bluuebunny/crossref_metadata_2025_split huggingface dataset:
Entwicklung vereinfachter Materialgesetze in Form von temperaturabhängigen Spannungs‐Dehnungs‐Beziehungen für ultrahochfesten Beton
Authors: Richter Ekkehard , Zehfuß Jochen , Kampmeier Björn 
Published: October 2013

AbstractDas Baustoffverhalten von Beton im Hochtemperaturbereich q ≤ 1200 °C wird i. A. mit Hilfe stationärer Druck‐ und instationärer Kriechversuche untersucht. Die unterschiedliche Versuchsdurchführung wird detailliert in den RILEM‐Empfehlungen beschrieben. Die experimentellen Ergebnisse werden anschließend in Form von temperaturabhängigen Spannungs‐Dehnungslinien aufbereitet, die die Grundlage für die numerische Berechnung des Trag‐ und Verformungsverhaltens von brandbeanspruchten Bauteilen darstellen. Bei deren Anwendung müssen die Randbedingungen beachtet werden, wie z. B. die Aufheizgeschwindigkeit. Bereits früher wurde am Beispiel von Normalbeton gezeigt, wie aus den experimentellen Ergebnissen vereinfachte temperaturabhängige Spannungs‐Dehnungslinien ermittelt werden. In diesem Beitrag wird das Vorgehen auf ultrahochfesten Beton angewendet. Die theoretischen Überlegungen und die Ableitung baustoffspezifischer Materialkennwerte werden beispielhaft an der Betonrezeptur B5Q durchgeführt.Developing simplified materials laws in the form of temperature‐dependent stress‐strain relations for ultra high performance concrete. The behaviour of concrete as a building material at temperatures in the region of q ≤ 1200 °C is normally investigated using steady state and transient creep tests. The various experimental methods are described in detail in the RILEM recommendations. The results of the experiments are then displayed in the form of temperature‐dependent stress‐strain diagrams. These diagrams represent the basis for the numerical calculation of the load‐bearing and deformation behaviour of components exposed to fire. When such diagrams are used, the boundary conditions must also be considered, such as the heating rate. The example of normal concrete has already been used to show how simplified temperature‐dependent stress‐strain diagrams may be derived from experimental findings. The present paper applies the same procedure to ultra high performance concrete. As an example, the theoretical considerations and the derivation of building material‐specific parameters are applied to one concrete mix composition.
Untersuchungen zur Festigkeit der Klebefugen von historischem Brettschichtholz
Authors: Rug Wolfgang , Linke Gunter , Winter Leonard 
Published: October 2013

AbstractDer Beitrag befasst sich mit Untersuchungen zur Festigkeit von Kaseinverleimungen von Brettschichtholz in Hetzer‐Bauweise. Kaseinverleimungen treten heutzutage nur noch im Bereich von Instandsetzungsarbeiten an historischen Brettschichtholzkonstruktionen in Erscheinung.Eine Bewertung der Ergebnisse nach der DIN EN 392:1996 erwies sich als ungeeignet, da sich diese Norm auf moderne, auf Kunstharzen basierende Klebstoffsysteme bezieht. Um dennoch eine Bewertung vornehmen zu können, wurde auf frühere Veröffentlichungen zur Festigkeit von Kaseinverleimungen bzw. Regelwerke des Holzflugzeugbaus der 1950er‐Jahre zurückgegriffen.Die Auswertung eigener Untersuchungen ergab, dass Kaseinverleimungen auch nach 100 Jahren Nutzungsdauer, insbesondere unter Wechselwirkung von Feuchtigkeit und chemisch‐aggressiven Medien, eine relativ hohe Tragfähigkeit und Dauerhaftigkeit aufweisen.Studies on the strength of the adhesive joints of historic glued laminated timberThis paper presents a study on the strength of casein glue layers of glulam timber in Hetzer's construction method. Nowadays casein adhesive joints are only appearing in maintenance of historic glulam structures.An evaluation of the results according to DIN EN 392:1996 proved unsuitable, as this standard relates to modern, synthetic resins based adhesive systems. Therefore earlier publications on the strength of casein glue respectively regulations for wooden aircrafts from the 1950s were utilized in order to be able to assess these kind of adhesive joints.The results of this study revealed, that the casein adhesive joint has an relatively high loading capacity and durability even after 100 years especially under interaction of moisture and chemically aggressive media.
Entwurfs‐ und Konstruktionsgrundsätze von extern vorgespannten Straßenbrücken in Segmentbauart, dargestellt am Bangkok Expressway, Thailand.
Authors: Girmscheid G. 
Published: October 2013

