bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancement of l‐phenylalanine production in Escherichia coli by heterologous expression of Vitreoscilla hemoglobin
Authors: Wu Wei‐Bin , Guo Xiao‐Lei , Zhang Ming‐Liang , Huang Qing‐Gen , Qi Feng , Huang Jian‐Zhong 
Published: September 2017

Abstractl‐Phenylalanine is an important amino acid that is widely used in the production of food flavors and pharmaceuticals. Generally, l‐phenylalanine production by engineered Escherichia coli requires a high rate of oxygen supply. However, the coexpression of Vitreoscilla hemoglobin gene (vgb), driven bya tac promoter, with the genes encoding 3‐deoxy‐d‐arabinoheptulosonate‐7‐phosphate synthetase (aroF) and feedback‐resistant chorismate mutase/prephenate dehydratase (pheAfbr), led to increased productivity and decreased demand for aeration by E. coli CICC10245. Shake‐flask studies showed that vgb‐expressing strains displayed higher rates of oxygen uptake, and l‐phenylalanine production under standard aeration conditions was increased. In the aerobic fermentation process, cell growth, l‐phenylalanine production, and glucose consumption by the recombinant E. coli strain PAPV, which harbored aroF, pheAfbr, and tac‐vgb genes, were increased compared to that in the strain harboring only aroF and pheAfbr (E. coli strain PAP), especially under oxygen‐limited conditions. The vgb‐expressing strain PAPV produced 21.9% more biomass and 16.6% more l‐phenylalanine, while consuming only approximately 5% more glucose after 48 H of fermentation. This study demonstrates a method to enhance the l‐phenylalanine production by E. coli using less intensive and thus more economical aeration conditions.
The Hidden Cost of Insurance on Cooperation
Authors: van de Calseyde Philippe P.F.M. , Keren Gideon , Zeelenberg Marcel 
Published: September 2017

AbstractA common solution to mitigate risk is to buy insurance. Employing the trust game, we find that buying insurance against the risk of betrayal has a hidden cost: trustees are more likely to act opportunistically when trustors choose to be insured against the breach of trust. Supposedly, trustees are less likely to cooperate when trustors buy insurance because choosing insurance implicitly signals that the trustor expects the trustee to behave opportunistically, paradoxically encouraging trustees not to cooperate. These results shed new light on the potential drawbacks of financial safeguards that are intended to minimize the risky nature of trust taking: the presumed safeguard against the risk of betrayal may, under certain circumstances, increase the probability of betrayal. Copyright © 2017 John Wiley & Sons, Ltd.
Characterization of ectonucleoside triphosphate diphosphohydrolase (E‐NTPDase; EC 3.6.1.5) activity in mouse peritoneal cavity cells
Authors: Dias Dhébora Albuquerque , de Barros Penteado Bruna , dos Santos Lucas Derbocio , dos Santos Pedro Mendes , Arruda Carla Cardozo Pinto , Schetinger Maria Rosa Chitolina , Leal Daniela Bitencourt Rosa , dos Santos Jaques Jeandre Augusto 
Published: September 2017

This study aimed to characterize the activity of ectonucleoside triphosphate diphosphohydrolase (E‐NTPDase; EC 3.6.1.5) in peritoneal cavity cells from BALB/c mice. E‐NTPDase was activated in the presence of both calcium (1.5mM) and magnesium (1.5mM) ions. However, the activity was higher in the presence of Ca2+. A pH of 8.5 and temperature of 37°C were the optimum conditions for catalysis. The apparent Km values were 0.51mM and 0.66mM for the hydrolysis of adenosine triphosphate (ATP) and adenosine diphosphate (ADP), respectively. The Vmax values were 136.4 and 120.8 nmol Pi/min/mg of protein for ATPase and ADPase activity, respectively. Nucleotide hydrolysis was inhibited in the presence of sodium azide (20mM, ATP: P < .05; ADP: P < .001), sodium fluoride (20mM; ATP and ADP: P < .001), and suramin (0.3mM; ATP: P < .01; ADP: P < .05), which is a known profile for NTPDase inhibition. Although all of the diphosphate and triphosphate nucleotides that were tested were hydrolyzed, enzyme activity was increased when adenine nucleotides were used as substrates. Finally, we stress that knowledge of the E‐NTPDase catalytic biochemical properties in mouse peritoneal cavity cells is indispensable for properly determining its activity, as well as to fully understand the immune response profile in both healthy and sick cells.
Activation of the mitochondrial apoptotic pathway contributes to methotrexate‐induced small intestinal injury in rats
Authors: Natarajan Kasthuri , Abraham Premila , Kota Rekha 
Published: September 2017

