bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactivity of Oxygen Radical Anions Bound to Scandia Nanoparticles in the Gas Phase: CH Bond Activation
Authors: Tian Li‐Hua , Meng Jing‐Heng , Wu Xiao‐Nan , Zhao Yan‐Xia , Ding Xun‐Lei , He Sheng‐Gui , Ma Tong‐Mei 
Published: December 2013

AbstractThe activation of CH bonds in alkanes is currently a hot research topic in chemistry. The atomic oxygen radical anion (O−.) is an important species in CH activation. The mechanistic details of CH activation by O−. radicals can be well understood by studying the reactions between O−. containing transition metal oxide clusters and alkanes. Here the reactivity of scandium oxide cluster anions toward n‐butane was studied by using a high‐resolution time‐of‐flight mass spectrometer coupled with a fast flow reactor. Hydrogen atom abstraction (HAA) from n‐butane by (Sc2O3)NO− (N=1–18) clusters was observed. The reactivity of (Sc2O3)NO− (N=1–18) clusters is significantly sizedependent and the highest reactivity was observed for N=4 (Sc8O13−) and 12 (Sc24O37−). Larger (Sc2O3)NO− clusters generally have higher reactivity than the smaller ones. Density functional theory calculations were performed to interpret the reactivity of (Sc2O3)NO− (N=1–5) clusters, which were found to contain the O−. radicals as the active sites. The local charge environment around the O−. radicals was demonstrated to control the experimentally observed size‐dependent reactivity. This work is among the first to report HAA reactivity of cluster anions with dimensions up to nanosize toward alkane molecules. The anionic O−. containing scandium oxide clusters are found to be more reactive than the corresponding cationic ones in the CH bond activation.
Ethane‐Bridged Periodic Mesoporous Organosilicas Functionalized with High Loadings of Carboxylic Acid Groups: Synthesis, Bifunctionalization, and Fabrication of Metal Nanoparticles
Authors: Deka Juti Rani , Kao Hsien‐Ming , Huang Shu‐Ying , Chang Wei‐Chieh , Ting Chun‐Chiang , Rath Purna Chandra , Chen Ching‐Shiun 
Published: December 2013

AbstractWell‐ordered periodic mesoporous organosilicas (PMOs) functionalized with high contents of carboxylic acid (COOH) groups, up to 85 mol % based on silica, were synthesized by co‐condensation of 1,2‐bis(triethoxysilyl)ethane (BTEE) and carboxyethylsilanetriol sodium salt (CES) under acidic conditions by using alkyl poly(oxyethylene) surfactant Brij 76 as a structure‐directing agent. A variety of techniques including powder X‐ray diffraction (XRD), nitrogen adsorption/desorption, Fourier‐transformed infrared (FTIR), transmission electron microscopy (TEM), 13C‐ and 29Si solid‐state nuclear magnetic resonance (NMR) were used to characterize the products. The materials thus obtained were used as an effective support to synthesize metal nanoparticles (Ag and Pt) within the channel of 2D hexagonal mesostructure of PMOs. The size and distribution of the nanoparticles were observed to be highly dependent on the interaction between the carboxylic acid functionalized group and the metal precursors. The size of Pt nanoparticles reduced from 3.6 to 2.5 nm and that of Ag nanoparticles reduced from 5.3 to 3.4 nm with the increase in the COOH loading from 10 to 50 %.
Theoretical and Structural Analysis of Long CC Bonds in the Adducts of Polycyanoethylene and Anthracene Derivatives and Their Connection to the Reversibility of Diels–Alder Reactions
Authors: Hirsch Anna K. H. , Reutenauer Philippe , Le Moignan Marc , Ulrich Sébastien , Boul Peter J. , Harrowfield Jack M. , Jarowski Peter D. , Lehn Jean‐Marie 
Published: December 2013

