Von den unabhängigen Reaktionen

Zusammenfassung Es wird der Begriff derunabhängigen Reaktionen dargelegt, die chemische und mathematische Methode der Ermittlung dieser Reaktionen dargetan und auf ihre Bedeutung verwiesen.     

Zur Literaturdokumentation in der Analytischen Chemie

Zusammenfassung Anhand von 298 Referaten aus Fresenius Z. Anal. Chem. werden systematisch geordnete Listen von Indexbegriffen für die Bereiche Methoden und Anwendungen erstellt und auf diese Referate angewendet. Diese vorläufige Systematik umfaßt 63 und 32 Hauptindexwörter. Den dokumentierten Referaten wurden 815 Schlüsselwörter (Hauptindexwörter) zugeordnet (116 Referate mit 2, 134 Referate mit 3 Hauptindexwörtern, Minimum: 1, Maximum: 5). Für zwei Indexabschnitte, Atomabsorptionsspektrometrie und Geologisches Material, wird die vorgeschlagene Indexierung vorgestellt und mit der bisherigen in Fresenius Z. Anal. Chem. verglichen. Die überschaubare Zahl von 95 Hauptindexwörtern, die erkennbare, einfache Systematik und die Wahlmöglichkeiten von zusätzlichen Nebenindexwörtern sollen zu einer benutzerfreundlichen Dokumentation beitragen, welche hiermit zur Diskussion gestellt wird.

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Literature documentation in analytical chemistryIV. Development of a systematic, easily usable index and documentation system

Summary By means of 298 abstracts from Fresenius Z. Anal. Chem. systematically arranged lists of index terms for the fields methods and applications were compiled and used for these abstracts. This preliminary system contains 63 and 32 first index terms. 815 Key words were allocated to the abstracts (= first index terms): 116 abstracts with 2, 134 abstracts with 3 first index terms, minimum: 1, maximum: 5. For two index sections, l.e. atomic absorption spectrometry and geological materials, the proposed indexing system is presented and compared with the system hitherto used in Fresenius Z. Anal. Chem.. The favourable number of 95 first index words, the obviously simple system and the possibility of selecting additional second index terms should contribute to an easily usable documentation, which is herewith presented for discussion.

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Teil III: Fresenius Z Anal Chem (1982) 312:448–454     

Synthese höherkondensierter Ringsysteme durch intermolekulare Dehydrierung verschiedener Moleküle unter Verknüpfung und Ringschluß.

Zusammenfassung Es wird gezeigt, daß demClarschen Terrylen eine andere Struktur zukommen dürfte und sein Dibromterrylen ein KW, vermutlich das Quaterrylen ist.Mit 3 Abbildungen.     

Philosophical aspects of chemometrical strategy in Analytical Chemistry

Summary This paper discusses the philosophical aspects of the three main chemometrical strategies in analytical chemistry: statistical data treatment, optimization and modelling, pattern recognition. It is possible by a more general consideration of these approaches to find a proper place of different philosophical categories such as form and content, induction and deduction, concrete and general in analytical chemistry. The philosophical aspect of the considerations allows a deeper penetration into the theoretical basis of chemical analysis.

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Philosophische Betrachtungen zu chemometrischen Strategien in der Analytischen Chemie

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Presented at the First International Symposium on History and Philosophy in Analytical Chemistry, Vienna, November 22–23, 1985     

Der o-Effekt in den Massenspektren aromatischer Verbindungen

Zusammenfassung Das Massenspektrum des O-Äthylsalicylsäureamides VII b ist von dem seiner m- und p-isomeren Verbindung völlig verschieden und zeigt einen typischen massenspektrometrischen o-Effekt.Die bisher aufgefundenen Verbindungen mit massenspektro-metrischem o-Effekt gehören einem relativ kleinen Kreis von Aromaten mit ganz bestimmten Strukturmerkmalen an. Die Bildung der für den o-Effekt charakteristischen Bruchstücke kann in allen diesen Fällen nach einem vonMcLafferty aufgestellten Mechanismus zwanglos erklärt werden. Verbindung VIIb hätte unter der Voraussetzung, daß eine Entstehung der für den o-Effekt typischen Fragmente nur nach diesem Mechanismus möglich ist, keinen o-Effekt zeigen dürfen.Das Auftreten des o-Effektes im Massenspektrum von VIIb läßt erkennen, daß die Bedingung zur Bildung der für den o-Effekt charakteristischen Bruchstücke lediglich in der Möglichkeit zur Ausbildung stabiler Spaltprodukte zu suchen ist, und daß daher weit mehr Verbindungen einen o-Effekt zeigen sollten als bisher anzunehmen war.Mit 1 Abbildung     

