bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Formation and Self‐Assembly of Long Prebiotic Oligomers Produced by the Condensation of Unactivated Amino Acids on Oxide Surfaces
Authors: Martra Gianmario , Deiana Chiara , Sakhno Yuriy , Barberis Ilvis , Fabbiani Marco , Pazzi Marco , Vincenti Marco 
Published: February 2014

AbstractIn situ IR and mass spectrometry evidence for the catalytic formation on SiO2 and TiO2 surfaces of glycine oligomers (poly‐Gly) up to 16 units long by successive feeding with monomers from the vapor phase is presented. Parallel experiments carried out on hydroxyapatite resulted in the unreactive adsorption of Gly, thus indicating that the oligomerization was specifically catalyzed by the surfaces of SiO2 and TiO2. Furthermore, the poly‐Gly moved on the surface when contacted with H2O vapor and formed self‐assembled aggregates containing both helical and β‐sheet‐like structural motifs. These results indicate that polypeptides formed by the condensation of amino acids adsorbed on a mineral surface can evolve into structured supramolecular assemblies.
Defect‐Controlled Electronic Properties in AZn2Sb2 Zintl Phases
Authors: Pomrehn Gregory S. , Zevalkink Alex , Zeier Wolfgang G. , van de Walle Axel , Snyder G. Jeffrey 
Published: February 2014

AbstractExperimentally, AZn2Sb2 samples (A=Ca, Sr, Eu, Yb) are found to have large charge carrier concentrations that increase with increasing electronegativity of A. Using density functional theory (DFT) calculations, we show that this trend can be explained by stable cation vacancies and the corresponding finite phase width in A1−xZn2Sb2 compounds.
Antibody–Drug Conjugates: An Emerging Concept in Cancer Therapy
Authors: Chari Ravi V. J. , Miller Michael L. , Widdison Wayne C. 
Published: February 2014

AbstractTraditional cancer chemotherapy is often accompanied by systemic toxicity to the patient. Monoclonal antibodies against antigens on cancer cells offer an alternative tumor‐selective treatment approach. However, most monoclonal antibodies are not sufficiently potent to be therapeutically active on their own. Antibody–drug conjugates (ADCs) use antibodies to deliver a potent cytotoxic compound selectively to tumor cells, thus improving the therapeutic index of chemotherapeutic agents. The recent approval of two ADCs, brentuximab vedotin and ado‐trastuzumab emtansine, for cancer treatment has spurred tremendous research interest in this field. This Review touches upon the early efforts in the field, and describes how the lessons learned from the first‐generation ADCs have led to improvements in every aspect of this technology, i.e., the antibody, the cytotoxic compound, and the linker connecting them, leading to the current successes. The design of ADCs currently in clinical development, and results from mechanistic studies and preclinical and clinical evaluation are discussed. Emerging technologies that seek to further advance this exciting area of research are also discussed.
Heteroatom‐Free Arene‐Cobalt and Arene‐Iron Catalysts for Hydrogenations
Authors: Gärtner Dominik , Welther Alice , Rad Babak Rezaei , Wolf Robert , Jacobi von Wangelin Axel 
Published: February 2014

Abstract75 years after the discovery of hydroformylation, cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. We have evaluated arene metalates in which the low‐valent metal species is—conceptually different from heteroatom‐based ligands—stabilized by π coordination to hydrocarbons. Potassium bis(anthracene)cobaltate 1 and ‐ferrate 2 can be viewed as synthetic precursors of quasi‐“naked” anionic metal species; their aggregation is effectively impeded by (labile) coordination to the various π acceptors present in the hydrogenation reactions of unsaturated molecules (alkenes, arenes, carbonyl compounds). Kinetic studies, NMR spectroscopy, and poisoning studies of alkene hydrogenations support the formation of a homogeneous catalyst derived from 1 which is stabilized by the coordination of alkenes. This catalyst concept complements the use of complexes with heteroatom donor ligands for reductive processes.
Enantioselective Synthesis of Boron‐Substituted Quaternary Carbon Stereogenic Centers through NHC‐Catalyzed Conjugate Additions of (Pinacolato)boron Units to Enones
Authors: Radomkit Suttipol , Hoveyda Amir H. 
Published: February 2014

