bluuebunny/crossref_metadata_2025_split huggingface dataset:
Großbrände in Stahlbeton‐Straßentunneln
Authors: Schmidt Jörg , Bergerhausen Ulrich , Dehn Frank 
Published: October 2013

AbstractTunnel sind bedeutende Infrastrukturbauwerke. Die Beurteilung der Folgen von Brandereignissen in Tunneln ist daher auch von außerordentlicher volkswirtschaftlicher Bedeutung. Ein solches Brandereignis stellt z.B. der Brand eines mit Benzin beladenen Tanklastzugs dar. Im Rahmen eines Forschungsvorhabens für die Bundesanstalt für Straßenwesen (BASt) wurden verschiedene Szenarien für diesen Extremfall mit unterschiedlichen Energiefreisetzungsraten und deren Einfluss auf die Tunneltragsicherheit mittels numerischer Strömungssimulationen und Finite‐Elemente‐Berechnungen untersucht. Es konnte gezeigt werden, dass selbst Brandszenarien mit Flüssigkeitslachenbränden von bis zu 28 t Benzin durch die ZTV‐ING‐Temperatur‐Zeit‐Kurve abgedeckt werden können. Der folgende Beitrag fasst die wesentlichsten Ergebnisse zusammen.Fires in reinforced concrete road tunnels – temperature loads, temperature distribution and concrete spallingTunnels are important infrastructure constructions. The assessment of the effects of fire events is therefore also of major economic importance. The fire of a tank truck loaded with gasoline represents such a fire event. Part of a research project for the Federal Highway Research Institute (BASt) examined different scenarios for an extreme case, different rates of energy release and their influence on the tunnel safety by means of CFD and FEM simulations. It could be shown that even fire scenarios with liquid laugh burns up to 28t petrol can be covered by the ZTV‐ING temperature time curve. The following article summarizes the most important results.
Textilbeton – Grundlegende Untersuchungen im Überblick
Authors: Lorenz Enrico , Schütze Elisabeth , Schladitz Frank , Curbach Manfred 
Published: October 2013

AbstractMit der zunehmenden Verbreitung des Textilbetons wird die Standardisierung von Versuchen zur Ermittlung der Materialkennwerte immer bedeutsamer. Im Rahmen der Grundlagenforschung sowie in Praxisprojekten und Verfahren zur Erteilung zahlreicher Zustimmungen im Einzelfall (ZiE) bzw. zur Erlangung einer allgemeinen bauaufsichtlichen Zulassung (abZ) haben sich wesentliche Kennwerte inklusive der zugehörigen experimentellen Untersuchungen herauskristallisiert. Die Veröffentlichung gibt hierzu einen aktuellen Überblick.Textile Reinforced Concrete – Overview of standard test methodsDue to the fact that textile reinforced concrete is applied increasingly often, the development of standardized testing methods for the determination of material data is steadily gaining importance. The significant data and the corresponding experimental tests have already crystallized in the course of basic research and in practice projects as well as during procedures for the granting of numerous approvals for individual cases or general technical approvals. This publication offers a current overview of this topic.
Einleitung großer Biegebeanspruchungen in Plattentragwerke
Authors: Fastabend Michael , Buschmeyer Wilhelm , Schäfers Tobias 
Published: October 2013

AbstractDie konstruktive Durchbildung von Stahlbetonbauteilen ist entscheidend für deren Tragverhalten. So müssen zur Einleitung großer Biegebeanspruchungen im Plattentragwerk spezielle Bewehrungsführungen und entsprechende Modellbildungen angewandt werden. Nur durch geeignete und betongerechte Methoden zur Verankerungsverkürzung lassen sich die Beanspruchungen sicher anschließen.Initiation of high bend loading in slab structures Explanatory notes for construction designThe construction design of reinforced concrete elements is essential for the load‐bearing behavior. For the initiation of high bending loads in slab structures special reinforced layouts and appropriate modeling is necessary. Only with suitable methods of anchoring reduction the loadings can be connected certainly.
cis‐Clerodane Diterpenes from the Liverwort Scapania ciliata
Authors: Liu Na , Zhu Rong‐Xiu , Wang Song , Zhang Jiao‐Zhen , Lin Zhao‐Min , Li Rui‐Juan , Lou Hong‐Xiang 
Published: October 2013

