bluuebunny/crossref_metadata_2025_split huggingface dataset:
1‐Alkynylphosphines and Their Derivatives as Key Starting Materials in Creating New Phosphines
Authors: Kondoh Azusa , Yorimitsu Hideki , Oshima Koichiro 
Published: January 2010

AbstractThis Focus Review summarizes transformations of 1‐alkynylphosphines and their derivatives directed toward the synthesis of new phosphines. Owing to the importance of organophosphines as ligands for transition metal catalysts, development of efficient methods for the synthesis of new phosphines is quite important. 1‐Alkynylphosphines and their derivatives have been emerging as useful precursors for the creation of new phosphines. Chemical modifications of the carbon–carbon triple bonds, including nucleophilic addition and cycloaddition, lead to a wide range of new useful phosphines that are otherwise difficult to synthesize.
Binding of Multivalent Anionic Porphyrins to V3 Loop Fragments of an HIV‐1 Envelope and Their Antiviral Activity
Authors: Watanabe Kenji , Negi Shigeru , Sugiura Yukio , Kiriyama Akiko , Honbo Akino , Iga Katsumi , Kodama Eiichi N. , Naitoh Takeshi , Matsuoka Masao , Kano Koji 
Published: January 2010

AbstractInteractions of multivalent anionic porphyrins and their iron(III) complexes with cationic peptides, V3Ba‐L and V3IIIB, which correspond to those of the V3 loop regions of the gp120 envelope proteins of the HIV‐1Ba‐L and HIV‐1IIIB strains, respectively, are studied by UV/Vis, circular dichroism, 1H NMR, and EPR spectroscopy, a microcalorimetric titration method, and anti‐HIV assays. Tetrakis(3,5‐dicarboxylatophenyl)porphyrin (P1), tetrakis[4‐(3,5‐dicarboxylatophenylmethoxy)phenyl]porphyrin (P2), and their ferric complexes (FeIIIP1 and FeIIIP2) were used as the multivalent anionic porphyrins. P1 and FeIIIP1 formed stable complexes with both V3 peptides (binding constant K>106 M−1) through combined electrostatic and van der Waals interactions. Coordination of the His residues in V3Ba‐L to the iron center of FeIIIP1 also played an important role in the complex stabilization. As P2 and FeIIIP2 form self‐aggregates in aqueous solution even at low concentrations, detailed analysis of their interactions with the V3 peptides could not be performed. To ascertain whether the results obtained in the model system are applicable to a real biological system, anti‐HIV‐1BA‐L and HIV‐1IIIB activity of the porphyrins is examined by multiple nuclear activation of a galactosidase indicator (MAGI) and 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assays. There is little correlation between chemical analysis and actual anti‐HIV activity, and the size rather than the number of the anionic groups of the porphyrin is important for anti‐HIV activity. All the porphyrins show high selectivity, low cytotoxicity, and high viral activity. FeIIIP1 and FeIIIP2 are used for the pharmacokinetic study. Half‐lives of these iron porphyrins in serum of male Wistar rats are around 4 to 6 h owing to strong interaction of these porphyrins with serum albumin.
1,4‐Butanediol as a Reducing Agent in Transfer Hydrogenation Reactions
Authors: Maytum Hannah C. , Francos Javier , Whatrup David J. , Williams Jonathan M. J. 
Published: January 2010

Abstract1,4‐Butanediol is able to deliver two equivalents of H2 in hydrogen‐transfer reactions to ketones, imines, and alkenes. Unlike simple alcohols, which establish equilibrium in the reduction of ketones, 1,4‐butanediol acts essentially irreversibly owing to the formation of butyrolactone, which acts as a thermodynamic sink. It is therefore not necessary to use 1,4‐butanediol in great excess in order to achieve reduction reactions. In addition, allylic alcohols are reduced to saturated alcohols through an isomerization/reduction sequence using a ruthenium catalyst with 1,4‐butanediol as the reducing agent. Imines and alkenes are also reduced under similar conditions.
Platelet Graphite Nanofibers for Electrochemical Sensing and Biosensing: The Influence of Graphene Sheet Orientation
Authors: Ambrosi Adriano , Sasaki Toshio , Pumera Martin 
Published: January 2010

