bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscopy of biological sample through advanced diffractive optics from visible to x‐ray wavelength regime
Authors: Di Fabrizio Enzo , Cojoc Dan , Emiliani Valentina , Cabrini Stefano , Coppey‐Moisan Maite , Ferrari Enrico , Garbin Valeria , Altissimo Matteo
Published: January 2005

The aim of this report is to demonstrate a unified version of microscopy through the use of advanced diffractive optics. The unified scheme derives from the technical possibility of realizing front wave engineering in a wide range of electromagnetic spectrum. The unified treatment is realized through the design and nanofabrication of phase diffractive elements (PDE) through which wave front beam shaping is obtained. In particular, we will show applications, by using biological samples, ranging from micromanipulation using optical tweezers to X‐ray differential interference contrast (DIC) microscopy combined with X‐ray fluorescence. We report some details on the design and physical implementation of diffractive elements that besides focusing also perform other optical functions: beam splitting, beam intensity, and phase redistribution or mode conversion. Laser beam splitting is used for multiple trapping and independent manipulation of micro‐beads surrounding a cell as an array of tweezers and for arraying and sorting microscopic size biological samples. Another application is the Gauss to Laguerre‐Gauss mode conversion, which allows for trapping and transfering orbital angular momentum of light to micro‐particles immersed in a fluid. These experiments are performed in an inverted optical microscope coupled with an infrared laser beam and a spatial light modulator for diffractive optics implementation. High‐resolution optics, fabricated by means of e‐beam lithography, are demonstrated to control the intensity and the phase of the sheared beams in x‐ray DIC microscopy. DIC experiments with phase objects reveal a dramatic increase in image contrast compared to bright‐field x‐ray microscopy. Besides the topographic information, fluorescence allows detection of certain chemical elements (Cl, P, Sc, K) in the same setup, by changing the photon energy of the x‐ray beam. Microsc. Res. Tech. 65:252–262, 2004. © 2005 Wiley‐Liss, Inc.
Monitoring of glass derivatization with pulsed force mode atomic force microscopy
Authors: Ebner Andreas , Kienberger Ferry , Stroh Cordula M. , Gruber Hermann J. , Hinterdorfer Peter
Published: January 2005

Non‐specific adsorption of proteins at solid/liquid interfaces is a major problem in the use of synthetic biomaterials and in ultrasensitive detection methods. Grafting surfaces with a dense layer of poly(ethylene glycol) (PEG) or other polymers is a most widely used strategy to solve this task. While such modified surfaces have been characterized by their ability to resist protein adsorption, the polymer layers themselves have rarely been studied in fine detail. Atomic force microscopy (AFM) using the pulsed force mode (PFM), is an ideal technique to investigate structural features and physiochemical properties of surfaces because topology and adhesion are simultaneously detected with high lateral resolution. In the present study, PFM‐AFM was applied to thoroughly characterize different stages of glass derivatization, up to the formation of a dense PEG layer. Lateral inhomogeneities in topology and/or adhesion were observed at all stages before PEG attachment. The covalently bound PEG, however, was seen to form a densely packed monolayer with maximal thickness, smooth surface, and weak adhesion. Thus, PFM‐AFM appears to be a valuable tool for the characterization of protein‐repelling surfaces in solution. Microsc. Res. Tech. 65:246–251, 2004. © 2005 Wiley‐Liss, Inc.
Single molecule spectroscopic characterization of GFP‐mut2 mutant for two‐photon microscopy applications
Authors: Cannone Fabio , Caccia Michele , Bologna Sara , Diaspro Alberto , Chirico Giuseppe
Published: January 2005

Green Fluorescent Protein (GFP) mutants are extensively used in optical microscopy studies of in vivo biological processes in cells. Nonetheless, blinking and bleaching of the GFP chromophore at the single molecule level greatly limits its usefulness. We have worked out what we think are the best experimental conditions for the use of the GFP mutant, GFP‐mut2, as a single molecule marker in two‐photon excitation measurements. We have measured molecular brightness, excited state lifetime, blinking and photo‐bleaching times versus the two‐photon excitation intensity on proteins embedded in silica gel matrices versus the excitation wavelength in the range 700–1,000 nm. Our results indicate that GFPmut2 can be employed as a long‐lived reporter of biological processes. Microsc. Res. Tech. 65:186–193, 2004. © 2005 Wiley‐Liss, Inc.
Chemical and thermal denaturation of crystalline bacterial S‐layer proteins: An atomic force microscopy study
Authors: Toca‐Herrera José L. , Moreno‐Flores Susana , Friedmann Jacqueline , Pum Dietmar , Sleytr Uwe B.
Published: January 2005

Crystalline monomolecular cell surface layers, S‐layers, are one of the most common outermost cell envelope components of the prokaryotic organisms (bacteria and archaeda) that protects them from competitive habitats. Since isolated S‐protein subunits are able to re‐assemble into crystalline arrays on lipid films and solid supports making biomimetic surfaces, S‐layer technology is currently used in nanobiotechnology. An important aspect of the biomimetic surfaces built with S‐layers is their stability under extreme solvent conditions or temperature. Chemical (pH, alcohol) and physical (thermal) denaturant conditions were employed to test the stability of S‐layers. Recrystallized bacterial surface layers from Bacillus sphaericus (SbpA) on hydrophilic silicon wafers loses the crystalline structure at 80% ethanol/water mixtures, the change in structure being reversible after treating the surface with buffer solution. SbpA on silicon supports denatures at pH 3 and at 70°C, and the process is irreversible. Cross‐linking of SbpA enhances the stability for high ethanol and acidic conditions, but it does not improve thermal stability. Recrystallized SbpA on secondary cell wall polymer (SCWP), a natural environment for the protein layer, is more resistant to ethanol and pH exposure than recrystallized SbpA on hydrophilic silicon supports. Atomic force microscopy (AFM) was used to monitor the loss of stability and the changes in protein layer conformation. Microsc. Res. Tech. 65:226–234, 2004. © 2005 Wiley‐Liss, Inc.
Ensemble and single particle photophysical properties (two‐photon excitation, anisotropy, FRET, lifetime, spectral conversion) of commercial quantum dots in solution and in live cells
Authors: Grecco H.E. , Lidke K.A. , Heintzmann R. , Lidke D.S. , Spagnuolo C. , Martinez O.E. , Jares‐Erijman E.A. , Jovin T.M.
Published: January 2005