AbstractAm Beispiel einer 35 km langen Spannbeton‐Hochstraße in Segmentbauart mit externer Vorspannung und Trockenfuge werden das Prinzip und Vor‐ und Nachteile der Bauart beschrieben.
Imaging and tracing of intracellular metabolites utilizing genetically encoded fluorescent biosensors
Authors: Zhang Chang , Wei Zi‐Han , Ye Bang‐Ce 
Published: October 2013

AbstractIntracellular metabolites play a crucial role in characterizing and regulating corresponding cellular activities. Tracking intracellular metabolites in real time by traditional means was difficult until the powerful toolkit of genetically encoded biosensors was developed. Over the past few decades, iterative improvements of these biosensors have been made, resulting in the effective monitoring of metabolites. In this review, we introduce and discuss the recent advances in the use of genetically encoded biosensors for tracking some key metabolites, such as ATP, cAMP, cGMP, NADH, reactive oxygen species, sugar, carbon monoxide, and nitric oxide. A brief phylogeny of fluorescent proteins and several typical construction modes for genetically encoded biosensors are also described. We also discuss the development of novel RNA‐based sensors, which are genetically encoded biosensors active at the transcriptional level.
Magnetic quantum dots in biotechnology – synthesis and applications
Authors: Mahajan Kalpesh D. , Fan Qirui , Dorcéna Jenny , Ruan Gang , Winter Jessica O. 
Published: October 2013

AbstractQuantum dots (QDs) have great promise in biological imaging, and as this promise is realized, there has been increasing interest in combining the benefits of QDs with those of other materials to yield composites with multifunctional properties. One of the most common materials combined with QDs is magnetic materials, either as ions (e.g. gadolinium) or as nanoparticles (e.g. superparamagnetic iron oxide nanoparticles, SPIONs). The fluorescent property of the QDs permits visualization, whereas the magnetic property of the composite enables imaging, magnetic separation, and may even have therapeutic benefit. In this review, the synthesis of fluorescent–magnetic nanoparticles, including magnetic QDs is explored; and the applications of these materials in imaging, separations, and theranostics are discussed. As the properties of these materials continue to improve, QDs have the potential to greatly impact biological imaging, diagnostics, and treatment.
The use of rice seeds to produce human pharmaceuticals for oral therapy
Authors: Wakasa Yuhya , Takaiwa Fumio 
Published: October 2013

AbstractRice (Oryza sativa L.) is the major staple food consumed by half of the world's population. Rice seeds have gained recent attention as bioreactors for the production of human pharmaceuticals such as therapeutic proteins or peptides. Rice seed production platforms have many advantages over animal cell or microbe systems in terms of cost‐effectiveness, scalability, safety, product stability and productivity. Rice seed‐based human pharmaceuticals are expected to become innovative therapies as edible drugs. Therapeutic proteins can be sequestered within natural cellular compartments in rice seeds and protected from harsh gastrointestinal environments. This review presents the state‐of‐the‐art on the construction of gene cassettes for accumulation of pharmaceutical proteins or peptides in rice seeds, the generation of transgenic rice plants, and challenges involved in the use of rice seeds to produce human pharmaceuticals.
Metabolic Fate of Depsides and Alkaloid Constituents in Aqueous Extracts from Mercurialis perennis L. during Fermentation
Authors: Lorenz Peter , Conrad Jürgen , Stintzing Florian C. 
Published: October 2013

