bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Elektronentunnelraten im Atmungskettenkomplex I sind auf eine effiziente Energiewandlung abgestimmt
Authors: de Vries Simon , Dörner Katerina , Strampraad Marc J. F. , Friedrich Thorsten 
Published: January 2015

AbstractDer Atmungskettenkomplex I wandelt die freie Energie, die bei der Reduktion von Ubichinon durch NADH frei wird, in einen Protonengradienten über die Membran um. Die biologische Redoxreaktion wird von einem Flavinmononukleotid und einer Kette von sieben Eisen‐Schwefel‐Zentren katalysiert. Die Elektronentransfergeschwindigkeiten zwischen den Zentren wurden über eine schnelle “Freeze‐Quench”‐Methode und Analyse der Proben mittels EPR‐ und UV/Vis‐Spektroskopie bestimmt. Der Komplex I oxidiert sehr schnell drei Moleküle NADH; dabei hängt die Elektronentunnelrate zwischen den beiden Zentren der Kette mit dem größten Abstand zueinander vom Redoxzustand des distalen Zentrums N2 ab. Diese Geschwindigkeit ist sechsmal geringer, wenn N2 im reduzierten Zustand vorliegt. Die konformativen Änderungen, die mit der Reduktion des Zentrums N2 einhergehen, verlangsamen die elektronische Kopplung des längsten Transferschritts. Die Kette der Eisen‐Schwefel‐Zentren ist somit nicht einfach ein Draht für den Elektronentransfer, sondern sie passt die Elektronentunnelraten der Zeitskala der konformativen Bewegungen an, die für die Protonentranslokation benötigt werden. Die Synchronisierung von Geschwindigkeiten ist ein generelles Prinzip, um die Spezifität enzymatischer Reaktionen zu erhöhen.
Synergistic Interplay of a Non‐Heme Iron Catalyst and Amino Acid Coligands in H2O2 Activation for Asymmetric Epoxidation of α‐Alkyl‐Substituted Styrenes
Authors: Cussó Olaf , Ribas Xavi , Lloret‐Fillol Julio , Costas Miquel 
Published: January 2015

AbstractHighly enantioselective epoxidation of α‐substituted styrenes with aqueous H2O2 is described by using a chiral iron complex as the catalyst and N‐protected amino acids (AAs) as coligands. The amino acids synergistically cooperate with the iron center in promoting an efficient activation of H2O2 to catalyze epoxidation of this challenging class of substrates with good yields and stereoselectivities (up to 97 % ee) in short reaction times.
Induction of a Proton Gradient across a Gold‐Supported Biomimetic Membrane by Electroenzymatic H2 Oxidation
Authors: Gutiérrez‐Sanz Óscar , Tapia Cristina , Marques Marta C. , Zacarias Sonia , Vélez Marisela , Pereira Inês A. C. , De Lacey Antonio L. 
Published: January 2015

AbstractEnergy‐transduction mechanisms in living organisms, such as photosynthesis and respiration, store light and chemical energy in the form of an electrochemical gradient created across a lipid bilayer. Herein we show that the proton concentration at an electrode/phospholipid‐bilayer interface can be controlled and monitored electrochemically by immobilizing a membrane‐bound hydrogenase. Thus, the energy derived from the electroenzymatic oxidation of H2 can be used to generate a proton gradient across the supported biomimetic membrane.
Pd‐Nanoparticle‐Supported, PDDA‐Functionalized Graphene as a Promising Catalyst for Alcohol Oxidation
Authors: Bin Duan , Ren Fangfang , Wang Ying , Zhai Chunyang , Wang Caiqin , Guo Jun , Yang Ping , Du Yukou 
Published: January 2015

