bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal model for optimization of vascular laser tissue soldering
Authors: Bogni Serge , Stumpp Oliver , Reinert Michael , Frenz Martin
Published: March 2010

Laser tissue soldering (LTS) is a promising technique for tissue fusion based on a heat‐denaturation process of proteins. Thermal damage of the fused tissue during the laser procedure has always been an important and challenging problem. Particularly in LTS of arterial blood vessels strong heating of the endothelium should be avoided to minimize the risk of thrombosis. A precise knowledge of the temperature distribution within the vessel wall during laser irradiation is inevitable. The authors developed a finite element model (FEM) to simulate the temperature distribution within blood vessels during LTS. Temperature measurements were used to verify and calibrate the model. Different parameters such as laser power, solder absorption coefficient, thickness of the solder layer, cooling of the vessel and continuous vs. pulsed energy deposition were tested to elucidate their impact on the temperature distribution within the soldering joint in order to reduce the amount of further animal experiments. A pulsed irradiation with high laser power and high absorbing solder yields the best results. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Global changes in gene regulation demonstrate that unconjugated bilirubin is able to upregulate and activate select components of the endoplasmic reticulum stress response pathway
Authors: Oakes Garth H. , Bend John R.
Published: March 2010

Elevated concentrations of unconjugated bilirubin (UCB) are responsible for neonatal jaundice and can eventually lead to kernicterus or death. The molecular mechanism of UCB toxicity is incompletely elucidated. The purpose of this study was to analyze changes in gene regulation mediated by UCB to determine novel pathways that contribute to UCB‐mediated toxicity. We employed microarray analysis to determine changes in gene regulation mediated by UCB at both pro‐ (50 μM) and antioxidant (70 nM) concentrations in Hepa 1c1c7 cells at 1 and 6 h. The changes observed in select genes were validated with qPCR. Using immunoblot analysis, we validated these changes at the protein level for select genes and documented the activation of two proteins involved in the endoplasmic reticulum (ER) stress pathway, eIF2α and PERK. Following treatment with 50 μM UCB, microarray analysis revealed the upregulation of many genes involved in ER stress (ATF3, BiP, CHOP, Dnajb1, and Herp). We demonstrate that upregulation of the proapoptotic transcription factor CHOP results in increased intracellular protein content. It was determined that activation of proteins involved in ER stress was an early event in UCB toxicity as eIF2α and PERK were both phosphorylated and activated by 1 h posttreatment. We also demonstrate that procaspase‐12 content, a proposed initiator caspase in ER stress‐mediated apoptosis, is decreased by 4 h posttreatment. In conclusion, this study demonstrates that elevated concentrations of UCB (50 μM) are able to activate select components of the ER stress pathway in Hepa 1c1c7 cells, which may contribute to UCB‐mediated apoptosis. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:73–88, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20313
Spectroscopic investigation on the toxic interaction of melamine with herring sperm DNA
Authors: Sun Yajing , Liu Rutao , Chi Zhenxing , Qin Pengfei , Fang Xiaoyan , Mou Yue
Published: March 2010

The toxic interaction of melamine with herring sperm DNA (hs‐DNA) was investigated by using fluorescence and UV–vis absorption spectra techniques. The experimental results showed that the toxic interaction between melamine and hs‐DNA occurred. Fluorescence quenching experiments indicated the existence of electrostatic binding between melamine and hs‐DNA. The binding constantsKAand the binding site numbers were calculated by means of the Stern–Volmer equation and were 9.8 × 104L mol−1and 1.3, respectively. Both the results of fluorescence spectra and UV–vis absorption spectra verified that there are electrostatic binding between melamine and hs‐DNA. The possibility in the presence of a classical intercalation binding mode could be ruled out by using DNA unwinding experiments. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:323–329, 2010; View this article online atwileyonlinelibrary.com. DOI 10.1002/jbt.20341
Impact of East Asian winter monsoon on rainfall over southeastern China and its dynamical process
Authors: Zhou Lian‐Tong
Published: March 2010

The present study investigates the impact of the East Asian winter monsoon (EAWM) on winter (January, February, and March, or JFM in short) rainfall over southeastern China (including South China and central eastern China) and its dynamical process by using station observations for the period 1951–2003 and the ERA‐40 reanalysis for the period 1958–2002. It is found that there is a significant correlation between interannual variations of the EAWM and JFM rainfall over southeastern China. Analyses show that in weak EAWM years southwesterly anomalies at 700 hPa dominate over South China Sea, which transports more moisture into southeastern China, favouring rainfall increase. At the same time, the East Asian westerly jet weakens and displaces southward, contributing to the increase in ascending motion over southeastern China. The air temperature over southeastern China shows an obvious decrease at 300 hPa and increase near the surface. This enhances the convective instability and weakens the potential vorticity (PV), which explains the strengthening of ascending motion and the increase in JFM rainfall over southeastern China. In addition, the EAWM has impacts independent of El Niño Southern Oscillation (ENSO) on JFM rainfall over southeastern China. Moreover, the rainfall anomalies over central eastern China are more closely related to the EAWM than that in South China. Copyright © 2010 Royal Meteorological Society
Long‐term variations of circulation in the tropical Atlantic sector and Sahel rainfall
Authors: Hastenrath Stefan , Polzin Dierk
Published: March 2010

Following diagnostic work two decades ago, this study examines the long‐term variations of rainfall in the West African Sahel and the underlying circulation mechanisms over the past century. Raingauge measurements bear out DRY regimes during 1910–1919 and 1979–1988 and WET regimes during 1950–1959 and 1999–2008. In the WET as compared to the DRY regimes the cross‐equatorial winds from the Southern Hemisphere are enhanced, consistent with lower surface pressure over the tropical North Atlantic, which in terms of hydrostatic forcing plausibly accompanies warmer surface waters, with cooling/warming leading pressure rise/drop in the tropical North Atlantic and DRY/WET in the Sahel. The controls of the observed long‐term variations of sea surface temperature in the tropical North Atlantic must remain target of further diagnostic evaluation. Copyright © 2010 Royal Meteorological Society
Effect of psoralen on bone formation
Authors: Wong Ricky W.K. , Rabie A. Bakr M.
Published: March 2010

