bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphometry of small recent impact craters on Mars: Size and terrain dependence, short‐term modification
Authors: Watters W. A. , Geiger L. M. , Fendrock M. , Gibson R.
Published: January 2015

Most recent studies of crater morphometry on Mars have addressed large craters (D>5 km) using elevation models derived from laser altimetry. In the present work, we examine a global population of small (25 m ≤D≤5 km), relatively well‐preserved simple impact craters using HiRISE stereo‐derived elevation models. We find that scaling laws from prior studies of large simple craters generally overestimate the depth and volume at small diameters. We show that crater rim curvature exhibits a strong diameter dependence that is well‐described by scaling laws for D<1 km. Above this diameter, upper rim slopes begin to exceed typical repose angles and crater rims sharpen significantly. This transition is likely the result of gravity‐driven collapse of the upper cavity walls during crater formation or short‐term modification. In addition, we identify a tendency for small craters (D<500m) to be more conical than large craters, and we show that the average cavity cross section is well‐described by a power law with exponent ∼1.75 (neither conical nor paraboloidal). We also conduct a statistical comparison of crater subpopulations to illuminate trends with increasing modification and target strength. These results have important implications for describing the “initial condition” of simple crater shape as a function of diameter and geological setting and for understanding how impact craters are modified on the Martian surface over time.
The Mechanical Behavior of ALD‐Polymer Hybrid Films Under Tensile Strain
Authors: Bulusu Anuradha , Graham Samuel , Bahre Hendrik , Behm Henrik , Böke Marc , Dahlmann Rainer , Hopmann Christian , Winter Jörg
Published: January 2015

Atomic layer deposition (ALD) is increasingly becoming commonplace to deposit high density, conformal films, as novel deposition techniques allow improved deposition rates on various substrates. Diffusion and miscibility of ALD precursors with polymers are known to affect film nucleation. To assess the influence of polymeric underlayer on the growth and mechanical behavior of ALD films, we deposited aluminum oxide (Al2O3) and titanium dioxide (TiO2) films on three different polymers with known reactivity to the ALD precursors and compared them to films on polyethylene terephthalate (PET). We present the trends in nucleation and penetration of the ALD films on the various polymers as well as the in situ mechanical behavior under tensile strain. X‐ray photoelectron spectroscopy (XPS) revealed that Cytop, a fluorinated polymer and polyethyleneimine ethoxylated (PEIE) delay the nucleation of Al2O3 and TiO2 films. Time‐of‐flight mass spectrometry (ToFSIMS) shows the extent of diffusion of the ALD precursors into the polymer underlayer, delaying nucleation. Tensile tests show that while the crack onset strain remained unchanged despite the various polymer underlayers, the crack saturation density decreased for ALD films on PEIE and polyhydroxystyrene (PHOST). Films on Cytop showed no crack saturation limit until the nucleation delay was overcome indicating that judicious choice of the ALD film and polymer underlayer will allow tailoring of the length of the diffusion zone and crack saturation, but not the crack onset strain, which will be addressed in future studies.
Transient response of two‐layer slot coating flows to periodic disturbances
Authors: Maza Danmer , Carvalho Marcio S.
Published: January 2015

Coating uniformity requirement is becoming more severe as new products come into the market. Coating processes have to be designed not only based on the steady‐state operation but also taking into account how the flow responds to ongoing disturbances on process conditions. These disturbances may lead to thickness variation on the deposited liquid layers that may be unacceptable for product performance. This study extends available transient analysis of single‐layer slot coating to determine the amplitude of the oscillation of each individual coated layer in two‐layer slot coating process in response to small periodic perturbation on different operating parameters. The predictions were obtained by solving the complete transient Navier–Stokes equations for free surface flows. The results show the most dangerous perturbations and how the deposited film thickness variations of each layer can be minimized by changing the geometry of the die lip and liquid viscosities. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1699–1707, 2015
Design und enantioselektive Synthese von Cashmeran‐Riechstoffen mithilfe der “Enol‐Katalyse”
Authors: Felker Irene , Pupo Gabriele , Kraft Philip , List Benjamin
Published: January 2015

Durch Überlagerungsanalysen wurden neue Cashmeran‐Riechstoffe entworfen, deren kurze Synthesen auf einer neuartigen Brønsted‐Säure‐katalysierten asymmetrischen Michael‐Addition von nichtaktivierten α‐substituierten Ketonen beruht. Dieser Schlüsselschritt wurde durch eine neue Art der Enol‐Aktivierungskatalyse realisiert, die unterschiedliche cyclische Ketone mit α‐quartären Stereozentrum in guten bis sehr guten Ausbeuten und mit hohen Enantioselektivitäten zugänglich macht. Die enantiomerenreinen Zielstrukturen wurden durch anschließende McMurry‐Kupplung und Saegusa‐Ito‐Oxidation hergestellt. Ein Enantiomer hat tatsächlich die typischen Geruchscharakteristika von Cashmeran.
Ratiometric Fluorescence Imaging of Cellular Polarity: Decrease in Mitochondrial Polarity in Cancer Cells
Authors: Jiang Na , Fan Jiangli , Xu Feng , Peng Xiaojun , Mu Huiying , Wang Jingyun , Xiong Xiaoqing
Published: January 2015

Mitochondrial polarity strongly influences the intracellular transportation of proteins and interactions between biomacromolecules. The first fluorescent probe capable of the ratiometric imaging of mitochondrial polarity is reported. The probe, termed BOB, has two absorption maxima (λabs=426 and 561 nm) and two emission maxima—a strong green emission (λem=467 nm) and a weak red emission (642 nm in methanol)—when excited at 405 nm. However, only the green emission is markedly sensitive to polarity changes, thus providing a ratiometric fluorescence response with a good linear relationship in both extensive and narrow ranges of solution polarity. BOB possesses high specificity to mitochondria (Rr=0.96) that is independent of the mitochondrial membrane potential. The mitochondrial polarity in cancer cells was found to be lower than that of normal cells by ratiometric fluorescence imaging with BOB. The difference in mitochondrial polarity might be used to distinguish cancer cells from normal cells.
Antibody Activation using DNA‐Based Logic Gates
Authors: Janssen Brian M. G. , van Rosmalen Martijn , van Beek Lotte , Merkx Maarten
Published: January 2015

