bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordinated control and experimentation of the dental arch generator of the tooth‐arrangement robot
Authors: Zhang Yong‐de , Jiang Jin‐gang , Lv Pei‐jun , Wang Yong
Published: September 2010

Background

The traditional way of acquiring the dental arch curve form is based on manual operation, which will randomly bring numerous errors caused by human factors. The purpose of this paper is to automatically acquire the dental arch curve and implement the coordinated control of the dental arch generator of the multi‐manipulator tooth‐arrangement robot, which can be used in full denture manufacturing.

Methods

Based on the arc length constant theory, kinematics on dental arch generator is analyzed. The control pulse realization methods of high‐resolution timing and CPU time‐stamp timing are studied, and testing and comparative analysis of the control precision and stability of the two methods is carried out. Control experimentation of the dental arch generator and preliminary tooth‐arrangement experimentation are performed using the multi‐manipulator tooth‐arrangement robot system.

Results

The dental arch generator can automatically generate a dental arch curve that fits a patient according to the patient's jaw arch parameters. Repeated positioning accuracy is 0.12 mm for the slipways which drive the dental arch generator. The maximum value of single point error is 1.64 mm when the arc width direction (x‐axis) is 37.25 mm. The experimental results indicate that the method of control pulse realized by high‐resolution timing to achieve high precision coordinated motion control of dental arch generator of tooth‐arrangement robot is feasible. The error analysis results indicate that the control strategy and technical route can fulfill the requirements for motion speed and location precision.

Conclusion

A novel system to generate the tooth arch curve has been developed. The traditional method of manually determining the dental arch may soon become obsolete in favour of the use of a robot to assist in generating a more standard tooth arch curve. The system can be used to manufacture a full denture. It will lay an important theoretical foundation for quantitative research of oral restoration, and also provide a way to standardize the manufacturing process of full denture. Copyright © 2010 John Wiley & Sons, Ltd.
Rapid Prototyping of Nanofluidic Systems Using Size‐Reduced Electrospun Nanofibers for Biomolecular Analysis
Authors: Park Seung‐min , Huh Yun Suk , Szeto Kylan , Joe Daniel J. , Kameoka Jun , Coates Geoffrey W. , Edel Joshua B. , Erickson David , Craighead Harold G.
Published: September 2010

Biomolecular transport in nanofluidic confinement offers various means to investigate the behavior of biomolecules in their native aqueous environments, and to develop tools for diverse single‐molecule manipulations. Recently, a number of simple nanofluidic fabrication techniques has been demonstrated that utilize electrospun nanofibers as a backbone structure. These techniques are limited by the arbitrary dimension of the resulting nanochannels due to the random nature of electrospinning. Here, a new method for fabricating nanofluidic systems from size‐reduced electrospun nanofibers is reported and demonstrated. As it is demonstrated, this method uses the scanned electrospinning technique for generation of oriented sacrificial nanofibers and exposes these nanofibers to harsh, but isotropic etching/heating environments to reduce their cross‐sectional dimension. The creation of various nanofluidic systems as small as 20 nm is demonstrated, and practical examples of single biomolecular handling, such as DNA elongation in nanochannels and fluorescence correlation spectroscopic analysis of biomolecules passing through nanochannels, are provided.
Synthesis of Superparamagnetic CaCO3 Mesocrystals for Multistage Delivery in Cancer Therapy
Authors: Zhao Yang , Lu Yang , Hu Yan , Li Jian‐Ping , Dong Liang , Lin Li‐Ning , Yu Shu‐Hong
Published: September 2010

To develop a new system for site‐specific targeting, superparamagnetic CaCO3 mesocrystals with the properties of biocompatibility and biodegradability are designed and synthesized. They serve as carriers for the co‐delivery of drug and gene nanoparticles via a multistage method for cancer therapy. With a porous structure, the mesocrystalline CaCO3 particles encapsulate doxorubicin (DOX), Au–DNA, and Fe3O4@silica nanoparticles for magnetic control and therapy. As stage 1 microparticles (S1MPs), the nanoparticles–CaCO3 system is designed to protect functional sections from degradation and phagocytosis in blood circulation. After the particle margination in vascular walls, the Au–DNA nanoparticles (stage 2 nanoparticles, S2NPs) and DOX are gradually released from S1MPs by degradation towards targeted tissues for biomedical therapy. The nanoparticles–CaCO3 system exhibits high efficiency of intracellular delivery, especially in nuclear invasion. The successful expression of reporter gene and intracellular transport of DOX in vitro suggest potential as a co‐delivery system for drug and gene therapy. In a mouse tumor model, the system with particle margination and two‐step strategy affords the protection of functional nanoparticles and drug from clearance and inactivation by enzymes and proteins in vivo. The targeted delivery of S2NPs into tumors by this system is tenfold more efficient than that of the nanoparticles themselves. The drug is observed to be widely distributed in tumor slices. Thus, this platform exhibits an efficient approach in the targeted delivery of therapeutic nanoparticles and molecules via a multistage strategy, and can be used as a potential system in co‐delivery of multiple agents for biomedical imaging and therapy.
Controlling Light Localization and Light–Matter Interactions with Nanoplasmonics
Authors: Giannini Vincenzo , Fernández‐Domínguez Antonio I. , Sonnefraud Yannick , Roschuk Tyler , Fernández‐García Roberto , Maier Stefan A.
Published: September 2010

