bluuebunny/crossref_metadata_2025 huggingface dataset:
Gadolinium‐labeled quantum dots for molecular magnetic resonance imaging: R1 versus R2 mapping
Authors: Oostendorp Marlies , Douma Kim , Hackeng Tilman M. , Post Mark J. , van Zandvoort Marc A. M. J. , Backes Walter H.
Published: May 2010

Quantum dots labeled with paramagnetic gadolinium chelates can be applied as contrast agent for preclinical molecular MRI combined with fluorescence microscopy. Besides increasing the longitudinal relaxation rate, gadolinium‐labeled quantum dots may increase the transverse relaxation rate, which might be related to their magnetic properties. Furthermore, molecular MRI experiments are primarily conducted at high magnetic fields, where longitudinal relaxation rate becomes less effective, and the use of transverse relaxation rate as a source of contrast may become attractive. Consequently, the optimal method of contrast enhancement using gadolinium‐labeled quantum dots is a priori unknown. The objective of this study was to compare longitudinal relaxation rate– and transverse relaxation rate–based contrast enhancement, proton visibility, and changes thereof induced by gadolinium‐labeled quantum dots targeted to the angiogenic vasculature of murine tumors, using in vivo longitudinal and transverse relaxation rate mapping. At a field strength of 7 T, longitudinal relaxation rate–based measures were superior to transverse relaxation rate–based measures in detecting both the level and spatial extent of contrast agent–induced relaxation rate changes. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Comparative SNR for high‐throughput mouse embryo MR microscopy
Authors: Zhang Xiaoli , Schneider Jurgen E. , Portnoy Sharon , Bhattacharya Shoumo , Henkelman R. Mark
Published: May 2010

MR microscopy is being explored as a useful imaging tool to phenotype mouse embryos due to its volume coverage with three‐dimensional isotropic resolution. However, the main limitation for mouse embryo MR microscopy is the signal‐to‐noise ratio. Large numbers of embryos are needed for phenotypic screening, making high throughput essential. Two high‐throughput imaging approaches, multi‐embryo shared‐coil (shared) and multi‐embryo individual‐coil (individual), have been developed for phenotyping mouse embryos. This study quantitatively compares the signal‐to‐noise ratio at equivalent times between these two established methods by compensating for differences that result from field strength. While the individual method provides 3.3 times as much signal‐to‐noise ratio as the shared method at equivalent conditions, it is more difficult and expensive to implement. Furthermore, the number of embryos that can be imaged concurrently is limited by the number of receiver channels. The objective of this study is to provide measured comparative data to guide choices for high‐throughput mouse embryo MR microscopy and other similar applications. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Spatially resolved assessment of serotonin‐induced bronchoconstrictive responses in the rat lung using 3He ventilation MRI under spontaneous breathing conditions
Authors: Mosbah Karim , Stupar Vasile , Berthezène Yves , Beckmann Nicolau , Crémillieux Yannick
Published: May 2010

The effect on lung ventilation of bronchoconstriction induced by serotonin (intravenous injection of 50 μg/kg of serotonin) was imaged using a hyperpolarized 3He MR ventilation protocol in spontaneously breathing rats. Lung function maps assessing airflow obstruction, a key feature in clinical pneumology, were derived from dynamic image series acquired after inhalation of 3He gas. Dynamic ventilation 3He MR images spanning a respiratory cycle were obtained using a retrospective cine image reconstruction procedure. Two parameters, defined as signal amplitude and maximum signal decay rate, were derived from the time course of the MR signal for each pixel. These parameters were averaged over regions of interest placed in the lower part of the right and left lungs and submitted to statistical analysis. A homogeneous and significant decrease of signal amplitude and maximum signal decay rate after serotonin injection was observed for each rat on the parametric color maps. The data indicate that dynamic ventilation HP 3He MRI can be used to assess, in a spatially resolved manner, the ventilation function of spontaneously breathing rats and the effects of agents eliciting short‐lasting bronchoconstriction. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Improvement of hyperemic myocardial oxygen extraction fraction estimation by a diffusion‐prepared sequence
Authors: McCommis Kyle S. , Koktzoglou Ioannis , Zhang Haosen , Goldstein Thomas A. , Northrup Benjamin E. , Li Debiao , Gropler Robert J. , Zheng Jie
Published: May 2010

Myocardial oxygen extraction fraction (OEF) during hyperemia can be estimated using a double‐inversion‐recovery‐prepared T2‐weighted black‐blood sequence. Severe irregular electrocardiogram (ECG) triggering due to elevated heart rate and/or arrhythmias may render it difficult to adequately suppress the flowing left ventricle blood signal and thus potentially cause errors in the estimates of myocardial OEF. Thus, the goal of this study was to evaluate another black‐blood technique, a diffusion‐weighted‐prepared turbo spin echo sequence for its ability to determine regional myocardial OEF during hyperemia. Control dogs and dogs with acute coronary artery stenosis were imaged with both the double‐inversion‐recovery‐ and diffusion‐weighted‐prepared turbo spin echo sequences at rest and during either dipyridamole or dobutamine hyperemia. Validation of MRI OEF estimates was performed using blood sampling from the artery and coronary sinus in control dogs. The two methods showed comparable correlations with blood sampling results (R2 = 0.9). Similar OEF estimations for all dogs were observed, except for the group of dogs with severe coronary stenosis during dobutamine stress. In these dogs, the diffusion‐weighted method provided more physiologically reasonable OEF (hyperemic OEF = 0.75 ± 0.08 versus resting OEF of 0.6) than the double‐inversion‐recovery method (hyperemic OEF = 0.56 ± 0.10). Diffusion‐weighted preparation may be a valuable alternative for more accurate oxygenation measurements during irregular ECG‐triggering. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Steadiness in plantar flexor muscles and its relation to postural sway in young and elderly adults
Authors: Kouzaki Motoki , Shinohara Minoru
Published: May 2010

