bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Moisture and Heat Transport in a Wet Porous Sand Layer with Water Sucking Ability
Authors: Chen Wei , Ling Juanjuan 
Published: August 2016

AbstractThe moisture content and heat transfer in a wet porous sand layer was influenced by the weather conditions while the layer was exposed outdoors. The changes in water content and temperature in the wet porous bed with water supplied due to the weather conditions differed from the case without water supplied via the bottom in the tests. A one‐dimensional mathematical model describing the heat and mass transfer in the unsaturated porous layer was used to analyze the change of the water content, temperature and rate of water evaporation or vapor condensation in the wet porous layer. As the ambient temperature, relative humidity and solar irradiation changed periodically and the gravity and capillary affected the water transport greatly in the wet porous media, variations of water content and temperature occurred cyclically in the wet porous layer that was exposed to outdoor conditions. In the wet porous bed, the rate of the water evaporation or vapor condensation was closely related to the temperature, gradient of the temperature along the depth and the rate of temperature variation over time. The particle size and porosity associated with the permeability had great impact on the water content and its variation range in the wet porous media with water sucking ability while the weather conditions changed periodically. The simulations of the water content and temperature variation in the sand bed agreed with the test data. All these results can be used to analyze the behavior of heat and moisture in the unsaturated porous layer under weather conditions.
Numerical Simulation of Natural Convection in a Triangle Cavity Filled with Nanofluids Using Tiwari and Das' Model: Effects of Heat Flux
Authors: Wang Xiaofeng , Wang Juntao 
Published: August 2016

AbstractIn this article, we present a fully higher‐order compact (FHOC) finite difference method to investigate the effects of heat flux on natural convection of nanofluids in a right‐angle triangle cavity, where the left vertical side is heated with constant heat flux both partially and throughout the entire wall, the inclined wall is cooled, and the rest of walls are kept adiabatic. The Darcy flow and the Tiwari and Das’ nanofluid models are considered. Investigations with four types of nanofluids were made for different values of Rayleigh numbers with the range of 100 ≤ Ra ≤ 50,000, size of heat flux as 0.1 ≤ ε ≤ 1.0, enclosure aspect ratio as 0.5 ≤ AR ≤ 2.0, and solid volume fraction parameter of nanofluids with the range of 0% ≤ ϕ ≤ 20%. Results show that the average heat transfer rate increases significantly as particle volume fraction and Rayleigh numbers increase, and the maximum value of average Nusselt number is obtained by decreasing the enclosure aspect ratio. The results also show that the average heat transfer decreases with an increase in the length of the heater. Furthermore, multiple correlations in terms of the Rayleigh numbers and the solid volume fraction of four types of nanoparticles have been established in a general form.
Does sugar inhibition explain mixing effects in enzymatic hydrolysis of lignocellulose?
Authors: Kadić Adnan , Lidén Gunnar 
Published: August 2016

AbstractBACKGROUNDEnzymatic hydrolysis of lignocellulose is associated with mixing issues, which are likely to affect process performance. The aim of this study was to investigate how viscosity and sugar inhibition influence the mixing‐dependence in hydrolysis of steam‐pretreated spruce.RESULTSThe effect of agitation on low‐viscosity, low‐solid hydrolysis (5% water insoluble solid (WIS)) was marginal, as the conversion after 72 h decreased by 9% when decreasing the agitation rate from 600 to 100 rpm. However, when the viscosity at 5% WIS was increased by Xanthan addition, the effect of agitation was greater, and conversion decreased by 21% when decreasing agitation from 600 to 100 rpm. For high‐viscosity, high‐solid hydrolysis (16% WIS), the conversion decreased by 54% when decreasing the agitation from 600 to 100 rpm. However, when the product concentration was kept low by simultaneous saccharification and fermentation (SSF), the effect of agitation was weaker, and conversion decreased by only 14%.CONCLUSIONThe results of this study strongly suggest that poor mixing in viscous lignocellulose hydrolysis causes local product accumulation, leading to increased inhibition and decreased hydrolysis rates. Decreasing the glucose and cellobiose concentration removes the mixing‐dependence, highlighting SSF as an attractive option for large‐scale hydrolysis and fermentation of steam‐pretreated softwood. © 2016 Society of Chemical Industry
Evaluation of intravoxel incoherent motion fitting methods in low‐perfused tissue
Authors: Meeus Emma M. , Novak Jan , Withey Stephanie B. , Zarinabad Niloufar , Dehghani Hamid , Peet Andrew C. 
Published: August 2016