The efficacy of methotrexate (MTX), a commonly used chemotherapeutic drug, is limited by intestinal injury. As the mechanism of MTX‐induced small intestinal injury is not clear, there is no definitive treatment for MTX‐induced gastrointestinal injury. The present study investigates the role of mitochondrial apoptotic pathway in MTX‐induced small intestinal injury and examines whether aminoguanidine is effective in preventing the damage. Eight Wistar rats were administered 3 consecutive i.p. injections of 7 mg/kg body wt. MTX. Some rats were pretreated with 30 mg or 50 mg/kg body wt. of aminoguanidine (n = 6 in each group). Protein expressions of cytochrome c, caspases 3 and 9, and PARP‐1 were determined in the small intestines by immunohistochemistry and western blot. Mitochondrial pathway of apoptosis was activated in the small intestines of MTX‐treated rats as evidenced by intense immunostaining for cyt c, caspases 9 and 3, and PARP‐1 and mitochondrial release of cyt c, activation of caspases, and PARP‐1 cleavage by Western blot. Immunofluorescence revealed increased nuclear localization of PARP‐1. Aminoguanidine pretreatment ameliorated MTX‐induced small intestinal injury in dose‐dependent manner and inactivated the mitochondrial apoptotic pathway. Aminoguanidine may possess beneficial intestinal protective effects as an adjuvant co‐drug against MTX intestinal toxicity during cancer chemotherapy. As the mechanism of MTX‐induced small intestinal injury is not clear, there is no definitive treatment for MTX‐induced gastrointestinal injury. The results of the present study show that the mitochondrial pathway of apoptosis plays a role in MTX‐induced small intestinal injury as evidenced by cytochrome c release, activation of caspases 9 and 3, PARP‐1 cleavage, and DNA fragmentation. Aminoguanidine (AG) pretreatment attenuates the severity of small‐intestinal injury induced in rats by MTX treatment. The mechanisms of action of AG involve inhibition of iNOS, and mitochondrial pathway of apoptosis. It is suggested that aminoguanidine may possess beneficial intestinal protective effects as an adjuvant co‐drug against MTX intestinal toxicity during cancer chemotherapy.
Visualizing the Adenylation Activities and Protein–Protein Interactions of Aryl Acid Adenylating Enzymes
Authors: Ishikawa Fumihiro , Kasai Shota , Kakeya Hideaki , Tanabe Genzoh 
Published: September 2017

AbstractStructural and activity studies have revealed the dynamic and transient actions of carrier protein (CP) activity in primary and secondary metabolic pathways. CP‐mediated interactions play a central role in nonribosomal peptide biosynthesis, as they serve as covalent tethers for amino acid and aryl acid substrates and enable the growth of peptide intermediates. Strategies are therefore required to study protein–protein interactions efficiently. Herein, we describe activity‐based probes used to demonstrate the protein–protein interactions between aryl CP (ArCP) and aryl acid adenylation (A) domains as well as the substrate specificities of the aryl acid A domains. If coupled with in‐gel fluorescence imaging, this strategy allows visualization of the protein–protein interactions required to recognize and transfer the substrate to the partner ArCP. This technique has potential for the analysis of protein–protein interactions within these biosynthetic enzymes at the molecular level and for use in the combinatorial biosynthesis of new nonribosomal peptides.
Metal–Organic Framework Mediated Synthesis of Small‐Sized γ‐Alumina as a Highly Active Catalyst for the Dehydration of Glycerol to Acrolein
Authors: Huang Liang , Qin Feng , Huang Zhen , Zhuang Yan , Ma Jianxue , Xu Hualong , Shen Wei 
Published: September 2017

AbstractThe dehydration of glycerol into acrolein was investigated over small‐sized γ‐Al2O3 prepared by a metal–organic framework (MOF) templated method. The particle size of alumina strongly affected the final physicochemical properties of γ‐Al2O3 as well as its catalytic activity. The MOF‐derived, small‐sized γ‐Al2O3 (M‐Al2O3) catalyst exhibited higher stability and higher activity in the glycerol dehydration reaction than conventional bulk γ‐Al2O3 and nanorod γ‐Al2O3 owing to enriched intercrystal mesopores and an abundance of accessible acid sites. M‐Al2O3 retained its high glycerol conversion (over 80 %) for nearly 200 h, whereas high acrolein selectivity (74 %) was achieved.
Nanohybrids of Two‐Dimensional Transition‐Metal Dichalcogenides and Titanium Dioxide for Photocatalytic Applications
Authors: Rahmanian Elham , Malekfar Rasoul , Pumera Martin 
Published: September 2017

