bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kationische Ketten von Phosphanyl‐ und Arsanylboranen
Authors: Marquardt Christian , Thoms Christine , Stauber Andreas , Balázs Gábor , Bodensteiner Michael , Scheer Manfred 
Published: March 2014

AbstractWährend catena‐Phosphorkationen innerhalb der letzten Jahre intensiv untersucht wurden, gab es über gemischte kationische Ketten aus Gruppe‐13‐ und Gruppe‐15‐Elementen bislang keine Berichte. Die Umsetzung der Pnictogenborane H2EBH2⋅NMe3 (E=P, As) mit Monohalogenboranen führt zu den kationischen Kettenverbindungen [Me3N⋅BH2EH2BH2⋅NMe3][X] (E=P, As; X=AlCl4, I) und [Me3N⋅BH2PH2BH2PH2BH2⋅NMe3][X] (X=I, VCl4(thf)2). Alle Verbindungen wurden durch Röntgenstrukturanalyse, NMR‐Spektroskopie, IR‐Spektroskopie und Massenspektrometrie charakterisiert. DFT‐Rechnungen erklären den Reaktionsverlauf, die hohe thermodynamische Stabilität und die Ladungsverteilung innerhalb der Kette und bestätigen die beobachteten Festkörperstrukturen.
Eine Brønsted‐Säure‐katalysierte Redox‐Arylierung
Authors: Peng Bo , Huang Xueliang , Xie Lan‐Gui , Maulide Nuno 
Published: March 2014

AbstractEs wird eine Brønsted‐Säure‐katalysierte Redox‐Arylierung von Inamiden mit Arylsulfoxiden als Arylierungsreagentien vorgestellt. Diese metallfreie Umwandlung läuft bei Raumtemperatur ab, und liefert auf redoxneutralem und atomökonomischem Wege α‐arylierte Oxazolidinone.
Cytochrome P450 Catalyzed Oxidative Hydroxylation of Achiral Organic Compounds with Simultaneous Creation of Two Chirality Centers in a Single CH Activation Step
Authors: Roiban Gheorghe‐Doru , Agudo Rubén , Reetz Manfred T. 
Published: March 2014

AbstractRegio‐ and stereoselective oxidative hydroxylation of achiral or chiral organic compounds mediated by synthetic reagents, catalysts, or enzymes generally leads to the formation of one new chiral center that appears in the respective enantiomeric or diastereomeric alcohols. By contrast, when subjecting appropriate achiral compounds to this type of CH activation, the simultaneous creation of two chiral centers with a defined relative and absolute configuration may result, provided that control of the regio‐, diastereo‐, and enantioselectivity is ensured. The present study demonstrates that such control is possible by using wild type or mutant forms of the monooxygenase cytochrome P450 BM3 as catalysts in the oxidative hydroxylation of methylcyclohexane and seven other monosubstituted cyclohexane derivatives.
Towards True Carbaporphyrinoids: Synthesis of 21‐Carba‐23‐thiaporphyrin
Authors: Berlicka Anna , Dutka Paweł , Szterenberg Ludmiła , Latos‐Grażyński Lechosław 
Published: March 2014

AbstractIn the search for porphyrinoids with a built‐in cyclopentadienyl moiety (true carbaporphyrins), a rational synthesis of carbathiaporphyrin, the synthons, has been elaborated. The donors (C,N,S,N) in the porphyrinic core of carbathiaporphyrinoids are potentially of fundamental importance for generating organometallic complexes, as exemplified through formation of the palladium(II) complex.
Rhodium Enalcarbenoids: Direct Synthesis of Indoles by Rhodium(II)‐Catalyzed [4+2] Benzannulation of Pyrroles
Authors: Dawande Sudam Ganpat , Kanchupalli Vinaykumar , Kalepu Jagadeesh , Chennamsetti Haribabu , Lad Bapurao Sudam , Katukojvala Sreenivas 
Published: March 2014