AbstractDog's mercury (Mercurialis perennis L.) is an old medicinal plant, nowadays used in complementary medicine. Aqueous fermented extracts of the plant are being mainly applied in remedies to treat external inflammations, but a thorough phytochemical characterization is still lacking. Therefore, the conversion of characteristic compound classes from M. perennis extracts during fermentation and storage was investigated. The microbial transformation of the two main depsides phaselic acid (=(2R)‐O‐[(E)‐caffeoyl]malic acid; 1) and mercurialis acid (=(2R)‐[(E)‐caffeoyloxy]glutaric acid; 2) was monitored by HPLC‐DAD. The degradation followed a second‐order kinetic, and the calculated half‐life periods of both constituents were 67 and 30 months, respectively. Several depside metabolites were detected by GC/MS in AcOEt extracts as tBuMe2Si (TBDMS) derivatives after derivatization, mainly dihydrocinnamic acids. Moreover, numerous α‐hydroxy acids were found, allegedly as degradation products from amino acids or peptides. The microbial alteration of the main alkaloid hermidin was also examined. After three days of fermentation, three novel N‐metabolites were formed and thoroughly assigned in CH2Cl2 extracts as a mixture of 3‐ethylhermidin, 3‐ethylhermidin quinone, and (E/Z)‐3‐ethylidenehermidin by GC/MS and NMR methods, as well as by means of total synthesis. A mechanism for the formation of these N‐metabolites starting from dimeric hermidin oxidation products is proposed. The obtained results reveal the complex pathways plant constituents may undergo during the fermentation of the extracts.
Variability of the Root Essential Oils of Seseli rigidumWaldst. & Kit. (Apiaceae) from Different Populations in Serbia
Authors: Marčetić Mirjana D. , Lakušić Branislava S. , Lakušić Dmitar V. , Kovačević Nada N. 
Published: October 2013

AbstractThe chemical compositions of the essential oils of seven natural populations of Seseli rigidum were analyzed. The essential‐oil yield ranged from 0.16 to 2.09%. Analysis of variance (ANOVA) revealed that there were no statistically significant differences in the mean essential‐oil yields between the populations, and no significant influence of the climate or soil type on the oil yield was observed. In all 67 analyzed samples, the polyacetylene falcarinol was the main compound, followed by octanal, methyl linoleate, α‐muurolene, 3‐butylphthalide, falcarinone, muurola‐4,10(14)‐dien‐1β‐ol, β‐sesquiphellandrene, salvial‐4(14)‐en‐1‐one, δ‐amorphene, spathulenol, and isospathulenol. The principal component analysis (PCA), the canonical discriminant analysis (CDA), and the cluster analysis (CA) revealed differentiation between the populations based on the climate. Three groups of populations were formed; the first group was composed of samples growing in regions with a humid climate, with oils having high falcarinol and low sesquiterpene contents, and the second and third groups comprised samples exposed to semi‐arid climate, with oils characterized by a lower falcarinol and higher α‐muurolene, δ‐amorphene, β‐sesquiphellandrene, and salvial‐4(14)‐en‐1‐one contents. The semi‐arid populations were divided into two groups, which were distinguished based on the oil contents of sesquiterpenes, falcarinone, and 3‐butylphthalide. On the other hand, no clear separation between populations based on the different soil types could be observed.
Odor Qualities and Thresholds of Physiological Metabolites of 1,8‐Cineole as an Example for StructureActivity Relationships Considering Chirality Aspects
Authors: Kirsch Frauke , Buettner Andrea 
Published: October 2013

