bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Structural Characterization of Three Unique Helicobacter pylori α‐Cholesteryl Phosphatidyl Glucosides
Authors: Nguyen Huy Q. , Davis Ryan A. , Gervay‐Hague Jacquelyn 
Published: September 2014

AbstractSteryl glycosides produced by bacteria play important biological roles in the evasion and modulation of host immunity. Step‐economical syntheses of three cholesteryl‐6‐O‐phosphatidyl‐α‐D‐glucopyranosides (αCPG) unique to Helicobacter pylori have been achieved. The approach relies upon regioselective deprotection of per‐O‐trimethylsilyl‐α‐D‐cholesterylglucoside at C6 followed by phosphoramidite coupling. Global TMS ether deprotection in the presence of oxygen and subsequent deprotection of the cyano ethyl phosphoester afforded the target compounds in 16–21 % overall yield starting from D‐glucose. The structures of these natural products were determined using a combination of 2D NMR methods and mass spectrometry. These robust synthesis and characterization protocols provide analogues to facilitate glycolipidomic profiling and biological studies.
Polydimethylsiloxane: A General Matrix for High‐Performance Chromatographic NMR Spectroscopy
Authors: Huang Shaohua , Gao Jun , Wu Rui , Li Shengying , Bai Zhengwu 
Published: September 2014

AbstractThe detection and structural characterization of the components of a mixture is a challenging task. Therefore, the development of a facile and general method that enables both the separation and the structural characterization of the components is desired. Diffusion‐ordered NMR spectroscopy (DOSY) with the aid of a matrix is a promising tool for this purpose. However, because the currently existing matrices only separate limited components, the application of the DOSY technique is restricted. Herein we introduce a new versatile matrix, poly(dimethylsiloxane), which can fully separate many mixtures of different structural types by liquid‐state NMR spectroscopy. With poly(dimethylsiloxane), liquid‐state chromatographic NMR spectroscopy could become a general approach for the structural elucidation of mixtures of compounds.
Synthesis of Polyketide Stereoarrays Enabled by a Traceless Oxonia‐Cope Rearrangement
Authors: Yang Lin , He Guoli , Yin Ruifeng , Zhu Lili , Wang Xiaoxia , Hong Ran 
Published: September 2014

AbstractPolyketide antibiotics bearing skipped polyols represent a synthetic challenge. A SiCl4‐promoted oxonia‐Cope rearrangement of syn,syn‐2‐vinyl‐1,3‐diols was developed to forge an array of 1,5‐pentenediols, thus providing versatile motifs for the preparation of 1,2,3,5‐stereoarrays in a highly stereoselective manner. Further exploration with Sn(OTf)2 realized the rearrangement of a cross‐aldehyde which tactically warrants the utility of the current approach to access complex polyketides. The origin of high stereoselectivity is attributed to a chairlike anti‐conformation of the oxonium ion intermediate.
A General Entry to Antifeedant Sesterterpenoids: Total Synthesis of (+)‐Norleucosceptroid A, (−)‐Norleucosceptroid B, and (−)‐Leucosceptroid K
Authors: Hugelshofer Cedric L. , Magauer Thomas 
Published: September 2014

AbstractThe first asymmetric total synthesis of the antifeedant terpenoids (+)‐norleucosceptroid A, (−)‐norleucosceptroid B, and (−)‐leucosceptroid K has been accomplished. This highly concise synthetic route was guided by our efforts to develop a platform for the collective synthesis of a whole family of antifeedant natural products. The synthesis features a Hauser–Kraus‐type annulation followed by an unprecedented, highly efficient intramolecular dilactol aldol‐type condensation reaction to produce the 5,6,5 skeleton. The developed synthetic route proceeds for norleucosceptroid A and B in 16 steps (longest linear sequence) from known compounds.
Self‐Replication and Amplification of Enantiomeric Excess of Chiral Multifunctionalized Large Molecules by Asymmetric Autocatalysis
Authors: Kawasaki Tsuneomi , Nakaoda Mai , Takahashi Yutaro , Kanto Yusuke , Kuruhara Nanako , Hosoi Kenji , Sato Itaru , Matsumoto Arimasa , Soai Kenso 
Published: September 2014