AbstractChemical investigation of the Chinese liverwort Scapania ciliata led to the isolation of four new cis‐clerodane lactones, named ciliatolides A–D (1–4, resp.), among which compound 1 was found to be a tetranorclerodanoid. Their structures were determined by extensive analysis of spectroscopic data, and, in the case of compound 1, together with a single‐crystal X‐ray diffraction analysis. The absolute configurations were established by analysis of the CD spectra and by quantum‐chemical CD calculations. The cytotoxicities of compounds 1–4 were preliminarily tested against the PC3 and MCF‐7 cell lines.
N‐Acylated Alanine Methyl Esters (NAMEs) from Roseovarius tolerans, Structural Analogs of Quorum‐Sensing Autoinducers, N‐Acylhomoserine Lactones
Authors: Bruns Hilke , Thiel Verena , Voget Sonja , Patzelt Diana , Daniel Rolf , Wagner‐Döbler Irene , Schulz Stefan 
Published: October 2013

AbstractThe Roseobacter clade is one of the most important bacteria group living in the ocean. Liquid cultures of Roseovarius tolerans EL 164 were investigated for the production of autoinducers such as N‐acylhomoserine lactones (AHLs) and other secondary metabolites. The XAD extracts were analyzed by GC/MS. Two AHLs, Z7‐C14 : 1‐homoserine lactone (HSL) and C15 : 1‐HSL, were identified. Additionally, the extract contained five compounds with molecular‐ion peaks at m/z 104, 145, and 158, thus exhibiting mass spectra similar to those of AHLs with corresponding peaks at m/z 102, 143, and 156. Isolation of the main compound by column chromatography, NMR analysis, dimethyl disulfide derivatization for the determination of the location of the CC bond and finally synthesis of the compound with the proposed structure confirmed the compound to be (Z)‐N‐(hexadec‐9‐enoyl)alanine methyl ester. Four additional minor compounds were identified as C14 : 0‐, C15 : 0‐, C16 : 0‐, and C17 : 1‐N‐acylated alanine methyl esters (NAMEs). All NAMEs have not been described from natural sources before. A BLASTp search showed the presence of AHL‐producing luxI genes, but no homologous genes potentially responsible for the structurally closely related NAMEs were found. The involvement of the NAMEs in chemical communication processes of the bacteria is discussed.
Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins
Authors: Anderson Carly E. , Vagin Sergei I. , Hammann Markus , Zimmermann Leander , Rieger Bernhard 
Published: October 2013

AbstractTwo dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide–propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis‐para‐tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis‐ortho‐tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time‐resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis‐ortho‐tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements.
Escherichia coli/ADH‐A: An All‐Inclusive Catalyst for the Selective Biooxidation and Deracemisation of Secondary Alcohols
Authors: Paul Caroline E. , Lavandera Iván , Gotor‐Fernández Vicente , Kroutil Wolfgang , Gotor Vicente 
Published: October 2013