AbstractPoly(diallyldimethylammonium chloride) (PDDA) has been employed as a modifying material for the development of new functional materials; then, the functionalized graphene was employed as a support for Pd nanoparticles through a facile method. The structures and morphologies of the as‐synthesized Pd/PDDA–graphene composites were extensively characterized by Raman spectroscopy, XRD, XPS, and TEM. Morphological observation showed that Pd NPs with average diameters of 4.4 nm were evenly deposited over the functionalized graphene sheets. Moreover, the electrochemical experiments indicated that the Pd/PDDA–graphene catalyst showed improved electrocatalytic activity toward alcohol‐oxidation reactions compared to the Pd/graphene and commercial Pd/C systems, as well as previously reported Pd‐based catalysts. This study demonstrates the great potential of PDDA‐functionalized graphene as a support for the development of metal–graphene nanocomposites for important applications in fuel cells.
Metal‐immobilized magnetic nanoparticles for cytochrome C purification from rat liver
Authors: Perçin Işık , Karakoç Veyis , Ergün Bahar , Denizli Adil 
Published: January 2015

AbstractCu2+‐immobilized magnetic poly(hydroxyethylmethacrylate‐N‐methacryloyl‐(l)‐histidinemethylester) (mPHEMAH) nanoparticles were prepared by surfactant‐free emulsion polymerization for cytochrome C (cyt C) purification from rat liver. Elemental analysis, atomic force microscopy, zeta sizer, and vibrating sample magnetometer were used to characterize mPHEMAH nanoparticles. In addition to these characterization steps, surface area, average particle size, and size distribution of mPHEMAH nanoparticles were determined. Quantity of immobilized Cu2+ was measured using atomic absorption spectrophotometry. N‐Methacryloyl‐(l)‐histidinemethylester and Cu2+ content of mPHEMAH nanoparticles were 0.18 mmol/g polymer and 0.11 mmol/g polymer, respectively. Specific surface area of Cu2+‐immobilized mPHEMAH nanoparticles was 1180 m2/g. Effect of initial cyt C concentration, pH, temperature, and ionic strength on cyt C adsorption onto Cu2+‐immobilized mPHEMAH nanoparticles was investigated. Maximum cyt C adsorption capacity of Cu2+‐immobilized mPHEMAH nanoparticles was 311.9 mg/g polymer. Maximum adsorption was obtained at pH 8.0 and 4 °C. Cu2+‐immobilized mPHEMAH nanoparticles were used ten times with 4.1% decrease in adsorption capacity. In the last stage, Cu2+‐immobilized mPHEMAH nanoparticles were used to purify cyt C from rat liver tissue, and the purity of desorbed fractions was controlled by SDS‐PAGE.
Successful versus unsuccessful antegrade recanalization of single chronic coronary occlusion: Eight‐year experience and outcomes by a propensity score ascertainment
Authors: Jaguszewski Milosz , Ciecwierz Dariusz , Gilis‐Malinowska Natasza , Fijalkowski Marcin , Targonski Radoslaw , Masiewicz Emilia , Strozyk Aneta , Duda Maciej , Chmielecki Michal , Lewicki Lukasz , Dubaniewicz Witold , Burakowski Slawomir , Drewla Piotr , Skarzynski Pawel , Rynkiewicz Andrzej , Alibegovic Jasmina , Landmesser Ulf , Gruchala Marcin 
Published: January 2015

