bluuebunny/crossref_metadata_2025_split huggingface dataset:
Total Syntheses of Periconiasins A–E
Authors: Tian Chong , Lei Xiaoqiang , Wang Yuanhao , Dong Zhen , Liu Gang , Tang Yefeng 
Published: April 2016

AbstractThe first and collective total syntheses of periconiasins A–E, a group of naturally occurring cytochalasans, were achieved by a series of rationally designed or bioinspired transformations. Salient features of the syntheses include a tandem aldol condensation/Grob fragmentation to assemble the linear polyketide–amino acid hybrid precursor, a Diels–Alder macrocylization to construct the 9/6/5 tricyclic core of periconiasins A–C, and a transannular carbonyl–ene reaction to forge the polycyclic framework of periconiasins D and E.
High‐performance PDMS membranes for pervaporative removal of VOCs from water: The role of alkyl grafting
Authors: Zhou Hui , Su Yi , Chen Xiangrong , Luo Jianquan , Wan Yinhua 
Published: April 2016

ABSTRACTTo improve the pervaporation performance of PDMS membrane, alkyl groups with different chain length were grafted into PDMS matrix. The prepared membranes were characterized by ATR‐IR, DSC, TGA, PALS, and tensile testing. The effects of alkyl grafting on pervaporation performance of PDMS membrane were investigated in separation of ethyl acetate/water mixture. Experimental results show that the separation factor of PDMS membrane is largely improved by alkyl grafting because of the enhanced preferential sorption of ethyl acetate, and this improvement depends on alkyl grafting ratio and alkyl chain length. The total flux of PDMS membrane reduces after alkyl grafting owing to the decreased free volume. When grafting ratio is above 6.9%, membrane grafted with shorter alkyl groups is preferred for pervaporation. The best pervaporation performance is achieved by 9% octyl grafted PDMS membranes with a separation factor of 592 and a total flux of 188 gm−2 h−1 in separation of 1% ethyl acetate/water mixture at 40 °C. Moreover, this octyl grafted PDMS membrane also exhibits excellent separation performance in removal of butyl acetate, methyl‐tert‐butyl ether, and n‐butanol from water. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43700.
Semi‐IPN of biopolyurethane, benzyl starch, and cellulose nanofibers: Structure, thermal and mechanical properties
Authors: Haque Md Minhaz‐Ul , Oksman Kristiina 
Published: April 2016

ABSTRACTThe aim of this study was to develop bionanocomposites of biopolyurethane (PU), benzyl starch (BS), and cellulose nanofibers (CNF) with semi‐interpenetrating polymer network (S‐IPN) structure of improved properties. Morphology, thermal and mechanical properties of S‐IPN blends and nanocomposites were studied and compared with the neat polymers. Microscopy study showed that PU and BS were partially miscible as well as CNF were dispersed in both PU and BS phases in the nanocomposites. Dynamic mechanic thermal analysis demonstrated that BS decreased the tan δ peak of the PU while CNF increased it. The positive shifting of tan δ peak in the S‐IPN nanocomposite also indicated the presence of CNF in the PU phase. It was also noticed that S‐IPN nanocomposite displayed two tan δ peaks at higher temperature, indicating molecular interaction among BS, PU, and CNF. Furthermore, the S‐IPN nanocomposites displayed significantly higher E‐modulus and tensile strength compared with the neat PU. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43726.
Interfacial evaluation of epoxy/carbon nanofiber nanocomposite reinforced with glycidyl methacrylate treated UHMWPE fiber
Authors: Ahmadi Mojtaba , Masoomi Mahmood , Safi Somayeh , Zabihi Omid 
Published: April 2016

ABSTRACTInterface interactions of fiber–matrix play a crucial role in final performance of polymer composites. Herein, in situ polymerization of glycidyl methacrylate (GMA) on the ultrahigh molecular weight polyethylene (UHMWPE) fibers surface was proposed for improving the surface activity and adhesion property of UHMWPE fibers towards carbon nanofibers (CNF)‐epoxy nanocomposites. Chemical treatment of UHMWPE fibers was characterized by FTIR, XPS analysis, SEM, and microdroplet tests, confirming that the grafting of poly (GMA) chains on the surface alongside a significant synergy in the interfacial properties. SEM evaluations also exhibited cohesive type of failure for the samples when both GMA‐treated UHMWPE fiber and CNF were used to reinforce epoxy matrix. Compared with unmodified composite, a ∼319% increase in interfacial shear strength was observed for the samples reinforced with both 5 wt % GMA‐grafted UHMWPE and 0.5 wt % of CNF. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43751.
Molecular structure and storage hardening of natural rubber: Insight into the reactions between hydroxylamine and phospholipids linked to natural rubber molecule
Authors: Nimpaiboon Adun , Sriring Manus , Sakdapipanich Jitladda T. 
Published: April 2016

