bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pockmark formation and evolution in deep water Nigeria: Rapid hydrate growth versus slow hydrate dissolution
Authors: Sultan N. , Bohrmann G. , Ruffine L. , Pape T. , Riboulot V. , Colliat J.‐L. , De Prunelé A. , Dennielou B. , Garziglia S. , Himmler T. , Marsset T. , Peters C.A. , Rabiu A. , Wei J. 
Published: March 2014

AbstractIn previous works, it has been suggested that dissolution of gas hydrate can be responsible for pockmark formation and evolution in deep water Nigeria. It was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas hydrate dynamics. New results obtained by drilling into gas hydrate‐bearing sediments with the MeBo seafloor drill rig in concert with geotechnical in situ measurements and pore water analyses indicate that pockmark formation and evolution in the study area are mainly controlled by rapid hydrate growth opposed to slow hydrate dissolution. On one hand, positive temperature anomalies, free gas trapped in shallow microfractures near the seafloor and coexistence of free gas and gas hydrate indicate rapid hydrate growth. On the other hand, slow hydrate dissolution is evident by low methane concentrations and almost constant sulfate values 2 m above the Gas Hydrate Occurrence Zone.
Associations Between Pressure–Pain Threshold, Symptoms, and Radiographic Knee and Hip Osteoarthritis
Authors: Goode Adam P. , Shi Xiaoyan A. , Gracely Richard H. , Renner Jordan B. , Jordan Joanne M. 
Published: March 2014

ObjectiveTo determine the association between generalized evoked pressure pain sensitivity with distal pressure–pain threshold (PPT) and the presence, severity, or number of involved knee/hip joints with radiographic osteoarthritis (rOA) or related symptoms.MethodsData for these cross‐sectional analyses come from the second followup (2008–11) of the Johnston County Osteoarthritis Project (n = 1,602). PPT measurements were averaged over 2 trials from both the left and right trapezius. Outcomes of radiographic knee and hip OA were both defined by a Kellgren/Lawrence score of 2–4 and site‐specific symptoms were ascertained at clinical interview. Associations were determined with multiple logistic regression models and two‐way interactions were tested at P < 0.05.ResultsThe sample was 67.2% women and 31.0% African American. Participants' mean ± SD age was 67.9 ± 9.0 years, mean ± SD body mass index was 31.5 ± 7.1 kg/m2, mean ± SD Center for Epidemiologic Studies Depression Scale score was 6.5 ± 7.4, and mean ± SD total PPT was 3.6 ± 0.7 kg. Significant associations were found between PPT and self‐reported knee/hip symptoms. No significant associations were found between PPT and presence, severity, or number of joints with knee and hip rOA without accompanying symptoms. No significant interactions were found with demographic or clinical characteristics.ConclusionPPT was significantly associated with self‐reported single and multijoint symptoms. In contrast, after adjustment, PPT measured at the trapezius was not associated with asymptomatic knee or hip rOA. As such, PPT may prove to be a useful indicator of rOA pain processing and of why individuals respond favorably and others do not to treatments targeting rOA.
Incidence and Risk Factors for Thoracic Spine Pain in the Working Population: The French Pays de la Loire Study
Authors: Roquelaure Yves , Bodin Julie , Ha Catherine , Le Marec Fabien , Fouquet Natacha , Ramond‐Roquin Aline , Goldberg Marcel , Descatha Alexis , Petit Audrey , Imbernon Ellen 
Published: March 2014