AimsThe effectiveness of revascularization of chronic total occlusion (CTO) remains intriguing. Thus, we sought to investigate whether a successful PCI for single CTO improves outcomes in a setting of stable angina and chronic occlusion of single coronary artery.Methods and ResultsOf 11 957 consecutive patients referred for nonurgent PCI between 2003 and 2010, 1110 displayed single CTO and were enrolled to the central CTO‐registry database. The primary end‐point included all‐cause mortality, the secondary end‐point a composite of safety outcome measure of all‐cause death, nonfatal‐MI, the need for urgent revascularization and stroke. The major adverse cardiovascular event (MACE) records were extracted from the national administrative database and all patients were linked to the long‐term follow‐up. Since the patient assignment was not random, we performed the propensity scoring to minimize selection bias; 734 patients (66%) had a successful PCI‐CTO. Compared with successful procedures, unsuccessful procedures had similar rates of all‐cause death both in crude (HR, 0.78; 95%CI, 0.49–1.25; P = 0.30) and adjusted analysis (HR, 0.80; 95%CI, 0.50‐1.28; P = 0.34). A similar, significant reduction in overall MACE was noted with successful PCI‐CTO compared with unsuccessful procedure in unadjusted (HR, 0.74; 95%CI, 0.56–0.96; P = 0.020) and adjusted calculation (HR, 0.73; 95%CI, 0.56–0.96; P = 0.019). Patients after successful PCI‐CTO as compared with failed recanalization less frequently underwent surgical revascularization. The benefit was sustained at 3 years follow‐up.ConclusionsSuccessful PCI for single CTO does not improve long‐term survival, nonetheless, is associated with reduced overall MACE and the need for surgical revascularization. © 2015 Wiley Periodicals, Inc.
An Enhanced Anode based on Polymer‐Coated Carbon Black for use as a Direct Methanol Fuel Cell Electrocatalyst
Authors: Yang Zehui , Hafez Inas H. , Berber Mohamed R. , Nakashima Naotoshi 
Published: January 2015

AbstractSluggish methanol oxidation reaction and low durability are the main obstacles for commercialization of direct methanol fuel cells (DMFCs). In this study, we describe the fabrication of 4 different carbon black (CB)‐based electrocatalysts for the DMFC by changing the weight ratio between the Pt feed and polymer wrapped carbon support. In all the fabricated electrocatalysts, CB was coated with poly[2,2′‐(2,6‐pyridine)‐5,5′‐bibenzimidazole] on which the Pt nanoparticles were deposited, which were further coated with poly(vinylphosphonic acid). We found that a decrease in the Pt particle size produced higher catalytic activity. The electrochemical surface area (ECSA) of the electrocatalyst with the smallest Pt particle size was 120.8±12.0 m2 gPt−1. The mass activity of the methanol oxidation reaction reached 1860 mA mgPt−1, which is, to the best of our knowledge, the highest value among the recorded catalytic activities of the CB‐based electrocatalysts. Moreover, after 100 000 cycles the electrocatalyst displayed only 38 % and 10.7 % decrease in ECSA and methanol oxidation activity, respectively. Such an obtained durability was ≈10 times higher than that of the commercial CB/Pt electrocatalyst.
Polyaniline‐Coated Hollow Fe2O3 Nanoellipsoids as an Anode Material for High‐Performance Lithium‐Ion Batteries
Authors: Ma Ruguang , Wang Man , Dam Duc Tai , Yoon Yong‐Jin , Chen Yu , Lee Jong‐Min 
Published: January 2015

AbstractPolyaniline‐coated hollow Fe2O3 nanoellipsoids were successfully synthesized by using a solvothermal method followed by a post‐coating step. The as‐fabricated hollow Fe2O3@PANi nanoellipsoids deliver charge capacities of 366, 223.4, and 105.8 mAh g−1 at 0.5, 1.0, and 2.0 C, respectively, and retain a charge capacity of 412.1 mAh g−1 for 150 cycles at 0.2 C, demonstrating improved rate capability as well as extended cycling lifespan.
Covalent Modification of Graphene Oxide with Carbazole Groups for Laser Protection
Authors: Bai Ting , Li Cong‐Qi , Sun Jie , Song Yi , Wang Jun , Blau Werner J. , Zhang Bin , Chen Yu 
Published: January 2015