AbstractHere, we demonstrate that platelet graphite nanofibers (PGNFs) exhibit fast heterogeneous electron‐transfer rates for a wide variety of compounds such as FeCl3, ferrocyanide, dopamine, uric acid, ascorbic acid, and the reduced form of β‐nicotinamide adenine dinucleotide. The electrochemical properties of PGNFs are superior to those of multiwalled carbon nanotubes (MWCNTs) or graphite microparticles (GMPs). Transmission electron microscopy and Raman spectroscopy reveal that this arises from the unique graphene sheet orientation of such platelet nanofibers, which accounts for their unparalleled high ratio of graphene edge planes versus basal planes.
Structural Diversity of Calcium Organocuprates(I): Synthesis of Mesityl Cuprates via Addition and Transmetalation Reactions of Mesityl Copper(I)
Authors: Krieck Sven , Görls Helmar , Westerhausen Matthias 
Published: January 2010

AbstractThe addition of [(L)4Ca(I)Mes] (Lewis base L=thf, Et2O) to mesityl copper(I) and the transmetalation reaction of mesityl copper(I) with activated calcium are suitable pathways for the synthesis of dimesityl cuprates(I) of calcium. However, the structures of the calcium cuprates(I) depend on the preparative procedure. The transmetalation reaction leads to the formation of [Mes‐Cu‐Mes]− anions whereas the addition yields dinuclear [(Mes‐Cu)2(μ‐Mes)]− anions. The solvent‐separated counterions are [Ca(thf)6]2+ and [(thf)5CaI]+, respectively. In contrast to these findings, the addition of [(L)4Ca(I)Mes] to mesityl copper(I) in an Et2O/toluene mixture led to formation of tetrameric solvent‐free iodocalcium dimesityl cuprate(I) [ICa(μ‐η1,η6‐Mes2Cu)]4, representing a rare example of a heavy Normant‐type organocuprate.
On the correlation of “static” and “dynamic” stiffness moduli of non‐cohesive soils
Authors: Wichtmann Torsten , Triantafyllidis Theodor 
Published: January 2010

AbstractThe secant stiffness of the stress – strain – hysteresis during a cyclic or dynamic loading with very small strain amplitudes is sometimes called “dynamic” stiffness of a soil. In contrast, a “static” stiffness is obtained from the first loading curve in oedometric or triaxial tests. Indeed, the difference between “dynamic” (small‐strain) and “static” (large‐strain) stiffness moduli is due to the different magnitude of strain or strain amplitude and not due to different loading rates. The small strain stiffness is an important design parameter for foundations subjected to a cyclic or dynamic loading. However, its determination in situ or from laboratory tests is laborious and expensive. In practice, the small‐strain stiffness is often estimated by means of a diagram correlating “dynamic” and “static” stiffness moduli. However, the assumptions and the range of applicability of this correlation are not clear. The present paper presents an inspection of this correlation for four sands with different grain size distribution curves. The “static” stiffness was obtained from tests with monotonic oedometric or triaxial compression. The “dynamic” stiffness was determined in resonant column tests and from measurements of the P‐wave velocity. For some of the tested sands, significant deviations of the experimental data from the correlation actually used in practice were obtained. Modified correlations are proposed in the paper.
Calculation of deformations of an underwater excavation using parameters of Berlin sand from a hypoplastic model
Authors: Herle Ivo , Mayer Peter‐Michael 
Published: January 2010

AbstractSoil parameters are always related to particular constitutive laws. For the application of elastic‐perfectly plastic constitutive models in commercial FE codes, it is necessary to determine a large number of parameters because soil stiffness and friction angle are pressure‐ and density‐dependent. On the contrary, the hypoplastic model includes only pressure‐ and density‐independent constants which are closely related to the properties of grain assemblies. The determination of hypoplastic parameters is demonstrated for Berlin sand, and it is shown how conventional stiffness and strength quantities can be calculated using hypoplasticity. Afterwards, a FE calculation of an anchored wall in Berlin is performed with the Mohr‐Coulomb constitutive law and soil parameters from the hypoplastic model. Results of the calculation coincide well with the measured values. Nevertheless, limitations of such a procedure are pointed out and the need for more comprehensive constitutive laws in complex boundary value problems is emphasized.
Sichtbeton aus Spritzbeton
Authors: Hankers Christoph 
Published: January 2010

