bluuebunny/crossref_metadata_2025_split huggingface dataset:
Twofold Extrusion Reactions
Authors: James Guziec Lynn , Guziec Frank S. 
Published: February 2015

AbstractTwofold extrusion reactions are chemical transformations in which two small inorganic molecules or atoms connecting carbon or nitrogen atoms are lost, generating the corresponding carbon‐carbon or carbon‐nitrogen double bonds. These reactions are particularly useful for the preparation of sterically hindered alkenes and imines. The inorganic species liberated in twofold extrusion reactions can be molecular nitrogen, sulfur, selenium, tellurium, sulfur dioxide, sulfur monoxide, carbon dioxide or carbon monoxide.The most common precursors for twofold extrusion reactions are 1,3,4‐thiadiazolines, which thermally extrude molecular nitrogen affording thiiranes. These thiiranes can be readily desulfurized to afford the corresponding alkenes using tertiary phosphines. The corresponding 1,3,4‐selenadiazolines thermally extrude both molecular nitrogen and atomic selenium directly affording alkenes. Alkenes can also be prepared by formal extrusions of molecular nitrogen plus sulfur dioxide or sulfur monoxide. Extremely sterically hindered imines can be prepared by extrusions of molecular nitrogen and sulfur or selenium from in situ generated heterocyclic precursors. Other less common twofold extrusion reactions are also reported.The detailed preparations of the required precursors for the twofold extrusion reactions as well as the mechanisms of these extrusion processes are discussed in this chapter. The utility of twofold extrusion reactions in the preparations of ‘molecular rotors’ and other extremely sterically hindered alkenes is presented. The steric limitations of the twofold extrusion reactions are discussed along with comparisons of these reactions with other alkene‐ and imine‐forming synthetic methods. The Tabular Survey covers material through the end of 2009.
On the Role of the Electronic Structure of the Heteronuclear Oxide Cluster [Ga2Mg2O5].+ in the Thermal Activation of Methane and Ethane: An Unusual Doping Effect
Authors: Li Jilai , Wu Xiao‐Nan , Schlangen Maria , Zhou Shaodong , González‐Navarrete Patricio , Tang Shiya , Schwarz Helmut 
Published: February 2015

AbstractThe reactivity of the heteronuclear oxide cluster [Ga2Mg2O5].+, bearing an unpaired electron at a bridging oxygen atom (Ob.−), towards methane and ethane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). Hydrogen‐atom transfer (HAT) from both methane and ethane to the cluster ion is identified experimentally. The reaction mechanisms of these reactions are elucidated by state‐of‐the‐art quantum chemical calculations. The roles of spin density and charge distributions in HAT processes, as revealed by theory, not only deepen our mechanistic understanding of CH bond activation but also provide important guidance for the rational design of catalysts by pointing to the particular role of doping effects.
The association between maternal parity and birth defects
Authors: McNeese Melanie L. , Selwyn Beatrice Josephine , Duong Hao , Canfield Mark , Waller Dorothy Kim 
Published: February 2015

BACKGROUNDPrevious studies observed that first birth is associated with an increased risk of some categories of birth defects. However, multiple statistical tests were conducted and it was unclear which of these associations would be replicated in a larger study. We used a large database to assess the association between maternal parity and 65 birth defects including birth defects that have not been previously studied.METHODSUsing data from the Texas Birth Defects Registry for years 1999–2009, the risk of a birth defect occurring in a first, third, or fourth or higher birth was compared to the risk of a birth defect occurring in a second birth.RESULTSWomen having their first birth had significantly increased odds of having an infant with 24 of 65 categories of birth defects when compared to women having their second birth. We also observed associations between first birth and an increased risk of five birth defects not previously reported (small penis, preaxial polydactyly, anomalies of the thoracic vertebrae, anomalies of the lumbar vertebrae, and sacroccygeal anomalies). Women having their third or fourth or higher birth had significantly increased odds of giving birth to infants with five of 65 birth defects when compared to second births.CONCLUSIONSOur observations regarding the categories of birth defects that were associated with first births were highly consistent with observations from two previous studies. Research into biological, behavioral, and environmental factors that may increase the risk of specific birth defects among first births is needed to further explore these associations. Birth Defects Research (Part A) 103:144–156, 2015 © 2015 Wiley Periodicals, Inc.
Understanding of altered N‐glycosylation‐related gene expression in recombinant Chinese hamster ovary cells subjected to elevated ammonium concentration by digital mRNA counting
Authors: Ha Tae Kwang , Kim Yeon‐Gu , Lee Gyun Min 
Published: February 2015