To compare the amount of new bone and bone cells produced by psoralen in collagen matrix to that produced by collagen matrix in vivo. Eighteen bone defects, 5 mm by 10 mm were created in the parietal bone of nine New Zealand White rabbits. Six defects were grafted with psoralen mixed with collagen matrix. Six defects were grafted with collagen matrix alone (negative control—collagen) and six were left empty (negative control—empty). Animals were killed on day 14 and the defects were dissected and prepared for histological assessment. Quantitative analysis of new bone formation and bone cells were made on 100 sections (50 sections for each group) using image analysis. A total of 454% more new bone was present in defects grafted with psoralen in collagen matrix than those grafted with collagen matrix. No bone was formed in the negative control—empty group. The amount of bone forming osteoblasts was also significantly greater in the psoralen group than the negative control–collagen group. Psoralen in collagen matrix has the effect of increasing new bone formation locally in vivo. Psoralen in collagen matrix can be developed as a bone graft material. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:158–164, 2011
Spatial and temporal variability of dissolved nitrous oxide in near‐surface groundwater and bubble‐mediated mass transfer to the unsaturated zone
Authors: Geistlinger Helmut , Jia Ruiyan , Eisermann Danny , Florian Stange Claus
Published: March 2010

Understanding spatial and temporal variability of dissolved nitrous oxide (N2O) is essential to process understanding of N2O emissions from near‐surface groundwater to the unsaturated zone and to the atmosphere. We propose a conceptual model of bubble‐mediated mass transfer within the exchange zone defined by the range of groundwater fluctuations. Based on this model, we discuss our experimental data collected over a period of 2 years from of a small‐scale test site (6.5 m × 2.5 m × 5 m, 20 observation wells), where we measured the dissolved gases N2O and O2 at five different depths ( 0.1, 0.5, 0.8, 1.5, and 2.5 m below groundwater level).

We show by visualization of the spatially interpolated data and by descriptive statistics that the N2O concentration of near‐surface groundwater exhibits a significant anticorrelation to O2 concentration, a spatial coefficient of variation up to 260%, and a spatial‐correlation range at the meter‐scale. The temporal variation of the spatially averaged data is correlated to the temporal variation of the averaged groundwater level. The implications of high spatial and temporal variability on gradient‐based flux models like the steady state–flat interface model usually used in literature are discussed. Our main conclusion is that both the steady‐state assumption and the flat‐interface model are far from being realistic, because of (1) the highly transient behavior of the exchange zone and (2) the oversimplification of the gas–water interface that underestimates mass transfer by order of magnitudes compared to bubble‐mediated mass transfer.
The construction of a palaeodischarge time series for use in a study of fluvial system development of the Middle to Late Pleistocene Upper Thames
Authors: Stemerdink Chris , Maddy Darrel , Bridgland David R. , Veldkamp Antonie
Published: March 2010

Recently many studies have attempted to model fluvial system development over a variety of geographical and temporal scales. It is generally recognised that one of the main problems, especially in studies over longer timescales (>100 ka), is the reconstruction of a robust palaeodischarge time series. Over such extended timescales discharge can only be reconstructed using proxy data, i.e. either field‐based (sediment) palaeodischarge estimates or transformation of reconstructed palaeoclimate data series (e.g. ice core data), with only the latter method allowing the reconstruction of a continuous time series. In this study of the Upper Thames catchment, UK, we have developed a new palaeodischarge time series. A sea surface temperature record (ODP 980) from the North Atlantic (off the west coast of Ireland) is used as a proxy for precipitation across the Upper Thames catchment. A vegetation filter, based on pollen data, is then applied to this precipitation record in order to create a runoff model. Finally, this runoff model is transformed to a discharge model via the use of a climate change function which attempts to reflect probable changes in the frequency and magnitude of discharge events. Using our new palaeodischarge model, we present output from the FLUVER2 model of longitudinal profile development for the Middle to Late Pleistocene Upper Thames Valley. This model simulates the possible timing and magnitude of sediment aggradation/degradation events on the floodplain as well as the timing of floodplain abandonment due to tectonic uplift, resulting in terrace formation. Copyright © 2010 John Wiley & Sons, Ltd.
A record of Holocene environmental and ecological changes from Wildwood Lake, Long Island, New York
Authors: Oswald W. Wyatt , Foster David R. , Doughty Elaine D. , Macdonald Dana
Published: March 2010

Analyses of pollen, charcoal and organic content in a lake sediment core from Wildwood Lake, Long Island, New York, provide insights into the ecological and environmental history of this region. The early Holocene interval of the record (ca. 9800–8800 cal. a BP) indicates the presence of Pinus rigida–Quercus ilicifolia woodlands with high fire activity. A layer of sandy sediment dating to 9200 cal. a BP may reflect a brief period of reduced water depth, consistent with widespread evidence for cold, dry conditions at that time. Two other sandy layers, bracketed by 14C dates, represent a sedimentary hiatus from ca. 8800 to 4500 cal. a BP. This discontinuity may reflect the removal of some sediment during brief periods of reduced water depth at 5300 and 4600 cal. a BP. In the upper portion of the record (<4500 cal. a BP), subtle changes at ca. 3000 cal. a BP indicate declining prevalence of Quercus–Fagus–Carya forests and increasing abundance of Pinus rigida, perhaps due to reduced summer precipitation. Elevated percentages of herbaceous taxa in the uppermost sediments represent European agricultural activities. However, unlike charcoal records from southern New England, fire activity does not increase dramatically with European settlement. These findings indicate that present‐day Pinus rigida–Quercus ilicifolia woodlands on eastern Long Island are not a legacy of recent, anthropogenic disturbances. Copyright © 2010 John Wiley & Sons, Ltd.
Portal pressure <15 mm Hg is a key for successful adult living donor liver transplantation utilizing smaller grafts than before
Authors: Ogura Yasuhiro , Hori Tomohide , El Moghazy Walid M. , Yoshizawa Atsushi , Oike Fumitaka , Mori Akira , Kaido Toshimi , Takada Yasutsugu , Uemoto Shinji
Published: March 2010