ABSTRACTThe effect of hydroxylamine on the molecular structure and storage hardening of natural rubber (NR) was investigated by the treatment of deproteinized NR (DPNR) latex with hydroxylamine. The hydroxylamine treatment decreased the content of long‐chain fatty acid ester groups in DPNR from about 2–0.7 mol per rubber molecule. The molecular weight and molecular weight distribution changed apparently after treatment with hydroxylamine. The relative intensity of the 1H NMR signals corresponding to phospholipids at the α‐terminal group decreased after the hydroxylamine treatment. The Huggins ‘k’ constant of hydroxylamine‐treated DPNR showed the liberation of linear rubber molecules caused by decomposition of branch points derived from phospholipids. The absence of storage hardening in hydroxylamine‐treated DPNR was observed to be caused by not only the reaction of hydroxylamine and aldehyde groups but also the removal of phospholipids as well as the breakdown of phospholipid aggregations as a result of hydroxylamime, contributing to the establishment of a newly proposed mechanism of hydroxylamine on the inhibition of storage hardening in NR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43753.
A Facile Molecular Precursor‐based Synthesis of Ag2Se Nanoparticles and Its Composites with TiO2 for Enhanced Photocatalytic Activity
Authors: Mishra Shashank , Du Dan , Jeanneau Erwann , Dappozze Frederic , Guillard Chantal , Zhang Jinlong , Daniele Stéphane 
Published: April 2016

AbstractThe reactions of different silver(I) reagents AgX (X−=iodide, trifluoroacetate, triflate) with selenoethers R2Se (R=Me, tBu) in a variety of solvents were investigated in relation with their use as precursors for Ag2Se nanomaterials. Different reaction conditions led to different reactivities and afforded either molecular complexes or metal selenide nanoparticles. The reactions leading to in situ formation of the metal selenide nanoparticles were then extended in the presence of commercial TiO2 (P25) to prepare silver selenide–titania nanocomposites with different Ag/Ti ratios. These nanocomposites, well characterized by elemental analysis (Ag, Se), PXRD, TEM, BET, XPS and UV/Vis studies, were investigated as photocatalysts for the degradation of formic acid (FA) solution. The xAg2Se‐TiO2 nanocomposites (x=0.01, 0.13 and 0.25 mol %) exhibited a much higher catalytic activity as compared to P25, which is an established benchmark for the photocatalysis under UV light, and retained a good photocatalytic stability after recycling for several times.
Metal–Organic‐Framework‐Templated Polyelectrolyte Nanocapsules for the Encapsulation and Delivery of Small‐Molecule–Polymer Conjugates
Authors: Liu Shuo , Chen Jianbin , Bao Xiaojia , Li Tao , Ling Yunyang , Li Chunxiang , Wu Chuanliu , Zhao Yibing 
Published: April 2016

AbstractHerein, we report a strategy for exploiting nanoscale metal–organic frameworks (nano‐MOFs) as templates for the layer‐by‐layer (LbL) assembly of polyelectrolytes. Because small‐molecule drugs or imaging agents cannot be efficiently encapsulated by polyelectrolyte nanocapsules, we investigated two promising and biocompatible polymers (comb‐shaped polyethylene glycol (PEG) and hyperbranched polyglycerol‐based PEG) for the conjugation of model drugs and imaging agents, which were then encapsulated inside the nano‐MOF‐templated nanocapsules. Furthermore, we also systemically explored the release kinetics of the encapsulated conjugates, and examined how the encapsulation and/or release processes could be controlled by varying the composition and architecture of the polymers. We envision that our nano‐MOFs‐templated nanocapsules, through combining with small‐molecule–polymer conjugates, will represent a new type of delivery system that could open up new opportunities for biomedical applications.
Trimethylammonium‐Derived Molecular Tweezers and Their Host–Guest Complexation Behaviours in Polar Media
Authors: Gao Zhao , Han Yifei , Chen Jiangjun , Wang Xiao , Wang Feng 
Published: April 2016

