bluuebunny/crossref_metadata_2025_split huggingface dataset:
Materials Issues for Solid Oxide Fuel Cells Design
Authors: Morales Miguel , Segarra Mercè 
Published: July 2015

AbstractSolid oxide fuel cells (SOFCs) are complex electrochemical devices that convert chemical energy into electrical energy with high efficiency. A single cell contains three basic components, which are a porous anode, a dense electrolyte, and a porous cathode. In order to generate high power for a determined application, the single cells are stacked, thus requiring the use of interconnects and sealants. An important challenge of these devices is the reduction of their operating temperatures for improving materials compatibility between components, reducing energy consumption and time for startup and cooling down, and increasing the durability. Many strategies for lowering operating temperature inSOFCs have been proposed. In comparison to other fuel cell types, anSOFCstack can be designed to operate within a wide temperature range (500–1000°C). Therefore, it is necessary to select the desired operation temperature that is mainly influenced by the specific application, the type of fuel, and the properties of solid electrolyte. It is possible to address theSOFCdesign from different approaches: selecting materials for each cell component, selecting cell geometry, or selecting stack design. In this article, different alternatives of materials selection, cell geometry, and stack design, depending on the operating temperatures and compatibilities among materials, are presented.
Cryogenic Energy Storage
Authors: Ding Yulong , Li Yongliang , Li Dacheng , Radcliffe Jonathan , Huang Yun 
Published: July 2015

AbstractCryogenic energy storage (CES) is a large‐scale energy storage technology that uses cryogen (liquid air/nitrogen) as a medium and also a working fluid for energy storage and discharging processes. During off‐peak hours, when electricity is at its cheapest and demand for electricity is at its lowest, liquid air/nitrogen is produced in an air liquefaction and separation plant and stored in cryogenic tanks close to the atmospheric pressure. During peak hours, the cryogenic liquid is heated up using environmental heat and then superheated using other heat sources (if available). The boiling of the cryogenic liquid will form a high pressure gas that drives an expansion device to produce shaft power or electricity. The concept ofCESwas first proposed by University of Newcastle upon Tyne (United Kingdom) in 1977 as an alternative to compressed air energy storage (CAES) technology for peak shaving in an electricity grid. Subsequently, the topic was investigated both numerically and experimentally by both industrial companies such as Mitsubishi Heavy Industries, Hitachi, Expansion Energy, and Highview Power Storage Systems and academic institutions. It is, however, the work from 2005 at the University of Leeds in collaboration with Highview Power Storage Systems that led to the world's first fully operationalMWhpilot grid‐connected plant.
Integration of Energy Storage into Energy Systems
Authors: Hauer Andreas , Teuffel Amadeus 
Published: July 2015

AbstractThe definition of energy storage is followed by an overview of investigated energy storage technologies in the fields of electrical energy storage, thermal energy storage, and storage by chemical conversion. Storage capacity, power, efficiency, storage period, and costs are thereby introduced as important energy storage properties.The role of energy storage in the energy system is highlighted, and relevant energy storage applications for the integration of renewable electricity and renewable thermal energy are presented. Parameters for technical comparison of energy storage technologies are shown whereby it is explained that storage technologies can only be compared within their actual application.Lastly, economics of energy storage are discussed, and maximum acceptable storage costs are introduced as a measure for the evaluation of storage technologies' economics depending on storage cycle periods and investment environment.
Hydrogen Production by Electrolysis and Photoelectrochemical System
Authors: Sim Uk , Jin Kyoungsuk , Oh Seungtaeg , Jeong Donghyuk , Moon Junsang , Oh Jihun , Nam Ki Tae 
Published: July 2015

AbstractHydrogen energy has been drawing much attention in renewable energy technologies. Hydrogen production by water splitting reaction has especially been widely studied as an environmentally friendly and sustainable energy source. Realization of cost‐effective hydrogen production by water splitting requires electrolysis or photoelectrochemical cells decorated with highly efficient cocatalysts. Here, we briefly summarize the theory of water splitting reaction and discuss various types of catalysts for water splitting reaction (hydrogen evolution reaction and oxygen evolution reaction). Principles of photoelectrochemical hydrogen evolution from light absorbing semiconductors will be described.
Palladium‐Catalyzed Alkene Carboamination Reactions of Electron‐Poor Nitrogen Nucleophiles
Authors: Peterson Luke J. , Wolfe John P. 
Published: July 2015

