bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calculation Approach for Ceramic Heat Pipe‐Heat Exchanger for High‐Temperature Applications
Authors: Unz Simon , Hack Nina , Beckmann Michael 
Published: November 2017

AbstractMetallische Werkstoffe weisen bei hohen Temperaturen und chemisch aggressiven Atmosphären geringe Standzeiten auf. Eine Alternative sind keramische Werkstoffe, die jedoch nicht wie metallische Werkstoffe verarbeitet werden können. Deshalb wird der Einsatz einer einfachen Wärmerohrgeometrie als Grundform für Wärmeübertragungssysteme in der Hochtemperaturtechnik betrachtet. Zur Auslegung von Hochtemperaturwärmeübertragern wird ein numerisches Berechnungsmodell zur genauen Bestimmung des Betriebsverhaltens großer Apparate vorgestellt, das neben konvektivem auch den strahlungsabhängigen Wärmetransport berücksichtigt.
Sicherer Umgang mit Kanülen – von Erfahrungen zu Evidenzen
Authors: Sieve Bernhard F. , Taubert Christin , Taubert Richard 
Published: November 2017

AbstractMedizintechnische Geräte gehören mittlerweile an vielen Schulen zum experimentellen Repertoire. Von den dabei verwendeten spitzen Kanülen geht jedoch ein nicht zu vernachlässigendes Verletzungsrisiko aus, weshalb in der Experimentierliteratur verschiedene und allesamt auf persönlichen Erfahrungen beruhende Empfehlungen zur „Entschärfung“ von Kanülen existieren. In diesem Beitrag werden die Ergebnisse einer reproduzierbaren Testung des Gefährdungspotentials von auf verschiedene Weise abgestumpften Kanülen in Bezug auf Stich‐ und Schnitt‐ bzw. Rissverletzungen vorgestellt. Aus den Ergebnissen werden evidenzbasierte Empfehlungen für die Nutzung von Kanülen im Chemieunterricht abgeleitet.
Untersuchungen zum Silber‐Zink‐Akkumulator
Authors: Jakob Birgit , Habekost Achim 
Published: November 2017

AbstractDer Silber‐Zink Akku ist ein recht teurer Akkumulator mit zudem geringer Lebensdauer, er besitzt aber eine sehr hohe Kapazität bei geringem Volumen und Gewicht. Die Leerlaufspannung einer Zelle beträgt 1,5 Volt. Der Akku spielt wegen seiner Robustheit vor allem bei der Marine und in der Raumfahrt eine große Rolle. Auch aus didaktischen Gründen ist der Silber‐Zink Akku interessant, denn die Änderungen an der Silberelektrode sind gut optisch zu beobachten und messtechnisch mit einfachen Mitteln zu verfolgen. Zudem sind die Elektrodenvorgänge intensiv untersucht worden und gut verstanden und daher eindeutig beschreibbar.
Der Einsatz von Modellen zum Erkenntnisgewinn / Eine Unterrichtseinheit zur Förderung der Modellkompetenz im Kontext „Batterie“ unter explizitem Einbezug von Schülervorstellungen
Authors: Caspari Ira , Weber‐Peukert Gisela , Graulich Nicole 
Published: November 2017

AbstractDie Modellkompetenz bedarf als Standbein der Erkenntnisgewinnung einer gezielten Förderung im naturwissenschaftlichen Unterricht. Angelehnt an ein Modell der Modellkompetenz aus der Biologiedidaktik liefert die hier skizzierte Unterrichtskonzeption ein praxiserprobtes Beispiel, wie dies im Chemieunterricht umgesetzt werden kann. Ausgehend von phänomenologischen Betrachtungen des Leitungsmechanismus im Elektrolyten und der chemischen Abläufe in handelsüblichen Batterien entwickeln Lernende eigene Modelle, denen alternative Schülervorstellungen und ‐konzepte zugrunde liegen. Darauf basierend stellen die Lernenden Hypothesen über das jeweilige Original auf. Durch das experimentelle Überprüfen können schülereigene Hypothesen und Modelle und gleichzeitig die zugrunde liegenden Vorstellungen bestätigt oder falsifiziert und geändert werden. So gelingt es in dieser Unterrichtskonzeption, die Förderung der Modellkompetenz und den Umgang mit Schülervorstellungen lernförderlich zu kombinieren.
E‐Diazocine in Chemical Education: Synthesis, Structure, Photochromism and Thermal Stability
Authors: Krämer René , Nöthling Nils , Lehmann Christian W. , Mohr Fabian , Tausch Michael W. 
Published: November 2017