ObjectiveTo examine the incidence and risk factors for incident thoracic spine pain (TSP) in workers representative of a French region's working population.MethodsIn this prospective study, 3,710 workers were assessed in 2002–2005, and 2,332 (62.9%) of them were reassessed in 2007–2010. TSP was assessed by a self‐administered Nordic questionnaire at baseline and at followup. At baseline, all participants completed a self‐administered questionnaire on personal factors and work exposure. A total of 1,886 subjects (1,124 men and 762 women) without TSP at baseline were eligible for analysis. Associations between incident TSP and risk factors at baseline were analyzed by multivariate logistic regression.ResultsThe incidence rate of TSP was 5.2 (95% confidence interval [95% CI] 3.9–6.6) per 100 men and 10.0 (95% CI 7.8–12.1) per 100 women. TSP was often associated with low back pain and neck pain. TSP in men was associated with age (odds ratios [ORs] ranging from 2.6 [95% CI 0.95–7.1] at 30–39 years to 6.0 [95% CI 2.1–17.3] at ≥50 years), being tall (OR 2.2 [95% CI 1.2–3.9]), frequent/sustained trunk bending (OR 3.0 [95% CI 1.5–6.1]), lack of recovery period or change in the task (OR 2.0 [95% CI 1.2–3.6]), and driving vehicles (OR 2.8 [95% CI 1.4–5.5]). Being overweight or obese was associated with lower risk (OR 0.5 [95% CI 0.3–0.96]). TSP in women was associated with high perceived physical workload (OR 1.9 [95% CI 1.1–3.3]), after adjustment for confounding variables.ConclusionThe risk model of TSP combined personal and work‐related organizational and physical factors. Trunk bending appeared to be a strong independent predictor of TSP in this working population.
Magnetically Retrievable Nano Crystalline Nickel Ferrite‐ Catalyzed Aerobic, Ligand‐Free CN, CO and CC Cross‐ Coupling Reactions for the Synthesis of a Diversified Library of Heterocyclic Molecules
Authors: Paul Sanjay , Pradhan Koyel , Ghosh Sirshendu , De S. K. , Das Asish R. 
Published: March 2014

AbstractA new nickel ferrite nano‐crystal‐catalyzed, ligand‐free strategy for the construction of CN, CO, and CC bonds is presented, in which easily available nitrogen and oxygen nucleophiles, aryl/heteroaryl halides and arylboronic acids are used for the cross‐coupling reactions. The reactions can be performed at low catalyst loadings with excellent functional group tolerance and chemoselectivity. A variety of functional groups are compatible with the reaction conditions, including nitro, methoxy, as well as acid‐ and base‐sensitive heteroaromatic groups. This unprecedented chemistry nicely complements classical methods for the N‐arylation of amines/heteroamines, the O‐arylation of phenols/hydroxycoumarins and biaryl/heteroaryl synthesis. The low cost, easy to handle nature and the simplicity of this catalytic system render the method competitive with comparable copper‐ and palladium‐based protocols which require the presence of sophisticated ligands. Nickel ferrite magnetic nanoparticles were prepared by a simple hydrothermal method and characterized by using XRD, TEM image, energy dispersive X‐ray analysis, XPS and FT‐IR. The easy recovery of the catalyst and high yield of the products make the protocol attractive, sustainable and economic. The catalyst was reused for five cycles with almost unaltered catalytic activity.magnified image
Synthesis of Furanose Spirooxindoles via 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU)‐Catalyzed Aldol Reactions of a Pyruvic Aldehyde Derivative
Authors: Zhang Dongxin , Johnson Sherida , Cui Hai‐Lei , Tanaka Fujie 
Published: March 2014

AbstractSpirooxindoles are important compounds as they are often found in bioactive molecules. Thus, the development of new spirooxindoles and of synthetic routes to spirooxindoles is a great interest to discover new biofunctional molecules and therapeutic leads. We developed a concise method for the synthesis of spirooxindoles bearing a furanose unit. 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU) was used for an aldol reaction of a pyruvic aldehyde derivative with isatin; reduction of the ketone group was followed by treatment with acid to generate the spirofuranose unit. A set of furanose spirooxindoles were obtained in good to high yields.
Development of a Peptide‐Based Primary Aminocatalyst with a Helical Structure
Authors: Akagawa Kengo , Suzuki Rieko , Kudo Kazuaki 
Published: March 2014