PurposeTo investigate the robustness of constrained and simultaneous intravoxel incoherent motion (IVIM) fitting methods and the estimated IVIM parameters (D, D* and f) for applications in brain and low‐perfused tissues.Materials and MethodsModel data simulations relevant to brain and low‐perfused tumor tissues were computed to assess the accuracy, relative bias, and reproducibility (CV%) of the fitting methods in estimating the IVIM parameters. The simulations were performed at a series of signal‐to‐noise ratio (SNR) levels to assess the influence of noise on the fitting.ResultsThe estimated IVIM parameters from model simulations were found significantly different (P < 0.05) using simultaneous and constrained fitting methods at low SNR. Higher accuracy and reproducibility were achieved with the constrained fitting method. Using this method, the mean error (%) for the estimated IVIM parameters at a clinically relevant SNR = 40 were D 0.35, D* 41.0 and f 4.55 for the tumor model and D 1.87, D* 2.48, and f 7.49 for the gray matter model. The most robust parameters were the IVIM‐D and IVIM‐f. The IVIM‐D* was increasingly overestimated at low perfusion.ConclusionA constrained IVIM fitting method provides more accurate and reproducible IVIM parameters in low‐perfused tissue compared with simultaneous fitting.Level of Evidence: 3J. MAGN. RESON. IMAGING 2017;45:1325–1334
Influence of regional iron on the motor impairments of Parkinson's disease: A quantitative susceptibility mapping study
Authors: Guan Xiaojun , Xuan Min , Gu Quanquan , Xu Xiaojun , Huang Peiyu , Wang Nian , Shen Zhujing , Xu Jingjing , Luo Wei , Zhang Minming 
Published: August 2016

PurposeBecause the roles of striatal‐thalamo‐cortical and cerebello‐thalamo‐cortical circuits in the heterogeneous motor impairments of Parkinson's disease (PD) are becoming recognized, this study was designed to investigate the relationships between regional iron in the cardinal subcortical nuclei in these circuits and the different motor impairments.Materials and MethodsSixty‐two PD patients and 40 normal subjects were included and accepted for Enhanced T2‐Star Weighted Angiography Scanning (3.0T). According to the Unified Parkinson's Disease Rating Scale, patients were divided into tremor‐dominant (PD‐TD) and akinetic/rigid‐dominant groups (PD‐AR). The intergroup differences of magnetic susceptibility in those cardinal nuclei were measured. Correlation analyses between magnetic susceptibility and motor impairments were performed in all patients.ResultsNigral magnetic susceptibility significantly increased for each PD group compared with controls (P < 0.001 for PD‐TD; P = 0.001 for PD‐AR). Magnetic susceptibility in the dentate nucleus (DN) and red nucleus (RN) for the PD‐TD patients were significantly increased compared with controls (P < 0.001 and P = 0.004, respectively). Magnetic susceptibility in these regions was also significantly correlated with tremor severity (r = 0.444, P = 0.001 for DN; r = 0.418, P = 0.001 for RN). Significant correlation between caudate magnetic susceptibility and akinetic/rigid severity were observed (r = –0.322, P = 0.015).ConclusionThis study provides evidence that nigral iron accumulation is a common characteristic in PD, while iron accumulation in the DN and RN is correlated with tremor symptoms. Our data also indicate that caudate iron content may be a potential marker for akinetic/rigid progression.Level of Evidence: 3J. MAGN. RESON. IMAGING 2017;45:1335–1342
Ilex paraguariensis crude extract acts on protection and reversion from damage induced by t‐butyl hydroperoxide in human erythrocytes: a comparative study with isolated caffeic and/or chlorogenic acids
Authors: Portela José Luiz , Soares Deividi , Rosa Hemerson , Roos Daniel Henrique , Pinton Simone , Ávila Daiana Silva , Puntel Robson L 
Published: August 2016