AbstractThe present study aimed at analyzing the odor properties of a group of physiological human metabolites of the odorant 1,8‐cineole: 2,3‐dehydro‐, α2,3‐epoxy‐, α/β2‐hydroxy‐, α3‐hydroxy‐, 4‐hydroxy‐, 7‐hydroxy‐, 9‐hydroxy‐, 2‐oxo‐, and 3‐oxo‐1,8‐cineole. These metabolites constitute a group of structurally closely related molecules, which differ mainly in nature and position of O‐containing functional groups. They thus offer the possibility to correlate odor properties with molecular structure, i.e., to establish structureodor relationships of compounds that are biologically generated from a potent odorant as parent substance. Generally, the metabolites preserved the eucalyptus‐like odor quality of 1,8‐cineole but showed additional odor notes such as sweet, citrus‐like, plastic‐like, earthy, musty, and faecal, which made them distinguishable. The individual enantiomers of chiral molecules also exhibited different odors. With the exception of 2,3‐dehydro‐1,8‐cineole, all metabolites showed a highly decreased odor threshold in comparison to 1,8‐cineole. The determination of odor qualities and odor thresholds was accomplished by gas chromatography/olfactometry (GC/O) on achiral and chiral GC capillaries. The results were correlated with common theories on structureodor relationships.
Gates and Binding Pockets for Nitric Oxide with Cytochrome c′, According to Molecular Dynamics
Authors: Pietra Francesco 
Published: October 2013

AbstractRandom‐acceleration molecular‐dynamics (RAMD) simulations with models of homodimeric 6‐ligated distal‐NO and 5‐ligated proximal‐NO cytochrome c′ complexes, in TIP3 H2O, showed two distinct, non‐intercommunicating worlds. In the framework of a long cavity formed by four protein helices with heme at one extremity, NO was observed to follow different pathways with the two complexes to reach the solvent. With the 6‐ligated complex, NO was observed to progress by exploiting protein internal channels created by thermal fluctuations, and be temporarily trapped into binding pockets before reaching the preferred gate at the heme end of the cavity. In contrast, with the 5‐ligated complex, NO was observed to surface the solvent‐exposed helix 7, up to a gate at the other extremity of the protein, only occasionally finding an earlier, direct way out toward the solvent. That only bulk NO gets involved in forming the 5‐ligated proximal‐NO complex is in agreement with previous experimental observations, while the occurrence of binding pockets suggests that also reservoir NO might play a role with the distal‐NO complex.
Efficient Ruthenium Nanocatalysts in Liquid–Liquid Biphasic Hydrogenation Catalysis: Towards a Supramolecular Control through a Sulfonated Diphosphine–Cyclodextrin Smart Combination
Authors: Guerrero Miguel , Coppel Yannick , Chau Nguyet Tran Thanh , Roucoux Alain , Denicourt‐Nowicki Audrey , Monflier Eric , Bricout Hervé , Lecante Pierre , Philippot Karine 
Published: October 2013

AbstractThe combination between a sulfonated diphosphine (L) and a cyclodextrin (CD) allowed the preparation of very stable water‐soluble ruthenium nanoparticles (RuNPs) that displayed pertinent catalytic performances in hydrogenation of unsaturated substrates with a supramolecular control effect of the cyclodextrin. For comparison purpose, the RuNPs were produced by hydrogenation of the organometallic [Ru(1,5‐cyclooctadiene)(1,3,5‐cyclooctatriene)] complex under mild conditions (3 bar H2; room temperature) and in the presence of L or a L/CD mixture as stabilizer leading to Ru/L and Ru/L/CD systems, respectively. The so‐obtained nanoparticles were fully characterized by complementary techniques. Interestingly, NMR investigations evidenced 1) the strong coordination of the sulfonated diphosphine ligand at the metallic surface and 2) in the presence of cyclodextrin, the formation of an inclusion complex between L and CD that modified the coordination mode of the diphosphine. The investigation of both RuNPs systems in biphasic hydrogenation of unsaturated substrates pointed out relevant differences in terms of reactivity, thus evidencing the influence of the supramolecular interaction at the metallic surface on the catalytic performances of the nanocatalysts. This work took advantage of the supramolecular properties of a cyclodextrin to modulate the surface reactivity of diphosphine‐stabilized ruthenium nanoparticles and may open new opportunities in the field of nanocatalysis.
Fixed‐Bed Multi‐Tubular Reactors for Oxidative Dehydrogenation in Ethylene Process
Authors: Fattahi M. , Kazemeini M. , Khorasheh F. , Darvishi A. , Rashidi A. M. 
Published: October 2013