AbstractTrimethylammonium‐derived alkynylplatinum(II) terpyridine molecular tweezers have been designed and synthesized in this manuscript. They show moderate binding affinity towards the complementary organoplatinum guest in polar media, such as DMSO, methanol, and water, even though the guest itself is sparingly soluble in the latter two solvents. Responsive guest encapsulation/release from the cavity of molecular tweezers can be achieved by successive addition and removal of trifluoroacetic acid, accompanying with remarkable switching of the photophysical signals, which would benefit for the fabrication of intelligent supramolecular materials with tailored functionalities.
Superionic Conduction in Co‐Vacant P2‐NaxCoO2 Created by Hydrogen Reductive Elimination
Authors: Kato Kenichi , Kasai Hidetaka , Hori Akihiro , Takata Masaki , Tanaka Hiroshi , Kitagawa Susumu , Kobayashi Akira , Ozawa Nobuki , Kubo Momoji , Arikawa Hidekazu , Takeguchi Tatsuya , Sadakiyo Masaaki , Yamauchi Miho 
Published: April 2016

AbstractThe layered P2‐NaxMO2 (M: transition metal) system has been widely recognized as electronic or mixed conductor. Here, we demonstrate that Co vacancies in P2‐NaxCoO2 created by hydrogen reductive elimination lead to an ionic conductivity of 0.045 S cm−1 at 25 °C. Using in situ synchrotron X‐ray powder diffraction and Raman spectroscopy, the composition of the superionic conduction phase is evaluated to be Na0.61(H3O)0.18Co0.93O2. Electromotive force measurements as well as molecular dynamics simulations indicate that the ion conducting species is proton rather than hydroxide ion. The fact that the Co‐stoichiometric compound Nax(H3O)yCoO2 does not exhibit any significant ionic conductivity proves that Co vacancies are essential for the occurrence of superionic conductivity.
Investigation of binding properties of dicationic styrylimidazo[1,2‐a]pyridinium dyes to human serum albumin by spectroscopic techniques
Authors: Özdemir Ayşe , Gökoğlu Elmas , EsraYılmaz  , Yalçın Ergin , Gökoğlu Esra , Seferoğlu Zeynel , Tekinay Turgay 
Published: April 2016

AbstractThe binding interaction between two dicationic styrylimidazo[1,2‐a]pyridinium dyes and human serum albumin (HSA) was investigated at physiological conditions using fluorescence, UV–vis absorption, and circular dichroism (CD) spectroscopies. Analysis of the fluorescence titration data at different temperatures suggested that the fluorescence quenching mechanism of HSA by these dyes was static. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that hydrogen bonding and van der Waals forces played a major role in the formation of the dye–HSA complex. Binding distances (r) between dyes and HSA were calculated according to Förster's non‐radiative energy transfer theory. Studies of conformational changes of HSA using CD measurements indicate that the α‐helical content of the protein decreased upon binding of the dyes. Copyright © 2016 John Wiley & Sons, Ltd.
Crystal Structure of the HMG‐CoA Synthase MvaS from the Gram‐Negative Bacterium Myxococcus xanthus
Authors: Bock Tobias , Kasten Janin , Müller Rolf , Blankenfeldt Wulf 
Published: April 2016

AbstractA critical step in bacterial isoprenoid production is the synthesis of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) catalyzed by HMG‐CoA synthase (HMGCS). In myxobacteria, this enzyme is also involved in a recently discovered alternative and acetyl‐CoA‐dependent isovaleryl CoA biosynthesis pathway. Here we present crystal structures of MvaS, the HMGCS from Myxococcus xanthus, in complex with CoA and acetylated active site Cys115, with the second substrate acetoacetyl CoA and with the product of the condensation reaction, 3‐hydroxy‐3‐methylglutaryl CoA. With these structures, we show that MvaS uses the common HMGCS enzymatic mechanism and provide evidence that dimerization plays a role in the formation and stability of the active site. Overall, MvaS shows features typical of the eukaryotic HMGCS and exhibits differences from homologues from Gram‐positive bacteria. This study provides insights into myxobacterial alternative isovaleryl CoA biosynthesis and thereby extends the toolbox for the biotechnological production of renewable fuel and chemicals.
The Effects of Spacer Length and Composition on Aptamer‐Mediated Cell‐Specific Targeting with Nanoscale PEGylated Liposomal Doxorubicin
Authors: Xing Hang , Li Ji , Xu Weidong , Hwang Kevin , Wu Peiwen , Yin Qian , Li Zhensheng , Cheng Jianjun , Lu Yi 
Published: April 2016

