bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigations of Two Bidirectional Carbon Monoxide Dehydrogenases from Carboxydothermus hydrogenoformans by Protein Film Electrochemistry
Authors: Wang Vincent C.‐C. , Ragsdale Stephen W. , Armstrong Fraser A. 
Published: September 2013

AbstractCarbon monoxide dehydrogenases (CODHs) catalyse the reversible conversion between CO and CO2. Several small molecules or ions are inhibitors and probes for different oxidation states of the unusual [Ni‐4 Fe‐4 S] cluster that forms the active site. The actions of these small probes on two enzymes—CODH ICh and CODH IICh—produced by Carboxydothermus hydrogenoformans have been studied by protein film voltammetry to compare their behaviour and to establish general characteristics. Whereas CODH ICh is, so far, the better studied of the two isozymes in terms of its electrocatalytic properties, it is CODH IICh that has been characterised by X‐ray crystallography. The two isozymes, which share 58.3 % sequence identity and 73.9 % sequence similarity, show similar patterns of behaviour with regard to selective inhibition of CO2 reduction by CO (product) and cyanate, potent and selective inhibition of CO oxidation by cyanide, and the action of sulfide, which promotes oxidative inactivation of the enzyme. For both isozymes, rates of binding of substrate analogues CN− (for CO) and NCO− (for CO2) are orders of magnitude lower than turnover, a feature that is clearly revealed through hysteresis of cyclic voltammetry. Inhibition by CN− and CO is much stronger for CODH IICh than for CODH ICh, a property that has relevance for applying these enzymes as model catalysts in solar‐driven CO2 reduction.
Heterogenisation of a C‐Scorpionate FeII Complex on Carbon Materials for Cyclohexane Oxidation with Hydrogen Peroxide
Authors: Martins L. M. D. R. S. , de Almeida M. Peixoto , Carabineiro S. A. C. , Figueiredo J. L. , Pombeiro A. J. L. 
Published: September 2013

AbstractThe hydrotris(pyrazol‐1‐yl)methane iron(II) complex [FeCl2{η3‐HC(pz)3}] (pz=pyrazol‐1‐yl) (1) was immobilized on three different carbon materials (activated carbon, carbon xerogel and multi‐walled carbon nanotubes) with three different surface treatments (original, treated with nitric acid, and treated with nitric acid followed by sodium hydroxide) to produce active, selective and recyclable catalysts. The heterogenisation process was more efficient for carbon nanotubes treated with nitric acid and sodium hydroxide. An outstanding improved catalytic performance of complex 1 upon heterogenisation on carbon nanotubes treated with nitric acid and sodium hydroxide (turnover numbers up to 5.6×103 and overall yield of 21 %), relative to the homogeneous system, was achieved for the single‐pot peroxidative oxidation of cyclohexane to the cyclohexanone and cyclohexanol mixture. The heterogenised systems allowed their easy recovery and reuse, at least for five consecutive cycles, maintaining 96 % of the initial activity and concomitant rather high selectivity to cyclohexanol and cyclohexanone.
Synthesis, Characterization, and Reactivity of Cobalt(III)–Oxygen Complexes Bearing a Macrocyclic N‐Tetramethylated Cyclam Ligand
Authors: Kim Doyeon , Cho Jaeheung , Lee Yong‐Min , Sarangi Ritimukta , Nam Wonwoo 
Published: September 2013