Nanoplasmonics is the emerging research field that studies light–matter interactions mediated by resonant excitations of surface plasmons in metallic nanostructures. It allows the manipulation of the flow of light and its interaction with matter at the nanoscale (10−9 m). One of the most promising characteristics of plasmonic resonances is that they occur at frequencies corresponding to typical electronic excitations in matter. This leads to the appearance of strong interactions between localized surface plasmons and light emitters (such as molecules, dyes, or quantum dots) placed in the vicinity of metals. Recent advances in nanofabrication and the development of novel concepts in theoretical nanophotonics have opened the way to the design of structures aimed to reduce the lifetime and enhance the decay rate and quantum efficiency of available emitters. In this article, some of the most relevant experimental and theoretical achievements accomplished over the last several years are presented and analyzed.
Minimally‐invasive fetal autopsy using magnetic resonance imaging and percutaneous organ biopsies: clinical value and comparison to conventional autopsy
Authors: Breeze A. C. G. , Jessop F. A. , Set P. A. K. , Whitehead A. L. , Cross J. J. , Lomas D. J. , Hackett G. A. , Joubert I. , Lees C. C.
Published: September 2010

Objectives

Autopsy is an important investigation following fetal death or termination for fetal abnormality. Postmortem magnetic resonance imaging (MRI) can provide macroscopic information of comparable quality to that of conventional autopsy in the event of perinatal death. It does not provide tissue for histological examination, which may limit the quality of counseling for recurrence risks and elucidation of the cause of death. We sought to examine the comparability and clinical value of a combination of postmortem MRI and percutaneous fetal organ biopsies (minimally invasive autopsy (MIA)) with conventional fetal autopsy.

Methods

Forty‐four fetuses underwent postmortem MRI and attempted percutaneous biopsy (using surface landmarks) of major fetal organs (liver, lung, heart, spleen, kidney, adrenal and thymus) following fetal death or termination for abnormality, prior to conventional autopsy, which was considered the ‘gold standard’. We compared significant findings of the two examinations for both diagnostic information and clinical significance. Ancillary investigations (such as radiographs and placental histology) were regarded as common to the two forms of autopsy.

Results

In 21 cases conventional autopsy provided superior diagnostic information to that of MIA. In two cases the MIA provided superior diagnostic information to that of conventional autopsy, when autolysis prevented detailed examination of the fetal brain. In the remaining 21 cases, conventional autopsy and MIA provided equivalent diagnostic information. With regard to clinical significance, however, in 32 (72.7%) cases, the MIA provided information of at least equivalent clinical significance to that of conventional autopsy. In no case did the addition of percutaneous biopsies reveal information of additional clinical significance.

Conclusions

Although in some cases MRI may provide additional information, conventional perinatal autopsy remains the gold standard for the investigation of fetal death. The utility of adding percutaneous organ biopsies, without imaging guidance, to an MRI‐based fetal autopsy remains unproven. Postmortem MRI, combined with ancillary investigations such as placental histology, external examination by a pathologist, cytogenetics and plain radiography provided information of equivalent clinical significance in the majority of cases. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Role of three‐dimensional ultrasound measurement of the optic tract in fetuses with agenesis of the septum pellucidum
Authors: Bault J. P. , Salomon L. J. , Guibaud L. , Achiron R.
Published: September 2010

Objectives

To construct reference ranges for fetal optic tract mean diameter and to report measurements in fetuses with agenesis of the septum pellucidum (SP).

Methods

Three‐dimensional volumes of the optic chiasm were acquired in 98 normal fetuses during routine sonographic examination at 21–36 weeks' gestation and the diameters of the posterior left and right optic tracts were measured offline. A polynomial regression approach (mean and SD model) was used to compute reference charts for the mean fetal optic tract diameter measurements. In addition, 23 volumes were acquired in fetuses with SP agenesis for offline measurement of optic tract diameter. Complete follow‐up was obtained in 13 of these 23 cases.

Results

In normal fetuses, the optic tract diameter increased linearly throughout gestation. There was no evidence of increased variability with gestational age (constant SD). Normal charts and equations for Z‐score calculation were constructed. Among the 13 fetuses with SP agenesis and complete follow‐up, nine had normal measurements, of which eight had normal vision postnatally. Four had hypoplastic optic tract, defined as mean optic tract diameter Z‐score below − 3. Of these, two underwent termination of pregnancy and pathological examination confirmed hypoplasia of the tract, one showed signs of hypoplasia at magnetic resonance imaging and postnatal examination confirmed blindness, and one had a hypoplastic measurement for only one tract and was born with poor vision and abnormal bilateral eye movements.

