bluuebunny/crossref_metadata_2025_split huggingface dataset:
Halogenase‐inspirierte oxidative Chlorierung mittels Flavin‐ Photokatalyse
Authors: Hering Thea , Mühldorf Bernd , Wolf Robert , König Burkhard 
Published: March 2016

AbstractChlorierte Arene sind Bestandteil vieler Pharmazeutika, Agrochemikalien und Polymere sowie wichtige Startmaterialien für übergangsmetallkatalysierte Kreuzkupplungen. Für ihre Herstellung nutzen Chemiker meist Chlorgas oder elektropositive Chlorierungsreagentien. Die Natur hingegen chloriert ausgehend von Chloridionen mithilfe von FAD‐abhängigen Halogenasen und O2 als Oxidationsmittel. Wir beschreiben hier eine diesem enzymatischen Prozess nachempfundene photokatalytische oxidative Chlorierung unter Verwendung des organischen Farbstoffes Riboflavintetraacetat. Dieses chemische Verfahren ermöglicht die Umsetzung von Arenen innerhalb eines definierten Redoxbereichs und hat eine größere Substratbreite als die Aktivierung durch eine substratspezifische Enzymbindungstasche.
Construction of an Artificial Ferrimagnetic Lattice by Lithium Ion Insertion into a Neutral Donor/Acceptor Metal–Organic Framework
Authors: Taniguchi Kouji , Narushima Keisuke , Mahin Julien , Kosaka Wataru , Miyasaka Hitoshi 
Published: March 2016

AbstractConstruction of a molecular system in which the magnetic lattice exhibits long‐range order is one of the fundamental goals in materials science. In this study, we demonstrate the artificial construction of a ferrimagnetic lattice by doping electrons into acceptor sites of a neutral donor/acceptor metal–organic framework (D/A‐MOF). This doping was achieved by the insertion of Li‐ions into the D/A‐MOF, which was used as the cathode of a Li‐ion battery cell. The neutral D/A‐MOF is a layered system composed of a carboxylate‐bridged paddlewheel‐type diruthenium(II,II) complex as the donor and a TCNQ derivative as the acceptor. The ground state of the neutral form was a magnetically disordered paramagnetic state. Upon discharge of the cell, spontaneous magnetization was induced; the transition temperature was variable. The stability of the magnetically ordered lattice depended on the equilibrium electric potential of the D/A‐MOF cathode, which reflected the electron‐filling level.
Electrocatalytic Hydrogen Production by a Nickel(II) Complex with a Phosphinopyridyl Ligand
Authors: Tatematsu Ryo , Inomata Tomohiko , Ozawa Tomohiro , Masuda Hideki 
Published: March 2016

AbstractA novel nickel(II) complex [Ni(L)2Cl]Cl with a bidentate phosphinopyridyl ligand 6‐((diphenylphosphino)methyl)pyridin‐2‐amine (L) was synthesized as a metal‐complex catalyst for hydrogen production from protons. The ligand can stabilize a low Ni oxidation state and has an amine base as a proton transfer site. The X‐ray structure analysis revealed a distorted square‐pyramidal NiII complex with two bidentate L ligands in a trans arrangement in the equatorial plane and a chloride anion at the apex. Electrochemical measurements with the NiII complex in MeCN indicate a higher rate of hydrogen production under weak acid conditions using acetic acid as the proton source. The catalytic current increases with the stepwise addition of protons, and the turnover frequency is 8400 s−1 in 0.1 m [NBu4][ClO4]/MeCN in the presence of acetic acid (290 equiv) at an overpotential of circa 590 mV.
Transparent Aluminium Oxide Coatings of Polymer Brushes
Authors: Micciulla Samantha , Duan XiaoFei , Strebe Julia , Löhmann Oliver , Lamb Robert N. , von Klitzing Regine 
Published: March 2016

AbstractA novel method for the preparation of transparent Al2O3 coatings of polymers is presented. An environmental‐friendly sol–gel method is employed, which implies mild conditions and low costs. A thermoresponsive brush is chosen as a model surface. X‐ray photoelectron spectroscopy is used to characterize the samples during the conversion of the precursor Al(OH)3 into oxide and to prove the mildness of the protocol. The study evidences a relation between lateral homogeneity of alumina and the wettability of the polymer surface by the precursor solution, while morphology and elasticity are dominated by the polymer properties. The study of the swelling behavior of the underneath brush reveals the absence of water uptake, proving the impermeability of the alumina layer. The broad chemical and structural variety of polymers, combined with the robustness of transparent alumina films, makes these composites promising as biomedical implants, protective sheets and components for electric and optical devices.
Block Copolymerization of Lactide and an Epoxide Facilitated by a Redox Switchable Iron‐Based Catalyst
Authors: Biernesser Ashley B. , Delle Chiaie Kayla R. , Curley Julia B. , Byers Jeffery A. 
Published: March 2016