AbstractX‐ray structure determinations on four Diels–Alder adducts derived from the reactions of cyano‐ and ester‐substituted alkenes with anthracene and 9,10‐dimethylanthracene have shown the bonds formed in the adduction to be particularly long. Their lengths range from 1.58 to 1.62 Å, some of the longest known for Diels–Alder adducts. Formation of the four adducts is detectably reversible at ambient temperature and is associated with free energies of reaction ranging from −2.5 to −40.6 kJ mol−1. The solution equilibria have been experimentally characterised by NMR spectroscopy. Density‐functional‐theory calculations at the MPW1K/6‐31+G(d,p) level with PCM solvation agree with experiment with average errors of 6 kJ mol−1 in free energies of reaction and structural agreement in adduct bond lengths of 0.013 Å. To understand more fully the cause of the reversibility and its relationship to the long adduct bond lengths, natural‐bond‐orbital (NBO) analysis was applied to quantify donor–acceptor interactions within the molecules. Both electron donation into the σ*‐anti‐bonding orbital of the adduct bond and electron withdrawal from the σ‐bonding orbital are found to be responsible for this bond elongation.
Nanosheet‐Stacked Chiral Silica Transcribed from Metal Ion‐ and pH‐Tuned Supramolecular Crystalline Complexes of Polyamine‐D‐Glucarate
Authors: Matsukizono Hiroyuki , Murada Hiroki , Jin Ren‐Hua 
Published: December 2013

AbstractD‐Glucaric acid (D‐Glc) associates with linear poly(ethyleneimine) (PEI) through hydrogen bonding and electrostatic interactions in aqueous media to form nanostructured crystalline PEI/D‐Glc/H2O complexes with PEI/D‐Glc/H2O ratios of 2:1:2. These complexes can serve as templates for silica depositions from hydrolytic condensation of tetramethoxysilane to guide morphologically duplicated silica under very mild conditions. Their microscale morphologies are tunable by use of the crystalline complexes regulated in the different pH of the PEI/D‐Glc solutions. It was also found that some metal ions added in the PEI/D‐Glc complexation process could have a synergistic effect under a certain pH regimes, bringing about remarkable changes in the hierarchy of the resulting complexes. Especially, the complexes formed through fine‐tuning of the complexation conditions could direct torsionally stacked silica nanosheets, in which the nanosheets are composed of orderly‐bundled nanofibrils. Final elimination of organic components of the templates afforded chiral inorganic silica while retaining the morphologically higher‐order structures. The chirality of the silica, which was obtained after calcination at 600 °C, was characterized by means of diffused reflectance circular dichroism (DRCD) spectroscopy with a remote confirmation of the appearance of induced‐CD (ICD) signals of achiral or racemic chromophores covalently linked on the silica frames. Interestingly, the shapes and signs of these ICD signals are dramatically changed depending on the pH‐tuned templates used in silicification and are strongly correlated to that of the CD signals of the complex templates, indicating that the chiral transcription proceeds accurately with imprinting the higher‐order chirality of the complexes on the morphologically structured silica networks.
Polar Red‐Emitting Rhodamine Dyes with Reactive Groups: Synthesis, Photophysical Properties, and Two‐Color STED Nanoscopy Applications
Authors: Kolmakov Kirill , Wurm Christian A. , Meineke Dirk N. H. , Göttfert Fabian , Boyarskiy Vadim P. , Belov Vladimir N. , Hell Stefan W. 
Published: December 2013

AbstractThe synthesis, reactivity, and photophysical properties of new rhodamines with intense red fluorescence, two polar residues (hydroxyls, primary phosphates, or sulfonic acid groups), and improved hydrolytic stability of the amino‐reactive sites (NHS esters or mixed N‐succinimidyl carbonates) are reported. All fluorophores contain an N‐alkyl‐1,2‐dihydro‐2,2,4‐trimethylquinoline fragment, and most of them bear a fully substituted tetrafluoro phenyl ring with a secondary carboxamide group. The absorption and emission maxima in water are in the range of 635–639 and 655–659 nm, respectively. A vastly simplified approach to red‐emitting rhodamines with two phosphate groups that are compatible with diverse functional linkers was developed. As an example, a phosphorylated dye with an azide residue was prepared and was used in a click reaction with a strained alkyne bearing an N‐hydroxysuccinimid (NHS) ester group. This method bypasses the undesired activation of phosphate groups, and gives an amphiphilic amino‐reactive dye, the solubility and distribution of which between aqueous and organic phases can be controlled by varying the pH. The presence of two hydroxyl groups and a phenyl ring with two carboxyl residues in the dyes with another substitution pattern is sufficient for providing the hydrophilic properties. Selective formation of a mono‐N‐hydroxysuccinimidyl ester from 5‐carboxy isomer of this rhodamine is reported. The fluorescence quantum yields varied from 58 to 92 % for free fluorophores, and amounted to 18–64 % for antibody conjugates in aqueous buffers. The brightness and photostability of these fluorophores facilitated two‐color stimulated emission depletion (STED) fluorescence nanoscopy of biological samples with high contrast and minimal background. Selecting a pair of fluorophores with absorption/emission bands at 579/609 and 635/655 nm enabled two‐color channels with low cross‐talk and negligible background at approximately 40 nm resolution.
Stereoselective Synthesis of Fluoroalkenoates and Fluorinated Isoxazolidinones: N‐Substituents Governing the Dual Reactivity of Nitrones
Authors: Prakash G. K. Surya , Zhang Zhe , Wang Fang , Rahm Martin , Ni Chuanfa , Iuliucci Marc , Haiges Ralf , Olah George A. 
Published: December 2013

