bluuebunny/crossref_metadata_2025_split huggingface dataset:
MALDIMass Spectrometry Imaging of Biological Structures
Authors: Zaima Nobuhiro , Goto‐Inoue Naoko , Hayasaka Takahiro 
Published: September 2015

AbstractMatrix‐assisted laser desorption/ionization (MALDI) is a ‘soft’ ionization method which enables the detection of several molecules including proteins, peptides, amino acids, sugars, lipids, and metabolites, in biological samples. The versatility of MALDI makes it essential analytical method to detect the molecules of interest in the complex biological structures. To take this advantage of MALDI, matrix‐assisted laser desorption/ionization mass spectrometry imaging (MALDI‐MSI) has been developed as a molecular imaging method to visualize the spatial distribution of molecules in biological sample section. It has been reported that almost all kinds of molecules, such as biomolecules and administrated drugs or food factors, in biological samples can be visualized by MALDI‐MSI. Because many of these molecules cannot be visualized with the exception of MALDI‐MSI, MALDI‐MSI opens a new frontier in several fields such as medical science, pharmaceutical science, plant science, and food science. To obtain biologically meaningful information of the distribution of molecules of interest, researcher should understand the basic experimental steps and potential applications of MALDI‐MSI. In this article, principle, basic experimental procedure, and applications of MALDI‐MSI are described.
Application of Second Harmonic Imaging Microscopy in Biological Studies
Authors: Tjin Gavin , Cox Guy 
Published: September 2015

Abstract
The fact that some crystalline substances can generate the second harmonic (SH) – light of twice the frequency – under intense irradiation was discovered soon after lasers were available. Later, it was realized that some biological polymers were also able to generate the SH, offering a label‐free way of imaging cell components in the microscope. To obtain sufficiently intense light without damaging the sample, pulsed lasers are needed, typically delivering 100 fs pulses at ∼10 ns intervals. The signal is only generated at the focus of the beam so the image is inherently focal‐plane selective. Molecules that generate the SH must have no center of symmetry, and the signal is greatly enhanced if they are crystalline. Collagen has been the most studied biopolymer, and its structure and arrangement is a wide range of normal and diseased tissues has been investigated. The proteins myosin and tubulin have also been much studied. The polysaccharides starch and cellulose also give an SH signal, but to date they have received less attention. As second harmonic generation (SHG) is an electric field effect, changes in the field around a molecule will affect the signal, and this has been used to devise fast‐responding reporter dyes to measure membrane potential at high resolution.
Synthesis of Benzimidazole‐Substituted Arylboronic Acids via Aerobic Oxidation of 1,2‐Arylenediamines and Formyl‐Substituted Aryl MIDA Boronates using Potassium Iodide as a Catalyst
Authors: Lee Ye‐Sol , Cheon Cheol‐Hong 
Published: September 2015

AbstractA highly efficient protocol for the synthesis of benzimidazole‐substituted arylboronic acids was developed via aerobic oxidative cyclization of 1,2‐aryldiamines and formyl‐substituted aryl MIDA (N‐methyliminodiacetic acid) boronates using potassium iodide as a nucleophilic catalyst. Furthermore, a one‐pot protocol for the synthesis of benzimidazole‐substituted arylboronic acids from 1,2‐phenylenediamines and formyl‐substituted arylboronic acids was developed without the isolation of any intermediates. The resulting boronic acids were further subjected to Suzuki–Miyaura coupling reactions without isolation, leading to diaryl‐substituted benzimidazoles with only one separation step.magnified image
Palladium‐Catalysed CH Bond Electrophilic Fluorination of Highly Substituted Arylpyrazoles: Experimental and DFT Mechanistic Insights
Authors: Testa Christelle , Roger Julien , Scheib Stephanie , Fleurat‐Lessard Paul , Hierso Jean‐Cyrille 
Published: September 2015