AbstractBACKGROUNDStudies comparing the effects of phytochemicals under different regimens of exposure are necessary to give a better indication about their mechanism(s) of protection. Hence, in the present study, we investigated the preventive (pre‐incubation), protective (co‐incubation) and/or remediative (post‐incubation) activity of chlorogenic acid and caffeic acids, in comparison with Ilex paraguariensis crude extract, against t‐butyl hydroperoxide (t‐BHP)‐induced damage to human erythrocytes.RESULTSWe found that both caffeic and chlorogenic acids were able to prevent and revert the hemolysis associated with t‐BHP exposure. By contrast, isolated compounds (alone or in combination) presented no effect on basal and/or t‐BHP‐induced non‐protein thiol (NPSH) oxidation or production of thiobarbituric acid reactive substances (TBBARS). In turn, I. paraguariensis extract was effective to prevent, protect and revert the hemolysis associated with t‐BHP exposure. Moreover, I. paraguariensis significantly protects and reverts t‐BHP‐induced NPSH oxidation and TBARS production.CONCLUSIONSWe have found that I. paraguariensis extract acts better with respect to the protection and reversion of t‐BHP‐associated changes, whereas isolated compounds are more active in preventing and reverting t‐BHP pro‐hemolytic action. Moreover, our data suggest that the pro‐hemolytic activity of t‐BHP may occur via mechanism(s) other(s) than lipid peroxidation and/or NPSH oxidation. © 2016 Society of Chemical Industry
Einflußeiner Verzinkung auf die Korrosion von mit Zementmörtel beschichtetem Stahl in NaCl‐Lösung
Authors: Hildebrand Heinrich , Schwenk W. 
Published: August 2016

AbstractVerzinkte oder gebeizte Blechproben wurden mit Portlandzement‐Mörtel unterschiedlicher Erhärtung und Wasserzementwerte beschichtet und 1 bis 5 Jahre in 0,5 M NaCl vollständig oder zur Hälfte eingetaucht. In Abhängigkeit von der Versuchsdauer wurden die Freien Korrosionspotentiale und elektrische Widerstände gemessen.Den größten Einfluß auf die Korrosionsbeständigkeit der Bleche haben die Verzinkung und die Tauchart.Vollständig eingetauchte Proben zeigen sehr negative Potentiale. Sie können deshalb als Kathoden in Korrosionselementen nicht wirksam werden. Die Bleche korrodieren im Mörtel nahezu nicht. Zur Hälfte eingetauchte Proben zeigen verhältnismäßig positive Potentiale. Auch bei verzinkten Proben wird das Potential im Laufe der Zeit zu gleich positiven Potentialen verschoben. Solche Proben kommen somit als Kathoden für Korrosionselemente infrage. An der Wasser/Luft‐Grenze entsteht örtliche Korrosion. Bei unverzinkten Proben kann die Mörtelschicht durch Korrosionsprodukte aufbrechen. Bei verzinkten Proben kann die örtliche Korrosion wesentlich verzögert werden.Im Detail werden die Ergebnisse zur Klärung praktischer Probleme der Elementbildung, des inneren und äußeren Rohrschutzes und des Bewertungsstahls bei Stahl‐Wasser‐Bauten erörtert.
Untersuchungen zur Werkstoffschädigung im Hochtemperatur‐LCF‐Bereich
Authors: Lachmann E. 
Published: August 2016