AbstractAptamer‐based targeted drug delivery systems have shown significant promise for clinical applications. Although much progress has been made in this area, it remains unclear how PEG coating would affect the selective binding of DNA aptamers and thus influence the overall targeting efficiency. To answer this question, we herein report a systematic investigation of the interactions between PEG and DNA aptamers on the surface of liposomes by using a series of nanoscale liposomal doxorubicin formulations with different DNA aptamer and PEG modifications. We investigated how the spatial size and composition of the spacer molecules affected the targeting ability of the liposome delivery system. We showed that a spacer of appropriate length was critical to overcome the shielding from surrounding PEG molecules in order to achieve the best targeting effect, regardless of the spacer composition. Our findings provide important guidelines for the design of aptamer‐based targeted drug delivery systems.
Small‐Protein‐Stabilized Semiconductor Nanoprobe for Targeted Imaging of Cancer Cells
Authors: Zhao Ning , Liu Siyu , Jiang Qike , Lan Tian , Cheng Zhen , Liu Hongguang 
Published: April 2016

AbstractRecently, semiconductor nanoparticles such as quantum dots (QDs) have attracted significant attention for bioimaging. Complex chemical functionalization, surface modification, and bioconjugation chemistry are generally required to tag biomolecules to QDs for imaging of different biomarkers. In this study, we report a simple method for production of QDs stabilized by the small protein, Affibody (AF‐QDs) for fluorescent imaging of the human epidermal growth factor receptor type 2 (HER2) in human A549 lung cancer cells. This one‐pot synthesis of AF‐QDs avoids complex chemical conjugation procedures and demonstrates a promising approach for the preparation of fluorescent nanoprobes for imaging of cancer targets.
Photoactivation of an Acid‐Sensitive Ion Channel Associated with Vision and Pain
Authors: Shafaat Oliver S. , Winkler Jay R. , Gray Harry B. , Dougherty Dennis A. 
Published: April 2016

AbstractWe describe the reversible photoactivation of the acid sensitive ligand‐gated ion channel ASIC2a, a mammalian channel found throughout the central and peripheral nervous systems that is associated with vision and pain. We also show the activation of GLIC, an acid‐sensitive prokaryotic homologue of the nicotinic acetylcholine receptor. Photoactivation was achieved by using visible light irradiation of a newly synthesized water‐soluble merocyanine photoacid, 1, which was designed to remove adverse channel blocking effects of a related system. Activation of ASIC2a and GLIC occurs reversibly, in a benign manner, and only upon irradiation. Further studies using transient absorption spectroscopy showed that protonation of a colorimetric base occurred rapidly (ca. 100 μs) after excitation of 1. These results demonstrate that irradiation of 1 can induce rapid, local pH changes that can be used to investigate both biological and chemical proton transfer reactions.
Position‐Specific Mass Shift Analysis: A Systematic Method for Investigating the EI‐MS Fragmentation Mechanism of epi‐Isozizaene
Authors: Rabe Patrick , Klapschinski Tim A. , Dickschat Jeroen S. 
Published: April 2016

AbstractThe EI‐MS fragmentation mechanism of the bacterial sesquiterpene epi‐isozizaene was investigated through enzymatic conversion of all 15 synthetic (13C1)FPP isotopomers with the epi‐isozizaene synthase from Streptomyces albus and GC‐MS and GC‐QTOF analysis including MS‐MS. A systematic method, which we wish to call position‐specific mass shift analysis, for the identification of the full set of fragmentation reactions was developed.
Fluoroscopy pulse rate reduction during diagnostic and therapeutic imaging in the cardiac catheterization laboratory: An evaluation of radiation dose, procedure complications and outcomes
Authors: Hansen James W. , Foy Andrew , Schmidt Torrey , Ghahramani Mehrdad , Chambers Charles E. 
Published: April 2016

ObjectivesTo evaluate radiation reduction by reducing fluoroscopy pulse rate in diagnostic cardiac catheterizations and percutaneous coronary interventions (PCI) as well as outcomes at 30 days and six months.BackgroundRadiation exposure to the public at large has increased dramatically over the past three decades, and the cardiac catheterization laboratory is a large contributor. Fluoroscopy pulse rate is one way to decrease radiation exposure.MethodsFluoroscopy pulse rate was reduced from 10 pulses/sec (p/s) to 7.5 p/s as part of an internal quality improvement project. A retrospective analysis of all cardiac catheterizations was performed, evaluating Air KERMA at the interventional reference point (Ka, r), Air KERMA area product (PKA), procedural complications and major adverse cardiac events at 30 days and 6 months.ResultsIn diagnostic catheterization median PKA (µGy·m2) and Ka,r (mGy) were significantly reduced (PKA – 5,613.3 vs. 4,400, P < 0.001; Ka,r – 703.0 vs. 621.0, P = 0.041). In PCI, median PKA and Ka,r were further reduced (PKA – 13,481.6 vs. 10,648.0, P < 0.001; Ka,r – 1787.0 vs. 1,459.0, P = 0.002). There was no difference in complications, fluoroscopy time or number of stents placed. There was no difference in MACE after adjustment for number of STEMIs.ConclusionsReducing fluoroscopy pulse rates to 7.5 from 10 is an effective way to reduce patient radiation exposure across meaningful dose indices. A pulse rate of 7.5 p/s is safe, with no difference in complications or outcomes. A fluoroscopy pulse rate of 7.5 p/s should be given strong consideration for a new standard. © 2016 Wiley Periodicals, Inc.
Hybrid Spinel Oxides/N‐Doped Reduced Graphene Oxide as Highly‐Active Bifunctional Electrocatalysts for Oxygen Reduction/Evolution Reactions
Authors: He Xiaobo , Yin Fengxiang , Yuan Shuo , Liu Ning , Huang Xiaofeng 
Published: April 2016