In this work, we characterized streptavidin‐conjugated quantum dots (QDs) manufactured by Quantum Dot Corporation. We present data on: (1) two‐photon excitation; (2) fluorescence lifetimes; (3) ensemble and single QD emission anisotropy; (4) QDs as donors for Förster resonance energy transfer (FRET); and (5) spectral conversion of QDs exposed to high‐intensity illumination. We also demonstrate the utility of QDs for (1) imaging the binding and uptake of biotinylated transferrin on living cells, and (2) resolving by fluorescence lifetime imaging microscopy (FLIM) signals originating from QDs from those of spatially and spectrally overlapping visible fluorescent proteins (VFPs). Microsc. Res. Tech. 65:169–179, 2004. © 2005 Wiley‐Liss, Inc.
Rice proteome analysis: A step toward functional analysis of the rice genome
Authors: Komatsu Setsuko , Tanaka Naoki
Published: January 2005

The technique of proteome analysis using 2‐DE has the power to monitor global changes that occur in the protein complement of tissues and subcellular compartments. In this review, we describe construction of the rice proteome database, the cataloging of rice proteins, and the functional characterization of some of the proteins identified. Initially, proteins extracted from various tissues and organelles were separated by 2‐DE and an image analyzer was used to construct a display or reference map of the proteins. The rice proteome database currently contains 23 reference maps based on 2‐DE of proteins from different rice tissues and subcellular compartments. These reference maps comprise 13 129 rice proteins, and the amino acid sequences of 5092 of these proteins are entered in the database. Major proteins involved in growth or stress responses have been identified by using a proteomics approach and some of these proteins have unique functions. Furthermore, initial work has also begun on analyzing the phosphoproteome and protein‐protein interactions in rice. The information obtained from the rice proteome database will aid in the molecular cloning of rice genes and in predicting the function of unknown proteins.
Feasibility Exploration of Laser‐based Techniques for Characterization of a Flashing Jet
Authors: Yildiz Dilek , van Beeck Jeronimus P. A. J. , Riethmuller Michel L.
Published: January 2005

Two‐phase flows hold an interest in many areas of science and engineering. In the safety field, one such topic is the accidental release of flammable and toxic pressure‐liquefied gases. In case of such a release, a flashing vapor explosion takes place resulting in a very dense two‐phase cloud. If the released substance is flammable, this cloud can be combustible and can lead to deflagration or detonation. For understanding the source processes of flashing and risk assessment, data related to cloud characteristics (i.e. droplet size, velocity etc.) is needed especially in the near region of the release. Due to the non‐equilibrium nature of the near field regions accurate data measurement is not possible with intrusive techniques. Therefore, laser‐based optical techniques (like Particle Image Velocimetry (PIV), Particle Tracking Velocimetry and Sizing (PTVS), Phase Doppler Anemometry (PDA) etc.) present the only possibility to obtain information for particle diameter and velocity evolution in this harsh environment.
Fractal Character of Dynamic Light Scattering of Particles
Authors: Shen Jin , Zheng Gang , Sun Guoqiang , Tu Qijun
Published: January 2005

Dynamic light scattering signals from particles, exhibit fractal characteristics. This feature can be used to determine the particle size. The use of the fractal dimension, as a quantitative method to analyze the properties of dynamic light scattering signals from submicron particles, is presented. The analysis is performed directly on the time‐resolved scattered intensity, and the Box Dimensions of light scattering signals of particles with diameters 100, 200, 500 and 1000 nm. The experimental results show that the fractal dimensions of light scattering signals correlate well with particle size. In the submicron size range, the smaller the particles, the larger their fractal dimensions. Compared with the PCS technique, only several hundreds of samples are required in the fractal method. Therefore, the data processing is easily accomplished. However, this method only provides the mean particle size, but not the particle size distribution.
Size Measurement of Very Small Spherical Particles by Mie Scattering Imaging (MSI)
Authors: Graßmann Arne , Peters Franz
Published: January 2005

The Mie Scattering Imaging method (MSI) gathers out‐of‐focus images of dispersed spherical particles present in a laser light sheet and extracts the individual particle diameter from these images. The general idea of the method has been around for more than a decade and a number of papers has dealt with it over recent years. Our work focuses on small particle sizes from 20 μm down to 2 μm, a range which has not been tackled so far although it is of great importance in particle systems. We present an optical set‐up with a special arrangement of camera lenses that allows to work in this range. An evaluation algorithm based on correlation of the experimental optical information with theoretical Mie scattering was found to give the most accurate results for particle sizing. Besides accuracy measurements on solid spheres the versatility of the method is demonstrated by an example of transient droplet growth between 2–7 μm.
Analysis of Particle Size Distribution by Particle Tracking
Authors: Finder Christiane , Wohlgemuth Michael , Mayer Christian
Published: January 2005

Particle tracking is performed using a combination of dark field or fluorescence video microscopy with automatic image analysis. The optical detection together with the image analysis software allows for the time resolved localization of individual particles with diameters between 100 and 1000 nm. Observation of their Brownian motion over a set of time intervals leads to the determination of their mean square displacements under the given room temperature and viscosity. Hereby, the radii of a set of particles visible within a given optical frame are derived simultaneously. Rapid data analysis leads to reliable particle size histograms. The applicability of this method is demonstrated on polystyrene latices and PMMA nanospheres with radii between 51 nm and 202 nm.
An Electroacoustic Investigation of Concentrated Aqueous Suspensions of Calcium Pyrophosphate
Authors: Greenwood Richard
Published: January 2005

The zeta potential of concentrated suspensions of calcium pyrophosphate were investigated using electroacoustics. The particles were negatively charged over the entire pH range studied. It proved impossible to reduce the pH of the suspension below 1.8, but the iso electric point could be estimated to occur at approximately pH 1. Two commercially available dispersants (one cationic and one anionic) were then added in small increments to the suspension in order to follow the change in zeta potential as the dispersants adsorbed onto the particles. From the shape of the curve it was possible to estimate the optimum adsorbed amount of dispersant required to fully coat the particles. The cationic dispersant adsorbed strongly and the optimum dosage was estimated at 2.5 ml of active polymer/kg of powder. Anionic dispersants are known to adsorb onto negatively charged ceramic oxide particles, but the anionic dispersant used in this study did not adsorb onto the negatively charged calcium pyrophosphate particles.
On‐line Determination of Particle Size Distributions in Flowing Dispersions
Authors: Belhabri Monia , Legrand Jack , Le Sauze Nathalie , Arhaliass Abdellah
Published: January 2005