AbstractThe first examples of Lewis base catalyzed enantioselective boryl conjugate additions (BCAs) that generate products containing boron‐substituted quaternary carbon stereogenic centers are disclosed. Reactions are performed in the presence of 1.0–5.0 mol % of a readily accessible chiral accessible N‐heterocyclic carbene (NHC) and commercially available bis(pinacolato)diboron; cyclic or linear α,β‐unsaturated ketones can be used and rigorous exclusion of air or moisture is not necessary. The desired products are obtained in 63–95 % yield and 91:9 to >99:1 enantiomeric ratio (e.r.). The special utility of the NHC‐catalyzed approach is demonstrated in the context of an enantioselective synthesis of natural product antifungal (−)‐crassinervic acid.
A Quantitative Relaxometric Version of the ELISA Test for the Measurement of Cell Surface Biomarkers
Authors: Alberti Diego , van't Erve Mark , Stefania Rachele , Ruggiero Maria Rosaria , Tapparo Marta , Geninatti Crich Simonetta , Aime Silvio 
Published: February 2014

AbstractQuantitative measurement of marker expression in diseased cells is still a topic of considerable interest and different methodologies are currently under intense scrutiny. This work aims at developing an in vitro diagnostic method based on the release of paramagnetic species from relaxometrically “silent” liposomes operated by the action of a phospholipase A2 (PLA2) previously targeted to the epitope of interest. The released paramagnetic species causes an increase of the longitudinal water proton relaxation rate proportional to the number of PLA2 bound to the cell outer surface. The sensitivity of the herein proposed method, named R‐ELISA, was attempted in the detection of folate receptor expression on human ovarian cancer cells by functionalizing PLA2 with folic acid. Receptor/cell number of 8.3×105 has been measured on IGROV‐1 cells. The R‐ELISA assay can detect nanomolar cell suspension receptor concentrations and has been validated by well‐established spectrofluorimetric procedures.
Pressure‐Induced Intersite BiM (M=Ru, Ir) Valence Transitions in Hexagonal Perovskites
Authors: Huang Zixin , Auckett Josie E. , Blanchard Peter E. R. , Kennedy Brendan J. , Miiller Wojciech , Zhou Qingdi , Avdeev Maxim , Johnson Mark R. , Zbiri Mohamed , Garbarino Gaston , Marshall William G. , Gu Qinfen , Ling Chris D. 
Published: February 2014

AbstractPressure‐induced charge transfer from Bi to Ir/Ru is observed in the hexagonal perovskites Ba3+nBiM2+nO9+3n (n=0,1; M=Ir,Ru). These compounds show first‐order, circa 1 % volume contractions at room temperature above 5 GPa, which are due to the large reduction in the effective ionic radius of Bi when the 6s shell is emptied on oxidation, compared to the relatively negligible effect of reduction on the radii of Ir or Ru. They are the first such transitions involving 4d and 5d compounds, and they double the total number of cases known. Ab initio calculations suggest that magnetic interactions through very short (ca. 2.6 Å) MM bonds contribute to the finely balanced nature of their electronic states.
Diamond: Electronic Ground State of Carbon at Temperatures Approaching 0 K
Authors: Grochala Wojciech 
Published: February 2014

AbstractThe relative stability of graphite and diamond is revisited with hybrid density functional theory calculations. The electronic energy of diamond is computed to be more negative by 1.1 kJ mol−1 than that of graphite at T=0 K and in the absence of external pressure. Graphite gains thermodynamic stability over diamond at 298 K only because of the differences in the zero‐point energy, specific heat, and entropy terms for both polymorphs.
Comparison of preparation methods for iron–alumina oxygen carrier and its reduction kinetics with hydrogen in chemical looping combustion
Authors: Zhao Haibo , Mei Daofeng , Ma Jinchen , Zheng Chuguang 
Published: February 2014