Oligonucleotide‐based molecular circuits offer the exciting possibility to introduce autonomous signal processing in biomedicine, synthetic biology, and molecular diagnostics. Here we introduce bivalent peptide–DNA conjugates as generic, noncovalent, and easily applicable molecular locks that allow the control of antibody activity using toehold‐mediated strand displacement reactions. Employing yeast as a cellular model system, reversible control of antibody targeting is demonstrated with low nM concentrations of peptide–DNA locks and oligonucleotide displacer strands. Introduction of two different toehold strands on the peptide–DNA lock allowed signal integration of two different inputs, yielding logic OR‐ and AND‐gates. The range of molecular inputs could be further extended to protein‐based triggers by using protein‐binding aptamers.
Design and Enantioselective Synthesis of Cashmeran Odorants by Using “Enol Catalysis”
Authors: Felker Irene , Pupo Gabriele , Kraft Philip , List Benjamin
Published: January 2015

Novel Cashmeran odorants were designed by molecular modeling. Their short syntheses involve a novel asymmetric Brønsted acid catalyzed Michael addition of unactivated α‐substituted ketones. This key transformation was realized by utilizing a new type of enol activation catalysis and affords different cyclic ketones bearing α‐quaternary stereocenters in good to excellent yields and with high enantioselectivity. Subsequent McMurry coupling and Saegusa–Ito oxidation furnished the enantiopure target odorants, one enantiomer of which indeed possesses the typical olfactory aspects of Cashmeran.
Ba3P5N10Br:Eu2+: A Natural‐White‐Light Single Emitter with a Zeolite Structure Type
Authors: Marchuk Alexey , Schnick Wolfgang
Published: January 2015

Illumination sources based on phosphor‐converted light emitting diode (pcLED) technology are nowadays of great relevance. In particular, illumination‐grade pcLEDs are attracting increasing attention. Regarding this, the application of a single warm‐white‐emitting phosphor could be of great advantage. Herein, we report the synthesis of a novel nitridophosphate zeolite Ba3P5N10Br:Eu2+. Upon excitation by near‐UV light, natural‐white‐light luminescence was detected. The synthesis of Ba3P5N10Br:Eu2+ was carried out using the multianvil technique. The crystal structure of Ba3P5N10Br:Eu2+ was solved and refined by single‐crystal X‐ray diffraction analysis and confirmed by Rietveld refinement and FTIR spectroscopy. Furthermore, spectroscopic luminescence measurements were performed. Through the synthesis of Ba3P5N10Br:Eu2+, we have shown the great potential of nitridophosphate zeolites to serve as high‐performance luminescence materials.
Copper nanoparticles on dichromium trioxide: a highly efficient catalyst from copper chromium hydrotalcite for oxidant‐free dehydrogenation of alcohols
Authors: Zhu Yaoqin , Shen Mengnan , Xia Yonggen , Lu Ming
Published: January 2015

Stable copper(0) nanoparticles supported on chromium (Cu(0)/Cr2O3) are prepared from the composite precursor copper chromium hydrotalcite. The resulting Cu(0)/Cr2O3 catalyst is first used in the selective dehydrogenation of alcohols to aldehydes. More impressively, these dehydrogenations are performed without oxidants and yields of products are high. The stability of Cu(0)/Cr2O3 is also assessed by studying its recoverability and reusability for up to five cycles. Copyright © 2015 John Wiley & Sons, Ltd.
Mechanical characterization of high‐performance graphene oxide incorporated aligned fibroporous poly(carbonate urethane) membrane for potential biomedical applications
Authors: Thampi Sudhin , Muthuvijayan Vignesh , Parameswaran Ramesh
Published: January 2015

In this article, we report the development of graphene oxide (GO) reinforced electrospun poly(carbonate urethane) (PCU) nanocomposite membranes intended for biomedical applications. In this study, we aimed to improve the mechanical properties of PCU fibroporous electrospun membranes through fiber alignment and GO incorporation. Membranes with 1, 1.5, and 3% loadings of GO were evaluated for their morphology, mechanical properties, crystallinity, biocompatibility, and hemocompatibility. The mechanical properties were assessed under both static and dynamic conditions to explore the tensile characteristics and viscoelastic properties. The results show that GO presented a good dispersion and exfoliation in the PCU matrix, contributing to an increase in the mechanical performance. The static mechanical properties indicated a 55% increase in the tensile strength, a 127% increase in toughness for 1.5 wt % GO loading and the achievement of a maximum strength reinforcement efficiency value at the same loading. Crystallinity changes in membranes were examined by X‐ray diffraction analysis. In vitro cytotoxicity tests with L‐929 fibroblast cells and percentage hemolysis tests with fresh venous blood displayed the membranes to be cytocompatible with acceptable levels of hemolytic characteristics. Accordingly, these results highlight the potential of this mechanically improved composite membrane's application in the biomedical field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41809.
Improving properties of ceramic silicone rubber composites using high vinyl silicone oil
Authors: Cao Erping , Cui Xiaoqian , Wang Kai , Li Yinyin , Guo Weihong
Published: January 2015