ABSTRACTTo understand the effects of ammonium on N‐glycosylation, recombinant Chinese hamster ovary (rCHO) cells that produce the Fc‐fusion protein were cultivated in serum‐free suspension cultures with 10 mM ammonium addition. The addition of ammonium to the cultures reduced the relative proportion of acidic isoforms and sialic acid content of an Fc‐fusion protein. Fifty two N‐glycosylation‐related gene expressions were assessed by the NanoString nCounter system, which provides a digital readout using custom‐designed color‐coded probes. Among these queried genes, thirteen genes (gale, nans, gpi, man2a1, b4galt5, b4galt7, st3gal2, st3gal5, glb1, hexa, hexb, neu1, and neu3) were up‐regulated over 1.5 times in the culture with ammonium addition after 5 days of culture; however, none of the 54 genes were significantly different after 3 days of culture. In particular, the expression level of neu1 (sialidase‐1) and neu3 (sialidase‐3), which play a role in reduction of sialylation, increased over 2 times. Likewise, the protein expression levels of sialidase‐1 and sialidase‐3 determined by Western blot analysis were also increased significantly in the culture with ammonium addition. Transient transfection of neu‐1 or neu3‐targeted siRNAs significantly improved the sialic acid content of the Fc‐fusion protein in the culture with ammonium addition, indicating that the decreased sialic acid content was in part due to the increased expression level of sialidase. Taken together, the results obtained in this study provide a better understanding of the detrimental effect of ammonium on N‐glycosylation, especially sialylation, in rCHO cells. Biotechnol. Bioeng. 2015;112: 1583–1593. © 2015 Wiley Periodicals, Inc.
Simultaneous determination of camptothecin and 10‐hydroxycamptothecine in the Camptotheca acuminate, its medicinal preparation and in rat plasma by liquid chromatography with fluorescence detection
Authors: Li Peng , Chen Qinhua , Yu Fei , Xie Xiaoyu , Wang Sicen 
Published: February 2015

AbstractCamptotheca acuminata Decne is an important medicinal plant that contains various cytotoxic alkaloids, such as camptothecine (CPT) and 10‐hydroxycamptothecine (HCPT). A rapid and sensitive liquid chromatography with fluorescence detection (LC‐FLD) method for the quantification of CPT and HCPT is described. The separation was carried out on a DL‐Cl8 column (4.6 × 150 mm, 5 µm), with the mobile phase of acetonitrile–sodium dihydrogen phosphate buffer (10 mm) using an gradient elution at the flow rate of 0.6 mL/min. The LC‐FLD method was validated for linearity, sensitivity, accuracy and precision, and then used to determine the content of the above components. The lower detection limits of CPT and HCPT were 0.4 and 0.1 ng/mL, respectively. The precision was <1.58% and the mean recovery of the analytes was 96.0–98.6%. The LC‐FLD method was successfully applied to determine CPT and HCPT in real samples including C. acuminate, HCPT injection and rat plasma. Copyright © 2015 John Wiley & Sons, Ltd.
Structural Transformation and Hysteretic Sorption of Light Hydrocarbons in a Flexible Zn–Pyrazole–Adenine Framework
Authors: Fu Hong‐Ru , Zhang Jian 
Published: February 2015