AbstractA resin‐supported peptide with an N‐terminal primary amino group was developed as a primary aminocatalyst and used in the asymmetric Michael addition of nitromethane to α,β‐unsaturated ketones. These peptides with helical motifs, that is, polyleucine and a repeated Leu‐Leu‐Aib (Aib=2‐aminoisobutyric acid) sequence, efficiently catalyzed the reaction. The introduction of two tryptophan residues at the N‐terminus of the helical peptides improved the enantioselectivity of the reaction, and using the catalysts in aqueous media enhanced the reaction rate. The versatility of the optimum catalyst with the (Trp)2‐(Leu‐Leu‐Aib)3 sequence was demonstrated by applying it to other organocatalytic reactions such as the Michael addition of malonates to α,β‐unsaturated ketones and a three‐component, sequential reaction with methacrolein.
Ruthenium(V) Oxides from Low‐Temperature Hydrothermal Synthesis
Authors: Hiley Craig I. , Lees Martin R. , Fisher Janet M. , Thompsett David , Agrestini Stefano , Smith Ronald I. , Walton Richard I. 
Published: March 2014

AbstractLow‐temperature (200 °C) hydrothermal synthesis of the ruthenium oxides Ca1.5Ru2O7, SrRu2O6, and Ba2Ru3O9(OH) is reported. Ca1.5Ru2O7 is a defective pyrochlore containing RuV/VI; SrRu2O6 is a layered RuV oxide with a PbSb2O6 structure, whilst Ba2Ru3O9(OH) has a previously unreported structure type with orthorhombic symmetry solved from synchrotron X‐ray and neutron powder diffraction. SrRu2O6 exhibits unusually high‐temperature magnetic order, with antiferromagnetism persisting to at least 500 K, and refinement using room temperature neutron powder diffraction data provides the magnetic structure. All three ruthenates are metastable and readily collapse to mixtures of other oxides upon heating in air at temperatures around 300–500 °C, suggesting they would be difficult, if not impossible, to isolate under conventional high‐temperature solid‐state synthesis conditions.
Stereoselektive Metall‐freie Synthese von β‐Aminothioestern mit tertiären und quartären Stereozentren
Authors: Bahlinger Annette , Fritz Sven P. , Wennemers Helma 
Published: March 2014

Abstractβ‐Aminothioester sind wichtige Bausteine für die Synthese bioaktiver Moleküle. Hier wurden organokatalytische Mannich‐Reaktionen entwickelt, die direkten und stereoselektiven Zugang zu β2‐ und β2,3,3‐Aminothioestern ausgehend von simplen Bausteinen bieten. Mechanistische Untersuchungen zeigen, dass der stereochemische Verlauf der Reaktion durch die Wahl des Substrates kontrolliert wird. Die linearen Produkte, die benachbarte tertiäre und quartäre Stereozentren enthalten, konnten durch stereoselektive Decarboxylierung und Entschützung weiter zu β2,3‐Bausteinen funktionalisiert werden. Außerdem demonstrieren wir den großen präparativen Wert der β‐Aminothioester durch die Anwendung in einer Kupplungsreagens‐freien Peptidsynthese.
On‐Chip Spyhole Mass Spectrometry for Droplet‐Based Microfluidics
Authors: Gasilova Natalia , Yu Qiuliyang , Qiao Liang , Girault Hubert H. 
Published: March 2014

AbstractFor efficient coupling of droplet‐based microfluidics with mass spectrometry (MS), a spyhole drilled on the top of a microchip is used to sample the passing droplets by electrostatic‐spray ionization (ESTASI) MS. The technique involves placing an electrode below the chip under the spyhole and applying high‐voltage pulses. Electrospray occurs directly from the spyhole, and the droplet content is analyzed by MS without a dilution or oil removal step. To demonstrate the versatility of this technique, we have successfully monitored a droplet‐based tryptic digestion, as well as a biphasic reaction between β‐lactoglobulin in water and α‐tocopheryl acetate in 1,2‐dichloroethane, where the protein extracts the antioxidant from the oil phase and becomes reduced.
Ein flüchtiges Lacton aus Hymenoscyphus pseudoalbidus, dem Pathogen der Europäischen Esche, inhibiert die Keimung seines Wirtes
Authors: Citron Christian A. , Junker Corina , Schulz Barbara , Dickschat Jeroen S. 
Published: March 2014