AbstractMononuclear metal–dioxygen species are key intermediates that are frequently observed in the catalytic cycles of dioxygen activation by metalloenzymes and their biomimetic compounds. In this work, a side‐on cobalt(III)–peroxo complex bearing a macrocyclic N‐tetramethylated cyclam (TMC) ligand, [CoIII(15‐TMC)(O2)]+, was synthesized and characterized with various spectroscopic methods. Upon protonation, this cobalt(III)–peroxo complex was cleanly converted into an end‐on cobalt(III)–hydroperoxo complex, [CoIII(15‐TMC)(OOH)]2+. The cobalt(III)–hydroperoxo complex was further converted to [CoIII(15‐TMC‐CH2‐O)]2+ by hydroxylation of a methyl group of the 15‐TMC ligand. Kinetic studies and 18O‐labeling experiments proposed that the aliphatic hydroxylation occurred via a CoIV–oxo (or CoIII–oxyl) species, which was formed by OO bond homolysis of the cobalt(III)–hydroperoxo complex. In conclusion, we have shown the synthesis, structural and spectroscopic characterization, and reactivities of mononuclear cobalt complexes with peroxo, hydroperoxo, and oxo ligands.
Longitudinal Relaxation Enhancement in 1H NMR Spectroscopy of Tissue Metabolites via Spectrally Selective Excitation
Authors: Shemesh Noam , Dumez Jean‐Nicolas , Frydman Lucio 
Published: September 2013

AbstractNuclear magnetic resonance spectroscopy is governed by longitudinal (T1) relaxation. For protein and nucleic acid experiments in solutions, it is well established that apparent T1 values can be enhanced by selective excitation of targeted resonances. The present study explores such longitudinal relaxation enhancement (LRE) effects for molecules residing in biological tissues. The longitudinal relaxation recovery of tissue resonances positioned both down‐ and upfield of the water peak were measured by spectrally selective excitation/refocusing pulses, and compared with conventional water‐suppressed, broadband‐excited counterparts at 9.4 T. Marked LRE effects with up to threefold reductions in apparent T1 values were observed as expected for resonances in the 6–9 ppm region; remarkably, statistically significant LRE effects were also found for several non‐exchanging metabolite resonances in the 1–4 ppm region, encompassing 30–50 % decreases in apparent T1 values. These LRE effects suggest a novel means of increasing the sensitivity of tissue‐oriented experiments, and open new vistas to investigate the nature of interactions among metabolites, water and macromolecules at a molecular level.
Studies on Photocatalytic CO2 Reduction over NH2‐Uio‐66(Zr) and Its Derivatives: Towards a Better Understanding of Photocatalysis on Metal–Organic Frameworks
Authors: Sun Dengrong , Fu Yanghe , Liu Wenjun , Ye Lin , Wang Dengke , Yang Lin , Fu Xianzhi , Li Zhaohui 
Published: September 2013

AbstractMetal–organic framework (MOF) NH2‐Uio‐66(Zr) exhibits photocatalytic activity for CO2 reduction in the presence of triethanolamine as sacrificial agent under visible‐light irradiation. Photoinduced electron transfer from the excited 2‐aminoterephthalate (ATA) to Zr oxo clusters in NH2‐Uio‐66(Zr) was for the first time revealed by photoluminescence studies. Generation of ZrIII and its involvement in photocatalytic CO2 reduction was confirmed by ESR analysis. Moreover, NH2‐Uio‐66(Zr) with mixed ATA and 2,5‐diaminoterephthalate (DTA) ligands was prepared and shown to exhibit higher performance for photocatalytic CO2 reduction due to its enhanced light adsorption and increased adsorption of CO2. This study provides a better understanding of photocatalytic CO2 reduction over MOF‐based photocatalysts and also demonstrates the great potential of using MOFs as highly stable, molecularly tunable, and recyclable photocatalysts in CO2 reduction.
σ‐Hole Bond Versus Hydrogen Bond: From Tetravalent to Pentavalent N, P, and As Atoms
Authors: Grabowski Sławomir J. 
Published: September 2013