To investigate the functional significance of force fluctuations during voluntary contraction with a select muscle group, we examined the association between force fluctuations during voluntary contraction with plantar flexor muscles and postural sway during quiet standing in 20 young and 20 elderly adults. Young and elderly subjects maintained a quiet standing position on a force platform. They also performed a force‐matching task with unilateral isometric plantar flexion. A positive correlation was found in young and elderly adults between the coefficient of variation (CV) of center of pressure during quiet standing and the CV of force during plantar flexion only at contraction intensities of ≤5% maximum voluntary contraction that corresponded to muscle activity during quiet standing. The electromyogram power in the medial gastrocnemius was greater in the elderly than in young adults by ∽10 HZ during quiet standing and at low contraction intensities during plantar flexion. Fluctuations in motor output during low‐intensity plantar flexion were associated with postural sway during quiet standing in both young and elderly adults. Muscle Nerve, 2010
Transgenic overexpression of laminin α1 chain in laminin α2 chain–deficient mice rescues the disease throughout the lifespan
Authors: Gawlik Kinga I. , Durbeej Madeleine
Published: May 2010

Several approaches to treat laminin α2 chain–deficient congenital muscular dystrophy (MDC1A) in mouse models have been undertaken. Most have shown promising results in young animals. However, older animals have only been characterized to some extent. Herein we analyze the lifespan of laminin α2 chain–deficient mice with transgenic overexpression of laminin α1 chain. Further outcome measures included internalized myonuclei, heart fibrosis, grip strength, and serum creatine kinase activity. We show that laminin α2‐chain–deficient animals that overexpress laminin α1 chain survive to up to 1.5–2 years of age. Furthermore, they displayed improved skeletal and heart muscle morphology, near‐normal muscle strength, and normalized creatine kinase levels. Such an improvement of the dystrophic phenotype that persists to old age has not been previously demonstrated in mice. Our findings hold promise with regard to the efficient treatment of MDC1A patients in the future. Muscle Nerve, 2010
Membranen aus dem Computer?
Authors: Hofmann Dieter
Published: May 2010

Wie gewinnt man energiesparend Sauerstoff aus Luft, reduziert die Belastung der Atemluft mit Benzol in Tankstellen und trennt Ethanol aus wässrig‐ethanolischen Gemischen ab? Diese und viele weitere Vorgänge der Stofftrennung gelingen mit Polymermembranen. Das Interesse an der Entwicklung von neuen Polymeren mit verbesserten Eigenschaften ist daher groß; ein wichtiges Werkzeug dafür ist Molecular Modelling.
Dendrimere: Das Forschungsgebiet wächst und verzweigt sich
Authors: Lüning Ulrich
Published: May 2010

Kaskadenmoleküle durch repetitive Reaktionen aufzubauen und dann gezielt zu modifizieren ‐dieser Ansatz birgt viel Potential. Dendrimere sind längst kein Thema mehr nur für die Grundlagenforschung, auch Industriefirmen haben Projekte initiiert oder bieten bereits Produkte auf Dendrimerbasis an.
bac+5: Mit Baguette, Käse und Rotwein
Authors: Krüger Anke
Published: May 2010

Frankreich als Studienort ist zwar nicht exotisch, aber gerade für Chemiker immer noch ziemlich ungewöhnlich. Dabei bietet unser größtes Nachbarland vielfältige Möglichkeiten, einen Teil des Studiums oder die gesamte Ausbildung dort zu absolvieren.
Das Phantom wurde Programm
Authors: Feil Sylvia
Published: May 2010

Das Phantom der chemischen Fakultät in Madison ist fast 40 Jahre alt. Aber es spukt nicht des Nachts durch die Räume, wohnt nicht in Katakomben. In der Hauptstadt von Wisconsin im mittleren Westen der USA geht alles mit rechten Dingen zu: Das Phantom ist für gewöhnlich ein Privatdozent. Die Universität von Wisconsin lud bereits 55 Gastprofessoren ein, von denen weit über die Hälfte aus Deutschland kamen.
Start ins zehnte Jahr
Authors: Broekaert José A. C.
Published: May 2010

Neue Erkenntnisse vermitteln, Methoden und Anwendungen kritisch bewerten, Trends in der Geräteentwicklung zeigen ‐ Themen im “Blickpunkt Analytik”
„Gene prospecting”︁ ‐ die Jagd nach Geninformation
Authors: Maelicke Alfred
Published: May 2010

Mikroarrayverfahren haben die Analyse von genetischem Material revolutioniert. Schon kann man im „Netz”︁ mit dem MGuide eine Selbstbauanleitung für einen Microarrayroboter finden. Das „gene prospecting”︁, die Suche nach Bioinformation im Land der Gene und im Stil der früheren Gold‐ und Ölsucher ist auf seinem Höhepunkt angelangt.
Elektronische Drehscheiben für die Laborversorgung
Authors: Cuggolz Ernst
Published: May 2010

Während im US‐Markt bereits einige E–Commerce‐Anbieter das Labor versorgen, fehlt in Europa noch eine Schaltstelle, die ausschließlich für den Einkauf und die Informationsvermittlung arbeitet. eLabsEurope ‐ ein neuer Anbieter mit Ambitionen ‐ startet seinen Dienst mit Venture‐Kapital und zeigt, wie ein solitäres E‐Commerce‐System arbeitet
Neue Methoden der quantitativen Fluoreszenzanalyse in der Mikroskopie
Authors: Maass Martin , Pfuhl Andreas
Published: May 2010

Für die Lokalisierung von Proteinen in Zellen eignen sich licht‐ und elektronenmikroskopische Verfahren. Dazu werden Proteine über eine Antikörperkopplung oder über die Cosysnthese eines fluoreszierenden Proteins markiert.
50 Jahre GDCh‐Mitgliedschaft ‐Wir gratulieren!
Authors: Erker Gerhard , Dieck Heindirk Tom
Published: May 2010