Multivariate Statistical Assessment of Air Quality: A Case Study

The present paper deals with the application of several chemometrical methods (cluster and principal components analysis, source apportioning on absolute principal components scores) to an aerosol data collection from Unterloibach, Austria. It is shown that seven latent factors explaining almost 80% of the total variance are responsible for the data structure and are conditionally identified as secondary aerosol, mineral dust, oil burning, lead smelter, coal burning, salt and fertilizer emission sources. Furthermore, the contribution of each identified source to the formation of the particle total mass and chemical compounds total concentration is calculated. Thus, a reliable assessment of the air quality in the region is performed. The requirements of the sustainability concept for ecological indicators in this case is easily transformed into a multivariate statistical problem taking into account not separate indicators but the specific multivariate nature of aerosol pollution.     

Determination of total,and bound Se in sera by INAA

In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via^77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.     

Similarity and dissimilarity in posets

The relevance of partially ordered sets (or posets) in a wide diversity of contexts in chemistry is emphasized, and the utility of distance functions (or metrics) on such posets is noted. First a notion of scale similarity is introduced to make comparisons within certain so-called scaled posets, for which there is formulated natural comparators, which in turn lead to associated distance functions. Beyond taking note of several chemically relevant examples of these scaled posets and their consequent associated similarity measures, a second chemically relevant class of so-called shifted posets is similarly developed, with examples. Even further extension of some aspects of the current approach is indicated, and finally the multi-posetic character of chemical periodic law is suggested.     

Meeting the need for reference measurements

Summary Reference materials do fulfil a very useful function in that they provide means to check, verify and calibrate measurement procedures and instrumentation. However, the material is often idealized compared to real life samples: it is either (very) pure or does not correspond in concentration level or matrix to the real life case. It is shown how this situation could be remedied if real life samples with carefully assessed reference values could be made available regularly as unknowns to measurement laboratories. Comparison of the latter's measurements with the reference values then would provide a picture of the real performance of the particular measurement community in general and of each participating laboratory in particular. The opinion is expressed that isotope-specific methods have now matured to the stage that, if they are correctly applied under rigorous control and based on highly skilled expertise, they can provide such reference values against which laboratories can then evaluate their routine performance in regular Interlaboratory Measurement Evaluation Programmes (IMEPs).

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Wie der Notwendigkeit von Referenzmessungen entsprochen werden kann

     

Natural flavours of wine: correlation between instrumental analysis and sensory perception

Summary The aroma of wine consists of 600 to 800 aroma compounds from which especially those, typical for the variety, are already present in the grapes. The aroma extracts — received by extraction with trichlorofluoromethane — are separated by gas chromatography. There are significant varietal differences between the aromagrams (fingerprint pattern). Thus the amount of some flavour compounds (key substances) shows typical dependence on the variety. Especially monoterpene compounds play an important role in the differentiation of wine varieties.The German white wines can be differentiated into three groups only by quantitative determination of 12 monoterpenes (terpene profile). These groups are: Riesling type, Muscat type and Silvaner-Weißburgunder type. Such terpene profiles are also useful for the separation of real Riesling wines from others called Riesling (e.g. Welschriesling, Kap Riesling, Emerald Riesling) but not produced from grapes of the variety Riesling. Including further components and by means of statistical methods as for example linear discriminant analysis even the different varieties within the mentioned groups (for instance the Riesling-group: Riesling, Kerner, Ehrenfelser, Bacchus, Müller-Thurgau) can be separated from each other.To identify compounds causing off-flavours the sniffing technique is the method of choice. The off-flavour is pinpointed during gas chromatography separation of the complex aroma mixture by effluent sniffing. Once allocated, the chemical nature of the off-flavours is elucidated by spectroscopic methods. Substances contributing to the green pepper taint, the strawberry note, mousiness, corkiness etc. in wine could be found in this way.     