Reactive high vinyl silicone oil (HVSO) was selected to prepare the ceramic silicone rubber composites. The effects of HVSO on the mechanical properties and thermal stabilities of ceramic silicone rubber composites were investigated. The structures of the cross‐linked network of silicone rubber with or without HVSO were studied. The intermolecular space of silicone rubber was enlarged, and the cross‐linked point was concentrated by addition of HVSO, which was demonstrated by cross‐linking densities, scanning electron microscope (SEM) images, and dynamic mechanical analysis (DMA). The cross‐linked network model was formed with the slipping of the cross‐linked points along with the silicone rubber chain. Mechanical properties of composites were enhanced by the formation of this cross‐linked network. The tear strength, tensile strength, and elongation at break of the composites were increased by 18.5%, 13.2%, and 37.4% by the adding of 2 phr HVSO, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41864.
Bioactive polymeric nanofiber matrices for skin regeneration
Authors: Guadalupe Eross , Ramos Daisy , Shelke Namdev B. , James Roshan , Gibney Christian , Kumbar Sangamesh G.
Published: January 2015

Electrospun nanofiber matrices have attracted a great deal of attention as matrices for skin repair and regeneration. The current manuscript reports the fabrication and characterization of a bioactive polycaprolactone (PCL) fiber matrix for its ability to deliver multiple factors. Bioactive PCL matrices were created by incorporating a model angiogenic factor and a model antibiotic drug. Chitosan coating on the fiber matrices significantly improved the ability to hold moisture and contributed to antibiotic activity. These fiber matrices have a modulus of 5.8 ± 1.3 MPa and matrices subjected to degradation over 4 weeks did not lose their tensile properties due to slow degradation rate. Chitosan coating avoided the initial burst release commonly associated with fiber matrices and only 60% of the encapsulated drug was released over a period of 15 days. Control PCL‐chitosan matrices were able to reduceStaphylococcus aureus(S. aureus) growth both in static and dynamic condition as compared to formulations with 50 mg gentamicin. In general, all the fiber matrices were able to support fibroblast growth and maintained normal cell morphology. Such bioactive bandages may serve as versatile and less expensive alternatives for the treatment of complex wounds. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 41879.
Swelling kinetics, mechanical properties, and release characteristics of chitosan‐based semi‐IPN hydrogels
Authors: Özbaş Zehra , Gürdağ Gülten
Published: January 2015

Two series of pH‐sensitive semi‐interpenetrating network hydrogels (semi‐IPN) based on chitosan (CS) natural polymer and acrylamide (AAm) and/or N‐hydroxymethyl acrylamide (HMA) monomers by varying the monomer and CS ratios were synthesized by free radical chain polymerization. 5‐Fluorouracil (5‐FU), a model anticancer drug, has been added to the feed composition before the polymerization. The characterization of gels indicated that the drug is molecularly dispersed in the polymer matrix. The swelling kinetics of drug‐loaded gels have decreased with increased HMA content at 37°C in both distilled water and buffer solutions with a pH of 2.1 or 7.4. Elastic modulus of the gels increased with the increase in HMA content and higher CS concentration enhanced the elastic modulus positively. Moreover, cumulative release percentages of the gels for 5‐FU were ca. 10% higher in pH 2.1 than those in pH 7.4 media. It was determined that they can be suitable for the use in both gastric and colon environments. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41886.
Extending the understanding of critical success factors for implementing business intelligence systems
Authors: Yeoh William , Popovič Aleš
Published: January 2015

Extant studies suggest implementing a business intelligence (BI) system is a costly, resource‐intensive and complex undertaking. Literature draws attention to the critical success factors (CSFs) for implementation of BI systems. Leveraging case studies of seven large organizations and blending them with Yeoh and Koronios's (2010) BI CSFs framework, our empirical study gives evidence to support this notion of CSFs and provides better contextual understanding of the CSFs in BI implementation domain. Cross‐case analysis suggests that organizational factors play the most crucial role in determining the success of a BI system implementation. Hence, BI stakeholders should prioritize on the organizational dimension ahead of other factors. Our findings allow BI stakeholders to holistically understand the CSFs and the associated contextual issues that impact on implementation of BI systems.
When are readership counts as useful as citation counts? Scopus versus Mendeley for LIS journals
Authors: Maflahi Nabeil , Thelwall Mike
Published: January 2015

In theory, articles can attract readers on the social reference sharing site Mendeley before they can attract citations, so Mendeley altmetrics could provide early indications of article impact. This article investigates the influence of time on the number of Mendeley readers of an article through a theoretical discussion and an investigation into the relationship between counts of readers of, and citations to, 4 general library and information science (LIS) journals. For this discipline, it takes about 7 years for articles to attract as many Scopus citations as Mendeley readers, and after this the Spearman correlation between readers and citers is stable at about 0.6 for all years. This suggests that Mendeley readership counts may be useful impact indicators for both newer and older articles. The lack of dates for individual Mendeley article readers and an unknown bias toward more recent articles mean that readership data should be normalized individually by year, however, before making any comparisons between articles published in different years.
Which of the world's institutions employ the most highly cited researchers? An analysis of the data from highlycited.com
Authors: Bornmann Lutz , Bauer Johann
Published: January 2015

In 2014, Thomson Reuters published a list of the most highly cited researchers worldwide (highlycited.com). Because the data are freely available for downloading and include the names of the researchers' institutions, we produced a ranking of the institutions on the basis of the number of highly cited researchers per institution. This ranking is intended to be a helpful amendment of other available institutional rankings.
The operationalization of “fields” as WoS subject categories (WCs) in evaluative bibliometrics: The cases of “library and information science” and “science & technology studies”
Authors: Leydesdorff Loet , Bornmann Lutz
Published: January 2015

Normalization of citation scores using reference sets based on Web of Science subject categories (WCs) has become an established (“best”) practice in evaluative bibliometrics. For example, the Times Higher Education World University Rankings are, among other things, based on this operationalization. However, WCs were developed decades ago for the purpose of information retrieval and evolved incrementally with the database; the classification is machine‐based and partially manually corrected. Using the WC “information science & library science” and the WCs attributed to journals in the field of “science and technology studies,” we show that WCs do not provide sufficient analytical clarity to carry bibliometric normalization in evaluation practices because of “indexer effects.” Can the compliance with “best practices” be replaced with an ambition to develop “best possible practices”? New research questions can then be envisaged.
Bemessungsdiagramme für den biegebeanspruchten Stab im Holzbau
Authors: Moosbrugger Thomas , Krenn Harald , Bogensperger Thomas
Published: January 2015