Im Jahre 2000 feiern zahlreiche Kolleginnen und Kollegen das goldene Jubiläum ihrer GDCh–Mitgliedschaft und damit 50 Jahre fruchtbarer und erfolgreicher Zusammenarbeit. Unseren treuen und langjährigen Mitgliedern danken wir, dass sie den Weg ins neue Millennium gemeinsam mit uns beschritten haben. Bleiben Sie noch recht lange aktiv an unserer Seite! Unsere Grüße und Glückwünsche gelten
Die Brennstoffzelle: eine Zukunftstechnologie
Authors: Friedrich Kaspar Andreas
Published: May 2010

Brennstoffzellen gelten als Schlüsselelemente einer künftigen Energieversorgung. Auf ihnen ruhen die Hoffnungen der Automobilindustrie auf schadstofffreie Motoren; sie sind aber genauso gefragt für die dezentrale, umweltfreundliche Energieversorgung von Gebäuden oder Industrieanlagen.
Chemie zwischen Effekthascherei und Sachlichkeit
Authors: Vaupel Elisabeth
Published: May 2010

Ausstellungen zur Chemie haben immer damit zu kämpfen, dass eine attraktive, publikumswirksame Präsentation von Rohstoffen, Produkten und Verfahren sehr schwer ist. Die Weltausstellungen des 19. Jahrhunderts dokumentieren dieses Problem und zeigen, dass die Interessen der Laien über Jahrzehnte ignoriert wurden.
Chemie auf der Expo: Ein Mix aus Gefühl und Wissenschaft
Authors: Guggolz Ernst
Published: May 2010

Auch für die Expo 2000 gilt: „Alles ist Chemie”︁. Deutlich wird das in Hannover im und rund ums „Chemidrom”︁ in Halle 7, im „Science Tunnel”︁ in Halle 4 und beim dreitägigen „Global Dialogue: Science & Technology ‐ Think the Future”︁. Doch die Aussteller von Auto bis Zug übergehen in Hannover und bei den weltweiten Projekten häufig ihre chemische Basis.
Chemische Sensoren in der Wassertechnologie
Authors: Nießner Reinhard
Published: May 2010

Die vermeintlich simple Matrix Wasser ist alles andere als trivial. Die enorme Vielfalt an Analyten in ihren verschiedensten Erscheinungsformen und enorm unterschiedlichen Matrixzusammensetzungen haben ein breites Vordringen von Sensoren bislang verhindert. Hoffnung auf ein höheres Anwendungs‐ und Verbreitungspotential machen die enormen Fortschritte der Chiptechnologien und der optischen Sensorik.
Gekochte Eier und Marsmännchenmarmelade
Authors: Haensler Petra
Published: May 2010

Amerika macht es vor: Um den US‐Amerikanern, vor allem den Kindern, naturwissenschaftliche Zusammenhänge näher zu bringen, hat die Bayer Corporation eine Initiative „Making Science Make Sense”︁ gestartet.
Wo liegt die Zukunft der chemischen Industrie ?
Authors: Meyer‐Galow Erhard
Published: May 2010

Die chemische Industrie wird derzeit vom Kapitalmarkt nicht gerade bevorzugt. Die Firmen der New Economy, denen die Chemie oft zum Leben verholfen hat, laufen ihr den Rang ab. In den nächsten Dekaden gibt es aber genug Raum für die Chemie, um ein Feuerwerk an Innovationen bei Produkten und Prozessen zu entzünden.
Promotion of Chemical Research Transcends National Boundaries
Authors: Schmidt Karlhenz , Chemie Referatsleiter
Published: May 2010

In the autumn of 1999, nine European national research promotion organisations took the unprecedented step of soliciting joint, transnational applications for chemical research grants. The nine also agreed upon joint evaluation of the applications, while maintaining national financing of the research. The role of this initiative by the Chairmen of European Research Councils' Chemistry Committees (CERC 3) is specifically to supplement – and not to challenge – existing programmes of the European Union (EU), the European Science Foundation (ESF) and the European Committee on Science and Technology (COST). Thirteen transnational application packages have been submitted so far by 50 working groups from eight European countries. The research is to be conducted in the highly topical fields „Topological Stereochemistry, Topological Chirality”︁ and „Molecules at Complex Surfaces: Bond Forming, Bond Breaking and Dynamics”︁.
Neurodegenerative Erkrankungen: Auslösung durch zufälligen Zelltod?
Authors: Maelicke Alfred
Published: May 2010

Auch genetisch bedingte neurodegenerative Erkrankungen brechen gewöhnlich erst in späteren Lebensphasen aus. Erfordert der Krankheitsausbruch ‐ wie bisher angenommen ‐vorausgehende kumulative Zellschädigungen oder ist er eher ein singuläres Zufallsereignis?
Chemie ‐ mach mit!
Authors: Metier Jens , Sobott Frank
Published: May 2010

Ein neuer Experimentalwettbewerb für Schülerinnen und Schüler der Sekundarstufe I will durch spielerischen Umgang mit chemischen Phänomenen das Interesse an der Chemie wecken und fördern.
www.chemie‐im‐fokus.de
Authors: Hoer Renate
Published: May 2010

Die Gesellschaft Deutscher Chemiker (GDCh) hat gemeinsam mit dem Fonds der Chemischen Industrie (FCI) eine neue Internetadresse eingerichtet, die sich speziell an Schüler richtet; www.chemie‐im‐fokus‐de.
Signalübertragung und leitende Kunststoffe
Authors: Maelicke Alfred
Published: May 2010

Mit dem Nobelpreis für Chemie wurden Arbeiten ausgezeichnet, die der Polymerchemie und der modernen Materialforschung wesentliche Impulse gegeben haben. Der Nobelpreis für Medizin oder Physiologie ist in diesem Jahr an drei Neurowissenschaftler gegangen, die grundlegende Arbeiten zur Signalübertragung im Gehirn geleistet haben.
TROSY und Co: NMR‐Methoden für die Wirkstoffentwicklung
Authors: Maurer Till
Published: May 2010