Abstractα‐Fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones are of vast interest due to their potential biological applications. We now demonstrate the syntheses of (E)‐α‐fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones by the reactions between nitrones and α‐fluoro‐α‐bromoacetate. By altering N‐substituents in nitrones, (E)‐α‐fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones can be achieved, respectively, with high chemo‐ and stereoselectivities. Experimental and computational studies have been conducted to elucidate the reaction mechanisms. Linear free energy relationship studies further revealed that the N‐substituent effects are primarily of electronic origin.
Reactivity of TpMe2‐Supported Yttrium Alkyl Complexes toward Aromatic N‐Heterocycles: Ring‐Opening or CC Bond Formation Directed by CH Activation
Authors: Yi Weiyin , Zhang Jie , Huang Shujian , Weng Linhong , Zhou Xigeng 
Published: December 2013

AbstractUnusual chemical transformations such as three‐component combination and ring‐opening of N‐heterocycles or formation of a carbon–carbon double bond through multiple C–H activation were observed in the reactions of TpMe2‐supported yttrium alkyl complexes with aromatic N‐heterocycles. The scorpionate‐anchored yttrium dialkyl complex [TpMe2Y(CH2Ph)2(THF)] reacted with 1‐methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24‐membered rare‐earth metallomacrocyclic compound [TpMe2Y(μ‐N,C‐Im)(η2‐N,C‐Im)]6 (1; Im=1‐methylimidazolyl) through two kinds of C–H activations at the C2‐ and C5‐positions of the imidazole ring. However, [TpMe2Y(CH2Ph)2(THF)] reacted with two equivalents of 1‐methylbenzimidazole to afford a C–C coupling/ring‐opening/C–C coupling product [TpMe2Y{η3‐(N,N,N)‐N(CH3)C6H4NHCHC(Ph)CN(CH3)C6H4NH}] (2). Further investigations indicated that [TpMe2Y(CH2Ph)2(THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C–C coupling/ring‐opening product {(TpMe2)Y[μ‐η2:η1‐SC6H4N(CHCHPh)](THF)}2 (3). Moreover, the mixed TpMe2/Cp yttrium monoalkyl complex [(TpMe2)CpYCH2Ph(THF)] reacted with two equivalents of 1‐methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [TpMe2CpY(μ‐N,C‐Im)]3 (5), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [TpMe2Y(Im‐TpMe2)] (7; Im‐TpMe2=1‐methyl‐imidazolyl‐TpMe2) and [Cp3Y(HIm)] (8; HIm=1‐methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a CC bond through multiple C–H activations.
Copper–Boxmi Complexes as Highly Enantioselective Catalysts for Electrophilic Trifluoromethylthiolations
Authors: Deng Qing‐Hai , Rettenmeier Christoph , Wadepohl Hubert , Gade Lutz H. 
Published: December 2013

AbstractThe enantioselective trifluoromethylthiolation of β‐ketoesters using chiral copper–boxmi complexes as catalysts is reported. A number of α‐SCF3‐substituted β‐ketoesters have been obtained with up to >99 % enantiomeric excess (ee), and the trifluoromethylthiolated products were then transformed diastereoselectively to α‐SCF3‐β‐hydroxyesters with two adjacent quaternary stereocenters.
Combined Use of Warfarin and Oral P2Y12 Inhibitors in Patients With Atrial Fibrillation and Acute Coronary Syndrome
Authors: Jones W. Schuyler , Mi Xiaojuan , Patel Manesh R. , Mills Roger , Hernandez Adrian F. , Curtis Lesley H. 
Published: December 2013