On the recognition of structural features: Some general problems illustrated by hamiltonian paths in polyhexes

Human and machine recognition skills are discussed, though not comprehensively reviewed, and some of the difficulties are illustrated by algorithms written to search for Hamiltonian paths in polyhexes. The most successful strategy for this is based upon the branching graph, a recently introduced graph-theoretical device which can aid the recognition of edges that arenot part of a Hamiltonian path. Another, more widely applicable approach that is interesting, although in this preliminary form only a little better than random methods, uses the metaphor of biological evolution, and tries to breed and grow paths subjected to natural selection.     

Understanding the properties of isospectral points and pairs in graphs: The concept of orthogonal relation

The mathematical property orthogonal relationship is used in proving the fact that isospectrality, isocodality and isocoefficiency of vertices within a graph are all equivalent. The same is true for isospectrality, strict isocodality and strict isocoefficiency of pairs (including edges) within a graph, whereas the weak versions of the latter properties are necessary but not sufficient for isospectrality of pairs. Similarly, necessary and sufficient conditions for isospectrality of vertices and pairs in different graphs are derived. In all these proofs, the concept of orthogonal relation plays a major role in that it allows the use of tools of elementary linear algebra.     

Interplay of Thermochemistry and Structural Chemistry,the Journal (Volume 13, 2002) and the Discipline

As practiced disciplines, structural chemistry and thermochemistry need not be related. In the current study they are: the contents of the journal Structural Chemistry (Vol. 13) for the year 2002 have been reviewed and then most articles that appeared therein were given a thermochemical commentary, spin or slant.     

Determination of polychlorobiphenyls and polycyclic aromatic hydrocarbons in the atmospheric aerosol of the Venice Lagoon

An analytical method for simultaneous determination of particle-associated and gaseous-phase concentrations of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) in atmospheric aerosol samples obtained by high-volume samplers using polyurethane foam adsorbent (PUF) and quartz fibber filters (QFF) has been investigated. Quality control of the analytical procedure was carried out by blank control and by evaluating limits of detection, recoveries, accuracy, and repeatability. The proposed method was subsequently used to determine PAH and PCB in the gaseous and particulate phases of the aerosols that enter the Venice Lagoon atmosphere. The highest concentrations of PCB and PAH were predominantly in the gaseous phase. In both particulate and gaseous phases the penta-CB congeners dominated total PCB concentrations whereas phenanthrene, fluoranthene, and pyrene dominated the PAH concentrations. Total (gaseous plus particulate) PCB and PAH concentrations were higher at the site directly influenced by the industrial plants but the concentrations in marine aerosol samples were lower by a factor four only and must be taken into consideration when studying the chemical contamination of the Venice Lagoon.     

QSAR of copper(II) complexes with cytotoxic properties

Summary A QSAR based on a multiple regression analysis for 15 copper(II) semi- and thiosemicarbazone complexes with cytotoxic properties is presented. In vitro cytotoxicity was selected as the dependent variable and Van der Waals volumes (Vm), octanol- water partition coefficients (logP), specific rate constants of the copper(II) complexes towards superoxide radicals (k _s ) and variation in C=N vibration bands (CN) in IR spectra of the complexes with respect to the free ligands were selected as the independent variables. The stepwise regression procedure and the all possible regressions were practiced in the analysis of the data. The orthogonality analysis proved noncollinearity among the variables. According to the obtained equation the two best copper(II) complexes were submitted to a broad in vivo screening study and resulted to be active against La, P-388 and L-1210 leukemias.

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QSAR von Kupfer(II)-Komplexen mit cytotoxischen Eigenschaften

Zusammenfassung Es wird eine quantitative Struktur-Aktivitäts-Beziehung basierend auf einer multiplen Regressionsanalyse für 18 Kupfer(II)-Semi- und Thiosemicarbazon-Komplexe präsentiert. Die in vitro-Cytotoxizität wurde als die abhängige Variable und Van-der-Waals-Volumina (Vm), Octanol-Wasser-Verteilungskoeffizienten (logP), spezifische Geschwindigkeitskonstanten der Kupfer(II)-Komplexe gegenüber Superoxid-Radikalen (k _s ) und die Variationen der C=N-Vibrationsbanden (CN) in den IR-Spektren der Komplexe gegenüber den freien Liganden als unabhängige Variablen eingeführt. Es wurde stufenweise Regression und die alle möglichen Regressionen-Prozedur in der Analyse der Daten verwendet. Die Orthogonalitätsanalyse zeigte Nichtkolinearität der Variablen an. Entsprechend den erhaltenen Gleichungen wurden die beiden besten Kupfer(II)-Komplexe einem breiten in vivo-Screening unterworfen. Sie waren gegenüber La, P-388 und L-1210 Leukemie aktiv.