AbstractAn industrial‐scale reactor for ethylene production was modeled using the oxidative dehydrogenation of ethane (ODHE) in a multi‐tubular reactor system, examining a variety of parameters affecting reactor performance. The model showed that a double‐bed multi‐tubular reactor with intermediate air injection scheme was superior to a single‐bed design, due to the increased ethylene selectivity while operating under lower oxygen partial pressures. The optimized reactor length for 100 % oxygen conversion was theoretically determined for both reactor designs. The use of a distributed oxygen feed with a limited number of injection points indicated a significant improvement on the reactor performance in terms of ethane conversion and ethylene selectivity. This concept also overcame the reactor runaway temperature problem and enabled operations over a wider range of conditions to obtain enhanced ethylene production.
Industrial Xylene/Ethylbenzene Isomerization Unit Using a Radial‐Flow Reactor and EUO‐Type Zeolite
Authors: Gonçalves J. C. , Rodrigues A. E. 
Published: October 2013

AbstractA mathematical model based on 34 days continuous operation of an industrial isomerization unit was developed. The unit involves a radial‐flow reactor with a catalyst capable of converting xylenes and ethylbenzene to mixed xylenes. The catalyst contains EU‐1 zeolite, platinum, and alumina as binder. Two reactions are considered, i.e., ethylbenzene isomerization and xylene isomerization. The rates are based on the Hougen‐Watson model according to the literature. An optimization procedure based on the trust‐region‐reflective algorithm was carried out in order to obtain new kinetic constants that minimize the difference between the actual and the calculated values. The standard error of the parameters estimated was calculated through the deleted‐one Jackknife method.
Multiply Nitrated High‐Energy Dense Oxidizers Derived from the Simple Amino Acid Glycine
Authors: Baumann Andreas , Erbacher Anna , Evangelisti Camilla , Klapötke Thomas M. , Krumm Burkhard , Rest Sebastian F. , Reynders Martin , Sproll Véronique 
Published: October 2013

AbstractVarious energetic polynitro esters, carbamates, and nitrocarbamates that were derived from the amino acid glycine were fully characterized by single‐crystal X‐ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Owing to their positive oxygen balance, the suitability of these compounds as potential oxidizers in energetic formulations was investigated and discussed. In addition, the heats of formation of the products were calculated by using the Gaussian 09 program package at the CBS‐4M level of theory. From these values and the calculated densities (from the X‐ray data), several detonation parameters, such as detonation pressure, velocity, energy, and temperature, were computed by using the EXPLO5 code. Furthermore, their sensitivities towards impact, friction, and electrostatic discharge were tested by using a drop hammer, a friction tester (both BAM certified), and a small‐scale electrical‐discharge device, respectively.
Luminescent Amphiphilic 2,6‐Bis(1,2,3‐triazol‐4‐yl)pyridinePlatinum(II) Complexes: Synthesis, Characterization, Electrochemical, Photophysical, and Langmuir–Blodgett Film‐Formation Studies
Authors: Li Yongguang , Zhao Le , Tam Anthony Yiu‐Yan , Wong Keith Man‐Chung , Wu Lixin , Yam Vivian Wing‐Wah 
Published: October 2013