AbstractThe ever increasing need for renewable and clean energy resources as well as environmental concerns are considered as two serious challenges of today's society. Photocatalysis has proved to be a reliable and effective technology to overcome these issues. However, to bring the full potential of this approach into reality, two main hurdles of fast charge recombination and the limited visible light absorption should be tackled. To address these obstacles, nanocomposites based on titanium dioxide nanostructures and semiconducting two‐dimensional transition‐metal dichalcogenides have been developed and proven to be excellent photocatalysts. In this review, we will overview the recent developments on the fabrication and rational design of these nanocomposites both for hydrogen production and photocatalytic degradation of pollutants with emphasis on those appealing structures.
Gas Adsorption Studies of CO2 in Carbon Nanomaterials: A Case Study of Vertically Aligned Carbon Nanotubes
Authors: Babu Deepu J. , Schneider Jörg J. 
Published: September 2017

AbstractWith their well‐defined pore structure and chemical composition, vertically aligned carbon nanotubes (VACNTs) offer the possibility for a combined theoretical and experimental investigation of their gas adsorption behavior. Due to their nearly ideal 1D structure they offer a defined morphology in which a variety of structural parameters can be tailored. Subsequently the influence of curvature, packing density, adsorption site topology, inner and outer adsorptive surface as well as the influence of functional groups/heteroatoms on CO2 adsorption characteristics can be studied.
Scale‐up of the Synthesis of Zeolitic Imidazolate Framework ZIF‐4
Authors: Hovestadt Maximilian , Vargas Schmitz Jürgen , Weissenberger Tobias , Reif Florian , Kaspereit Malte , Schwieger Wilhelm , Hartmann Martin 
Published: September 2017

AbstractA new synthesis route for the zeolitic imidazolate framework ZIF‐4 is reported. About 200 g of ZIF‐4 are prepared by sonothermal synthesis from ZnO at room temperature. The ZIF‐4 prepared by sonothermal synthesis is comparable to the ZIF‐4 synthesized by the pathway reported in literature with respect to the powder X‐ray diffraction pattern, particle size, and separation potential for olefin‐paraffin gas mixtures. Moreover, the separation potential of ZIF‐4 is compared to commercial adsorbents like carbon molecular sieves and zeolites.
OLED Reloaded: Die Synthese des Halbleiterpolymers MEH‐PPV als Schulversuch
Authors: Banerji Amitabh , Schönbein Ann‐Kathrin , Wolff Johanna 
Published: September 2017

AbstractOrganische Leuchtdioden (OLEDs) sind moderne Leuchtmittel der nächsten Generation. Sie verwenden (u. a.) halbleitende Polymere für die Lichtemission und erschließen völlig neuartige Anwendungsgebiete wie flexible oder transparente Displays und Leuchten. Für die Implementation von OLEDs in den Chemieunterricht wurden bereits low‐cost Experimente und Lehr‐Lern‐Materialien bereitgestellt. Dieser Beitrag erweitert das Thema um die Synthese eines Halbleiterpolymers im Schulversuch und präsentiert ein gelungenes Beispiel für die curriculare Innovation durch die Kooperation zwischen der Fachdidaktik und Fachwissenschaft.
Lebensmittel natürlich oder technologisch verändert? – Beispiele einer Kooperation zwischen Schule und Hochschule zum Kontext Lebensmitteltechnologie
Authors: Wentorf Wilfried , Keppler Julia K. , Knipp Jörg R. , Parchmann Ilka , Schwarz Karin 
Published: September 2017

AbstractDieser Artikel zeigt anhand der Lebensmitteltechnologie Beispiele für die direkte Kooperation von Fachwissenschaft, Schule und Didaktik bei der Erschließung und Ausgestaltung neuer Unterrichtskonzepte und Unterrichtsmaterialien. Die Erforschung von Molkenproteinen als mögliche „Nanotransporter“ in Lebensmitteln wird als Unterrichtsgang anhand konkreter Arbeitsblätter vorgestellt. Dabei erhalten Schülerinnen und Schüler gleichzeitig Einblicke in das vielschichtige Tätigkeitsfeld von Naturwissenschaftlerinnen und Naturwissenschaftlern, wie es das Konstrukt „Nature of Scientists“ vorsieht.
Redox‐Flow‐Batterien – Organische Batterien mit Zukunftsperspektiven
Authors: Rosenberg Dominique , Pansegrau Svenja , Wachholz Mirco , Rehling Alexander , Busker Maike , Jansen Walter 
Published: September 2017