To prevent small-for-size syndrome in adult-to-adult living donor liver transplantation (A-LDLT), larger grafts (ie, right lobe grafts) have been selected in many transplant centers. However, some centers are investigating the benefits of portal pressure modulation. Five hundred sixty-six A-LDLT procedures using right or left lobe grafts were performed between 1998 and 2008. In 2006, we introduced intentional portal pressure control, and we changed the graft selection criteria to include a graft/recipient weight ratio >0.7% instead of the original value of >0.8%. All recipients were divided into period I (1998-2006, the era of unintentional portal pressure control; n = 432) and period II (2006-2008, the era of intentional portal pressure control; n = 134). The selection of small-for-size grafts increased from 7.8% to 23.9%, and the selection of left lobe grafts increased from 4.9% to 32.1%. Despite the increase in the number of smaller grafts in period II, 1-year patient survival was significantly improved (87.9% versus 76.2%). In 129 recipients in period II, portal pressure was monitored. Patients with a portal pressure <15 mm Hg demonstrated better 2-year survival (n = 86, 93.0%) than patients with a portal pressure ≥15 mm Hg (n = 43, 66.3%). The recovery from hyperbilirubinemia and coagulopathy after transplantation was significantly better in patients with a portal pressure <15 mm Hg. In conclusion, our strategy for A-LDLT has changed from larger graft–based A-LDLT to controlled portal pressure–based A-LDLT with smaller grafts. A portal pressure <15 mm Hg seems to be a key for successful A-LDLT. Liver Transpl 16:718-728, 2010. © 2010 AASLD.
Anti‐tarnish treatment of brass for coinage (II) color analysis, adsorption model, and quantum chemical calculations
Authors: Liang C. , Wang P. , Wu B. , Huang N.
Published: March 2010

The color and gloss of brass before and after anti‐tarnish treatment were analyzed with color difference meter, and the inhibition effect of 1‐phenyl‐5‐mercapto‐tetrazole (PMTA) film on brass was investigated by means of electrochemical impedance spectroscopy (EIS). It was found that the treatment with PMTA brought few changes to the original color and gloss of brass. The adsorption of PMTA on brass surface obeyed Langmuir adsorption isotherm, it was a spontaneous and exothermic process accompanied by an increase in entropy. Further, quantum chemical calculation was applied to elucidate the corrosion inhibition mechanism of PMTA on brass surface.
Very‐Low‐Bandgap Metallopolyynes of Platinum with a Cyclopentadithiophenone Ring for Organic Solar Cells Absorbing Down to the Near‐Infrared Spectral Region
Authors: Wang Xing‐Zhu , Wang Qiwei , Yan Lei , Wong Wai‐Yeung , Cheung Kai‐Yin , Ng Annie , Djurišić Aleksandra B. , Chan Wai‐Kin
Published: March 2010

Two solution‐processable metallopolyynes of platinum functionalized with the electron‐deficient 4H‐cyclopenta[2,1‐b:3,4‐b']dithiophen‐4‐one spacer and their model molecular complexes were synthesized and developed for the applications of polymer solar cells. These metallated polymers possess extremely low bandgaps of 1.44–1.53 eV which extend toward the near‐infrared (NIR) range of the solar spectrum, and represent the lowest optical bandgap yet reported for platinum(II) metallopolyynes to date. The structural flexibility, processibility, and good photovoltaic performance make cyclopentadithiophenone‐containing polymers prominent candidates for NIR photovoltaic applications.

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Price‐setting behaviour in Spain: evidence from micro PPI data
Authors: Álvarez Luis J. , Burriel Pablo , Hernando Ignacio
Published: March 2010

This paper explores the key features of manufacturing price‐setting behaviour in Spain using an extensive micro Producer Price Index data set. The main focus is placed on the impact on the frequency of price adjustment of some explanatory variables, including the cost structure, degree of market competition, demand conditions and inflationary pressures. All these factors are found to explain cross industry heterogeneity in price stickiness. A comparison of consumer and producer price‐setting practices is also presented to ascertain the role of the retail sector in explaining price stickiness. We find some evidence that producer prices are more flexible than consumer prices. Copyright © 2010 John Wiley & Sons, Ltd.
Attention deficit hyperactivity disorder: concordance of the adolescent version of the Composite International Diagnostic Interview Version 3.0 (CIDI) with the K‐SADS in the US National Comorbidity Survey Replication Adolescent (NCS‐A) supplement
Authors: Green Jennifer Greif , Avenevoli Shelli , Finkelman Matthew , Gruber Michael J. , Kessler Ronald C. , Merikangas Kathleen R. , Sampson Nancy A. , Zaslavsky Alan M.
Published: March 2010

