bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Enantioselective Total Synthesis of Exochomine
Authors: Gao Alison X. , Hamada Tomoaki , Snyder Scott A. 
Published: July 2016

AbstractMolecules that possess fully substituted chiral centers are often challenging to construct, particularly if those centers connect two seemingly different halves or include a nitrogen atom. Herein, we describe an efficient approach to a molecule that combines both challenges in a single center in the form of exochomine. Failures in direct coupling led to a design fueled by highly specific reaction conditions for several steps and the development of an improved protocol for 1,4‐reduction in a hindered context where numerous side reactions were possible. These chemoselective solutions should have value to other problems. Challenges in obtaining matching spectral data for the synthesized natural product are also discussed.
Controlled Gas Exfoliation of Boron Nitride into Few‐Layered Nanosheets
Authors: Zhu Wenshuai , Gao Xiang , Li Qian , Li Hongping , Chao Yanhong , Li Meijun , Mahurin Shannon M. , Li Huaming , Zhu Huiyuan , Dai Sheng 
Published: July 2016

AbstractThe controlled exfoliation of hexagonal boron nitride (h‐BN) into single‐ or few‐layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h‐BN. Here, we present an efficient strategy for the scalable synthesis of few‐layered h‐BN nanosheets (BNNS) using a novel gas exfoliation of bulk h‐BN in liquid N2 (L‐N2). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h‐BN and the cryogenic L‐N2 gasification to exfoliate the h‐BN. The produced BNNS after ten cycles (BNNS‐10) consisted primarily of fewer than five atomic layers with a high mass yield of 16–20 %. N2 sorption and desorption isotherms show that the BNNS‐10 exhibited a much higher specific surface area of 278 m2 g−1 than that of bulk BN (10 m2 g−1). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h‐BN. Subseqently, the L‐N2 penetrates into the interlayers of h‐BN along the curling edge, followed by an immediate drastic gasification of L‐N2, further peeling off h‐BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields.
Thin Heterojunctions and Spatially Separated Cocatalysts To Simultaneously Reduce Bulk and Surface Recombination in Photocatalysts
Authors: Li Ang , Chang Xiaoxia , Huang Zhiqi , Li Chengcheng , Wei Yijia , Zhang Lei , Wang Tuo , Gong Jinlong 
Published: July 2016

AbstractEfficient charge separation and light absorption are crucial for solar energy conversion over solid photocatalysts. This paper describes the construction of Pt@TiO2@In2O3@MnOx mesoporous hollow spheres (PTIM‐MSs) for highly efficient photocatalytic oxidation. TiO2–In2O3 double‐layered shells were selectively decorated with Pt nanoparticles and MnOx on the inner and outer surfaces, respectively. The spatially separated cocatalysts drive electrons and holes near the surface to flow in opposite directions, while the thin heterogeneous shell separates the charges generated in the bulk phase. The synergy between the thin heterojunctions and the spatially separated cocatalysts can simultaneously reduce bulk and surface/subsurface recombination. In2O3 also serves as a sensitizer to enhance light absorption. The PTIM‐MSs exhibit high photocatalytic activity for both water and alcohol oxidation.
Single‐Molecule Sensors: Challenges and Opportunities for Quantitative Analysis
Authors: Gooding J. Justin , Gaus Katharina 
Published: July 2016

AbstractMeasurement science has been converging to smaller and smaller samples, such that it is now possible to detect single molecules. This Review focuses on the next generation of analytical tools that combine single‐molecule detection with the ability to measure many single molecules simultaneously and/or process larger and more complex samples. Such single‐molecule sensors constitute a new type of quantitative analytical tool, as they perform analysis by molecular counting and thus potentially capture the heterogeneity of the sample. This Review outlines the advantages and potential of these new, quantitative single‐molecule sensors, the measurement challenges in making single‐molecule devices suitable for analysis, the inspiration biology provides for overcoming these challenges, and some of the solutions currently being explored.
Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio‐Inspired Materials for “Mineral Plastics”
Authors: Sun Shengtong , Mao Li‐Bo , Lei Zhouyue , Yu Shu‐Hong , Cölfen Helmut 
Published: July 2016

AbstractGiven increasing environmental issues due to the large usage of non‐biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio‐inspired synthesis of mineral‐based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)‐based hydrogel consisting of very small ACC nanoparticles physically cross‐linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self‐healable. Upon drying, the hydrogel forms free‐standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the “mineral plastics”.
Highly Tunable Selectivity for Syngas‐Derived Alkenes over Zinc and Sodium‐Modulated Fe5C2 Catalyst
Authors: Zhai Peng , Xu Cong , Gao Rui , Liu Xi , Li Mengzhu , Li Weizhen , Fu Xinpu , Jia Chunjiang , Xie Jinglin , Zhao Ming , Wang Xiaoping , Li Yong‐Wang , Zhang Qianwen , Wen Xiao‐Dong , Ma Ding 
Published: July 2016