Noch dominiert die Röntgenkristallographie die Strukturbestimmung von Proteinen. Aber die hochauflösende NMR‐Spektroskopie holt auf. Die Größe der Proteine spielt für NMR‐Untersuchungen nun (fast) keine Rolle mehr: Molekulargewichte von mehr als 200 kDa sind mittlerweile im Bereich des Möglichen ‐ dank neuer Methoden, aber auch durch die technische Weiterentwicklung der NMR‐Spektrometer.
Magie, die im Kind den Chemiker weckt
Authors: Wagner Tobias , Schmidt Thomas
Published: May 2010

Experimentierkästen haben sicherlich einen nicht zu unterschätzenden Anteil am besseren Verständnis und ausgeprägteren Interesse an der Chemie in der Schule; vielleicht sind sie sogar Schuld am späteren Chemiestudium des ein oder anderen, indem sie eine Faszination am Experiment entfacht haben, die bis heute nicht mehr erloschen ist. Doch wie steht es heute um die Chemiebaukästen?
1282 chemische Bachelor‐und Master–Studiengänge in Großbritannien
Authors: Kuhnert Nikolai
Published: May 2010

Der Trend an den britischen Hochschulen geht dahin, den Master zum meistgewählten Studienabschluss zu machen und den Bachelor der fehlenden internationalen Vergleichbarkeit wegen abzuschaffen. Um die Studenten zu halten, bieten die etwa 70 Hochschulen im Fach Chemie 1282 verschiedene Studiengänge und Abschlüsse an.
Computer und Indigo ‐ Alles öko?
Authors: Gärtner Edgar
Published: May 2010

Indikatoren, mit denen sich die Umweltverträglichkeit chemischer Produkte und Methoden einschätzen lässt, unterstützen auch die Lernprozesse in den Unternehmen. Wie tragen positive Parameter für Ökoeffizienz und soziale Verträglichkeit zum Wert eines Unternehmens bei?
Teaching and Research for a Closer‐Knit Europe
Authors: Karger Gerhard
Published: May 2010

Rudolf Zahradnik, President of the Academy of Sciences of the Czech Republic – and an enthusiast when it comes to Europe – has markedly influenced the reform process in his own country. His point of view has never been limited exclusively to science but has always been part of a European vision. In the following interview, Professor Zahradnik ‐ an honorary member of the GDCh since 18th September 2000 – expresses his views on European expansion and its influence on teaching and research in the Czech Republic specifically and in Europe as a whole.
Regulatoren der Apoptose: Ziele für die Arzneimittelentwicklung
Authors: Maelicke Alfred
Published: May 2010

Der programmierte Zelltod (Apoptose) ist ein für die Entwicklung und Aufrechterhaltung eines multizellulären Organismus lebenswichtiger Mechanismus. Ausgeschaltet oder überaktiviert kann Apoptose aber auch zu schweren Erkrankungen führen. Mit dem neuen Protein Diablo/Smac ist kürzlich ein weiterer Regulator der Apoptose entdeckt worden.
Endnote 4 ‐ Jäger und Sammler
Authors: Velten Christian , Informationsdienste Scitari
Published: May 2010

Klassiker kann man nicht besser machen, behaupten viele. Die Entwickler der Literaturverwaltungssoftware Endnote beweisen das Gegenteil. Durch Implementierung von Onlinefunktionen ist Endnote zu einem Allroundtalent für Literatursuche und Literaturverwaltung geworden.
Gibt es das überhaupt: „Spezialchemikalien”︁?
Authors: Willers Yves , Jung Udo
Published: May 2010

Die Unterscheidung zwischen Basis‐ und Spezialchemikalien nimmt an Bedeutung zu, da immer mehr Chemiefirmen gegenüber den Investoren eine „Spezialchemie‐Story”︁ beanspruchen. Die Frage ist jedoch, ob ein „Spezialchemie‐Produktportfolio”︁ im Vergleich zum Chemie‐Branchenindex eine bessere Bewertung verdient.
Life–Cycle‐Management plus Technologieplattform
Authors: Hauthal Hermann G.
Published: May 2010

Mit Life ‐Cycle–Management, höherer Effizienz und einer der weltweit besten, Technologieplattformen, umfangreiche Genomics– und Bioinformatik–Kooperationen inclusive, will Bayer Pharma vorerst vor allem aus eigener Kraft weiter wachsen. In diesem Jahr werden erstmalig zehn Entwicklungskandidaten für neue Medikamente erwartet.
Mit S‐S‐reduzierendem Reagenz und CE‐LIF
Authors: Caussé E. , Malatray P. , Bayle Toulouse C. , Couderc F
Published: May 2010

Die laserinduzierte Fluoreszenz eignet sich als ein sehr schnelles Verfahren für die Detektion von Thiolen in Plasma. Es gelingt die Trennung von Homocystein und verschiedenen Thiolen, die im Metabolismus von Glutathion beteiligt sind.
Promotion ‐ und was dann? Arbeitgeber Chemische Industrie
Authors: Siekerkötter Reiner
Published: May 2010

Wie sind die Chancen für promovierte Chemiker, in der chemischen Industrie eingestellt zu werden? Welche Aufgaben übernehmen Chemiker in den Unternehmen? Gibt es spezielle Bewerbungsstrategien? Was regeln Arbeitsverträge? Welche Standards sind zumindest in der Großchemie üblich?
DNA als Konstruktionsmaterial für die Nanotechnologie
Authors: Niemeyer C.
Published: May 2010

Beflügelt durch eindrucksvolle Vorbilder aus der belebten Natur erwächst ein zunehmendes Interesse, Biomoleküle und biomimetische Aufbauprinzipien bei der Herstellung nanodimensionierter Materialien einzusetzen. Das Erbmolekül DNA ist ein besonders geeigneter Werkstoff für die Nanowissenschaften.
Katalyse heute ‐ gelingt der Brückenschlag?
Authors: Grünert Wolfgang
Published: May 2010