Im vorliegenden Aufsatz werden Bemessungstafeln zur Vorbemessung von Bauteilen aus Holz – Ermittlung der erforderlichen Querschnittshöhe – in Abhängigkeit definierter Eingangsparameter (Einwirkungen, Geometrie, Systemdefinitionen, Materialeigenschaften) vorgestellt. Eine allgemeingültige Aussage, welcher ULS‐ bzw. SLS‐Nachweis die relevante Bemessungssituation für die Dimensionierung eines Bauteiles widerspiegelt, kann aufgrund der Vielzahl an Einflussparametern, wie z. B. der Materialkennwerte, der Trägerspannweite und der Belastung, a priori nicht eindeutig getätigt werden. Für die effiziente Vorbemessung gemäß ÖNORM EN 1995‐1‐1 [1] liegen bis dato keinerlei nutzbare Bemessungsdiagramme für biegebeanspruchte Stäbe mit wissenschaftlicher Aussagekraft vor.

Design charts for a single spanned timber beam under bending – Part 1: Roof beam with a homogeneous rectangular beam cross‐section

In the presented paper design charts for the preliminary design of components made of timber (determination of the required cross‐sectional height) are shown. The charts are given as functions of several defined input parameters like loads, system geometry and material behavior. A generally valid statement, which kind of verification (ULS or SLS) reflects the relevant design situation for the design of a timber component is not possible. This may occur due to numerous influencing parameters. Currently no design charts for the efficient preliminary design according to ÖNORM EN 1995‐1‐1 [1] are available.
Buchenfurnierschichtholz für Fachwerkträger und verstärktes Brettschichtholz
Authors: Enders‐Comberg Markus , Frese Matthias , Blaß Hans Joachim
Published: January 2015

Mit Buchenfurnierschichtholz (Buchen‐FSH) gibt es für den Ingenieurholzbau seit einem Jahr einen neuen Holzwerkstoff. In Abhängigkeit von der Ausrichtung der Schälfurniere in der geschichteten Struktur sind charakteristische Zugfestigkeiten von bis zu 70 N/mm2 in Haupt‐ und bis zu 17 N/mm2 in Querrichtung bauaufsichtlich festgelegt. Ein Material mit diesen Festigkeitswerten eröffnet neue konstruktive Möglichkeiten. Der Aufsatz berichtet über gezielte Untersuchungen an Anschlüssen für Fachwerkträger aus Buchen‐FSH und Verstärkungen von Fichtenbrettschichtholz mit keilgezinkten Lamellen aus Buchen‐FSH. Die Ergebnisse zeigen, dass bei Fachwerkträgern die überdurchschnittlich hohen Materialfestigkeiten aufgrund der limitierenden Wirkung von Anschlusstragfähigkeiten fallweise nicht voll ausgenutzt werden können. Es bleibt Raum für die Entwicklung von leistungsfähigen FSH‐spezifischen Anschlusslösungen. In der Funktion als Verstärkung für Brettschichtholz können Buchen‐FSH‐Lamellen zu einer signifikanten Steigerung der Biegefestigkeit beitragen. Experimentelle Nachweise hierzu stehen noch aus.

Beech LVL for trusses and reinforced glulam

Beech LVL is an engineered wood product for timber structures; it is available for one year. Depending on the orientation of the veneers in the material, characteristic tensile strengths of up to 70 N/mm2 in main and 17 N/mm2 in transversal direction are defined in the corresponding technical approval. A material having such strength properties opens new structural possibilities. The paper reports purposive investigations on joints for truss girders made of beech LVL and on glulam reinforcements made of finger jointed beech LVL laminations. Regarding truss girders, the results demonstrate that the high material strengths cannot always be used due to the limiting effect of the joint capacities. Hence, opportunities remain for the development of efficient LVL specific joint solutions. Beech LVL laminations as glulam reinforcement may contribute to a significant strength increase. However, corresponding experimental verifications are still pending.
Kunstharzpressholz zur Verstärkung von Brettschichtholz
Authors: Haller Peer , Heiduschke Andreas , Putzger Robert , Hartig Jens
Published: January 2015

Es wurden Biegeträger aus Brettschichtholz (BSH) untersucht, die zur Erhöhung der Tragfähigkeit und der Dauerhaftigkeit auf der Zug‐ und wahlweise auf der Druckseite mit Kunstharzpressholz (KHP) verstärkt wurden. KHP ist ein Holzwerkstoff, der aus phenolharzgetränkten Furnieren der Rotbuche (Fagus sylvatica) besteht. KHP weist einen Elastizitätsmodul von über 20000 N/mm2 und eine Biegefestigkeit von 200 N/mm2 auf, was gegenüber den entsprechenden Werten von BSH GL24h eine Verdopplung bzw. Verdreifachung bedeutet. Die Verstärkung von Biegeträgern aus GL24h erbrachte bei sonst gleichen Querschnitten mehr als eine Verdopplung der Tragfähigkeit; die Steifigkeit erhöhte sich um etwa ein Drittel. Außerdem wurde der Verbund zwischen BSH und KHP abwechselnd befeuchtet und getrocknet, um die Dauerhaftigkeit zu testen. Teilweise getränktes KHP nahm viel Feuchtigkeit auf und quoll stark, jedoch weniger als unbehandelte Rotbuche. Dieser Werkstoff ist daher nur für die Nutzungsklassen 1 und 2 geeignet. Vollständig getränktes KHP hingegen nahm kaum Feuchtigkeit auf und quoll nur wenig, sodass es sich ebenso für die Nutzungsklasse 3 empfiehlt.