AbstractZn‐ and Na‐modulated Fe catalysts were fabricated by a simple coprecipitation/washing method. Zn greatly changed the size of iron species, serving as the structural promoter, while the existence of Na on the surface of the Fe catalyst alters the electronic structure, making the catalyst very active for CO activation. Most importantly, the electronic structure of the catalyst surface suppresses the hydrogenation of double bonds and promotes desorption of products, which renders the catalyst unexpectedly reactive toward alkenes—especially C5+ alkenes (with more than 50% selectivity in hydrocarbons)—while lowering the selectivity for undesired products. This study enriches C1 chemistry and the design of highly selective new catalysts for high‐value chemicals.
Highly Efficient Synthesis of Multiantennary Bisected N‐glycans Based on Imidates
Authors: Mönnich Manuel , Eller Steffen , Karagiannis Theodoros , Perkams Lukas , Luber Thomas , Ott Dimitri , Niemietz Mathäus , Hoffman Joanna , Walcher Janika , Berger Lukas , Pischl Matthias , Weishaupt Markus , Wirkner Cathrin , Lichtenstein Rachel G. , Unverzagt Carlo 
Published: July 2016

AbstractThe occurrence of N‐glycans with a bisecting GlcNAc modification on glycoproteins has many implications in developmental and immune biology. However, these particular N‐glycans are difficult to obtain either from nature or through synthesis. We have developed a flexible and general method for synthesizing bisected N‐glycans of the complex type by employing modular TFAc‐protected donors for all antennae. The TFAc‐protected N‐glycans are suitable for the late introduction of a bisecting GlcNAc. This integrated strategy permits for the first time the use of a single approach for multiantennary N‐glycans as well as their bisected derivatives via imidates, with unprecedented yields even in a one‐pot double glycosylation. With this new method, rare N‐glycans of the bisected type can be obtained readily, thereby providing defined tools to decipher the biological roles of bisecting GlcNAc modifications.
Carbonylation of Difluoroalkyl Bromides Catalyzed by Palladium
Authors: Zhao Hai‐Yang , Feng Zhang , Luo Zhiji , Zhang Xingang 
Published: July 2016

AbstractAlthough important progress has been made in the fluoroalkylation reactions, the transition‐metal‐catalyzed carbonylative fluoroalkylation reaction remains challenging so far. Herein, we report the first example of a Pd‐catalyzed carbonylation of difluoroalkyl bromides with (hetero)arylboronic acids under one atmosphere pressure of CO. The reaction can also be extended to the aryl potassium trifluoroborate salts. The advantages of this protocol are synthetic simplicity, broad substrate scope, and excellent functional group compatibility. The resulting difluoroalkyl ketones can serve as versatile building blocks for the synthesis of various useful fluorinated compounds.
Supported ionic liquids as green catalyst for 2‐butanol synthesis from transesterification of sec‐butyl acetate
Authors: Yang Jinbei , Zeng Ting , Cai Dongren , Li Ling , Tang Wenli , Hong Ruoyu , Qiu Ting 
Published: July 2016

AbstractTwo supported ionic liquids using molecular sieve SBA‐15 as supporter were prepared and employed as efficient catalysts for the synthesis of 2‐butanol (SBOH) via the transesterification of sec‐butyl acetate and methanol (MeOH). [SBA‐15‐Ps‐im]HSO4 performed better in the catalytic activity and was chosen for further studying the influence of experimental conditions. The effects of various parameters, such as the catalyst dosage, initial reactant molar ratio, and reaction time on the reaction were investigated systematically. The maximum conversion of sec‐butyl acetate (89.2%) was obtained under the optimum reaction conditions. In addition, the catalyst of supported ionic liquids can be easily separated by simple filtration, and the reusability test indicates that the catalyst has outstanding utility for repeated use. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Characterization and properties of LDPE film with gallic‐acid‐based oxygen scavenging system useful as a functional packaging material
Authors: Ahn Byung Joon , Gaikwad Kirtiraj K. , Lee Youn Suk 
Published: July 2016

