The application of a new sampling technique using an atomizer for chemical ionization mass spectrometry to free amino acids,drug components,higher phthalates and oligomers of styrene and ethyleneglycol

A new vacuum atomizing sample introduction device was developed and applied to take stable and reproducible chemical ionization mass spectra of various involatile compounds. As examples, chemical ionization spectra of some free amino acids, drug components in a cold medicine, higher phthalates, oligomers of styrene and ethyleneglycol, etc., are presented.     

A study of deformation-produced deep levels inn-GaAs using deep level transient capacitance spectroscopy

Deformation-produced deep levels, both of electron and hole traps, have been studied using deep level transient capacitance spectroscopy (DLTS) for an undopedn-type GaAs (HB grown) compressed at 440°C. Concentrations of two grown-in electron trap levels (E _c −0.65eV andE _c −0.74eV) and one grown-in hole trap level (E _v +∼0.4eV) increase with plastic deformation, while that of a grown-in electron trap level (E _c −∼0.3eV) decreases in an early stage of deformation. While no new peak appeared in the electron trap DLTS spectrum after plastic deformation, in the hole trap DLTS spectrum a broad spectrum, seemingly composed of many peaks, newly appeared in a middle temperature range, which may be attributed to electronic energy levels of dislocations with various characters.     

Application of selective 13C?{1H} nuclear overhauser effects with low-power 1H irradiation in carbon-13 NMR spectroscopy

The feasibility of the application of selective ¹³C? {¹H} nuclear Overhauser effect (NOE) measurements to organic structural analysis in ¹³C NMR spectroscopy has been investigated at 25 MHz using citraconic anhydride and the methyl ester of pentalenolactone as model compounds. This selective ¹³C? {¹H} NOE technique with single frequency low-power ¹H irradiation should find wide application in the structural elucidation of organic compounds, especially for the reliable assignment of quaternary carbon signals.     

High momentum transfer structure factor of liquid bromine by TOF neutron diffraction

Structure factor of liquid bromine was observed by TOF neutron diffraction based on electron linac and the size of a single molecule in the liquid state was confirmed to be very close to that in the gaseous state.     

Flexible Enantiodivergent Synthesis and Biological Activity of Mannostatin Analogues, New Cyclitol Glycosidase Inhibitors

Mannostatin A (1) is a new cyclitol inhibitor of glycoprotein processing. 2-Epimannostatin A (12) and its enantiomer (13) as well as their positional isomers (14, 15) were designed for probing structure-activity relationships in this class of glycosidase inhibitors. The analogues have been synthesized from (S)-4-((tert-butyldimethylsilyl)oxy)-2-cyclopentenone by an enantiodivergent strategy in a totally stereospecific fashion. Compound 13 showed inhibition against almond beta-glucosidase and is shown to be a topographical analogue of beta-D-glucopyranoside.