bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resin Acid Conversion with CYP105A1: An Enzyme with Potential for the Production of Pharmaceutically Relevant Diterpenoids
Authors: Janocha Simon , Zapp Josef , Hutter Michael , Kleser Michael , Bohlmann Jörg , Bernhardt Rita 
Published: February 2013

AbstractCytochrome P450s are very versatile enzymes with great potential for biotechnological applications because of their ability to oxidize unactivated CH bonds. CYP105A1 from Streptomyces griseolus was first described as a herbicide‐inducible sulfonylurea hydroxylase, but it is also able to convert other substrates such as vitamin D3. To extend the substrate pool of this interesting enzyme further, we screened a small diterpenoid compound library and were able to show the conversion of several resin acids. Binding of abietic acid, dehydroabietic acid, and isopimaric acid to the active site was assayed, and Vmax and Km values were calculated. The products were analyzed by NMR spectroscopy and identified as 15‐hydroxyabietic acid, 15‐hydroxydehydroabietic acid, and 15,16‐epoxyisopimaric acid. As the observed products are difficult to obtain by chemical synthesis, CYP105A1 has proved to be a promising candidate for biotechnological applications that combine bioconversion and chemical synthesis to obtain functionalized resin acids.
Role of Emulsifiers in Emulsion Technology and Emulsion Crystallization
Authors: Petersen S. , Ulrich J. 
Published: February 2013

AbstractHigh‐pressure homogenization as an emulsification technique and the production of solid lipid nanoparticles are strongly interlinked. The impact of an emulsifier as an important influencing parameter for both processes is described exemplarily for Polysorbate 20 and sodium caseinate. Regarding the emulsification process, Polysorbate 20 led to a higher improvement of the droplet breakup than the protein sodium caseinate. These results were compared with different published investigations on the crystallization behavior of fats with the same emulsifiers. Considering the crystallization behavior of the lipid phase, sodium caseinate was more advantageous in stabilization of the crystallized particles. The most important factors which have to be taken into account were determined and analyzed.
Detection of Potential TNA and RNA Nucleoside Precursors in a Prebiotic Mixture by Pure Shift Diffusion‐Ordered NMR Spectroscopy
Authors: Islam Saidul , Aguilar Juan A. , Powner Matthew W. , Nilsson Mathias , Morris Gareth A. , Sutherland John D. 
Published: February 2013

AbstractIn the context of prebiotic chemistry, one of the characteristics of mixed nitrogenous‐oxygenous chemistry is its propensity to give rise to highly complex reaction mixtures. There is therefore an urgent need to develop improved spectroscopic techniques if onerous chromatographic separations are to be avoided. One potential avenue is the combination of pure shift methodology, in which NMR spectra are measured with greatly improved resolution by suppressing multiplet structure, with diffusion‐ordered spectroscopy, in which NMR signals from different species are distinguished through their different rates of diffusion. Such a combination has the added advantage of working with intact mixtures, allowing analyses to be carried out without perturbing mixtures in which chemical entities are part of a network of reactions in equilibrium. As part of a systems chemistry approach towards investigating the self‐assembly of potentially prebiotic small molecules, we have analysed the complex mixture arising from mixing glycolaldehyde and cyanamide, in a first application of pure shift DOSY NMR to the characterisation of a partially unknown reaction composition. The work presented illustrates the potential of pure shift DOSY to be applied to chemistries that give rise to mixtures of compounds in which the NMR signal resolution is poor. The direct formation of potential RNA and TNA nucleoside precursors, amongst other adducts, was observed. These preliminary observations may have implications for the potentially prebiotic assembly chemistry of pyrimidine threonucleotides, and therefore of TNA, by using recently reported chemistries that yield the activated pyridimidine ribonucleotides.
Modification of a Small β‐Barrel Protein, To Give Pseudo‐Amyloid Structures, Inhibits Amyloid β‐Peptide Aggregation
Authors: Murakoshi Yuko , Takahashi Tsuyoshi , Mihara Hisakazu 
Published: February 2013