Emulsions are of great importance to industry. They are involved in many engineering operations, including chemical reactions, extraction, emulsification and suspension polymerization, etc. However, an important problem for these processes is how to control the size distribution of the dispersed phase. Indeed, off‐line analysis of the emulsion may generate uncertainties due to sampling and dilution of the product, which are likely to change the dispersion state and physico‐chemical properties. In this work, an on‐line optical method is proposed to characterize dispersed media in real flowing conditions. This method is based on the time‐analysis of back‐scattered light fluctuations. The present paper deals with the development of this method and its application to dispersions of alumina in water. The results obtained with the on‐line optical method are compared with those acquired by classical laser light scattering and microscopy.
Zur Kenntnis der Druckinkohlung von Braunkohlen in Gegenwart von Wasser. III
Authors: Leibnitz E. , Köunnecke H.‐G. , Lietz L.
Published: January 2005

Um einen vertieften Einblick in die Primärvorgänge der Inkohlungsreaktionen von Braunkohlen in Gegenwart von Wasser zu bekommen, wurden die erhaltenen Sekundärkohlen verschwelt. Die Ergebnisse lassen den Schluß zu, daß bei Inkohlungsreaktionen die Decarboxylierung und Dehydratisierung ab etwa 300° C zugunsten einer Spaltung der Huminsäuren zurückgedrängt wird.
Die Nebenbestandteile einer auf Braunkohlenbasis gewonnenen m‐p‐Kresolfraktion
Authors: Dietzsch Klaus
Published: January 2005

Die m‐p‐Kresolfraktion enthält neben Kresolen noch insgesamt 17% Guajacol, o‐Äthylphenol, 2,4‐Dimethylphenol, 2,5‐Dimethylphenol und 2,6‐Dimethylphenol. In Arbeiten von LANDA und MOSTECKÝ wird aus den Veröffentlichungen von PREISS der Schluß gezogen, daß in dem aus mitteldeutscher Braunkohle hergestellten Braunkohlenschwelteer o‐Äthylphenol nicht festgestellt wurde. Demgegenüber wird nachgewiesen, daß das o‐Äthylphenol in der m‐p‐Kresolfraktion mit zu suchen ist und in dieser einen wesentlichen Nebenbestandteil darstellt.
Über einige Glykoside des m‐Äthylphenols
Authors: Helferich Burckhardt , Rullmann Karl Heinz
Published: January 2005

Es wird die Synthese des β‐D‐Glucosids und des β‐D‐Galaktosids vom m‐Äthylphenol und einiger Derivate dieser Glykoside beschrieben.
Zur Kenntnis der Trithiokohlensäure. IV. Über die Herstellung und Eigenschaften von Trithiokohlensäure‐di‐estern und ihre Verwendbarkeit als Schädlingsbekämpfungsmittel
Authors: Runge Franz , El‐Hewehi Zaki , Renner Hans‐Joachim , Taeger Eberhard
Published: January 2005

Trithiokohlensäure‐di‐ester der aliphatischen, araliphatischen und aromatischen Reihen wurden hergestellt und ihre chemischen sowie biologischen Eigenschaften untersucht.

Das leicht zugängliche Barium‐trithiocarbonat hat sich bei der Herstellung von aliphatischen und araliphatischen Estern bewährt.

Von den untersuchten Estern zeigten lediglich die Diaryl‐trithio‐carbonate günstige insektizide Wirkung.
Katalytische Untersuchungen an Legierungen XX1. Zur Wirkungsweise der Verstärkung metallischer Hydrierungskatalysatoren
Authors: Kinza Horst , Rienäcker Günther
Published: January 2005

Nach einem Überblick über die wichtigsten Vorstellungen über aktive Zentren werden eigene Versuche über die Hydrierung von Zimtsäureäthylester an pulverförmigen Nickel‐Eisen‐Legierungen und entsprechenden SiO2‐Trägerkatalysatoren beschrieben, die zur Klärung des Einflusses von Trägersubstanzen auf die aktiven Zentren beitragen sollen.

Abschließend werden Möglichkeiten zur Erklärung der Wirkung von Legierungsbestandteilen diskutiert.
Darstellung höherer primärer n‐Alkylamine und Di‐(n‐alkyl)‐hydrazine durch katalytische Hydrierung von Polyenaloximen und ‐azinen
Authors: Losse Günter , Müller Jutta
Published: January 2005

Die Polyenaloxime und ‐azine liefern bei der katalytischen Druckhydrierung an Raney‐Nickel‐Kontakten in guter Ausbeute die entsprechenden Mono‐n‐alkylamine. Durch Reduktion der Polyenalazine mit Lithiumaluminiumphybrid gewinnt man zunächst Di‐(n‐polyenyl)‐hydrazine, deren vorsichtige Weiterhydrierung zu den Di‐(n‐alkyl)‐hydrazinen führt.
Benzazole. XVII. MANNICH‐Basen des d,l‐trans‐Hexahydrobenzoxazolthions
Authors: Zinner Helmut , Schritt Wolfgang
Published: January 2005

Die MANNICH‐Reaktion von d,l‐trans‐Hexahydrobenzoxazolthion mit Formaldehyd und sekundären aliphatischen sowie primären aromatischen Aminen wird untersucht.
Zur katalytischen Hydrierung aromatisch‐substituierter Imidazole. V. [Diphenylyl‐(4)]‐imidazole
Authors: Schubert Hermann , Jaenecke Günter , Taubert Hans
Published: January 2005

Es wird die Synthese aller C‐substituierten [Diphenylyl‐(4)]‐imidazole beschrieben. Diese Basen geben bei der katalytischen Hydrierung die entsprechenden [Dicyclohexylyl‐(4)]‐imidazole in Form von Stereoisomerengemischen, aus denen nur in wenigen Fällen sterisch einheitliche Formen zu isolieren waren. Die als Stereoisomerengemische wie auch als einheitliche trans‐Formen synthetisierten [Dicyclohexylyl‐(4)]‐imidazole sind mit den Hydrierungsprodukten identisch. Der Diphenylylrest „lockert”︁ das Imidazolsystem nicht für eine katalytische Hydrierung.
Über die Reaktivität des 1.2.3.4‐Tetrahydro‐chinaldins
Authors: Buchmann Gerhard , Pracht Heinz
Published: January 2005

Chinaldin wurde zum 1.2.3.4‐Tetrahydrochinaldin hydriert und N‐Alkylderivate dargestellt.

Das 1.2.3.4‐Tetrahydroderivat konnte durch Oxydation nicht zum Aminoxyd umgesetzt werden; es zeigte sich, daß das tetrahydrierte Ringsystem teilweise zum Chinaldin dehydriert und zum Chinaldin‐N‐oxyd oxydiert wurde.

Bei der Nitrierung wurden N‐Alkyl‐7‐nitro‐verbindungen erhalten, die sich zu N‐Alkyl‐6‐brom‐7‐nitro‐tetrahydro‐chinaldinen bromieren ließen. Die umgekehrte Reaktionsfolge führte zu den gleichen Brom‐nitroderivaten.