AbstractZ‐diazocine, synthesized as described by Tellkamp, has been photochemically converted into E‐diazocine by irradiation of its solution at λ=365 nm. After purification, single crystals of E‐diazocine were obtained by recrystallization at −18 °C from n‐pentane. The title compound was characterized by NMR spectroscopy and X‐ray crystallography. For its thermal isomerization into the more stable Z‐isomer, the thermal half‐life was determined by UV/Vis absorption studies. Furthermore, the photochemical behaviour of the compound in the solid state has been investigated.
Effects of Surface Tension Driven Convection Upon Crystal Growth of KTa1‐xNbxO3
Authors: Li Shuhui , Pan Xiuhong , Liu Yan , Jin Weiqing , Zhang Minghui , Gai Lijun , Lei Lei , Deng Weijie , Chen Kun 
Published: November 2017

AbstractThe surface tension driven convection, together with the rotating crystal growth process of potassium tantalate niobate (KTa1‐xNbxO3, KTN) crystals from unstirred melt has been carried out in a high temperature in‐situ observation system. The streamline of the stable convection is found to be in the form of a double loop axially symmetric vortices, which causes the rotation during KTN crystals growth process. The effect of surface tension convection on interfacial heat, mass and momentum transfer are investigated experimentally. The dimensionless parameters of the three transports are calculated. For KTN crystals, velocity and temperature boundary layers are pointless. Solute transfer is the main form of interface transport during crystal growth process. The effect of Nb content x on boundary layer thickness is discussed. There is a critical Marangoni Number . When , the concentration boundary layer becomes thinner with the increase of x as a result of weakened segregation effect. When , a thicker boundary layer emerges due to slower growth velocity under higher Nb contents. When , the influence of the two is comparable and the boundary layer can maintain a relatively steady value under different components.
Hydrogen Evolution by FeIII Molecular Electrocatalysts Interconverting between Mono and Di‐Nuclear Structures in Aqueous Phase
Authors: Tagliapietra Mirko , Squarcina Andrea , Hickey Neal , De Zorzi Rita , Geremia Silvano , Sartorel Andrea , Bonchio Marcella 
Published: November 2017

AbstractA new FeL/Fe2L2 manifold, with HL=2‐({[di(2‐pyridyl)methyl](methyl)amino}methyl)phenol, was prepared in gram scale (>50 % yield) and characterized in solution and solid state. The monomer/dimer interconversion is controlled in aqueous phase, upon varying the pH conditions. The electrocatalytic hydrogen evolution reaction (HER) occurs through the FeL monomer with added trifluoroacetic acid (TFA) and through the Fe2L2 μ‐oxo dimer in acetate buffer (pH 4.9), with an overpotential of about 1 V and faradaic yield up to 75 %. The resulting icat/ip values in the range 15–28 are among the highest reported for Fe‐based electrocatalysts (icat is the catalytic current, whereas ip is the current of an Fe‐based redox event).
Initial Application of Selected‐Ion Flow‐Tube Mass Spectrometry to Real‐Time Product Detection in Electrochemical CO2 Reduction
Authors: Lobaccaro Peter , Mandal Lily , Motapothula Mallikarjuna Rao , Sherburne Matthew , Martin Jens , Venkatesan T. , Ager Joel W. 
Published: November 2017

AbstractElectrochemical CO2 reduction (EC‐CO2R) has seen a resurgence in interest over the past several years; however, the means of analyzing catalytically produced products continues to rely on decades‐old methods such as gas chromatography, high‐performance liquid chromatography, and nuclear magnetic resonance. Real‐time analysis of the gaseous and liquid products of this reaction is highly desirable; however, few analytical techniques have been developed thus far to meet this need. Here, we demonstrate the first use of selected‐ion flow‐tube mass spectrometry (SIFT‐MS) as an analytical tool capable of measuring in real time both the gas‐ and liquid‐phase products of EC‐CO2R in aqueous solution. SIFT‐MS uses well‐understood ion–molecule reactions to enable the analysis of similar multicomponent mixtures by preventing substantial fragmentation of the analyte. We lay out the framework in which to evaluate the tool's capabilities and show that the C1–C3 hydrocarbon, alcohol, and aldehyde products of CO2R should be quantitatively detectable.
Phenotypic responses in Caenorhabditis elegans following chronic low-level exposures to inorganic and organic compounds
Authors: Mugova Fidelis , Read Daniel S. , Riding Matthew J. , Martin Francis L. , Tyne William , Svendsen Claus , Spurgeon David 
Published: November 2017