ABSTRACTSeven preparation methods, namely sol‐gel, co‐precipitation, hydrothermal synthesis, low heating solid‐state reaction, freeze granulation, combustion synthesis, and mechanical mixing, were used to synthesize Fe2O3/Al2O3 oxygen carrier for chemical looping combustion. A comprehensive physicochemical characterization (i.e. productivity, crushing strength, crystalline characteristics, microstructure, and chemical reactivity with hydrogen) was carried out, and the effects of preparation methods and processes on the oxygen carrier performance were explored. Taking into consideration various physicochemical indices, the sol‐gel method and the freeze granulation method were preferred for oxygen carrier preparation. Following that, a critical chemical reaction in in situ gasification chemical looping combustion, the reduction reaction between oxygen carrier and hydrogen, was clarified in terms of reaction kinetics through the non‐isothermal kinetics analysis and the double extrapolation method. Temperature programmed reduction experiments of the sol‐gel‐derived Fe2O3/Al2O3 particle and hydrogen were performed using a chemisorption analyzer. The reduction mechanisms and kinetics parameters for the two‐stage reaction (reduced from Fe2O3 to Fe3O4 and then from Fe3O4 to FeAl2O4) were determined. In the first stage, the reduction reaction is described by the surface reaction model with an order of 2; on the other hand, the conversion from Fe3O4 to FeAl2O4 is dominated by the nucleation and nuclei growth process. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Acrylonitrile–butadiene–styrene/poly(vinyl acetate)/nanosilica mixed matrix membrane for He/CH4 separation
Authors: Bandehali Samaneh , Kargari Ali , Moghadassi Abdolreza , Saneepur Hamidreza , Ghanbari Davood 
Published: February 2014

ABSTRACTIn the present work, the separation of He/CH4 through different polymeric membranes has been considered. In this regard, composite flat sheet membranes are prepared from blending acrylonitrile–butadiene–styrene (ABS) with different amounts of poly(vinyl acetate) (PVAc) (0–40 wt%). Gas permeability/selectivity analyses as well as the pressure effects were studied for the prepared membranes. The results demonstrated that the ABS/PVAc (20 wt%) membrane revealed higher permselectivity. Afterwards, novel mixed matrix membranes were prepared by incorporating 1–5 wt% SiO2 nanoparticles into the ABS/PVAc (20 wt%). Additionally, further modification was carried out with the addition of styrene–butadiene–rubber (SBR) (5–15 wt%). The primary results of the prepared mixed matrix membranes showed a significant increase in the He permeability together with a decrease in He/CH4 selectivity by incorporating the SiO2 nanoparticles into the blend membranes. Finally, with the introduction of SBR, the (He permeability) selectivity was enhanced from (6.30 Barrer) 45 for the neat ABS/PVAc (20 wt%) to (42.39 Barrer) 51.88 for the ABS/PVAc (20 wt%)/SiO2 (3 wt%)/SBR (15 wt%) membrane. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis and characterization of fluorene‐based polybenzimidazole copolymer for gas separation
Authors: Han Jun Young , Lee Ju Yeon , Kim Hyoung‐Juhn , Kim Man‐Ho , Han Su Gyeong , Jang Jong Hyun , Cho Eun Ae , Yoo Sung Jong , Henkensmeier Dirk 
Published: February 2014