Compressed laminated wood for the strengthening of glued laminated timber

Glued laminated timber girders were investigated, which were strengthened with compressed laminated wood at the tension lamella and optionally also at the compression lamella to increase load‐bearing capacity and stiffness. Compressed laminated wood is a wood composite consisting of beech (Fagus sylvatica) veneers, which are impregnated with phenol‐resorcin resin. Compressed laminated wood possesses a YOUNG's modulus of more than 20000 N/mm2 and a bending strength of more than 200 N/mm2, which is compared to glued laminated timber GL24h a doubling and a tripling, respectively. The strengthening of the GL24h girders with compressed laminated wood led to a doubling of the bending capacity and to an increase of stiffness of about one third compared to plain GL24h girders with the same cross section. Moreover, the joint of glued laminated timber and compressed laminated wood was exposed to wetting‐drying cycles to investigate the durability. Partly impregnated compressed laminated wood absorbed a lot of moisture and swelled heavily, but still less than plain beech wood. Thus, this material is only recommendable for the service classes 1 and 2. Completely impregnated compressed laminated wood showed only very low moisture uptake and swelling and can be applied also in service class 3.
Formholzrohre aus Buche
Authors: Haller Peer , Hartig Jens , Wehsener Jörg
Published: January 2015

Die tragende Verwendung der Buche (Fagus sylvatica) wird gegenwärtig in den deutschsprachigen Ländern intensiv erforscht. Der Grund dafür ist der große, weitgehend ungenutzte Buchenbestand, der im Zuge des Waldumbaus zu Lasten der Fichte (Picea abies) weiter wachsen wird. Heute hängt die Wertschöpfungskette der Forst‐ und Holzwirtschaft zu 90 % am Nadelbaum. Fast zwei Drittel davon entfallen auf den Bau. Die Struktur der Wälder wird sich in Zukunft ändern und die Industrie vor die Aufgabe stellen, der Ressourcenveränderung mit neuen Verfahren und Produkten zu begegnen. Ein Beispiel dafür ist das Formholzrohr. Dieser Beitrag untersucht das Tragverhalten solcher Rohre, die nach einem speziellen Verfahren aus massiven Platten gerollt wurden.

Molded wooden tubes made of beech

The structural use of beech (Fagus sylvatica) is currently under intensive investigation in the German‐speaking countries. The reason is the large, widely unused stock in the forests, which will further increase at the burden of spruce (Picea abies) due to the forest conversion. Today, the value added chain of the forest and timber economy depends to 90 % on softwood. Almost two third thereof are used for the building industry. The structure of the forests will change in the future and it is the task of the industry to react with new methods and products. An example is the molded wooden tube. This contribution investigates the load‐bearing behavior of such tubes, which are rolled out of massive timber board following a special technique.
Mindestnutzhöhen von Stahlbetonplatten für l/250 und l/500
Authors: Jeromin Wolf
Published: January 2015

Die statische Nutzhöhe und damit die Querschnittshöhe wird bei Stahlbetonplatten durch Begrenzung der Bauteildurchbiegung bestimmt. Diese Begrenzung ist zur Vermeidung von Schäden infolge zu großen Deckendurchhangs oder in nicht tragenden Wänden erforderlich. Sie erfolgt durch geometrische Kriterien (zulässige Biegeschlankheiten) ohne direkte Berechnung. Sie sind in DIN 1045‐1 [1] und Eurocode 2 [2] unterschiedlich groß angegeben und erfüllen die dort ebenfalls als Grenzwerte angegebenen Durchbiegungswerte von l/250 und l/500 nicht. Überdies werden zweiachsig gespannte Platten trotz deutlich geringerer Beanspruchung hinsichtlich der Biegeschlankheit wie einachsig gespannte behandelt. Um diese Differenzen aufzuheben, werden für die Durchbiegungswerte von l/250 und l/500 ein Lösungsweg, Gleichungen für die Nutzhöhe und Diagramme vorgestellt, die für ein‐ und zweiachsige Tragwirkung für starre und elastische Linienlagerung sowie Punktstützung gelten.

Minimum useful heights of reinforced concrete for l/250 and l/500

The static useful height and hence the cross‐sectional height of reinforced concrete slabs is determined by limiting the component sag. This restriction is necessary in order to prevent damage due to excessive sagging of the floor or in non‐constructional walls. It is based on geometrical criteria (permitted flexural slenderness values) without direct calculation. The values stated in DIN 1045‐1 [1] and Eurocode 2 [2] are of different magnitudes and do not comply with the limit values of l/250 and l/500 which are likewise stipulated there for the sag. Moreover, despite their distinctly lower stress and strain, slabs with biaxial stress are treated in the same way as slabs with uniaxial stress where flexural slenderness is concerned. To eliminate these differences, a suitable solution is presented for a sag of l/250 and l/500, with equations for useful heights and diagrams which are valid for both rigid and elastic linear support as well as point support in uniaxial and biaxial structural conditions.
Einfluss der Nachbehandlung auf das Karbonatisierungsverhalten von Beton aus klinkerarmen Zementen
Authors: Hainer Stefan , Proske Tilo , Graubner Carl‐Alexander
Published: January 2015

Die Dauerhaftigkeit von Betonbauteilen wird wesentlich durch die Nachbehandlung beeinflusst. Die erforderliche Nachbehandlungsdauer von Betonbauteilen ist normativ durch die Expositionsklasse und die Festigkeitsentwicklung des Betons determiniert. Der vorliegende Beitrag befasst sich mit dem Einfluss der Nachbehandlung auf die Druckfestigkeit und die Karbonatisierungstiefe von Betonen aus Zementen mit niedrigem Klinkergehalt.