AbstractAggregation of amyloid β‐peptide (Aβ) is closely related to the pathogenesis of Alzheimer’s disease (AD). Although much effort has been devoted to the construction of molecules that inhibit the aggregation of Aβ1‐42, high doses are needed for the inhibition of Aβ aggregation in many cases. Previously, we reported that designed green fluorescent protein (GFP) analogues that gives pseudo‐Aβ β‐sheet structures can work as an aggregation inhibitor against Aβ. To further test this design strategy, we constructed protein analogues that mimic Aβ β‐sheet structures of amyloids by using insulin‐like growth factor 2 receptor domain 11 (IGF2R‐d11) as a scaffold. A designed protein, named IG11KK, which has a parallel configuration of Aβ‐like β sheets, can bind more preferentially to oligomeric Aβ1‐42 than the monomer. Moreover, IG11KK suppressed the aggregation of Aβ1‐42 efficiently, even though lower concentrations of IG11KK than Aβ were used. The aggregation kinetics of Aβ in the presence of the designed proteins revealed that IG11KK can work as an inhibitor not only for the early to middle stages, but also in the latter stage of Aβ aggregation owing to its favorable binding to oligomeric structures of Aβ. The design strategy using β‐barrel proteins such as IGF2R‐d11 and GFP is useful in generating excellent inhibitors of protein misfolding and amyloid formation.
Solid‐State Thermolysis of a fac‐Rhenium(I) Carbonyl Complex with a Redox Non‐Innocent Pincer Ligand
Authors: Jurca Titel , Chen Wen‐Ching , Michel Sheila , Korobkov Ilia , Ong Tiow‐Gan , Richeson Darrin S. 
Published: February 2013

AbstractThe development of rhenium(I) chemistry has been restricted by the limited structural and electronic variability of the common pseudo‐octahedral products fac‐[ReX(CO)3L2] (L2=α‐diimine). We address this constraint by first preparing the bidentate bis(imino)pyridine complexes [(2,6‐{2,6‐Me2C6H3NCPh}2C5H3N)Re(CO)3X] (X=Cl 2, Br 3), which were characterized by spectroscopic and X‐ray crystallographic means, and then converting these species into tridentate pincer ligand compounds, [(2,6‐{2,6‐Me2C6H3NCPh}2C5H3N)Re(CO)2X] (X=Cl 4, Br 5). This transformation was performed in the solid‐state by controlled heating of 2 or 3 above 200 °C in a tube furnace under a flow of nitrogen gas, giving excellent yields (≥95 %). Compounds 4 and 5 define a new coordination environment for rhenium(I) carbonyl chemistry where the metal center is supported by a planar, tridentate pincer‐coordinated bis(imino)pyridine ligand. The basic photophysical features of these compounds show significant elaboration in both number and intensity of the d–π* transitions observed in the UV/Vis spec tra relative to the bidentate starting materials, and these spectra were analyzed using time‐dependent DFT computations. The redox nature of the bis(imino)pyridine ligand in compounds 2 and 4 was examined by electrochemical analysis, which showed two ligand reduction events and demonstrated that the ligand reduction shifts to a more positive potential when going from bidentate 2 to tridentate 4 (+160 mV for the first reduction step and +90 mV for the second). These observations indicate an increase in electrostatic stabilization of the reduced ligand in the tridentate conformation. Elaboration on this synthetic methodology documented its generality through the preparation of the pseudo‐octahedral rhenium(I) triflate complex [(2,6‐{2,6‐Me2C6H3NCPh}2C5H3N)Re(CO)2OTf] (7, 93 % yield).
Cleanability of Surfaces from Active Pharmaceutical Ingredient Surrogate Riboflavin by Falling Film
Authors: Lerch Katja , Hinrichs Jörg , Dittmer Patrizia , Rauschnabel Johannes 
Published: February 2013

AbstractFalling films in wash down process are of major interest for pharmaceutical isolators, which are used for processing of highly potent pharmaceutical products. In this study multiple process parameters were examined with common materials of isolator systems. The importance of material and surface finish in respect of cleanability and complete wetting as well as a combination of process parameters are presented and discussed. For cleaning validation an effect of high interest was discovered: swab sampling areas changed their properties over many repeated cycles and showed decreased cleanability.
POM‐Catalyzed In Situ Ligand Synthesis for the Construction of Metal Complexes and Their Use in the Formation of Coordination Polymers
Authors: Dey Chandan , Banerjee Rahul 
Published: February 2013