AbstractA general protocol for palladium‐catalysed CH mono‐ and di‐fluorination of highly substituted arylpyrazoles is reported. Coupling pathways and substrate limitations are discussed in the light of complementary mechanistic experimental and density functional theory (DFT) studies. The mono‐ and di‐ortho‐fluorination of arylpyrazoles having substituted pyrazole groups and ortho‐, meta‐, or para‐substituted arene moieties is achieved. Various pyrazole groups can efficiently promote the direct CH activation/fluorination of substrates bearing valuable reactive ester, cyano, halide and nitro functions. The presence of methoxy, methyl and trifluoromethyl is tolerated on the pyrazole directing groups. However, steric substituent effects have a marked influence which is evidenced by calculations. DFT modelling suggested also a previously unseen outer‐sphere oxidative addition of N‐fluorobenzenesulfonimide (NFSI) to Pd(II) as an alternative mechanism to the commonly assumed Pd(II)/Pd(IV) process. This unprecedented proposal, which is supported by the mass spectrometry identification of a key Pd(II) monomer under the stoichiometric conditions deserves more attention. The influence of elaborate highly substituted directing groups on the course of Pd‐catalysed fluorination has generally received limited attention although this question has a crucial synthetic utility; herein, appropriate conditions for isolating pure products are reported.magnified image
Ring‐Opening of N‐tert‐Butanesulfinylethynylaziridines with Lithium Tris(dimethylphenylsilyl)zincate: Stereoselective Access to 4‐Amino‐1‐allenylsilanes
Authors: Bochatay Valentin N. , Sanogo Youssouf , Chemla Fabrice , Ferreira Franck , Jackowski Olivier , Pérez‐Luna Alejandro 
Published: September 2015

AbstractThe ring‐opening of N‐tert‐butanesulfinylethynylaziridines with lithium tris(dimethylphenylsilyl)zincate is reported. The reaction is demonstrated to be both stereoselective and stereospecific and to proceed through an anti‐SN2′ process. Further deprotection of the nitrogen atom under mild conditions allows access to 4‐amino‐1‐(dimethylphenylsilyl)allenes with high yields and levels of stereoselectivity.magnified image
A One‐Pot Approach to Phenanthridine Derivatives through Two‐Step Rhodium(I) and Gold(I) Catalysis
Authors: Zhu Zizhong , Chen Kai , Xu Qin , Shi Min 
Published: September 2015

AbstractAn effective one‐pot procedure for the synthesis of phenanthridine derivatives containing N‐ or O‐heterocycles has been developed through a two‐step rhodium‐catalyzed [2+2+2] cycloaddition and gold‐catalyzed heterocyclization under mild conditions. The substrate scope has been investigated and a plausible reaction mechanism has been proposed on the basis of control experiments and previous literature reports.magnified image
Copper‐Catalyzed Cascade Cyclization for the Synthesis of Trifluoromethyl‐Substituted Spiro‐2H‐azirines from 1,6‐Enynes
Authors: He Yu‐Tao , Wang Qiang , Zhao Jiahui , Wang Xiao‐Zhen , Qiu Yi‐Feng , Yang Yu‐Chen , Hu Jing‐Yuan , Liu Xue‐Yuan , Liang Yong‐Min 
Published: September 2015

AbstractA method for the synthesis of trifluoromethyl CF3‐substituted spirocyclic compounds containing with a unique quaternary carbon center from readily available starting materials has been developed. The reaction provides a facile access to 2H‐azirines via cascade cyclization. These compounds constitute a new class of functionalized synthetic intermediates, which can be used for the synthesis of various nitrogen‐containing heterocycles and biologically active CF3‐containing compounds.magnified image
Locating Gases in Porous Materials: Cryogenic Loading of Fuel‐Related Gases Into a Sc‐based Metal–Organic Framework under Extreme Pressures
Authors: Sotelo Jorge , Woodall Christopher H. , Allan Dave R. , Gregoryanz Eugene , Howie Ross T. , Kamenev Konstantin V. , Probert Michael R. , Wright Paul A. , Moggach Stephen A. 
Published: September 2015

AbstractAn alternative approach to loading metal organic frameworks with gas molecules at high (kbar) pressures is reported. The technique, which uses liquefied gases as pressure transmitting media within a diamond anvil cell along with a single‐crystal of a porous metal–organic framework, is demonstrated to have considerable advantages over other gas‐loading methods when investigating host–guest interactions. Specifically, loading the metal–organic framework Sc2BDC3with liquefied CO2at 2 kbar reveals the presence of three adsorption sites, one previously unreported, and resolves previous inconsistencies between structural data and adsorption isotherms. A further study with supercritical CH4at 3–25 kbar demonstrates hyperfilling of the Sc2BDC3and two high‐pressure displacive and reversible phase transitions are induced as the filled MOF adapts to reduce the volume of the system.
Exclusive π Encapsulation of Light Alkali Metal Cations by a Neutral Molecule
Authors: Bertermann Rüdiger , Braunschweig Holger , Constantinidis Philipp , Dellermann Theresa , Dewhurst Rian D. , Ewing William C. , Fischer Ingo , Kramer Thomas , Mies Jan , Phukan Ashwini K. , Vargas Alfredo 
Published: September 2015