ABSTRACTThe purpose of this study is to develop new cardo‐polybenzimidazole (CPBI) copolymers containing cardo fluorene, with improved gas permeability, specifically oxygen permeability. The characteristics of these copolymers are investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance, 1H and 13C), thermo‐gravimetric analysis, and wide‐angle X‐ray diffraction. These membranes fabricated from copolymers have relatively high oxygen diffusion coefficients, determined using gas permeation. In particular, the CPBI‐co91 (synthesized by using the monomers ratio containing dibenzoic acid = 9 : 1) membrane have oxygen permeability coefficient (PO2) of 10.69 Barrer, theoretical selectivity of 5.4 for oxygen to nitrogen, and O2 diffusion coefficient of 9.64 × 10−8 cm2/s. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40521.
Synthesis of end‐functionalized poly(N‐isopropyl acrylamide) with zinc porphyrin and its photocatalytic activity under visible light
Authors: Qiu Nannan , Li Yanhui , Han Shuangli , Satoh Toshifumi , Kakuchi Toyoji , Duan Qian 
Published: February 2014

ABSTRACTA series of well‐defined linear poly(N‐isopropyl acrylamide) with an asymmetrical zinc(II) porphyrin (ZnPor–PAM) end group was synthesized by atom transfer radical polymerization, wherein 5,10,15,20‐tetra(p‐bromopropanoyloxyethylphenyl) zinc porphyrin tripropionate was used as the initiator and CuBr/tris(2‐dimeoethyl)amine was used as the catalyst system. The structure of the ZnPor–PAM was characterized by Fourier transform infrared spectroscopy and 1H‐NMR. In addition, the polydispersity index (PDI) obtained by gel permeation chromatography indicated that the molecular weight distribution was narrow; thus, the polymerization was well controlled (1.05 < PDI < 1.21). Because of the incorporation of hydrophobic porphyrin, the lower critical solution temperature of ZnPor–PAM was lower than that of the N‐isopropyl acrylamide homopolymer. Most interestingly, the ZnPor–PAM possessed remarkable photocatalytic activity for the oxidative degradation of methylene blue in the presence of hydrogen peroxide under visible‐light radiation. Moreover, ZnPor–PAM could be reused through the uncomplicated procedure, which exploited the thermoresponsive properties of ZnPor–PAM without any significant loss in activity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40523.
Cr3+:SrGa12O19: A Broadband Near‐Infrared Long‐Persistent Phosphor
Authors: Xu Ju , Chen Daqin , Yu Yunlong , Zhu Wenjuan , Zhou Jiangchong , Wang Yuansheng 
Published: February 2014

AbstractCr3+‐doped SrGa12O19 is demonstrated to be a broadband near‐infrared (650–950 nm) long‐persistent phosphor whose luminescence can last for more than 2 h after ultraviolet irradiation is stopped. Detailed analysis of the photoluminescence and thermoluminescence spectra and of the persistent decay behavior of the Cr3+‐doped SrGa12O19 samples indicate that the persistent energy transfer from the SrGa12O19 host to the Cr3+ ions and the filling and release of electrons into and from the shallow and deep traps through the conduction band is responsible for the long‐persistent phosphorescence.
Consequences of Block Sequence on the Orthogonal Folding of Triblock Copolymers
Authors: Hosono Nobuhiko , Stals Patrick J. M. , Palmans Anja R. A. , Meijer E. W. 
Published: February 2014