AbstractThe nicotinamide adenine dinucleotide regeneration system present in Escherichia coli cells was exploited for the oxidation and deracemisation of secondary alcohols with the overexpressed alcohol dehydrogenase from Rhodococcus ruber DSM 44541 (E. coli/ADH‐A). Thus, various racemic alcohols were selectively oxidised with lyophilised or resting E. coli/ADH‐A cells without need for an external cofactor or co‐substrate. The addition of these substrates to the E. coli/ADH‐A cells in buffer afforded the corresponding ketones and the remaining enantioenriched (R)‐alcohols. This methodology was used for the desymmetrisation of a meso‐diol and for the synthesis of the highly valuable raspberry ketone. Moreover, a biocatalytic concurrent process was developed with the resting cells of E. coli/ADH‐A, ADH from Lactobacillus brevis, and glucose dehydrogenase for the deracemisation of various secondary alcohols, which afforded the desired enantiopure alcohols in more than 99 % ee starting from the racemic mixture. The reaction time of deracemisation of 1‐phenylethanol was estimated to be less than 30 min. The stereoinversion of (S)‐1‐phenylethanol to its pure (R)‐enantiomer was also achieved, which provided a biocatalytic alternative to the chemical Mitsunobu inversion reaction.
Support‐Induced Oxidation State of Catalytic Ru Nanoparticles on Carbon Nanofibers that were Doped with Heteroatoms (O, N) for the Decomposition of NH3
Authors: Marco Yanila , Roldán Laura , Armenise Sabino , García‐Bordejé Enrique 
Published: October 2013

AbstractRu nanoparticles were supported on monoliths that were coated with variously functionalized carbon nanofibers (CNFs), that is, un‐doped CNFs, CNFs that had been post‐treated with H2O2, and CNFs that had been doped with nitrogen during their growth. The Ru uptake (by equilibrium adsorption) onto N‐doped CNFs was larger compared to that on their un‐doped and O‐doped counterparts. The functionalization of the CNF support did not play a significant role in determining the size of the deposited Ru nanoparticles, but it substantially impacted on the sintering under the reaction conditions and on the electron density of the reduced metal. Among the catalysts on the different CNF supports, Ru on N‐CNF exhibited the highest H2 productivity from ammonia decomposition, which pointed to electronic effects that were induced by functionalization of the support.
Chemoselective Hydrogenation Catalyzed by Pd on Spherical Carbon
Authors: Esaki Hiroyoshi , Hattori Tomohiro , Tsubone Aya , Mibayashi Satoko , Sakata Takao , Sawama Yoshinari , Monguchi Yasunari , Yasuda Hidehiro , Nosaka Kazuto , Sajiki Hironao 
Published: October 2013

AbstractWe have developed a highly chemoselective hydrogenation method using a novel palladium catalyst supported on spherical carbon (0.5 % Pd/SC). The 0.5 % Pd/SC exhibited a novel catalytic activity and could achieve the chemoselective hydrogenation of alkynes, alkenes, azides, nitro groups, and aliphatic O‐tert‐butyldimethylsilyl (TBS) ethers without hydrogenolysis of benzyl esters, benzyl ethers, nitriles, aromatic ketones, N‐carbobenzyloxy (N‐Cbz) protective groups, and aromatic O‐TBS ethers.
Kinetics of Bioethanol Production Employing Mono‐ and Co‐Cultures of Saccharomyces cerevisiae and Pichia stipitis
Authors: Dhabhai R. , Chaurasia S. P. , Singh K. , Dalai A. K. 
Published: October 2013

AbstractThe kinetics of bioethanol production using mono‐ and co‐cultures of Saccharomyces cerevisiae and Pichia stipitis with glucose, xylose, and glucose‐xylose sugar mixtures were investigated. A MATLAB® program was formulated for simulation of experimental results in order to get predicted values of ethanol production and sugar consumption and for kinetic parameter estimation. Kinetic parameters implied less extent of substrate and/or product inhibition when the co‐culture scheme of immobilized S. cerevisiae and free P. stipitis was employed for fermentation of mixed sugars. In addition, a high ethanol yield was achieved by applying this co‐culture strategy to wheat straw hydrolysates.
On Two Different Objectives of the Concepts of Ionic Radii
Authors: Liu Jian‐Biao , Schwarz W. H. Eugen , Li Jun 
Published: October 2013