AbstractA cationic iron(III) complex was active for the polymerization of various epoxides, whereas the analogous neutral iron(II) complex was inactive. Cyclohexene oxide polymerization could be “switched off” upon in situ reduction of the iron(III) catalyst and “switched on” upon in situ oxidation, which is orthogonal to what was observed previously for lactide polymerization. Conducting copolymerization reactions in the presence of both monomers resulted in block copolymers whose identity can be controlled by the oxidation state of the catalyst: selective lactide polymerization was observed in the iron(II) oxidation state and selective epoxide polymerization was observed in the iron(III) oxidation state. Evidence for the formation of block copolymers was obtained from solubility differences, GPC, and DOSY‐NMR studies.
Direct Time‐Domain Observation of Conformational Relaxation in Gas‐Phase Cold Collisions
Authors: Drayna Garrett K. , Hallas Christian , Wang Kenneth , Domingos Sergio R. , Eibenberger Sandra , Doyle John M. , Patterson David 
Published: March 2016

AbstractCooling molecules in the gas phase is important for precision spectroscopy, cold molecule physics, and physical chemistry. Measurements of conformational relaxation cross sections shed important light on potential energy surfaces and energy flow within a molecule. However, gas‐phase conformational cooling has not been previously observed directly. In this work, we directly observe conformational dynamics of 1,2‐propanediol in cold (6 K) collisions with atomic helium using microwave spectroscopy and buffer‐gas cooling. Precise knowledge and control of the collisional environment in the buffer‐gas allows us to measure the absolute collision cross‐section for conformational relaxation. Several conformers of 1,2‐propanediol are investigated and found to have relaxation cross‐sections with He ranging from σ=4.7(3.0)×10−18 cm2 to σ>5×10−16 cm2. Our method is applicable to a broad class of molecules and could be used to provide information about the potential energy surfaces of previously uninvestigated molecules.
Multicompartmental Microcapsules with Orthogonal Programmable Two‐Way Sequencing of Hydrophobic and Hydrophilic Cargo Release
Authors: Xu Weinan , Ledin Petr A. , Iatridi Zacharoula , Tsitsilianis Constantinos , Tsukruk Vladimir V. 
Published: March 2016

AbstractMulticompartmental responsive microstructures with the capability for the pre‐programmed sequential release of multiple target molecules of opposite solubility (hydrophobic and hydrophilic) in a controlled manner have been fabricated. Star block copolymers with dual‐responsive blocks (temperature for poly(N‐isopropylacrylamide) chains and pH for poly(acrylic acid) and poly(2‐vinylpyridine) arms) and unimolecular micellar structures serve as nanocarriers for hydrophobic molecules in the microcapsule shell. The interior of the microcapsule can be loaded with water‐soluble hydrophilic macromolecules. For these dual‐loaded microcapsules, a programmable and sequential release of hydrophobic and hydrophilic molecules from the shell and core, respectively, can be triggered independently by temperature and pH variations. These stimuli affect the hydrophobicity and chain conformation of the star block copolymers to initiate out‐of‐shell release (elevated temperature), or change the overall star conformation and interlayer interactions to trigger increased permeability of the shell and out‐of‐core release (pH). Reversing stimulus order completely alters the release process.
Compact, Polyvalent Mannose Quantum Dots as Sensitive, Ratiometric FRET Probes for Multivalent Protein–Ligand Interactions
Authors: Guo Yuan , Sakonsinsiri Chadamas , Nehlmeier Inga , Fascione Martin A. , Zhang Haiyan , Wang Weili , Pöhlmann Stefan , Turnbull W. Bruce , Zhou Dejian 
Published: March 2016