AbstractAb initio calculations were performed on complexes of ZH4+(Z=N, P, As) and their fluoro derivatives, ZFH3+and ZF4+, with a HCN (or LiCN) molecule acting as the Lewis base through the nitrogen electronegative center. It was found that the complexes are linked by the ZH⋅⋅⋅N hydrogen bond or another type of noncovalent interaction in which the tetravalent heavy atom of the cation acts as the Lewis acid center, that is, when the Z⋅⋅⋅N link exists, which may be classified as the σ‐hole bond. The formation of the latter interaction is usually preferable to the formation of the corresponding hydrogen bond. The Z⋅⋅⋅N interaction may be also considered as the preliminary stage of the SN2 reaction. This is supported by the observation that for a short Z⋅⋅⋅N contact, the corresponding complex geometry coincides with the trigonal‐bipyramidal geometry typical for the transition state of the SN2 reaction. The Z⋅⋅⋅N interaction for some of complexes analyzed here possesses characteristics typical for covalent bonds. Numerous interrelations between geometrical, topological and energetic parameters are discussed. The natural bond orbital method as well as the Quantum Theory of “Atoms in Molecules” is applied to characterize interactions in the analyzed complexes. The experimental evidences of the existence of these interactions, based on the Cambridge Structure Database search, are also presented. In addition, it is justified that mechanisms of the formation of the Z⋅⋅⋅N interactions are similar to the processes occurring for the other noncovalent links. The formation of Z⋅⋅⋅N interaction as well as of other interactions may be explained with the use of the σ‐hole concept.
Cyclization of Homopropargyl Chalcogenides by Copper(II) Salts: Selective Synthesis of 2,3‐Dihydroselenophenes, 3‐Arylselenophenes, and 3‐Haloselenophenes/thiophenes
Authors: Schumacher Ricardo F. , Rosário Alisson R. , Leite Marlon R. , Zeni Gilson 
Published: September 2013

AbstractCopper(II) halide mediated cyclization of homopropargyl chalcogenides gave three types of chalcogenophene derivatives. Selective product formation was achieved by controlling solvent, temperature, and atmosphere. By using CuBr2 and 1,2‐dichloroethane at room temperature under ambient atmosphere, 4‐bromo dihydroselenophene derivatives were obtained, whereas CuBr2 and 1,2‐dichloroethane at reflux gave selectively 2‐substituted selenophenes. When 1,2‐dichloroethane was replaced by dimethylacetamide, 3‐halo‐selenophenes were obtained exclusively. The versatility of chalcogenophenes was also studied by reaction of 3‐haloselenophenes with terminal alkynes under Sonogashira conditions affording the cross‐coupled products. In addition, the reaction of 3‐haloselenophenes with boronic acids gave the corresponding Suzuki‐type products in good yields.
Electrografting of Diazonium‐Functionalized Polyoxometalates: Synthesis, Immobilisation and Electron‐Transfer Characterisation from Glassy Carbon
Authors: Rinfray Corentin , Izzet Guillaume , Pinson Jean , Gam Derouich Sarra , Ganem Jean‐Jacques , Combellas Catherine , Kanoufi Frédéric , Proust Anna 
Published: September 2013

AbstractPolyoxometalates (POMs) are attractive candidates for the rational design of multi‐level charge‐storage materials because they display reversible multi‐step reduction processes in a narrow range of potentials. The functionalization of POMs allows for their integration in hybrid complementary metal oxide semiconductor (CMOS)/molecular devices, provided that fine control of their immobilisation on various substrates can be achieved. Owing to the wide applicability of the diazonium route to surface modification, a functionalized Keggin‐type POM [PW11O39{Ge(p‐C6H4‐CC‐C6H4‐${{\rm N}{{+\hfill \atop 2\hfill}}}$)}]3− bearing a pending diazonium group was prepared and subsequently covalently anchored onto a glassy carbon electrode. Electron transfer with the immobilised POM was thoroughly investigated and compared to that of the free POM in solution.
Hard X‐ray Spectroscopic Nano‐Imaging of Hierarchical Functional Materials at Work
Authors: Andrews Joy C. , Weckhuysen Bert M. 
Published: September 2013

