bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hybrid Ultra‐Microporous Materials for Selective Xenon Adsorption and Separation
Authors: Mohamed Mona H. , Elsaidi Sameh K. , Pham Tony , Forrest Katherine A. , Schaef Herbert T. , Hogan Adam , Wojtas Lukasz , Xu Wenqian , Space Brian , Zaworotko Michael J. , Thallapally Praveen K. 
Published: May 2016

AbstractThe demand for Xe/Kr separation continues to grow due to the industrial significance of high‐purity Xe gas. Current separation processes rely on energy intensive cryogenic distillation. Therefore, less energy intensive alternatives, such as physisorptive separation, using porous materials, are required. Herein we show that an underexplored class of porous materials called hybrid ultra‐microporous materials (HUMs) affords new benchmark selectivity for Xe separation from Xe/Kr mixtures. The isostructural materials, CROFOUR‐1‐Ni and CROFOUR‐2‐Ni, are coordination networks that have coordinatively saturated metal centers and two distinct types of micropores, one of which is lined by CrO42− (CROFOUR) anions and the other is decorated by the functionalized organic linker. These nets offer unprecedented selectivity towards Xe. Modelling indicates that the selectivity of these nets is tailored by synergy between the pore size and the strong electrostatics afforded by the CrO42− anions.
Capture and Recycling of Sortase A through Site‐Specific Labeling with Lithocholic Acid
Authors: Rosen Christian B. , Kwant Richard L. , MacDonald James I. , Rao Meera , Francis Matthew B. 
Published: May 2016

AbstractEnzyme‐mediated protein modification often requires large amounts of biocatalyst, adding significant costs to the process and limiting industrial applications. Herein, we demonstrate a scalable and straightforward strategy for the efficient capture and recycling of enzymes using a small‐molecule affinity tag. A proline variant of an evolved sortase A (SrtA 7M) was N‐terminally labeled with lithocholic acid (LA)—an inexpensive bile acid that exhibits strong binding to β‐cyclodextrin (βCD). Capture and recycling of the LA‐Pro‐SrtA 7M conjugate was achieved using βCD‐modified sepharose resin. The LA‐Pro‐SrtA 7M conjugate retained full enzymatic activity, even after multiple rounds of recycling.
A Concise Route to the Strongylophorines
Authors: Yu Wanwan , Hjerrild Per , Overgaard Jacob , Poulsen Thomas B. 
Published: May 2016

AbstractAn efficient eight‐step semisynthesis of strongylophorine‐2 from the abundant building block isocupressic acid is reported. The route represents the first synthetic entry into this class of natural products and provides access to six additional family members. A novel iron(III)‐mediated rearrangement–cyclization cascade and a directed photochemical sp3 C−H δ‐lactonization are the key transformations that enable concise assembly of these bioactive polycyclic meroterpenoids.
Isolating Reactions at the Picoliter Scale: Parallel Control of Reaction Kinetics at the Liquid–Liquid Interface
Authors: Phan‐Quang Gia Chuong , Lee Hiang Kwee , Ling Xing Yi 
Published: May 2016

AbstractMiniaturized liquid–liquid interfacial reactors offer enhanced surface area and rapid confinement of compounds of opposite solubility, yet they are unable to provide in situ reaction monitoring at a molecular level at the interface. A picoreactor operative at the liquid–liquid interface is described, comprising plasmonic colloidosomes containing Ag octahedra strategically assembled at the water‐in‐decane emulsion interface. The plasmonic colloidosomes isolate ultrasmall amounts of solutions (<200 pL), allowing parallel monitoring of multiple reactions simultaneously. Using the surface‐enhanced Raman spectroscopy (SERS) technique, in situ monitoring of the interfacial protonation of dimethyl yellow (p‐dimethylaminoazobenzene (DY)) is performed, revealing an apparent rate constant of 0.09 min−1 for the first‐order reaction. The presence of isomeric products with similar physical properties is resolved, which would otherwise be indiscernible by other analytical methods.
General Self‐Template Synthesis of Transition‐Metal Oxide and Chalcogenide Mesoporous Nanotubes with Enhanced Electrochemical Performances
Authors: Wang Huan , Zhuo Sifei , Liang Yu , Han Xiling , Zhang Bin 
Published: May 2016