Conclusion

We present new reference charts for mean fetal optic tract diameter. In fetuses with agenesis of the SP, sonography of the optic tract might be a useful tool to assess its development and may help in prenatal counseling. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
RNA diagnostics: real‐time RT‐PCR strategies and promising novel target RNAs
Authors: Mayer Günter , Müller Jens , Lünse Christina E.
Published: September 2010

Ribonucleic acid (RNA) is a multifunctional type of molecule, playing critical roles in protein biosynthesis and regulation. In recent years, suppression of protein translation by so‐called microRNAs came into the focus of research, especially because deregulation of this process has been shown to play a role in malignant transformation. Furthermore, RNA molecules circulating in the blood have been revealed as a novel class of markers for diagnosis of cancers. Moreover, genetic information of some pathogens is stored as RNA, allowing their sensitive detection using nucleic acid amplification techniques. In this article, the principle of detecting different RNA types by real‐time reverse‐transcription polymerase chain reaction applications is described. Furthermore, the emerging use of microRNA and circulating RNA profiles complementing the broad spectrum of RNA diagnosis is discussed. WIREs RNA 2011 2 32–41 DOI: 10.1002/wrna.46

This article is categorized under:

Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs

Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs

RNA in Disease and Development > RNA in Disease

RNA Methods > RNA Analyses In Vitro and In Silico
The tmRNA‐tagging mechanism and the control of gene expression: a review
Authors: Barends Sharief , Barend Kraal , van Wezel Gilles P.
Published: September 2010

The tmRNA‐mediatedtrans‐translation system is a unique quality control system in eubacteria that combines translational surveillance with the rescue of stalled ribosomes. Duringtrans‐translation, the chimeric tmRNA molecule—which acts as both tRNA and mRNA—is delivered to the ribosomal A site by a ribonucleoprotein complex of SmpB and EF‐Tu–GTP, allowing the stalled ribosome to switch template and resume translation on a small coding sequence inside the tmRNA molecule. As a result, the aberrant protein becomes tagged by a sequence that is a target for proteolytic degradation. Thus, the system elegantly combines ribosome recycling with a clean‐up function when triggered by truncated transcripts or rare codons. In addition, recent observations point to a specific regulation of the translation of a small number of genes by tmRNA‐mediated inhibition or stimulation. In this review, we discuss the most prominent biochemical and structural aspects oftrans‐translation and then focus on the specific role of tmRNA in stress management and cell‐cycle control of morphologically complex bacteria.WIREs RNA2011 2 233–246 DOI: 10.1002/wrna.48

This article is categorized under:

Translation > Translation Mechanisms

Translation > Translation Regulation

RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms
Bacterial/archaeal/organellar polyadenylation
Authors: Mohanty Bijoy K. , Kushner Sidney R.
Published: September 2010

Although the first poly(A) polymerase (PAP) was discovered in Escherichia coli in 1962, the study of polyadenylation in bacteria was largely ignored for the next 30 years. However, with the identification of the structural gene for E. coli PAP I in 1992, it became possible to analyze polyadenylation using both biochemical and genetic approaches. Subsequently, it has been shown that polyadenylation plays a multifunctional role in prokaryotic RNA metabolism. Although the bulk of our current understanding of prokaryotic polyadenylation comes from studies on E. coli, recent limited experiments with Cyanobacteria, organelles, and Archaea have widened our view on the diversity, complexity, and universality of the polyadenylation process. For example, the identification of polynucleotide phosphorylase (PNPase), a reversible phosphorolytic enzyme that is highly conserved in bacteria, as an additional PAP in E. coli caught everyone by surprise. In fact, PNPase has now been shown to be the source of post‐transcriptional RNA modifications in a wide range of cells of prokaryotic origin including those that lack a eubacterial PAP homolog. Accordingly, the past few years have witnessed increased interest in the mechanism and role of post‐transcriptional modifications in all species of prokaryotic origin. However, the fact that many of the poly(A) tails are very short and unstable as well as the presence of polynucleotide tails has posed significant technical challenges to the scientific community trying to unravel the mystery of polyadenylation in prokaryotes. This review discusses the current state of knowledge regarding polyadenylation and its functions in bacteria, organelles, and Archaea. WIREs RNA 2011 2 256–276 DOI: 10.1002/wrna.51

This article is categorized under:

RNA Processing > 3' End Processing

RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms

RNA Turnover and Surveillance > Regulation of RNA Stability
Chemische Entgiftung wichtiger organischer Cancerogene im Laboratorium
Authors: Martinetz Dieter
Published: September 2010

Diverse classes of chemicals can induce cancer in animals and men. A review is given on laboratory detoxification of some types of chemical carcinogens and the basic principles involved in laboratory safety.

No general techniques exist for the decontamination of such substances. Effective methods for the destruction of aflatoxins, aromatic amines, chloroethers, hydrazines, N‐nitrosamines and ‐amides, polycyclic aromatic hydrocarbons and some single substances (e.g. yperites, selected nitro compounds, azides, triazenes, dioxins, and captane, mercapto purine, thioguanine) in laboratory wastes are described. The methods preferred by the International Agency for Research on Cancer (Lyon) are especially considered.

Destruction techniques for chemical carcinogens must be efficient, complete, irreversible, rapid, reproducible, easy to perform, and the product of detoxification must be free of mutagenic and/or carcinogenic activity.
Zu einigen Problemen in der Chromatographie; Die chromatographische Auflösung
Authors: Eppert Günter
Published: September 2010

The chromatographic resolution R8 is given by the product of an efficiency term, a selectivity term, and a capacity term. In the literature, there are two common used approximation formulas for R8, which give no conformable values.

Therefore, it is reasonable to introduce a generally valid equation, for that I propose a proper mathematical expression. It shows that the capacity term is no independent term of resolution.