Abstract

Responses of organisms to sublethal exposure of environmental stressors can be difficult to detect. We investigated phenotypic changes in the tissue of Caenorhabditis elegans via Raman spectroscopy, as well as survival and reproductive output when exposed to chronic low doses of metals (copper, zinc, or silver), an herbicide (diuron), and a pesticide (imidacloprid). Raman spectroscopy measures changes in phenotype by providing information about the molecular composition and relative abundance of biomolecules. Multivariate analysis was used to evaluate the significance of treatment phenotype segregation plots compared with controls. Dose-dependent responses were observed for copper, zinc, silver, and diuron, whereas imidacloprid exposure resulted in a small response over the tested concentrations. Concentration-dependent shifts in nematode biomolecular phenotype were observed for copper. Despite having a dose–dependent reproductive response, silver, diuron, and imidacloprid produced inconsistent biological phenotype patterns. In contrast, there was a clear stepwise change between low concentrations (0.00625–0.5 mg/L) and higher concentration (1–2 mg/L) of ionic zinc. The findings demonstrate that measuring phenotypic responses via Raman spectroscopy can provide insights into the biomolecular mechanisms of toxicity. Despite the lack of consistency between survival and Raman-measured phenotypic changes, the results support the effectiveness of Raman spectroscopy and multivariate analysis to detect sublethal responses of chemicals in whole organisms and to identify toxic effect thresholds. Environ Toxicol Chem 2018;37:920–930. © 2017 SETAC
Systematic review and meta‐analysis of the performance of second‐trimester screening for prenatal detection of congenital heart defects
Authors: van Velzen Christine L. , Ket Johannes C.F. , van de Ven Peter M. , Blom Nico A. , Haak Monique C. 
Published: November 2017

AbstractBackgroundThe prenatal detection rate of congenital heart defects (CHDs) is increasing, but reported rates vary.ObjectivesTo determine the performance of the second‐trimester anomaly scan to detect CHD.Search strategyPubMed and Embase were searched for relevant studies in any language from inception to February 3, 2017. The search terms included “prenatal diagnosis” or “pregnancy,” “cardiovascular diseases” or “cardiac defects,” “congenital,” and “specificity,” or “sensitivity,” or “cohort study.”Selection criteriaCohort studies assessing the detection rate of CHD during population‐based prenatal screening from 1995 were eligible for inclusion.Data collection and analysisData were collected from identified studies; authors were approached for additional data when necessary. A review and meta‐analysis were performed. When possible, separate analyses were undertaken for isolated CHD cases.Main resultsMeta‐analysis of seven studies showed the pooled detection rate of CHD in unselected populations as 45.1% (95% confidence interval 33.5%–57.0%). However, the rate of detection of univentricular defects and heterotaxy was above 85%. Similar rates were found among cases of isolated CHD.ConclusionsPrenatal detection showed a strong correlation with CHD severity. The detection of conotruncal anomalies needs to improve. A thoroughly organized screening program will be essential to achieve a higher detection rate.
Post‐Ebola situational assessment of opportunities for capacity building at the national obstetrics and gynecology referral hospital in Sierra Leone
Authors: Chan Seay Rachel , Koroma Alimamy P. , Coleman Jenell , Sampson John , Koroma Lucy , Ugwa Emmanuel A. , Anderson Jean 
Published: November 2017