AbstractDisclosed herein is the design of an unprecedented electrophilic rhodium enalcarbenoid which results from rhodium(II)‐catalyzed decomposition of a new class of enaldiazo compounds. The synthetic utility of these enalcarbenoids has been successfully demonstrated in the first transition‐metal‐catalyzed [4+2] benzannulation of pyrroles, thus leading to substituted indoles. The new benzannulation has been applied to the efficient synthesis of the natural product leiocarpone as well as a potent adipocyte fatty‐acid binding protein inhibitor.
Formation of NixCo3−xS4 Hollow Nanoprisms with Enhanced Pseudocapacitive Properties
Authors: Yu Le , Zhang Lei , Wu Hao Bin , Lou Xiong Wen (David) 
Published: March 2014

AbstractHollow nanostructures are of great interest for a wide variety of applications. Despite the great advances, synthesis of anisotropic hollow structures is still very challenging. In this work, we have developed a simple sacrificial template method to synthesize uniform NixCo3−xS4 hollow nanoprisms with tunable composition. Tetragonal nanoprisms of nickel–cobalt acetate hydroxide precursors with controllable Ni/Co molar ratios are first synthesized and used as the sacrificial templates. After a sulfidation process with thioacetamide (TAA) in ethanol, the solid precursor prisms can be transformed into the corresponding NixCo3−xS4 hollow nanoprisms with a well‐defined hollow interior. The intriguing structural and compositional features are beneficial for electrochemical applications. Impressively, the resultant NixCo3−xS4 hollow prisms manifest a high specific capacitance with enhanced cycling stability, making them potential electrode materials for supercapacitors.
Stabilization of a Diphosphagermylene through pπ–pπ Interactions with a Trigonal‐Planar Phosphorus Center
Authors: Izod Keith , Rayner Daniel G. , El‐Hamruni Salima M. , Harrington Ross W. , Baisch Ulrich 
Published: March 2014

AbstractN‐Heterocyclic carbenes and their heavier homologues are, in part, stabilized by delocalization of the N lone pairs into the vacant p‐orbital at carbon (or a heavier Group 14 element center). These interactions are usually absent in the corresponding P‐substituted species, owing to the large barrier to planarization of phosphorus. However, judicious selection of the substituents at phosphorus has enabled the synthesis of a diphosphagermylene, [(Dipp)2P]2Ge, in which one of the P centers is planar (Dipp=2,6‐diisopropylphenyl). The planar nature of this P center and the correspondingly short PGe distance suggest a significant degree of PGe multiple bond character that is due to delocalization of the phosphorus lone pair into the vacant p‐orbital at germanium. DFT calculations support this proposition and NBO and AIM analyses are consistent with a GeP bond order greater than unity.
Tuning Mechanism‐Based Inactivators of Neuraminidases: Mechanistic and Structural Insights
Authors: Buchini Sabrina , Gallat François‐Xavier , Greig Ian R. , Kim Jin‐Hyo , Wakatsuki Soichi , Chavas Leonard M. G. , Withers Stephen G. 
Published: March 2014

Abstract3‐Fluorosialosyl fluorides are inhibitors of sialidases that function by the formation of a long‐lived covalent active‐site adduct and have potential as therapeutics if made specific for the pathogen sialidase. Surprisingly, human Neu2 and the Trypanosoma cruzi trans‐sialidase are inactivated more rapidly by the reagent with an equatorial fluorine at C3 than by its axial epimer, with reactivation following the same pattern. To explore a possible stereoelectronic basis for this, rate constants for spontaneous hydrolysis of the full series of four 3‐fluorosialosyl fluorides were measured, and ground‐state energies for each computed. The alpha (equatorial) anomeric fluorides hydrolyze more rapidly than their beta anomers, consistent with their higher ground‐state energies. However ground‐state energies do not explain the relative spontaneous reactivities of the 3‐fluoro‐epimers. The three‐dimensional structures of the two 3‐fluoro‐sialosyl enzyme intermediates of human Neu2 were solved, revealing key stabilizing interactions between Arg21 and the equatorial, but not the axial, fluorine. Because of changes in geometry these interactions will increase at the transition state, likely explaining the difference in reaction rates.
Harnessing the Evolvability of Tricyclic Microviridins To Dissect Protease–Inhibitor Interactions
Authors: Weiz Annika R. , Ishida Keishi , Quitterer Felix , Meyer Sabine , Kehr Jan‐Christoph , Müller Kristian M. , Groll Michael , Hertweck Christian , Dittmann Elke 
Published: March 2014