Die N‐Alkylverbindungen wurden mit elementarem Brom zu den N‐Alkyl‐6‐bromtetrahydro‐chinaldinen bromiert.

Bei der Reduktion der Nitroderivate wurden die entsprechenden primären Amine erhalten und als Schiffsche Basen charakterisiert.

IR‐spektroskopische Untersuchungen bestätigten, daß sich die N‐Alkylderivate des Tetrahydrochinaldins bei elektrophilen Reaktionen wie N.N‐Dialkylaniline verhalten.
N,N′‐Bis‐(β‐hydroxyäthyl)‐terephthalsäurediamid, N,N′‐Terephthaloyl‐bis‐(ω‐aminocarbonsäuren) und N,N′‐Terephthaloyl‐bis‐(aminoarylcarbonsäuren)
Authors: Zinner Helmut , Sych Georg , Ludwig Werner
Published: January 2005

N,N′‐Bis‐(β‐hydroxyäthyl)‐terephthalsäurediamid, N,N′‐Terephthaloyl‐bis‐(ω‐aminocarbonsäuren) und N,N′‐Terephthaloyl‐bis‐(aminoarylcarbonsäuren) werden dargestellt, letztere in ihre Methylester übergeführt. Die Stabilität der Verbindungen bei höheren Temperaturen wird untersucht.
Polyesteramide der Terephthalsäure
Authors: Zinner Helmut , Sych Georg , Ludwig Werner
Published: January 2005

Aus N,N′‐Terephthaloyl‐bis‐(Ω‐aminocarbonsäuremethylestern) und Äthylenglykol werden Polyesteramide, aus Terephthalsäuredimethylester, N,N′‐Terephthaloyl‐bis (Ω‐aminocarbonsäuremethylestern) und Äthylenglykol Mischpolyesteramide dargestellt.
Synthese spasmolytisch wirksamer Substanzen. XVI. Synthese von α‐Phenyl‐α‐(N′,N′‐dialkylaminoalkyl)‐amino‐essigsäure‐amiden
Authors: Klosa Josef
Published: January 2005

Arylaldehyde setzen sich mit den mineralsauren Salzen von N′,N′‐Dialkylamino‐alkylaminen und Alkylicyaniden zu α‐Aryl‐α‐(N′,N′‐Dialkylaminoalkyl)‐amino‐essig‐säure‐nitrilen um, von denen eine Anzahl mit konz. Schwefelsäure zu α‐Aryl‐α‐(N′,N′‐dialkyl‐aminoalkyl)‐amino‐essigsäure‐amiden verseift werden konnten.
Formation of Complex Compounds between uranyl nitrate and the nitrates of the first group elements. The systems:(a) uranyl nitrate—lithium nitrate—water (b) uranyl nitrate—sodium nitrate—water (c) uranyl nitrate—potassium nitrate—water (d) uranyl nitrate—ammonium nitrate—water (conductivity, pH and spectrophotometry)
Authors: Gupta S. S. , Pande C. S.
Published: January 2005

Experiments with the systems: Uranyl nitrate — Lithium nitrate — Water, Uranyl nitrate — Sodium nitrate — Water, Uranyl nitrate — Potassium nitrate — Water, Uranyl nitrate — Ammonium nitrate — Water, viz., conductivity, pH and spectrophotometry revealed that in the first system there is no compound formation, in the second system only one complex compound is formed in the (1 : 1) molecular artio whereas in the last two systems two complexes are observed individually in the (1 : 1) and (1 : 2) molecular ratios respectively.
Über Zwangskonstellationen bei cyclischen 1.2‐Aminoalkoholen
Authors: Drefahl G. , Heublein G. , Din Pak Thä
Published: January 2005

An Hand von IR‐Spektren werden die Konstellationsverhältnisse bei einigen 1‐alkyl‐substituierten 1,2‐Aminoalkoholen untersucht.
Synthesen mit N,N′‐disubstituierten Schwefelsäurediamiden. III. Über die Alkylierung 1,3‐disubstituierter Schwefelsäurediamide
Authors: Sowada Rudolf
Published: January 2005

1,3‐Disubstituierte Schwefelsäurediamide lassen sich in 30proz. Natronlauge mittels Dialkylsulfaten bzw. Arylsulfonsäurealkylestern in Ausbeuten bis zu 92% der Theorie alkylieren. Die Eigenschaften der neuen Verbindungen werden angegeben.
Synthesen mit Methallylchlorid (=1‐Chlor‐2‐methylpropen‐(2))
Authors: Profft E. , Oberender H.
Published: January 2005

Es wird über Synthesen mit 1‐Chlor‐2‐methylpropen‐(2) berichtet, speziell über tertiäre N‐Methallylamine, Halogenierungsprodukte hiervon, Reaktionen dieser und über Ketobasen der N‐[(2‐Methyl‐3‐cyano)‐propyl]‐amine vom Falicain‐Typus. Diese wirken wesentlich stärker als Cocain. Eine neue Reihe von Diaminen wird beschrieben.
Die Oxydation von isopropylbenzol zu Cumolhydroperoxid mit Ozon als Initiator
Authors: Wagner Günter
Published: January 2005

Ozon als Gasinitiator der Kohlenwasserstoffoxydation vermag eine Doppelrolle zu spielen. Kurzzeitig in der Anfangsphase der Oxydation zugesetzt, bewirkt es in höherer Konzentration einen beschleunigten Zerfall der primär gebildeten Hydroperoxide, während der Einsatz geringerer Ozonkonzentrationen bei der Gasinitiierung zu einer beträchtlichen Stimulierung der Hydroperoxidbildung, im Vergleich zum nichtinitiierten Prozeß, führt. Durch Zugabe von 0,01–1,0 Vol.‐% in der Anfangsphase der Cumoloxydation mit Sauerstoff oder Luft in praktisch homogener Phase bei 95–120°C und Sodazusatz, kann die Bildung von Cumolhydroperoxid wesentlich beschleunigt werden.
Derivate des Phosphorsäure‐o‐phenylenesters. VII. Heptachlor‐benzo‐1,3,2‐dioxaphosph(V)ol
Authors: Gloede Jörg , Gross Hans
Published: January 2005