Das Bemühen urn Brückenschläge zwischen Grundlagenforschung und Anwendung prägt das Forschungsgeschehen in der heterogenen Katalyse. Das Vordringen des kombinatorischen Ansatzes in die heterogene Katalyse hat eher Gräben aufgerissen ‐ doch die Diskussion auf dem 12. Internationalen Katalysekongress deutet auch hier mögliche Brückenschläge an.
Nebel, Spot, Fanfare‐Wie Schüler noch Chemie lernen können
Authors: Kerk Andrea , Dücker‐Benfer Carlos , Schneppensiepe Thorsten , Müller Bernd , Calle Michael , van Eldik Rudi , Felser Claudia , Renz Franz , Tremel Wolflgang , Zimehl Ralf , Drieß Matthias
Published: May 2010

An immer mehr Chemiefachbereichen in deutschen Universitäten finden sich Professoren und Studenten, die mit viel Zeit, Fleiß und persönlichem Engagement Versuchstage, Schnupperwochenenden oder aufwendige Experimentalvorlesungen für die Öffentlichkeit und vor allem für Schüler auf die Beine stellen. Und alle verfolgen damit das gleiche Ziel: Chemie erlebbar und spannend zu machen und ihre Begeisterung für Chemie auf das Publikum zu übertragen.
„Noch haben wir keine Probleme…”︁
Authors: Schaper Iris , Matzen Matthias , Matzen Medienburo
Published: May 2010

Schon jetzt werben Professoren in Stellenanzeigen mit immer blumigeren Worten urn wissenschaftliche Nachwuchskräfte. Doch wie sehen das die Chemie‐Unternehmen? Entwickeln sie neue Werbestrategien für Hochschulabsolventen oder zeigen sie sich vom angekündigten Chemikermangel unbeeindruckt?
Biozid‐Produkte werden sicherer
Authors: Gärtner Sabine
Published: May 2010

Die EU‐Kommission hat eine Verordnung über die erste Stufe des Programms zur Überprüfung alter Wirkstoffe in Bioziden erlassen. Diese Verordnung soll dahin führen, dass in spätestens zehn Jahren nur noch überprüfte Wirkstoffe in Bioziden in Verkehr gebracht werden dürfen.
Franz Hein, Arthur Schleede, Hans Kautsky und die Anorganische Chemie in Leipzig
Authors: Beyer Lothar , Hoyer Eberhard
Published: May 2010

Hätten Sie's gewußt? Arenkomplexe, Alkalimetall‐Graphit‐Einlagerungsstrukturen und Singulett‐Sauerstoff ‐ all diese hochaktuellen Forschungsgebiete haben ihren Ursprung in der anorganischen Abteilung am Chemischen Laboratorium der Universität Leipzig.
Kurze Synthesen der Spirotryprostatine
Authors: Lindel T.
Published: May 2010

Eine 400‐L‐Kultur des Pilzes Aspergillus fumigatus lieferte nur 11 mg des neuartigen Zellcyclus‐Modulators Spirotryprostatitn B. Ein Auftrag an die organische Synthese.
Chemische Visualisierung im WorldWideWeb
Authors: Oellien Frank , Engel Thomas , Hemmer Markus C.
Published: May 2010

Wer chemische Strukturen in Webbrowsern darstellen möchte, muss diese für die speziellen Datenformate mit Plug‐ins, Java‐Applets oder Active‐X‐Controls aufrüsten. Immer mehr Plug‐ins sind eigenständige Anwendungen, die innerhalb eines Browserfensters ablaufen können.
DPMA: Mehr Prüfer gegen den Patentstau
Authors: Horn Anselm , Hauthal Hermann G.
Published: May 2010

Im 50. Jahr seines Bestehens weist das Deutsche Patent‐ und Markenamt erneut einen zweistelligen Zuwachs bei deutschen Patentanmeldungen aus. Die Chemie spielt auf den vorderen Plätzen etwas zurückhaltender mit.
Flüssigkeitstransfer im Nanoliter‐Maßstab
Authors: Wehning Heike , Rapid Pico
Published: May 2010

Ziele der Automation beim Pipettieren sind die Verkleinerung der zuverlässig dosierbaren Volumina, eine einfachere Handhabbarkeit und kostengünstigere Roboter.
A method for selecting and monitoring medication sales for surveillance of gastroenteritis
Authors: Pelat Camille , Boëlle Pierre‐Yves , Turbelin Clément , Lambert Bruno , Valleron Alain‐Jacques
Published: May 2010

Purpose

Monitoring appropriate categories of medication sales can provide early warning of certain disease outbreaks. This paper presents a methodology for choosing and monitoring medication sales relevant for the surveillance of gastroenteritis and assesses the operational characteristics of the selected medications for early warning.

Methods

Acute diarrhoea incidences in mainland France were obtained from the Sentinelles network surveillance system for the period 2000–2009. Medication sales grouped by therapeutic classes were obtained on the same period. Hierarchical clustering was used to select therapeutic classes correlating with disease incidence over the period. Alert thresholds were defined for the selected therapeutic classes. Single and multiple voter algorithms were investigated for outbreak detection based on sales crossing the thresholds. Sensitivity and specificity were calculated respective to known outbreaks periods.

Results

Four therapeutic classes were found to cluster with acute diarrhoea incidence. The therapeutic class other antiemetic and antinauseants had the best sensitivity (100%) and timeliness (1.625 weeks before official alerts), for a false alarm rate of 5%. Multiple voter algorithm was the most efficient with the rule: ‘Emit an outbreak alert when at least three therapeutic classes are over their threshold’ (sensitivity 100%, specificity 95%, timeliness 1.750 weeks before official alerts).