AbstractA three‐dimensional metal–organic framework (MOF) was synthesized by combining 4‐pyrazolecarboxylic acid and adenine. This MOF exhibits reversible flexibility and breathing adsorption behaviors in response to light hydrocarbons, with high capacity. The flexibility of the structural transitions was studied on the molecular scale by obtaining the crystal structures at 303, 353 and 373 K. The bridging nitrogen atoms of the pyrazolate rings act as a “kneecap” around the M⋅⋅⋅M axis, which causes the rotation of ligands around the M⋅⋅⋅M axis in response to external stimulus, thus giving rise to the deformation of the framework structure.
Beschleunigter Sinkprozess fester Partikel bei laminarer und turbulenter Umströmung
Authors: Glöckner Hannes , Hagemeier Thomas , Müller Peter , Roloff Christoph , Thévenin Dominique , Tomas Jürgen 
Published: February 2015

AbstractDie Trennung von Partikelkollektiven erfolgt meist anhand der stationären Sinkgeschwindigkeit als Trennmerkmal. Die Bewegungszustände der Partikel werden bisher sehr aufwendig durch die numerische Lösung des Kräftegleichgewichts ermittelt. In dieser Arbeit werden algebraische Gleichungen hergeleitet, die die zeitlichen Änderungen von Sinkgeschwindigkeit und ‐weg bei laminarer und turbulenter Partikelumströmung beschreiben und lediglich von der Partikelgröße, ‐dichte und ‐form abhängen. Unabhängig von der Anfangsgeschwindigkeit lassen sich charakteristische Werte ermitteln, mit denen der Zeitpunkt abgeschätzt werden kann, ab dem eine ausreichende Annäherung an die stationäre Sinkgeschwindigkeit erreicht ist.
Focal cartilage defect compromises fluid‐pressure dependent load support in the knee joint
Authors: Dabiri Yaghoub , Li LePing 
Published: February 2015

SummaryA focal cartilage defect involves tissue loss or rupture. Altered mechanics in the affected joint may play an essential role in the onset and progression of osteoarthritis. The objective of the present study was to determine the compromised load support in the human knee joint during defect progression from the cartilage surface to the cartilage–bone interface. Ten normal and defect cases were simulated with a previously tested 3D finite element model of the knee. The focal defects were considered in both condyles within high load‐bearing regions. Fluid pressurization, anisotropic fibril‐reinforcement, and depth‐dependent mechanical properties were considered for the articular cartilages and menisci. The results showed that a small cartilage defect could cause 25% reduction in the load support of the knee joint due to a reduced capacity of fluid pressurization in the defect cartilage. A partial‐thickness defect could cause a fluid pressure decrease or increase in the remaining underlying cartilage depending on the defect depth. A cartilage defect also increased the shear strain at the cartilage–bone interface, which was more significant with a full‐thickness defect. The effect of cartilage defect on the fluid pressurization also depended on the defect sites and contact conditions. In conclusion, a focal cartilage defect causes a fluid‐pressure dependent load reallocation and a compromised load support in the joint, which depend on the defect depth, site, and contact condition. Copyright © 2015 John Wiley & Sons, Ltd.
Water Soluble CuInSe2 Nanoplates: Controlled Synthesis, Photoelectric Response and Electrocatalytic Reduction of Polysulfides
Authors: Zhu Qi , Chen Wenlong , Dai Fang , Yuan Yanping , Wu Xiangyang , Zai Jiantao , Qi Rongrong , Qian Xuefeng 
Published: February 2015