AbstractCation–π interactions are one of the most important classes of noncovalent bonding, and are seen throughout biology, chemistry, and materials science. However, in almost every documented case, these interactions play only a supporting role to much stronger covalent or dative bonds, thus making examples of exclusive cation–π bonding exceedingly rare. In this study, a neutral diboryne molecule is found to encapsulate the light alkali metal cations Li+ and Na+ in the absence of a net charge, covalent bonds, or lone‐pair donor groups. The resulting encapsulation complexes are, to our knowledge, the first structurally authenticated species in which a neutral molecule binds the light alkali metals exclusively through cation–π interactions.
Organic–inorganic composite materials as photoinitiator for controlling/living polymerization
Authors: Liang En Xiang , Lu Mang , Hou Zhao Hui , Huang Yan , He Bin Hong , Wang Guo Xiang , Liu Li Chao , Wu Hu , Zhong Ming 
Published: September 2015

ABSTRACTTitanium dioxide (TiO2)/graphitic carbon nitride (g‐C3N4) composites were first used as photoinitiator for photochemically mediated controlled/living polymerization of methyl methacrylate. The polymerization was successfully carried out in polyethylene glycol at room temperature with FeCl3·6H2O/N,N,N ′,N ′,N ″‐pentamethyldiethylenetriamine as complex catalyst and ethyl 2‐bromoisobutyrate as initiator in this case. A pseudo‐first‐order dependence of the monomer concentration on the polymerization time was observed. TiO2/g‐C3N4 was verified to be an efficient photoinitiator. The polymerization was controlled to produce poly(methyl methacrylate) with narrow molecular weight distribution and controlled number average molecular weight (Mn,GPC). The Mn,GPC matched well with the theoretical values when using both UV and sunlight irradiation as light source. The effects of reaction conditions on the polymerization were investigated. The polymerization could be started and stopped through periodically switching on/off the light. The living nature was further supported by the chain extension experiments. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42891.
The Peptidome of Behçet's Disease–Associated HLA–B*51:01 Includes Two Subpeptidomes Differentially Shaped by Endoplasmic Reticulum Aminopeptidase 1
Authors: Guasp Pablo , Alvarez‐Navarro Carlos , Gomez‐Molina Patricia , Martín‐Esteban Adrian , Marcilla Miguel , Barnea Eilon , Admon Arie , López de Castro José A. 
Published: September 2015

ObjectiveTo characterize the peptidome of the Behçet's disease–associated HLA–B*51:01 allotype as well as the differential features of major peptide subsets and their distinct endoplasmic reticulum aminopeptidase 1 (ERAP‐1)–mediated processing.MethodsThe endogenous B*51:01‐bound peptidome was characterized from 721.221 transfectant cells, after affinity chromatography and acid extraction, by tandem mass spectrometry. Recombinant ERAP‐1 variants were used to digest synthetic B*51:01 ligands. HLA and transporter associated with antigen processing (TAP) binding affinities of peptide ligands were calculated with well‐established algorithms. ERAP‐1 and ERAP‐2 from 721.221 cells were characterized by genomic sequencing and Western blotting.ResultsThe B*51:01 peptidome consisted of 29.5% octamers, 61.7% nonamers, 4.8% decamers, and 4.0% longer peptides. The major peptide motif consisted of Pro and Ala at position 2, aliphatic/aromatic position 3 residues, and Val and Ile at the C‐terminal position. The ligands with Pro or Ala at position 2 constituted 2 distinct subpeptidomes. Peptides with Pro at position 2 showed higher affinity for B*51:01 and lower affinity for TAP than those with Ala at position 2. Most important, both peptide subsets differed drastically in the susceptibility of their position 1 residues to ERAP‐1, revealing a distinct influence of this enzyme on both subpeptidomes, which may alter their balance, affecting the global affinity of B*51:01–peptide complexes.Conclusion ERAP‐1 has a significant influence on the B*51:01 peptidome and its affinity. This influence is based on very distinct effects on the 2 subpeptidomes, whereby only peptides in the subpeptidome with Ala at position 2 are extensively destroyed, except when their position 1 residues are ERAP‐1 resistant. This pattern provides a mechanism for the epistatic association of ERAP‐1 and B*51:01 in Behçet's disease.
Constraining the orbits of small solar system bodies using spectroscopic Doppler shift measurements – a preliminary study
Authors: Zucker S. , Tzur I. 
Published: September 2015