AbstractHeterogeneous catalysts often consist of an active metal (oxide) in close contact with a support material and various promoter elements. Although macroscopic properties, such as activity, selectivity and stability, can be assessed with catalyst performance testing, the development of relevant, preferably quantitative structure–performance relationships require the use of advanced characterisation methods. Spectroscopic imaging in the hard X‐ray region with nanometer‐scale resolution has very recently emerged as a powerful approach to elucidate the hierarchical structure and related chemistry of catalytic solids in action under realistic reaction conditions. This X‐ray‐based chemical imaging method benefits from the combination of high resolution (∼30 nm) with large X‐ray penetration and depth of focus, and the possibility for probing large areas with mosaic imaging. These capabilities make it possible to obtain spatial and temporal information on chemical changes in catalytic solids as well as a wide variety of other functional materials, such as fuel cells and batteries, in their full complexity and integrity. In this concept article we provide details on the method and setup of full‐field hard X‐ray spectroscopic imaging, illustrate its potential for spatiotemporal chemical imaging by making use of recent showcases, outline the pros and cons of this experimental approach and discuss some future directions for hierarchical functional materials research.
Optimization of Reaction Conditions towards Multiple Types of Framework Isomers and Periodic‐Increased Porosity: Luminescence Properties and Selective CO2 Adsorption over N2
Authors: Wu Xiao‐Liu , Luo Feng , Sun Gong‐Ming , Zheng An‐Min , Zhang Jian , Luo Ming‐Biao , Xu Wen‐Yuan , Zhu Yan , Zhang Xiao‐Min , Huang Shu‐Yun 
Published: September 2013

AbstractThree new metal‐organic frameworks (MOFs) were prepared by solvo(hydro)thermolysis and further characterized as framework isomers. The structural transformation from non‐porous to porous MOFs and the purity of these products can be modulated by controlling the reaction temperature. The periodic‐increased porosity observed was further confirmed by CO2 adsorption isotherms. Owing to the presence of acylamide groups in the pore walls and the flexible nature of the skeleton of these MOFs, highly selective CO2 adsorption over N2 was observed, as well as structure‐dependent periodic varieties in luminescence properties.
The Anxiety Severity Interview for Children and Adolescents: An Individualized Repeated Measure of Anxiety Severity
Authors: Hogendoorn Sanne M. , de Haan Else , Wolters Lidewij H. , Vervoort Leentje , Prins Pier J. M. , de Bourgraaf Annika , Scheerman Nicolien A. C. , Nauta Maaike H. , Hartman Catharina A. , Boer Frits , Goodman Wayne K. 
Published: September 2013

The Anxiety Severity Interview for Children and Adolescents (ASICA) was developed for the repeated assessment of the impact of anxiety and control over anxiety symptoms. The ASICA incorporates three main components of anxiety: physical response, avoidant behaviour and anxious thoughts. The objective of this study was to evaluate the psychometric properties of the ASICA in children with anxiety disorder (n = 139, age 8–18 years) and a non‐anxious control group (n = 40, age 8–18 years). A confirmatory factor analysis confirmed the intended factor structure. Internal reliability was moderate to good; inter‐rater reliability was excellent. Four‐week test‐retest reliability was good. The ASICA discriminated between anxious and non‐anxious children and appeared sensitive to treatment change. A cut‐off score of 13 was determined. Convergent validity with anxiety symptoms was moderate; discriminant validity with depressive symptoms was less strong. The results suggest that the ASICA is a reliable instrument that could be used in clinical practice to repeatedly monitor anxiety severity. Copyright © 2013 John Wiley & Sons, Ltd.Key Practitioner MessageThe ASICA was developed to repeatedly assess anxiety severity in children.The clinician assesses anxious feelings, avoidant behaviour and anxious thoughts.The ASICA discriminates well between anxious and non‐anxious children.The ASICA has good psychometric properties and is treatment sensitive.The ASICA can be used in clinical practice to repeatedly monitor anxiety severity.
Organophosphorus Catalysis to Bypass Phosphine Oxide Waste
Authors: van Kalkeren Henri A. , van Delft Floris L. , Rutjes Floris P. J. T. 
Published: September 2013