AbstractSelf‐replication of large chiral molecular architectures is one of the great challenges and interests in synthetic, systems, and prebiotic chemistry. Described herein is a new chemical system in which large chiral multifunctionalized molecules possess asymmetric autocatalytic self‐replicating and self‐improving abilities, that is, improvement of their enantioenrichment in addition to the diastereomeric ratio. The large chiral multifunctionalized molecules catalyze the production of themselves with the same structure, including the chirality of newly formed asymmetric carbon atoms, in the reaction of the corresponding achiral aldehydes and reagent. The chirality of the large multifunctionalized molecules controlled the enantioselectivity of the reaction in a highly selective manner to construct multiple asymmetric stereogenic centers in a single reaction.
In Vivo Residue‐Specific Dopa‐Incorporated Engineered Mussel Bioglue with Enhanced Adhesion and Water Resistance
Authors: Yang Byeongseon , Ayyadurai Niraikulam , Yun Hyungdon , Choi Yoo Seong , Hwang Byeong Hee , Huang Jun , Lu Qingye , Zeng Hongbo , Cha Hyung Joon 
Published: September 2014

AbstractMisaminoacylation of 3,4‐dihydroxyphenylalanine (Dopa) molecules to tRNATyr by endogenous tyrosyl‐tRNA synthetase allowed the quantitative replacement of tyrosine residues with a yield of over 90 % by an in vivo residue‐specific incorporation strategy, to create, for the first time, engineered mussel adhesive proteins (MAPs) in Escherichia coli with a very high Dopa content, close to that of natural MAPs. The Dopa‐incorporated MAPs exhibited a superior surface adhesion and water resistance ability by assistance of Dopa‐mediated interactions including the oxidative Dopa cross‐linking, and furthermore, showed underwater adhesive properties comparable to those of natural MAPs. These results propose promising use of Dopa‐incorporated engineered MAPs as bioglues or adhesive hydrogels for practical underwater applications.
A Layered Hybrid Perovskite Solar‐Cell Absorber with Enhanced Moisture Stability
Authors: Smith Ian C. , Hoke Eric T. , Solis‐Ibarra Diego , McGehee Michael D. , Karunadasa Hemamala I. 
Published: September 2014

AbstractTwo‐dimensional hybrid perovskites are used as absorbers in solar cells. Our first‐generation devices containing (PEA)2(MA)2[Pb3I10] (1; PEA=C6H5(CH2)2NH3+, MA=CH3NH3+) show an open‐circuit voltage of 1.18 V and a power conversion efficiency of 4.73 %. The layered structure allows for high‐quality films to be deposited through spin coating and high‐temperature annealing is not required for device fabrication. The 3D perovskite (MA)[PbI3] (2) has recently been identified as a promising absorber for solar cells. However, its instability to moisture requires anhydrous processing and operating conditions. Films of 1 are more moisture resistant than films of 2 and devices containing 1 can be fabricated under ambient humidity levels. The larger bandgap of the 2D structure is also suitable as the higher bandgap absorber in a dual‐absorber tandem device. Compared to 2, the layered perovskite structure may offer greater tunability at the molecular level for material optimization.
Reglucosylation of the Benzoxazinoid DIMBOA with Inversion of Stereochemical Configuration is a Detoxification Strategy in Lepidopteran Herbivores
Authors: Wouters Felipe C. , Reichelt Michael , Glauser Gaétan , Bauer Eugen , Erb Matthias , Gershenzon Jonathan , Vassão Daniel G. 
Published: September 2014

AbstractBenzoxazinoids are chemical defenses against herbivores and are produced by many members of the grass family. These compounds are stored as stable glucosides in plant cells and require the activity of glucosidases to release the corresponding toxic aglucones. In maize leaves, the most abundant benzoxazinoid is (2R)‐DIMBOA‐Glc, which is converted into the toxic DIMBOA upon herbivory. The ways in which three Spodoptera species metabolize this toxin were investigated. (2S)‐DIMBOA‐Glc, an epimer of the initial plant compound, was observed in the insect frass, and the associated glucosyltransferase activity was detected in the insect gut tissue. The epimeric glucoside produced by the insect was found to be no longer reactive towards plant glucosidases and thus cannot be converted into a toxin. Stereoselective reglucosylation thus represents a detoxification strategy in Spodoptera species that might help to explain their success as agricultural pests on benzoxazinoid‐containing crops.
Dissecting Ubiquitin Signaling with Linkage‐Defined and Protease Resistant Ubiquitin Chains
Authors: Schneider Tatjana , Schneider Daniel , Rösner Daniel , Malhotra Saurav , Mortensen Franziska , Mayer Thomas U. , Scheffner Martin , Marx Andreas 
Published: September 2014

