Rapid determination of microorganisms using a flow-injection system

An automated method for the rapid determination of microorganisms using a flow-injection system is presented. Electrochemical measurement of a mediator reduced by microbial metabolism allowed the determination of fungi and bacteria in a few minutes. The lowest detection limit was 5 × 10⁶ colony-forming units (cfu) ml^?1 for Escherichia coli. Correlation between the flow-injection method and standard microbiological methods was excellent (r = 0.997, n = 4 for Beauveria bassiana; r = 0.997, n = 7 for E. coli). The flow-injection system was applied to the on-line control of an E. coli cultivation.     

Conformational Analysis of 1,2:3,4-Diepoxides: Ab Initio and semiempirical molecular-orbital calculations

Using semiempirical and ab initio procedures, the most stable conformations of meso- and rac-bioxirane and of some substituted 1,2:3,4-diepoxides were calculated. For threo-diepoxides (having the same relative configurations as rac-bioxirane, 3 ), two stable conformations with CCCC dihedral angles of ca. 90 and ca. 270° were found. For erythro-diepoxides (derivatives of meso-bioxirane, 4 ) the calculations suggest three preferred conformations with corresponding dihedral CCCC angles of ca. 90°, ca. 180°, and ca. 270°. The calculations are in fair agreement with the experimental data available for the unsubstituted compounds 3 and 4 .     

A liquid chromatographic system with multi-detection for the direct analysis of hydrophilic organic compounds in natural waters

Summary A combined analytical LC/HPLC system was developed which allows the direct and continuous determination of organic carbon (OC), inorganic carbon (IC), UV-Vis, fluorescence, and organically bound nitrogen in aqueous solutions in the low g/l concentration range. The arrangement is well suited as detector for the direct chromatographic characterisation of organic constituents in natural surface- and groundwaters without any sample pretreatment.     

Analysis of proteins from a glioma cell line by using micro-scale solution isoelectric focusing in combination with liquid chromatography/tandem mass spectrometry

In this study we have investigated whether micro-solution isoelectric focusing (microsol-IEF) can be used as a pre-fractionation step prior to liquid chromatography/tandem mass spectrometry (LC/MS/MS) and if extensive sample purification of the different fractions is required. We found that, in spite of the high concentrations of buffer and detergents, no clean up of the digested microsol-IEF fractions was necessary before analysis by LC/MS/MS. We also concluded that it is possible to identify at least twice as many proteins in a glioma cell lysate with the combination of microsol-IEF and LC/MS/MS than with LC/MS/MS alone. Furthermore, most of the proteins that were identified from one microsol-IEF fraction by using analytical narrow-range two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and peptide mass fingerprinting with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) were also identified by LC/MS/MS. Finally, we used the combination of microsol-IEF and LC/MS/MS to compare two sample preparation methods for glioma cells and found that several nuclear, mitochondria, and endoplasmic reticulum proteins were only present in the sample that had been subjected to lipid extraction by incubating the homogenized cells in chloroform/methanol/water.     

Aurophilicity-coordination interplay in the design of cyano-bridged nickel(II)-Gold(I) bimetallic assemblies: structural and computational studies of the gold(I)-gold(I) interactions

Two polymorphic cyano-bridged Au(I)-Ni(II) bimetallic complexes of formulas [Ni(en)2Au(CN)2][Au(CN)2] (1) and [Ni(en)2[Au(CN)2]2] (2) have been prepared from the 1:2 reaction between [Au(CN)2]- and either [Ni(en)2Cl2]Cl or [Ni(en)3]Cl2.2H2O, respectively. The structure of 1 consists of polymeric cationic chains of alternating [Au(CN)2]- and [Ni(en)2]2+ units running along the a axis and [Au(CN)2]- anions lying between the chains. The noncoordinated dicyanoaurate anions are aligned perpendicular to the ac plane and involved in aurophilic interactions with the bridging dicyanoaurate groups, ultimately leading to a 2D bimetallic grid. The structure of 2 consists of trinuclear molecules made of two [Au(CN)2]- anions linked to [Ni(en)2]2+ unit in trans configuration. Trinuclear units are joined by aurophilic interactions to form 1D zigzag chains. The magnetic properties of these compounds are strongly dominated by the local anisotropy of the octahedral Ni(II) ions, thus indicating that the magnetic exchange interaction mediated by dicyanoaurate bridging groups, if it exists, is very weak. To get insight into the electronic properties of the inter- and intramolecular interactions of the [Au(CN)2]- building blocks, the structures of different aggregates of dicyanogold units were optimized and then analyzed by making use of atoms-in-molecules (AIM) theory. Moreover, bond indices were calculated by methods based upon nonlinear population analysis.     