Im Rahmen experimenteller Untersuchungen wurden sowohl der Einfluss der Nachbehandlungsdauer als auch die Auswirkungen variierender Umgebungsbedingungen und einer nachträglichen Befeuchtung auf die Betoneigenschaften analysiert. Weiterhin erfolgte ein Vergleich der Versuchsergebnisse mit bekannten Vorhersagemodellen zum Einfluss der Nachbehandlungsdauer sowie der Umgebungsbedingungen auf die Karbonatisierungstiefe. Abschließend wird eine Bewertung der in DIN 1045‐3 [1] festgelegten Mindestdauer der Nachbehandlung vorgenommen.

Influence of curing on the carbonation of clinker‐reduced concretes

The durability of concrete structures is significantly influenced by the curing conditions. The normative required curing time of concrete elements is determined by the exposure class and the strength development of the concrete. This article deals with the influence of curing on the compressive strength and the carbonation depth of concretes with low clinker cements.

As part of the experimental investigations, both the influence of the curing time and the effects of varying environmental conditions and a subsequent moistening on the concrete properties were analyzed. Furthermore, a comparison of the results with known prediction models on the influence of curing time and environmental conditions on the carbonation depth was carried out. Subsequently an evaluation of the required minimum curing time according to DIN 1045‐3 [1] was conducted.
Hochduktiler Beton mit Kurzfaserbewehrung
Authors: Mechtcherine Viktor
Published: January 2015

Hochduktile Betone mit Kurzfaserbewehrung (meist Polyvinilalkohol‐ oder hochmodulige Polyethylenmikrofaser) sind neue zementgebundene Hochleistungswerkstoffe, die unter Zugbeanspruchung eine Verfestigung aufweisen und eine im Vergleich zu gebräuchlichen Faserbetonen mehr als einhundertmal höhere Bruchdehnung besitzen. Neben ihrer großen Verformungsfähigkeit sowie hohen Biegezug‐ und Schubfestigkeit weisen hochduktile Betone bis zur Bruchdehnung sehr geringe Rissöffnungen auf. Diese besonderen Eigenschaften machen diese neue Betonart für spezielle Anwendungen sowohl bei Neubau als auch bei Verstärkung und Instandsetzung von bestehenden Bauwerken interessant. Dieser Aufsatz gibt einen Überblick über die baustofflichen Grundlagen, die Eigenschaften und Anwendungsmöglichkeiten der neuen Faserbetonart.

Strain‐hardening cement‐based compositesMaterial design, properties and applications in construction

Strain‐hardening cement‐based composites (SHCC) are new, high‐performance materials reinforced in most cases with either polyvinyl‐alcohol or high‐density polyethylene fibre. These composites exhibit strain‐hardening behaviour under tensile loading. They have a strain capacity on an order of magnitude of more than one hundred times that of ordinary fibre‐reinforced concrete. SHCC have relatively high tensile and shear strengths and up until reaching strain capacity yield only very narrow, multiple cracks. These specific features make this new type of concrete attractive for a number of practical applications both in new construction and in the repair and strengthening of existing structures. The article at hand provides an overview of SHCCs' material design as well as of their mechanical performance, durability and fields of application.
Untersuchungen zur Alkali‐Kieselsäure‐Reaktion in vorgeschädigten Fahrbahndeckenbetonen
Authors: Giebson Colin , Voland Katja , Ludwig Horst‐Michael , Meng Birgit
Published: January 2015

In Betonbauteilen unter gleichzeitiger zyklischer Beanspruchung und externer Alkalizufuhr ist die Gefahr von Schäden infolge oder unter Mitwirkung einer Alkali‐Kieselsäure‐Reaktion (AKR) besonders hoch. Dies betrifft insbesondere Fahrbahndecken, bedingt durch den zunehmenden Schwerlastverkehr und den winterlichen Auftrag des Enteisungsmittels NaCl. Speziell die Rolle einer mechanischen Vorschädigung des Betons infolge der Verkehrsbeanspruchungen auf den Ablauf einer AKR ist dabei aber noch nicht in ausreichendem Umfang geklärt. Ein Teil der dazu seit 2012 durchgeführten Untersuchungen im Rahmen der DFG‐Forschergruppe 1498 soll im Folgenden vorgestellt werden. Es zeigte sich, dass eine AKR in definiert mechanisch vorgeschädigten Betonprobekörpern mit alkalireaktiven Gesteinskörnungen und unter äußerer Alkalizufuhr vor allem früher beginnt als in äquivalenten Probekörpern ohne Vorschädigung. Grund dafür ist das schnellere und tiefere Eindringen von Wasser und insbesondere gelöstem NaCl in den Beton, wodurch Na‐Ionen als Reaktionspartner für eine AKR früher und langfristig auch in größerer Menge verfügbar sind.

Investigations into alkali‐silica reaction in pre‐damaged pavement concretes

In concrete elements, simultaneously subjected to cyclic loadings and external alkalis, the risk for damages caused by or under participation of an alkali‐silica reaction (ASR) is particularly high. This concerns especially concrete pavements due to the increasing heavy load traffic and the wintry application of NaCl deicer. Notably the role of a mechanical pre‐damage of concrete caused by traffic loadings on the course of the ASR is largely unclear. A part of the investigations that has been conducted since 2012 into this issue within the scope of the DFG (German research foundation) funded research group 1498 shall be introduced in the following. It was evident that an ASR in defined mechanically pre‐damaged concrete prisms with alkali‐reactive aggregates and under an external supply of alkalis started earlier than in equal prisms without a pre‐damage. The reason for this is the faster and deeper ingress of water and particularly of dissolved NaCl into the concrete, by what Na ions as reaction partner for an ASR are available earlier and, in the long‐term, in greater amounts too.
Selective Separation of Toluene/n‐Heptane by Supported Ionic Liquid Membranes with [Bmim][BF4]
Authors: Zhang Fan , Feng Hao , Sun Wei , Zhang Weidong , Liu Junteng , Ren Zhongqi
Published: January 2015

