Untersuchung von Mehl und Getreide

Ohne Zusammenfassung     

Derriswurzel Rotenon

Ohne Zusammenfassung     

The gene-protein database of Escherichia coli: edition 5.

The gene-protein database of Escherichia coli is both an index relating a gene to its protein product on two-dimensional gels, and a catalog of information about the function, regulation, and genetics of individual proteins obtained from two-dimensional gel analysis or collated from the literature. Edition 5 has 102 new entries--a 15% increase in the number of annotated two-dimensional gel spots. The large increase in this edition was accomplished in part by the use of a new method for expression analysis of ordered segments of the E. coli genome, which has resulted in linking 50 gel spots to their genes (or open reading frames) and another 45 to specific regions of the chromosome awaiting the availability of DNA sequence information. Communication of information from the scientific community resulted in additional identifications and regulatory information. To increase accessibility of the database it has been placed in the repository at the National Center for Biotechnology Information (NCBI) at the National Library of Medicine under the name ECO2DBASE. It will be updated twice yearly. This edition of the gene-protein database is estimated to contain entries for one-sixth of the protein-encoding genes of E. coli.     

Pulsed titration sensors: Part 1: A breath-by-breath CO2 sensor

A novel electrochemical sensor for the determination of CO₂ in expired breath is described. The sensor works by generating from the reduction of O₂ in dimethyl sulphoxide (DMSO) in a generating pulse. There is a rapid titration reaction between the and any CO₂ present. In the recovery pulse the amount of unreacted is determined. The larger the concentration of CO₂ the less is found in the recovery pulse. The solubilities and diffusion coefficients of O₂ and CO₂ in DMSO have been determined using rotating disc voltammetry and rotation speed step experiments. The stoichiometry, the product, and the rate constant of the titration reaction have been determined using ring—disc voltammetry and laser Raman spectroscopy. The operation and the effect of adventitious water on the sensor are described. Results are presented which show that the sensor can indeed measure the breath-by-breath rhythm of expired CO₂ from a human subject.     

ELECTRON SPIN ECHO ENVELOPE MODULATION OF THE TRANSIENT EPR SIGNALS OBSERVED IN PHOTOSYNTHETIC ALGAE AND CHLOROPLASTS*

Phase memory decays were obtained from the transient signals sampled within 50 ns of laser excitation by time resolved electron spin echo (ese) spectroscopy in normal protonated, deuterated, deuterated ¹⁵N photosynthetic algae and broken chloroplasts. Previously, it has been shown that application of time resolved ese to study these systems, in particular, gives rise to two kinds of signals (standard and special ese). The standard ese signal at g = 2.0023 and the special ese signal exhibit similar electron spin echo envelope modulation (eseem). The modulation frequency and pattern can be identified with that obtained from stable oxidized P₇₀₀ in the same system. The two lower field resonances of the standard ese signal do not show eseem. The results support the proposed mechanism for formation of special ese and the notion that the standard ese is due to at least two radicals. It is also demonstrated that we can observe eseem of P⁺₇₀₀ under ambient temperature conditions.     

Evidence for Non-Innocence of a β-Diketonate Ligand

β-Diketonates, such as acetylacetonate, are amongst the most common bidentate ligands towards elements across the entire periodic table and are considered wholly redox-inactive in their complexes. Herein we show that complexation of 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac⁻) to Cr^II spontaneously affords Cr^III and a reduced β-diketonate radical ligand scaffold, as evidenced by crystallographic analysis, magnetic measurements, optical spectroscopy, reactivity studies, and DFT calculations. The possibility of harnessing β-diketonates as electron reservoirs opens up possibilities for new metal–ligand concerted reactivity in the ubiquitous β-diketonate coordination chemistry.     

Total Syntheses of 11-Acetoxy-4-deoxyasbestinin D, 4-Deoxyasbestinin C,Asbestinin-10, -20, -21 and -23

Six members of the asbestinin family of marine diterpene natural products have been synthesized in an efficient and stereoselective manner from a single oxa-bridged intermediate. Five of these natural products have not been synthesized previously and the structures of four of them have been confirmed as those proposed originally or following revisions to the original structures. The fifth natural product—asbestinin-21—has been shown to be a diastereomer of the compound that had been proposed previously.     

On the Origin of the “Giant” Electroclinic Effect in a “De Vries”‐Type Ferroelectric Liquid Crystal Material for Chirality Sensing Applications

W415 is a chiral smectic compound with a remarkably weak temperature dependence of its giant electroclinic effect in the liquid crystalline smectic A* phase. Furthermore it possesses a high spontaneous polarization in the smectic C* phase. The origin of this striking electroclinic effect is the co‐occurrence of a de Vries‐type ordering with a weak first‐order tilting transition (see the synchroton X‐ray scattering profiles).