretically predicted barrier height. The angular distribution of the desorbing molecules is sharply peaked along the surface normal and is consistent with thermal broadening contributing to energy release parallel to the surface. All results are in qualitative agreement with recent density functional theory calculations suggesting a lowest energy para-type dimer recombination path.     

D2HEDTPA和D2EHPA萃取汞(II)的研究

The extration of Hg2+ from HNO3 solution with (D2EHPA) and bis(2-ethylhexyl dithiophosphate (D2EHDTPA) was studied. The composition of extracted complex was determine by saturation and mol. ratio methods. The bonding of the extracted species is discussed on the basis of IR and NMR data. EHMO calcns. show that the extration capacities of the 2 extractants for Hg2+ are quite different.     

Assessing 2D electrophoretic mobility spectroscopy (2D MOSY) for analytical applications

Electrophoretic displacement of charged entity phase modulates the spectrum acquired in electrophoretic NMR experiments, and this modulation can be presented via 2D FT as 2D mobility spectroscopy (MOSY) spectra. We compare in various mixed solutions the chemical selectivity provided by 2D MOSY spectra with that provided by 2D diffusion‐ordered spectroscopy (DOSY) spectra and demonstrate, under the conditions explored, a superior performance of the former method. 2D MOSY compares also favourably with closely related LC‐NMR methods. The shape of 2D MOSY spectra in complex mixtures is strongly modulated by the pH of the sample, a feature that has potential for areas such as in drug discovery and metabolomics. Copyright © 2016 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.     

Sunbeds as Vitamin D Sources

The objectives of this work were: (1) To determine whether repeated exposures to small doses from a commercial sun bed (Wolff Solarium Super Plus 100 W) over 5 weeks gave less vitamin D than repeated exposures to twice as large, but still nonerythemogenic, doses. (2) To investigate whether the contribution to the vitamin D status from such sessions of exposures was dependent on the baseline status before the start of the sessions. (3) To determine the decay rate of the induced increment of vitamin D. The sun bed sessions raised the 25-hydroxyvitamin D levels from typical winter values to typical summer values. The mean value after exposure being 80 n m (±14) and the increase being 15 n m on average. Persons with the lowest initial levels got the largest increase. The level in this group was back to the pre-exposure level after 2–4 weeks. To maintain a summer level through the winter, when no vitamin D is produced by the sun in northern countries, one should consider increasing the recommended intake of vitamin D intake significantly, or encouraging the population to get moderate, nonerythemal sun bed exposures.     

Vitamin D and Skin Cancer

Vitamin D signaling plays a key role in many important processes, including cellular proliferation, differentiation and apoptosis, immune regulation, hormone secretion and skeletal health. Furthermore, vitamin D production and supplementation have been shown to exert protective effects via an unknown signaling mechanism involving the vitamin D receptor (VDR) in several diseases and cancer types, including skin cancer. With over 3.5 million new diagnoses in 2 million patients annually, skin cancer is the most common cancer type in the United States. While ultraviolet B (UVB) radiation is the main etiologic factor for nonmelanoma skin cancer (NMSC), UVB also induces cutaneous vitamin D production. This paradox has been the subject of contradictory findings in the literature in regards to amount of sun exposure necessary for appropriate vitamin D production, as well as any beneficial or detrimental effects of vitamin D supplementation for disease prevention. Further clinical and epidemiological studies are necessary to elucidate the role of vitamin D in skin carcinogenesis.     

Polyfunctional Two- (2D) and Three- (3D) Dimensional Oxalate Bridged Bimetallic Magnets

Summary.  We report major results concerning polyfunctional two- (2D) and three- (3D) dimensional oxalate bridged bimetallic magnets. As a consequence of their specific organisation they are composed of an anionic sub-lattice and a cationic counter-part. These bimetallic polymers can accommodate various counter-cations possessing specific physical properties in addition to the magnetic ones resulting from the interactions between the metallic ions in the anionic sub-lattice. Thus, molecular magnets possessing paramagnetic, conductive and optical properties are presented in this review. Corresponding author. E-mail: train@ccr.jussieu.fr Received April 11, 2002; accepted May 27, 2002     

Zur Bestimmung von Vitamin D

Ohne Zusammenfassung