AbstractUbiquitylation is a complex posttranslational protein modification and deregulation of this pathway has been associated with different human disorders. Ubiquitylation comes in different flavors: Besides mono‐ubiquitylation, ubiquitin chains of various topologies are formed on substrate proteins. The fate of ubiquitylated proteins is determined by the linkage‐type of the attached ubiquitin chains, however, the underlying mechanism is poorly characterized. Herein, we describe a new method based on codon expansion and click‐chemistry‐based polymerization to generate linkage‐defined ubiquitin chains that are resistant to ubiquitin‐specific proteases and adopt native‐like functions. The potential of these artificial chains for analyzing ubiquitin signaling is demonstrated by linkage‐specific effects on cell‐cycle progression.
Epitaxial Seeded Growth of Rare‐Earth Nanocrystals with Efficient 800 nm Near‐Infrared to 1525 nm Short‐Wavelength Infrared Downconversion Photoluminescence for In Vivo Bioimaging
Authors: Wang Rui , Li Xiaomin , Zhou Lei , Zhang Fan 
Published: September 2014

AbstractNovel β‐NaGdF4/Na(Gd,Yb)F4:Er/NaYF4:Yb/NaNdF4:Yb core/shell 1/shell 2/shell 3 (C/S1/S2/S3) multi‐shell nanocrystals (NCs) have been synthesized and used as probes for in vivo imaging. They can be excited by near‐infrared (800 nm) radiation and emit short‐wavelength infrared (SWIR, 1525 nm) radiation. Excitation at 800 nm falls into the “biological transparency window”, which features low absorption by water and low heat generation and is considered to be the ideal excitation wavelength with the least impact on biological tissues. After coating with phospholipids, the water‐soluble NCs showed good biocompatibility and low toxicity. With efficient SWIR emission at 1525 nm, the probe is detectable in tissues at depths of up to 18 mm with a low detection threshold concentration (5 nM for the stomach of nude mice and 100 nM for the stomach of SD rats). These results highlight the potential of the probe for the in vivo monitoring of areas that are otherwise difficult to analyze.
Effects of dual impeller system of Rushton turbine, concave disk turbine and their combinations on the performance of kojic acid fermentation by Aspergillus flavus Link 44‐1
Authors: Suhaili Nurashikin , Tan Joo Shun , Mohamed Mohd‐Shamzi , Halim Murni , Ariff A.B. 
Published: September 2014

AbstractIn the present work, the effects of dual impeller configurations comprising of Rushton turbine (RT) and Concave‐bladed disk turbine (CD‐6) on the oxygen transfer profile and fermentation performance of kojic acid production by Aspergillus flavus Link 44‐1 was investigated. Batch cultivations of A. flavus Link 44‐1 were performed in 2 L stirred tank bioreactor. The fermentations were conducted using different dual impeller systems; (1) RT‐RT, (2) CD6‐CD6, (3) RT‐CD6, and (4) CD6‐RT (bottom‐top impeller). It was perceived that dual CD‐6 system was able to improve oxygen transfer rate by about 25–45% over the hybrids of RT and CD‐6 and the typically configured dual RT system. While no substantial disparity could be seen on the fungal growth rate by the manipulation of the impeller, high concentration of kojic acid (44.93 g L−1) was attained with the use of dual CD‐6 as the mixer. Efficient agitating system that can facilitate good gas dispersion capability is crucially required in order to counteract the problem of oxygen solubility limitation faced in such viscous fungal fermentation broth. The results from this work suggested the promising capability of dual CD‐6 configuration in enhancing productivity of kojic acid fermentation in stirred tank bioreactor. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Influences of different gravity environments on the curing process and cured products of carbon‐nanotube‐reinforced epoxy composites
Authors: Li Defeng , Liu Yuyan , Wang Youshan , Kang Hongjun , Wang Lei , Tan Huifeng 
Published: September 2014

ABSTRACTThe influences of different gravity environments on the curing process and the cured products of carbon‐nanotube‐reinforced epoxy composites were investigated in this study. Different gravity environments were simulated with a superconducting magnet on the basis of which resin matrix composites with different amino‐functionalized multiwalled carbon nanotube (NH2‐MWCNT) concentrations of 0.1, 0.3, 0.5, and 1 wt % were tested. Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, thermomechanical analysis (TMA), thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and three‐point bending tests were used to analyze the characteristics of different curing processes and cured products. From the results, we observed that the curing rate of the epoxy composites was influenced by different gravity values, and there was anisotropy in the NH2‐MWCNT‐reinforced epoxy composites cured in the simulated microgravity environment. More effects of gravity on the curing process and cured products could be obtained through detailed experiments and discussion; this is important and fundamental for improving and enhancing the properties of composite materials used in different gravity environments. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41413.
Effects of mold cavity temperature on surface quality and mechanical properties of nanoparticle‐filled polymer in rapid heat cycle molding
Authors: Zhang Aimin , Zhao Guoqun , Guan Yanjin 
Published: September 2014