AbstractDer weitgehend unbekannte Sekundärmetabolismus des phytopathogenen Pilzes Hymenoscyphus pseudoalbidus wurde mittels der CLSA‐Methode untersucht. Eine Serie flüchtiger Lactone wurde per GC/MS identifiziert. Die Lactone wurden synthetisiert und in einem Bioaktivitätstest eingesetzt, in dem eine der Verbindungen als starker Keimungsinhibitor gegenüber Eschensamen auffiel. Diese Verbindung verursachte überdies Nekrosen im pflanzlichen Gewebe.
Axially Chiral Imidodiphosphoric Acid Catalyst for Asymmetric Sulfoxidation Reaction: Insights on Asymmetric Induction
Authors: Jindal Garima , Sunoj Raghavan B. 
Published: March 2014

AbstractInsights into chiral induction for an asymmetric sulfoxidation reaction involving a single oxygen atom transfer are gained through analyzing the stereocontrolling transition states. The fitting of the substrate into the chiral cavity of a new class of imidodiphosphoric Brønsted acids, as well as weak CH⋅⋅⋅π and CH⋅⋅⋅O noncovalent interactions, are identified as responsible for the observed chiral induction.
cis‐Specific Hydrofluorination of Alkenylarenes under Palladium Catalysis through an Ionic Pathway
Authors: Emer Enrico , Pfeifer Lukas , Brown John M. , Gouverneur Véronique 
Published: March 2014

AbstractThis paper describes the hydrofluorination of alkenes through sequential H− and F+ addition under palladium catalysis. The reaction is cis specific, thus providing access to benzylic fluorides. The mechanism of this reaction involves an ionic pathway and is distinct from known hydrofluorinations involving radical intermediates. The first catalytic enantioselective hydrofluorination is also disclosed.
Lamellar‐Twisting‐Induced Circular Dichroism of Chromophore Moieties in Banded Spherulites with Evolution of Homochirality
Authors: Li Ming‐Chia , Wang Hsiao‐Fang , Chiang Chen‐Hung , Lee Yu‐Der , Ho Rong‐Ming 
Published: March 2014

AbstractBanded spherulites are formed by crystallization of a chiral polymer that is end‐capped with chromophore. Induced circular dichroism (ICD) of the chromophore can be found in the crystallized chiral polymers, giving exclusive optical response of the ICD. The ICD signals are presumed to be driven by the lamellar twisting in the crystalline spherulites, and the exclusive optical activity is attributed to the chirality transfer from molecular level to macroscopic level. To verify the suggested mechanism, the sense of the lamellar twisting in the crystalline spherulite is determined using PLM for the comparison with the ICD signals of the chromophore in the electron circular dichroism spectrum. The conformational chirality of the chiral polymer is determined by the vibrational circular dichroism spectrum. On the basis of the chiroptical results, evolution of homochirality from helical polymer chains (conformational chirality) to lamellar twisting in the banded spherulite (hierachical chirality) is suggested.
Stereoselective Metal‐Free Synthesis of β‐Amino Thioesters with Tertiary and Quaternary Stereogenic Centers
Authors: Bahlinger Annette , Fritz Sven P. , Wennemers Helma 
Published: March 2014

Abstractβ‐Amino thioesters are important natural building blocks for the synthesis of numerous bioactive molecules. An organocatalyzed Mannich reaction was developed which provides direct and highly stereoselective access to acyclic β2‐ and β2,3,3‐amino thioesters with adjacent tertiary and quaternary stereocenters. Mechanistic studies showed that the stereochemical course of the reaction can be controlled by the choice of the substrates. The β‐amino thioesters were further functionalized by, for example, stereoselective decarboxylation to access β2,3‐frameworks. In addition, the value of the β‐amino thioesters was shown in coupling‐reagent‐free peptide synthesis.
Total Chemical Synthesis and Biological Activities of Glycosylated and Non‐Glycosylated Forms of the Chemokines CCL1 and Ser‐CCL1
Authors: Okamoto Ryo , Mandal Kalyaneswar , Ling Morris , Luster Andrew D. , Kajihara Yasuhiro , Kent Stephen B. H. 
Published: March 2014