AbstractABA‐ and BAB‐type triblock copolymers possessing pendant, self‐assembling motifs in the A and B blocks were synthesized, with 2‐ureidopyrimidinone (UPy) and benzene‐1,3,5‐tricarboxamide (BTA) for the A and B block, respectively. They were investigated to assess if and how the polymer’s microstructure influences the self‐assembly behavior of the supramolecular motifs and, as a result, the single‐chain folding process. BAB‐type triblock copolymers were synthesized via atom transfer radical polymerization (ATRP) with molecular weights ranging from 30 to 120 kg mol−1; the BTA and UPy motifs were attached using a post‐functionalization approach. The ABA‐type triblock copolymers were available from previous work. In highly dilute solutions, both types of triblock copolymers fold into single‐chain polymeric nanoparticles (SCPNs) via thermally induced BTA self‐assembly and photo‐triggered UPy dimerization. Chain collapse induced by intramolecular UPy dimerization was evaluated using size‐exclusion chromatography (SEC). The BTA self‐assembly was monitored by circular dichroism (CD) spectroscopy. The microstructures of SCPNs were visualized by atomic force microscopy (AFM). SEC analysis indicated a more loose packing for the BAB‐type folded nanoparticles than for the ABA‐type ones, which implies that topological differences in the polymer architecture do affect the folding behavior, although only slightly. The facile synthetic protocol developed here provides topologically different triblock architectures and opens up the area for single‐chain folding technology that is applicable in artificial enzymatic systems with compartmentalized domains.
Inhibitory effect of ciprofloxacin on β‐glucuronidase‐mediated deconjugation of mycophenolic acid glucuronide
Authors: Kodawara Takaaki , Masuda Satohiro , Yano Yoshitaka , Matsubara Kazuo , Nakamura Toshiaki , Masada Mikio 
Published: February 2014

ABSTRACTThe interaction between mycophenolate (MPA) and quinolone antibiotics such as ciprofloxacin is considered to reduce the enterohepatic recycling of MPA, which is biotransformed in the intestine from MPA glucuronide (MPAG) conjugate excreted via the biliary system; however, the molecular mechanism underlying this biotransformation of MPA is still unclear. In this study, an in vitro system was established to evaluate β‐glucuronidase‐mediated deconjugation and to examine the influence of ciprofloxacin on the enzymatic deconjugation of MPAG and MPA resynthesis. Resynthesis of MPA via deconjugation of MPAG increased in a time‐dependent manner from 5 to 60 min in the presence of β‐glucuronidase. Ciprofloxacin and phenolphthalein‐β‐d‐glucuronide (PhePG), a typical β‐glucuronidase substrate, significantly decreased the production of MPA from MPAG in the β‐glucuronidase‐mediated deconjugation system. In addition, enoxacin significantly inhibited the production of MPA from MPAG, while levofloxacin and ofloxacin had no inhibitory effect on MPA synthesis. Pharmacokinetic analysis revealed that ciprofloxacin showed a dose‐dependent inhibitory effect on MPA production from MPAG via β‐glucuronidase with a half‐maximal inhibitory concentration (IC50) value of 30.4 µm. While PhePG inhibited the β‐glucuronidase‐mediated production of MPA from MPAG in a competitive manner, ciprofloxacin inhibited MPA synthesis via noncompetitive inhibition. These findings suggest that the reduction in the serum MPA concentration during the co‐administration of ciprofloxacin is at least in part due to the decreased enterohepatic circulation of MPA because of noncompetitive inhibition of deconjugation of MPAG by intestinal β‐glucuronidase. Copyright © 2014 John Wiley & Sons, Ltd.
Chemiluminescence accompanied by the reaction of acridinium ester and manganese (II)
Authors: Ren Lingling , Cui Hua 
Published: February 2014

ABSTRACTAn acridinium ester (AE) alkaline solution can react with Mn(II) to generate a strong chemiluminescence (CL) centered at 435 nm. The effects of reaction conditions such as pH and Mn(II) concentration on CL intensity were examined. In order to explore the CL mechanism, the effect of oxygen on the CL reaction was examined and an X‐ray photoelectron spectroscopy study of the reaction precipitate was carried out. The results indicated that oxygen participated in the CL reaction and Mn(IV) was the primary product in the system. A possible mechanism was proposed that involved two pathways: (1) dissolved oxygen was reduced to reactive oxygen radicals by Mn(II), these reactive intermediates then reacted with AE to produce excited state acridone; (2) Mn(II) could reduce AE to partly reduced AE, which then reacted with oxygen to form excited state acridone. The reactions of other metal ions with AE were also tested, and only Mn(II) was shown to trigger strong CL emission of AE, which indicated that the system had good selectivity for Mn(II). Copyright © 2014 John Wiley & Sons, Ltd.
Surgical resection strategy and the influence of radicality on outcomes in oesophageal cancer
Authors: Davies A R , Sandhu H , Pillai A , Sinha P , Mattsson F , Forshaw M J , Gossage J A , Lagergren J , Allum W H , Mason R C 
Published: February 2014