AbstractSix organic–inorganic hybrid materials were synthesized by the in situ oxidation of neocuproine by using MoO3/Na2MoO4 as the catalyst in the presence of Cu(NO3)2. The crystal structures of Mo8‐Cu4‐PHEN and Mo8‐Cu2‐5(2PIC) are composed of [Mo8O26]4− polyoxometalate (POM) units, whereas the crystal structure of Mo6‐Cu‐COPHEN is composed of a [Mo6O19]2− POM unit; both POM units could be considered as the active form of the catalyst. Reaction of the hybrid materials with 1,3,5‐benzenetricarboxylic acid (BTC) resulted in the formation of two different coordination polymers (CPs) under different reaction conditions. These CPs, depending on their structural attributes, exhibit distinct differences in the adsorption of H2, CO2, and water. The use of 2‐methylpyridine instead of neocuproine does not give any oxidation products under the same reaction conditions due to the incorrect positioning of the methyl group with respect to the CuII center.
On the Photoabsorption by Permanganate Ions in Vacuo and the Role of a Single Water Molecule. New Experimental Benchmarks for Electronic Structure Theory
Authors: Houmøller Jørgen , Kaufman Sydney H. , Støchkel Kristian , Tribedi Lokesh C. , Brøndsted Nielsen Steen , Weber J. Mathias 
Published: February 2013

AbstractWe report electronic spectra of mass‐selected MnO4− and MnO4−⋅H2O using electronic photodissociation spectroscopy. Bare MnO4− fragments by formation of MnO3− and MnO2−, while the hydrated complex predominantly decays by loss of the water molecule. The band in the visible spectral region shows a well‐resolved vibrational progression consistent with the excitation of a MnO stretching mode. The presence of a single water molecule does not significantly perturb the spectrum of MnO4−. Comparison with the UV/Vis absorption spectrum of permanganate in aqueous solution shows that complete hydration causes a small blueshift, while theoretical models including a dielectric medium have predicted a redshift. The experimental data can be used as benchmarks for electronic structure theory methods, which usually predict electronic spectra in the absence of a chemical environment.
Effect of oxygen partial pressure on the marangoni flow of molten metals
Authors: Hibiya Taketoshi , Ozawa Shumpei 
Published: February 2013

AbstractMeasurements of surface tension of molten silver and iron are reviewed. Surface tension of molten silver and iron show boomerang‐shaped behavior; the maximum surface tension appears at a certain temperature, below which temperature coefficient of surface tension is positive. Due to change of temperature coefficient, Marangoni flow direction shows variation in a liquid bridge configuration.
Unraveling the Interfacial Electron Transfer Dynamics of Electroactive Microbial Biofilms Using Surface‐Enhanced Raman Spectroscopy
Authors: Ly Hoang K. , Harnisch Falk , Hong Siang‐Fu , Schröder Uwe , Hildebrandt Peter , Millo Diego 
Published: February 2013

AbstractThe electron transfer (ET) processes of electroactive microbial biofilms have been investigated by combining electrochemistry and time‐resolved surface‐enhanced resonance Raman (TR‐SERR) spectroscopy. This experimental approach provides selective information on the ET process across the biofilm–electrode interface by monitoring the redox‐state changes of heme cofactors in outer membrane cytochromes (OMCs) that are in close vicinity (i.e., within 7 nm) to the Ag working electrode. The rate constant for heterogeneous ET of the surface‐confined OMCs (sc‐OMCs) of a mixed culture derived electroactive microbial biofilm has been determined to be 0.03 s−1. In contrast, according to kinetic simulations the ET between sc‐OMCs and their redox partners, embedded within the biofilm, is a much faster process with an estimated rate constant greater than 1.2 s−1. The slow rate of heterogeneous ET and the lack of high‐spin species in the SERR spectra rule out the direct attachment of the sc‐OMCs to the electrode surface.
Secure multicast routing protocols in mobile ad‐hoc networks
Authors: Moamen Ahmed Abdel , Hamza Haitham S. , Saroit Iman A. 
Published: February 2013

SUMMARYA mobile ad‐hoc network (MANET) is a collection of autonomous nodes that communicate with each other by forming a multi‐hop radio network. Routing protocols in MANETs define how routes between source and destination nodes are established and maintained. Multicast routing provides a bandwidth‐efficient means for supporting group‐oriented applications. The increasing demand for such applications coupled with the inherent characteristics of MANETs (e.g., lack of infrastructure and node mobility) have made secure multicast routing a crucial yet challenging issue. Recently, several multicast routing protocols (MRP) have been proposed in MANETs. Depending on whether security is built‐in or added, MRP can be classified into two types: secure and security‐enhanced routing protocols, respectively. This paper presents a survey on secure and security‐enhanced MRP along with their security techniques and the types of attacks they can confront. A detailed comparison for the capability of the various routing protocols against some known attacks is also presented and analyzed. Copyright © 2013 John Wiley & Sons, Ltd.
Generalized Synthesis of Mesoporous Rare Earth Oxide Thin Films through Amphiphilic Ionic Block Copolymer Templating
Authors: Xiao Ying , You Shusen , Yao Yuan , Zheng Tao , Lin Chen , Roth Stephan V. , Müller‐Buschbaum Peter , Steffen Werner , Sun Ling‐Dong , Yan Chun‐Hua , Gutmann Jochen S. , Yin Meizhen , Fu Jun , Cheng Ya‐Jun 
Published: February 2013