AbstractBackgroundAlthough atrial fibrillation (AF) occurs frequently in patients hospitalized with acute coronary syndrome (ACS), strategies for prevention of thromboembolic complications are poorly characterized.HypothesisWe sought to examine exposure to warfarin and P2Y12 inhibitors and clinical outcomes among patients with AF and ACS.MethodsPatients age >65 years hospitalized with a primary diagnosis of ACS and a secondary diagnosis of AF between 2007 and 2010 were identified in the Medicare 5% sample. Medication exposure was ascertained during a 90‐day period following the index discharge using Medicare drug claims. Among patients who were alive and not readmitted during the ascertainment period, we examined the cumulative incidence of all‐cause mortality and all‐cause readmission by medication exposure at 1 year.ResultsA total of 2509 Medicare beneficiaries met the inclusion criteria. Among the 1633 patients (65%) who were alive and not readmitted during the 90‐day ascertainment period, 24.0% received warfarin, 38.9% received P2Y12 inhibitors, 10.2% received combination therapy, and 26.8% received neither therapy. Readmission rates were high in all groups at 1 year (warfarin, 47.5%; P2Y12 inhibitors, 46.6%; combination therapy, 38.0%; and neither therapy, 39.3%), and the overall 1‐year mortality rate was 12.5%.ConclusionsAmong Medicare beneficiaries with AF and ACS, combination therapy with warfarin and P2Y12 inhibitor was uncommon during the 90‐day ascertainment period, and more than one‐quarter of patients had no claims for warfarin or P2Y12 inhibitors. Rates of all‐cause readmission and mortality within 1 year of hospitalization for ACS were high.
The Synthesis and Biological Evaluation of Multifunctionalised Derivatives of Noscapine as Cytotoxic Agents
Authors: DeBono Aaron J. , Mistry Sarah J. , Xie Jinhan , Muthiah Divya , Phillips Jackson , Ventura Sabatino , Callaghan Richard , Pouton Colin W. , Capuano Ben , Scammells Peter J. 
Published: December 2013

AbstractNoscapine, a phthalideisoquinoline alkaloid derived from Papaver somniferum, is a well‐known antitussive drug that has a relatively safe in vitro toxicity profile. Noscapine is also known to possess weak anticancer efficacy, and since its discovery, efforts have been made to design derivatives with improved potency. Herein, the synthesis of a series of noscapine analogues, which have been modified in the 6′, 9′, 1 and 7‐positions, is described. In a previous study, replacement of the naturally occurring N‐methyl group in the 6′‐position with an N‐ethylaminocarbonyl was shown to promote cell‐cycle arrest and cytotoxicity against three cancer cell lines. Here, this modification has been combined with other structural changes that have previously been shown to improve anticancer activity, namely halo substitution in the 9′‐position, regioselective O‐demethylation to reveal a free phenol in the 7‐position, and reduction of the lactone to the corresponding cyclic ether in the 1‐position. The incorporation of new aryl substituents in the 9′‐position was also investigated. The study identified interesting new compounds able to induce G2/M cell‐cycle arrest and that possess cytotoxic activity against the human prostate carcinoma cell line PC3, the human breast adenocarcinoma cell line MCF‐7, and the human pancreatic epithelioid carcinoma cell line PANC‐1. In particular, the ethyl urea cyclic ether noscapinoids and a compound containing a 6′‐ethylaminocarbonyl along with 9′‐chloro, 7‐hydroxy and lactone moieties exhibited the most promising biological activities, with EC50 values in the low micromolar range against all three cancer cell lines, and these derivatives warrant further investigation.
Racial variation in the quality of surgical care for bladder cancer
Authors: Barocas Daniel A. , Alvarez JoAnn , Koyama Tatsuki , Anderson Christopher B. , Gray Darryl T. , Fowke Jay H. , You Chaochen , Chang Sam S. , Cookson Michael S. , Smith Joseph A. , Penson David F. 
Published: December 2013

BACKGROUNDDifferences in quality of care may contribute to racial variation in outcomes of bladder cancer (BCa). Quality indicators in patients undergoing surgery for BCa include the use of high‐volume surgeons and high‐volume hospitals, and, when clinically indicated, receipt of pelvic lymphadenectomy, receipt of continent urinary diversion, and undergoing radical cystectomy instead of partial cystectomy. The authors compared these quality indicators as well as adverse perioperative outcomes in black patients and white patients with BCa.METHODSThe Healthcare Cost and Utilization Project State Inpatient Databases for New York, Florida, and Maryland (1996‐2009) were used, because they consistently included race, surgeon, and hospital identifiers. Quality indicators were compared across racial groups using regression models adjusting for age, sex, Elixhauser comorbidity sum, insurance, state, and year of surgery, accounting for clustering within hospital.RESULTSBlack patients were treated more often by lower volume surgeons and hospitals, they had significantly lower receipt of pelvic lymphadenectomy and continent diversion, and they experienced higher rates of adverse outcomes compared with white patients. These associations remained significant for black patients who received treatment from surgeons and at hospitals in the top volume decile.CONCLUSIONSBlack patients with BCa had lower use of experienced providers and institutions for BCa surgery. In addition, the quality of care for black patients was lower than that for whites even if they received treatment in a high‐volume setting. This gap in quality of care requires further investigation. Cancer 2014;120:1018–1025. © 2013 American Cancer Society.
Malignancy risk associated with diagnostic categories defined by the Papanicolaou Society of Cytopathology pancreaticobiliary guidelines
Authors: Layfield Lester J. , Dodd Leslie , Factor Rachel , Schmidt Robert L. 
Published: December 2013