AbstractModified reaction conditions that facilitate Pd‐catalyzed alkene carboamination reactions of electron‐deficient nitrogen nucleophiles are reported. Pent‐4‐enylamine derivatives bearing N‐tosyl or N‐trifluoroacetyl groups are coupled with aryl triflates to afford substituted pyrrolidines in good yield. These reactions proceed via a mechanism involving anti‐aminopalladation of the alkene, which differs from previously reported analogous reactions of N‐aryl‐ and N‐Boc‐pentenylamines. The application of these conditions to a formal synthesis of (±)‐aphanorphine is also described.magnified image
Efficient E‐Selective Transfer Semihydrogenation of Alkynes by Means of Ligand‐Metal Cooperating Ruthenium Catalyst
Authors: Musa Sanaa , Ghosh Amrita , Vaccaro Luigi , Ackermann Lutz , Gelman Dmitri 
Published: July 2015

AbstractThe manuscript describes an efficient protocol for the E‐selective transfer semihydrogenation of internal alkynes employing a previously described bifunctional ruthenium‐based PC(sp3)P complex, 20 mol% of sodium formate and nearly stoichiometric formic acid. Semihydrogenation of the terminal alkynes results in the formation of the corresponding styrenes. The mechanism of the reaction includes stepwise transfer of both the hydride and the proton of the formic acid to the substrate. This fact allowed for the development of a facile protocol for the synthesis of monodeuterated alkenes by simply applying formic acid/sodium formate/D2O mixture as a hydrogen source. High yields, selectivity and functional group compatibility have been generally achieved.magnified image
Enantioselective Hydroalkynylation of Non‐Polar Carbon‐Carbon Double Bonds: Iridium‐Catalyzed Asymmetric Addition Reaction of Terminal Alkyne CH Bonds to Substituted Norbornadienes
Authors: Yang Qingjing , Choy Pui Ying , Fan Baomin , Kwong Fuk Yee 
Published: July 2015

AbstractThis update describes the enantioselective addition of the terminal alkynyl CH bond across a non‐polar CC double bond. Sterically congested substrates are often challenging in this type of reaction as these alkenyl substrates exhibit poor substrate‐metal center coordination, and thus poor stereo‐induction would result. The successful enantioselective hydroalkynylation of this type of system has sporadically been reported. We herein describe our progress for the example of vinyl‐substituted norbornadiene derivatives. With the aid of an iridium complex in combination with the chiral SYNPHOS ligand, the addition products could be obtained smoothly with excellent enantioselectivities (up to 99% ee). In particular, the first examples of an acetylenic CH bond adding across azanorbornadienes are also disclosed.magnified image
A Structural and Functional Model for the 1‐Aminocyclopropane‐1‐carboxylic Acid Oxidase
Authors: Sallmann Madleen , Oldenburg Fabio , Braun Beatrice , Réglier Marius , Simaan A. Jalila , Limberg Christian 
Published: July 2015

AbstractThe hitherto most realistic low‐molecular‐weight analogue for the 1‐aminocyclopropane‐1‐carboxylic acid oxidase (ACCO) is reported. The ACCOs 2‐His‐1‐carboxylate iron(II) active site was mimicked by a TpFe moiety, to which the natural substrate ACC could be bound. The resulting complex [TpMe,PhFeACC] (1), according to X‐ray diffraction analysis performed for the nickel analogue, represents an excellent structural model, featuring ACC coordinated in a bidentate fashion—as proposed for the enzymatic substrate complex—as well as a vacant coordination site that forms the basis for the first successful replication also of the ACCO function: 1 is the first known ACC complex that reacts with O2 to produce ethylene. As a FeOOH species had been suggested as intermediate in the catalytic cycle, H2O2 was tested as the oxidant, too, and indeed evolution of ethylene proceeded even more rapidly to give 65 % yield.
Iron‐Catalyzed Cross‐Coupling of Alkenyl Acetates
Authors: Gärtner Dominik , Stein André Luiz , Grupe Sabine , Arp Johannes , Jacobi von Wangelin Axel 
Published: July 2015

AbstractStable CO linkages are generally unreactive in cross‐coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross‐couplings because the strong CO bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron‐catalyzed cross‐coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 °C, 2 h) with a ligand‐free catalyst (1–2 mol %).
The effect of the ring opening polymerization and chain spacing on the coefficient of thermal expansion and modulus of polyimide
Authors: Yoo Taewon , Kim Kwangin , Jang Wonbong , Han Haksoo 
Published: July 2015