AbstractIn the past decades, significant effort has been invested into the research and development of optical limiting materials and processes in order to develop practical solutions for the protection from laser beams. In this study, a new soluble graphene oxide based material (GO–Cz) has been synthesized through the covalent modification of graphene oxide (GO) with a carbazole derivative (Cz). The formation of an amido bond between the Cz group and GO has been confirmed by X‐ray photoelectron and Fourier transform infrared spectroscopy. At the same concentration, both the nonlinear extinction coefficient and the imaginary third‐order susceptibility were increased by a factor of ≈6.93 at 532 nm and ≈6.07 at 1064 nm relative to those of GO, as a result of the covalent grafting of the Cz moieties onto the GO surface. The GO–Cz dispersions exhibit a much better optical limiting performance than GO and GO/Cz blends at both 532 and 1064 nm due to the possible intramolecular electron‐transfer between the GO and Cz moieties and the effective combination of the different nonlinear optical mechanisms.
Mild and Selective Activation and Substitution of Strong Aliphatic CF Bonds
Authors: Janjetovic Mario , Träff Annika M. , Hilmersson Göran 
Published: January 2015

AbstractA procedure for chemoselectively manipulating the strong aliphatic CF bond with direct transformation into a CN bond under mild conditions is reported. The activation and subsequent substitution of primary alkyl fluorides is mediated by La[N(SiMe3)2]3, and results in high to excellent yields of tertiary amines. The methodology displays high selectivity towards the C(sp3)F bond, and a variety of secondary amines are applicable as nucleophiles. Mechanistic investigations reveal a reaction that is first order with respect to [La[N(SiMe3)2]3], [R1R2NH], and [alkyl fluoride], and a 6‐membered cyclic transition state is proposed. In addition, 1H NMR spectroscopy shows that La[N(SiMe3)2]3 is the active species involved in the substitution and that protonolysis of the amine, yielding La[NR1R2]3, lowers the reactivity.
Sonochemical Synthesis of Gold Nanoparticles by Using High Intensity Focused Ultrasound
Authors: Yusof Nor Saadah Mohd , Ashokkumar Muthupandian 
Published: January 2015

AbstractThe sonochemical synthesis of gold nanoparticles (GNPs) with different shapes and size distributions by using high‐intensity focused ultrasound (HIFU) operating at 463 kHz is reported. GNP formation proceeds through the reduction of Au3+ to Au0 by radicals generated by acoustic cavitation. TEM images reveal that GNPs show irregular shapes at 30 W, are primarily icosahedral at 50 W and form a significant amount of nanorods at 70 W. The size of GNPs decreases with increasing acoustic power with a narrower size distribution. Sonochemiluminescence images help in the understanding of the effect of HIFU in controlling the size and shapes of GNPs. The number of radicals that form and the mechanical forces that are generated control the shape and size of the GNPs. UV/Vis spectra and TEM images are used to propose a possible mechanism for the observed effects. The results presented demonstrate, for the first time, that the HIFU system can be used to synthesise size‐ and shape‐controlled metal nanoparticles.
Multichromophoric Organic Molecules Encapsulated in Polymer Nanoparticles for Artificial Light Harvesting
Authors: Bhattacharyya Santanu , Jana Bikash , Patra Amitava 
Published: January 2015

AbstractWe designed a self‐assembled multichromophoric organic molecular arrangement inside polymer nanoparticles for light‐harvesting antenna materials. The self‐assembled molecular arrangement of quaterthiophene molecules was found to be an efficient light‐absorbing antenna material, followed by energy transfer to Nile red (NR) dye molecules, which was confined in polymer nanoparticles. The efficiency of the antenna effect was found to be 3.2 and the effective molar extinction coefficient of acceptor dye molecules was found to be enhanced, which indicates an efficient light‐harvesting system. Based on this energy‐transfer process, tunable photo emission and white light emission has been generated with 14 % quantum yield. Such self‐assembled oligothiophene–NR systems encapsulated in polymer nanoparticles may open up new possibilities for fabrication of artificial light harvesting system.
The Thermodynamic Driving Force for Kinetics in General and Enzyme Kinetics in Particular
Authors: Pekař Miloslav 
Published: January 2015