AbstractA new series of platinum(II) complexes with tridentate ligands 2,6‐bis(1‐alkyl‐1,2,3‐triazol‐4‐yl)pyridine and 2,6‐bis(1‐aryl‐1,2,3‐triazol‐4‐yl)pyridine (N7R), [Pt(N7R)Cl]X (1–7) and [Pt(N7R)(CCR′)]X (8–17; R=n‐C4H9, n‐C8H17, n‐C12H25, n‐C14H29, n‐C18H37, C6H5, and CH2‐C6H5; R′=C6H5, C6H4‐CH3‐p, C6H4‐CF3‐p, C6H4‐N(CH3)2‐p, and cholesteryl 2‐propyn‐1‐yl carbonate; X=OTf−, PF6−, and Cl−), has been synthesized and characterized. Their electrochemical and photophysical properties have also been studied. Two amphiphilic platinum(II)2,6‐bis(1‐dodecyl‐1,2,3‐triazol‐4‐yl)pyridine complexes (3‐Cl and 8) were found to form stable and reproducible Langmuir–Blodgett (LB) films at the air/water interface. These LB films were characterized by the study of their surface‐pressure–molecular‐area (π–A) isotherms, XRD, and IR and polarized‐IR spectroscopy.
A Computational Study of the Mechanism of Hydrogen Evolution by Cobalt(Diimine‐Dioxime) Catalysts
Authors: Bhattacharjee Anirban , Andreiadis Eugen S. , Chavarot‐Kerlidou Murielle , Fontecave Marc , Field Martin J. , Artero Vincent 
Published: October 2013

AbstractCobalt(diimine‐dioxime) complexes catalyze hydrogen evolution with low overpotentials and remarkable stability. In this study, DFT calculations were used to investigate their catalytic mechanism, to demonstrate that the initial active state was a CoI complex and that H2 was evolved in a heterolytic manner through the protonation of a CoIIhydride intermediate. In addition, these catalysts were shown to adjust their electrocatalytic potential for hydrogen evolution to the pH value of the solution and such a property was assigned to the presence of a H+‐exchange site on the oxime bridge. It was possible to establish that protonation of the bridge was directly involved in the H2‐evolution mechanism through proton‐coupled electron‐transfer steps. A consistent mechanistic scheme is proposed that fits the experimentally determined electrocatalytic and electrochemical potentials of cobalt(diimine‐dioxime) complexes and reproduces the observed positive shift of the electrocatalytic potential with increasing acidity of the proton source.
DFT Study on the Recovery of Hoveyda–Grubbs‐Type Catalyst Precursors in Enyne and Diene Ring‐Closing Metathesis
Authors: Núñez‐Zarur Francisco , Solans‐Monfort Xavier , Pleixats Roser , Rodríguez‐Santiago Luis , Sodupe Mariona 
Published: October 2013

AbstractDFT (B3LYP‐D) calculations have been used to better understand the origin of the recovered Hoveyda–Grubbs derivative catalysts after ring‐closing diene or enyne metathesis reactions. For that, we have considered the activation process of five different Hoveyda–Grubbs precursors in the reaction with models of usual diene and enyne reactants as well as the potential precursor regeneration through the release/return mechanism. The results show that, regardless of the nature of the initial precursor, the activation process needs to overcome relatively high energy barriers, which is in agreement with a relatively slow process. The precursor regeneration process is in all cases exergonic and it presents low energy barriers, particularly when compared to those of the activation process. This indicates that the precursor regeneration should always be feasible, unlike the moderate recoveries sometimes observed experimentally, which suggests that other competitive processes that hinder recovery should take place. Indeed, calculations presented in this work show that the reactions between the more abundant olefinic products and the active carbenes usually require lower energy barriers than those that regenerate the initial precatalyst, which could prevent precursor regeneration. On the other hand, varying the precursor concentration with time obtained from the computed energy barriers shows that, under the reaction conditions, the precursor activation is incomplete, thereby suggesting that the origin of the recovered catalyst probably arises from incomplete precursor activation.