AbstractA new concept to achieve the generalized synthesis of crystalline mesoporous rare earth (RE) oxide thin films templated with an ionic amphiphilic block copolymer is developed. Mesoporous La2O3, Eu2O3, Tb2O3, and Yb2O3 thin films as representatives of the light and heavy RE groups are synthesized by using polystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA) as a templating agent. The impact of the concentration of PS‐b‐PAA on the morphologies of the mesopores is investigated. The local and long‐range lateral structures, vertical structures, and crystallinities of the mesoporous thin films are probed by scanning electron microscopy, atomic force microscopy, grazing‐incidence small‐angle X‐ray scattering, X‐ray reflectivity, and transmission electron microscopy. The mechanism of formation of the mesoporous RE oxide thin films is discussed.
Oxidative Trimerization of Catechol to Hexahydroxytriphenylene
Authors: Morimoto Koji , Dohi Toshifumi , Kita Yasuyuki 
Published: February 2013

AbstractDirect oxidative coupling is an attractive tool for environmentally benign green chemistry. We report the novel oxidative synthesis of hexahydroxytriphenylene by using a hypervalent iodine reagent. The reaction proceeds under very mild conditions for reducing acid waste and in a very short time at room temperature.
Shaking table test on the seismic failure characteristics of a subway station structure on liquefiable ground
Authors: Chen Guoxing , Wang Zhihua , Zuo Xi , Du Xiuli , Gao Hongmei 
Published: February 2013

SUMMARYIn order to investigate the seismic failure characteristics of a structure on the liquefiable ground, a series of shaking table tests were conducted based on a plaster model of a three‐story and three‐span subway station. The dynamic responses of the structure and ground soil under main shock and aftershock ground motions were studied. The sand boils and waterspouts phenomena, ground surface cracks, and earthquake‐induced ground surface settlements were observed in the testing. For the structure, the upward movement, local damage and member cracking were obtained. Under the main shock, there appeared longer liquefaction duration for the ground soil while the pore pressure dissipated slowly. The acceleration amplification effect of the liquefied soil was weakened, and the soil showed a remarkable shock absorption and concentration effect with low frequency component of ground motion. However, under the aftershock, the dissipation of pore pressure in the ground soil became obvious. The peak acceleration of the structure reduced with the buried depth. Dynamic soil pressure on the side wall was smaller in the middle and larger at both ends. The interior column of the model structure was the weakest member. The peak strain and damage degree for both sides of the interior column exhibited an ‘S’ type distribution along the height. Moreover, the seismic response of both ground soil and subway station structure exhibited a remarkable spatial effect. The seismic damage development process and failure mechanism of the structure illustrated in this study can provide references for the engineers and researcher. Copyright © 2013 John Wiley & Sons, Ltd.
PERFLUORINATED COMPOUND CONCENTRATIONS IN GREAT BLUE HERON EGGS NEAR ST. PAUL, MINNESOTA, USA, IN 1993 AND 2010–2011
Authors: Custer Thomas W. , Dummer Paul M. , Custer Christine M. , Wu Qian , Kannan Kurunthachalam , Trowbridge Annette 
Published: February 2013

Abstract

A great blue heron (Ardea herodias) colony on Pig's Eye Island on the Mississippi River near St. Paul, Minnesota, USA, is located near several potential perfluorinated compound (PFC) sources. The PFC concentrations in great blue heron eggs reported from a 1993 collection from the Pig's Eye colony were among the highest measured in bird eggs worldwide. The objective of this investigation was to determine whether PFC concentrations in great blue heron eggs at the Pig's Eye colony have changed since 1993. Total PFC concentrations in great blue heron eggs collected at the Pig's Eye colony in 2010 and 2011 (geometric mean = 340 and 492 ng/g wet wt) were 60% lower than the 1993 collection (1,015 ng/g wet wt). Among PFCs, perfluoroalkyl sulfonate concentrations were lower and perfluoroalkyl carboxylate concentrations were higher in the 2010 and 2011 collections. Two of 20 (10%) of the eggs analyzed from Pig's Eye in 2010 and 2011 were &gt;1,000 ng PFCs/g wet weight and the maximum PFC value (2,506 ng PFCs/g wet wt) measured in 2010 and 2011 was among the highest PFC concentration reported in bird eggs. These high concentrations are at levels associated with physiological and neurological effects in birds. Environ. Toxicol. Chem. 2013;32:1077–1083. © 2013 SETAC
Use of Segmented Cell Operated in Hydrogen Recirculation Mode to Detect Water Accumulation in PEMFC
Authors: Pérez L. C. , Ihonen J. , Sousa J. M. , Mendes A. 
Published: February 2013