AbstractThe development of a general strategy for synthesizing hierarchical porous transition‐metal oxide and chalcogenide mesoporous nanotubes, is still highly challenging. Herein we present a facile self‐template strategy to synthesize Co3O4 mesoporous nanotubes with outstanding performances in both the electrocatalytic oxygen‐evolution reaction (OER) and Li‐ion battery via the thermal‐oxidation‐induced transformation of cheap and easily‐prepared Co‐Asp(cobalt–aspartic acid) nanowires. The initially formed thin layers on the precursor surfaces, oxygen‐induced outward diffusion of interior precursors, the gas release of organic oxidation, and subsequent Kirkendall effect are important for the appearance of the mesoporous nanotubes. This self‐template strategy of low‐cost precursors is found to be a versatile method to prepare other functional mesoporous nanotubes of transition‐metal oxides and chalcogenides, such as NiO, NiCo2O4, Mn5O8, CoS2 and CoSe2.
Palladium(II)‐Catalyzed Tandem Synthesis of Acenes Using Carboxylic Acids as Traceless Directing Groups
Authors: Kim Kiho , Vasu Dhananjayan , Im Honggu , Hong Sungwoo 
Published: May 2016

AbstractA straightforward synthetic strategy for generating useful anthracene derivatives was developed involving palladium(II)‐catalyzed tandem transformation with carboxylic acids as traceless directing groups. Carboxyl‐directed C‐H alkenylation, carboxyl‐directed secondary C‐H activation and rollover, intramolecular C−C bond formation, and decarboxylative aromatization are proposed as the key steps in the tandem reaction pathway. This novel synthetic route utilizes a broad range of substrates and provides a convenient synthetic tool that allows access to acenes.
Mesoporous Silica Particles Integrated with All‐Inorganic CsPbBr3 Perovskite Quantum‐Dot Nanocomposites (MP‐PQDs) with High Stability and Wide Color Gamut Used for Backlight Display
Authors: Wang Hung‐Chia , Lin Shin‐Ying , Tang An‐Cih , Singh Bheeshma Pratap , Tong Hung‐Chun , Chen Ching‐Yi , Lee Yu‐Chun , Tsai Tzong‐Liang , Liu Ru‐Shi 
Published: May 2016

AbstractAll‐inorganic CsPbX3 (X=I, Br, Cl) perovskite quantum dots (PQDs) have been investigated because of their optical properties, such as tunable wavelength, narrow band, and high quantum efficiency. These features have been used in light emitting diode (LED) devices. LED on‐chip fabrication uses mixed green and red quantum dots with silicone gel. However, the ion‐exchange effect widens the narrow emission spectrum. Quantum dots cannot be mixed because of anion exchange. We address this issue with a mesoporous PQD nanocomposite that can prevent ion exchange and increase stability. We mixed green quantum‐dot‐containing mesoporous silica nanocomposites with red PQDs, which can prevent the anion‐exchange effect and increase thermal and photo stability. We applied the new PQD‐based LEDs for backlight displays. We also used PQDs in an on‐chip LED device. Our white LED device for backlight display passed through a color filter with an NTSC value of 113 % and Rec. 2020 of 85 %.
Resistance of Cu(Aβ4–16) to Copper Capture by Metallothionein‐3 Supports a Function for the Aβ4–42 Peptide as a Synaptic CuII Scavenger
Authors: Wezynfeld Nina E. , Stefaniak Ewelina , Stachucy Kinga , Drozd Agnieszka , Płonka Dawid , Drew Simon C. , Krężel Artur , Bal Wojciech 
Published: May 2016

AbstractAβ4‐42 is a major species of Aβ peptide in the brains of both healthy individuals and those affected by Alzheimer's disease. It has recently been demonstrated to bind CuII with an affinity approximately 3000 times higher than the commonly studied Aβ1‐42 and Aβ1‐40 peptides, which are implicated in the pathogenesis of Alzheimer's disease. Metallothionein‐3, a protein considered to orchestrate copper and zinc metabolism in the brain and provide antioxidant protection, was shown to extract CuII from Aβ1‐40 when acting in its native Zn7MT‐3 form. This reaction is assumed to underlie the neuroprotective effect of Zn7MT‐3 against Aβ toxicity. In this work, we used the truncated model peptides Aβ1‐16 and Aβ4‐16 to demonstrate that the high‐affinity CuII complex of Aβ4‐16 is resistant to Zn7MT‐3 reactivity. This indicates that the analogous complex of the full‐length peptide Cu(Aβ4‐42) will not yield copper to MT‐3 in the brain, thus supporting the concept of a physiological role for Aβ4‐42 as a CuII scavenger in the synaptic cleft.
Electrochemical C−H/N−H Functionalization for the Synthesis of Highly Functionalized (Aza)indoles
Authors: Hou Zhong‐Wei , Mao Zhong‐Yi , Zhao Huai‐Bo , Melcamu Yared Yohannes , Lu Xin , Song Jinshuai , Xu Hai‐Chao 
Published: May 2016