Abstract

Background
The optimal surgical approach to tumours of the oesophagus and oesophagogastric junction remains controversial. The principal randomized trial comparing transhiatal (THO) and transthoracic (TTO) oesophagectomy showed no survival difference, but suggested that some subgroups of patients may benefit from the more extended lymphadenectomy typically conducted with TTO.

Methods
This was a cohort study based on two prospectively created databases. Short- and long-term outcomes for patients undergoing THO and TTO were compared. The primary outcome measure was overall survival, with secondary outcomes including time to recurrence and patterns of disease relapse. A Cox proportional hazards model provided hazard ratios (HRs) and 95 per cent confidence intervals (c.i.), with adjustments for age, tumour stage, tumour grade, response to chemotherapy and lymphovascular invasion.

Results
Of 664 included patients (263 THO, 401 TTO), the distributions of age, sex and histological subtype were similar between the groups. In-hospital mortality (1·1 versus 3·2 per cent for THO and TTO respectively; P = 0·110) and in-hospital stay (14 versus 17 days respectively; P &lt; 0·001) favoured THO. In the adjusted model, there was no difference in overall survival (HR 1·07, 95 per cent c.i. 0·84 to 1·36) or time to tumour recurrence (HR 0·99, 0·76 to 1·29) between the two operations. Local tumour recurrence patterns were similar (22·8 versus 24·4 per cent for THO and TTO respectively). No subgroup could be identified of patients who had benefited from more radical surgery on the basis of tumour location or stage.

Conclusion
There was no difference in survival or tumour recurrence for TTO and THO.
The Efficacies of Cell‐Penetrating Peptides in Accumulating in Large Unilamellar Vesicles Depend on their Ability To Form Inverted Micelles
Authors: Swiecicki Jean‐Marie , Bartsch Annika , Tailhades Julien , Di Pisa Margherita , Heller Benjamin , Chassaing Gérard , Mansuy Christelle , Burlina Fabienne , Lavielle Solange 
Published: February 2014

AbstractIn this study, the direct translocation of cell‐penetrating peptides (CPPs) into large unilamellar vesicles (LUVs) was shown to be rapid for all the most commonly used CPPs. This translocation led within a few minutes to intravesicular accumulation up to 0.5 mM, with no need for a transbilayer potential. The accumulation of CPPs inside LUVs was found to depend on CPP sequence, CPP extravesicular concentration and phospholipid (PL) composition, either in binary or ternary mixtures of PLs. More interestingly, the role of anionic phospholipid flip‐flopping in the translocation process was ascertained. CPPs enhanced the flipping of PLs, and the intravesicular CPP accumulation directly correlated with the amount of anionic PLs that had been transferred from the external to the internal leaflet of the LUV bilayer, thus demonstrating the transport of peptide/lipid complexes as inverted micelles.
Long‐term survival after two surgical resections of peritoneal metastases from hepatocellular carcinoma with an interval of 4 years
Authors: Kitajima Toshihiro , Hashimoto Masaji , Sasaki Kazunari , Matsuda Masamichi , Kuroda Yoko , Fujii Takeshi , Watanabe Goro 
Published: February 2014

Key Clinical MessageWe propose that surgical resections of peritoneal metastases arising from hepatocellular carcinoma are an option for selected patients with controlled HCC in the liver, and without metastases in other organs, when the complete removal of such metastases can be achieved, especially in the case of patients with normal liver function.