Die RAMIREZ‐Reaktion konnte auf die Umsetzung von Phosphor(III)‐halogeniden ausgedehnt werden: aus Tetrachlor‐o‐chinon und Phosphortrichlorid ist Heptachlor‐benzo‐1,3,2‐dioxaphosph(V)ol 2 zugänglich. Solvolysereaktionen von 2 führen unter Ringöffnung zu Phosphorsäuretetrachlorhydroxyphenylestern 4ac bzw. 10a, während Äthylenoxid unter Erhalt des Dioxaphosph(V)olringes den Orthophosphorsäureester 3 gibt. Aus 2 und Acetanhydrid entsteht über mehrere Zwischenstufen das pentacovalente Spiroderivat 12, das auch aus Tetrachlor‐o‐chinon und Phosphorigsäureäthylesterdichlorid dargestellt werden konnte.
Über die elektrochemische und katalytische Reduktion von N‐Nitroso‐1‐methylamino‐1‐desoxy‐zuckeralkoholen und deren O‐Acetyl‐Derivaten
Authors: Dorn Helmut , Arndt Dieter , Wand Horst
Published: January 2005

N‐Nitroso‐1‐methylamino‐1‐desoxy‐D‐ribit, ‐D‐ und ‐L‐arabinit sowie ‐D‐xylit 1d–g werden in 1n HCl an einer großflächigen Quecksilberkathode zu entsprechenden N‐Methyl‐N‐(tetrahydroxy‐pentyl)‐hydrazinen 2d–g reduziert. Ein elegantes Verfahren zur Darstellung kristalliner N‐Nitroso‐1‐methylamino‐1‐desoxy‐penta(tetra)‐0‐acetylhexite(pentite) mit D‐Glucit‐, D‐Mannit‐, D‐Galaktit‐, D‐Ribit‐, D‐ und L‐Arabinit‐ sowie D‐Xylit‐Konfiguration (6h–o) wird beschrieben. Die katalytische Hydrierung von 6k mit RANEY‐Nickel liefert unter basenkatalysierter O → N Acylwanderung N‐Acetyl‐1‐methylamino‐1‐desoxy‐D‐galaktit 8c. Salze penta‐O‐acetylierter 1‐Methylamino‐1‐desoxy‐zuckeralkohole mit freier N—H‐Funktion 9h, 9k werden durch Hydrieren entsprechender N‐Benzyloxycarbonyl‐1‐methylamino‐1‐desoxy‐penta‐O‐acetyl‐hexite 12h, 12k in Gegenwart von 1 Mol Säure gewonnen.

1‐Methylamino‐1‐desoxy‐zuckeralkohole 10a–g, durch Hydrieren von Aldosen und Methylamin leicht zugänglich, werden in wäßrigem Milieu mit hohen Ausbeuten N‐carbobenzoxyliert und N‐tosyliert. N‐Tosyl‐1‐methylamino‐1‐desoxy‐penta‐O‐acetyl‐hexite 14h–k erhält man in hohen Ausbeuten direkt aus 10a–c; sie sind identisch mit den Tosylierungsprodukten von 9h bzw. 9k. An zahlreichen Beispielen N‐substituierter 1‐Methylamino‐1‐desoxy‐zuckeralkohole wird gezeigt, daß die WEYGANDschen Drehungsregeln zur Festlegung der Konfiguration am C—2 nur bedingt brauchbar sind.
Spektroskopische Untersuchungen der Wechselwirkung zwischen Äthylaminen und Tetrachlormethan
Authors: Bittrich H. J. , Schütze K.
Published: January 2005

Die Gleichgewichtskonstanten und Bildungsenthalpien der Donator‐Akzeptor‐Wechselwirkung von Triäthylamin und Tetrachlormethan wurden UV‐spektroskopisch bestimmt. Daraus und aus Literaturwerten für Diäthylamin‐Tetrachlormethan wurden die spezifischen Anteile der Exzeßfunktionen berechnet und mit Mischungsmodellen verglichen. Die Übereinstimmung ist für den Anteil in HE relativ gut, während das Modell für GE nur Vorzeichen und Größenordnung richtig wiedergibt.
Solanum‐Alkaloide. XCIV. Partialsynthese von Solacongestidin aus Solasodin
Authors: Adam G. , Voigt D. , Schreiber K.
Published: January 2005

Es wird eine Reaktionsfolge zur partialsynthetischen Umwandlung des Steroidalkaloids Solasodin in Solacongestidin beschrieben.
Preparation of Some MANNICH Bases from 2‐amino‐ and 2‐allylamino‐4‐methyl‐5‐acetyl‐thiazole
Authors: Suciu D.
Published: January 2005

From 2‐amino‐(1 a) and 2‐allylamino‐4‐methyl‐5‐acetyl thiazole (2 a) and the N‐acylated compounds 1 b–f the correspondent MANNICH bases of the type RCOCH2CH2NR2 · HCl(NR2 = morpholino, piperidino, dimethylamino, diethylamino and diisopropylamino) were prepared and characterized as phenylhydrazones. The bromination of these MANNICH compounds gave α‐bromo‐β‐aminoketones.
Dehydrierung 1‐substituierter Pyrazolidone‐(3) in Gegenwart von Formaldehyd und sekundären Aminen
Authors: Dorn Helmut , Otto Albrecht , Dilcher Herbert
Published: January 2005

Die Dehydrierung der N‐MANNICH‐Derivate 2 1‐substituierter Pyrazolidone‐(3) ergibt C‐MANNICH‐Derivate 5 1‐substituierter 3‐Hydroxy‐pyrazole. Die Ausbeute an 5 ist quantitativ, wenn der 1‐Substituent Aryl ist und nimmt mit zunehmender Zahl der α‐H‐Atome im 1‐Substituenten ab. Als Nebenprodukte entstehen 1‐Alkyliden‐ bzw. 1‐Aralkyliden‐pyrazolidon‐(3)‐N1⊕,N2⊖‐betaine (Azomethinimine) 6. 5 erhält man auch direkt aus 1‐substituierten Pyrazolidonen‐(3), Formaldehyd, sekundären Aminen und Jod. NMR‐, IR‐Spektren und Reaktionsmechanismen werden diskutiert. 1‐Cyclohexylpyrazolidon‐(3) 1 b wird von Jod zu 3‐Hydroxy‐1‐cyclohexylpyrazol 3c und dem Azomethinimin 6c dehydriert, mit Brom entsteht außerdem 4‐Brom‐3‐hydroxy‐pyrazol 4c.
Über die Cyclisierung von 1,5‐Diacyl‐2‐alkyl‐diamino‐guanidinen und 1‐Acyl‐2‐alkyl‐5‐carbamoyl‐diaminoguanidinen zu 1,2,4‐Triazolen
Authors: Gehlen H. , Segeletz H.
Published: January 2005