AbstractIndoles and azaindoles are among the most important heterocycles because of their prevalence in nature and their broad utility in pharmaceutical industry. Reported herein is an unprecedented noble‐metal‐ and oxidant‐free electrochemical method for the coupling of (hetero)arylamines with tethered alkynes to synthesize highly functionalized indoles, as well as the more challenging azaindoles.
Stabilizing a Platinum1 Single‐Atom Catalyst on Supported Phosphomolybdic Acid without Compromising Hydrogenation Activity
Authors: Zhang Bin , Asakura Hiroyuki , Zhang Jia , Zhang Jiaguang , De Sudipta , Yan Ning 
Published: May 2016

AbstractIn coordination chemistry, catalytically active metal complexes in a zero‐ or low‐valent state often adopt four‐coordinate square‐planar or tetrahedral geometry. By applying this principle, we have developed a stable Pt1 single‐atom catalyst with a high Pt loading (close to 1 wt %) on phosphomolybdic acid(PMA)‐modified active carbon. This was achieved by anchoring Pt on the four‐fold hollow sites on PMA. Each Pt atom is stabilized by four oxygen atoms in a distorted square‐planar geometry, with Pt slightly protruding from the oxygen planar surface. Pt is positively charged, absorbs hydrogen easily, and exhibits excellent performance in the hydrogenation of nitrobenzene and cyclohexanone. It is likely that the system described here can be extended to a number of stable SACs with superior catalytic activities.
A Binuclear 1,1′‐Bis(boratabenzene) Complex: Unprecedented Intramolecular Metal–Metal Communication through a B−B Bond
Authors: Braunschweig Holger , Demeshko Serhiy , Ewing William C. , Krummenacher Ivo , Macha Bret B. , Mattock James D. , Meyer Franc , Mies Jan , Schäfer Marius , Vargas Alfredo 
Published: May 2016

AbstractWe report the synthesis of the first 1,1′‐bis(boratabenzene) species by tetrabromodiborane(4)‐induced ring‐expansion reactions of cobaltocene. Six equivalents of cobaltocene are required as the species plays the dual role of reagent and reductant to yield [{(η5‐C5H5)Co}2{μ:η6,η6‐(BC5H5)2}]. The formally dianionic bis(boratabenzene) moiety with a boron–boron single bond can be viewed as a symmetric dimer of the parent boratabenzene anion as well as the first example of a diboron analogue of biphenyl. The solution electrochemistry of the bimetallic complex shows four stepwise redox events, indicating significant intramolecular interaction between the cobalt ions across the 1,1′‐bis(boratabenzene) unit. The magnetic properties, as investigated by variable‐temperature SQUID magnetometry, reveal weak intramolecular antiferromagnetic interactions. Density functional theory calculations support the experimental results and add insight into the various electronic states of the complex.
C−C Coupling of Benzyl Fluorides Catalyzed by an Electrophilic Phosphonium Cation
Authors: Zhu Jiangtao , Pérez Manuel , Stephan Douglas W. 
Published: May 2016

AbstractThe activation and cleavage of benzyl fluorides by the electrophilic organofluorophosphonium catalyst, [(C6F5)3PF][B(C6F5)4], is reported and used for the preparation of 1,1‐diarylalkanes (37 examples) and substituted aryl homoallylic alkenes (14 examples). This procedure involves mild conditions, avoids harmful waste, and is compatible with a range of substituted arenes and allylic silanes.
Flexible polyurethane foams modified with biobased polyols: Synthesis and physical‐chemical characterization
Authors: Soto G. D. , Marcovich N. E. , Mosiewicki M. A. 
Published: May 2016

ABSTRACTA series of flexible polyurethane foams with different polyol compositions were synthesized through the replacement of a portion of the petroleum‐based polyether polyol with biobased polyols, namely, glycerol (GLY) and hydroxylated methyl esters (HMETO). HMETO was synthesized by the alkaline transesterification of tung oil (TO; obtaining GLY as a byproduct) and the subsequent hydroxylation of the obtained methyl esters with performic acid generated in situ. FTIR spectroscopy, 1H‐NMR, and different analytical procedures indicated that the hydroxyl content increased significantly and the molecular weight decreased with respect to those of the TO after the two reaction steps. The characterization of the obtained foams, achieved through the measurement of the characteristic reaction times, thermal and dynamic mechanical analysis, scanning electronic microscopy, and density measurements, is reported and discussed. The most important changes in the modified foams were found with the addition of GLY to the formulation; this led to an increased foam density and storage rubbery modulus, which were associated with a higher crosslinking density because of the decrease in the chain length between crosslinking points. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43831.
Effects of compatibilizer on the morphological, mechanical, and rheological properties of poly(methyl methacrylate)/poly(N‐methyl methacrylimide) blends
Authors: Kim Ji Mun , Jang Myung Geun , Park Dong Hyup , Kim Woo Nyon 
Published: May 2016