Room‐temperature ionic liquids serve as alternative solvents for volatile organic compounds in liquid‐liquid extraction and liquid membrane separation. 1‐Butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF4]) was applied for extraction and supported ionic liquid membranes (SILMs) to separate toluene and n‐heptane. A high separation factor of toluene was achieved due to the strong interaction between ionic liquid cations and toluene. The mass transfer performance of the SILM process was enhanced by higher operating temperature. With the increase of initial toluene concentration in the feed phase, the mass transfer flux and removal efficiency of the SILM process were improved, while the separation factor decreased. The mass transfer flux was growing with the increase of flow rate at both sides. The SILM process was stable over a long time period due to the high viscosity and low volatility of [Bmim][BF4].
Study of an Annular Photoreactor with Tangential Inlet and Outlet: I. Fluid Dynamics
Authors: Peres José Carlos G. , Silvio Uirá de , Teixeira Antonio Carlos S. C. , Guardani Roberto , Jr. Ardson dos S. Vianna
Published: January 2015

Photochemical reactors tend to exhibit turbulent flow even with low Reynolds numbers. The k‐ϵ model is not always appropriate in this situation. An annular photoreactor was designed with tangential inlet and outlet tubes to investigate this. The fluid flow was characterized by residence time distribution (RTD) experiments, which were reproduced by computational fluid dynamics considering four relevant turbulence models: the k‐ϵ, the k‐ω, the shear stress transport, and the Reynolds stress models. Inlet effects induced helical flow throughout the reactor, switching to plug flow depending on the flow rate and the turbulence model. The k‐ω model properly deals with viscous effects and reproduces the experimental RTD curves with correlation coefficients greater than 0.9566, against 0.8705 from the k‐ϵ model.
Enantioselective Organocatalytic Reduction of β‐Trifluoromethyl Nitroalkenes: An Efficient Strategy for the Synthesis of Chiral β‐Trifluoromethyl Amines
Authors: Massolo Elisabetta , Benaglia Maurizio , Orlandi Manuel , Rossi Sergio , Celentano Giuseppe
Published: January 2015

An efficient organocatalytic stereoselective reduction of β‐trifluoromethyl‐substituted nitroalkenes, mediated by 3,5‐dicarboxylic ester‐dihydropyridines (Hantzsch ester type), has been successfully developed. A multifunctional thiourea‐based (S)‐valine derivative was found to be the catalyst of choice, promoting the reaction in up to 97 % ee. The methodology has been applied to a wide variety of substrates, leading to the formation of differently substituted precursors of enantiomerically enriched β‐trifluoromethyl amines. The mechanism of the reaction and the mode of action of the metal‐free catalytic species were computationally investigated; on the basis of DFT transition‐state (TS) analysis, a model of stereoselection was also proposed.
Polypyrrole Shell@3D‐Ni Metal Core Structured Electrodes for High‐Performance Supercapacitors
Authors: Chen Gao‐Feng , Su Yu‐Zhi , Kuang Pan‐Yong , Liu Zhao‐Qing , Chen Dao‐Yi , Wu Xu , Li Nan , Qiao Shi‐Zhang
Published: January 2015

Three‐dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high‐performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D‐Ni‐core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as‐prepared material exhibits a high specific capacitance (726 F g−1 at a charge/discharge rate of 1 A g−1), good rate capability (a decay of 33 % in Csp with charge/discharge rates increasing from 1 to 20 A g−1), and high cycle stability (only a small decrease of 4.2 % in Csp after 1000 cycles at a scan rate of 100 mV s−1). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as‐prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg−1) and superior long‐term cycle ability (only 4.4 % and 18.6 % loss in Csp after 2000 and 5000 cycles, respectively).
ChemInform Abstract: First‐Principles Screening of Complex Transition Metal Hydrides for High Temperature Applications.
Authors: Nicholson Kelly M. , Sholl David S.
Published: January 2015

Semi‐automated thermodynamic and phase diagram calculations based on DFT and grand canonical linear programming (GCLP) methods are used to screen 102 ternary and quaternary complex transition metal hydrides (CTMHs) and 26 ternary saline hydrides in a library of over 260 metals, intermetallics, binary, and higher hydrides to identify materials that release H2 at higher temperatures than the associated binary hydrides and at elevated temperatures (T < 1000 K, 1 bar H2 overpressure).
ChemInform Abstract: New Polymorphs of RE2FeSe2O2 (RE: La, Ce).
Authors: Nitsche Fabian , Niklaus Robin , Johrendt Dirk
Published: January 2015

Small crystals of the title compounds suitable for single crystal XRD are prepared from mixtures of rare‐earth metal oxide, rare‐earth metal, iron, and selenium powder using a eutectic mixture of NaI/KI as a flux (800—1100 °C, 5 d).
ChemInform Abstract: Enhancement of Solar Hydrogen Evolution from Water by Surface Modification with CdS and TiO2 on Porous CuInS2 Photocathodes Prepared by an Electrodeposition—Sulfurization Method.
Authors: Domen Kazunari , et al. et al.
Published: January 2015

A porous CuInS2 photoelectrode is prepared by sulfurization of an electrodeposited Cu—In metal precursor and surface modification with thin layers of CdS and TiO2.
ChemInform Abstract: Synthesis of Titanium Fluorophosphates and Fluorosulfates from Hexafluorotitanic Acid.
Authors: Marshall Kayleigh L. , Weller Mark T.
Published: January 2015

The new titanium fluoro‐compounds (III)—(VI) are obtained hydrothermally under high fluoride concentrations and their structures are determined by single crystal XRD.
ChemInform Abstract: Origin and Location of Electrons and Protons During the Formation of Intermetalloid Clusters [Sm@Ga3‐xH3‐2xBi10+x]3‐ (x = 0, 1).
Authors: Weinert Bastian , Mueller Fabian , Harms Klaus , Clerac Rodolphe , Dehnen Stefanie
Published: January 2015