AbstractThe conversion of oxygen‐containing compounds is often achieved by the use of phosphorus reagents. The newly formed phosphine oxide bond delivers the enthalpic gain that drives reactions, such as the Wittig, Mitsunobu, and Appel reaction, to completion. However, phosphine oxides are recognized as undesirable waste products and in the past decade several methods have emerged that address this issue by in situ regeneration of the phosphorus reagent. This Minireview outlines the two distinct strategies and underpinning research that led to these advances. The potential of the emerging field of phosphorus catalysis in chemistry is shown and new developments that may stimulate further research are described.
Bauwerksabdichtungen im Mauerwerksbau unter den Herausforderungen des Klimawandels
Authors: Oswald Rainer 
Published: September 2013

AbstractDer Klimawandel hat selbstverständlich Auswirkungen auf die Bauwerksabdichtungen – schließlich soll die Bauwerksabdichtung die Gebäudehülle gegen die wesentliche Klimabeanspruchung durch Niederschläge schützen. Den Mauerwerksbau betreffen unmittelbar die Klimabeanspruchungen im Fassadenbereich sowie im Bereich der erdberührten Bauteile. Hier wird versucht, durch eine klarere Differenzierung und Klassifizierung der zu erwartenden Beanspruchungen angemessen auf die veränderten Bedingungen zu reagieren, ohne durch eine pauschale Verschärfung der Anforderungen die Wirtschaftlichkeit des Bauens zu beeinträchtigen.Über die Änderungen in der Normenstruktur von DIN 18195 und über einige beabsichtigte Neuregelungen in einer neuen DIN 18533 wird im Folgenden berichtet.Waterproofing of masonry constructions under the challenges of climate change. Climate change obviously effects the waterproofing of buildings, since the envelope of a building must be protected against the prevailing climate stresses caused by precipitation. In this context masonry construction has to deal with the climate effects especially on the façade and on below‐ground building components. This essay aims to present clear distinctions and classifications of the predominant stresses, so that one can adequately react to the changing conditions without raising general requirements for buildings and thus making their construction less economical.The following text reports on the structural changes of DIN 18195 and on some new regulations planned for an entirely new DIN 18 533.
Vergabe‐ und Vertragsordnung für Bauleistungen (VOB) – Entwicklung, Bedeutung, Zukunft
Authors: Nolte Johannes 
Published: September 2013

AbstractDer Vortrag beleuchtet neben der Geschichte der VOB und des Deutschen Vergabe‐ und Vertragsausschuss für Bauleistungen (DVA) auch dessen Organisation und seine satzungsgemäßen Aufgaben sowie das Verfahren der Erstellung oder Überarbeitung einer ATV.Zentrales Thema ist die aktuelle Überarbeitung der Allgemeinen Technischen Vertragsbedingungen (ATV) des Hochbaus im Abschnitt 5 “Abrechnung“. Im Auftrag des DVA wurde im Hauptausschuss Hochbau eine neue Struktur für diesen Abschnitt erarbeitet, durch die mehr Klarheit und Transparenz bei den Aufmaßregelungen und der Abrechnung erzielt werden soll.
Auswirkungen künftiger Energiestrukturen auf den Wohnungs‐ und Städtebau
Authors: Sahner Georg , Plachta Timo 
Published: September 2013