     

Theoretical am1 studies of inclusion complexes of α- and β-cyclodextrins with methylated benzoic acids and phenol,and γ-cyclodextrin with buckminsterfullerene

Semiempirical AM1 calculations have been performed on the inclusion complexes of - and -cyclodextrin with benzoic acid and phenol and -cyclodextrin with methylated benzoic acids in the head first and tail first positions. The results show that -cyclodextrin complexes with phenol and benzoic acid guests in the head first position are more stable than in the tail first position, while -cyclodextrin complexes with the same guests prefer the tail first position. The preferred orientation for -cyclodextrin with methylated benzoic acids is determined by the position of the methyl substituent(s). In general, para-methyl benzoic acid derivatives prefer the tail first position. -cyclodextrin forms a slightly unstable 1:1 complex with C₆₀ (3.4 kcal/mol), but two -cyclodextrins provide enough stabilization by about 10 kcal/mol to cage-in the C₆₀.     

Identification of the plant source of the Chinese crude drug „Dan-zhu-ye“ using the low-temperature plasma ashing technique

Summary A microchemical approach for the identification of plant source of Chinese diuretic crude drug Dan-zhu-ye using low-temperature plasma ashing is reported. The specimen was ashed on a microscope slide and the remaining ashed tissue was microscopically compared with other specimens of bamboo and bamboo grasses. Characteristic distribution patterns of silicon bodies and their shape in Dan-zhu-ye have suggested that the plant source of the crude drug isLophatherum sinense Rendle or at least its very close relative.

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Zusammenfassung Über die Ergebnisse der Tieftemperatur-Veraschung der chinesischen Rohdroge Dan-zhu-ye zwecks pflanzlicher Zuordnung dieses Diureticums wurde berichtet. Das Untersuchungsobjekt wurde auf einem Objektträger verascht und der Geweberückstand unter dem Mikroskop mit anderen Proben von Bambus und Bambusgräsern verglichen. Charakteristische Verteilungsmuster von Siliziumkörperchen und deren Form in Dan-zhu-ye legen die Annahme nahe, daß die Droge von Lophatherum sinense Rendle stammt oder ihm wenigstens sehr nahe steht.

     

Small-angle X-ray scattering studies of the open and closed conformations of aspartate aminotransferase

Summary Aspartate aminotransferase was investigated by X-ray small-angle scattering. A small difference was found between the open (active) and the closed (liganded) conformation of the enzyme. The results were compared with X-ray crystallography data.

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Untersuchungen zur Röntgenkleinwinkelstreuung der offenen und geschlossenen Konformation von Aspartat-Aminotransferase

Zusammenfassung Aspartat-Aminotransferase wurde mittels Röntgenkleinwinkelstreuung untersucht. Ein kleiner Unterschied zwischen der offenen (aktiven) und der geschlossenen (ligandierten) Konformation wurde gefunden. Die Ergebnisse wurden mit Röntgenkristallstrukturdaten verglichen.

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Abbreviations AspAT aspartate aminotransferase     

A Note on Distance Matrices Yielding Elementary Landscapes for the TSP

Symmetric and antisymmetric distance matrices in the single agent traveling salesman problem (TSP) are not the only distance matrices to generate elementary landscapes for swap and 2-opt neighborhoods.     

Reaktionskinetische Kuriosa

Zusammenfassung Die in der chemischen Kinetik seltenen und seltsamen, aber grundsätzlich möglichen und zu einem Gleichgewicht führenden Erscheinungen werden als Kuriosa bezeichnet. Hierher gehören die Zirkularreaktionen, der periodische Reaktionsablauf und dasWegscheidersche Paradoxon. Sie werden charakterisiert und es werden die Bedingungen aufgezeigt, unter welchen sie rechnungsmäßig in Erscheinung treten.