[K([2.2.2]crypt)]3 [Sm@Ga2HBi11]0.9 [Sm@Ga3H3Bi10] 0.1·en·tol is synthesized from a mixture of [K([2.2.2]crypt)]2[GaBi3]·en and Sm(C5Me4H)3 in en (3 h in the dark) followed by layering with toluene (4 °C, 3 d, 10% yield).
ChemInform Abstract: Asymmetric Synthesis of α‐Branched Amines via Rh(III)‐Catalyzed C—H Bond Functionalization.
Authors: Wangweerawong Apiwat , Bergman Robert G. , Ellman Jonathan A.
Published: January 2015

The asymmetric addition of non‐acidic C—H bonds to imines is reported for the first time.
ChemInform Abstract: One‐Pot Synthesis of 12H‐Benzo[b]xanthen‐12‐ones and Naphtha[2,3‐b]furans from Non‐naphthalene Substrates.
Authors: He Yan , Guo Shenghai , Fan Xuesen , Guo Chenhao , Zhang Xinying
Published: January 2015

Oxidant‐initiated and base‐promoted tandem reaction of aldehyde substrates (I) and (III) allows the synthesis of benzoxanthenone derivatives.
ChemInform Abstract: Iron‐Catalyzed Efficient Intermolecular Amination of C(sp3)—H Bonds with Bromamine‐T as Nitrene Source.
Authors: Wang Haiyu , Li Yuxi , Wang Zhiming , Lou Jun , Xiao Yuling , Qiu Guofu , Hu Xianming , Altenbach Hans‐Josef , Liu Peng
Published: January 2015

As sole by product NaBr is formed.
ChemInform Abstract: Preparation, Characterization and Application of Silica‐Supported Palladium Complex as a New and Heterogeneous Catalyst for Suzuki and Sonogashira Reactions.
Authors: Ghiaci Mehran , Zarghani Monireh , Moeinpour Farid , Khojastehnezhad Amir
Published: January 2015

The new heterogeneous catalyst is effective in the title reactions including various aryl halide derivatives.
ChemInform Abstract: Protic Ionic Liquid [TMG][Ac] as an Efficient, Homogeneous and Recyclable Catalyst for One‐Pot Four‐Component Synthesis of 2H‐Indazolo[2,1‐b]phthalazine‐triones and Dihydro‐1H‐pyrano[2,3‐c]pyrazol‐6‐ones.
Authors: Veisi Hojat , Manesh Abbas Amini , Khankhani Narges , Ghorbani‐Vaghei Ramin
Published: January 2015

The applied catalyst can be recycled at least four times.
ChemInform Abstract: High‐Yield Formation of Substituted Tetracyanobutadienes (III) from Reaction of Ynamides (I) with Tetracyanoethylene
Authors: Betou Marie , Kerisit Nicolas , Meledje Esme , Leroux Yann R. , Katan Claudine , Halet Jean‐Francois , Guillemin Jean‐Claude , Trolez Yann
Published: January 2015

13 examples
ChemInform Abstract: Silver‐Catalyzed Functionalization of Esters by Carbene Transfer: The Role of Ylide Zwitterionic Intermediates.
Authors: Gava Riccardo , Fuentes M. Angeles , Besora Maria , Belderrain Tomas R. , Jacob Kane , Masera Feliu , Etienne Michel , Caballero Ana , Perez Pedro J.
Published: January 2015

A novel carbene transfer reaction from diazoesters to carboxylic acids is developed using a highly fluorinated tris(indazolyl)borate silver complex as catalyst.
ChemInform Abstract: Ethoxide‐Mediated Condensation of γ‐tert‐Butylallenoate and Aldehydes: Facile Stereoselective Synthesis of Conjugated Dienes and Enynes.
Authors: Xu Silong , Wang Liyi , Tang Yuhai , He Zhengjie
Published: January 2015

Condensation of aldehydes (II) with allenoate (I) in the presence of sodium ethoxide (III) affords dienes (IV) with exclusive E,E‐selectivity.
ChemInform Abstract: Copper‐Mediated ortho‐Nitration of (Hetero)Arenecarboxylates.
Authors: Katayev Dmitry , Pfister Kai F. , Wendling Timo , Goossen Lukas J.
Published: January 2015

An efficient chelation assisted regioselective C‐H nitration of a variety of arenes and hetero arenes is developed.
ChemInform Abstract: PdCu Nanoparticles Supported on Graphene: An Efficient and Recyclable Catalyst for Reduction of Nitroarenes.
Authors: Feng Yi‐Si , Ma Jing‐Jing , Kang Yu‐Mei , Xu Hua‐Jian
Published: January 2015

The catalyst is recycled and reused in five additional catalytic cycles without loss of activity.
ChemInform Abstract: Lewis Base Mediated Halogenation/Semipinacol Rearrangement of Diazo Compounds: New Access to α‐Halo‐quaternary Ketones.
Authors: Mao Haibin , Tang Zhongkai , Hu Hongwen , Cheng Yixiang , Zheng Wen‐Hua , Zhu Chengjian
Published: January 2015

The title reaction provides new access to α‐halo‐quaternary ketones via the carbon‐chain extension or ring expansion of ketones.
ChemInform Abstract: Exploring Bis(cyclometalated) Ruthenium(II) Complexes as Active Catalyst Precursors: Room‐Temperature Alkene‐Alkyne Coupling for 1,3‐Diene Synthesis.
Authors: Zhang Jing , Ugrinov Angel , Zhang Yong , Zhao Pinjing
Published: January 2015

A novel type of bis(cyclometalated) ruthenium(II) complexes is developed to promote the efficient coupling of internal alkynes with acrylates to give 1,3‐dienes in good yields.
ChemInform Abstract: Facile Access to Amides and Hydroxamic Acids Directly from Nitroarenes.
Authors: Jain Shreyans K. , Aravinda Kumar K. A. , Bharate Sandip B. , Vishwakarma Ram A.
Published: January 2015

With AcOH in CHCl3 amides are obtained as only products, whereas the use of KOH gives predominantly the corresponding hydroxamic acid.