PHOTOCHEMISTRY OF FLAVINS—I. CONVENTIONAL AND LASER FLASH PHOTOLYSIS STUDY OF ALLOXAZINE

Abstract— The photobleaching of alloxazine in buffered aqueous solution has been studied by means of flash photolysis using conventional and laser excitation sources. Several transient species have been characterized. The alloxazine triplet state (Λ_max 420 nm and 550 nm, times; = 9 μs) was identified with the aid of low-temperature comparison experiments in ethanol. Transient absorption with Λ_max 440 nm, which appears after decay of the triplet state, and whose second-order decay is pH-dependent, is postulated to be due to the semiquinone radical (AH₂*) and a radical derived from alloxazine by addition of water and loss of a hydrogen atom (HAOH*), which are in equilibrium with their conjugate cation radicals. The results of experiments in the presence of oxygen indicate that these species are not primarily formed from the triplet state. The enhanced second-order decay of the flavin radicals in oxygen-containing solutions is interpreted in terms of their reaction with the peroxy radicals. The proposed mechanisms account for the production of hydroxylated alloxazines.     

Die Bestimmung von Derivaten der Kohlensäure über eine saure Verseifung

Zusammenfassung Durch Hydrolyse in siedender, hochkonzentrierter Phosphorsäure läßt sich anscheinend aus allen Kohlensäurederivaten quantitativ Kohlendioxid abspalten. Dieses wird nach Reinigung und Trocknung gravimetrisch bestimmt. Folgende Verbindungen wurden analysiert: lineare und cyklische Harnstoffe, Thioharnstoffe, Urethane, Carbamate, Kohlensäureester, Phenylisocyanat, Melamin, Guanidin, Cyanursäure und Dicyandiamid. Die Anwendung verschiedener Phosphorsäurekonzentrationen erlaubt auch selektive Bestimmungen.

---

The determination of derivatives of carbonic acid via an acidic hydrolysis

Summary Hydrolysis in boiling highly concentrated phosphoric acid seemingly results in the quantitative splitting off of carbon dioxide from all derivatives of carbonic acid. The latter is determined gravimetrically after purification and drying. The following compounds were analyzed: linear and cyclic ureas, thioureas, urethanes, carbamates, esters of carbonic acid, phenylisocyanate, melamine, guanidine, cyanuric acid, dicyandiamide. The use of various concentrations of phosphoric acid permits selective determinations.

---

---

Herrn Prof. Dr.B. Timm zum 60. Geburtstag gewidmet.     

Zur Kenntnis der anomalen Reaktionen bei der Aminostickstoffbestimmung. VI Die Anomalie des Indols und seiner Derivate

Zusammenfassung Es wurde untersucht, warum Indol und viele seiner Derivate bei der Aminostickstoffbestimmung ein Gasvolumen liefern, obwohl sie keine primäre Aminogruppe besitzen. An Hand von präparativen Befunden wird gezeigt, daß die anomale Reaktion bei Indol in folgender Weise abläuft: Bei Einwirkung von salpetriger Säure bildet sich 3-Nitrosoindol, das sieh mit freiem Indol zu Indolrot polymerisiert. Gleichzeitig lagert sich die Nitrosogruppe zur Isonitrosogruppe um. Diese reagiert nun mit überschüssiger salpetriger Säure unter Entwicklung von Stickstoff und Distickstoffoxyd. Ist die Stellung 2 und 3 besetzt, so bleibt die anomale Gasentwicklung aus, da sich keine Isonitrosoverbindung bilden kann. Es wurde auch das Verhalten von 3-Methylindol und 3-Indolylessigsäure untersucht und die anomale Reaktion erörtert.

---

Summary A study was made to learn why indole and many of its derivatives deliver a gas volume during the determination of the amino nitrogen, even though they contain no primary amino group. On the basis of preparative findings, it was shown that in the case of indole the anomalous reaction proceeds in the following fashion. When the nitrous acid reacts, 3-nitrosoindole is formed, which then polymerizes with free indole to indole red. At the same time, the nitroso group rearranges into the isonitroso group. The latter reacts with excess nitrous acid with evolution of nitric oxide and nitrogen dioxide. If positions 2 and 3 are occupied, there is no anomalous generation of gas, because no isonitroso compound can form. The behavior of 3-methylindole and 3-indylacetic acid was also studied and the anomalous reaction noted.

---

Résumé Les auteurs ont recherché pourquoi l'indol et nombre de ses dérivés donnent lieu à un dégagement gazeux lors de la détermination de l'azote aminé bien qu'ils ne contiennent aucun groupement aminé primaire. Des constatations effectuées au cours de travaux de chimie préparative ont montré que la réaction anormale de l'indol a le cours suivant: lors de l'action de l'acide nitreux il se forme du nitroso-3 indol qui en présence d'indol libre se polymerise en rouge d'indol. Simultanément le groupement nitrosé se transpose en groupement isonitrosé. Ce dernier réagit alors avec l'acide nitreux en excès en donnant lieu à un dégagement d'azote et de protoxyde d'azote. Si les positions 2 et 3 sont occupées il ne se produit pas de dégagement gazeux anormal car la combinaison isonitrosée ne peut se former. Les auteurs ont également examiné le comportement du méthyl-3 indol et de l'acide indoyl-3 acétique et discuté leurs réactions anormales.

---

---

I: Anomalie der Isonitrosoverbindungen¹; II: Anomalie der Verbindungen mit NH-CO-Gruppierung²; III: Anomalie der Verbindungen mit aktiven Methylengruppen³; IV: Anomalie von Glycin⁴; V: Anomalie der Phenole⁵.