Conclusions

The presented method allowed selection of relevant therapeutic classes for surveillance of a specific condition. Multiple voter algorithm based on several therapeutic classes performed slightly better than the best therapeutic class alone, while improving robustness against abrupt changes occurring in a single therapeutic class. Copyright © 2010 John Wiley & Sons, Ltd.
On‐line opto‐viscoelastic analysis of polypropylene fibres using multiple‐beam Fizeau fringes in transmission and a modified creep device
Authors: Hamza Ahmad A , Sokkar Taha ZN , El‐Farahaty Kermal A , Raslan Mohammed I
Published: May 2010

A creep device attached to an automated multiple‐beam Fizeau system in transmission was modified with a designed digital ruler. This device allows on‐line measurements of fibre length during creep experiments in terms of an analogue voltage value. The influence of sustained stress values on creep deformation and optical properties (n||, n⟂ and Δn) for polypropylene (PP) fibres was studied interferometrically. The opto‐viscoelastic properties of PP fibres were determined for three different values of constant applied stress of 11.536, 18.717 and 25.905 MPa, at room temperature. Also, the variations of the cross‐sectional area and Poisson's ratio were studied during creep extensions. The compliance curves were obtained as a function of both time and applied stresses. Empirical formulae are suggested to describe the creep compliance curves for PP fibres, and the constants of these formulae were determined and described at each applied stress. A Kelvin chain was used to model the mechanical behaviour of the PP fibres under study. The effect of strain on the mean refractive indices, orientation function density and crystallinity was investigated as a result of the recorded data. Microinterferograms are given for illustration. The modified creep device with the designed digital ruler enables one to obtain instantaneous automatic accurate recording of fibre length values during creep experiments. Calculation of refractive indices, orientation function and crystallinity shows a difference in material behaviour at small stresses from that at higher stresses which may be attributed to different strain rates caused by different stresses. Copyright © 2010 Society of Chemical Industry
Autonomous damage initiated healing in a thermo‐responsive ionomer
Authors: Varley Russell John , van der Zwaag Sybrand
Published: May 2010

The partially neutralised poly[ethylene‐co‐(methacrylic acid)] copolymer Surlyn 8940® (DuPont) ionomer exhibits damage‐initiated healing during high‐energy impact. This is attributed to the hierarchical structure of ionomers, arising from the presence of ionic aggregates and hydrogen bonding. This work investigates the mechanism of this process using novel techniques developed here. The ionomer's response to penetration has been found to consist of three consecutive events: an initial elastic response, an anelastic response and pseudo‐brittle failure. In addition, the ultimate level of healing has been shown to be dependent upon the elastic response during impact as well as post‐failure viscous flow. Increasing the local temperature at impact consistently increases elastic healing, although further improvements in healing are minor once the local temperature increases beyond the melting point. Below the order‐to‐disorder transition, microscopic investigations reveal severe plastic deformation while the lack of shape memory reduces the comparative level of elastic healing. Above this temperature, healing is facilitated by elastomeric behaviour at the impact site, while above the melting point a combination of elastomeric and viscous flow dominates. This work provides for the first time evidence of the consecutive healing events occurring during high‐impact penetration for ionomers. The hierarchical structure of ionomers and its impact upon the microstructure have been shown to be critical to the process. Comparison of the mechanical response during impact with that of non‐ionic polymers further highlights this. In addition, slow relaxational processes occurring post‐impact are found to facilitate further recovery in mechanical properties. Copyright © 2010 Society of Chemical Industry
Bioconversion of dieldrin by wood‐rotting fungi and metabolite detection
Authors: Kamei Ichiro , Takagi Kazuhiro , Kondo Ryuichiro
Published: May 2010

BACKGROUND: Dieldrin is one of the most persistent organochlorine pesticides, listed as one of the 12 persistent organic pollutants in the Stockholm Convention. Although microbial degradation is an effective way to remediate environmental pollutants, reports on aerobic microbial degradation of dieldrin are limited. Wood‐rotting fungi can degrade a wide spectrum of recalcitrant organopollutants, and an attempt has been made to select wood‐rotting fungi that can degrade dieldrin, and to identify the metabolite.

RESULTS: Thirty‐four isolates of wood‐rotting fungi were investigated for their ability to degrade dieldrin. Strain YK543 degraded 39.1 ± 8.8% of dieldrin during 30 days of incubation. Phylogenetic analysis demonstrated that strain YK543 was closely related to the fungus Phlebia brevispora Nakasone TMIC33929, which has been reported as a fungus that can degrade chlorinated dioxins and polychlorinated biphenyls. 9‐Hydroxydieldrin was detected as a metabolite in the cultures of strain YK543.

CONCLUSION: It is important to select the microorganisms that degrade organic pollutants, and to identify the metabolic pathway for the development of bioremediation methods. Strain YK543 was selected as a fungus capable of degrading dieldrin. The metabolic pathway includes 9‐hydroxylation reported in rat's metabolism catalysed by liver microsomal monooxygenase. This is the first report of transformation of dieldrin to 9‐hydroxydieldrin by a microorganism. Copyright © 2010 Society of Chemical Industry
AlN substrates and epitaxy results
Authors: Helava Heikki , Chemekova Tat'jana , Avdeev Oleg , Mokhov Eugeny , Nagalyuk Sergey , Makarov Yuri , Ramm Mark
Published: May 2010

Aluminum nitride (AlN) is a true bulk‐grown native substrate for III‐nitrides. The crystals are grown by seeded physical vapor transport (PVT) using AlN seeds. AlN has high thermal conductivity (comparable to, and perhaps higher than SiC), high bulk resistivity (>1x1011 Ohm cm), high bulk‐breakdown field (7‐8 MV/cm), the highest surface acoustic wave (SAW) velocity and since it has the smallest lattice constant of the III‐nitrides all AlInGaN compositions grown on AlN are in compression, thus making it easier to grow crack‐free epitaxy. Additionally, AlN is transparent down to nearly 200 nm, making it attractive for deep UV LED structures. AlN has excellent cleavage planes making it suitable for edge‐emitting lasers and low cost manufacturing. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural differences in Mg‐doped InN – indication of polytypism
Authors: Liliental‐Weber Z. , Hawkridge M. E. , Wang X. , Yoshikawa A.
Published: May 2010