AbstractDas Werkstoffverhalten unter Hochtemperatur‐LCF‐Beanspruchung wird überwiegend von den zeitabhängigen Schädigungsprozessen Kriechen und Oxidation (Umgebungseinfluß) bestimmt. Zur Untersuchung der Einflußgrößen Dehngeschwindigkeit, Zyklusform und Umgebung auf die Werkstoffschädigung wurden dehnungsgesteuerte Zug‐Druck‐Wechselversuche an Proben aus 13 CrMo 44 und X 10 CrNiTi 18 9 bei 560°C bzw. 530°C durchgeführt.Anhand umfangreicher metallographischer und mikrofraktographischer Untersuchungen wird die Wechselwirkung von zyklischer Wechselverformung (Ermüdung), Umgebung (Oxidation) und Kriechen (Relaxation) auf die Werkstoffschädigung dargestellt. Es wird weiterhin gezeigt, daß die für das Ermüdungsverhalten hauptsächlich verantwortliche Einflußgröße von den Parametern Werkstoff, Beanspruchungshöhe, Dehngeschwindigkeit und Zyklusform abhängt.
On the atmospheric corrosion of thin copper films
Authors: v. d. Leest R. E. 
Published: August 2016

AbstractSputtered and electrodeposited copper specimens were exposed to the laboratory atmosphere for 18 months, after which the corrosion products were analysed by electrochemical methods and reflectance spectra. The formation of corrosion products takes place in three stages: initially cuprous oxide is formed, followed by the growth of cuprous sulphide, and finally cuprous oxide is converted to cuprous sulphide. The presence of water is essential for these corrosion reactions to occur.
Korrosionselektrochemisches Verhalten von Eisen‐Nickel‐Legierungen in sauren Sulfidlösungen
Authors: Raicheff R. , Aroyo M. , Arpadjan S. 
Published: August 2016

AbstractMit Hilfe der Methode des Polarisationswiderstandes und der potentiodynamischen Polarisationsmessungen wurde der Einfluß des Schwefelwasserstoffs auf das korrosionselektrochemische Verhalten der Eisen‐Nickel‐Legierungen in schwefelsauren Medien untersucht. Es wurde festgestellt, daß das H2S stimulierend auf die Korrosionsgeschwindigkeit wirkt. Diese Wirkung hängt vom pH‐Wert der Lösung, von der Zusammensetzung und der Struktur der Legierungen ab und ist für Legierungen mit erhöhtem Nickelgehalt stärker ausgeprägt. Es wurde gezeigt, daß die Anwesenheit des H2S in der Lösung sowohl auf die anodische Reaktion der Metallauflösung, als auch auf die kathodische Reaktion der Wasserstoffabspaltung wirkt. Die Unterschiede im elektrochemischen Verhalten der beiden Fe‐Ni‐Legierungen (mit einer Struktur der α‐ und γ‐Phase) zeigen sich in Gegenwart von H2S nur bei der kathodischen Reaktion. Mittels Atomabsorptionsanalyse wurde festgestellt, daß die Anwesenheit des H2S in schwefelsauren Medien keine selektive Auflösung der Komponenten der Fe‐Ni‐Legierungen verursacht.
Reaktionen zwischen Natriumpolysulfid und Stromabnehmermaterialien für Natrium/Schwefel‐Batterien
Authors: Heusler K. E. , Grzegorzewski A. 
Published: August 2016