1,5‐Diacyl‐2‐alkyl‐diaminoguanidine 1 cyclisieren unter Wasserabspaltung zu 3‐(Nα‐Alkyl‐Nβ‐acylhydrazino)‐5‐aryl‐1,2,4‐triazolen 3. Die Cyclisierung der 1‐Acyl‐2‐alkyl‐5‐carbamoyldiaminoguanidine 2 führt zu 2‐Alkyl‐3‐[semicarbazido‐(1)]‐5‐aryl‐1,2,4‐triazolen 5. Aus 3 und 5 lassen sich durch Säurehydrolyse die entsprechenden Hydrazinotriazole 4 und 6 darstellen.
MO‐LCAO‐Berechnungen an Polymethinen. IV. Zum DÄHNEschen Konzept der gekoppelten Polymethine
Authors: Fabian J. , Tröger‐Naake G.
Published: January 2005

Ausgehend von einer quantenchemischen Charakterisierung des Polymethinzustandes, die in den vorangegangenen Arbeiten behandelt wurde, wird die Bedeutung der Streptopolymethin‐Teilsysteme für komplizierte molekulare Strukturen untersucht. Um die Elektronenstruktur des zusammengesetzten Systems mit denen der partizipierenden Teilsysteme zu vergleichen, werden die elektronischen Wellenfunktionen der Konfigurationsanalyse unterworfen. Die Lokalisierbarkeit in atomare und molekulare Subsysteme wird durch Indizes bewertet. Danach können zahlreiche Strukturen aus polymethinischen, polyenischen und aromatischen Fragmenten zusammengesetzt gedacht werden. Bei einigen carbo‐ und heterocyclischen π‐Systemen ist das Baukastensystem nur begrenzt anwendbar. Die Anwendungsbreite des Modells kann aber durch Anwendung der einfachen Störungstheorie 2. Ordnung leicht erkannt werden.
Darstellung und Eigenschaften von Pyrazolo[3,2‐c]benzo‐1,2,4‐triazinen und Pyrazolo[3,2‐c]pyrido[4,3‐e][1,2,4]triazinen
Authors: Hauptmann S. , Blattmann G. , Schindler W.
Published: January 2005

α,β‐Ungesättigte β‐Aminonitrile 1 kondensieren mit 2‐Nitrophenylhydra‐zin und mit 4‐Hydrazino‐3‐nitropyridin zu Hydrazonen von β‐Ketosäurenitrilen 2 bzw. 3. Diese Verbindungen cyclisieren bei der Einwirkung von Basen zu Pyrazolo[3,2‐c]benzo‐1,2,4‐triazin‐5‐oxiden 7 bzw. Pyrazolo[3,2‐c]pyrido[4,3‐e] [1,2,4]triazin‐5‐oxiden 8. Die N‐Oxide lassen sich mittels Natriumdithionit zu den entsprechenden Triazinen 9, 10 reduzieren.
Zur Auswertung von UV‐Vis‐Spektren schwacher organischer π‐π‐Molekülkomplexe. X Die Beeinflussung der spektroskopischen und thermo‐dynamischen Charakteristika der Komplexbildung bei sterischer Hinderung
Authors: Bendig J. , Kreysig D. , Templer G.
Published: January 2005

Für die TCNQ‐Komplexe des Anthracens sowie dessen 9‐Methyl‐, 9,10‐Dimethyl‐, 9‐Phenyl‐ und 9,10‐Diphenylderivate wurden die Assoziationskonstanten, Komplex‐bildungsenthalpien und ‐entropien bestimmt. Es zeigt sich eine Abnahme der Komplexbildungs‐fähigkeit bei zunehmender Phenylsubstitution, hervorgerufen durch eine sterische Hinderung der Komplexbildung. Letzteres führt zu größeren Werten für die Reaktionsentropie und infolge größerer Gleichgewichtsabstände zu kleineren Bildungsenthalpien im Vergleich zum Anthracen/TCNQ‐Komplex. Die erhaltenen Ergebnisse für die Molekülkomplexe im Grundzustand stehen in Einklang mit der Fähigkeit der Donatoren zur Photodimerisierung.
Mononuclear Benzoylhydrazide Complexes of Cu2+, Fe3+ and V5+O and Fe2+ sulphate. Single crystal X‐ray and E.P.R. data of the Cu2+ complex
Authors: Iskander George M. , Salama Salama B. , Osman Abdel Rahaman H. , Gulta Eman L. , Schlemper Elmer O.
Published: January 2005

Benzoyl hydrazide monoligand complexes [M(BzH)]n+, where M = Cu2+, Fe2+, Fe3+ and V5+O are prepared and their physical data reported. X‐ray single crystal diffraction of Cu(BzH)CI2 reveal a nearly square planar configuration around the Cu2+; the benzoyl hydrazide molecule acting as a bidentate ligand with the CO and NH2 groups as coordinate sites and the partial contribution of the chloride ions as well. E.p.r. showed a low spin orbital coupling (500 cm−1) versus 830 cm−1 for the free Cu2+ ion; obviously coordinate bond chelation for the Cu2+ ion is envisaged.
(1S,2S)‐2‐Amino‐1‐aryl‐propane‐1,3‐diols as convenient educts for the Synthesis of Homochiral (S,S)‐Norpseudoephedrine
Authors: Boerner Armin , Krause Hanswalter
Published: January 2005

A convenient high yield synthesis of homochiral norpseudoephedrine starting from waste products of the chloramphenicol synthesis is described as an example of its utilization in chemical transformations.
Studies on the reaction of o‐benzoquinone dioxime with aldehydes: An improved procedure for 1‐Hydroxybenzimidazole 3‐Oxides
Authors: Pätzold F. , Niclas H.‐J. , Gründemann E.
Published: January 2005

An improved method for the preparation of the title compounds 4 is described. Thus, 1‐hydroxybenzimidazole 3‐oxides are obtained in high yields by the reaction of o‐benzoquinone dioxime 1 with aromatic and heteroaromatic substituted aldehydes 2 in the presence of an excess of strong acids. The primarily formed salts 3 are transformed into 4 by neutralization. The reaction is assumed to proceed via the nitroso‐nitrone 6 as intermediate.
Synthese von Benzylidenaminopyrazolen und Bispyrazolopyridinen
Authors: Hennig L. , Hofmann J. , Alva‐Astudillo M. , Mann G.
Published: January 2005

Synthesis of Benzylideneaminopyrazoles and Bispyrazolopyridines

5‐Aminopyrazoles 1a–e react with aromatic aldehydes in boiling ethanol to yield azomethines 2a–n. Bispyrazolopyridines 7a–f are obtained by the reaction of 2a–f with an excess of aminopyrazole at higher temperatures via bisaminopyrazoles 5 and bispyrazolodihydropyridines 6. Structure and configuration of the products are assigned by n.m.r.‐spectroscopy. Reactions with replacement of the arylidene group on azomethine 2b suggest that the transformation of azomethines to bisaminopyrazoles occurs through a mechanism involving addition of the CH‐acidic component, with subsequent elimination of aminopyrazole.
Synthese, koordinationschemische und massenspektrometrische Charakterisierung neuartiger carboxylsubstituierter N‐(Thiocarbamoyl)‐benzamidine
Authors: Hartung J. , Weber G. , Beyer L. , Kirmse K. , Stach J.
Published: January 2005

