bluuebunny/crossref_metadata_2025_split huggingface dataset:
How Photoisomerization Drives Peptide Folding and Unfolding: Insights from QM/MM and MM Dynamics Simulations
Authors: Xia Shu‐Hua , Cui Ganglong , Fang Wei‐Hai , Thiel Walter 
Published: January 2016

AbstractPhotoswitchable azobenzene cross‐linkers can control the folding and unfolding of peptides by photoisomerization and can thus regulate peptide affinities and enzyme activities. Using quantum mechanics/molecular mechanics (QM/MM) methods and classical MM force fields, we report the first molecular dynamics simulations of the photoinduced folding and unfolding processes in the azobenzene cross‐linked FK‐11 peptide. We find that the interactions between the peptide and the azobenzene cross‐linker are crucial for controlling the evolution of the secondary structure of the peptide and responsible for accelerating the folding and unfolding events. They also modify the photoisomerization mechanism of the azobenzene cross‐linker compared with the situation in vacuo or in solution.
P,S Ligands for the Asymmetric Construction of Quaternary Stereocenters in Palladium‐Catalyzed Decarboxylative [4+2] Cycloadditions
Authors: Wei Yi , Lu Liang‐Qiu , Li Tian‐Ren , Feng Bin , Wang Qiang , Xiao Wen‐Jing , Alper Howard 
Published: January 2016

AbstractA new hybrid P,S ligand was exploited by combining a chiral β‐amino sulfide and a simple diphenyl phosphite. The resultant ligand performs extremely well in a palladium‐catalyzed asymmetric decarboxylative [4+2] cycloaddition reaction, thus generating multiple contiguous stereocenters and a chiral quaternary center. By doing so, a straightforward route to highly functionalized tetrahydroquinolines was developed with yields of up to 99 %, as well as 98 % ee and greater than 95:5 d.r. Moreover, mechanistic insights into this transformation and the possible stereocontrol are discussed.
Bioconjugating Thiols to Poly(acrylamide) Gels for Cell Culture Using Methylsulfonyl Co‐monomers
Authors: Farrukh Aleeza , Paez Julieta I. , Salierno Marcelo , del Campo Aránzazu 
Published: January 2016

AbstractPoly(acrylamide) P(AAm) gels have become relevant model substrates to study cell response to the mechanical and biochemical properties of the cellular microenvironment. However, current bioconjugation strategies to functionalize P(AAm) gels, mainly using photoinduced arylazide coupling, show poor specificity and hinder conclusive studies of material properties and cellular responses. We describe methylsulfonyl‐containing P(AAm) hydrogels for cell culture. These gels allow easy, specific and functional covalent coupling of thiol containing bioligands in tunable concentrations under physiological conditions, while retaining the same swelling, porosity, cytocompatibility, and low protein adsorption of P(AAm) gels. These materials allow quantitative and standardized studies of cell‐materials interactions with P(AAm) gels.
Synthesis, Separation, and Characterization of Small and Highly Fluorescent Nitrogen‐Doped Carbon NanoDots
Authors: Arcudi Francesca , Đorđević Luka , Prato Maurizio 
Published: January 2016

AbstractA facile bottom‐up approach to carbon nanodots (CNDs) is reported, using a microwave‐assisted procedure under controlled conditions. The as‐prepared nitrogen‐doped CNDs (NCNDs) show narrow size‐distribution, abundant surface traps and functional groups, resulting in tunable fluorescent emission and excellent solubility in water. Moreover, we present a general method for the separation of NCNDs by low‐pressure size‐exclusion chromatography, leading to an even narrower size distribution, different surface composition, and optical properties. They display among the smallest size and the highest FLQYs reported so far. 13C‐enriched starting materials produced N13CNDs suitable for thorough NMR studies, which gave useful information on their molecular structure. Moreover, they can be easily functionalized and can be used as water‐soluble carriers. This work provides an avenue to size‐ and surface‐controllable and structurally defined NCNDs for applications in areas such as optoelectronics, biomedicine, and bioimaging.
Inverted Wedding Cake Growth Operated by the Ehrlich–Schwoebel Barrier in Two‐Dimensional Nanocrystal Evolution
Authors: Yin Xin , Geng Dalong , Wang Xudong 
Published: January 2016