AbstractCCL1 is a naturally glycosylated chemokine protein that is secreted by activated T‐cells and acts as a chemoattractant for monocytes.1 Originally, CCL1 was identified as a 73 amino acid protein having one N‐glycosylation site,1 and a variant 74 residue non‐glycosylated form, Ser‐CCL1, has also been described.2 There are no systematic studies of the effect of glycosylation on the biological activities of either CCL1 or Ser‐CCL1. Here we report the total chemical syntheses of both N‐glycosylated and non‐glycosylated forms of (Ser‐)CCL1, by convergent native chemical ligation. We used an N‐glycan isolated from hen egg yolk together with the Nbz linker for Fmoc chemistry solid phase synthesis of the glycopeptide‐αthioester building block.3 Chemotaxis assays of these glycoproteins and the corresponding non‐glycosylated proteins were carried out. The results were correlated with the chemical structures of the (glyco)protein molecules. To the best of our knowledge, these are the first investigations of the effect of glycosylation on the chemotactic activity of the chemokine (Ser‐)CCL1 using homogeneous N‐glycosylated protein molecules of defined covalent structure.
The Bioinorganic Chemistry of Apoptosis: Potential Inhibitory Zinc Binding Sites in Caspase‐3
Authors: Daniel A. Gerard , Peterson Erica J. , Farrell Nicholas P. 
Published: March 2014

AbstractZn2+ inhibits the action of several of the caspases and thus may act as a regulator of apoptosis. Reversal of this inhibition is one possible approach for the development of apoptosis‐based therapies. Few studies describe the molecular details of the Zn2+–caspase interaction, the understanding of which is essential for the success of any therapeutic strategies. Enzyme kinetics and biophysical studies have shown that the inhibition is of mixed type with prominent (ca. 60 % of inhibition) uncompetitive characteristics and an IC50 of 0.8 μM under the conditions used. Fluorescence‐based techniques confirmed that, during inhibition in the sub‐micromolar range, substrate binding remains unaffected. A new zinc binding site composed of the catalytic histidine and a nearby methionine residue, rather than the catalytic histidine and cysteine dyad, is proposed based on the experimental observations. DFT models were used to demonstrate that the proposed site could be the preferred inhibitory zinc binding site.
Synthesis of 7,8‐Dehydropurpurin Dimers and Their Conversion into Conformationally Constrained β‐to‐β Vinylene‐Bridged Porphyrin Dimers
Authors: Fukui Norihito , Yorimitsu Hideki , Lim Jong Min , Kim Dongho , Osuka Atsuhiro 
Published: March 2014

Abstract7,8‐Dehydropurpurin has attracted much attention owing to the dual 18π‐ and 20π‐electron circuits in its macrocyclic conjugation. The two‐fold Pd‐catalyzed [3+2] annulation of meso‐bromoporphyrin with 1,4‐diphenylbutadiyne furnished 7,8‐dehydropurpurin dimers. The 8a,8a‐linked dimer displays a red‐shifted and enhanced absorption band in the NIR region and a small electrochemical HOMO–LUMO band gap as a consequence of efficient conjugation between the two coplanar 7,8‐dehydropurpurin units. Treatment of this dimer with N‐bromosuccinimide in chloroform and ethanol gave β‐to‐β vinylene‐bridged porphyrin dimers. Owing to the highly constrained conformations, these dimers exhibit perturbed absorption spectra, small Stokes shifts, and high fluorescence quantum yields.
The kinetics of poly(butylene succinate) synthesis and the influence of molar mass on its thermal properties
Authors: Garin Matthieu , Tighzert Lan , Vroman Isabelle , Marinkovic Sinisa , Estrine Boris 
Published: March 2014