AbstractA highly efficient cap‐exchange approach for preparing compact, dense polyvalent mannose‐capped quantum dots (QDs) has been developed. The resulting QDs have been successfully used to probe multivalent interactions of HIV/Ebola receptors DC‐SIGN and DC‐SIGNR (collectively termed as DC‐SIGN/R) using a sensitive, ratiometric Förster resonance energy transfer (FRET) assay. The QD probes specifically bind DC‐SIGN, but not its closely related receptor DC‐SIGNR, which is further confirmed by its specific blocking of DC‐SIGN engagement with the Ebola virus glycoprotein. Tuning the QD surface mannose valency reveals that DC‐SIGN binds more efficiently to densely packed mannosides. A FRET‐based thermodynamic study reveals that the binding is enthalpy‐driven. This work establishes QD FRET as a rapid, sensitive technique for probing structure and thermodynamics of multivalent protein–ligand interactions.
Crafting Core/Graded Shell–Shell Quantum Dots with Suppressed Re‐absorption and Tunable Stokes Shift as High Optical Gain Materials
Authors: Jung Jaehan , Lin Chun Hao , Yoon Young Jun , Malak Sidney T. , Zhai Yaxin , Thomas Edwin L. , Vardeny Valy , Tsukruk Vladimir V. , Lin Zhiqun 
Published: March 2016

AbstractThe key to utilizing quantum dots (QDs) as lasing media is to effectively reduce non‐radiative processes, such as Auger recombination and surface trapping. A robust strategy to craft a set of CdSe/Cd1−xZnxSe1−ySy/ZnS core/graded shell–shell QDs with suppressed re‐absorption, reduced Auger recombination rate, and tunable Stokes shift is presented. In sharp contrast to conventional CdSe/ZnS QDs, which have a large energy level mismatch between CdSe and ZnS and thus show strong re‐absorption and a constrained Stokes shift, the as‐synthesized CdSe/Cd1−xZnxSe1−ySy/ZnS QDs exhibited the suppressed re‐absorption of CdSe core and tunable Stokes shift as a direct consequence of the delocalization of the electron wavefunction over the entire QD. Such Stokes shift‐engineered QDs with suppressed re‐absorption may represent an important class of building blocks for use in lasers, light emitting diodes, solar concentrators, and parity‐time symmetry materials and devices.
Generation and Reaction of Carbamoyl Anions in Flow: Applications in the Three‐Component Synthesis of Functionalized α‐Ketoamides
Authors: Nagaki Aiichiro , Takahashi Yusuke , Yoshida Jun‐ichi 
Published: March 2016

AbstractUsing a flow microreactor system, carbamoyllithium compounds were successfully generated and used for reactions with electrophiles to give various amides, including α‐ketoamides. The present method could be applied to the three‐component synthesis of functionalized α‐ketoamides using a carbamoyllithium compound, methyl chloroformate, and a functionalized organolithium reagent.
Surface modification and immobilization in poly(acrylic acid) of Ag/ZnO for photocatalytic degradation of endocrine‐disrupting compounds
Authors: Jasso‐Salcedo Alma Berenice , Meimaroglou Dimitrios , Hoppe Sandrine , Pla Fernand , Escobar‐Barrios Vladimir A. 
Published: March 2016

ABSTRACTSilver‐modified ZnO particles (Ag/ZnO) are effective catalysts for the photodegradation of water pollutants such as bisphenol‐A. However, until now, their use in continuous processes was back‐drawn because of difficulties associated with their recovery. To overcome this problem, the present work aimed at immobilizing Ag/ZnO in cross‐linked poly(acrylic acid) ‐PAA‐. Ag/ZnO was first silanized using (3‐glycidyloxypropyl)trimethoxysilane and thoroughly dispersed in a water‐acrylic acid solution. The suspension was then submitted to radical polymerization in presence of a cross‐linker (N,N′‐Methylenebisacrylamide). The resulting composites were characterized in terms of chemical structure, morphology, crystallinity, thermal properties, and photostability. Their analyses showed that the silanized particles were chemically anchored to PAA and homogeneously distributed in the matrix. UV‐assisted photocatalysis of bisphenol‐A aqueous solutions showed that immobilized Ag/ZnO can achieve photodegradation performances comparable to pure Ag/ZnO and allows its use in successive cycles and, consequently, in continuous processes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43528.
Preparation and hemocompatibility of electrospun O‐carboxymethyl chitosan/PVA nanofibers
Authors: Zeng Qinghuan , Qin Jinmin , Yin Xueqiong , Liu Haifang , Zhu Li , Dong Wenyuan , Zhang Song 
Published: March 2016