AbstractWedding cake growth is a layer‐by‐layer growth model commonly observed in epitaxial growth of metal films, featured by repeated nucleation of new atomic layers on the topmost surface owing to the confinement of the Ehrlich–Schwoebel (ES) barrier. Herein, we report an inverted wedding cake growth phenomenon observed in two‐dimensional nanostructure evolution. Through a dynamically controlled vapor–solid deposition process of ZnO, a unique basin‐shaped crown was formed on the tip of each nanowire, featured with concentric steps. The atomic steps were nucleated along the edge and propagated toward the center. This is an opposite growth behavior compared to the conventional wedding cake growth, and is thus denoted as inverted wedding cake growth. Through the relation between the crown expansion rate and the temperature, the ES barrier of ZnO was determined to be 0.88 eV. The discovery of inverted wedding cake growth provided insight into the developing nanostructure growth mechanisms.
Electrocatalytic Generation of Amidyl Radicals for Olefin Hydroamidation: Use of Solvent Effects to Enable Anilide Oxidation
Authors: Zhu Lin , Xiong Peng , Mao Zhong‐Yi , Wang Yong‐Heng , Yan Xiaomei , Lu Xin , Xu Hai‐Chao 
Published: January 2016

AbstractOxidative generation of synthetically important amidyl radicals from N−H amides is an appealing and yet challenging task. Previous methods require a stoichiometric amount of a strong oxidant and/or a costly noble‐metal catalyst. We report herein the first electrocatalytic method that employs ferrocene (Fc), a cheap organometallic reagent, as the redox catalyst to produce amidyl radicals from N‐aryl amides. Based on this radical‐generating method, an efficient intramolecular olefin hydroamidation reaction has been developed.
Importance of Intermolecular Hydrogen Bonding for the Stereochemical Control of Allene–Enone (3+2) Annulations Catalyzed by a Bifunctional, Amino Acid Derived Phosphine Catalyst
Authors: Holland Mareike C. , Gilmour Ryan , Houk K. N. 
Published: January 2016

AbstractThe origin of stereoselectivity in the (3+2) annulation of allenes and enones catalyzed by an amino acid derived phosphine catalyst has been investigated by the use of dispersion‐corrected density functional theory. An intermolecular hydrogen bond between the intermediate zwitterion and the enone was found to be the key interaction in the two enantiomeric transition states. Additional stabilization is provided by intermolecular hydrogen‐bonding interactions between acidic positions on the catalyst backbone and the substrate. Enantioselectivity occurs because the intermolecular hydrogen bond in the transition state leading to the minor enantiomer is only possible at the expense of reactant distortion.
Oriented Chiral DNA–Silica Film Guided by a Natural Mica Substrate
Authors: Cao Yuanyuan , Kao Kunche , Mou Chungyuan , Han Lu , Che Shunai 
Published: January 2016

AbstractThe formation of highly ordered chiral organic/inorganic films with high density and long‐range orientation is important in constructing chiral devices, such as broadband polarization devices, liquid‐crystal displays, or negative‐reflection materials. A feasible strategy is presented to fabricate three‐dimensional mesostructured chiral DNA–silica assemblies into large‐scale oriented arrangements. The highly ordered film was aligned by a mica crystal substrate with the bridging effect of suitable divalent metal ions, followed by the growth of the DNA–silica composite by bottom‐up assembly with a “quartet templating” method. This simple and effective route would perform well in the alignment and arrangement of highly charged biomolecules, such as polypeptides, proteins, viruses, and their inorganic assemblies, and furthermore could allow the fabrication of chiral optical materials with long‐range ordering.
Direct Detection of Supramolecular Reaction Centers in the Methanol‐to‐Olefins Conversion over Zeolite H‐ZSM‐5 by 13C–27Al Solid‐State NMR Spectroscopy
Authors: Wang Chao , Wang Qiang , Xu Jun , Qi Guodong , Gao Pan , Wang Weiyu , Zou Yunyun , Feng Ningdong , Liu Xiaolong , Deng Feng 
Published: January 2016

AbstractHydrocarbon‐pool chemistry is important in methanol to olefins (MTO) conversion on acidic zeolite catalysts. The hydrocarbon‐pool (HP) species, such as methylbenzenes and cyclic carbocations, confined in zeolite channels during the reaction are essential in determining the reaction pathway. Herein, we experimentally demonstrate the formation of supramolecular reaction centers composed of organic hydrocarbon species and the inorganic zeolite framework in H‐ZSM‐5 zeolite by advanced 13C–27Al double‐resonance solid‐state NMR spectroscopy. Methylbenzenes and cyclic carbocations located near Brønsted acid/base sites form the supramolecular reaction centers in the zeolite channel. The internuclear spatial interaction/proximity between the 13C nuclei (associated with HP species) and the 27Al nuclei (associated with Brønsted acid/base sites) determines the reactivity of the HP species. The closer the HP species are to the zeolite framework Al, the higher their reactivity in the MTO reaction.
Numerical study on the performance of an adapted radiant syngas cooler with water spray for entrained‐flow gasifier
Authors: Li Xianbin , Guo Qinghua , Qiu Shouxian , Yu Guangsuo 
Published: January 2016