AbstractDie Verwendung von Spritzbeton für die Instandsetzung und Verstärkung von Bauwerken, für den Tunnelbau und zur Sicherung von Baugruben und Stützwänden ist Stand der Technik und wird millionenfach angewandt. Auch der Bau von Schalentragwerken ist eine Spritzbetondomaine. Weniger bekannt ist die Tatsache, dass mit Spritzbeton auch optisch ansprechende Flächen und Strukturen geschaffen werden können. Vereinzelt wird Spritzbeton bewusst zur Gestaltung von Fassaden eingesetzt. Neu ist die Methode, profilierten Spritzbeton bewusst als Sichtbeton zu verwenden. In Kombination mit einer temporären, in die Oberfläche eingelegten Matrize ergeben sich interessante gestalterische Perspektiven und Möglichkeiten. Sie werden anhand von Ausführungsbeispielen erläutert.
Bauteile aus Stahlfaserbeton und stahlfaserverstärktem Stahlbeton
Authors: Gödde Lars , Strack Mathias , Mark Peter 
Published: January 2010

AbstractMit der zu erwartenden Einführung der Richtlinie “Stahlfaserbeton” des Deutschen Ausschuss für Stahlbeton (DAfStb) entsteht für den Verbundwerkstoff Stahlfaserbeton ein neues, breites Spektrum an zusätzlichen Anwendungsmöglichkeiten. Durch die Wirkung der Fasern im Beton können nach Überschreitung der Betonzugfestigkeit nennenswerte Kräfte zwischen den Rissufern übertragen und bei der rechnerischen Erfassung des Tragverhaltens berücksichtigt werden. Im Aufsatz werden Vorgehensweisen, Hilfsmittel und ein auf Tabellenkalkulationen und Optimierungsmethoden basierendes Programm zur Biegebemessung und Verformungsabschätzung von Querschnitten und Systemen aus Stahlfaserbeton und stahlfaserverstärktem Stahlbeton entwickelt. Grundlage sind die bekannten Bemessungsansätze und ‐hilfsmittel für Stahlbetonquerschnitte. Die Anwendung der Hilfsmittel – auch für Verformungsabschätzungen auf Basis nichtlinearer Verfahren – zeigen zwei Beispiele.Structural Elements of Steel Fibre Reinforced Concrete with or without Bar Reinforcement Tools for Design and Deflection Estimations according to the Guideline “Stahlfaserbeton” by DAfStbThe expected release of the guideline “Stahlfaserbeton” by ‘German Committee for Reinforced Concrete’ (DAfStb) offers a wide application range for the composite material steel fibre reinforced concrete (SFRC). Due to additional steel fibres in concrete considerable tension forces can be transferred between crack edges after reaching plain concrete's tensile strength. These forces can be accounted for in calculation of load bearing capacity. Adapted from common design methods and tools for plain reinforced concrete new procedures, tools and a computer application – based on spreadsheet analysis and optimisation methods – for SFRC are presented in this article. These allow for both bending design as well as deflection estimation of crosssections and structural systems made of SFRC with and without additional rebars. Their application – also in case of deflection estimation using non‐linear methods – is demonstrated in two elaborated examples.
Expression, purification, and analysis of unknown translation factors from Escherichia coli: A synthesis approach
Authors: Walter Justin D. , Littlefield Peter , Delbecq Scott , Prody Gerry , Spiegel P. Clint 
Published: January 2010

AbstractNew approaches are currently being developed to expose biochemistry and molecular biology undergraduates to a more interactive learning environment. Here, we propose a unique project‐based laboratory module, which incorporates exposure to biophysical chemistry approaches to address problems in protein chemistry. Each of the experiments described herein contributes to the stepwise process of isolating, identifying, and analyzing a protein involved in a central biological process, prokaryotic translation. Students are provided with expression plasmids that harbor an unknown translation factor, and it is their charge to complete a series of experiments that will allow them to develop hypotheses for discovering the identity of their unknown (from a list of potential candidates). Subsequent to the identification of their unknown translation factor, a series of protein unfolding exercises are performed employing circular dichroism and fluorescence spectroscopies, allowing students to directly calculate thermodynamic parameters centered around determining the equilibrium constant for unfolding as a function of denaturant (temperature or chemical). The conclusion of this multi‐part laboratory exercise consists of both oral and written presentations, emphasizing synthesis of the roles of each translation factor during the stepwise process of translation.
Bridging the educational research‐teaching practice gap
Authors: Anderson Trevor R. , Rogan John M. 
Published: January 2010