AbstractObjectiveTo describe a site assessment of the Princess Christian Maternity Hospital (PCMH; Freetown, Sierra Leone), the national referral center for reproductive, maternal, newborn, child and adolescent health (RMNCAH) services and logical site for focused efforts to train and expand the RMNCAH workforce in Sierra Leone.MethodsIn April 2016, a mixed‐methods assessment approach was used involving facility observation and staff interviews using the WHO's Service Availability and Readiness Assessment (SARA) tool. Quantitative and qualitative data were obtained.ResultsPCMH had 150 inpatient beds and provided care for more than 4600 deliveries in 2015. The number of maternal deaths increased at a rate of approximately 40% per month from January 2015 to June 2016 (P=0.005). Key factors requiring attention were identified in the categories of infrastructure and supplies, RMNCAH services, and human resources.ConclusionSARA provided a framework for identifying strengths and weaknesses in infrastructure and supplies, RMNCAH services, and human resources. The process described might serve as a model for evaluating obstetrics and gynecology training facilities in low‐ and middle‐income countries. Human resources are currently insufficient for the volume and complexity of patients at PCMH. Numerous opportunities exist for strengthening healthcare services and capacity building in Sierra Leone.
Hydrogel/fiber conductive scaffold for bone tissue engineering
Authors: Khorshidi Sajedeh , Karkhaneh Akbar 
Published: November 2017

AbstractHydrogel/fiber composites have emerged as compelling scaffolds for regeneration purposes. Any biorelated modification or feature may endow more regenerative functionality to these composites. In the present study, a hydrogel/fiber scaffold possessing electrical conductivity in both phases, hydrogel and fiber, has been prepared and evaluated. Fiber component possessed electrical conductivity due to the presence of polyaniline (PANi) and hydrogel fraction thanks to the presence of graphene nanoparticles. PANi based fibers were processed through electrospinning and transformed into a three‐dimensional structure through ultrasonication. The hydrogel precursor solution composed of oxidized polysaccharides, gelatin and graphene with predesigned ratio was added to fibers and left to gel. The results of assessments on pristine hydrogel and hydrogel/fiber denoted that inclusion of conducting fibers into hydrogel increased elastic modulus, roughness and electrical conductivity, whereas decreased hydrophilicity. Moreover, the results showed that hydrogel/fiber composite better supported human osteoblast‐like cell adhesion, proliferation, and morphology comparing hydrogel alone. In a nutshell, the presence of gel/fiber architecture along with electrical conductivity may lead the scaffold to be very promising for bone regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 718–724, 2018.
Atomic force microscopy and nanoindentation investigation of polydimethylsiloxane elastomeric substrate compliancy for various sputtered thin film morphologies
Authors: Maji Debashis , Das Soumen 
Published: November 2017

AbstractCrack free electrically continuous metal thin films over soft elastomeric substrates play an integral part in realization of modern day flexible bioelectronics and biosensors. Under nonoptimized deposition conditions, delamination, and/or cracking of the top film as well as the underlying soft substrate hinders optimal performance of these devices. Hence it is very important to understand and control not only the various deposition factors like power, time, or deposition pressure but also investigate the various interfacial physics playing a critical role in assuring thin film adhesion and substrate compliancy. In the present study, various nanomechanical information of the underlying substrate, namely, crack profile, average roughness, Young's modulus, and adhesion force were studied for uncracked and cracked polydimethylsiloxane (PDMS) surfaces along with pristine and conventional plasma treated PDMS samples as control. Quantification of the above parameters were done using three‐dimensional surface profiler, scanning electron microscopy, nanoindentation, and atomic force microscopy techniques to elucidate the modulus range, average roughness, and adhesion force. Comparative analysis with control revealed remarkable similarity between increased modulus values, increased surface roughness, and reduced adhesion force accounting for reduced substrate compliancy and resulting in film cracking or buckling which are critical for development of various bioflexible devices. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 725–737, 2018.
Absorbable mineral nanocomposite for biomedical applications: Influence of homogenous fiber dispersity on mechanical properties
Authors: Mulky Elias , Maniura‐Weber Katharina , Frenz Martin , Fortunato Giuseppino , Luginbuehl Reto 
Published: November 2017