AbstractHexagonal CuInSe2 (CISe) nanoplates with a size of about 200 nm have been synthesized by a two‐step solvothermal method, in which Sex2− precursor stabilized by HCO(CH3)2NH+ cations (hydrolysis product of the solvent) was prepared from Se powder and vitamin C. Further study indicated that the pre‐reduction process of Se powder could control the concentration of Sex2− ions, which played a key role in the phase formation and morphologies of CISe. Furthermore, poly(vinyl pyrrolidone) was beneficial to form CISe nanoplates and could help CISe nanoplates disperse in ethanol and water to form stable inks. CISe films prepared by drop‐coating showed a good photoelectric response under visible light irradiation and better electrocatalytic activity for the reduction of polysulfides than Pt.
Synthesis, Physicochemical Characterization, and Interaction with DNA of Long‐Alkyl‐Chain Gemini Pyridinium Surfactants
Authors: Barbero Nadia , Magistris Claudio , Quagliotto Pierluigi , Bonandini Luca , Barolo Claudia , Buscaino Roberto , Compari Carlotta , Contardi Laura , Fisicaro Emilia , Viscardi Guido 
Published: February 2015

AbstractPyridinium gemini surfactants with hexadecyl chains linked to nitrogen atoms and a tuned aliphatic spacer that bridges the two pyridinium polar heads in 2,2′‐positions have been synthesized and characterized. A multitechnique approach allowed us to study the aggregation behavior, using conductivity, surface tension, and fluorescence. Graphs of the specific conductivity (κ) versus the surfactant molar concentration (C), and graphs of the molar conductivity (Λ) versus C0.5 suggest pre‐aggregation phenomena of these amphiphiles at very low concentration. The trends of Amin as a function of the spacer length confirm the hypothesis of a conformational change of the molecule with four methylene groups as spacer owing to stacking interactions between the two pyridinium rings mediated by the counterion. Moreover, the trends of Amin and counterion binding (β) suggest that the spacer must be longer than eight carbon atoms to fold efficiently toward the micellar core. The opportunity to tune the surfactant structure and aggregation properties make those surfactants—particularly the long‐chain ones for which the DNA complexing ability was shown by means of atomic force microscopy (AFM) imaging—desirable candidates for gene‐delivery experiments.
High‐Throughput Screening of Thin‐Film Semiconductor Material Libraries I: System Development and Case Study for TiWO
Authors: Sliozberg Kirill , Schäfer Dominik , Erichsen Thomas , Meyer Robert , Khare Chinmay , Ludwig Alfred , Schuhmann Wolfgang 
Published: February 2015

AbstractAn automated optical scanning droplet cell (OSDC) enables high‐throughput quantitative characterization of thin‐film semiconductor material libraries. Photoelectrochemical data on small selected measurement areas are recorded including intensity‐dependent photopotentials and ‐currents, potentiodynamic and potentiostatic photocurrents, as well as photocurrent (action) spectra. The OSDC contains integrated counter and double‐junction reference electrodes and is fixed on a precise positioning system. A Xe lamp with a monochromator is coupled to the cell through a thin poly(methyl methacrylate) (PMMA) optical fiber. A specifically designed polytetrafluoroethylene (PTFE) capillary tip is pressed on the sample surface and defines through its diameter the homogeneously illuminated measurement area. The overall and wavelength‐resolved irradiation intensities and the cell surface area are precisely determined and calibrated. System development and its performance are demonstrated by means of screening of a TiWO thin film.
High‐Throughput Screening of Thin‐Film Semiconductor Material Libraries II: Characterization of FeWO Libraries
Authors: Meyer Robert , Sliozberg Kirill , Khare Chinmay , Schuhmann Wolfgang , Ludwig Alfred 
Published: February 2015

AbstractMetal oxides are promising materials for solar water splitting. To identify suitable materials within the ternary system FeWO, thin‐film material libraries with combined thickness and compositional gradients were synthesized by combinatorial reactive magnetron sputtering. These libraries (>1000 different samples) were investigated by means of structural and functional high‐throughput characterization techniques to establish correlations between composition, crystallinity, morphology, thickness, and photocurrent density in the compositional range between (Fe6W94)Ox and (Fe61W39)Ox. In addition to the well‐known phase WO3, the binary phase W5O14 and the ternary phase Fe2O6W show enhanced photoelectrochemical activity. The highest photocurrent density of 65 μA cm−2 was achieved for the composition (Fe15W85)Ox, which contains the W5O14 phase and has a thickness of 1060 nm.
Highly Efficient Binuclear Ruthenium Catalyst for Water Oxidation
Authors: Sander Anett C. , Maji Somnath , Francàs Laia , Böhnisch Torben , Dechert Sebastian , Llobet Antoni , Meyer Franc 
Published: February 2015