ABSTRACTAcrylonitrile‐butadiene‐styrene (ABS)/poly methyl methacrylate (PMMA) and ABS/PMMA/nano‐CaCO3 composites were prepared in a corotating twin screw extruder. Single‐gate and double‐gate samples were molded based on a rapid heat cycle molding (RHCM) system. Effects of mold cavity temperature on surface quality and mechanical properties of single‐gate and double‐gate samples in RHCM process were conducted. The results showed that surface quality of plastic parts can be improved significantly by increasing mold cavity temperature. Nano‐CaCO3 particles on the surface of plastic parts can be eliminated by using high mold cavity temperature. The roughness and gloss of two kinds of plastic parts (ABS/PMMA and ABS/PMMA/nano‐CaCO3) stabilized at the same level when the mold cavity temperature is above glass transition temperature of resin material. Weld line can be eliminated in RHCM process during high mold cavity temperature. The tensile strength of both ABS/PMMA and ABS/PMMA/nano‐CaCO3 exhibited decreasing trend with the increase of mold cavity temperature. Reduction of internal stress gave rise to the increase of Izod impact strength of ABS/PMMA for both sing‐gate and double‐gate samples. However, influence regularity of mold cavity temperature on Izod impact strength of ABS/PMMA/nano‐CaCO3 is depended on the number of gates. For all the samples in this study, too high of mold cavity temperature (higher than 125°C) deprave Izod impact strength of plastic parts. Both ABS/PMMA and ABS/PMMA/nano‐CaCO3 are not susceptible to weld line. When the mold surface temperature is approximately equal to glass transition temperature of resin material, all the samples are found to give the best combination of properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41420.
Fragmentation and drying ratchet down Great Plains stream fish diversity
Authors: Perkin Joshuah S. , Gido Keith B. , Costigan Katie H. , Daniels Melinda D. , Johnson Eric R. 
Published: September 2014

Abstract

Stream fragmentation alters the structure of aquatic communities on a global scale, generally through loss of native species. Among riverscapes in the Great Plains of North America, stream fragmentation and hydrologic alteration (flow regulation and dewatering) are implicated in the decline of native fish diversity.
This study documents the spatio–temporal distribution of fish reproductive guilds in the fragmented Arkansas and Ninnescah rivers of south‐central Kansas using retrospective analyses involving 63 years of fish community data.
Pelagic‐spawning fishes declined throughout the study area during 1950–2013, including Arkansas River shiner (Notropis girardi) last reported in 1983, plains minnow (Hybognathus placitus) in 2006, and peppered chub (Macrhybopsis tetranema) in 2012. Longitudinal patterns in fish community structure in both rivers consisted of strong breaks associated with dams, and pelagic‐spawning fishes were missing from shorter fragments upstream of those barriers. Among downstream and longer fragments, probability of occurrence for pelagic‐spawning fishes declined or fell to zero during periods of drought.
Based on these data, interactions between fragmentation and drying are hypothesized as operating as an ecological ratchet mechanism in which forward movement toward pelagic‐spawning fish extirpation occurs during desiccation, and reciprocated reverse movement toward recolonization following return of flows is blocked by fragmentation.
The ratchet mechanism is capable of explaining the long‐term 'ratcheting down' of fish diversity in Great Plains rivers and has implications for managing biodiversity in fragmented riverscapes where water is scarce or might become so in the future.
Copyright © 2014 John Wiley & Sons, Ltd.
A Single 2‐(2′‐Hydroxyphenyl)benzothiazole Derivative Can Achieve Pure White‐Light Emission
Authors: Cheng Jinling , Liu Di , Bao Lijun , Xu Kai , Yang Yang , Han Keli 
Published: September 2014

AbstractThe synthesis and photophysics of two novel 2‐(2′‐hydroxyphenyl)benzothiazole (HBT) derivatives are presented. The electron‐withdrawing trifluoromethyl (CF3) group in compound 1 facilitates the deprotonation of the phenolic hydroxy group. Well‐resolved triple fluorescence from the enol, keto, and phenolic anion, which ranges from 350 to 600 nm, was detected for 1 in ethanol, which marks the first time triple fluorescence from an excited‐state intramolecular proton transfer (ESIPT) molecule has been reported. Both triphenylamine and CF3 were introduced into derivative 2. Intramolecular charge transfer and the “red‐edge effect” resulted in the bathochromic shift of dual fluorescence of 2. Triple fluorescence was also observed for 2 in ethanol. In mixed acetonitrile and ethanol, pure white‐light emission with CIE coordinates of (0.33, 0.33) and a quantum yield of 0.25 was achieved for 2. This work provides a new avenue for the rational design of an ESIPT molecule to achieve white‐light generation under mild conditions.
Noncovalent immobilization of cellulases using the reversibly soluble polymers for biopolishing of cotton fabric
Authors: Yu Yuanyuan , Yuan Jiugang , Wang Qiang , Fan Xuerong , Wang Ping , Cui Li 
Published: September 2014