This paper evaluates the internal consistency reliability and concurrent validity of the assessment of Diagnostic and Statistical Manual of Mental Disorders (DSM‐IV) attention deficit hyperactivity disorder (ADHD) in the adolescent version of the World Health Organization (WHO) Composite International Diagnostic Interview Version 3.0 (CIDI). The CIDI is a lay‐administered diagnostic interview that was carried out in conjunction with the US National Comorbidity Survey Adolescent Supplement, a US nationally representative survey of 10,148 adolescents and their parents. Internal consistency reliability was evaluated using factor and item response theory analyses. Concurrent validity was evaluated against diagnoses based on blinded clinician‐administered interviews. Inattention and hyperactivity‐impulsivity items loaded on separate but correlated factors, with hyperactivity and impulsivity items forming a single factor in parent reports but separate factors in youth reports. We were able to differentiate hyperactivity and impulsivity factors for parents as well by eliminating a subset who endorsed zero ADHD items from the factor analysis. Although concurrent validity was relatively weak, decomposition showed that this was due to low validity of adolescent reports. A modified CIDI diagnosis based exclusively on parent reports generated a diagnosis that had good concordance with clinical diagnoses [area under the curve (AUC) = 0.78]. Implications for assessing ADHD using the CIDI and the effect of different informants on measurement are discussed.Copyright © 2010 John Wiley & Sons, Ltd.
Grafting Polymer Brushes from Glass Fibers by Surface‐Initiated ATRP
Authors: Zhang Hongwen , Jiang Yan , Yu Qiang
Published: March 2010

Grafting of PMMA and/or PS brushes from the surface of glass fibers by SI‐ATRP has been investigated in order to achieve a controlled surface structure of the matrix. The surface composition and morphology of the modified glass fibers were analyzed by FTIR, XPS, TGA, and SEM. The results indicated that the surface composition and morphology were improved by grafting polymer after modification. The modified glass fibers were composed of an organic tube and an inorganic core. The organic content on the surface of modified glass fibers was high. GPC data of free polymer showed that the SI‐ATRP from the surface of bromine‐bound glass fibers proceeded in a controlled/“living” manner.

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Polysulfobetaines as extractants for Sr(II) ions from its aqueous solutions
Authors: Garg Godawari , Chauhan Ghanshyam S. , Ahn Jou‐Hyeon
Published: March 2010

In the present paper, we communicate sorption of Sr(II) ions on novel polysulfobetaines. N‐vinyl imidazole was modified by crosslinking it with four different crosslinkers: N,N‐methylene bisacrylamide, ethylene glycol dimethacrylate, divinyl benzene, and tripropylene glycol diacrylate. All the crosslinked networks were treated with sodium 2‐bromoethane sulfonate to obtain novel polysulfobetaines. The polymers were characterized by FTIR, elemental analysis and SEM to find evidence of network formation and quaternization. These polymers were used as Sr(II) sorbents. Sr(II) uptake was determined by using a colorimetric method using Rose Bengal anionic dye and 0.1 N HCl as the eluent. SEM‐EDS analysis of Sr(II)‐loaded polymers as well as after elution on treatment with 0.1 N HCl was recorded to ascertain the uptake of Sr(II) ions. The experimental isotherm data were analyzed using the Freundlich and Temkin equations. The experimental data also were analyzed using pseudo‐second order sorption kinetic model. Results show that the equilibrium data fit well in the Freundlich isotherm. Copyright © 2010 John Wiley & Sons, Ltd.
Bedeutung von GLP‐1 für die Glucose‐Homöostase. Entdeckung der Inkretine
Authors: Blume Henning , Wedemeyer Ralph‐Steven , Gallwitz Baptist
Published: March 2010

Bereits vor mehr als 40 Jahren wurden spezifische Kommunikationsstrukturen zwischen dem Magen‐Darm‐Trakt und den für die Stoffwechselreaktion des Körpers auf die Aufnahme von Nahrungsbestandteilen verantwortlichen Organe entdeckt. In diesem Zusammenhang kommt dem Inselapparat des endokrinen Pankreas eine entscheidende Bedeutung zu. Neben der direkten Substratstimulation und einer Reizübertragung mittels neuronaler Strukturen wurden auch gastrointestinale Hormone, die so genannten Inkretine, nachgewiesen, die vom Darm ausgesendet die Organe des intermediären Stoffwechsels auf die bevorstehende Resorption wichtiger Nahrungsbestandteile, vor allem Kohlenhydrate, vorbereiten sollen. Dennoch vergingen beinahe vier Jahrzehnte, bis aus diesen Erkenntnissen der Grundlagenforschung innovative Ansätze für therapeutische Interventionen bei Diabetes mellitus entwickelt werden konnten.
DPP‐4‐Inhibitoren in der Klinik. Therapie ohne Hypoglykämie‐Gefahr
Authors: Gallwitz Baptist
Published: March 2010

Mit den DPP‐4‐Hemmern stehen seit 2007 zugelassene orale Antidiabetika zur Verfügung, die im Gegensatz zu anderen insulinotropen Medikamenten glucoseabhängig bei Hyperglykämie die Insulinsekretion stimulieren und daher kein eigenes Hypoglykämierisiko haben. Zusätzlich hemmen sie die Glucagonsekretion und sind gewichtsneutral. DPP‐4‐Hemmer sind in Monotherapie und in Kombination mit Metformin, Glitazonen und Sulfonylharnstoffen wirksam, ihre Wirksamkeit bezüglich der Blutzuckersenkung ist mit der anderer oraler Antidiabetika vergleichbar. Zugelassen und auf dem Markt sind derzeit Sitagliptin, Saxagliptin und Vildagliptin für die Kombinationstherapie mit den oben genannten Substanzen. Die Verträglichkeit ist gut, spezifische Nebenwirkungen sind nicht bekannt. Weitere Substanzen sind im Zulassungsverfahren oder in klinischer Prüfung.
Die nicht gelösten Probleme des Diabetes Typ 2. Die diabetologische Praxis
Authors: Rüßmann Heinz‐Jürgen
Published: March 2010

Mit dem Fortschreiten des Typ‐2‐Diabetes kommt es zu einer Verschlechterung der Beta‐Zellfunktion und einer Verschlechterung von HBA1C‐Werten, Nüchternblutzucker und postprandialen Blutzuckerwerten. Die gegenwärtigen Therapien sind mit Gewichtszunahme und/oder Hypoglykämien assoziiert. Außerdem ist ein Anstieg des systolischen Blutdrucks zu sehen. Man muss sich fragen, gibt es hier eine Lösung?
Gliptine und GLP‐1‐Analoga – Aspekte der pharmazeutischen Betreuung. Die Eigenverantwortlichkeit des Patienten stärken
Authors: Wörner Wolfgang
Published: March 2010