ABSTRACTThe synthesis of poly(butylene succinate) (PBS) of Mw ranging from 4000 to 180,000 g mol−1 is realized with molar ratios [COOH]0/[OH]0 of 1 and 0.98, and varying amounts of titanium (IV) tetrabutoxide (TBT) catalyst. Polycondensation kinetics are followed by chemical titration of carboxylic groups, and the kinetic rate constants of self‐catalyzed and external‐catalyzed reactions are calculated. The synthesis of PBS with high molar mass follows the classical Flory theory. The effect of molar mass on PBS thermal properties is also studied. A faster crystallization rate and a higher temperature of crystallization are observed, for very high molar masses. This behavior could be due to a memory effect of the polymer. Complex melting behavior of PBS is induced by a continuous reorganization of the crystalline phase, as observed by MTDSC. DSC measurements also reveal that the crystallinity—and so the amorphous phase—is limited to about 35% when the molar mass Mn is higher than 40,000 g mol−1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40639.
Intravenous Immunoglobulin Attenuates Experimental Autoimmune Arthritis by Inducing Reciprocal Regulation of Th17 and Treg Cells in an Interleukin‐10–Dependent Manner
Authors: Lee Seon‐Yeong , Jung Young‐Ok , Ryu Jun‐Geol , Kang Chang‐Min , Kim Eun‐Kyung , Son Hye‐Jin , Yang Eun‐Ji , Ju Ji‐Hyeon , Kang Young‐Sun , Park Sung‐Hwan , Kim Ho‐Youn , Cho Mi‐La 
Published: March 2014

ObjectiveIntravenous immunoglobulin (IVIG) is used as a therapeutic agent in various autoimmune diseases. The aims of this study were to investigate the therapeutic effects of IVIG on collagen‐induced arthritis (CIA) and identify the mechanism responsible for any therapeutic effects.MethodsIVIG was administered to mice with CIA, and the in vivo effects were determined. Th17 and Treg cell frequencies were analyzed by flow cytometry, and cytokine levels in the supernatant were measured by enzyme‐linked immunosorbent assay. Subpopulations of T cells and B cells in the spleen were assessed by confocal microscopy.ResultsThe arthritis severity score and incidence of arthritis were lower in mice treated with IVIG compared with untreated mice. Histopathologic analysis showed less joint damage in mice treated with IVIG. The expression of proinflammatory cytokines, specific type II collagen antibodies, and osteoclast markers was significantly reduced in mice treated with IVIG. Administration of IVIG induced increased FoxP3 expression and inhibited Th17 cell development. The number of FoxP3+ Treg cells was increased, and the number of Th17 cells was decreased in the spleens of mice treated with IVIG. The number of FoxP3+ follicular helper T cells was increased, and subsequent maturation of germinal center B cells was inhibited by IVIG. In addition, IVIG up‐regulated interleukin‐10 (IL‐10) and Fcγ receptor IIB expression. The treatment effects of IVIG on arthritis were lost in IL‐10–knockout mice.ConclusionThese results showed that IVIG has therapeutic effects by modulating CD4+ T cell differentiation. The therapeutic effects of IVIG are dependent on IL‐10.
Visible‐Light‐Induced Generation of H2 by Nanocomposites of Few‐Layer TiS2 and TaS2 with CdS Nanoparticles
Authors: Gupta Uttam , Rao Bolla Govinda , Maitra Urmimala , Prasad B. E. , Rao C. N. R. 
Published: March 2014

AbstractGraphene analogues of TaS2 and TiS2 (3–4 layers), prepared by Li intercalation followed by exfoliation in water, were characterized. Nanocomposites of CdS with few‐layer TiS2 and TaS2 were employed for the visible‐light‐induced H2 evolution reaction (HER). Benzyl alcohol was used as the sacrificial electron donor, which was oxidized to benzaldehyde during the reaction. Few‐layer TiS2 is a semiconductor with a band gap of 0.7 eV, and its nanocomposite with CdS showed an activity of 1000 μmol h−1 g−1. The nanocomposite of few‐layer TaS2, in contrast, gave rise to higher activity of 2320 μmol h−1 g−1, which was attributed to the metallic nature of few‐layer TaS2. The amount of hydrogen evolved after 20 and 16 h for the CdS/TiS2 and CdS/TaS2 nanocomposites was 14833 and 28132 μmol, respectively, with turnover frequencies of 0.24 and 0.57 h−1, respectively.