Using average plate numbers, the general equation is changed into the Said equation. The Said equation is a very recommendable approximation, which should be solely used in future, instead of the common used approximation formulas.

A typical function maximum exists in case of the resolution performance, which is a relevant quantity to modern chromatography.
Zur Komplexkatalyse der Aminomethylierung und Aminierung von Olefinen
Authors: Steinborn Dirk , Taube Rudolf
Published: September 2010

This review covers homogeneously catalyzed reactions of nonactivated olefines with aliphatic amines, α‐C  H bonds of amines react with olefines under addition to the C = C double bond in the presence of radical initiators and metal amides of early transition elements, respectively. According to Reppe the aminomethylation of olefines with CO/H2O and amines can be catalyzed by selected complexes of the VIII B groups elements. The N — H addition to olefinic double bonds is catalyzed by alkali metal compounds as well as by particular rhodium and iridium compounds. These amination reactions proceed by different mechanisms, probably with a β‐aminoethyl metal species being the most important intermediate. The chemistry of such β‐nitrogen substituted alkyl metal compounds is discussed with special attention being paid to the pronounced structure dependence of their stability and reactivity.
Tritiummarkierung von Steroiden
Authors: Wagner Horst , Römer Johannes
Published: September 2010

The present paper gives a survey of the prepartion of specific tritium labelled steroids of high and highest activity (up to 58 Ci/mM and 2150 GBq/mM, resp.) using the method of catalytic tritiation. It concerns steroids of all classes — androstanes, estratrienes, norandrostanes and progesterones ‐0‐‐ labelled in different positions of all the four possible rings of the steroid skeleton. The tritium labelled products have been applied in many research laboratories of the GDR and also been exported abroad.
Die Isolierung des Fluors vor 100 Jahrenendlich erreichtes Ziel und neuer Anfang
Authors: Links Dietmar
Published: September 2010

After a brief mention of the early attempts to isolate fluorine the present paper in predominantly concerned with the description of the successful Moissan experiments. Some illustrations showing the historical equipment developed by Moissan are indicative of the high accuracy characteristic for his preparation technique.

To afford an example for the international appreciation of the work done by Moissan: He was awarded the first Hofmann Prize in 1903 by the German Chemical Society. In a table are summarized also some other important data of his course of life.
Modelle molekularer Kraftfelder und ihre Anwendung in der Schwingungsspektroskopie
Authors: Böhlig Heinz , Geidel Ekkehard , Geiseler Gerhard
Published: September 2010

The concepts hitherto existing on the nature of intramolecular force fields and their physical background are presented. A short characterization of the individual force fields is followed by the description of possibilities for their application in vibrational spectroscopy. In addition to some traditional applications particularly new areas of application are outlined resulting from our present knowledge with regard to transferable force fields on the one hand and from the increasing combination of conventional and quantum chemical methods on the other. From the authors' point of view possible developments of the subject are mentioned.
Chemie der 3‐Amino‐thioacrylsäureamide; Synthesen und Eigenschaften
Authors: Liebscher Jürgen , Knoll Alexander , Abegaz Berhanu
Published: September 2010

Compounds possessing 3‐aminothioacrylamide structures have gained great interest in synthetic organic chemistry. In the present report the methods employed to synthesize 3‐aminothioacrylamides are reviewed. The classification is in accordance with the bond which is formed in the final step of the reaction sequence. A short summary of typical physical and spectroscopic properties of 3‐aminothioacrylamides is included. The wide application of 3‐aminothioacrylamides as building blocks in the synthesis of openchained and especially heterocyclic compounds will be reviewed in a separate publication.
Methanol als Substrat für biotechnische Prozesse
Authors: Babel Wolfgang
Published: September 2010

Methanol is one of the most attractive feedstocks for chemical industry. Since methanol is completely miscible with water, is easy to store, to transport and to handle, and a wide variety of microorganisms is capable of growing on methanol as the sole or major source of carbon and energy in an inexpensive synthetic medium methanol has also become attractive for the synthesis of single cell protein (SCP) and commercially useful products.

In many countries methanol assimilating microorganisms are being studied and their potential utility in biotechnological processes is explored. At present, commercial processes involving methylotrophs are limited to the production of SCP and coenzyme Q. In this review it is demonstrated that methylotrophs are suitable for syntheses of amino acids, poly‐β‐hydroxy butyric acid, enzymes and vitamins, on the one hand, and that we are far from knowing all possible applications, on the other. It gives an outline of the fundamental problems in both the SCP and overflow productions and the prospects for improving existing processes and developing novel products by means of already known organisms and new strains.
Atmosphärische Chemie — Aufgaben, Methoden und Ergebnisse
Authors: Möller Detlev , Rolle Wolfgang
Published: September 2010

The aim of atmospheric chemistry is to describe the chemical structure of the atmosphere and its dynamical behaviour. Atmospheric fluxes are the most important link within the biogeochemical cycles. The estimation of natural and man‐made related contributions to the atmospheric budget is of special interest. Owing to the biological, chemical and physical characteristics of different processes of emission reaction and distribution it is necessary to evaluate an interdisciplinary approach.