AbstractWater splitting is one of the key steps in the conversion of sunlight into a usable renewable energy carrier such as dihydrogen or more complex chemical fuels. Developing rugged and highly efficient catalysts for the oxidative part of water splitting, the water oxidation reaction generating dioxygen, is a major challenge in the field. Herein, we introduce a new, and rationally designed, pyrazolate‐based diruthenium complex with the highest activity in water oxidation catalysis for binuclear systems reported to date. Single‐crystal X‐ray diffraction showed favorable preorganization of the metal ions, well suited for binding two water molecules at a distance adequate for OO bond formation; redox titrations as well as spectroelectrochemistry allowed characterization of the system in several oxidation states. Low oxidation potentials reflect the trianionic character of the elaborate compartmental pyrazolate ligand furnished with peripheral carboxylate groups. Water oxidation has been mediated both by a chemical oxidant (CeIV)—by means of manometry and a Clark electrode for monitoring the dioxygen production—and electrochemically with impressive activities.
The application of the Johns Hopkins Hospital Template on urine cytology
Authors: Wu Howard H. , Redelman Megan , Chen Shaoxiong , Grignon David J. , Cramer Harvey M. 
Published: February 2015

BackgroundTo evaluate the utility of the Johns Hopkins Hospital (JHH) template in detection of high‐grade urothelial carcinoma (HGUC).MethodsA computerized search of our laboratory information system was performed for all urine cytology cases from 2009 to 2011 processed by the SurePath™. We included only cases with correlating surgical pathology within 6 months after the urinary samples were obtained. The original cytologic diagnoses were reclassified according to the JHH template, and these cytolog ic diagnoses were then correlated with the follow‐up surgical pathology diagnoses.ResultsA total of 273 urine samples with histopathologic follow‐up were identified. The reclassified cytologic diagnoses included negative for urothelial atypia or malignancy (NUAM) 110; atypical urothelial cells of undetermined significance (AUC‐US) 83; atypical urothelial cells, cannot exclude high‐grade urothelial carcinoma (AUC‐H) 49; HGUC 29; and low‐grade urothelial carcinoma (LGUC) 2. More than one‐half of patients (58%) who had biopsy‐confirmed high‐grade urothelial lesions had a preceding cytologic diagnosis of AUC‐H or HGUC. AUC‐H and HGUC are associated with high‐grade urothelial lesions in 80% and 90% of the cases and show statistical significance when compared with AUC‐US or NUAM (P < 0.05).ConclusionThe JHH template is useful and effective in identifying patients with high‐grade urothelial lesions who need to undergo cystoscopy. Diagn. Cytopathol. 2015;43:593–597. © 2015 Wiley Periodicals, Inc.
[Ag{S2CNR(C2H4OH)}] as Single‐Source Precursor for Ag2S – Synthesis, Decomposition Mechanism, and Deposition Studies
Authors: Mothes Robert , Jakob Alexander , Waechtler Thomas , Schulz Stefan E. , Gessner Thomas , Lang Heinrich 
Published: February 2015