ABSTRACTThe effects of compatibilizer on the morphological, thermal, mechanical, and rheological properties of poly(methyl methacrylate) (PMMA)/poly(N‐methyl methacrylimide) (PMMI) (70/30) blends were investigated. The compatibilizer used in this study was styrene–acrylonitrile–glycidyl methacrylate (SAN‐GMA) copolymer. Morphological characterization of the PMMA/PMMI (70/30) blend with SAN‐GMA showed a decrease in PMMI droplet size with an increase in SAN‐GMA. The glass‐transition temperature of the PMMA‐rich phase became higher when SAN‐GMA was added up to 5 parts per hundred resin by weight (phr). The flexural and tensile strengths of the PMMA/PMMI (70/30) blend increased with the addition of SAN‐GMA up to 5 phr. The complex viscosity of the PMMA/PMMI (70/30) blends increased when SAN‐GMA was added up to 5 phr, which implies an increase in compatibility between the PMMA and PMMI components. From the weighted relaxation spectrum, which was obtained from the storage modulus and loss modulus, the interfacial tension of the PMMA/PMMI (70/30) blend was calculated using the Palierne emulsion model and the Choi‐Schowalter model. The results of the morphological, thermal, mechanical, and rheological studies and the values of the interfacial tension of the PMMA/PMMI (70/30) blends suggest that the optimum compatibilizer concentration of SAN‐GMA is 5 phr. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43856.
Climate‐friendly polyurethane blowing agent based on a carbon dioxide adduct from palmitic acid grafted polyethyleneimine
Authors: Long Yuanzhu , Sun Fuhua , Liu Chao , Huang Dong , Xie Xingyi 
Published: May 2016

ABSTRACTTo explore a new blowing agent for polyurethanes (PUs), palmitic acid was grafted onto a branched polyethyleneimine (bPEI; weight‐average molecular weight = 25,000 Da) via N,N′‐carbonyldiimidazole condensation to form a hydrophobically modified bPEI [palmitic acid grafted branched polyethyleneimine (C16–bPEI)] with a grafting rate of 12%. A CO2 adduct of C16–bPEI, which trapped 16.8% CO2 in it, was synthesized from C16–bPEI. The long alkyl chain grafting improved the dispersibility of the CO2 adduct in the PU raw materials and favored a homogeneous release of CO2 to blow PUs during the exothermic foaming process. The preliminary results show that the foams possessed a density of 72.0 kg/m3 and a compressive strength of 246 kPa; this matched the required values of foams for the thermal insulation of underground steel pipes. This new blowing agent emitted nothing but CO2 to the atmosphere, so it will not promote ozone depletion and will avoid global warming problems that are associated with traditional blowing agents such as chlorofluorocarbons and hydrochloroflourocarbons. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43874.
Finite‐Time Stabilization of a Class of Cascade Nonlinear Switched Systems
Authors: Su Qingyu , Jia Xiaolong , Liu Honghai 
Published: May 2016

AbstractThis paper investigates the finite‐time stabilization problem for a class of cascade nonlinear switched systems. Using the average dwell time and multiple Lyapunov function technologies, some sufficient conditions to guarantee that the corresponding closed‐loop system is finite‐time stabilized are derived for the switched systems. Via multiple Lyapunov functions, the state feedback controller is designed to finite‐time stabilize a cascade nonlinear switched system, and the conditions are formulated in terms of linear matrix inequalities. An example is given to illustrate the efficiency of the proposed methods.
Spectroscopic studies on the interaction of chromium (VI) and chromium (III) with keyhole limpet hemocyanin
Authors: Fan Yulan , Zeng Guidi , Liu Jingyi , Chen Huifang , Xue Jun , Wu Yongquan , Li Xun 
Published: May 2016