In this paper is given a short overview on different experimental and theoretical studies of chemical processes in the atmosphere. The present knowledge of the atmospheric chemistry of radicals, sulphur and nitrogen compounds as well as some selected hydrocarbon is shown.
Modelle zur quantitativen Beschreibung der Inhibition einfacher Elektrodenreaktionen durch Tensidadsorptionsschichten
Authors: Dörfler Hans‐Dieter , Emons Hendrik
Published: September 2010

Based on the theory of the absolute reaction rates and surface thermodynamics, various models describing the inhibition phenomena of simple electrode reactions by neutral surfactants at the mercury/solution interface have been discussed. These models are valid for high surface coverage (0 ≈︁ 1) and were derived under the assumption that the activated complex has the same structure at the solvent covered and at the inhibitior covered interface. The results of these models are not in agreement with experimental observations by do polarography and adsorption studies. For that reason a new model was proposed under the assumption that the activated complex is created by a surface reaction between reactant and surfactant. The comparison of the results obtained by calculations using this model with our experimental investigations shows that the different log kapp/log cA‐plots or log kapp/π‐plots (kapp: rate constant; cA: concentration of surfactant in bulk; π: surface pressure) are in a good agreement with calculations using our inhibition model. This refers to the conclusion that the models, which have been proposed in the literature are only special cases of our generalized model.
Die infrarotspektroskopische Charakterisierung von Braunsteinen
Authors: Steger Walter Eberhard , Zichner Kerstin , Lunkwitz Renate
Published: September 2010

The modifications and less defined types of manganese dioxide are considered in progressing form simple to more complex infrared spectra. The i.r. characteristic of ϵ‐MnO2 is a broad absorption from 900 to 360 cm−1. Recrystallization produces the double maximum band of tetragonal β‐MnO2 (polianit). The i.r. spectra from this modification are clearly different from those of orthorhombic β‐MnO2. Formation from and decomposition to Mn2O3 of β‐MnO2 are also studied by i.r. spectroscopy. For the recognition of γ‐MnO2 it will often be necessary to take spectra also after recrystallization of the sample by heat‐treatment.
Elektromigration von γ‐Radionukliden in homogenen wäßrigen Elektrolyten ohne Zusatz stabilisierender Träger
Authors: Rösch Frank , Chalkin Vladimir Alekseevič , Milanov Milko , Hung Tran Kim , Dreyer Rolf
Published: September 2010

The present paper give the results of tests of a special electromigration technique for the analysis of equilibrium reactions in aqueous solutions. By use the electromigration behaviour of ß‐radionuclids at ultramicroconcentrations (205,206Bi, 169Yb, 140La) can be determine hydrolysis constants and complex‐formation constants. The results are compared with results of other analytic methods. The application of this special method for electromigration measurements is discussed.
Elektronentransfer‐Kettenreaktionen in der Chemie; Organische Radikale mit Elektronendonoreigenschaften als Kettenträger: SRH1 (AH·)‐, SRH1 (A−·)‐ und SRZ1‐Kettenreaktionen
Authors: Eggert Lutz , Kuz'min Michail Georgievič , Ivanov Vladimir Leonidovič
Published: September 2010

In this paper a novel classification of chain reactions, in which participate radicals, having properties of electron donors and playing the role of chain carriers by electron transfer is offered. The reactions discussed are distinguished from classical, that means radical, chain reactions, since electron transfer processes play a decisive role in their mechanism. Three groups of chain reactions, including various types of electrondonor radicals, are turned out on the basis of a number of literature examples. In case of SRH1 (AH·)‐reactions AH· radicals, generated from a hydrogen‐atomdonor AH2, act as an electrondonor. More powerful electron‐donors than AH· are A· anion radicals in SRH1(A·)‐reactions. In SRZ1‐reactions arise radical adducts, bearing electron donor properties. In this review are also discussed some proposals for the further development of the studied chain reactions.
Biomesogene
Authors: Hoffmann Siegfried
Published: September 2010

Biomesogens evolved as an early amphiphilic pattern from the interface dialectics between order and disorder on the primordial earth. Their molecular designs provided decisive prerequisites for the projection of individual molecular facilities into the structural and functional amplifications of cooperative and dynamic mesogen domain ensembles. By directional nonlinear dynamizations, they arrived at a state of recognition and responsiveness. Competing individualizations forwarded autocatalytic propagations and information processings.

The mesogenic order‐disorder patterns gained consciousness by reality adaptation. Experiencing optimization strategies, they developed creativity. They will succeed, however, only in living responsibility.
Zum isolobalen Modell in der elementorganischen Chemie
Authors: Krause Hans‐Joachim
Published: September 2010

The present paper tries to give a survey of the isolobal model in the elementorganic chemistry. The term “isolobal” was introduced by R. Hoffmann in 1976, but the concept of the electronic relationships or electronic resemblance is older. To reconstruct the elementorganic compounds one need to know the electronic structure of the organic and inorganic fragments. For the bonding in these compounds it will suffice that we know the frontier orbitals of the fragments — in other words the valence active orbitals of each fragment. Two fragments are isolobal if number, symmetry properties, approximate energy and shape of the frontier orbitals and the number of electrons in them are similar — not identical, but similar. Hoffmann introduced a symbol for the isolobal relationship: a “two‐headed” arrow with half an orbital below. One use of the isolobal model is in the structural sense. The model allows us to see the, simple essence of seemingly complex structures. This model is also very useful in synthesis of the elementorganic compounds. In this review are discussed the fundamentals and the applications of the isolobal model.
Korrelationen beim Hydrocracken von n‐Alkanen
Authors: Hoffmann Joachim , Petzold Erich
Published: September 2010