AbstractExperimentally and theoretically derived interatomic distances (D) and ionic radii (R) of more than a hundred monomeric (AX), dimeric (A2X2, ABXY), and crystalline ([AX]) alkali halide species (A=Li, Na, K, Rb, Cs, Fr; X=H, F, Cl, Br, I, At) have been analyzed. Chemists use the word “atomic radius” for two antithetic concepts. LetDCiEE′jj′be the “billion” of distancesibetween two adjacent atoms in the millions of known compounds C from a hundred different elements E in bonding statesj. The common chemical aim is partitioningDapproximately into incrementsREj+RE′j′. This can be achieved with a few (say <thousand) predictive constantsREj. An antipodal aim is specifying in hindsight an electron density feature in the “billion” of different bondsi, by partitioning them into “two billions” of exact bonded radii${R{{{\rm C}i\hfill \atop {\rm E}\hfill}}}$+${R{{{\rm C}i\hfill \atop {\rm E}{^\prime}\hfill}}}$. The constant incremental and the variable bonded radii concepts with the same generic name are useful in different fields of research. Different concepts should be well distinguished, since they have different meaning, different numerical values, and different purposes.
Local Spin Analysis and Chemical Bonding
Authors: Ramos‐Cordoba Eloy , Salvador Pedro , Reiher Markus 
Published: October 2013

AbstractThe electronic structure of main‐group diatomic molecules is discussed in the light of local spin analysis. A deep investigation into the origin of local spins and their coupling is presented. It is shown that the presence of significant local spins in bonded molecules flags deviations from the classical bonding prototypes. For the notorious example of the C2molecule, the local spin analysis indicates that its ground state has all ingredients to be categorized as a diradical.
Mirror‐Image Organometallic Osmium Arene Iminopyridine Halido Complexes Exhibit Similar Potent Anticancer Activity
Authors: Fu Ying , Soni Rina , Romero María J. , Pizarro Ana M. , Salassa Luca , Clarkson Guy J. , Hearn Jessica M. , Habtemariam Abraha , Wills Martin , Sadler Peter J. 
Published: October 2013

AbstractFour chiral OsII arene anticancer complexes have been isolated by fractional crystallization. The two iodido complexes, (SOs,SC)‐[Os(η6‐p‐cym)(ImpyMe)I]PF6 (complex 2, (S)‐ImpyMe: N‐(2‐pyridylmethylene)‐(S)‐1‐phenylethylamine) and (ROs,RC)‐[Os(η6‐p‐cym)(ImpyMe)I]PF6 (complex 4, (R)‐ImpyMe: N‐(2‐pyridylmethylene)‐(R)‐1‐phenylethylamine), showed higher anticancer activity (lower IC50 values) towards A2780 human ovarian cancer cells than cisplatin and were more active than the two chlorido derivatives, (SOs,SC)‐[Os(η6‐p‐cym)(ImpyMe)Cl]PF6, 1, and (ROs,RC)‐[Os(η6‐p‐cym)(ImpyMe)Cl]PF6, 3. The two iodido complexes were evaluated in the National Cancer Institute 60‐cell‐line screen, by using the COMPARE algorithm. This showed that the two potent iodido complexes, 2 (NSC: D‐758116/1) and 4 (NSC: D‐758118/1), share surprisingly similar cancer cell selectivity patterns with the anti‐microtubule drug, vinblastine sulfate. However, no direct effect on tubulin polymerization was found for 2 and 4, an observation that appears to indicate a novel mechanism of action. In addition, complexes 2 and 4 demonstrated potential as transfer‐hydrogenation catalysts for imine reduction.
Chemical Etiology of Nucleic Acid Structure: The Pentulofuranosyl Oligonucleotide Systems: The (1′→3′)‐β‐L‐Ribulo, (4′→3′)‐α‐L‐Xylulo, and (1′→3′)‐α‐L‐Xylulo Nucleic Acids
Authors: Stoop Matthias , Meher Geeta , Karri Phaneendrasai , Krishnamurthy Ramanarayanan 
Published: October 2013