AbstractThe interactions of keyhole limpet hemocyanin (KLH) with chromium nitrate, potassium dichromate, and chromate were investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy under simulated physiological conditions. The experimental results showed that the different forms of chromium could quench the intrinsic fluorescence of KLH following a static quenching mechanism rather than by dynamic collision, which indicated that a Cr–KLH complex was formed. The Stern–Volmer quenching constants for the interaction indicated that the binding reaction of KLH with Cr(VI) was stronger the binding of KLH with Cr(III). The thermodynamic values for binding of Cr(VI) to KLH areΔH > 0 andΔS > 0. By contrast, the values for the interaction of Cr(III) with KLH areΔH < 0 andΔS < 0. The results of synchronous fluorescence, UV–vis absorption and CD spectroscopy showed that theα‐helical secondary structure and conformation of KLH were altered by different forms of chromium. Copyright © 2016 John Wiley & Sons, Ltd.
Optimization of an acetate reduction pathway for producing cellulosic ethanol by engineered yeast
Authors: Zhang Guo‐Chang , Kong In Iok , Wei Na , Peng Dairong , Turner Timothy L. , Sung Bong Hyun , Sohn Jung‐Hoon , Jin Yong‐Su 
Published: May 2016

ABSTRACTXylose fermentation by engineered Saccharomyces cerevisiae expressing NADPH‐linked xylose reductase (XR) and NAD+‐linked xylitol dehydrogenase (XDH) suffers from redox imbalance due to cofactor difference between XR and XDH, especially under anaerobic conditions. We have demonstrated that coupling of an NADH‐dependent acetate reduction pathway with surplus NADH producing xylose metabolism enabled not only efficient xylose fermentation, but also in situ detoxification of acetate in cellulosic hydrolysate through simultaneous co‐utilization of xylose and acetate. In this study, we report the highest ethanol yield from xylose (0.463 g ethanol/g xylose) by engineered yeast with XR and XDH through optimization of the acetate reduction pathway. Specifically, we constructed engineered yeast strains exhibiting various levels of the acetylating acetaldehyde dehydrogenase (AADH) and acetyl‐CoA synthetase (ACS) activities. Engineered strains exhibiting higher activities of AADH and ACS consumed more acetate and produced more ethanol from a mixture of 20 g/L of glucose, 80 g/L of xylose, and 8 g/L of acetate. In addition, we performed environmental and genetic perturbations to further improve the acetate consumption. Glucose‐pulse feeding to continuously provide ATPs under anaerobic conditions did not affect acetate consumption. Promoter truncation of GPD1 and gene deletion of GPD2 coding for glycerol‐3‐phosphate dehydrogenase to produce surplus NADH also did not lead to improved acetate consumption. When a cellulosic hydrolysate was used, the optimized yeast strain (SR8A6S3) produced 18.4% more ethanol and 41.3% less glycerol and xylitol with consumption of 4.1 g/L of acetate than a control strain without the acetate reduction pathway. These results suggest that the major limiting factor for enhanced acetate reduction during the xylose fermentation might be the low activities of AADH and ACS, and that the redox imbalance problem of XR/XDH pathway can be exploited for in situ detoxification of acetic acid in cellulosic hydrolysate and increasing ethanol productivity and yield. Biotechnol. Bioeng. 2016;113: 2587–2596. © 2016 Wiley Periodicals, Inc.
Development of simultaneous analysis of tryptophan metabolites in serum and gastric juice – an investigation towards establishing a biomarker test for gastric cancer diagnosis
Authors: Choi Jong Min , Park Won Sang , Song Kyo Young , Lee Hwa Jeong , Jung Byung Hwa 
Published: May 2016

AbstractTo evaluate changes in tryptophan metabolism and discover diagnostic biomarkers for gastric cancer, a quantitative method was developed for tryptophan and its seven metabolites (indole‐3‐lactic acid, anthranilic acid, serotonin, nicotinic acid, kynurenic acid, kynurenine and 3‐indoxyl sulfate) in both human serum and gastric juice using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Serum and gastric juice were prepared with a simple protein precipitation using aqueous 0.1% formic acid and acetonitrile. As a result, it was found that the kynurenine pathway of tryptophan metabolism was activated in gastric cancer and that the metabolic ratio of kynurenine/tryptophan, which reflects the enzyme activity of indoleamine‐2,3‐dioxygenase, was associated with the observed metabolic changes. Finally, the investigation of tryptophan metabolites, especially kynurenic acid, in serum and gastric juice might serve as biomarkers for gastric cancer. The findings in this study provide critical information of tryptophan metabolism which can be applied to a serum‐based diagnostic test for gastric cancer.