Spin-glass like behaviors in cubic VOx

Magnetic susceptibility (d.c.) measurements were performed on the well characterized cubic VO_x(1.10 ?x?1.28). A sharp cusp-like peak in χ(T) curve was analyzed in terms of spin-glass behavior and the spin-glass order parameter, q(T) was extracted from χ cusp using Sherrington-Kirkpatrick model. This analysis as well as the other characteristic behaviors strongly suggests the possible existence of spin-glass state in this material.     

Spectroscopic study on interaction of nucleic acid base with tryptophan-containing tripeptides: acetyl-Trp-X-Trp-NHCH3 (X = Gly, Asn, Asp, Gln and Glu).

As part of a series of peptides designed to have binding ability selective for each of the nucleic acid bases, five tripeptides consisting of N-acetyl-Trp-X-Trp-NHCH3 (X = Gly, Asn, Asp, Gln and Glu) were synthesized, and their abilities to form complexes with four different nucleotides were examined by the fluorescence and phase distribution methods. The association constants obtained indicated that, depending on the sort of X residue, the peptides showed a variation in their interaction with guanosine monophosphate (GMP), while no noticeable selectivity was observed for other nucleotides adenosine monophosphate (AMP), uridine monophosphate (UMP) and cytidine monophosphate (CMP). The binding mode of N-acetyl-Trp-Asp-Trp-NHCH3 for the guanine base was further investigated using the proton nuclear magnetic resonance (1H-NMR) method. The mode was suggested to involve intimate cooperation of (1) the hydrogen bond formation between the carboxyl group of the Asp side chain and the guanine C2-amino group, and (2) the stacking interaction of the base with two terminal Trp residues of the peptide. Such interaction was strengthened by the protonation of the guanine base. A tentative binding mode is proposed based on these results.     

氢分子电子态b1Пu及其振动态的微分截面和振子强度

在电子入射能量300 eV条件下,测量了氮分子在不同散射角下的12—14 eV能区的能量损失谱,散射角范围为2.75°—10.25°。得到了电子态b¹∏_u振动能级v’=1—4的散射微分截面和广义振子强度,并通过外推k~2至零的方法得到了b¹∏_u及其振动能级v’=1—4的散射微分截面和广义振子强度,并通过外推K~2主零的方法得到了b¹∏_u及其振动能级v’=1—4的光学振子强度。所得结果与已发的实验数据和理论结果作了比较     

The intralayer order-disorder transition in monoclinic Cr3±xSe4

The Cr_3±xSe₄ shows an order-disorder transition from the monoclinic Cr₃Se₄ type to the CdI₂-type structure. This transition originates in the intralayer disordering of metal vacancies in the alternate partially filled metal layers along thec axis. The transition is reversible and of first order. The transition temperature vs composition curve has a maximum (～900°C) at a stoichiometric composition of Cr₃Se₄. A statistical treatment of this phenomenon was attempted via the Bragg-Williams approximation.     

An on-line ion trap for unstable nuclei at INS

An on-line ion trap system is under construction at INS in order to study properties of the trapped unstable nuclei produced by a cyclotron beam. Among several subjects on the system, development of a direct trapping method for unstable nuclear ions from a recoil separator is taken to be of first priority. We have successfully developed a new ion cooling device for this purpose using an ion-guide followed by an RF multipole ion beam guide.On leave from the Institute of Atomic Energy, Academia Cinica, Shanghai, P.R. China     

Study on retention behavior of cyclic siloxanes by high resolution pyrolysis-gas chromatography with a fused silica capillary column

The general gas chromatographic retention behavior of cyclic methylsiloxanes partially substituted with phenyl or 2-cyanoethyl groups has been systematically studied, with pyrolysis-gas chromatography being utilized to form the cyclic siloxanes from the corresponding polysiloxanes at a temperature of 600°C. Kovats retention indices (KI) were determined for the cyclic siloxanes by use of the retention data of the pyrolyzates from polyethylene as standards. The effect of phenyl and 2-cyanoethyl substituents in the cyclic siloxanes on retention behavior has also been considered.     

Determination of sulfur-containing amino acid residues in proteins by pyrolysis-gas chromatography with flame photometric detection

Summary A new method for the determination of sulfur-containing amino acid residues, cysteine (Cys) and methionine (Met) in proteins has been developed with pyrolysis-gas chromatography. Characteristic sulfur compounds among the complicated pyrolysis products formed from protein samples were separated by using a high resolution fused silica capillary column and selectively detected by flame photometric detector (FPD). In order to improve the reproducibility, an internal standard substance, benzothiophene, was pyrolyzed at 600 °C together with the protein samples. Thus the observed pyrograms were interpreted in terms of the compositional analysis. On the basis of the relative peak intensities of CH₃SH and H₂S, the simultaneous determinations of Cys and Met residues in various enzyme proteins were successfully carried out with 10–12% and 5–6% of relative standard deviations, respectively.

---

Bestimmung von schwefelhaltigen Aminosäureresten in Proteinen durch Pyrolyse-GC mit flammenphotometrischer Detektion