ABSTRACTChitosan was deacetylated and carboxymethylated to prepare O‐carboxymethyl chitosan (CMC) for further electrospinning. CMC was characterized using FTIR, NMR, and chemical titration, indicating a degree of carboxymethylation of 51.4%. CMC was electrospun together with poly(vinyl alcohol) (PVA) to prepare membranes composed of nanofibers. The electrospinning conditions were optimized. The CMC/PVA membrane obtained at the conditions of 15.2 g/mL CMC 50 mL, 8 g/mL PVA 5 mL, 25 kV, and a distance of 23 cm, had nanofibers without beads, with diameters of 70–200 nm. The mats were crosslinked by glutaraldehyde before platelet adhesion measurement. The nanofibrous structure remained after crosslinking while the wettability decreased. CMC/PVA mats with higher CMC amount and fewer beads, had fewer adherent platelets and less platelets aggregation showing better hemocompatibility. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43565.
Freestanding Ag2S/CuS PVA films with improved dielectric properties for organic electronics
Authors: Aippunny Ann Mary K. , Shamsudeen Sajna M. , Valparambil Prakashan , Mathew Siby , Vishwambharan Unnikrishnan N. 
Published: March 2016

ABSTRACTThe prime goal of this work is to synthesize free‐standing polyvinyl alcohol (PVA) films doped with Ag2S, CuS, Ag2S/CuS alloy, and Ag2S/CuS nanocomposites through the sol–gel route. The dependence of Ag2S content in the PVA nanocomposite films on both the real and imaginary parts of the complex permittivity and loss tangent values was examined. An enhanced dielectric constant was achieved with minimum dielectric loss due to the insulating silica layer. By changing the Ag2S content in Ag2S/CuS PVA films, the AC conductivity is improved with pure Ag2S nanoparticles exhibiting highest values of the order of 10−6−10−9 S/cm. The Cole–Cole parameters were calculated and the semicircles observed in the plots indicate a single relaxation process. The results suggest that these composite films are potential materials for embedded capacitor applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43568.
Improving Accuracy on Bayesian Inference Problems Using a Brief Tutorial
Authors: Talboy Alaina N. , Schneider Sandra L. 
Published: March 2016

AbstractResearch suggests that most people struggle when asked to interpret the outcomes of diagnostic tests such as those presented as Bayesian inference problems. To help people interpret these difficult problems, we created a brief tutorial, requiring less than 10 minutes, that guided participants through the creation of an aid (either graph or table) based on an example inference problem and then showed the correct way to calculate the positive predictive value of the problem (i.e., likelihood that positive tests correctly indicate presence of condition). Approximately 70% of those in each training condition found the correct response on at least one problem in the format for which they were trained. Just under 55% of those in the control condition (i.e., no training) were able to find the correct response on at least one table or graph problem. We demonstrated a relationship between numeracy and performance on both problem formats, although we did not find evidence for a relationship between graph literacy and performance for either problem format. Potential improvements to and applications of the tutorial are discussed. Copyright © 2016 John Wiley & Sons, Ltd.
Membrane‐mediated regulation of vascular identity
Authors: Hashimoto Takuya , Tsuneki Masayuki , Foster Trenton R. , Santana Jeans M. , Bai Hualong , Wang Mo , Hu Haidi , Hanisch Jesse J. , Dardik Alan 
Published: March 2016

AbstractVascular diseases span diverse pathology, but frequently arise from aberrant signaling attributed to specific membrane‐associated molecules, particularly the Eph‐ephrin family. Originally recognized as markers of embryonic vessel identity, Eph receptors and their membrane‐associated ligands, ephrins, are now known to have a range of vital functions in vascular physiology. Interactions of Ephs with ephrins at cell‐to‐cell interfaces promote a variety of cellular responses such as repulsion, adhesion, attraction, and migration, and frequently occur during organ development, including vessel formation. Elaborate coordination of Eph‐ and ephrin‐related signaling among different cell populations is required for proper formation of the embryonic vessel network. There is growing evidence supporting the idea that Eph and ephrin proteins also have postnatal interactions with a number of other membrane‐associated signal transduction pathways, coordinating translation of environmental signals into cells. This article provides an overview of membrane‐bound signaling mechanisms that define vascular identity in both the embryo and the adult, focusing on Eph‐ and ephrin‐related signaling. We also discuss the role and clinical significance of this signaling system in normal organ development, neoplasms, and vascular pathologies. Birth Defects Research (Part C) 108:65–84, 2016. © 2016 Wiley Periodicals, Inc.
Comparison of batch and continuous multi‐column protein A capture processes by optimal design
Authors: Baur Daniel , Angarita Monica , Müller‐Späth Thomas , Steinebach Fabian , Morbidelli Massimo 
Published: March 2016