ABSTRACTThe features of norbornene (NE) cross‐linked polyimide (PI) were investigated as the ratio of the norbornene monomer was varied. The coefficient of thermal expansion and modulus are important parameters of materials used in the microelectronic industry. Therefore, in this study, 5‐norbornene‐2, 3‐dicarboxylic acid (NE) was introduced as a crosslinking agent to increase the thermal stability at elevated temperatures. 4,4′‐Benzophenonetetracarboxylic dianhydride was utilized as a dianhydride and 4,4′‐diaminodiphenyl ether was introduced as a diamine monomer. By changing the ratio of each monomer, we were able to control the spacing of the chain and ring opening polymerization, which resulted in improved properties. Each sample was thermally cured which led to a ring opening mechanism of the norbornene through the reverse Diels‐Alder reaction. Thermal mechanical analysis was utilized to determine the coefficient of thermal expansion and dynamic mechanical analysis was used to determine the storage modulus (ε′) and loss modulus (ε″) of the PI film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42607.
Functionalized Carbon Nanotubes for Biomass Conversion: The Base‐Free Aerobic Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid over Platinum Supported on a Carbon Nanotube Catalyst
Authors: Zhou Chunmei , Deng Weiping , Wan Xiaoyue , Zhang Qinghong , Yang Yanhui , Wang Ye 
Published: July 2015

AbstractThe aerobic oxidation of 5‐hydroxymethylfurfural (HMF) into 2,5‐furandicarboxylic acid (FDCA) is one of the most attractive reactions to establish biomass‐based sustainable chemical processes. Supported Au and Pt catalysts have mainly been reported for this reaction, but excess amounts of base additives are generally required, which makes the process less green. Here, we demonstrate that Pt nanoparticles loaded on functionalized carbon nanotubes (CNTs) can catalyze the aerobic oxidation of HMF to FDCA in water without any base additives. Kinetic studies suggest a tandem reaction mechanism via 2,5‐diformylfuran and 5‐formylfurancarboxylic acid intermediates. It has been clarified that the oxygen‐containing functional groups, in particular carbonyl/quinone and/or phenol groups, on CNT surfaces play crucial roles in FDCA formation. These functional groups could enhance the adsorption of HMF as well as the reaction intermediates from water and might facilitate hydrogen transfer.
The Change in Antioxidant Properties of Dextran‐Coated Redox Active Nanoparticles Due to Synergetic Photoreduction–Oxidation
Authors: Barkam Swetha , Das Soumen , Saraf Shashank , McCormack Rameech , Richardson David , Atencio Leonel , Moosavifazel Vanessa , Seal Sudipta 
Published: July 2015

AbstractNanoparticles have proven to be novel material with resourceful applications in the field of nanomedicine. Cerium oxide nanoparticles (CNPs) coated with dextran (Dex–CNPs) have been shown to exhibit anticancer properties which is attributed to the change in oxidation states mediated at the oxygen vacancies on the surface of CNPs. In this study, the extreme sensitivity of Dex–CNPs to visible light is demonstrated using room light with a clear indication of synergetic phenomenon of photoreduction of CNPs in the presence of dextran which undergoes simultaneous oxidation. The phenomenon was further confirmed through a systematic time‐based expedited study using a high intensity visible light source. The physiochemical changes of Dex–CNPs such as dispersion stability, pH, surface chemistry, antioxidant property, cytotoxicity and the surrounding microenvironment of Dex–CNPs were significantly altered on exposure to visible light, thereby affecting the biological response. Given the significance of nanoparticles which are widely researched nanomaterials, in different fields of nanotechnology and biomedicine, this study demonstrates the significant changes in physiochemical properties of Dex–CNPs with light. The photoreduction of Dex–CNPs affects its bifunctional applications in cancer therapy and thereby this study puts forward the necessity to preserve and sustain their properties through proper storage.
Synthesis, Molecular Structure, and Chiroptical Properties of Dibenzylidene Derivatives of Bicyclo[3.3.1]nonane and Brexane
Authors: Stončius Sigitas , Neniškis Algirdas , Loganathan Nagarajan , Wendt Ola F. 
Published: July 2015