AbstractUnderstanding and controlling proteolysis is an important goal in therapeutic chemistry. Among the natural products specifically inhibiting proteases microviridins are particularly noteworthy. Microviridins are ribosomally produced and posttranslationally modified peptides that are processed into a unique, cagelike architecture. Here, we report a combined rational and random mutagenesis approach that provides fundamental insights into selectivity‐conferring moieties of microviridins. The potent variant microviridin J was co‐crystallized with trypsin, and for the first time the three‐dimensional structure of microviridins was determined and the mode of inhibition revealed.
A Brønsted Acid Catalyzed Redox Arylation
Authors: Peng Bo , Huang Xueliang , Xie Lan‐Gui , Maulide Nuno 
Published: March 2014

AbstractA Brønsted acid catalyzed redox arylation of ynamides that employs aryl sulfoxides as the arylating agents is reported. This metal‐free transformation proceeds at room temperature and efficiently affords α‐arylated oxazolidinones in a redox‐neutral, atom‐economic fashion.
A CFD modeling of the gas–solid two‐phase flow in an FCC riser under the electrostatic conditions
Authors: Jiang Li , Fang‐Zhi Xiao , Zheng‐Hong Luo 
Published: March 2014

ABSTRACTElectrostatics is an inevitable phenomenon in fluidization processes and granular flow, where collisions between particulates and walls with different materials occur. In this work, a two‐dimensional computational fluid dynamics model based on the Eulerian–Eulerian approach was applied and coupled with a first‐principles electrostatic model to describe the gas–solid two‐phase flow behavior in a fluid catalytic cracking (FCC) riser reactor under the electrostatic conditions. The coupled model was used to predict the main gas–solid flow distribution parameters in the FCC riser, such as electric potential, particle volume fraction, gas‐phase temperature, and gas‐phase component fractions. The simulation results showed that the electrostatic had a significant influence on the particle distribution in the bottom dense region of the FCC riser, whereas it had a weak influence in the upper dilute region at the cold‐flow conditions. The simulation results also showed that the electrostatic had a weak influence on the particle concentration, gas‐phase temperature, and lump concentration distributions when the cracking reaction was considered. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Influence of alumina content and thermal treatment on the thermal conductivity of UPE/Al2O3 composite
Authors: Wu Xinfeng , Jiang Pingkai , Zhou Yun , Yu Jinhong , Zhang Fuhua , Dong Lihua , Yin Yansheng 
Published: March 2014

ABSTRACTUltra high molecular weight polyethylene/alumina (UPE/Al2O3) microcomposites with high loading micro alumina (Al2O3, 20 to 100 phr) were prepared by casting method. The composites were thermal treated (cooled slowly) and then the thermal properties were studied at temperatures from 25 to 125°C. Thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) proves the homodispersion of Al2O3 microparticles in UPE. TGA indicates that the temperature of 5% weight loss of UPE/Al2O3 (100 phr) composite is 467.0°C, 10.5°C higher than that of pure UPE. Differential scanning calorimetry (DSC) shows that the melting point and the real degree of crystal (Xrc) of treated UPE/Al2O3 composite (100 phr) are 141.4°C and 65.7%, respectively, all higher than that of untreated composite, which can be described by crystal bridge mechanism. The density of the composite is also be enhanced because of crystal volume shrinkage induced by thermal treatment. The thermal conductivity of the treated UPE/Al2O3 composite (100 phr) is 1.920 W (m K)−1 at 25°C, 23.6% higher than that of the untreated composite. Crystal bridge thermal conduction mechanism is proposed. The thermal conductivity of UPE/Al2O3 composite has some dependency on the increasing Al2O3 content and also thermal treatment. These results can give some advice to design formulations for practical applications in pipe area and other wear area. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40528.
A Comparison of the Malignancy Incidence Among Patients With Psoriatic Arthritis and Patients With Rheumatoid Arthritis in a Large US Cohort
Authors: Gross Rachael L. , Schwartzman‐Morris Julie S. , Krathen Michael , Reed George , Chang Hong , Saunders Katherine C. , Fisher Mark C. , Greenberg Jeffrey D. , Putterman Chaim , Mease Philip J. , Gottlieb Alice B. , Kremer Joel M. , Broder Anna 
Published: March 2014