AbstractStudent assessment is central to the educational process and can be used for multiple purposes including, to promote student learning, to grade student performance and to evaluate the educational quality of qualifications. It is, therefore, of utmost importance that assessment instruments are of a high quality. In this article, we present various tools that instructors could use, both to improve instrument design and validity before presentation to students and, to evaluate the reliability and quality of the assessment after students have answered the questions. In keeping with our goals of the Bridging‐the‐Gap series, we also present various ideas from the educational literature regarding the evaluation of assessment quality and end with a list of criteria that instructors could use to guide their evaluation process.
Incorporating a collaborative web‐based virtual laboratory in an undergraduate bioinformatics course
Authors: Weisman David 
Published: January 2010

AbstractFace‐to‐face bioinformatics courses commonly include a weekly, in‐person computer lab to facilitate active learning, reinforce conceptual material, and teach practical skills. Similarly, fully‐online bioinformatics courses employ hands‐on exercises to achieve these outcomes, although students typically perform this work offsite. Combining a face‐to‐face lecture course with a web‐based virtual laboratory presents new opportunities for collaborative learning of the conceptual material, and for fostering peer support of technical bioinformatics questions. To explore this combination, an in‐person lecture‐only undergraduate bioinformatics course was augmented with a remote web‐based laboratory, and tested with a large class. This study hypothesized that the collaborative virtual lab would foster active learning and peer support, and tested this hypothesis by conducting a student survey near the end of the semester. Respondents broadly reported strong benefits from the online laboratory, and strong benefits from peer‐provided technical support. In comparison with traditional in‐person teaching labs, students preferred the virtual lab by a factor of two. Key aspects of the course architecture and design are described to encourage further experimentation in teaching collaborative online bioinformatics laboratories.
Accessing the vocal folds by transcutaneous injection
Authors: Pearson William , Hutchinson Christoph T. , Noordzij J. Pieter 
Published: January 2010

AbstractThis study tested three techniques and two approaches to access the vocal fold (VF) by transcutaneous injection using a cadaver model. The three techniques include an anatomically informed geometric technique, flexible laryngoscope (FL) guidance, and planned injection with use of computed tomography (CT). The two approaches for injection include the thyrohyoid membrane (THM) and the cricothyroid membrane (CTM). The hypothesis was that the VF is more reliably reached with techniques using technological visualization and the THM and CTM provides equal access to the VF. A geometric approach to the VF was developed and tested on seven formalin‐fixed human cadavers with three injections of 0.5 ml pigmented acrylic polymer through the CTM and one through the THM. The FL‐guided technique through the THM and the CTM was tested on eight formalin‐fixed human cadavers and the CT informed technique on two subjects. All tests were inspected by dissection and results recorded. Pertinent measurements and characteristics of each technique were recorded. Data were analyzed for statistical significance for each approach and technique. A chi‐square analysis revealed that a technology guided technique was more successful than anatomical knowledge alone (X2 = 6.55, P = 0.01). The null hypothesis that the VF was equally accessed through the THM and the CTM was rejected (X2 = 5.33, P = 0.02). We found that technology guided visualization is better than anatomical knowledge alone in accessing the VF. We also found that the CTM approach provides more reliable access to the entire length of the VF. Clin. Anat. 23:270–276, 2010. © 2010 Wiley‐Liss, Inc.
Enzymatic Thioxyloside Synthesis: Characterization of Thioglycoligase Variants Identified from A Site‐Saturation Mutagenesis Library of Bacillus Circulans Xylanase
Authors: Armstrong Zachary , Reitinger Stephan , Kantner Terrence , Withers Stephen G. 
Published: January 2010