Synthesis, Coordination Chemistry and Mass Spectrometric Fragmentation of New N‐(Thiocarbamoyl)‐benzamidines

Syntheses of N‐(thiocarbamoyl)benzamidines from benzimidoylchlorides and aromatic amino acids as starting materials are reported. The prepared compounds were used as ligands for complexing nickel(II) and copper(II)ions. The benzamidines were characterized by mass spectrometric methods. The fragmentation pattern of the benzamidines was derived from the corresponding MIKE‐spectra.
Kinetische Untersuchungen zur Radikalisch induzierten Fragmentierung von Orthoformiaten des 2,2,3,3,4,4,5,5‐Octafluorpentan‐1‐ols
Authors: Gizatullina S. R. , Jakupov I. S. , Germač A. V. , Zlotskij S. S. , Rachmankulov D. L. , Timpe H.‐J.
Published: January 2005

Kinetical Investigations on Radical Initiated Fragmentation of Orthoformiates of 2,2,3,3,4,4,5,5‐Octafluoropentan‐1‐ol

tert.‐Butoxy radicals abstract the methin hydrogen atom on orthoesters 1 of 2,3,3,4,4,5,5‐octafluoropentan‐1‐ol, and the radicals 2 thus formed fragmente at 130°C into dialkylcarbonates 3. Due to their acceptor properties the fluoroalkyl substituents influence the velocity of the hydrogen abstraction reaction. On the contrary, no influence of these substituents on the rate of the fragmentation step has been measured. With 2‐fluoroalkyl substituted 1,3‐dioxolanes the radical induced fragmentation leads to ring‐opened carbonates, which are the major products, and ethylene carbonate.
Zur Elektrochemie von 2‐Trichlormethyl‐tetrahydrofuranen
Authors: Fechtel U. , Westphal K. , Matschiner H.
Published: January 2005

Electrochemistry of 2‐Trichloromethyl‐tetrahydrofurans

4‐Alkoxy‐2‐trichloromethyl‐4‐methyl‐tetrahydrofurans (2) were prepared by anodic oxidation of 1,1,1‐trichloro‐4‐methyl‐pent‐4‐en‐2‐ol (1) in presence of bromide ions and bases. Electroreductions of these compounds in LiCl/Methanol lead to 2‐dichloromethyl‐tetrahydrofurans (6). Under acidic conditions an olefin (10) was formed as main product.
Kinetische Untersuchungen zur Reaktion von Methylradikalen mit But‐2‐in
Authors: Claus P. , Marquardt M. , Trung Tran Kim , Scherzer K.
Published: January 2005

Kinetic Investigation of the Reactions of Methyl Radicals with But‐2‐yne

The reactions of methyl radicals with but‐2‐yne have been studied in a greaseless static vessel in the temperature range 543 ⃛583 K. The methyl radicals were generated by thermolysis of azomethane (initial pressures 2.66 kPa and 3.19 kPa) in mixtures with the alkyne (initial pressures 0 ⃛7,8 kPa). The primary steps are H‐abstractions producing 3‐methylpropargyl radicals and additions to the triple bond forming trimethylvinyl radicals. Both radicals were stabilized by hydrogen abstraction from the parent compounds and by combination processes. The temperature dependence of the rate constant k2 for the addition reaction can be expressed by the equation k2 = 108.65±0.20exp (−40300 ± 1300)Jmol−1/RT M−1 s−1 For the rate constant k1 of hydrogen abstraction a value of k1 = 1,65 · 105M−1 s−1 at 573 K was estimated. Therefore the H‐abstraction proceeds about two times faster than the addition reaction.
2‐Dialkylamino‐thiazolin‐4‐one aus α‐Thiocyanato‐carbonsäurederivaten
Authors: Zimmermann T. , Fischer G. W. , Olk B.
Published: January 2005

2‐Dialkylamino‐thiazolin‐4‐ones from α‐Thiocyanato‐carboxylic Acid Derivatives

α‐Thiocyanato‐acetic acid esters 1a‐c or amide 1d react with dialkylamine salts of weak acids to give 2‐dialkylamino‐thiazolin‐4‐ones 2a‐f. The reaction can be performed using aliphatic alcohols, dipolar aprotic solvents or halogenated hydrocarbons as reaction medium or by heating the educts at 90°C without any solvent. According to the latter method, the 5‐substituted thiazolinones 2g, h are obtained from α‐thiocyanatopropionic acid ethyl ester (1d) or α‐thiocyanato‐phenylacetic acid ethyl ester (1e) and dimethylamine acetate. ‐ I.r., u.v. and n.m.r. data of the thiazolinones 2 are reported.
Push‐pull‐Butadiene. XI. Darstellung und Reaktionen von Methylsulfonylnicotinonitrilen
Authors: Peseke K. , Schönhusen U.
Published: January 2005

Push‐pull‐Butadienes. XI. Syntheses and Reactions of Methylsulfonylnicotinonitriles

Methylthionicotinonitriles 1, 3, 5, 9 and 12 react with potassium permanganate to give corresponding methylsulfonylnicotinonitriles 2, 4, 6, 10 and 13, respectively. Compounds 2 can be converted with sodium ethoxide to yield diethoxynicotinonitriles 7. Similarly 4, 5 and 6 react with sodium ethoxide to give 4‐aryl‐5‐bromo‐2,6‐diethoxy‐nicotinonitriles 8. Treatment of nicotinonitriles 9, 10 or 13 with sodium ethoxide gives diethoxynicotinonitriles 11. 2 with hydrazine hydrate together afford pyrazolo[3,4‐b]pyridines 14. However, an excess of hydrazine hydrate and 2 or 6 yields hydrazinopyrazolo[3,4‐b]pyridines 15.
Substituierte N,N′‐Bis(thiazol‐2‐yl)‐diaminoalkane aus α‐Thiocyanato‐acetophenonen und N,N′‐Dialkyl‐diamino‐alkanen
Authors: Zimmermann T. , Fischer G. W. , Teller J. , Dehne H. , Olk B.
Published: January 2005

Substituted N,N′‐Bis(thiazol‐2‐yl)‐diaminoalkanes from α‐Thiocyanato‐acetophenones and N,N′‐Dialkyl‐diaminoalkanes

α‐Thiocyanato‐acetophenones 1 react with N,N′‐dialkyl‐diaminoalkanes 2 in the presence of an appropriate weak acid (acetic acid, propionic acid, benzoic acid) to give the hitherto unknown N,N′‐dialkyl‐N,N′‐bis(4‐aryl‐thiazol‐2‐yl)‐diaminoalkanes 3. As reaction medium aliphatic alcohols (ethanol, methanol), halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) or dipolar‐aprotic solvents (acetonitrile, dimethylformamide) can be used. ‐ I.r., u.v., n.m.r. and mass spectroscopic data of the novel bisthiazoles 3 are reported.
Zerfall von 1‐n‐Butylaminocyclohexyl‐phosphonsäure‐di‐n‐butylester (Buminafos) in wäßrigem Medium
Authors: Schneider B. , Porzel A. , Weidhase R. , Schütte H. R.
Published: January 2005

Degradation of n‐Butylaminocyclohexyl phosphonic Acid di‐n‐Butylester (Buminafos) in Aqueous Medium.