Die Zahl der Menschen mit Diabetes mellitus nimmt in Deutschland seit Jahren zu. Trotz spürbarer Verbesserungen muss die Versorgungssituation der Diabetiker nach wie vor als unbefriedigend bezeichnet werden. Die medikamentösen Optionen wurden durch Einführung der GLP‐1‐Analoga und Gliptine wesentlich erweitert, so dass das Ziel einer “physiologischen” Therapie nähergerückt ist. Zugleich stiegen damit aber auch die Anforderungen, die an die Betreuung des Diabetikers durch den Apotheker in der öffentlichen Apotheke gestellt werden. Wenn der Apotheker sich dieser Aufgabe stellt, kann er nicht nur einen substantiellen Beitrag zur Verbesserung der Stoffwechselsituation und der Lebensqualität leisten, sondern auch prospektiv helfen, arzneimittelbezogene Probleme zu verhindern.
Nachruf: Zum Gedenken an Frau Prof. Dr. Elsa Ullmann
Authors: Lippold Bernhard , Rupprecht Herbert
Published: March 2010

Nachruf im Namen aller ehemaligen Mitarbeiter

Die ehemaligen Mitarbeiter trauern um Frau Prof. Dr. Elsa Ullmann, die am Samstag, den 24. Januar 210, in Vorfreude auf ihren 99. Geburtstag, ganz ruhig entschlafen ist.
Zweifach‐Angriff auf die Gyrase durch Simocyclinon
Authors: Holzgrabe Ulrike
Published: March 2010

Schätzungsweise 1,2 Millionen Krankenhausaufenthalte werden durch multiresistente Bakterien verursacht, insbesondere durch Methicillin‐resistente Staphylococcus aureus (MRSA). Zwar wurden in den letzten Jahren Antibiotika gegen MRSA entwickelt, wie z.B. Telavancin, Linezolid oder Tigecyclin, allerdings stammen mit Ausnahme von Linezolid alle Substanzen aus bereits bekannten Antibiotikagruppen. Deshalb und auf Grund der deutlichen Verschlechterung der Resistenzlage ist es wichtig nach neuen Wirkprinzipien zu suchen.
The role of folding in the degradation of ballistic fibers
Authors: Holmes Gale A. , Kim Jae‐Hyun , Ho Derek L. , McDonough Walter G.
Published: March 2010

Research has indicated that the folding of ballistic fibers comprising soft body armor may be a factor in the performance deterioration that has been observed. To quantify the impact of this failure mechanism on body armor performance, an apparatus was designed and built to simulate the folding that may occur in the ballistic fibers while the vest is in use. This device systematically folds woven fabric and yarns of ballistic fibers to enable an assessment of the impact of folding on ballistic fiber properties. After cycling a piece of woven poly(benzoxazole) (PBO) fabric for 80,000 cycles, a 41% reduction in both the ultimate tensile strength and strain to failure of the PBO fibers was observed. These effects were also observable in data obtained from small angle x‐ray scattering (SAXS) where the long range order of the fiber structure is changed by the folding process. Preliminary failure analysis using scanning electron microscopy (SEM) on tested fibers also revealed changes in failure morphology. POLYM. COMPOS., 2010. Published 2010 by the Society of Plastics Engineers
Polarisation auf dem Schreibtisch. Experimente mit TFT‐Flachbildschirmen
Authors: Tillmanns Andrea , Blachowicz Tomasz
Published: March 2010

In LCD‐Displays wird die Helligkeit jedes farbigen Sub‐Pixels durch die angelegte Spannung bestimmt. Diese legt die Ausrichtung der Flüssigkristallmoleküle in jedem Bildpunkt und damit die Wirkung auf das polarisierte Licht fest, das den Flüssigkristall durchdringt. TFT‐Displays, die zu den Aktiv‐Matrix‐Displays gehören, nutzen zur Verbesserung von Kontrast und Schaltzeiten Dünnschichttransistoren, mit deren Hilfe auf jedes Sub‐Pixel die gewünschte Ladung aufgebracht werden kann. Neben den ursprünglichen TN‐Displays existieren inzwischen weitere Varianten. Das Licht der TFT‐Displays lässt sich für allerlei Experimente mit polarisiertem Licht nutzen.
“Das schönste Denkmal des menschlichen Geistes”. Pierre‐Simon Laplace und die Darstellung des Weltsystems
Authors: Jacobi Manfred
Published: March 2010

Pierre Simon Laplace schuf mit seiner Darstellung des Weltsystems einen Klassiker der Wissenschaftsgeschichte. Das 1796 erstmalig erschienene Werk gestattet uns einen Einblick in das astronomische und physikalische Weltbild der damaligen Zeit. Es ist jedoch kein reines Astronomiebuch, geschrieben von einem Wissenschaftler, der selbst maßgeblich zu diesem Gebiet beigetragen hat. Vielmehr bietet es auch Einsichten in andere Disziplinen wie die Entstehung des metrischen Maßsystems. Berühmt geworden ist das Buch unter anderem durch die darin enthaltene Nebularhypothese, die eines der ältesten Modelle zur Entstehung des Sonnensystems bietet. Daneben hat Laplace bereits die Möglichkeit der Existenz Schwarzer Löcher in Betracht gezogen.
Spiele mit dem Schwerpunkt. Spielwiese
Authors: Ucke Christian , Schlichting Hans‐Joachim
Published: March 2010