ABSTRACTWe prepared and characterized active, oxygen‐scavenging, low density polyethylene (LDPE) films from a non‐metallic‐based oxygen scavenging system (OSS) containing 1, 3, 5, 10, and 20% of gallic acid (GA) and potassium chloride (PC). We compared the surface morphology and mechanical, permeability, and optical properties of the oxygen‐scavenging LDPE film with those of pure LDPE film. The surface morphology, gas barrier, and thermal properties indicate that the OSS was well incorporated into the LDPE film structure. The surface roughness of the film increased with the amount of oxygen scavenging material. The oxygen and water vapor permeability of the developed film also increased with the amount of oxygen scavenging material, though its elongation decreased. The oxygen scavenging capability of the prepared film was analyzed at different temperatures. The initial oxygen content (%) in the vial headspace, 20.90%, decreased to 16.6% at 4 °C, 14.6% at 23 °C, and 12.7% at 50 °C after 7 days of storage with the film containing 20% OSS. The film impregnated with 20% organic oxygen scavenging material showed an effective oxygen scavenging capacity of 0.709 mL/cm2 at 23 °C. Relative humidity triggered the oxygen scavenging reaction. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44138.
Spray‐dried microparticles composed of cinnamoyl poly(N‐isopropylacrylamide‐co‐hydroxyethylacrylate) and gold nanoparticle
Authors: Zhang Hong , Kim Jin‐Chul 
Published: July 2016

ABSTRACTTemperature‐ and NIR irradiation‐responsive microparticles composed of cinnamoyl poly(N‐isopropylacrylamide‐co‐hydroxyethylacrylate) [CinP(NIPAM‐HEA)] and gold nanoparticle (GNP) were prepared by a spray‐drying method. According to the cloud points determined by an optical method, the HEA content in P(NIPAM‐HEA) had no marked effect on the lower critical solution temperature (LCST). However, the cinnamoyl group content in CinP(NIPAM‐HEA) had a significant effect on the LCST. The LCSTs determined by a calorimetric method was in agreement with those determined by an optical method. The hydrodynamic mean diameter of gold nanoparticle (GNP) prepared by reducing gold ions was about 30 nm and it seemed to be a nanosphere on TEM photo. Spray‐dried CinP(NIPAM‐HEA) microparticles containing GNP was 1.5 μm to 12 μm in diameter on SEM photo. Gold was detected on the energy‐dispersive X‐ray spectrum of the microparticles. The amount of FITC‐dextran released for 12 h from the microparticles was much higher at temperatures above the LCST (at 37 °C and 45 °C) than below the LCST (at 20 °C and 25 °C). The cumulative release amount in 12 h was only about 3% without NIR irradiation, whereas the value was about 26.5% when NIR was irradiated to the microparticle suspension. The photothermal energy generated by GNP was believed to render the thermosensitive copolymers de‐swollen and hydrophobic, allowing for the active release of dye from the microparticles. The NIR irradiation‐responsive GNP‐loaded microparticles could be applied to the development of NIR‐responsive drug carriers which release their contents in response to an external stimulus (i.e., NIR irradiation). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44141.
Helical Polyacetylene‐Based Switchable Chiral Columnar Phases: Frustrated Chain Packing and Two‐Way Shape Actuator
Authors: Wang Jun , Liu Xiao‐Qing , Ren Xiang‐Kui , Zhang Ben , Yang Shuang , Cao Yu , Liu Feng , Lotz Bernard , Chen Er‐Qiang 
Published: July 2016

AbstractChiral columns formed by a helical cis‐polyphenylacetylene (PPA) derivative P1 are reversibly switched during a phase transition between two chiral columnar phases: the frustrated Φh3D‐SL phase containing four chains at low temperature and a hexagonal columnar phase Φh at high temperature, accompanied by a simultaneous conformational change. The helix–helix transition along the PPA backbone during the Φh3D‐SL‐Φh transition makes the uniaxially oriented P1 capable of reversibly and reproducibly elongating (132 %) upon heating and contracting upon cooling, exhibiting the behavior of a two‐way shape actuator.
Constraining the Milky Way assembly history with Galactic Archaeology
Authors: Minchev I. 
Published: July 2016

AbstractThe aim of Galactic Archaeology is to recover the evolutionary history of the Milky Way from its present day kinematical and chemical state. Because stars move away from their birth sites, the current dynamical information alone is not sufficient for this task. The chemical composition of stellar atmospheres, on the other hand, is largely preserved over the stellar lifetime and, together with accurate ages, can be used to recover the birthplaces of stars currently found at the same Galactic radius. In addition to the availability of large stellar samples with accurate 6D kinematics and chemical abundance measurements, this requires detailed modeling with both dynamical and chemical evolution taken into account. An important first step is to understand the variety of dynamical processes that can take place in the Milky Way, including the perturbative effects of both internal (bar and spiral structure) and external (infalling satellites) agents. We discuss here (1) how to constrain the Galactic bar, spiral structure, and merging satellites by their effect on the local and global disc phase‐space, (2) the effect of multiple patterns on the disc dynamics, and (3) the importance of radial migration and merger perturbations for the formation of the Galactic thick disc. Finally, we discuss the construction of Milky Way chemo‐dynamical models and relate to observations. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuous precipitation of process related impurities from clarified cell culture supernatant using a novel coiled flow inversion reactor (CFIR)
Authors: Kateja Nikhil , Agarwal Harshit , Saraswat Aditya , Bhat Manish , Rathore Anurag S. 
Published: July 2016