AbstractThe thermodynamic driving force of a reaction is usually taken as the chemical potential difference between products and reactants. The forward and backward reaction rates are then related to this force. This procedure is of very limited validity, as the resulting expression contains no kinetic factor and gives little information on reaction kinetics. The transformation of the reaction rate as a function of concentration (and temperature) into a function of chemical potential should be more properly performed, as illustrated by a simple example of an enzymatic reaction. The proper thermodynamic driving force is the difference between the exponentials of the totaled chemical potentials of reactants and products.
Unexpected Tackifiers from Isosorbide
Authors: Zenner Michael D. , Madbouly Samy A. , Chen Jason S. , Kessler Michael R. 
Published: January 2015

AbstractMolecularly well‐defined tackifiers with up to 100 % bio‐content were prepared from isosorbide and various cyclic anhydrides. These tackifiers are tacky over a broad temperature range and exhibit high maximum tack (ca. 2000 kPa). Structural modifications shift the temperature at which maximum tack is observed and change the viscosity of the tackifiers.
Physiological response and ion accumulation in two grasses, one legume, and one saltbush under soil water and salinity stress
Authors: Bhuiyan Mohammad , Raman Anantanarayanan , Hodgkins Dennis , Mitchell David , Nicol Helen 
Published: January 2015

AbstractA glasshouse–pot trial using four levels of soil moisture (>100%, 90%, 75%, and 60% field capacity) and three levels of salinity (1.0 dSm–1, 3.5 dSm–1, and 6.0 dSm–1) was done to evaluate Na+, K+, and Cl− accumulation capacity and the physiological responses (net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, quantum efficiency of PSII, and non‐photochemical quenching) in Melilotus siculus, Tecticornia pergranulata, Cynodon dactylon , and Thinopyrum ponticum. Results reveal that the combined effects of soil water and salinity had a significant effect on Na+ and Cl− accumulation and not on that of K+. Concentrations of Na+ and Cl− and non‐photochemical quenching increased significantly whereas, the net photosynthetic rate (Pn), stomatal conductance (gs), and intercellular CO2 concentration decreased significantly in the tested plants, because of salinity. Salinity had no significant effect on the maximum quantum yield and relative water contents in shoots. Soil moisture had a significant effect on Na+, K+, and Cl− accumulation and the physiological responses in tested plants. T. pregranulata accumulated the highest concentrations of Na+ and Cl− and had the lowest Pn. C. dactylon accumulated the lowest concentrations of Na+ and Cl−, whereas Pn was the highest. No strong positive correlation between Pn and gs was evident in tested plants. We indicate that the reduced physiological performance was because of non‐stomatal activities. Na+ and Cl− accumulation capacity in the tested plants was in the following order: T. pergranulata>M. siculus>T. ponticum>C. dactylon. C. dactylon, a C4 plant, accumulated lower salt ions than the other three C3 plants. Copyright © 2015 John Wiley & Sons, Ltd.
Homoleptic and Heteroleptic Bismuth(III) Thiazole–Thiolates and the Influence of Ring Substitution on Their Antibacterial and Antileishmanial Activity
Authors: Luqman Ahmad , Blair Victoria L. , Brammananth Rajini , Crellin Paul K. , Coppel Ross L. , Kedzierski Lukasz , Andrews Philip C. 
Published: January 2015