Transmission Electron Microscopy shows that the InN samples doped with either increasing or constant Mg concentration follow a cation or anion substrate polarity. In‐polar samples change growth polarity when the Mg concentration is >1019cm‐3. N‐polar samples have much higher density of planar defects than In‐polar samples and their presence leads to a decrease in dislocation density. In the N‐polar samples equally spaced planar defects are observed for Mg concentration >1019cm‐3. Three different polytypes (2H, 3C and 4H) were observed in this type of samples. A band of planar defects with thick layers of a cubic material (3C) is observed for Mg concentration >1020cm‐3. At this Mg concentration only n‐type conductivity was reported earlier. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A precise ray tracing simulation model for GaN based light emitting diodes
Authors: Yang Zhiyuan , Yu Tongjun , Mu Sen , Chen Zhizhong , Zhang Guoyi
Published: May 2010

A simulation model for light extraction efficiency (LEE) was proposed, considering the real structure of GaN_based light emitting diodes and absorption of GaN, electrodes and encapsulation materials, as well as the difference between TE and TM modes, the effects of active layer reabsoption and photo recycling. The slope angle and the depth of the pattern were optimized for patterned sapphire substrates (PSSs). Results show fill factor affects the LEE improvement most and air holes buried in the interface between n‐GaN and PSS diminish LEE improvement of the pattern. Then a best improvement of 26% is obtained with the optimized pattern. Especially it is noticeable that the simulated result of LEE (39.2%) and the derived internal quantum efficiency (43.9%) agree well with the experimental results (38%, 45.1% respectively). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Internal quantum efficiency of GaN/AlGaN‐based multi quantum wells on different dislocation densities underlying layers
Authors: Takeda Kenichiro , Mori Fumiaki , Ogiso Yuji , Ichikawa Tomoaki , Nonaka Kentaro , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu
Published: May 2010

Internal quantum efficiency (IQE) of GaN/AlGaN multi quantum wells on the low dislocation density Al0.25Ga0.75N grown by epitaxial lateral overgrowth (ELO) and facet controlled epitaxial lateral overgrowth were investigated by excitation intensity dependent photoluminescence measurement. The threading dislocation density decreased from 4x109cm‐2 to 2x108cm‐2 by using ELO method, then the IQE was much improved from 5% to 40% when the carrier density was 1x1018cm‐3. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of trapping effects in AlGaN/GaN HEMTs based on near zero bias output conductance
Authors: Kim Hyeongnam , Lu Wu
Published: May 2010

A simple model is developed for characterization of current collapse caused by electron trapping in AlGaN/GaN HEMTs. Threshold voltages are extracted from near‐zero drain bias output conductance characteristics with respect to gate bias based on 0.2 μs pulsed I –V characteristics at different quiescent bias points. Other device parameters such as effective gate length and electron mobility are also estimated by fitting to a model equation. The results show that a higher negative electric field between gate and drain contacts cause a higher threshold voltage shift in the positive direction and a longer effective gate length, resulting in a larger current dispersion due to trapping of more electrons. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characterization of n ‐GaN epilayers using transparent polyaniline Schottky contacts
Authors: Nakano Yoshitaka , Matsuki Nobuyuki , Irokawa Yoshihiro , Sumiya Masatomo
Published: May 2010

We have successfully investigated deep levels of n ‐GaN epilayers with high carrier concentrations by using transparent polyaniline Schottky conctacts. High quality Schottky barrier diodes fabricated showed a capacitance dispersion phenomenon at ∼10 kHz, which is characteristic of polyaniline. Deep‐level optical spectroscopy measurements above this cutoff frequency newly revealed a specific deep levels located at ∼1.70 eV below the conduction band, being different from the deep levels commonly observed in GaN. This deep level showed a significant increase in steady‐state photocapacitance with a decrease in probing depth range. Therefore, the 1.70 eV level probably stems from the near‐surface region of the n ‐GaN rather than the bulk region. This is the abstract. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carrier injection in InAlGaN single and multi‐quantum‐well ultraviolet light emitting diodes
Authors: Kolbe Tim , Sembdner Toni , Knauer Arne , Kueller Viola , Rodriguez Hernan , Einfeldt Sven , Vogt Patrick , Weyers Markus , Kneissl Michael
Published: May 2010

316 nm (In)AlGaN light emitting diodes (LEDs) with one, three, five and seven quantum wells (QWs) have been investigated. The carrier injection in the devices is simulated and compared with electroluminescence measurements. The emission power of all LEDs is nearly the same at low currents. This effect is attributed to the inhomogeneous carrier distribution in the QWs of the multi‐quantum‐well (MQW) structures. Only the first two QWs closest to the p‐side of the diode contribute significantly to the optical emission (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reducing the warpage and dislocation density of GaN template grown by HVPE with gallium droplet treatment
Authors: Choi Young Jun , Oh Hae‐Kon , Kim Jung‐Gyu , Hwang Hyun‐Hee , Lee Hae‐Yong , Lee Won‐Jae , Shin Byoung‐Chul , Hwang Jonghee
Published: May 2010

The warpage of the GaN template grown by a HVPE with gallium droplet treatment (GDT) was 13.8 μm, which was reduced by 80.3% of the warpage for GaN template grown by conventional MOCVD and 43% of the warpage for GaN template grown by HVPE without GDT. The treatment of gallium droplets on sapphire was achieved by thermal evaporator at room temperature. The E2 high peak of GaN template with GDT showed at 566.5 cm‐1, whereas the E2 high peak of GaN template by MOCVD positioned at 569.5 cm‐1 in Raman scattering spectra. According to the frequency shifts of E2 high peak position for each template around 3 cm‐1, the release of compressive stress of GaN template grown by HVPE with GDT was shown. In study of FE‐SEM and Grow discharge spectroscopy (GDS), voids and concentration decline zones of gallium and aluminium in counter direction were formed at the interface between GaN epilayer and sapphire substrate during GaN growth by HVPE. We expected that the decrease of warpage and stress for GaN template with GDT could be caused by the formation of voids and concentration decline zones of gallium and aluminium. Etch pits density of GaN template with GDT was around 8.5x107/cm2. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis and evaluation of large‐scale river restoration planning in Germany to better link river research and management
Authors: Kail J. , Wolter C.
Published: May 2010