AbstractUnder potentially prebiotic scenarios, ribose (pentose), the component of RNA is formed in meager amounts, as opposed to ribulose and xylulose (pentuloses). Consequently, replacement of ribose in RNA, with pentulose sugars, gives rise to prospective oligonucleotide candidates that are potentially prebiotic structural variants of RNA that could be formed by the same type of chemical pathways that gave rise to RNA from ribose. The potentially natural alternative (1′→3′)‐ribulo oligonucleotides and (4′→3′)‐ and (1′→3′)‐xylulo oligonucleotides consisting of adenine and thymine were synthesized and found to exhibit no self‐pairing or cross‐pairing with RNA. This signifies that even though pentulose sugars may have been abundant in a prebiotic scenario, the pentulose nucleic acids (NAs), if and when formed, would not have been competitors of RNA, or interfered with the emergence of RNA as a functional informational system. The reason for the lack of base pairing in pentulose NA highlights the contrasting and central role played by the furanosyl ring in RNA and pentulose NA, enabling and optimizing the base pairing in RNA, while impeding it in pentulose NA.
Experimental and Computational Studies of Anti‐Bredt Amidinium Salts
Authors: Martin David , Lassauque Nicolas , Steinmann Florian , Manuel Gerald , Bertrand Guy 
Published: October 2013

AbstractExperimental and computational investigations of anti‐Bredt amidinium salts are presented. Calculations show that the pyramidalization of an amino group can significantly destabilize the formal carbocation center of amidiniums, due to the decreased π donation. In some cases, the unfavorable ‐I effect of nitrogen surpasses its beneficial +M effect, and amidiniums become less stable than iminiums. It is shown that although 1‐aza‐3‐azonia[3.3.1]bicyclo‐non‐2‐enes can be isolated, they feature a nonclassical reactivity, which is more typical for iminium than amidinium salts, such as pronounced electrophilicity and azomethineylide instead of carbene formation.
Expanded Organic Building Units for the Construction of Highly Porous Metal–Organic Frameworks
Authors: Kong Guo‐Qiang , Han Zhi‐Da , He Yabing , Ou Sha , Zhou Wei , Yildirim Taner , Krishna Rajamani , Zou Chao , Chen Banglin , Wu Chuan‐De 
Published: October 2013

AbstractTwo new organic building units that contain dicarboxylate sites for their self‐assembly with paddlewheel [Cu2(CO2)4] units have been successfully developed to construct two isoreticular porous metal–organic frameworks (MOFs), ZJU‐35 and ZJU‐36, which have the same tbo topologies (Reticular Chemistry Structure Resource (RCSR) symbol) as HKUST‐1. Because the organic linkers in ZJU‐35 and ZJU‐36 are systematically enlarged, the pores in these two new porous MOFs vary from 10.8 Å in HKUST‐1 to 14.4 Å in ZJU‐35 and 16.5 Å in ZJU‐36, thus leading to their higher porosities with Brunauer–Emmett–Teller (BET) surface areas of 2899 and 4014 m2 g−1 for ZJU‐35 and ZJU‐36, respectively. High‐pressure gas‐sorption isotherms indicate that both ZJU‐35 and ZJU‐36 can take up large amounts of CH4 and CO2, and are among the few porous MOFs with the highest volumetric storage of CH4 under 60 bar and CO2 under 30 bar at room temperature. Their potential for high‐pressure swing adsorption (PSA) hydrogen purification was also preliminarily examined and compared with several reported MOFs, thus indicating the potential of ZJU‐35 and ZJU‐36 for this important application. Studies show that most of the highly porous MOFs that can volumetrically take up the greatest amount of CH4 under 60 bar and CO2 under 30 bar at room temperature are those self‐assembled from organic tetra‐ and hexacarboxylates that contain m‐benzenedicarboxylate units with the [Cu2(CO2)4] units, because this series of MOFs can have balanced porosities, suitable pores, and framework densities to optimize their volumetric gas storage. The realization of the two new organic building units for their construction of highly porous MOFs through their self‐assembly with [Cu2(CO2)4] units has provided great promise for the exploration of a large number of new tetra‐ and hexacarboxylate organic linkers based on these new organic building units in which different aromatic backbones can be readily incorporated into the frameworks to tune their porosities, pore structures, and framework densities, thus targeting some even better performing MOFs for very high gas storage and efficient gas separation under high pressure and at room temperature in the near future.
Titanocene(III)‐Catalyzed 6‐exo Versus 7‐endo Cyclizations of Epoxypolyprenes: Efficient Control and Synthesis of Versatile Terpenic Building Blocks
Authors: Justicia José , Jiménez Tania , Miguel Delia , Contreras‐Montoya Rafael , Chahboun Rachid , Álvarez‐Manzaneda Enrique , Collado‐Sanz Daniel , Cárdenas Diego J. , Cuerva Juan M. 
Published: October 2013