AbstractAuf Gebäudeebene hat die Revision der DIN 4108‐2 das Verfahren zum Nachweis des sommerlichen Wärmeschutzes verschärft. In der Praxis bedeutet dies, auch für den Wohnungsbau reduzierte Fensterflächenanteile, erhöhte Verschattung, massivere Konstruktionen und Konzepte für eine erhöhte Nachtlüftung. Während durch schwerere Bauweisen auch der Primärenergiebedarf positiv beeinflusst werden kann, wirken sich Reduzierungen der Fensterflächen oft negativ auf die minimalen Anforderungen an die natürliche Belichtung aus.Auf städtebaulicher Ebene werden Energienutzungspläne und Klimaschutzkonzepte immer wichtiger für die Energiewende. Diese legen nach einer genauen bzw. verorteten Bedarfs‐ und Potentialanalyse erhöhte Anforderungen an Neubaustandards sowie Sanierungsquoten fest, um die jeweiligen Klimaschutzziele der einzelnen Kommunen bzw. Regionen zu erreichen.Energy structures of the future and their impact on housing and urban design. For housing, the revision of DIN 4108‐2 has tightened the procedure for the detection of thermal insulation in summer. This means reduced window area ratios, increased shading, massive structures and concepts for increased night ventilation. The primary energy demand can be positively influenced by heavier constructions, but reduced window area ratios may often act negatively on the minimum requirements for natural lighting.So called “energy use plans” and climate protection concepts are becoming increasingly important for the German energy turnaround. After determining exact and rooted needs and potentials, these concepts appoint requirements for new housing and remidiation rates.Municipalities or regions need such concpets to achieve their goals of climate protection.
Ursachen und Folgen des Klimawandels – ein kurzer Überblick über den Wissensstand mit historischem Kontext
Authors: Rahmstorf Stefan 
Published: September 2013

AbstractSchon fast 200 Jahre kennen Wissenschaftler den Treibhauseffekt. Entstehung, Ausmaß und Folgen der Erderwärmung werden seitdem immer genauer beschrieben. Doch Politik, Wirtschaft und Gesellschaft nehmen alle Warnungen nicht ernst genug. Zunächst gilt es, den globalen Temperaturanstieg gegenüber dem vorindustriellen Niveau im Mittel auf unter zwei Grad Celsius zu begrenzen – eigentlich ein eher bescheidenes Ziel. Es ist ein Kompromiss zwischen dem aus der Sicht der Wissenschaftler Erforderlichen und dem politisch Erreichbaren. Heute sind die Optionen für eine klimafreundlichere Gewinnung und Nutzung von Energie klarer denn je – wir müssen sie nur mit aller Kraft verfolgen, denn die Zeit für ihre Umsetzung läuft uns davon.
Ocean acidification and responses to predators: can sensory redundancy reduce the apparent impacts of elevated CO2 on fish?
Authors: Lönnstedt Oona M. , Munday Philip L. , McCormick Mark I. , Ferrari Maud C. O. , Chivers Douglas P. 
Published: September 2013

AbstractCarbon dioxide (CO2) levels in the atmosphere and surface ocean are rising at an unprecedented rate due to sustained and accelerating anthropogenic CO2 emissions. Previous studies have documented that exposure to elevated CO2 causes impaired antipredator behavior by coral reef fish in response to chemical cues associated with predation. However, whether ocean acidification will impair visual recognition of common predators is currently unknown. This study examined whether sensory compensation in the presence of multiple sensory cues could reduce the impacts of ocean acidification on antipredator responses. When exposed to seawater enriched with levels of CO2 predicted for the end of this century (880 μatm CO2), prey fish completely lost their response to conspecific alarm cues. While the visual response to a predator was also affected by high CO2, it was not entirely lost. Fish exposed to elevated CO2, spent less time in shelter than current‐day controls and did not exhibit antipredator signaling behavior (bobbing) when multiple predator cues were present. They did, however, reduce feeding rate and activity levels to the same level as controls. The results suggest that the response of fish to visual cues may partially compensate for the lack of response to chemical cues. Fish subjected to elevated CO2 levels, and exposed to chemical and visual predation cues simultaneously, responded with the same intensity as controls exposed to visual cues alone. However, these responses were still less than control fish simultaneously exposed to chemical and visual predation cues. Consequently, visual cues improve antipredator behavior of CO2 exposed fish, but do not fully compensate for the loss of response to chemical cues. The reduced ability to correctly respond to a predator will have ramifications for survival in encounters with predators in the field, which could have repercussions for population replenishment in acidified oceans.