AbstractIn this short paper we examine whether the measurement of Doppler shifts in the solar light reflected off an asteroid surface may improve the accuracy of the determined orbit. Our results suggest it will be worthwhile to use high‐resolution spectrographs, of the exoplanet‐hunting type, to measure those Doppler shifts. Spectroscopic Doppler shifts might improve the accuracy of Earth‐impact predictions, help to recover “lost” near‐Earth objects, and may also significantly enhance the knowledge about dynamics of the Kuiper belt. Future high‐resolution spectrographs on the VLT and the E‐ELT may thus have an important role in studies of Solar‐System dynamics and kinematics. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The isolated dSph galaxy KKs3 in the local Hubble flow
Authors: Karachentsev I. D. , Kniazev A. Yu. , Sharina M. E. 
Published: September 2015

AbstractWe present SALT spectroscopy of a globular cluster in the center of the nearby isolated dSph galaxy KKs3 situated at a distance of 2.12 Mpc. Its heliocentric radial velocity is 316 ± 7 km s–1 that corresponds to VLG = 112 km s–1 in the Local Group (LG) reference frame. We use its distance and velocity along with the data on other 35 field galaxies in the proximity of the LG to trace the local Hubble flow. The following basic properties of the local field galaxies are briefly discusse: morphology, absolute magnitudes, average surface brightnesses, specific star formation rates, and hydrogen mass‐to‐stellar mass ratios. Surprisingly, the sample of the neighboring isolated galaxies displays no signs of compression under the influence of the expanding Local Void. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kuwanon‐L as a New Allosteric HIV‐1 Integrase Inhibitor: Molecular Modeling and Biological Evaluation
Authors: Esposito Francesca , Tintori Cristina , Martini Riccardo , Christ Frauke , Debyser Zeger , Ferrarese Roberto , Cabiddu Gianluigi , Corona Angela , Ceresola Elisa Rita , Calcaterra Andrea , Iovine Valentina , Botta Bruno , Clementi Massimo , Canducci Filippo , Botta Maurizio , Tramontano Enzo 
Published: September 2015

AbstractHIV‐1 integrase (IN) active site inhibitors are the latest class of drugs approved for HIV treatment. The selection of IN strand‐transfer drug‐resistant HIV strains in patients supports the development of new agents that are active as allosteric IN inhibitors. Here, a docking‐based virtual screening has been applied to a small library of natural ligands to identify new allosteric IN inhibitors that target the sucrose binding pocket. From theoretical studies, kuwanon‐L emerged as the most promising binder and was thus selected for biological studies. Biochemical studies showed that kuwanon‐L is able to inhibit the HIV‐1 IN catalytic activity in the absence and in the presence of LEDGF/p75 protein, the IN dimerization, and the IN/LEDGF binding. Kuwanon‐L also inhibited HIV‐1 replication in cell cultures. Overall, docking and biochemical results suggest that kuwanon‐L binds to an allosteric binding pocket and can be considered an attractive lead for the development of new allosteric IN antiviral agents.
Synthesis of Platinum Catalysts over Thick Slurries of Oxide Supports by Strong Electrostatic Adsorption
Authors: Samad Jadid E. , Hoenig Sean , Regalbuto John R. 
Published: September 2015