The quantitative analysis of the product distribution in hydrocracking of n‐alkanes necessitates the consideration of a large number of reactions for which the kinetic parameters must be known. It is possible to reduce considerably the number of kinetic parameters with the help of lumping analysis. For that one can use the dependencies of the activation energy on the number of carbon atoms and the correlations of the compensation effect. The cracked product distribution can be well described by a Gaussian normal distribution. Than the splitting probability of the individual C—C‐bonds was calculated with quantumchemical methods. The experimentally obtained cracked products correspond with the charge distribution in a carbenium ion.
Struktur‐Wirkungs‐Beziehungen von Auxinen aus theoretischen Konformationsuntersuchungen und molekularen elektrostatischen Potentialen
Authors: Brandt Wolfgang , Gründler Wolfgang
Published: September 2010

New aspects of structure‐activity relationships of auxins were found by theoretical investigations of conformations and molecular electrostatic potentials. The conformation of an active compound is characterized by the formation of an intramolecular hydrogen bond between the side‐chain and the π‐electronic system of the ring part. The molecular electrostatic potentials of active molecules possess a characteristic structure different from that of inactive compounds. Even the explanation of the different behaviour in auxin action of optically active compounds is possible.
Elektrochemische Detektion in Fließsystemen
Authors: Ernons Hendrik , Jokuszies Gabriele
Published: September 2010

In the review principles and analytical applications of conductometric, potentiometric, voltammetric and coulometric detection in streaming solutions are described, with the emphasis on dynamic interfacial techniques. Sensitivity, detection limit, linear dynamic range, response time, selectivity and stability are discussed. Favourable detector cell designs are described focussing on hydrodynamic, electrochemical and stability characteristics. Practical applications of amperometric detectors are summarized. Finally most recent developments and further trends in detector research are outlined.
Ordnungsfaktoren in der organischen Synthese Kooperativität von Ordnungsfaktoren in Organischen Synthesen: eine Generalisierung der Symmetrieregeln
Authors: Heimbach Paul , Bartik Tamás , Preis Heinz‐Günther , Szczendzina Georg , Zeppenfeld Eva
Published: September 2010

Qualitative models of selforganisation of matter postulate the formation of any order out of alternatives. The important order factors in chemistry are ODD/EVEN (number), P = +1/‐1 (parity), C = +/‐ (charge) and S/AS (phase relation), from which all empirical alternative order factors like e.g. CYCLIC/OPEN, CIS/TRANS, DO/ACC and so on are derived. The importance of especially those small order factors, which are often neglected, is demonstrated by examples with an absolute effect on alternative order in structure and/or process. The cooperativity of “pairs” of — also small — order factors in the subsystems with relative inhibition/activation and compensations instead of only absolute forbidden/allowed leads to a generalisation of symmetry control in chemistry.
Zum Stand der molekültheoretischen Behandlung von organischen Laserfarbstoffen
Authors: Gustav Klaus , Colditz Roland
Published: September 2010

The calculation of molecular geometries in different electronic states, and the determination of the radiative and nonradiative behaviour of molecules are a decisive prerequisite treating organic fluorescence and laser dyes by means of molecular theory. In this paper the present possibilities of the molecular theory are discussed with regard to those properties being essential for a potential laser ability. On this basis it was attempted to propose an unified molecular theoretical model taking into account the present level of knowledge.
Enaminothioketone — Synthesen und Eigenschaften
Authors: Pulst Manfred , Greif Dieter , Kleinpeter Erich
Published: September 2010

Most important methods for the synthesis of enaminothioketones — A) sulfurization of enaminoketones; B) from β‐halogeno‐as well as β‐alkoxyvinylmethin‐immonium salts and alkali sulfides or ‐thiosulfates; C) from 1,2‐dithiolium and isothiazolium salts; D) from β‐thioxoaldehydes and amines — are described. The π‐electronic structure of the studied enaminothioketones has been investigated by means of different modes of spectroscopy (UV, IR, NMR) and characterized as polymethine‐like unsaturated organic compounds. This is proved with the obtained reactivity behaviour of the enaminothioketones as heteroanalogous 1,3‐diketones vs. eleclrophilic as well as nucleophilic attacks.
Halogenierung von Phosphorigsäurederivaten
Authors: Gloede Jöurg
Published: September 2010

Derivatives of phosphorous acids react very quickly with chlorine. The stability of adducts is depend on the groups which are bound on the phosphorus atom. Accordingly a different behaviour was observed by the halogenation of alkyl and aryl phosphites or acyclic and cyclic phosphites or saturated and unsaturated heterocyclic phosphorus compounds.
Redoxstabilität in der σ‐Organoübergangsmetallchemie
Authors: Taube Rudolf , Steinborn Dirk , Drevs Helmuth , Chuong Pham Nguyen , Stransky Norbert , Langlotz Jochen
Published: September 2010