AbstractZur Messung der Korrosionsgeschwindigkeit von Materialien, die als Stromabnehmer in der Natriumpolysulfidschmelze von Natrium/Schwefel‐Batterien interessant sind, wurden die zeitlichen Veränderungen der Dicke dünner Schichten in situ mit einer 4‐Punkt‐Widerstandsmethode verfolgt. Die stationäre Korrosionsgeschwindigkeit des Aluminiums am Ruhepotential war in Na2S4 bei 350°C ⩽ 150 μm/a, die Aktivierungsenthalpie 300 kJ/mol. Die Korrosionsgeschwindigkeit wuchs mit dem Quadrat des kathodischen Gesamtstroms an. Anodische Polarisation erhöhte die Dicke der passivierenden Deckschicht, kaum die mittlere Korrosionsgeschwindigkeit, und führte zu lokal unterschiedlichen Geschwindigkeiten.Auf dem Stahl X10CrA124 (W.Nr. 1.4762) wuchs eine Deckschicht nach dem parabolischen Zeitgesetz, bis eine stationäre Korrosionsgeschwindigkeit, bei 350°C etwa 90 μm/a, erreicht war. Der aluminiumfreie Stahl X10CrNiMoTi 18 10 (W.Nr. 1.4571) korrodierte mit der Geschwindigkeit von 1,5 mm/a. Die Korrosionsgeschwindigkeit, bei 350°C etwa 90 μm/a, ereicht war. Der aluminiumfreie Stahl X10CrNiMoTi 18 10 (W.Nr. 1.4571) korrodierte mit der Geschwindigkeit von 1,5 mm/a. Die Korrosionsgeschwindigkeit des Chroms war noch höher. Dagegen korrodierten Stellite 6 und Glanzkohlenstoff mit Geschwindigkeiten < 2 μm/a.
The corrosion behavior of stainless steels and copper alloys exposed to natural seawater
Authors: Little Brenda J. , Mansfeld Florian B. 
Published: August 2016

AbstractThe corrosion behavior of stainless steels, titanium and copper alloys exposed to flowing Pacific Ocean water was characterized using surface analytical and electrochemical techniques. Biofilm formation on stainless steels and titanium resulted in thin films of bacteria and diatoms that did not cause significant changes of the corrosion potential (Ecorr) or surface properties. Rotating cylinder experiments indicated that both Ecorr and corrosion rates for stainless steels and titanium were independent of mass transport. Four surface layers were identified on copper‐containing materials: substratum metal; an inorganic chloride corrosion layer that contained alloying elements; a biofilm; and crystalline, spherical phosphate‐rich deposits. All copper surfaces were colonized by bacteria independent of alloy composition. The complexity of the impedance spectra for copper‐containing materials was attributed to formation of surface layers and contributions of charge transfer and mass transport controlled reactions mediated by the layers. Both anodic and cathodic reactions for copper‐based materials were affected by mass transport.
Corrosion of synthetic metals
Authors: Beck Fritz , Michaelis Ronald 
Published: August 2016

AbstractIntrinsically conducting polymers as polypyrrole or polythiophene are new materials which have found widespread interest in the last ten years. Acceptor type doping leads to a solid, which is well comparable to graphite salts. For any kind of practical application of these polymers, the problem of adequate long term stability under environmental conditions must be solved. There are only a few measurements of conductivity vs. time in the air to derive conclusions in this direction, e.g. for polypyrrole. For the first time we present results of a systematic research into the understanding of corrosion phenomena, which occur in aqueous eletrolytes at different pH. Polypyrrole is selected as a well established candidate for a synthetic metal. Layers at a nominal thickness of 10μm on platinum, doped with BF4− anions, were investigated in aqueous buffers in the pH‐range of 1–13. Corrosion was determined via the measurement of the residual redox capacities. The material corroded after a rapid electrochemical mechanism and a relatively slow chemical mechanism. Both processes involve the radical cationic centers (polarons) in the solid. The time constants varied from 102 to > 108 s. Our findings allow for a better understanding of corrosion and selfdischarge of polypyrrole. Other conducting polymers were found to corrode after the same mechanism.
Influence of surface treatment on the photoelectrochemical behaviour of Y‐Ba‐Cu‐O thin films
Authors: Hampel M. , Grabner E. W. , Jabs T. , Strehblow H.‐H. 
Published: August 2016