Bei einigen Designer‐Haushaltsgegenständen hat das Spiel mit dem Schwerpunkt große Bedeutung. Die Salz‐ und Pfefferstreuer Ercolino haben die Form eines Stehaufmännchens und können deshalb nicht umfallen. Der Streuer Doublette kann nicht wegrollen, weil er die Form eines Zwei‐Scheiben‐Rollers besitzt. Ein Trinkbecher namens Balance steht in gefülltem Zustand gerade und neigt sich beim Austrinken durch Verschieben des Schwerpunktes zur Seite. Weinflaschen werden scheinbar schwebend gehalten.
Zilien: Mannschaftsspiel mit Molekularmotoren. Selbstorganisierte Selbstreinigung von Atmungswegen
Authors: Rička Jaro
Published: March 2010

Die Atemwege sind mit einer Schleimschicht bedeckt, die wie eine Rolltreppe permanent Schmutzpartikel aus der Lunge befördert. Für den Antrieb sorgen Flimmerhärchen (Zilien), zu Tausenden koordiniert in einer kollektiven Wellenbewegung. Wie die Koordination dieser Molekularmotoren zustande kommt, ist bislang nicht geklärt. Die Biophysik vermutet hier ein Beispiel des weit verbreiteten Phänomens der Selbstorganisation, unterstützt durch externe Steuersignale, zum Beispiel mit Calciumionen. Ein einfaches Computermodell der Biophysiker der Universität Bern illustriert und unterstützt diese Hypothese.
Eine Trenneinrichtung für Quantenpaare
Authors: Schönenberger Christian
Published: March 2010

Die Quantenmechanik erlaubt neben der Überlagerung von Zuständen auch deren Verschränkung. Das betrifft Teilchen mit Ruhemasse wie Elektronen ebenso wie masselose Photonen. Zwei Forscherteams ist es jüngst gelungen, verschränkte Elektronen in Form von Cooper‐Paaren als Quelle verschränkter Elektronen zu nutzen. Dies eröffnet neue Möglichkeiten für grundlegende Experimente zur Quantenmechanik und könnte den Weg zur Quanteninformation auf einem Chip ebnen.
Frequenzkamm beschleunigt die Spurensuche
Authors: Bernhardt Birgitta , Walz Henriette , Picqué Nathalie , Hänsch Theodor W.
Published: March 2010

Spurengase kommen ihrer Definition nach in extrem geringen Konzentrationen vor. Dennoch spielen sie in vielen Bereichen eine große Rolle, so zum Beispiel in der Klimaforschung, der Luftanalyse oder zukünftig auch beim Studium der Atmosphären von extrasolaren Planeten. In einer Kooperation mit der Universität Tokio hat unser Forscherteam am Max‐Planck‐Institut für Quantenoptik (MPQ) in Garching ein Gerät entwickelt, das Spurenstoffe besonders präzise und schnell nachweist. Hierin kommen Frequenzkämme zum Einsatz, für deren Entwicklung Theodor W. Hänsch 2005 den Physik‐Nobelpreis erhielt.
Faserlaser erzeugt einzelne Lichtschwingung
Authors: Krauss Günther , Sell Alexander , Huber Rupert , Leitenstorfer Alfred
Published: March 2010

Beim Erzeugen immer kürzerer Lichtimpulse liefern sich Wissenschaftler weltweit seit Jahren ein Wettrennen. Unserer Gruppe an der Universität Konstanz ist mit der Realisierung einer einzigen Lichtschwingung im Frequenzbereich der Telekommunikation ein weiterer Durchbruch gelungen. Die Generation dieser Impulse öffnet die Tür zu vielen neuen Experimenten in der Ultrakurzzeit‐Physik.
Figuren aus Sand
Authors: Heering Peter
Published: March 2010

Ernst Florens Friedrich Chladni (1756 – 1827) wird meistens mit der Entwicklung der Akustik in Verbindung gebracht. Manche Menschen assoziieren seinen Namen aber auch mit dem Verständnis von Meteoriten als extraterrestrische Objekte. Was für eine Person konnte sich lange Jahre mit der Herstellung und Vorführung von Staubfiguren beschäftigen und gleichzeitig astronomische Überlegungen anstellen?
Raketenantrieb und ideale Form bei Wassertieren
Authors: Rolfs Claus
Published: March 2010

“Er schwimmt wie ein Fisch im Wasser” sagt man manchmal zu einem besonders elegant schwimmenden Menschen. Dass Fische überhaupt so gewandt und schnell sind, verdanken sie unter anderem einem idealen Verhältnis von Länge zu Durchmesser. Der Tintenfisch hingegen weicht hiervon ab. Er bewegt sich stoßweise mit einem Raketenantrieb vorwärts.
The zero‐order kinetics of acetaldehyde thermal generation from polyethylene terephthalate
Authors: Halek G. W.
Published: March 2010

The thermal decomposition of polyethylene terephthalale has been examined by healing isothermally in a high‐mass reaction chamber and collecting the evolved acetaldehyde on a GC column for quantization. Kinetics were determined at lime intervals up to 1 h for temperatures 225°C, 240°C, 250°C, 260°C, 265°C, 270°C, 280°C, and 300°C. The rate of acetaldehyde evolution was found to be directly proportional to time of reaction at each temperature, thus fitting a zero‐order reaction. The Arrhenius plot of the data yielded a straight line above the melting point with a slope different from the straight line for reaction rates below the melting point. The change in slopes occurred around the crystalline melting point. The following thermodynamic values were found above and below the melting point, respectively: EA, 37.5 and 8.2 kcal/mol; ΔSA, + 1.5 and −54 e.u.; A, 0.68 × 1014 and 0.43 × 102 sec−1. Possible mechanistic implications are discussed.
High flex, ozone‐resistant polymers of higher α‐olefins
Authors: Lal Joginder , Sandstrom Paul H. , Senyek Michael L.
Published: March 2010

Ozone resistance and high flex life are some of the important features of elastomers needed in the rubber industry. EPDM, a terpolymer of ethylene, propylene, and small amounts of a nonconjugated diene, has a saturated carbon‐carbon backbone and therefore shows excellent resistance to ozone and aging, and good flex properties. However, butyl rubber (1IR) has a small amount of unsaturation in its carbon‐carbon backbone and consequently does not exhibit as good ozone resistance and aging characteristics as EPDM. We discovered a family of new rubbers named HexsynTM, which were synthesized by copolymerizing higher α‐olefins (C4‐C10) with a mixture of 4‐methyl‐ and 5‐methyl‐1,4‐hexadienes. One outstanding Hexsyn™ rubber is a copolymer of 4‐hexene and the 5‐methyl‐1,4‐hexadiene. This copolymer uniquely combines the useful properties of EPDM and butyl. Outstanding features are excellent flex life, excellent ozone resistance, good compression set resistance, and high damping.