Starting from usual principles of redox stability in coordination chemistry and from the donor‐acceptor characteristic of organyl ligands the review covers the redox behaviour of transition metals in the coordination with simple carbanions. The main topics are the stabilization of high oxidation states and the electron variability in s̀‐organyl transition metal complexes as well as the stabilization of low oxidation states, especially in electron rich phenyl complexes by coordination of lithium ions to the transition metal.
Zur Reaktion der Alkalimetalle mit Pyridin und seinen Substitutionsprodukten
Authors: Lühder Konrad , Füllbier Harry
Published: September 2010

In the present paper the reaction of alkali metals with pyridine and its substitution products is reviewed. Starting with the brutto reaction under anaerobic conditions, which yields the formation of radical anions of 4, 4′‐bipyridyl as a main product, the single steps such as formation of pyridine radical anions, dimerization of these radical anions, and, finally, the aromatization of the coupling product to the bipyridyl structure are discussed in detail.
Trennmaterialien auf der Basis von Kieselgel für die Hochleistungs‐Flüssigchromatographie
Authors: Dietrich Peter , Kunath Annamarie , Hoffmann Brigitte , Aßmann Eckhardt
Published: September 2010

At the present time amorphous porous silica is the mostly used adsorbent in the high performance liquid chromatography. This survey report about efforts in the GDR for investigations, developments and manufacturings of chemically bonded stationary phases especially of reversed phases. The quality of the stationary phases is depending on the mode of producing silica and its efficiency is a function of particle size characteristics as well as of chemical modification art.
Vinylisothiocyanate ‐ eine interessante Substanzklasse konjugierter Heterokumulene
Authors: Schulze Klaus , Schulze Bärbel , Richter Christian
Published: September 2010

Isothiocyanates having the NCS‐group bound directly to the CC‐bond — the vinyl isothiocyanates — are of high synthetic interest because this type of heterodienes is a suitable precursor for heterocyclic compounds and derivatives of thiocarbamic acid. They cannot be prepared by standard methods.

In this review we report 1) the synthesis of vinyl isothiocyanates by the reaction of nitrogen compounds with thiophosgene and other sulphur compounds, SNV‐reactions, elimination of HX, addition of HSCN to alkynes, cleavage of heterocycles and by miscellaneous methods 2) structure and reactivity of the vinyl isothiocyanates and 3) the reactions of these conjugated mustard oils with numerous nucleophiles and their behaviour as heterocumulenes in cycloaddition reactions.
Zur adsorptiven Zerlegung der Luft mit synthetischen Zeolithen
Authors: Siegel Hans , Schöllner Rolf , Hoffmann Jochen , Oehme Wolfgang
Published: September 2010

Pressure swing adsorption (PSA) processes are used to an increasing extent for gas separation. Especially the air separation for the production of low and moderate amounts of oxygen and nitrogen is more economic by PSA than by other separation processes. This paper deals with physical and chemical fundamentals of the air separation by PSA.

After introducing remarks on the increasing application of the air components for several technical purposes the adsorption properties of synthetic zeolites like sieving action, adsorption energy, kinetics, ‐equilibrium and the state of the adsorbed molecules are reported. Furthermore, technical important aspects of the influence of water preadsorption, thermal treatment of the initial zeolites and the determination of separation factors are discussed.
Oxygenierung von Kohlenwasserstoffen mit Porphyrinkomplexen
Authors: Weber Lutz , Haufe Günter
Published: September 2010

During the past ten years metalloporphyrin catalyzed oxygenations of hydrocarbons were developed by chemists, shifting from earlier normally unselective autoxidative processes to chemo‐, regio‐ and stereoselective reactions, which are oriented on enzymatic catalysis by metalloproteins. Hydroxylations of saturated as well as unsaturated hydrocarbons and epoxidations of olefins are the main topics of catalytic oxygenations using metalloporphyrins.
Metallclusterverbindungen  Chemie und Bedeutung; Homogene und heterogene Katalyse
Authors: Walther Bernhard
Published: September 2010

The interest in transition metal cluster catalysis has developed tremendously over the past decade because of the potential benefits metal cluster compounds may provide over traditional catalysts. Although these expectations have not been met yet transition metal cluster catalysis has offered many insights into the phenomenon of catalysis and still remains the most important driving force of the metal cluster chemistry. This part of the review on transition metal cluster compounds deals with the homogeneous and heterogeneous catalysis by such compounds.
Stand und Trends der Quecksilberspurenanalytik
Authors: Nitschke Lutz , Scholz Fritz , Henrion Günter
Published: September 2010

The main developments in the field of mercury analysis are traced back for the last decade. A short account of the history is given. New analytical methods and preconcentration techniques are regarded with special reference to spectrophotometry, atomic absorption spectroscopy, neutron activation analysis, voltammetry, chromatography, and catalytic analysis. Problems of sampling and applications to environmental analysis are included.
Zeugnisse aus der Gründungszeit des ersten Chemischen Laboratoriums der Berliner Universität  gefunden am 13 September 1988
Authors: Hass Dieter , Kreysig Dieter , Donke‐Müller Monika
Published: September 2010