AbstractSynthesis of several enantiomerically pure unsaturated bicyclo[3.3.1]nonane and related brexane (tricyclo[4.3.0.03,7]nonane) derivatives bearing exocyclic benzylidene substituents from readily available (+)‐(1S,5S)‐bicyclo[3.3.1]nonane‐2,6‐dione was accomplished. Molecular geometry and chiroptical properties of compounds with enone and styrene chromophores were studied by X‐ray diffraction analysis, molecular modeling, and circular dichroism (CD) spectroscopy. Difunctional 3,7‐dibenzylidenebicyclo[3.3.1]nonanes, such as 2 and 7, 8, 9, exhibited intense CD couplets, arising from the exciton coupling between the two unsaturated chromophores. The observed negative sign of the exciton couplets is congruent with the negative twist (negative chirality) defined by the two interacting transition dipoles. The sign of the Cotton effect corresponding to the π→π* transitions in the CD spectra of monoenone 4 and tricyclic brexane acetate 11 was correlated with the intrinsic dissymmetry (helicity) of the styrene chromophore. Chirality 27:728–737, 2015. © 2015 Wiley Periodicals, Inc.
Chemieunterricht und Chemiedidaktik an berufsbildenden Schulen
Authors: Laudonia Ivano , Eilks Ingo 
Published: July 2015

AbstractBeiträge zur beruflichen Bildung sind in den Zeitschriften der deutschsprachigen Chemiedidaktik eher selten. Aber auch an berufsbildenden Schulen findet Chemieunterricht statt. Dieser Beitrag diskutiert die Stellung und den Stand des Chemieunterrichts an berufsbildenden Schulen im deutschsprachigen Raum. Ausgewählte Trends aus der Didaktik der beruflichen Bildung werden diskutiert und mit Entwicklungen in der allgemeinbildenden Chemiedidaktik in Beziehung gesetzt.
Silicone als Bindeglied zwischen anorganischer und organischer Chemie aus fachlicher und fachdidaktischer Sicht
Authors: Feierabend Timo , Haucke Kerstin , Mowka Marie‐Ann 
Published: July 2015

AbstractObwohl uns Silicone in allen Bereichen des Alltags begegnen und sie sich durch ihre nützlichen Eigenschaften einen festen Platz im Haushalt, im Auto oder im Baubereich erobert haben, wird ihr Einsatz nicht immer positiv bewertet. So werden z. B. aktuell Debatten um die negativen Auswirkungen von Siliconen in Haarpflegeprodukten geführt. Dem gegenüber steht der Wunsch nach Erhalt von Kulturdenkmälern, die zum Schutz mit Siliconen behandelt werden. Trotz der Präsenz dieser Stoffklasse besteht bei Schülerinnen und Schülern nur ein geringes Fachwissen über Silicone. Der Hauptgrund hierfür liegt sicherlich darin, dass das Element Silicium und die darauf basierenden Silicone als Unterrichtsinhalte in den Lehrplänen der verschiedenen Bundesländer eine eher untergeordnete Rolle spielen und häufig nur als fakultative Inhalte für den Chemieunterricht ausgewiesen werden. Aus diesem Grund wurden im Rahmen zweier Qualifikationsarbeiten experimentelle und konzeptionelle Herangehensweisen für die Schwerpunkte Silicone im Bautenschutz und Silicone in der Haarkosmetik entwickelt. Im Artikel werden ausgewählte Ergebnisse zum Schwerpunkt Silicone im Bautenschutz vorgestellt. Auszüge aus der Qualifikationsarbeit mit dem Schwerpunkt Silicone in der Haarkosmetik werden als Online‐Ergänzung zur Verfügung gestellt. Die Ergebnisse beider Arbeiten können Anregungen für eine kontroverse Diskussion zum Einsatz von Siliconen liefern. Im Artikel wird darüber hinaus aufgezeigt, wie das Thema Silicone auch in der Lehreraus‐ und ‐fortbildung sowie im Rahmen einer Schülerakademie integriert werden kann.
Aptamer for imaging and therapeutic targeting of brain tumor glioblastoma
Authors: Delač Mateja , Motaln Helena , Ulrich Henning , Lah Tamara T. 
Published: July 2015