AbstractThe hydrolytic reaction of cellulases can occur in the interior of cellulosic fibers, causing tensile strength loss of the fabrics. Cellulase immobilization is an approach to solve this problem, because enlarging the molecule size of cellulases will limit the hydrolysis to the surfaces of the fibers. In this study, commercial cellulases were noncovalently immobilized onto the reversibly soluble polymers (Eudragit S‐100 and Eudragit L‐100). The characteristics of cellulase‐Eudragit S‐100 (CES) and cellulase‐Eudragit L‐100 (CEL) were evaluated using Fourier transform infrared spectra, circular dichroism spectra, and fluorescence spectra. The CES showed higher stability than CEL and free cellulase, especially at higher pH and temperature. CES and CEL retained 51% and 42% of their original activities after three cycles of repeated uses, respectively. In addition, the effects of cellulase treatment on the cotton yarn and fabric have been investigated. The bending stiffness results showed that the cotton fabric samples treated with the free and immobilized cellulases were softer than untreated samples. However, less fiber damage in terms of weight loss and tensile strength of treated cotton was observed.
Dermatan sulfate epimerase 1 deficient mice as a model for human abdominal wall defects
Authors: Gustafsson Renata , Stachtea Xanthi , Maccarana Marco , Grottling Emma , Eklund Erik , Malmström Anders , Oldberg Åke 
Published: September 2014

BackgroundDermatan sulfate (DS) is a highly sulfated polysaccharide with a variety of biological functions in extracellular matrix organization and processes such as tumorigenesis and wound healing. A distinct feature of DS is the presence of iduronic acid, produced by the two enzymes, DS‐epimerase 1 and 2, which are encoded by Dse and Dsel, respectively.MethodsWe have previously shown that Dse knockout (KO) mice in a mixed C57BL/6–129/SvJ background have an altered collagen matrix structure in skin. In the current work we studied Dse KO mice in a pure NFR genetic background.ResultsDse KO embryos and newborns had kinked tails and histological staining revealed significantly thicker epidermal layers in Dse KO mice when compared with heterozygote (Het) or wild‐type (WT) littermates. Immunochemical analysis of the epidermal layers in newborn pups showed increased expression of keratin 5 in the basal layer and keratin 1 in the spinous layer. In addition, we observed an abdominal wall defect with herniated intestines in 16% of the Dse KO embryos. Other, less frequent, developmental defects were exencephaly and spina bifida.ConclusionWe conclude that the combination of defective collagen structure in the dermis and imbalanced keratinocyte maturation could be responsible for the observed developmental defects in Dse KO mice. In addition, we propose that Dse KO mice could be used as a model in pathogenetic studies of human fetal abdominal wall defects. Birth Defects Research (Part A) 100:712–720, 2014. © 2014 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.
Corruptible social agents
Authors: Gutierrez‐Garcia J. Octavio , Rodríguez Luis‐Felipe 
Published: September 2014

AbstractAgent‐based virtual simulations of social systems susceptible to corruption (e.g., police agencies) require agents capable of exhibiting corruptible behaviors to achieve realistic simulations and enable the analysis of corruption as a social problem. This paper proposes a formal belief‐desire‐intention framework supported by the functional event calculus and fuzzy logic for modeling corruption based on the integrity level of social agents and the influence of corrupters on them. Corruptible social agents are endowed with beliefs, desires, intentions, and corrupt‐prone plans to achieve their desires. This paper also proposes a fuzzy logic system to define the level of impact of corruption‐related events on the degree of belief in the truth of anti‐corruption factors (e.g., the integrity of the leader of an organization). Moreover, an agent‐based model of corruption supported by the proposed belief‐desire‐intention framework and the fuzzy logic system was devised and implemented. Results obtained from agent‐based simulations are consistent with actual macro‐level patterns of corruption reported in the literature. The simulation results show that (i) the bribery rate increases as more external entities attempt to bribe agents and (ii) the more anti‐corruption factors agents believe to be true, the less prone to perpetrate acts of corruption. Copyright © 2014 John Wiley & Sons, Ltd.