Due to its excellent flex life, HexsynTM((hexene copolymer) has been found useful in fabricating experimental pumping diaphragms of air‐driven artificial hearts of calves and also for left ventricle assist devices. This rubber has found application as a flexing element in artificial finger joints for damaged or diseased human fingers.
Quantitative evaluation of the ion‐binding characteristics of poly(4′‐vinylbenzo‐18‐crown‐6)
Authors: Chen Cindy C. , Smith Thomas W.
Published: March 2010

We have carried out an in‐depth study of the alkali metal ion binding characteristics of a model ionophoric macromolecule, poly(4′‐vinylbenzo 18‐crown‐6), P18C6. Ion selective electrode potentiometry has been utilized to determine stability constants for complexstion of K+, Na+, and Cs+ to P18C6 in methanol/water (80/20)w. Our results show that (he intrinsic binding constants, Kn, of P18C6 towards K+C1− and Na+Cl− are identical to that of the monomeric analog, benzo‐18‐crown‐6.

In the absence of supporting electrolyte, the apparent binding constant of benzo‐18‐crown‐6 is greater than (hat of P18C6. At low tonic strength the binding of K+ to P18C6 depends strongly on the fraction of crown moieties bound. P18C6 binds K+C1− and Na+Cl− with a stoichiometry of 2 mol of crown per mole of M+ . This binding, however, is not sandwich mode. The binding of K+Cl−, K+NO3 and K+ClO4− to P18C6 in methanol/water differs significantly, with KN(K+ClO4−1 being nearly an order of magnitude greater than KN(K+Cl−). Cs+ is bound to P1SC6 with a stoichiometry of ∼3 mol of crown per mole of Cs+, and the ion is bound cooperatively in a sandwich geometry.
Mass spectrometric detection of cyclic sulfides in the polycondensation of dibromoalkanes with dithiols
Authors: Montaudo G. , Scamporrino E. , Puglisi C. , Vitalini D.
Published: March 2010

MS analysis was used to identify the cyclic oligomers formed in the polycondensation reactions of dibromoalkanes with dithiols. Cyclic oligomers with only an even number of repeating units are detected among the poly condensation reaction products.
An unusual kinetics of anionic polymerization of four‐membered lactams
Authors: Šebenda J. , Hauer J. , Svetlik J.
Published: March 2010

The anionic polymerization of α,α‐disubstituted four‐membered lactams (3‐hexyl‐3‐methyl‐2‐azetidinone, I and 3‐butyl‐3‐methyl‐2‐azetidinone, II) was found to follow a more complicated kinetics than could be expected. The apparent order of polymerization with respect to the monomer was not constant and increased from zero at the beginning of polymerization to two towards its end. Therefore, it is justified to correlate only the initial rate of polymerization with the concentrations of reactants.
Expression and function of phosphodiesterases in nitrofen‐induced congenital diaphragmatic hernia in rats
Authors: van der Horst Irene W.J.M. , Morgan Beverly , Eaton Farah , Reiss Irwin , Tibboel Dick , Thébaud Bernard
Published: March 2010

Background

Congenital diaphragmatic hernia (CDH) is an anomaly associated with pulmonary hypoplasia and pulmonary hypertension (PH). The limited efficacy of current approaches to treat PH in CDH, including inhaled nitric oxide (NO), drives the search for other therapies. Phosphodiesterases (PDEs) degrade cyclic nucleotide second messenger cAMP and cGMP downstream of NO thereby limiting the vasodilatory response to NO.

Objective

To identify therapeutic targets by cataloguing the expression and function of PDE isoforms in the pulmonary vasculature in nitrofen‐induced CDH in fetal rats.

Methods/Results

Quantitative RT‐PCR revealed PDE1–5 and PDE9 mRNA expression in pulmonary arteries (PAs) of control and nitrofen‐induced CDH term fetal rats. In this order of potency, the PDE inhibitors Sildenafil (PDE5) > EHNA (PDE2) > Rolipram (PDE4) > Cilostamide (PDE3) all dilated isolated third generation PA after pre‐constriction with the thromboxane analog U46619. Hyperoxic pre‐incubation of PAs significantly attenuated vasodilatation induced by the PDE5 inhibitor Sildenafil (65% vs. 33%,P < 0.004). CDH PAs dilated significantly less to PDE2 inhibitor EHNA compared to control (51% vs. 72%,P < 0.05). Subsequently PDE2 protein expression was higher in PAs of CDH animals.