AbstractMulti‐column capture processes show several advantages compared to batch capture. It is however not evident how many columns one should use exactly. To investigate this issue, twin‐column CaptureSMB, 3‐ and 4‐column periodic counter‐current chromatography (PCC) and single column batch capture are numerically optimized and compared in terms of process performance for capturing a monoclonal antibody using protein A chromatography. Optimization is carried out with respect to productivity and capacity utilization (amount of product loaded per cycle compared to the maximum amount possible), while keeping yield and purity constant. For a wide range of process parameters, all three multi‐column processes show similar maximum capacity utilization and performed significantly better than batch. When maximizing productivity, the CaptureSMB process shows optimal performance, except at high feed titers, where batch chromatography can reach higher productivity values than the multi‐column processes due to the complete decoupling of the loading and elution steps, albeit at a large cost in terms of capacity utilization. In terms of trade‐off, i.e. how much the capacity utilization decreases with increasing productivity, CaptureSMB is optimal for low and high feed titers, whereas the 3‐column process is optimal in an intermediate region. Using these findings, the most suitable process can be chosen for different production scenarios.
Stability‐indicating chromatographic methods for determination of flecainide acetate in the presence of its degradation products; isolation and identification of two of its impurities
Authors: El‐Ragehy Nariman A. , Hassan Nagiba Y. , Tantawy Mahmoud A. , Abdelkawy Mohamed 
Published: March 2016

AbstractIn this work, two stability‐indicating chromatographic methods have been developed and validated for determination of flecainide acetate (an antiarrhythmic drug) in the presence of its degradation products (flecainide impurities; B and D). Flecainide acetate was subjected to a stress stability study including acid, alkali, oxidative, photolytic and thermal degradation. The suggested chromatographic methods included the use of thin layer chromatography (TLC‐densitometry) and high‐performance liquid chromatography (HPLC). The TLC method employed aluminum TLC plates precoated with silica gel G.F254 as the stationary phase and methanol–ethyl acetate–33% ammonia (3:7:0.3, by volume) as the mobile phase. The chromatograms were scanned at 290 nm and visualized in daylight by the aid of iodine vapor. The developed HPLC method used a RP‐C18 column with isocratic elution. Separation was achieved using a mobile phase composed of phosphate buffer pH 3.3–acetonitrile–triethylamine (53:47:0.03, by volume) at a flow rate of 1.0 mL/min and UV detection at 292 nm. Factors affecting the efficiency of HPLC method have been studied carefully to reach the optimum conditions for separation. The developed methods were validated according to the International Conference on Harmonization guidelines and were applied for bulk powder and dosage form. Copyright © 2016 John Wiley & Sons, Ltd.
Recombinant horseradish peroxidase variants for targeted cancer treatment
Authors: Bonifert Günther , Folkes Lisa , Gmeiner Christoph , Dachs Gabi , Spadiut Oliver 
Published: March 2016

AbstractCancer is a major cause of death. Common chemo‐ and radiation‐therapies damage healthy tissue and cause painful side effects. The enzyme horseradish peroxidase (HRP) has been shown to activate the plant hormone indole‐3‐acetic acid (IAA) to a powerful anticancer agent in in vitro studies, but gene directed enzyme prodrug therapy (GDEPT) studies showed ambivalent results. Thus, HRP/IAA in antibody directed enzyme prodrug therapy (ADEPT) was investigated as an alternative. However, this approach has not been intensively studied, since the enzyme preparation from plant describes an undefined mixture of isoenzymes with a heterogenic glycosylation pattern incompatible with the human system. Here, we describe the recombinant production of the two HRP isoenzymes C1A and A2A in a Pichia pastoris benchmark strain and a glyco‐engineered strain with a knockout of the α‐1,6‐mannosyltransferase (OCH1) responsible for hypermannosylation. We biochemically characterized the enzyme variants, tested them with IAA and applied them on cancer cells. In the absence of H2O2, HRP C1A turned out to be highly active with IAA, independent of its surface glycosylation. Subsequent in vitro cytotoxicity studies with human T24 bladder carcinoma and MDA‐MB‐231 breast carcinoma cells underlined the applicability of recombinant HRP C1A with reduced surface glycoslyation for targeted cancer treatment. Summarizing, this is the first study describing the successful use of recombinantly produced HRP for targeted cancer treatment. Our findings might pave the way for an increased use of the powerful isoenzyme HRP C1A in cancer research in the future.