AbstractSilver(I) dithiocarbamates [Ag{S2CNR(C2H4OH)}] (3a, R = Me; 3b, R = Bu) were accessible by the reaction of AgNO3 with K{S2CNR(C2H4OH)} (2a, R = Me; 2b, R = Bu). Alternatively, 3b could be prepared by the condensation of CS2 and Ag2O with NHBu(C2H4OH) (1b). The thermal behavior of 3 was studied by thermogravimetric (TG) analysis. A two‐step decomposition process leads to the formation of α‐Ag2S, as evidenced by X‐ray powder diffraction studies. A decomposition mechanism of 3a to form Ag2S through the release of 3‐methyloxazolidine‐2‐thione is discussed based on TG–MS, GC–MS, and NMR experiments. Because of the better solubility of 3b, this complex was tested for Ag2S spin‐coating deposition studies on different substrates (SiO2/Si, TiN/SiO2/Si, glass) with subsequent annealing at 450 °C under a N2 atmosphere. Film thickness, composition, and morphology of the as‐deposited films were determined by XRD, SEM, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy, which showed the formation of 200 nm thick, conformal, adherent, monoclinic α‐Ag2S layers.
Synthesis and Catalytic Activity of Molybdenum–Nitride Complexes Bearing Pincer Ligands
Authors: Kinoshita Eriko , Arashiba Kazuya , Kuriyama Shogo , Eizawa Aya , Nakajima Kazunari , Nishibayashi Yoshiaki 
Published: February 2015

AbstractMolybdenum–nitride complexes bearing pincer ligands have been designed, prepared, and characterized spectroscopically. The synthetic method described in this paper provides a convenient and useful approach to the preparation of cationic molybdenum(V)–nitride complexes that may act as catalysts for the formation of ammonia from molecular dinitrogen under ambient reaction conditions..
A Model Study on Molecular Properties and Mechanistic Investigations of P=C=E14 Molecules
Authors: Li Ming‐Chung , Shih Tsung‐Wei , Li Yu‐Chi , Ma Jia‐Ying , Su Ming‐Der 
Published: February 2015

AbstractThe bonding properties and the potential energy surfaces for the chemical reactions of heteroallenic compounds with a –P=C=E14< pattern are studied by using density functional theory (M06‐2X/Def2‐SVPD). Five Mes*P=C=E14(tBu)Tip species, for which E14 = C, Si, Ge, Sn, and Pb, were used as model reactants in this work. The theoretical evidence shows that Mes*P=C=E14(tBu)Tip molecules have both P=C and C=E14 double bonds. Four types of chemical reaction – water addition, acetylene [3+2] cycloaddition, ketone [2+2] cycloaddition, and selenium [1+2] cycloaddition – have been used to study the reactive activity of these group 14 heteroallenic molecules. This theoretical work predicts that the heavier the group 14 element (E14) in the heteroallenic –P=C=E14< compounds, the smaller is its singlet–triplet energy splitting, the lower is its activation barrier, and the more rapid are its chemical reactions with various chemical species. As a result, this theoretical investigation shows that the relative reactivity of –P=C=E14< increases in the order: –P=C=C<, –P=C=Si<, –P=C=Ge<, –P=C=Sn<, and –P=C=Pb<.
Asymmetric Dihydroxylation of Esters and Amides of Methacrylic, Tiglic, and Angelic Acid: No Exception to the Sharpless Mnemonic!
Authors: Weber Fabian , Brückner Reinhard 
Published: February 2015

AbstractLiterature findings on the facial selectivity of the Sharpless asymmetric dihydroxylation (SAD) of isobutyl angelate are contradictory and partly in conflict with the Sharpless mnemonic. We systematically screened the SAD of esters and amides of angelic, tiglic, and methacrylic acid. Enantiocontrol arose in 14 of the 15 reactions, culminating at 99 % ee for the Weinreb amide of tiglic acid. The absolute configurations of all the nonracemic products were established by (stereo)chemical correlations. Without exception, they conform to the Sharpless mnemonic.
Stable and Easily Handled FeIII Catalysts for Hydrosilylation of Ketones and Aldehydes
Authors: Zhu Kailong , Shaver Michael P. , Thomas Stephen P. 
Published: February 2015

AbstractThe amine–bis(phenolate) iron(III)‐catalysed reduction of ketones and aldehydes to the corresponding secondary and primary alcohols by a consecutive hydrosilylation/hydrolysis process is reported. The amine–bis(phenolate) iron(III) catalyst is easily accessible, stable towards moisture and air and has a broad substrate scope.