AbstractAn adapted radiant syngas cooler (RSC) with water spray for entrained‐flow gasifier has been technically reformed to achieve higher reliability and availability of coal‐gasification‐based system. The multiphase flow, heat transfer and mass transfer processes in this adapted RSC have been studied by a developed 3D computational fluid dynamics model. A Eulerian–Lagrangian method is adopted to describe the flow behavior of the syngas, slag/ash particle and water droplets. The surface temperature of water wall Ta is calculated using heat flux balance equations by compiling user‐defined functions. The predicted values agree well with the measured ones obtained from a practical gasification plant. In the inner cylinder, syngas temperature contours are similar to circulars dispersed from center to the division walls and have a high gradient near water walls, especially close to the division walls. The gradient of Ta from center to division walls is similar to that of gas temperature. This adapted RSC with water spray has a better flexibility, while the flow rate of water spray can be adjusted for different operating conditions of gasifier. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
“The Road to the Village”: Israeli Social Unconscious and the Palestinian Nakba
Authors: Even‐Tzur Efrat 
Published: January 2016

AbstractThis paper tackles the paradox inherent in Israeli attempts to silence the Palestinian Nakba: despite massive effacement efforts, the traces of the Nakba remain all‐pervasive in Israeli culture and collective memory. Several silencing practices are described and discussed from a Freudian perspective, as instances of collective repression of anxiety provoking material. Furthermore, it is suggested that as far as the Nakba is concerned, this repression might be the result of collective perpetrator trauma. Finally, the paper offers several intriguing examples of “social traumatic symptoms”, which are understood as signs of the return of the repressed. According to LaCapra, collective post‐traumatic symptoms serve as obstacles to the formation of just and responsible societies. Thus, the paper concludes with a discussion of the socially therapeutic value of the current analysis and its potential contribution to long term processes of collective working through and decolonization. Copyright © 2016 John Wiley & Sons, Ltd.
Spatial differences across the French Pyrenees in the use of local habitat by the endangered semi‐aquatic Pyrenean desman (Galemys pyrenaicus)
Authors: Biffi Marjorie , Charbonnel Anaïs , Buisson Laëtitia , Blanc Frédéric , Némoz Mélanie , Laffaille Pascal 
Published: January 2016

Abstract

The implementation of effective and appropriate protection actions is frequently hindered by lack of thorough knowledge on species ecology especially in the case of endemic, vulnerable and elusive species.
Using a recently updated and unpublished dataset describing the spatial distribution of the Pyrenean desman (Galemys pyrenaicus) in its northern range (French Pyrenees), an Ecological Niche Factor Analysis (ENFA) was conducted to provide a quantitative estimate of local habitat use by this endangered semi‐aquatic mammal. A comparative approach was used to investigate potential differences in habitat use among the three main hydrological regions of the French Pyrenees.
The Pyrenean desman was identified as a marginal and specialist species concerning the selection of its local habitat in the French Pyrenees. Key habitat variables corresponded mainly to river‐bed characteristics (i.e. high heterogeneity of shelters and river substrates, fast flowing water facies, low amounts of fine sediment) and river‐bank characteristics (i.e. high proportion of rocks, low proportion of earth). A difference in habitat selection between the three hydrological regions of the French Pyrenees was also highlighted. A decrease in marginality and specialization from west to east as well as differences in habitat variables driving the ecological niche of the Pyrenean desman and its range suggested a spatial structure in desman populations regarding local ecological factors.
These results stress the importance of effective and sustainable river management for the habitat quality of this endangered species and also demonstrate the importance of taking into account the variability in habitat preferences that can exist between geographically distinct populations. This finding has important implications for conservation planning that should thus be conducted at the population level instead of the traditional species level in order to target the specific needs of each hydrological region.
Copyright © 2016 John Wiley & Sons, Ltd.
ω‐Imidazolyl‐ and ω‐Tetrazolylalkylcarbamates as Inhibitors of Fatty Acid Amide Hydrolase: Biological Activity and in vitro Metabolic Stability
Authors: Terwege Tobias , Hanekamp Walburga , Garzinsky David , König Simone , Koch Oliver , Lehr Matthias 
Published: January 2016