AbstractRedox‐Flow‐Batterien auf Basis von Vanadium‐Verbindungen werden derzeit als Energiespeicher erprobt, um im Rahmen des Ausbaus der erneuerbaren Energien entstehende Einspeisespitzen und Nachfrageschwankungen zu kompensieren. Vanadium‐Verbindungen sind aufgrund ihrer Toxizität für den Chemieunterricht nicht geeignet. Um dieses Thema für den Chemieunterricht zur erschließen, werden in Anlehnung an die Arbeiten der Arbeitsgruppen um Aziz und Narayanan Experimente unter Verwendung von Hydrochinonen und Chinonen entwickelt. In diesem Artikel werden grundlegende Versuche, in denen auf die Arbeiten von Aziz und Narayanan eingegangen wird, präsentiert sowie organische Batterien unter der Verwendung von Alltagsmaterialien vorgestellt.
Selective and Efficient Iridium Catalyst for the Reductive Amination of Levulinic Acid into Pyrrolidones
Authors: Wang Shengdong , Huang Haiyun , Bruneau Christian , Fischmeister Cédric 
Published: September 2017

AbstractThe catalytic reductive amination of levulinic acid (LA) into pyrrolidones with an iridium catalyst using H2 as hydrogen source is reported. The chemoselective iridium catalyst displayed high efficiency for the synthesis of a variety of N‐substituted 5‐methyl‐2‐pyrrolidones and N‐arylisoindolinones. N‐Substituted 5‐methyl‐2‐pyrrolidone was also evaluated as a biosourced substitute solvent to NMP (N‐methylpyrrolidone) in the catalytic arylation of 2‐phenylpyridine.
Co9S8/Co as a High‐Performance Anode for Sodium‐Ion Batteries with an Ether‐Based Electrolyte
Authors: Zhao Yingying , Pang Qiang , Wei Yingjin , Wei Luyao , Ju Yanming , Zou Bo , Gao Yu , Chen Gang 
Published: September 2017

AbstractCo9S8 has been regarded as a desirable anode material for sodium‐ion batteries because of its high theoretical capacity. In this study, a Co9S8 anode material containing 5.5 wt % Co (Co9S8/Co) was prepared by a solid‐state reaction. The electrochemical properties of the material were studied in carbonate and ether‐based electrolytes (EBE). The results showed that the material had a longer cycle life and better rate capability in EBE. This excellent electrochemical performance was attributed to a low apparent activation energy and a low overpotential for Na deposition in EBE, which improved the electrode kinetic properties. Furthermore, EBE suppressed side reactions of the electrode and electrolyte, which avoided the formation of a solid electrolyte interphase film.
Predictive mapping of the biotic condition of conterminous U.S. rivers and streams
Authors: Hill Ryan A. , Fox Eric W. , Leibowitz Scott G. , Olsen Anthony R. , Thornbrugh Darren J. , Weber Marc H. 
Published: September 2017

AbstractUnderstanding and mapping the spatial variation in stream biological condition could provide an important tool for conservation, assessment, and restoration of stream ecosystems. The USEPA's 2008–2009 National Rivers and Streams Assessment (NRSA) summarizes the percentage of stream lengths within the conterminous United States that are in good, fair, or poor biological condition based on a multimetric index of benthic invertebrate assemblages. However, condition is usually summarized at regional or national scales, and these assessments do not provide substantial insight into the spatial distribution of conditions at unsampled locations. We used random forests to model and predict the probable condition of several million kilometers of streams across the conterminous United States based on nearby and upstream landscape features, including human‐related alterations to watersheds. To do so, we linked NRSA sample sites to the USEPA's StreamCat Dataset; a database of several hundred landscape metrics for all 1:100,000‐scale streams and their associated watersheds within the conterminous United States. The StreamCat data provided geospatial indicators of nearby and upstream land use, land cover, climate, and other landscape features for modeling. Nationally, the model correctly predicted the biological condition class of 75% of NRSA sites. Although model evaluations suggested good discrimination among condition classes, we present maps as predicted probabilities of good condition, given upstream and nearby landscape settings. Inversely, the maps can be interpreted as the probability of a stream being in poor condition, given human‐related watershed alterations. These predictions are available for download from the USEPA's StreamCat website. Finally, we illustrate how these predictions could be used to prioritize streams for conservation or restoration.
Active dissemination of cellular antigens by DCs facilitates CD8+ T‐cell priming in lymph nodes
Authors: Gurevich Irina , Feferman Tali , Milo Idan , Tal Orna , Golani Ofra , Drexler Ingo , Shakhar Guy 
Published: September 2017