AbstractTwo new homo‐ and heteroleptic bismuth thiazole‐thiolato complexes derived from 4‐phenylthiazole‐2‐thiol MBT(H) have been synthesised and structurally characterised, [BiPh(MBT)2]2 and [Bi(MBT)3]2. Syntheses were achieved using BiPh3 or Bi(OtBu)3 in protolysis reactions with MBT(H), or by salt metathesis with BiCl3 or BiPhCl2 and the sodium thiolate, [NaMBT]. The complexes were obtained under both standard solvent‐free and solvent‐mediated conditions, and by microwave irradiation. The solid‐state structures of [BiPh(MBT)2]2 and [Bi(MBT)3]2, were determined using single‐crystal X‐ray diffraction, showing them to be dimeric. The bactericidal properties of the complexes against Mycobacterium smegmatis, Staphylococcus aureus, methicillin‐resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, vancomycin‐resistant Enterococcus (VRE) and Escherichia coli revealed [BiPh(MBT)2]2 to be the most effective against all the bacteria with MIC values of 0.6 μg/mL (0.25 μM) against S. aureus and 0.9 μg/mL (0.27 μM) against E. faecalis. [Bi(MBT)3]2 was less active overall. However, comparisons with the analogous complex [Bi(4‐BrMTD)3], revealed a significant hundred‐fold enhanced activity against S. aureus, MRSA, VRE, and E. faecalis. Both complexes showed little or no toxicity towards mammalian COS‐7 cells at 20 μg/mL. [BiPh(MBT)2]2 also was found to display good antileishmanial activity with an IC50 value of 0.11 μg/mL (0.17 μM), at which concentration the complex was non‐toxic to human fibroblast cells.
Formation of Different Isomers of Phosphine–Imidazolyl and –Pyridyl Ruthenium(II) Complexes Affecting the Catalyst Activity in the Acceptorless Dehydrogenation of Alcohols
Authors: Langer Robert , Gese Alexander , Gesevičius Donatas , Jost Maximilian , Langer Bastian R. , Schneck Felix , Venker Alexander , Xu Weiqin 
Published: January 2015

AbstractThe synthesis, reactivity, and catalytic activity of RuII complexes with different pyridine‐ and imidazole‐based P,N ligands are reported. The investigations reveal a strong influence of the N‐heterocycle and the steric demand of the phosphine groups on the stability of different isomers of [L2RuX2] (L = P,N ligand; X = Cl, H). The imidazole‐based complex 5 with dicyclohexylphosphine groups was found to be the most active precatalyst for the acceptorless dehydrogenation of primary alcohols, whereas different phosphine groups at the imidazole ligand as well as pyridine‐based ligands caused a drop in catalytic activity. In the presence of a primary amine, imines are preferentially formed under these conditions. In summary, the investigations show that comparably small changes in the ligand moiety have a strong effect on the relative stability of stereoisomers for both hydride and chloride complexes, whereas isomerization of the kinetic reaction products was observed in some cases. The described changes in the ligand moiety most probably have a strong impact on the relative stabilities of isomeric intermediates as well and thus affect the catalytic activity of these complexes.
A study of the effect of step excrescences and free‐stream disturbances on boundary layer stability
Authors: Sescu Adrian , Visbal Miguel , Rizzetta Donald 
Published: January 2015

SummaryIn this work, a study of the mechanism by which free‐stream acoustic and vorticity disturbances interact with a boundary layer flow developing over a flat plate featuring a step excrescence located at a certain distance from a blunt leading edge is included. The numerical tool is a high‐fidelity implicit numerical algorithm solving for the unsteady, compressible form of the Navier–Stokes equations in a body‐fitted curvilinear coordinates and employing high‐accurate compact differencing schemes with Pade‐type filters. Acoustic and vorticity waves are generated using a source term in the momentum and energy equations, as opposed to using inflow boundary conditions, to avoid spurious waves that may propagate from boundaries. The results show that the receptivity to surface step excrescences is largely the result of an overall adverse pressure gradient posed by the step, and that the free‐stream disturbances accelerate the generation of instabilities in the downstream. As expected, it is found that the acoustic disturbance interacting with the surface imperfection is more efficient in exciting the Tollmien–Schlichting waves than the vorticity disturbance. The latter generates Tollmien–Schlichting waves that are grouped in wave packets consistent with the wavelength of the free‐stream disturbance. Copyright © 2015 John Wiley & Sons, Ltd.