AbstractFatty acid amide hydrolase (FAAH) is a serine hydrolase that terminates the analgesic and anti‐inflammatory effects of endocannabinoids such as anandamide. Herein, structure–activity relationship studies on a new series of aryl N‐(ω‐imidazolyl‐ and ω‐tetrazolylalkyl)carbamate inhibitors of FAAH were investigated. As one result, a pronounced increase in inhibitory potency was observed if a phenyl residue attached to the carbamate oxygen atom was replaced by a pyridin‐3‐yl moiety. The most active compounds exhibited IC50 values in the low nanomolar range. In addition, investigations on the metabolic properties of these inhibitors were performed. In rat liver homogenate and in porcine plasma, the extent of their degradation was shown to be strongly dependent on the kind of aryl residue bound to the carbamate as well as on the length and type of the alkyl spacer connecting the carbamate group with the heterocyclic system. With the aid of esterase inhibitors it was shown that in porcine plasma, carboxylesterase‐like enzymes and paraoxonase are involved in carbamate cleavage. Moreover, it was found that highly active pyridin‐3‐yl carbamates reacted with albumin, which led to covalent albumin adducts.
Interpolation, extrapolation, and truncation in computations of CIE tristimulus values
Authors: Wang Zhifeng , Zhao Binghao , Li Jiqiang , Luo Ming Ronnier , Pointer Michael R. , Melgosa Manuel , Li Changjun 
Published: January 2016

AbstractThis article addresses some general practices for the computation of CIE tristimulus values (TSVs), including different methods used for the interpolation, extrapolation, and truncation of data in the visible wavelength range. In each case, a quantitative analysis is presented on the basis of a dataset with 2365 spectral reflectances covering a wide color gamut, assuming six CIE illuminants and the two CIE standard colorimetric observers. For interpolation, it is found that among five tested methods, the (cubic) spline method is the best one when the spectral reflectance factors are uniformly sampled over the visible wavelength range. For extrapolation, it is found that the second‐order extrapolation method gives better results than the use of nearest available data points or linear extrapolation methods. With respect to truncation, considering five different usual truncated ranges, it is found that the range from 360 to 780 nm provides more accurate results than the range from 380 to 780 nm currently recommended by CIE for nonfluorescent samples, and the use of the truncated range from 400 to 700 nm in place of the CIE‐recommended range of 360 to 830 nm leads to TSVs with considerably high color differences of up to 0.9 CIELAB units. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 10–18, 2017
Electropolymerization of Uniform Polyaniline Nanorod Arrays on Conducting Oxides as Counter Electrodes in Dye‐Sensitized Solar Cells
Authors: He Ziming , Liu Jing , Khoo Si Yun , Tan Timothy Thatt Yang 
Published: January 2016

AbstractConventional techniques for the synthesis of oriented polyaniline (PANI) nanostructures are often complex or time consuming. Through an innovative reduced graphene oxide (rGO) modified FTO and a low‐potential electropolymerization strategy, the rapid and template‐free growth of a highly ordered PANI nanorod array on the FTO substrate is realized. The highly ordered nanostructure of the PANI array leads to a high electrocatalytic activity and chemical stability. The importance of the polymerization potential and rGO surface modification to achieve this nanostructure is revealed. Compared to platinum, the PANI nanorod array exhibits an enhanced performance and stability as counter electrodes in dye‐sensitized solar cells, with a 17.6 % enhancement in power conversion efficiency.
Phase noise analysis in CMOS differential Armstrong oscillator topology
Authors: Chlis Ilias , Pepe Domenico , Zito Domenico 
Published: January 2016

SummaryThis paper reports a phase noise analysis in a differential Armstrong oscillator circuit topology in CMOS technology. The analytical expressions of phase noise due to flicker and thermal noise sources are derived and validated by the results obtained through SpectreRF simulations for oscillation frequencies of 1, 10, and 100 GHz. The analysis captures well the phase noise of the oscillator topology and shows the impact of flicker noise contribution as the major effect leading to phase noise degradation in nano‐scale CMOS LC oscillators. Copyright © 2016 John Wiley & Sons, Ltd.
Electrospray mass spectrometry as a tool to characterize phospholipid composition of plant cakes
Authors: Buré Corinne , Solgadi Audrey , Yen‐Nicolaÿ Stéphanie , Bardeau Tiphaine , Libong Danielle , Abreu Sonia , Chaminade Pierre , Subra‐Paternault Pascale , Cansell Maud 
Published: January 2016