AbstractAntigen (Ag) specific activation of naïve T cells by migrating dendritic cells (DCs) is a highly efficient process, although the chances for their colocalization in lymph nodes (LNs) appear low. Ag presentation may be delegated from Ag‐donor DCs to the abundant resident DCs, but the routes of Ag transfer and how it facilitates T‐cell activation remain unclear. We visualized CD8+ T cell‐DC interactions to study the sites, routes, and cells mediating Ag transfer in mice. In vitro, Ag transfer from isolated ovalbumin (OVA)+ bone marrow (BM) DCs triggered widespread arrest, Ca2+ flux, and CD69 upregulation in OT‐I T cells contacting recipient DCs. Intravital two‐photon imaging revealed that survival of Ag‐donor DCs in LNs was required for Ag dissemination among resident CD11c+ DCs. Upon interaction with recipient DCs, CD8+ T cells clustered, upregulated CD69, proliferated and differentiated into effectors. Few DCs sufficed for activation, and for efficient Ag dissemination lymphocyte function associated antigen 1 (LFA‐1) expression on recipient DCs was essential. Similar findings characterized DCs infected with a replication‐deficient OVA‐expressing Vaccinia virus known to downregulate MHC‐I. Overall, active Ag dissemination from live incoming DCs helped activate CD8+ T cells by increasing the number of effective presenting cells and salvaged T‐cell priming when Ag‐donor DCs could not present Ag.
Stability of supraglacial debris
Authors: Moore Peter L. 
Published: September 2017

AbstractRock debris on the surface of ablating glaciers is not static, and is often transported across the ice surface as relief evolves during melt. This supraglacial debris transport has a strong influence on the spatial distribution of melt, and is implicated in the formation of hummocky glacial topography in deglaciated terrain. Furthermore, as ice‐dammed lakes and ice‐cored slopes become increasingly common in deglaciating watersheds, there is rising concern about hazards to humans and infrastructure posed by mass‐wasting of ice‐cored debris. The existing quantitative framework for describing these debris transport processes is limited, making it difficult to account for transport in mass balance, hazard assessment, and landscape development models. This paper develops a theoretical framework for assessing slope stability and gravitational mass transport in a debris‐covered ice setting. Excess water pressure at the interface between ablating ice and lowering debris is computed by combining Darcy's law with a meltwater balance. A limit‐equilibrium slope stability analysis is then applied to hypothetical debris layers with end‐member moisture conditions derived from a downslope meltwater balance that includes production and seepage. The resulting model system constrains maximum stable slope angles and lengths that vary with debris texture, thickness, and the rate of meltwater production. Model predictions are compared with field observations and with digital elevation model (DEM)‐derived terrain metrics from two modern debris‐covered glaciers on Mount Rainier, USA. Copyright © 2017 John Wiley & Sons, Ltd.
Flexibility as firm value driver: Evidence from offshore outsourcing
Authors: Choi Jongmoo J. , Ju Ming , Kotabe Masaaki , Trigeorgis Lenos , Zhang Xiaotian T. 
Published: September 2017

Research SummaryThis article tests real options theory predictions that uncertainty and flexibility are key value drivers for offshore outsourcing moderated by switching costs. Examining firm‐specific and market data for outsourcing cases by U.S. firms, we find that the impact of market and environmental uncertainty and flexibility on outsourcing value is net positive and that it is greater for offshore than for domestic outsourcing. Outsourcing benefits are related to flexibility arising from growth options and moderated by switching costs underlying outsourcing activities, including loss of innovative capability and economic, institutional, and cross‐country cultural differences.Managerial SummaryIn the popular business literature, the “footloose” nature of outsourcing strategy characterized by an outsourcing firm's flexibility, as well as the ability in finding appropriate suppliers on a global basis, has often been touted as an important means of dealing with market uncertainty. However, the academic literature has not offered direct empirical support for the inherent value of such outsourcing strategies. Our study shows that firms tend to perform better financially when they have such outsourcing flexibility under uncertain market and environmental conditions, although this relationship may be somewhat weakened by potential loss of innovative capability and cultural and other differences in dealing with foreign suppliers.