AbstractAdequate water management is crucial to increase stability and durability of Polymer Electrolyte Membrane Fuel Cells. In this paper, a test rig suitable for water balance and nitrogen crossover studies was built around a hydrogen‐air segmented cell and used to indirectly assess flooding or drying conditions in specific zones of the active cell area. In particular, the anode of the segmented cell was operated in recirculation mode with continuous water removal. Current density distribution (CDD) diagrams were obtained for different anode operating parameters, namely, the recirculated gas flow rate, anode pressure, and time between purges. Water accumulation at the electrodes was assessed from CDD diagrams and confirmed using water balance and flow‐patterns calculations. It was concluded that lower recirculation flow rates led to flooding due to decreased water removal capabilities at the anode. For higher recirculation flow rates, drying was observed in one zone of the cell but homogeneous CDD in the other. Finally, the use of partially segment bipolar plates was proposed to increase the in‐plane electrical resistance between adjacent segments. The partial segmentation increased the segment to segment in‐plane electrical resistance between 14 and 21% and decreased the through‐plane to in‐plane resistance ratio by 17%.
Preparation and Characterization of Perfluorosulfonate‐Free Phosphosilicate Glass‐Based Composite Proton‐Exchange Membrane
Authors: Di Z. , Li H. , Li M. , Mao D. , Chen X. , Xiao M. 
Published: February 2013

AbstractBased on hydrothermally treated phosphosilicate (SiO2–P2O5) glass and sulfonated poly(ether ether ketone) (SPEEK) polymer, perfluorosulfonate‐free SiO2–P2O5/SPEEK composite membranes are prepared. The morphology, thermal and mechanical properties, pore structure, proton conductivity, water uptake, as well as the fuel cell performances of the SiO2–P2O5/SPEEK composite membranes are investigated. The SiO2–P2O5/SPEEK composite membranes with proton conductive SiO2–P2O5 glass powders of more than 50 wt.% were determined to be flexible due to the incorporation of the SPEEK polymer component, and it showed proton conductivities of above 10–2 S cm–1. A single H2/O2 fuel cell was assembled based on the SiO2–P2O5/SPEEK composite membrane, and was found to release a peak power density of 355.6 mW cm–2 at 68 °C.
Tropical precipitation and convection changes in the Max Planck Institute Earth system model (MPI‐ESM) in response to CO2 forcing
Authors: Crueger Traute , Hohenegger Cathy , May Wilhelm 
Published: February 2013

Key Points
Convection scheme obeys climate change rules derived from CRM except over land
Link to land surface processes yields different precipitation sensitivity to CO2
Tropical deep convection gets less frequent (‐5.5%/K) and deeper (3.8 %/K)
Response of the middle atmosphere to anthropogenic and natural forcings in the CMIP5 simulations with the Max Planck Institute Earth system model
Authors: Schmidt H. , Rast S. , Bunzel F. , Esch M. , Giorgetta M. , Kinne S. , Krismer T. , Stenchikov G. , Timmreck C. , Tomassini L. , Walz M. 
Published: February 2013

Key Points
Middle atmosphere features of the MPI‐ESM and external data are described
Middle atmosphere response to climate forcing in CMIP5 simulations is discussed
Future middle atmosphere evolution depends strongly on the emission scenario
Nanostructured scaffolds for bone tissue engineering
Authors: Li Xiaoming , Wang Lu , Fan Yubo , Feng Qingling , Cui Fu‐Zhai , Watari Fumio 
Published: February 2013

AbstractIt has been demonstrated that nanostructured materials, compared with conventional materials, may promote greater amounts of specific protein interactions, thereby more efficiently stimulating new bone formation. It has also been indicated that, when features or ingredients of scaffolds are nanoscaled, a variety of interactions can be stimulated at the cellular level. Some of those interactions induce favorable cellular functions while others may leads to toxicity. This review presents the mechanism of interactions between nanoscaled materials and cells and focuses on the current research status of nanostructured scaffolds for bone tissue engineering. Firstly, the main requirements for bone tissue engineering scaffolds were discussed. Then, the mechanism by which nanoscaled materials promote new bone formation was explained, following which the current research status of main types of nanostructured scaffolds for bone tissue engineering was reviewed and discussed. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.