AbstractAptamers are short single‐stranded nucleic acids (RNA or ssDNA), identified by an in vitro selection process, denominated SELEX, from a partially random oligonucleotide library. They bind to a molecular target, a protein or other complex macromolecular structures of interest with high affinity and specificity, comparable to those of antibodies. Recently, aptamer selection protocols were developed for targeting living cells, including tumors. Chemical modifications of the aptamers and modalities of their detection and delivery systems are already available with high selectivity and targeting ability for the desired cancer cell type, making them promising for diagnosis and therapy. Glioblastoma multiformae represents the most malignant and fatal stage of glioma, and is also the most frequent brain tumor. Glioblastoma‐specific aptamers were developed by either targeting the whole cell surface or known glioma biomarkers. These aptamers may gain importance for imaging, tumor cell isolation from biopsies and drug delivery. In biomedical imaging techniques, aptamers coupled with radionuclide or fluorescent labels, bioconjugates and nanoparticles offer an advanced, noninvasive manner for defining the glioblastoma tissue border. Though single modality aptamer imaging probes have some limitations, these are overcome by the use of multimodal probes. Due to selectivity and chemical characteristics, aptamers can be coupled to functionalized nanoparticles and loaded with a drug, appeared promising for in vivo targeting of glioblastoma. Finally, aptamers are effective mediators for gene silencing when coupled to small interfering RNA and a viral vector, thus providing a novel tool with enhanced targeting capability in drug delivery, designed for tailored treatment of glioblastoma patients. © 2015 International Society for Advancement of Cytometry
Prediction of thrombo‐embolic risk in patients with hypertrophic cardiomyopathy (HCMRisk‐CVA)
Authors: Guttmann Oliver P. , Pavlou Menelaos , O'Mahony Constantinos , Monserrat Lorenzo , Anastasakis Aristides , Rapezzi Claudio , Biagini Elena , Gimeno Juan Ramon , Limongelli Giuseppe , Garcia‐Pavia Pablo , McKenna William J. , Omar Rumana Z. , Elliott Perry M. ,   for the Hypertrophic Cardiomyopathy Outcomes Investigators
Published: July 2015

AbstractAimsAtrial fibrillation (AF) and thrombo‐embolism (TE) are associated with reduced survival in hypertrophic cardiomyopathy (HCM), but the absolute risk ofTEin patients with and withoutAFis unclear. The primary aim of this study was to derive and validate a model for estimating the risk ofTEinHCM. Exploratory analyses were performed to determine predictors ofTE, the performance of theCHA2DS2‐VAScscore, and outcome with vitamin K antagonists (VKAs).Methods and resultsA retrospective, longitudinal cohort of seven institutions was used to develop multivariable Cox regression models fitted with pre‐selected predictors. Bootstrapping was used for validation. Of 4821HCMpatients recruited between 1986 and 2008, 172 (3.6%) reached the primary endpoint of cerebrovascular accident (CVA), transient ischaemic attack (TIA), or systemic peripheral embolus within 10 years. A total of 27.5% of patients had aCHA2DS2‐VAScscore of 0, of whom 9.8% developedTEduring follow‐up. Cox regression revealed an association betweenTEand age,AF, the interaction between age andAF,TEprior to first evaluation,NYHAclass, left atrial (LA) diameter, vascular disease, and maximalLVwall thickness. There was a curvilinear relationship betweenLAsize andTErisk. The model predictedTEwith a C‐index of 0.75 [95% confidence interval (CI) 0.70–0.80] and the D‐statistic was 1.30 (95%CI1.05–1.56).VKAtreatment was associated with a 54.8% (95%CI31–97%,P= 0.037) relative risk reduction inHCMpatients withAF.ConclusionsThe study shows that the risk ofTEinHCMpatients can be identified using a small number of simple clinical features.LAsize, in particular, should be monitored closely, and the assessment and treatment of conventional vascular risk factors should be routine practice in older patients. Exploratory analyses show for the first time evidence for a reduction ofTEwithVKAtreatment. TheCHA2DS2‐VAScscore does not appear to correlate well with the clinical outcome in patients withHCMand should not be used to assessTErisk in this population.
A Double‐Cavity‐Containing Porphyrin Host as a Highly Stable Epoxidation Catalyst
Authors: Thomassen Paul J. , Varghese Shaji , Bijsterveld Edward J. A. , Thordarson Pall , Elemans Johannes A. A. W. , Rowan Alan E. , Nolte Roeland J. M. 
Published: July 2015

AbstractWe describe a manganese porphyrin catalyst containing two adjacent cavities, which can be used for the epoxidation of alkenes by sodium hypochlorite. A pyridine ligand bound in one of the cavities regulates the rate and selectivity of the epoxidation reaction that takes place in the adjoining cavity. Pyridine binding studies suggest that site‐to‐site communication exists between the two cavities. The alkene substrates are completely converted into epoxides by the manganese double‐cavity catalyst, but the observed epoxidation rates are low. These low rates are proposed to be a result of the energetically less favourable binding of the substrate into the cavity containing the active site due to an allosteric pinching effect. In the manganese double‐cavity arrangement the catalytically active manganese complex is efficiently protected against decomposition, leading to a catalytic system with enhanced stability. The presented work may open a new route to the construction of highly stable catalysts of which the activity and selectivity may eventually be controlled by allosteric interactions.