ObjectiveTo compare the incidence rates of malignancy among patients with psoriatic arthritis (PsA) and patients with rheumatoid arthritis (RA) in the Consortium of Rheumatology Researchers of North America (CORRONA) registry.MethodsWe analyzed 2,970 patients with PsA (7,133 patient‐years of followup) and 19,260 patients with RA (53,864 patient‐years of followup). Using a standardized adjudication process, we identified 40 confirmed malignancies in the patients with PsA and 307 confirmed malignancies in those with RA. Incidence rates were calculated per 100 patient‐years. Incidence rate ratios were estimated, with adjustment for age, sex, disease duration, body mass index, disease activity, year of enrollment, and medication use.ResultsThe overall malignancy incidence per 100 patient‐years was similar between patients with PsA and patients with RA (0.56 [95% confidence interval (95% CI) 0.40−0.76] and 0.56 [95% CI 0.50−0.63], respectively). Nonmelanoma skin cancer was the most common type of cancer in the overall cohort, with an incidence rate of 0.21 (95% CI 0.12−0.35) in PsA, and 0.20 (95% CI 0.17−0.24) in RA, with a calculated incidence rate ratio of 1.05 (95% CI 0.61−1.80; P = 0.85). Lymphoma rates were similar in PsA and RA (0.04 [95% CI 0.01−0.12] and 0.04 [95% CI 0.02−0.06], respectively; incidence rate ratio 1.00 [95% CI 0.17−3.11]; P = 0.67). The adjusted incidence rate ratio of malignancy in PsA versus RA was 1.17 (95% CI 0.82−1.69; P = 0.37).ConclusionThe incidence rates across malignancy subtypes were similar in the PsA and RA cohorts from a US registry.
Prediction of Pulmonary Complications and Long‐Term Survival in Systemic Sclerosis
Authors: Nihtyanova Svetlana I. , Schreiber Benjamin E. , Ong Voon H. , Rosenberg Daniel , Moinzadeh Pia , Coghlan J. Gerrard , Wells Athol U. , Denton Christopher P. 
Published: March 2014

ObjectiveTo assess survival and incidence of organ‐based complications in a large single‐center cohort of unselected systemic sclerosis (SSc) patients, and to explore predictors of survival and clinically significant pulmonary fibrosis (PF) and pulmonary hypertension (PH).MethodsThe study cohort consisted of 398 consecutive SSc patients, followed up for up to 15 years. Cox proportional hazards analysis with demographic, clinical, and laboratory characteristics as predictor variables was used to develop prediction models for pulmonary complications and survival.ResultsThe overall survival estimate at the end of followup was 57% among patients with limited cutaneous SSc (lcSSc) and 50% among patients with diffuse cutaneous SSc (dcSSc) (P = 0.017). We found that greater age at disease onset, dcSSc, lower diffusing capacity for carbon monoxide (DLco), lower hemoglobin levels, higher serum creatinine levels, and the presence of PH or cardiac involvement were independent predictors of worse survival. Over the entire followup period, 42% of dcSSc patients and 22% of lcSSc patients developed clinically significant PF (P < 0.001). The variables that predicted clinically significant PF development were dcSSc, greater age at onset, lower forced vital capacity and DLco, and the presence of anti–topoisomerase I antibody, while the presence of anticentromere antibody was protective. There was no difference in cumulative incidence of PH between the 2 subsets—24% in lcSSc and 18% in dcSSc (P = 0.558). Incidence rates were 1–2% per year. The PH prediction model demonstrated that greater age at onset, increase in serum creatinine levels, lower DLco, and the presence of anti–RNA polymerase III or anti–U3 RNP antibodies were associated with increased risk of PH, while anti–topoisomerase I antibody positivity reduced the hazard.ConclusionOur study provides data on long‐term outcome of SSc and the timing and frequency of major organ complications. The predictive models we present could be used as clinical tools for patient risk stratification and could facilitate cohort enrichment for event‐driven studies.
Palmitate Has Proapoptotic and Proinflammatory Effects on Articular Cartilage and Synergizes With Interleukin‐1
Authors: Alvarez‐Garcia Oscar , Rogers Nicole H. , Smith Roy G. , Lotz Martin K. 
Published: March 2014