During building and reconstruction activities in the center of Berlin was found a casket made of sheet zinc which was deposited in the foundation wall of the former Irst Chemical Laboratory of the University of Berlin in the Georgen‐Street. This casket and its content documents the laying of the foundation stone of the building by A. W.Hofmann in 1865. In the casket were found the charter of the Irst Chemical Laboratory, photos showing A. W. Hofmann, C. A. Martins and E. Sell, the register of the staff and samples of synthesized dyes. This find is very important with respect to the history of chemistry at the University of Berlin and with view on the 100th anniversary of A. W. Hofmann's death 1992 which will be celebrated by an international conference in Berlin at Humboldt‐University common with the Academy of Science and the Chemical Society of G.D.R.
Nutzungsmöglichkeiten und Grenzen von Labor‐Mikroökosystemen
Authors: Martinetz Dieter , Wenzel Klaus‐Dieter , Weißflog Ludwig
Published: September 2010

The world‐wide increase of production and application of chemicals and the question, connected with it, of protection of the environment in case of damages, disposal of wastes and sewages without any harm as well as of the minimization of the risk make necessary to find out ecochemical and ecotoxicological datas which allow a corresponding evaluation of the environment behaviour.

Possibilities are offered by terrestrial and aquatic model micro‐ecosystems which render possible to simulate chemical, physical, and biological processes of the natural environment with satisfactory reproducibility. A review is given on possibilities and limits.
Aktuelle Aspekte der ökologisch‐chemischen Bewertung von Pflanzenschutzmitteln
Authors: Beitz Horst
Published: September 2010

The use of pesticides demands the assessment of the behaviour of its residues on the treated plants and in the environment. The fate of residues is based on the biochemical degradation in plants, mikrobiological degradation in soils and the photolyzis in atmosphere, on soils and in water. Besides these factors the physical‐chemical processes play a role, such as the evaporation, the wash‐off from the plants and the leaching in deeper lagers of soil and in the groundwater.

Many models of the behaviour of residues was developed in the last years which are usual for prognoses. This is especially related to the leaching behaviour in the soil, phytotoxicity of herbicide residues, the fate of residues on plants and the uptake of residues from the soil by plants.
Zur Direktfluorierung von Oberflächen organisch‐chemischer Polymere
Authors: Uhse Eckhardt , Zimmerling Anja , Hass Dieter , Schönherr Martin
Published: September 2010

LDPE, PVF and PP films were modified by vapour phase fluorination with oxygen‐containing fluorine (5 Vol.‐% of O2) under dynamic and static conditions. Based on measurements of total acidity on the surfaces, the permeation behaviour of n‐pentane and the chemical stability of the fluorinated films the influence of oxygen on the generation of stable barrier layers was investigated. The optimal fluorine content on the surface was found to be 3 to 5% for the 30 μm thick films. The vapour phase fluorination under static conditions has to be prefered in comparison to the fluorination under dynamic conditions.
Zu einigen Problemen der Chemie des Portlandzements
Authors: Wieker Wolfgang , Herr Roland
Published: September 2010

After describing the main chemical reactions going on during the hydration of portland‐cement, the influence of small increases in the alkali‐ and sulphate content, coming from the introduction of new energy saving cementproduction processes, are discussed. By investigating pore‐ solutions squeezed from, hardened cement pastes it was shown that they contain alkalihydroxides up to 1 mol/l. These alkalihydroxide solutions react with some types of aggregates in the concrete giving alkalisilicate gels, which swell in the presence of humidity, resulting in crack formation and demolishing of the concrete constructions.

In addition to this reaction the amount of ettringite (Ca6[Al(OH)6]2 · [SO4]3 · 26H2O) formed from the cement clinker mineral 3CaO · Al2O3 is increased, because of the higher level of sulphate resulting from the fact, that most of the alkalies in the portland cement clinker are present as alkalisulphates. This ettringite is decomposed if the concrete is treated in the temperature range from 50–100°C to accelerate the hardening process. At room temperature ettringite crystallizes again which is accompanied by volume increase resulting in a deterioration of the concrete too. Possibilities to avoid the alkali‐aggregate reaction as well as the secondary ettringite formation are shown.
Latentwärmespeicher — Entwicklung und chemische Probleme
Authors: Emons Hans‐Heinz , Naumann Rüdiger , Schulz Peter , Eildermann Christine , Fülgraff Peter , Günther Andreas
Published: September 2010

Use of secondary energy sources has a growing importance to supply of energy. The utilization of corresponding heat source potentials frequently requires the adaptation of time or power difference by means of heat storage units. Recent heat storage methods are based on the utilization of reaction heats of reversible reactions or latent heats of phase transformations. Presently, latent heat storage units have the best possibilities of realization. In the range of normal temperatures between 0–120°C storage densities of 200–600 MJ/m3 are obtained on the basis of the phase change liquid‐solid at the melting point of salt hydrates. Mainly kinetic hindrances owing to phase separation, supercooling and heat transport are to be considered for application as a latent heat storage material. Internationally given solutions prefer stabilized compounds in static latent heat storage units. In contrast, with that, in the G.D.R. the dynamic latent heat storage method called „Galisol”︁ has been developed which allows optimum energy yields in narrow temperature ranges of about 10 K with high heat transfer powers. Among the developed 9 substance combinations in the temperature range between 25°C and 120°C up to now technical storage units with working temperatures of 30°C and 60°C have been realized. Various reference plants show the possibilities of application and the technical and economic advantages compared with the traditional heat storage methods.