In aqueous medium, breakdown of Buminafos (1) is connected with total loss of its herbicidal activity. The phosphorus‐carbon bond is cleaved and n‐butylcyclohexylidene amine (3), cyclohexanone (5), phosphoric acid mono‐n‐butyl ester (4) (partly as n‐butylamine salt), and 1‐aminocyclohexyl phosphonic acid di‐n‐butylester (8) were found as degradation products of carbon‐14 labeled Buminafos. Identification was performed by MS, GC/MS, 1H‐ and 31P‐n.m.r. spectroscopy, by detection of phosphorus, and by means of the radioactivity.
Synthese und Dimroth‐Umlagerung von disubstituierten 5‐Imino‐1,2,4‐dithiazolidin‐3‐thionen (Senfölsulfiden)
Authors: Tittelbach Franz
Published: January 2005

Synthesis and Dimroth Isomerization of Disubstituted 5‐Imino‐1,2,4‐dithiazolidine‐3‐thiones (Mustard Oil Sulfides).

Treatment of N‐substituted dithiocarbamates with N‐substituted S‐chloroisothiocarbamoyl chlorides leads to disubstituted 5‐imino‐1,2,4‐dithiazolidine‐3‐thiones. Educts with different aromatic substituents give the diaryl derivatives 5, as expected by the reaction equation. Educts with one aromatic and one aliphatic substituent give 5‐alkylimino‐4‐aryl derivatives 10, regardless which starting component (3, 4, 7, 8) possesses the aliphatic or aromatic substituent. Educts with different aliphatic substituents (7, 8) leads to mixtures of isomeric derivatives 12, 13. Disubstituted 5‐imino‐1,2,4‐dithiazolidine‐3‐thiones with 5‐alkylimino group are able for Dimroth isomerization to 4‐substituted 2‐alkyl‐1,2,4‐thiadiazolidine‐3,5‐dithiones.
Massenspektrometrisches Fragmentierungsverhalten ausgewählter Push‐Pull‐Alkene
Authors: Kleinpeter E. , Rasch K. , Rudorf W.‐D. , Schmidt J.
Published: January 2005

Mass Spectrometric Behaviour of the Fragmentation of Selected Push‐Pull Alkenes.
Synthese von 2‐Aminopimelinsäure‐1‐amid und Hexan‐6‐lactam‐6‐carboxamid
Authors: Bischoff Christian , Schröder Edith
Published: January 2005

Synthesis of 2‐Aminopimelic‐acid‐1‐amide and Hexane‐6‐lactam‐6‐carboxamide.
Thiocyclam durch Schweflung von Nereistoxin
Authors: Schubert H. , Heinicke J. , Mühlstädt M.
Published: January 2005

A Preparation of Thiocyclam by Sulfurization of Nereistoxin.
Developing a sound basis for the design of vented explosion barricades in chemical processes
Authors: Herrmann David D.
Published: January 2005

Most commonly used barricade design methods are based on taking an explosion scenario and treating it as a “TNT equivalent.” A widely used approach in the chemical industry is documented in TM5‐1300. Although this may be a reasonable approach for explosives in cubical barricades, it may not always relate well to the reality of many chemical facilities. This paper discusses some of the limitations of the TM5‐1300 method, the need for a good definition of the hazardous event(s), and the use of computational fluid dynamics to define blast loads for barricade design. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005
Automation vs. Human intervention: What is the best fit for the best performance?
Authors: Haight Joel M. , Kecojevic Vladislav
Published: January 2005

In today's complex industrial processes, automated control systems are a necessity. However, is complete automation the answer? Whereas control system automation provides predictable, consistent performance, it is lacking in human judgment, adaptability, and logic. Although humans provide these, we are unpredictable, inconsistent, and subject to emotions and motivation. To maximize system performance, should we automate humans out of the system? … or … Do we maximize human input and lose efficient, consistent, error‐free system performance? The answer is likely somewhere in the middle of these two extremes and different for each system and situation. This paper provides a review of the existing literature covering control schemes and parameters that determine system performance. It attempts to help answer the questions “How can we minimize human error while still maximizing system performance?” and “What is the right human–machine mix?” © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005
Poole–Frenkel effect in Er doped SnO2 thin films deposited by sol‐gel‐dip‐coating
Authors: Morais Evandro A. , Scalvi Luis V. A. , Ribeiro Sidney J. L. , Geraldo Viviany
Published: January 2005

Electrical properties of Er‐doped SnO2 thin films obtained by sol‐gel‐dip‐coating technique were measured. When compared to undoped tin dioxide, rare‐earth doped films present much higher resistivity, indicating that Er3+ presents an acceptor–like character into the matrix, which leads to a high degree of electric charge compensation. Current–voltage characteristics, measured above room temperature for Er‐doped films, lead to non‐linear behavior and two conduction regimes. In the lower electric field range the conduction is dominated by Schottky emission over the grain boundary potential barrier, which presents an average value of 0.85 eV. Increasing the applied bias, a second regime of conduction is observed, since the Poole–Frenkel coulombic barrier lowering becomes a significant effect. The obtained activation energy for ionization is 0.67 eV. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The double modulation superstructure of the room temperature stable phase of stoichiometric Cu2Te
Authors: Vouroutzis N. , Frangis N. , Manolikas C.
Published: January 2005

The structure of the room temperature phase αI‐Cu2Te is studied by means of electron diffraction and high resolution electron microscopy. It is found that the structure is the result of two modulations. The first one is the periodic introduction of planar translation interfaces perpendicular to the [111]c direction of the fcc basic structure. The second one is the ordering of Cu in octahedral and tetrahedral sites, in a way similar to that known for the β‐Cu2Se structure. The superstructure unit cell includes twelve Te layers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)