Phospholipids (PL) are components of increased value in nutritional applications, especially those rich in polyunsaturated fatty acids (PUFA) such as α‐linolenic acid (ALA, 18:3 n‐3) and linoleic acid (LA, 18:2 n‐6). Currently, the oil processing industry generates by‐products in the form of oilseed and plant cakes that can be valorized for food/feed applications. With the aim of diversifying PL sources and improving their identification in terms of fatty acid (FA) composition, plant cakes obtained from five different sources (camelina, flaxseed, hemp, sesame, walnut) were extracted and analyzed by lipidomics approach using three analytical methods of mass spectrometry (MS): (i) shotgun; (ii) reverse phase liquid chromatography (RPLC) in multiple reaction monitoring (MRM) mode; and (iii) normal phase liquid chromatography (NPLC) with data dependant scan MS fragmentation. We obtained complementary information: while shotgun allowed identifying PL species, RPLC associated to MRM enabled to access high sensitivity and to focus on minority species. Then, NPLC in data dependant scan led to the identification of lysophospholipids and cardiolipin species besides phosphatidylcholine (PC). Among, the five plant cakes analyzed, camelina cake showed the highest percentage of ALA. If ALA was also found in flaxseed and hemp cakes, it was in a lesser extent. Moreover, ALA was located on the sn‐2 position of the glycerol backbone, a valuable position for nutritional applications.Practical applications: The food industry generates large amounts of by‐products, and most of them remain unused. Among them, degumming pastes, i.e., by‐products from the oil refining process, could be valuable sources of phospholipids (PL). These phospholipids present interesting properties, as emulsifiers, thickening agents, or antioxidants, for food or cosmetic industries. Moreover, depending on the plant source, the fatty acid composition in phospholipids could be different from that of the oil (mainly composed of triglycerides instead of phospholipids), especially for α‐linolenic acid (ALA, 18:3 n‐3). Among, the five plant cakes analyzed (camelina, flaxseed, hemp, sesame, walnut), camelina cake showed the highest percentage of ALA. If ALA was also found in flaxseed and hemp cakes, it was in a lesser extent. Moreover, ALA was located in the sn‐2 position of the glycerol, a valuable position for nutritional applications. On the whole, using powerful and complementary analytical procedures for PL characterization allowed widening the potential sources of this type of lipids.Workflow of the plant cake lipid analysis based on three analytical methods of mass spectrometry.
Partial characterization of jumbo squid skin pigment extract and its antioxidant potential in a marine oil system
Authors: Aubourg Santiago P. , Torres‐Arreola Wilfrido , Trigo Marcos , Ezquerra‐Brauer Josafat Marina 
Published: January 2016

Pigment compounds were extracted from jumbo squid (Dosidicus gigas) skin with an acid‐ethanol solvent (JSE). Freeze‐dried JSE was characterized with respect to solubility in different solvents, absorption UV–VIS, and FT‐IR spectra, and tested for its radical scavenging activity against ABTS and oxygen radical absorbance capacity (ORAC). The potential ability of JSE for inhibiting oxidation of cod liver oil (CLO) was also determined by monitoring dienes, trienes, peroxide value (PV), thiobarbutiric acid (TBA), and polyene index (PI) in samples stored at 15, 25, and 50°C for 12 days. Concentrations of 0, 0.1, 0.5, 1, and 2% JSE were added to CLO. The yield of JSE was 8.8 mg/g freeze‐dried skin. Solubility behavior, UV–Vis, and FT‐IR spectra of JSE suggests that this pigment extract might belong to the ommochrome family. Moreover, a characteristic xanthommatin peak (1740 cm−1) was observed. JSE exhibited scavenging activity on ABTS•+ radical and in the ORAC assay. After storage PV and TBA increased, whereas PI decreased mainly in the control treatment. The addition of JSE delayed lipid oxidation in CLO during the first 8 days of storage at 50°C. JSE was identified as promising source of antioxidants to retard fish lipid oxidation.Practical applications: This study demonstrates that acid‐ethanol pigment extract from jumbo squid skin, which is a by‐product generated by the squid processing industries, is a valuable antioxidant source. Consistent with the preservative effect observed for this pigment extract, squid skin may be successfully employed to obtain new products for food processing and the pharmaceutical industry, with environmental sustainability benefits and provide a more effective use for jumbo squid by‐products.Acid‐ethanol pigment extracts from freeze‐dried jumbo squid skin (JSE) were added to cod liver oil and stored at 50°C. Increasing levels of JSE (0 < 0.1 < 0.5 < 1 < 2%) led to less lipid oxidation. JSE likely belongs to the ommochromes family.