ObjectiveObesity is a major risk factor for the development of osteoarthritis (OA) that is associated with a state of low‐grade inflammation and increased circulating levels of adipokines and free fatty acids (FFAs). The aim of this study was to analyze the effects of saturated (palmitate) and monounsaturated (oleate) FFAs on articular chondrocytes, synoviocytes, and cartilage.MethodsHuman articular chondrocytes and fibroblast‐like synoviocytes obtained from young healthy donors and OA chondrocytes from patients undergoing total knee replacement surgery were treated with palmitate or oleate alone or in combination with interleukin‐1β (IL‐1β). Cell viability, caspase activation, and gene expression of proinflammatory factors, extracellular matrix (ECM) proteins, and proteases were studied. In addition, chondrocyte viability, IL‐6 production, and matrix damage were assessed in bovine and human articular cartilage explants cultured with FFAs in the presence or absence of IL‐1β.ResultsPalmitate, but not oleate, induced caspase activation and cell death in IL‐1β–stimulated normal chondrocytes, and up‐regulated the expression of IL‐6 and cyclooxygenase 2 in chondrocytes and fibroblast‐like synoviocytes through Toll‐like receptor 4 (TLR‐4) signaling. In cartilage explants, palmitate induced chondrocyte death, IL‐6 release, and ECM degradation. Palmitate synergized with IL‐1β in stimulating proapoptotic and proinflammatory cellular responses. Pharmacologic inhibition of caspases or TLR‐4 signaling reduced palmitate and IL‐1β induced cartilage damage.ConclusionPalmitate acts as a proinflammatory and catabolic factor that, in synergy with IL‐1β, induces chondrocyte apoptosis and articular cartilage breakdown. Collectively, our data suggest that elevated levels of saturated FFAs that are often found in patients who are obese may contribute to the pathogenesis of OA.
The Risk of Systemic Lupus Erythematosus Associated With Vaccines: An International Case‐Control Study
Authors: Grimaldi‐Bensouda Lamiae , Le Guern Veronique , Kone‐Paut Isabelle , Aubrun Elodie , Fain Olivier , Ruel Michel , Machet Laurent , Viallard Jean‐François , Magy‐Bertrand Nadine , Daugas Eric , Rossignol Michel , Abenhaim Lucien , Costedoat‐Chalumeau Nathalie ,   for the PGRx Lupus Study Group
Published: March 2014

ObjectiveStudies have suggested that systemic lupus erythematosus (SLE) may be triggered by vaccinations. We undertook this study to investigate the relationship between vaccination and onset of SLE.MethodsThis international case–control study was conducted between April 2008 and June 2012 in 36 specialist referral centers (34 in France and 2 in Quebec, Canada) and recruited patients ≤60 years old recently diagnosed as having either definite SLE (meeting ≥4 American College of Rheumatology [ACR] criteria including at least 1 immunologic criterion) or probable SLE (meeting 3 ACR criteria including at least 1 immunologic criterion). Controls were recruited from general practice settings through a closely monitored protocol and matched to patients by age, sex, region of residence, and date of recruitment. Vaccinations and other potential risk factors for SLE were assessed using a standardized telephone interview. We compared proportions of patients and controls who were vaccinated 12 and 24 months before the index date (date of first clinical symptom presented by the patient) using odds ratios (ORs) from conditional logistic regression.ResultsWe assessed 105 patients (89 with definite SLE and 16 with probable SLE) and 712 controls. Twenty‐two of the 105 patients (21.0%) and 181 of the 712 controls (25.4%) had received at least 1 vaccination within 24 months before the index date (adjusted OR 0.9 [95% confidence interval 0.5–1.5]). The proportions of patients and controls vaccinated within the previous 12 months were also similar.ConclusionOur study showed no association between exposure to vaccination and risk of developing SLE.
Organocatalytic Asymmetric Friedel–Crafts Reaction of Sesamol with Isatins: Access to Biologically Relevant 3‐Aryl‐3‐hydroxy‐2‐oxindoles
Authors: Kumar Akshay , Kaur Jasneet , Chauhan Pankaj , Singh Chimni Swapandeep 
Published: March 2014