Conclusion

Most PDE isoforms exist in the PAs of fetal rats and their inhibition causes pulmonary vasodilatation. PDE5 inhibition was the most potent vasodilator, however, there were no differences between groups. PDE5‐induced vasodilatation was attenuated by hyperoxic pre‐incubation. PDE inhibitors might be considered therapeutic targets in combination with iNO in neonates with CDH. Pediatr Pulmonol. 2010; 45:320–325. © 2010 Wiley‐Liss, Inc.
A flexible docking scheme to explore the binding selectivity of PDZ domains
Authors: Gerek Z. Nevin , Ozkan S. Banu
Published: March 2010

Modeling of protein binding site flexibility in molecular docking is still a challenging problem due to the large conformational space that needs sampling. Here, we propose a flexible receptor docking scheme: A dihedral restrained replica exchange molecular dynamics (REMD), where we incorporate the normal modes obtained by the Elastic Network Model (ENM) as dihedral restraints to speed up the search towards correct binding site conformations. To our knowledge, this is the first approach that uses ENM modes to bias REMD simulations towards binding induced fluctuations in docking studies. In our docking scheme, we first obtain the deformed structures of the unbound protein as initial conformations by moving along the binding fluctuation mode, and perform REMD using the ENM modes as dihedral restraints. Then, we generate an ensemble of multiple receptor conformations (MRCs) by clustering the lowest replica trajectory. Using ROSETTALIGAND, we dock ligands to the clustered conformations to predict the binding pose and affinity. We apply this method to postsynaptic density‐95/Dlg/ZO‐1 (PDZ) domains; whose dynamics govern their binding specificity. Our approach produces the lowest energy bound complexes with an average ligand root mean square deviation of 0.36 Å. We further test our method on (i) homologs and (ii) mutant structures of PDZ where mutations alter the binding selectivity. In both cases, our approach succeeds to predict the correct pose and the affinity of binding peptides. Overall, with this approach, we generate an ensemble of MRCs that leads to predict the binding poses and specificities of a protein complex accurately.
CTCF terminal segments are unstructured
Authors: Martinez Selena R. , Miranda JJ L.
Published: March 2010

The human CCCTC‐binding factor, CTCF, organizes and regulates transcription of the genome by colocalizing distant DNA elements on the same and even different chromosomes. This protein consists of 11 zinc fingers flanked by polypeptide segments of unknown structure and function. We purified recombinant terminal fragments and observed that both are extended, monomeric, and predominantly consist of unordered content. We thus speculate that the role of the terminal extensions, and perhaps all of CTCF, is to act as a scaffold for the assembly of other proteins on a specific binding site.
Solution structure of LC5, the CCR5‐ derived peptide for HIV‐1 inhibition
Authors: Miyamoto Kazuhide , Togiya Kayo , Kitahara Ryo , Akasaka Kazuyuki , Kuroda Yoshihiro
Published: March 2010

The synthetic peptide fragment (LC5: LRCRNEKKRHRAVRLIFTI) inhibits human immunodeficiency virus type 1 (HIV‐1) infection of MT‐4 cells. In this study, the solution structure of LC5 in SDS micelles was elucidated by using the standard 1H two‐dimensional NMR spectroscopic method along with circular dichroism and fluorescence quenching. The peptide adopts a helical structure in the C‐terminal region (residues 13–16), whereas the N‐terminal part remains unstructured. The importance of Phe17 in maintaining the structure of LC5 was demonstrated by replacing Phe17 with Ala, which resulted in the dramatic conformational change of LC5. The solution structure of LC5 elucidated in the present work provides a basis for further study of the mechanism of the inhibition of HIV‐1 infection. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Structure‐activity relationship of indolicidin, a Trp‐rich antibacterial peptide
Authors: Ando Setsuko , Mitsuyasu Keitarou , Soeda Yoshitake , Hidaka Mariko , Ito Yuki , Matsubara Kouki , Shindo Mitsuno , Uchida Yoshiki , Aoyagi Haruhiko
Published: March 2010

A series of Trp and Arg analogs of antibacterial indolicidin (Ind) was synthesized and the antimicrobial and hemolytic activities were investigated. [L9]Ind, [L11]Ind, [K8,L9]Ind and [K6, 8,L9]Ind showed desirable characteristics, exhibiting negligible hemolytic activity while keeping strong antibacterial activity. The results indicated that the Trp residue at position 11 essentially contributes to both activities and one can not be exchanged for the other, whereas the Trp residues at positions 4 and 9 play important roles in antimicrobial and hemolytic activities, respectively. The Trp residues at positions 6 and 8 play no important roles in biological activities. We then found that the retro analog of Ind showed higher antibacterial activity than Ind against both Gram‐positive and Gram‐negative bacteria but remarkably lower hemolytic activity than that of Ind. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis of disulfated peptides corresponding to the N‐terminus of chemokines receptors CXCR6 (CXCR61–20) and DARC (DARC8–42) using a sulfate‐protecting group strategy
Authors: Ali Ahmed M. , Taylor Scott D.
Published: March 2010

Tyrosine sulfation is a post translational modification that occurs on integral membrane and secreted proteins, and is required for mediating crucial biological processes. Until recently the synthesis of sTyr peptides, especially those containing multiple sTyr residues, were among the most challenging peptides to prepare. We recently described an efficient strategy for Fmoc‐based solid phase synthesis of sTyr peptides in which the sulfate group in the sTyr residue(s) is protected with a DCV group (FmocTyr(SO3DCV)OH, 1). After cleavage of the peptide from the support the DCV group is removed by hydrogenolysis. Here we demonstrate that sTyr peptides containing Met or Trp residues can be prepared using our sulfate‐protecting group strategy by preparing peptides corresponding to residues 1–20 of chemokine receptor CXCR6 and 8–42 of chemokine receptor DARC. Removing the DCV groups at the end of the syntheses was readily achieved, without any reduction of the indole ring in Trp, by performing the hydrogenolysis in the presence of triethylamine. These conditions were found to be particularly efficient for removing the DCV group and superiour to our original conditions using H2, ammonium formate, Pd/C. The presence of Met was found not to interfere with the removal of the DCV group. The use of pseudoproline dipeptides and N‐backbone protection with the 2,4‐dimethoxybenzyl group were found to be very effective tactics for preventing aggregation and aspartimide formation during the synthesis of these peptides. We also report an alternative and more cost effective synthesis of amino acid 1. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.