AbstractElectrospun micro‐ and nanosized fibers are frequently used as reinforcing elements in low temperature ceramic composites for biomedical applications. Electrospinning of fibers yield, however, not individual fibers, but rather fiber‐mats that are difficult to separate. Most investigations have been performed on diced mats and highly nonhomogenous composites. We examined the influence of dispersed electrospun single micro‐ and nanometer fibers on the mechanical properties of calcium phosphate cement composites. Absorbable poly‐l‐lactic‐acid was electrospun yielding fibers with diameters of 244 ± 78 nm, named nanofibers (NF), and 1.0 ± 0.3 μm, named microfibers (MF). These fibers were cut using a particle assisted ultrasonication process and dispersed with hydroxyapatite nanoparticles and composites of low (5%) and high (30%) NF/MF content were engineered. The homogeneity of the fiber distribution was investigated by analyzing fracture areas regarding the number of fibers and Voronoi area size distribution. Variation of fiber distribution was significantly lower in the NF group as compared to the MF group. For composites containing 5% NF (V/V), an eightfold increase in the compressive fracture strength, and for the 30% NF (V/V) a threefold increase compared was measured. The composite containing 5% NF was identified as optimal regarding fiber distribution and strength. Our new method of engineering these composites allows for high volume fractions of NF with low variation in fiber distribution to be incorporated into composites, and shows the importance of using single filaments as reinforcing agents. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 850–857, 2018.
Nitric oxide enhances selenium concentration by promoting selenite uptake by rice roots
Authors: Xiao Qiang , Li Xiu-Ling , Gao Gui-Feng , Chen Juan , Liu Xiang , Shen Zhi-Jun , Zhu Xue-Yi , Zheng Hai-Lei 
Published: November 2017

AbstractNitric oxide (NO) plays a key role in regulating a wide range of physiological and biochemical processes. This study investigated possible effects of NO, which was supplied by sodium nitroprusside (SNP), NO donor, on selenium (Se) concentration, Se species within roots, activities and gene transcription of selenite uptake, and metabolism‐related transporters or enzymes using ICP‐MS, HPLC‐ICP/MS, qRT‐PCR, fluorescence imaging, and biochemical analysis in the roots of rice (Oryza sativa L.) seedling. A suitable SNP concentration (10 µM) increased Se concentration in rice roots. NO enhanced the gene transcription of phosphate transporter OsPT2 and sulfate transporters OsSultr1;2 and OsSultr4;1 that contribute to selenite uptake. Furthermore, NO increased selenocysteine and methyl‐selenocysteine concentrations in roots, stimulated glutathione biosynthesis by up‐regulating the transcript levels of γ‐glutamylcysteine synthetase (γ‐ECS) and glutathione synthetase (GS), and increased cysteine synthase (CS) activity. In conclusion, our results indicate that NO promotes Se concentration of rice seedling roots by enhancing selenite uptake, up‐regulating gene transcription of selenite uptake‐related transporters, and increasing Se metabolism through regulating glutathione biosynthesis.
A case of quetiapine‐induced catatonia
Authors: Lucas Grace L. , Adewumi Adeleke D. 
Published: November 2017

AbstractAimTo present a case of catatonia on exposure to quetiapine.Clinical detailsWe report the case of a 68‐year‐old man with bipolar affective disorder who experienced catatonia upon initiation of quetiapine on day 4 of his admission to hospital. He was commenced on quetiapine 50 mg at night which was increased to 100 mg the following night. He did not have a prior history of any reaction to the medication.Outcome symptomsResolved upon discontinuation of quetiapine.ConclusionThe importance of pharmacovigilance cannot be overemphasised. Clinicians need to be aware that catatonia may occur with the use of quetiapine and patients need to be closely monitored for unexpected reactions.
Online Detection of Functional Groups in SEC via Quantum Cascade Laser IR Spectroscopy
Authors: Morlock Sascha , Kübel Jennifer M. , Beskers Timo F. , Lendl Bernhard , Wilhelm Manfred 
Published: November 2017

AbstractThe development of coupled techniques based on chemically sensitive detectors, such as FTIR or NMR spectrometers, for size exclusion chromatography (SEC) provides sophisticated methods for determining the molecular‐weight‐dependent chemical composition in polymers. However, the detection of rare functionalities such as end groups or branching points presents a challenge, especially for online coupled SEC detection, which is based on low‐concentration chromatography. To address this issue, for the first time, an external cavity quantum cascade laser (EC‐QCL) infrared spectrometer is coupled to an SEC. The system is evaluated using polystyrene/poly(methyl methacrylate) (PS/PMMA) blends. The current limit of detection for the carbonyl (PMMA) stretch vibration at 1730 cm−1 with this technique is 3.5 µg PMMA on a semipreparative column (typical load of 2.5 mg polymer in total). That equals 0.15 mol% of PMMA in the PS/PMMA blend and corresponds to one carbonyl group per 70 kg mol−1 polymer.