AbstractThe Friedel–Crafts reaction of electron‐rich phenols with isatins was developed by employing bifunctional thiourea–tertiary amine organocatalysts. Cinchona alkaloid derived thiourea epiCDT‐3 a efficiently catalyzed the Friedel–Crafts‐type addition of phenols to isatin derivatives to provide 3‐aryl‐3‐hydroxy‐2‐oxindoles 7 and 9 in good yield (80–95 %) with good enantiomeric excess (83–94 %). Friedel–Crafts adduct 7 t was subjected to a copper(I)‐catalyzed azide–alkyne cycloaddition to obtain biologically important 3‐aryl‐3‐hydroxy‐2‐oxindole 11 in good enantiomeric excess and having a 1,2,3‐triazole moiety.
Diels–Alder/Oxidative Aromatization Approach towards the All‐Carbon DEF Tricyclic Skeleton of Daphenylline
Authors: Li Huilin , Qiu Yangcheng , Zhao Changgui , Yuan Ziyun , Xie Xingang , She Xuegong 
Published: March 2014

AbstractDaphenylline is a recently isolated Daphniphyllum alkaloid with an unprecedented novel hexacyclic scaffold. In this study, the synthesis of the fused all‐carbon DEF tricyclic skeleton of daphenylline has been accomplished. Key steps of the reported sequence involve Evans asymmetric allylation, aldol condensation, Diels–Alder reaction, and oxidative aromatization reactions. The developed strategy might lead to the total synthesis of daphenylline.
o‐Carborane‐based Biphenyl and p‐Terphenyl Derivatives
Authors: Morisaki Yasuhiro , Tominaga Masato , Ochiai Takuya , Chujo Yoshiki 
Published: March 2014

AbstractThe synthesis and properties of biphenyl‐ and p‐terphenyl‐fused o‐carboranes are described. Aryl rings in the biphenyl and p‐terphenyl skeletons are highly coplanar because of the presence of the o‐carborane unit. o‐Carborane exhibits an electron‐withdrawing character via the inductive effect, resulting in a decrease in both the HOMO and LUMO levels of oligophenyls without causing electronic perturbation.
Chemiluminometric determination of ascorbic acid in pharmaceutical formulations exploiting photo‐activation of GSH‐capped CdTe quantum dots
Authors: Sasaki M. K. , Ribeiro D. S. M. , Frigerio C. , Prior J. A. V. , Santos J. L. M. , Zagatto E. A. G. 
Published: March 2014

ABSTRACTAn automated multi‐pumping flow system is proposed for the chemiluminometric determination of ascorbic acid in pharmaceutical formulations, relying on the ability of semiconductor nanocrystals to generate short‐lived reactive species upon photo‐irradiation. A photo‐unit based on visible‐light‐emitting diodes is used to photo‐excite cadmium telluride (CdTe) quantum dots capped with glutathione, leading to the generation of radicals that react with luminol under alkaline conditions, yielding the chemiluminescence. Ascorbic acid acts as a radical scavenger, preventing the oxidation of luminol, thus ensuring a concentration‐dependent chemiluminescence quenching. After system optimization, a linear working range of 5.0 × 10‐7 to 5.0 × 10‐6 mol/L ascorbic acid (r = 0.9967, n = 5) was attained, with a detection limit of 3.05 × 10‐7 mol/L and a sampling rate of 200/h. The flow system was applied to the analysis of pharmaceutical formulations and the results were in good agreement with those obtained by the reference titrimetric procedure (RD &#60; ± 4.3%, n = 7). Copyright © 2014 John Wiley & Sons, Ltd.