BACKGROUNDEndoscopic ultrasound‐guided fine‐needle aspiration (EUS‐FNA) is currently the predominant method for obtaining a preoperative tissue diagnosis for pancreatic lesions suspicious for malignancy. The diagnostic sensitivity and specificity of EUS‐FNA are well documented, but malignancy risk associated with the diagnostic categories proposed by the Papanicolaou Society of Cytopathology is poorly defined.METHODSThe records of the Departments of Pathology at Duke University and the University of Utah were searched for all cases of EUS‐FNA performed for the investigation of pancreatic lesions. All cases with follow‐up surgical diagnosis or greater than 3 years of clinical follow‐up were selected. Cytologic diagnostic categories were “nondiagnostic,” “benign,” “atypical (not otherwise specified),” “suspicious for malignancy,” “neoplasm,” and “malignant.” Correlation of cytologic diagnosis with surgical and/or clinical follow‐up was made and risk of malignancy calculated for each category.RESULTSThree hundred seventeen EUS‐FNAs with adequate surgical or clinical follow‐up were obtained. Risk of malignancy for nondiagnostic specimens was 21%;, benign specimens, 13%; atypical cases, 74%; suspicious for malignancy, 82%; the neoplasm category, 14%; and the malignant category, 97%CONCLUSIONSThe cytologic categories proposed by the Papanicolaou Society of Cytopathology demonstrate an increasing risk for malignancy extending from benign to malignant. Aspirates designated benign have the lowest risk of malignancy (13%) and aspirates designated malignant the highest (97%). The proposed categorization scheme stratifies risk for malignancy giving useful information to clinicians treating patients with pancreatic lesions. Cancer (Cancer Cytopathol) 2014;122:420–427. © 2013 American Cancer Society.
Water‐Soluble Ionic Palladium Complexes: Effect of Pendant Ionic Groups on Palladium Nanoparticles and Suzuki–Miyaura Reaction in Neat Water
Authors: Li Liuyi , Wu Tao , Wang Jinyun , Wang Ruihu 
Published: December 2013

AbstractThree ionic nitrogen‐containing chelating ligands (L1–L3) are synthesized readily through alkylation and quaternization of 2,2′‐dipyridylamine. The charge distributions and natural bond orbital analyses of their cations are implemented by using density functional theory calculations. The catalytic performances of their water‐soluble palladium complexes are evaluated preliminarily by using the Suzuki–Miyaura cross‐coupling reaction, and high catalytic activities of aryl bromides and chlorides are achieved in neat water. The mercury drop test, poison experiments, and TEM analysis are used to demonstrate the formation of palladium nanoparticles (NPs) after the catalytic reaction. The effects of pendant ionic groups in L1–L3 on the catalytic activities and structures of the palladium NPs are disclosed. These NPs are stable in water for several weeks; they are stabilized by synergetic interactions between the chelating coordination of the 2,2′‐dipyridylamino group to the surface of the palladium NPs and the electrostatic repulsion of the ionic groups in L1–L3.
Ferric chloride‐Graphite Intercalation Compounds as Anode Materials for Li‐ion Batteries
Authors: Wang Lili , Zhu Yongchun , Guo Cong , Zhu Xiaobo , Liang Jianwen , Qian Yitai 
Published: December 2013

AbstractFerric chloride‐graphite intercalation compounds (FeCl3–GICs) with stage 1 and stage 2 structures were synthesized by reacting FeCl3 and expanded graphite (EG) in air in a stainless‐steel autoclave. As rechargeable Li‐ion batteries, these FeCl3–GICs exhibit high capacity, excellent cycling stability, and superior rate capability, which could be attributed to their unique intercalation features. This work may enable new possibilities for the fabrication of Li‐ion batteries.