AbstractA series of Co3O4–MnCo2O4/N‐doped reduced graphene oxide (CMO/N‐rGO) electrocatalysts with different N‐rGO content were developed by using a two‐step synthetic method. The electrocatalysts were characterized by X‐ray diffraction, scanning electron microscopy/transmission electron microscopy, and X‐ray photoelectron spectroscopy. Their catalytic activities toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were evaluated by linear‐sweep voltammetry (LSV) in an alkaline electrolyte. It is found that GO is vital for the formation of CMO/N‐rGO nanocomposite during the preparation. The CMO hybrid nanoparticles can be obtained through feeding GO during the preparation, but only the single spinel oxide, i.e. MnCo2O4, is formed without adding GO, even if the feeding molar ratio of Co and Mn (Co/Mn) is higher than 2. The CMO/N‐rGO nanocomposite electrocatalysts can efficiently take advantages of ORR and OER active sites from the CMO hybrid oxides and N‐rGO, as well as the enhanced charge transfer from N‐rGO, thus bringing about higher bifunctional activities towards ORR/OER in alkaline electrolyte, as compared with Co3O4, MnCo2O4, and N‐rGO. The CMO/N‐rGO nanocomposites are considered to be promising bifunctional electrocatalysts for ORR/OER.
In Situ Infrared Study of the Electrooxidation of Ethanol and Acetaldehyde in Acid Electrolyte
Authors: Torrero Jorge , Pérez‐Alonso Francisco J. , Peña Miguel A. , Domínguez Carlota , Al‐Youbi Abdulrahman O. , Al‐Thabaiti Shaeel A. , Basahel Sulaiman N. , Alshehri Abdulmohsen A. , Rojas Sergio 
Published: April 2016

AbstractThe electrooxidation of ethanol and acetaldehyde on Pt/C has been studied by using in situ IR spectroscopy. To identify the species formed during the electrooxidation reactions accurately, the IR spectra were collected in both HClO4/H2O and HClO4/D2O electrolytes. The results shown herein reveal that ethanol adsorbs on Pt at low potentials in a series of dehydrogenative steps that lead to η2‐acetaldehyde prior to the scission of the C−C bond, which takes place at potentials higher than 150 mV. At potentials of approximately 220 mV, the Pt surface is fully covered by COad (and C1,ad) species, which thus impede further ethanol adsorption. At higher potentials, when OHad species are nucleated, COad is oxidized to CO2, which releases Pt sites for further ethanol adsorption and oxidation. However, due to the presence of OHad species, ethanol oxidation to acetic acid is the preferred reaction pathway. In contrast, the C−C bond of acetaldehyde is broken at 50 mV, which leads to the formation of a full monolayer of CO and CHx adsorbed species on Pt. The IR spectra collected in an electrolyte that contained D2O show no evidence for the formation of acetyl species prior to the scission of the C−C bond.
Assembly of a Metal–Organic Framework into 3 D Hierarchical Porous Monoliths Using a Pickering High Internal Phase Emulsion Template
Authors: Zhu He , Zhang Qi , Zhu Shiping 
Published: April 2016

Abstract3D Hierarchical porous metal–organic framework (MOF) monoliths are prepared by using Pickering high internal phase emulsion (HIPE) template. Pickering HIPEs were stabilized solely by UiO‐66 MOF particles with internal phase up to 90 % of the volume. The effects of internal phase type and volume, as well as MOF particle concentration on the stability of resulting Pickering HIPEs were investigated. Furthermore, by adding small amount of polyvinyl alcohol (PVA) as binder or polymerization in the continuous aqueous phase, followed by freeze‐drying, two types of MOF‐based 3D hierarchical porous monoliths with ultralow density (as low as 12 mg cm−3) were successfully prepared. This Pickering HIPE template approach provides a facile and practical way for assembling of MOFs into complex structures.