AbstractIn this article, a complete study on the selectivity of titanocene(III) cyclization of epoxypolyprenes is presented. The requirements for the formation of six‐ or seven‐membered rings during these cyclizations are determined, taking into account the different substitution pattern in the epoxypolyprene precursor. Thus, a complete selectivity to 6‐exo or 7‐endo cyclization process has been achieved, yielding mono‐, bi‐, and even tricyclic compounds, constituting a new and efficient access to this type of derivative. Additionally, this procedure opens the possibility to prepare excellent building blocks for the synthesis of polycyclic compounds with a trisubstituted oxygenated function, which is present in several natural terpenes.
ChemInform Abstract: Barium Dierbium(III) Tetrasulfide.
Authors: Mesbah Adel , Stojko Wojciech , Ibers James A. 
Published: October 2013

AbstractOrange needles of BaEr2S4 are obtained during an investigation of the Ba/Er/U/S system by solid state reaction of a mixture of 238U, Er, BaS, and S in the ratio 1:1:3:3 (evacuated C‐coated fused silica tube, 1273 K, 8 d, cooling rate 3 K/h) together with black crystals of Sb2S3 and US2.
ChemInform Abstract: Stability of Ruddlesden—Popper‐Structured Oxides in Humid Conditions.
Authors: Lehtimaeki M. , Yamauchi H. , Karppinen M. 
Published: October 2013

AbstractThe influence of oxygen content of the Ruddlesden—Popper‐structured oxides Sr3FeMO7‐δ (M: Ni, Mn, Ti) on the water‐intercalation reaction is investigated.
ChemInform Abstract: Asymmetric Synthesis of Carbocycles: Use of Intramolecular Conjugate Displacement.
Authors: Sreedharan Dinesh , Clive Derrick L. J. 
Published: October 2013

AbstractIntramolecular conjugate displacement (ICD) is applied to the Morita—Baylis—Hillman adducts formed from L‐menthyloxy substituted furanones and aldehydes that are substituted in the γ‐ or δ‐position by geminal phenylthio groups.
ChemInform Abstract: Conjugated Enyne Synthesis by Rearrangement of Acetylenic Epoxides Mediated by Low‐Valence Organotitanium and Organozirconium Reagents.
Authors: Denichoux Aurelien , Cyklinsky Mathieu , Chemla Fabrice , Ferreira Franck , Perez‐Luna Alejandro 
Published: October 2013

AbstractDeoxygenation of epoxides with Negishi reagents, generated in situ, offers a convenient synthesis of the target compounds with excellent (E)‐selectivity.
ChemInform Abstract: Carbamoyl Anion Addition to N‐Sulfinyl Imines: Highly Diastereoselective Synthesis of α‐Amino Amides.
Authors: Reeves Jonathan T. , et al. et al. 
Published: October 2013

AbstractThis firstly presented asymmetric addition reaction is simple, atom‐economical, and gives direct access to a wide range of different substituted α‐amido amides as well as to dipeptides, e.g. compound (VI).
ChemInform Abstract: Copper‐Catalyzed Aerobic Oxidative Amination of Arylboronic Acid with Aminal under Base‐Free Conditions.
Authors: Zhou Yanping , Xie Yinjun , Yang Lei , Xie Pan , Huang Hanmin 
Published: October 2013

AbstractAmination is carried out in the presence of air with symmetrical aminals to give the products in moderate yields.