In December 2008, the draft programmes of measures (PoM) have been published in the EU member states, which list the measures that will be taken to enhance the ecological status of surface and groundwater bodies, and to reach the environmental objectives of the EU‐Water Framework Directive (WFD). We have analysed the German PoM to identify the main pressures and the restoration measures water managers planned to implement in streams and rivers. The objective was to evaluate the PoM and to identify the main, practically relevant knowledge gaps in river management on which applied river research should focus on.

In general, the selection of measures in the PoM was reasonable. In accordance with the analysis of pressures and impacts in Germany, the PoM focussed on measures addressing morphological alterations and river continuity, and the results indicated that diffuse source pollution and fine sediment input were additional main pressures in Central European streams and rivers. Although point source pollution was not a main pressure in most rivers, respective point source measures have been selected for many water bodies. Apparently, these were so‐called basic measures that have to be taken due to other EU‐Directives or national laws. Therefore, although in line with the WFD, it seemed doubtful if the point source measures would help to substantially enhance the ecological status. Furthermore, the results indicated that there was a general lack of knowledge on the effect of restoration measures and a specific knowledge gap in how to enhance the ecological state of heavily modified water bodies (HMWB) in the lowland region with a high land‐use pressure, which was reflected by the high share of water bodies for which conceptual measures have been selected (e.g. developing management plans).

Based on the analysis of the PoM and a literature review, we identified the following, practically relevant knowledge gaps in river management: (i) the morphodynamics of river reaches where natural channel dynamics have been restored, (ii) the combined effect of measures addressing diffuse nutrient and fine sediment input at different spatial scales (e.g. riparian buffer strips and land‐use changes), (iii) methods to identify suitable and efficient measures and to define environmental objectives for HMWB and (iv) the effect of measures on less well‐studied biological groups like macrophytes and phytoplankton. There is a strong need to summarize recent research results on these issues, to identify the knowledge gaps and research needs in detail, and to make the results of such a comprehensive literature review or meta‐analysis available for the next 6‐year management cycle and second WFD management plans. Copyright © 2010 John Wiley & Sons, Ltd.
Land‐use effects on water quality of a first‐order stream in the Ozark Highlands, mid‐southern United States
Authors: Brion G. , Brye K. R. , Haggard B.E. , West C. , Brahana J.V.
Published: May 2010

Urban and agricultural land uses can alter the natural hydrologic conditions of streams and rivers and often degrade water quality. In the Ozark Highlands of the mid‐southern United States, the climate, topography, soil properties, karst limestone geology, agricultural practices and rapid urbanization make water quality of particular concern due to the increased potential for water quality degradation by contaminant leaching to groundwater and runoff to surface waters. The objective of this study was to evaluate the effects of season (i.e. dry/cool and wet/warm) and riparian land use (i.e. urban, grazed pasture, ungrazed pasture, wetland, cultivated agriculture and grassland) on surface water quality in a first‐order stream within a diverse agricultural watershed in the Ozark Highlands. Water samples were collected twice a month within each land use during base‐flow conditions from October 2006 through October 2007. Samples were also collected periodically during storm‐flow conditions from October 2006 through December 2007. The greatest in‐stream pH was adjacent to the grazed pasture. In‐stream NO3‐N concentrations were greatest adjacent to the cultivated agriculture and grassland during the dry/cool season (i.e. October 2006 to March 2007) and averaged 2.67 mg L−1. In‐stream soluble reactive P (SRP) concentrations were greatest adjacent to the grassland during the wet/warm season (i.e. April 2007 to October 2007) and averaged 0.81 mg L−1. Concentrations of SRP, K, Mg and Zn were greater during storm‐ than base‐flow conditions and in‐stream As concentrations frequently exceeded 0.01 mg L−1. Discharge and in‐stream NH4‐N concentrations were unaffected by land use or season and averaged 0.003 m3 s−1 and 0.10 mg L−1, respectively, across all land uses and seasons. Results of this study clearly demonstrate the significant effect of adjacent land use on in‐stream water quality of a first‐order stream in a diverse agricultural watershed and highlight the importance of managing upstream land use in order to regulate downstream water quality. Copyright © 2010 John Wiley & Sons, Ltd.
Surface characterisation of boron nitride layers on multiwalled carbon nanotubes
Authors: Mohai M. , Mohai I. , Sebestyén Z. , Gergely A. , Németh P. , Szépvölgyi J.
Published: May 2010

Multiwalled carbon nanotubes (MWCNTs), because of their unique morphology and physico‐chemical properties, have many potential advantages in nanotechnology, electronics, optics and other fields of material science. Their use is limited by their sensibility to oxidation, especially at high temperatures. The chemical resistance of MWCNTs could be increased by coating with non‐oxides, e.g. boron nitride (BN) layers. The aim of the present work was to study the formation of BN thin films on MWCNTs by thermal treatment. Thin films of BN were deposited on MWCNTs surfaces by dip coating of boric acid solutions and high temperature nitriding in ammonia flow. Surface composition and chemical states of the layers were determined by X‐ray photoelectron spectroscopy. The surface layer thickness was also calculated based on XPS data, applying the Layers‐on‐Cylinder model of the XPS MultiQuant program. Resistance of the coated MWCNTs against high temperature oxidation was tested by thermogravimetric analysis. The morphology was investigated by transmission electron microscopy. Copyright © 2010 John Wiley & Sons, Ltd.