AbstractPlatinum uptake by strong electrostatic adsorption on alumina, silica, and titania supports was studied at different slurry thicknesses (or surface loadings). For the anionic platinum chloride precursor, a high counterion concentration at high surface loadings hindered adsorption on the high point of zero charge alumina support, as predicted by the revised physical adsorption model. Owing to this adsorption retardation in thicker slurries, a highly dispersed Pt/Al2O3 catalyst could only be prepared with a lower weight fraction of Pt than that in thin slurries. However, for cationic platinum tetraamine complexes, the effect of counterions in retarding the adsorption at high surface loadings was unexpectedly diminished. As a result, it was possible to synthesize highly dispersed Pt/SiO2 even at a maximum slurry thickness (incipient wetness) without having to sacrifice the Pt loading.
Optimization of Experimental Parameters to Explore Small‐Ligand/Aptamer Interactions through Use of 1H NMR Spectroscopy and Molecular Modeling
Authors: Souard Florence , Perrier Sandrine , Noël Vincent , Fave Claire , Fiore Emmanuelle , Peyrin Eric , Garcia Julian , Vanhaverbeke Cécile 
Published: September 2015

AbstractAptamers constitute an emerging class of molecules designed and selected to recognize any given target that ranges from small compounds to large biomolecules, and even cells. However, the underlying physicochemical principles that govern the ligand‐binding process still have to be clarified. A major issue when dealing with short oligonucleotides is their intrinsic flexibility that renders their active conformation highly sensitive to experimental conditions. To overcome this problem and determine the best experimental parameters, an approach based on the design‐of‐experiments methodology has been developed. Here, the focus is on DNA aptamers that possess high specificity and affinity for small molecules, L‐tyrosinamide, and adenosine monophosphate. Factors such as buffer, pH value, ionic strength, Mg2+‐ion concentration, and ligand/aptamer ratio have been considered to find the optimal experimental conditions. It was then possible to gain new insight into the conformational features of the two ligands by using ligand‐observed NMR spectroscopic techniques and molecular mechanics.
Palladium‐Catalyzed Triple Cyclization of 2,7‐Alkadiynylic Carbonates with Allenes Bearing a Carbon Nucleophile
Authors: Huang Xin , Wu Wangteng , Fu Chunling , Yu Yihua , Ma Shengming 
Published: September 2015

AbstractPalladium‐catalyzed tandem reactions of 2,7‐alkadiynylic carbonates with allenes bearing a carbon nucleophile such as malonate and bis(phenylsulfonyl)methane for the efficient syntheses of fused tricycles, such as 3,5,6,7‐tetrahydro‐1H‐indeno[5,6‐c]furan, 1,2,3,5,6,7‐hexahydrocyclopenta[f]isoindole, and 1,2,3,5,6,7‐hexahydro‐s‐indacene derivatives, have been reported. The reaction forms two five‐membered rings and one benzene ring fusing them in the middle.
Manipulation of lipids in animal‐derived foods: Can it contribute to public health nutrition?
Authors: Givens D. Ian 
Published: September 2015

Foods derived from animals are an important source of nutrients for humans. Concerns have been raised that due to their SFA content, dairy foods may increase the risk of cardiometabolic disease. Prospective studies do not indicate an association between milk consumption and increased disease risk although there are less data for other dairy foods. SFA in dairy products can be partially replaced by cis‐MUFA through nutrition of the dairy cow although there are too few human studies to conclude that such modification leads to reduced chronic disease risk. Intakes of LCn‐3 FA are sub‐optimal in many countries and while foods such as poultry meat can be enriched by inclusion of fish oil in the diet of the birds, fish oil is expensive and has an associated risk that the meat will be oxidatively unstable. Novel sources of LCn‐3 FA such as krill oil, algae, and genetically modified plants may prove to be better candidates for meat enrichment. The value of FA‐modified foods cannot be judged by their FA composition alone and there needs to be detailed human intervention studies carried out before judgements concerning improved health value can be made.Practical applications: The amount and FA composition of dietary lipids are known to contribute to the risk of chronic disease in humans which is increasing and becoming very costly to treat. The use of animal nutrition to improve the FA composition of staple foods such as dairy products and poultry meat has considerable potential to reduce chronic risk at population level although judgements must not be based simply on FA composition of the foods.Foods from animals supply important nutrients to humans. Many also supply saturated fats, usually assumed to be bad for health (see Figure from [51]) although research shows the food that supplies them can alter their effect. In addition, the animals ‘diets can substantially alter the fatty acid composition of the food products and this may be an important means of improving diets in the future.