AbstractThioglycoligases are engineered enzymes for the synthesis of thioglycosides that are derived from retaining glycosidases by replacing the acid/base catalyst. The optimal choice of substitution for the acid/base mutant is currently unknown, so to investigate this question a complete acid/base library of the model glycosidase Bacillus circulans xylanase (Bcx) was generated by using site‐saturation mutagenesis. A novel screening approach combining active site titration with semiquantitative product analysis by thin layer chromatography was established and used to evaluate specific activities of each mutant enzyme within crude cell lysates. The six most active Bcx variants were analyzed in more detail, a pH optimum of 8.5 was established and the identity of reaction products was confirmed. Optimal choices for substitution were small, preferably polar amino acids such as threonine, cysteine, and serine. We discuss the resultant data in the context of previously published studies on thioglycoligases.
Mechanism of CO Disproportionation on Reduced Ceria
Authors: Liu Yi , Wen Cun , Guo Yun , Liu Xiaohui , Ren Jiawen , Lu Guanzhong , Wang Yanqin 
Published: January 2010

AbstractCO disproportionation produces carbon deposits that cover active sites and induce catalyst deactivation. However, understanding of this detrimental reaction on reduced ceria is deficient. Herein, the reversibility and reaction mechanism of CO disproportionation on reduced ceria are investigated. The reversibility of the CO disproportionation was studied by CO pulse, isotopic oxygen tracer, thermal analysis, and CO2 pulse experiments. In situ diffuse‐reflectance infrared Fourier transform spectra indicate that the CO bond of the CO molecule on Ce3+ ion is weakened. With CO bond dissociation, asymmetrical inorganic carboxylate species are formed. These species are the key reaction intermediates in CO disproportionation and are further converted to produce CO2. EPR experiments indicate that the unpaired electrons produced by the reduction weaken the CO bond through back‐donation of electrons.
Simultaneous Elimination of Pyrophoricity and Enhancement of Activity of Raney Nickel by Carbon Deposition: Synthesis of Highly Active NiC Catalysts
Authors: Mahata Nagendranath , Cunha Adelino F. , Órfão José J. M. , Figueiredo José L. 
Published: January 2010

AbstractNickel‐carbon composite materials (NiC catalysts) are synthesized by decomposing methane over Raney‐type skeletal nickel catalysts. The NiC catalysts are evaluated in the hydrogenation of cyclooctene, cyclooctadiene, nitrobenzene, and para‐chloronitrobenzene. Characterization by scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy reveals that the catalysts consist of nickel in its metallic form with superficial oxide layers, carbon, and aluminum oxide/hydroxide. The catalysts exhibited excellent hydrogenation activity, superior to the parent Raney nickel.
Effect of Ultrasound on SO2 Desorption from Sodium Alkali Desulphurization Regeneration Solution
Authors: Xu H. , Zhang S.‐T. , Lu X.‐B. , Liu Y. , Yu X.‐Y. 
Published: January 2010

AbstractThe influence of an ultrasonic field on SO2 desorption from sodium alkali desulfurization regeneration solution was studied in this work. The SO2 desorption experiments were carried out in the presence and absence of ultrasound at 25 kHz. The results showed that the use of ultrasound could enhance the SO2 desorption rate from the sodium alkali desulfurization regeneration solution. By analyzing the composition of regeneration solutions with different pH values, two steps for the desorption process were proposed, both with and without ultrasound conditions, i.e., the first step was the decomposition of sulfurous acid (H2SO3), and the second step was the decomposition of sodium bisulfite (NaHSO3). Furthermore, the use of ultrasound was seen to promote the first step, while it was not seen to have a significant effect on the second step. It was also found that the decomposition of H2SO3 in the first step could be considered as a gas mass transfer process from the liquid phase to the gaseous phase and the overall volumetric mass transfer coefficient, KL·a, increased on using ultrasound compared to the value in the absence of an ultrasonic field.
High Temperature Cyclic Oxidation Resistance of Iron Chromium Base Alloys
Authors: Lins V. F. C. , Castro M. M. R. , Domingues R. Z. , Matencio T. 
Published: January 2010

AbstractThe cyclic oxidation behavior of an experimental stainless ferritic steel, without molybdenum and with copper‐aluminum‐titanium‐lanthanum additions, developed for solid oxide fuel cell applications, was evaluated and compared with the oxidation behavior of commercial austenitic and ferritic stainless steels. For the cyclic oxidation tests, the steel samples were tested at temperatures ranging from 600 to 800 °C. The experimental ferritic stainless steel showed the highest cyclic oxidation behavior among the studied steels at 700 °C and 800 °C, presenting a parabolic and logarithmic kinetics, respectively.