AbstractY‐Ba‐Cu‐O films with different surface treatments have been studied by photoelectrochemical and XPS measurements. The influence of etching by bromine in ethanol of these films has been followed by means of the electrochemical oxidation of ferrocene in an aprotic electrolyte. From the dependence of dark and photocurrent on etching time it is concluded that Y‐Ba‐Cu‐O thin films on LaAlO3 are covered by a 1, 1nm thick nonstoichiometric surface layer. The cathodic polarization of Y‐Ba‐Cu‐O at ‐0,9 V vs. Ag/AgCl in acetonitrile/0,1 M lithium perchlorate leads to the formation of a lithium‐containing, oxygen‐enriched surface layer. The photoelectrochemical response of the reduced films is similar to that of cuprous oxide and passive layers on copper.
Microfluidic Studies of Polymer Adsorption in Flow
Authors: Salari Alinaghi , Kumacheva Eugenia 
Published: August 2016

Adsorption of polymer molecules under flow conditions governs a broad range of desired or undesired phenomena and has a broad range of applications. Microfluidic platforms integrated with analytical instrumentation offer the capability to study polymer adsorption in flow in a time‐ and labour‐efficient manner. Precise control of the microchannel dimensions and flow parameters enables accurate control of shear forces imposed on polymer solutions and on the molecules deposited on the surface, along with high sensitivity, enhanced reliability, and low reagent consumption. This review highlights recent advances in theoretical and experimental microfluidic studies of polymer immobilization under flow conditions in three area, namely, biosensing, biofouling, and studies of thrombosis and hemostasis.
image
Light‐Induced Bulk Architecturation of PDMS Membranes
Authors: Stricher Arthur , Rinaldi Renaud G. , Machado Guilherme , Chagnon Gregory , Favier Denis , Chazeau Laurent , Ganachaud François 
Published: August 2016

One major challenge of biomaterial engineering is to mimic the mechanical properties of anisotropic, multifunctional natural soft tissues. Existing solutions toward controlled anisotropy include the use of oriented reinforcing fillers, with complicated interface issues, or UV‐curing processing through patterned masks, that makes use of harmful photosensitive molecules. Here, a versatile process to manufacture biocompatible silicone elastomer membranes by light degradation of the platinum catalyst prior to thermal cross‐linking is presented. The spatial control of network density is demonstrated by experimental and theoretical characterizations of the mechanical responses of patterned cross‐linked membranes, with a view to mimic advanced implantable materials.
image
Reversible Deactivation Radical Polymerization of Monomers Containing Activated Aziridine Groups
Authors: McLeod David C. , Tsarevsky Nicolay V. 
Published: August 2016

Polymers bearing activated aziridine groups are attractive precursors to α‐substituted‐β‐amino‐functionalized materials due to the enhanced reactivity of the pendant aziridine functionalities toward ring‐opening by nucleophiles. Two aziridine‐containing styrenic monomers, 2‐(4‐vinylphenyl)aziridine (VPA) and N‐mesyl‐2‐(4‐vinylphenyl)aziridine (NMVPA), were polymerized under a variety of reversible deactivation radical polymerization conditions. Low‐catalyst‐concentration atom transfer radical polymerization (LCC‐ATRP) and reversible addition‐fragmentation chain‐transfer (RAFT) polymerization were ineffective at producing well‐defined polymers from VPA due to side reactions between the aziridine functionalities and the agents controlling the polymerizations (catalysts or chain transfer agents). PolyVPA produced under nitroxide‐mediated polymerization (NMP) conditions had narrow molecular weight distribution at low to moderate conversions of monomer, but branched and eventually cross‐linked polymers were formed at higher conversions due to ring‐opening reactions of the aziridine groups. Most of these undesirable side reactions were eliminated by attaching a methanesulfonyl (mesyl) group to the aziridine nitrogen atom, and well‐defined linear homopolymers with targeted molecular weights were realized from NMVPA under RAFT and NMP conditions; however, side reactions between the aziridine groups and the catalyst in LCC‐ATRP still occured and the polymerization was uncontrolled using this technique.
image