AbstractCoiled Flow Inverter Reactor (CFIR) has recently been explored for facilitating continuous operation of several unit operations involved in downstream processing of biopharmaceuticals such as viral inactivation and protein refolding. The application of CFIR for continuous precipitation of clarified cell culture supernatant has been explored. The pH based precipitation is optimized in the batch mode and then in the continuous mode in CFIR using a design of experiments (DOE) study. Improved clearance of host cell DNA (52× vs. 39× in batch), improved clearance of host cell proteins (HCP) (7× vs. 6× in batch) and comparable recovery (90 vs. 91.5 % in batch) are observed along with six times higher productivity. To further demonstrate wider applicability of CFIR in performing continuous precipitation, two more case studies involving use of two different precipitation protocols (CaCl2 based and caprylic acid based) are also performed. In both cases, clearance of host cell DNA, HCP, and product recovery are found to be comparable or better in CFIR than in batch operations. Moreover, increase in productivity of 16 times (CaCl2 based) and eight times (caprylic acid based) is obtained for the two precipitation protocols, respectively. The data clearly demonstrate that CFIR can be seamlessly integrated into a continuous bioprocess train for performing continuous precipitation of clarified cell culture supernatant. To our knowledge this is the first report of such use.
Identification and Synthesis of Branched Wax‐type Esters, Novel Surface Lipids from the Spider Argyrodes elevatus (Araneae: Theridiidae)
Authors: Chinta Satya Prabhakar , Goller Stephan , Uhl Gabriele , Schulz Stefan 
Published: July 2016

The analysis of cuticular extracts from the kleptoparasitic spider Argyrodes elevatus revealed the presence of unusual esters, new for arthropods. These novel compounds proved to be methyl‐branched long‐chain fatty acid esters with methyl branches located either close or remote from the internally located ester group. The GC/MS analysis of the prosoma lipid blend from the male cuticle contained one major component, undecyl 2‐methyltridecanoate (1). In contrast, four major wax‐type esters, 2‐methylundecyl 2,8‐dimethylundecanoate (2), 2,8‐dimethylundecyl 2,8‐dimethylundecanoate (3), heptadecyl 4‐methylheptanoate (4), and 14‐methylheptadecyl 4‐methylheptanoate (5), were identified in the lipid blend of female prosomata. Structure assignments were based on mass spectra, gas chromatographic retention indices, and microderivatization. Unambiguous proof of postulated structures was ensured by an independent synthesis of all five esters. Preferentially, odd‐numbered carbon chains pointed to a distinct biosynthetic pathway, different from that of common fatty acids, because one or two C3 starter units are incorporated during the biosynthesis of all acid and alcohol building blocks present in the five esters. The striking sexual dimorphism together with the unique biosynthesis points to a function of the esters in chemical communication of the spiders, although no behavioral data are currently available to test this assumption.
Three New Ergot Alkaloids from the Fruiting Bodies of Xylaria nigripes (Kl.) Sacc.
Authors: Hu Dongbao , Li Ming 
Published: July 2016

Three new ergot alkaloids, xylanigripones A – C (1 – 3) together with three known compounds, agroclavine (4), 8,9‐didehydro‐10‐hydroxy‐6,8‐dimethylergolin (5), and (6S)‐agroclavine N‐oxide (6) were isolated from the fungus Xylaria nigripes (Kl.) Sacc. Their structures were elucidated by comprehensive spectroscopic analyses and high‐resolution mass spectrometry as well as by comparison with the literature. The absolute configuration was determined by Density Functional Theory (DFT) calculation methods. In addition, all of the compounds were evaluated for bioactivity via a cytotoxicity assay, an acetylcholinesterase inhibition assay and a cholesterol ester transfer protein inhibition assay.
An Activator of an Adenylation Domain Revealed by Activity but Not Sequence Homology
Authors: Saha Shalini , Rokita Steven E. 
Published: July 2016

AbstractNonribosomal peptide synthetases (NRPSs), which are responsible for synthesizing many medicinally important natural products, frequently use adenylation domain activators (ADAs) to promote substrate loading. Although ADAs are usually MbtH‐like proteins (MLPs), a new type of ADA appears to promote an NRPS‐dependent incorporation of a dihydropyrrole unit into sibiromycin. The adenylation and thiolation didomain of the NRPS SibD catalyzes the adenylation of a limited number of amino acids including l‐Tyr, the precursor in dihydropyrrole biosynthesis, as determined by a standard radioactivity exchange assay. LC‐MS/MS analysis confirmed loading of l‐Tyr onto the thiolation domain. SibB, a small protein with no prior functional assignment or sequence homology to MLPs, was found to promote the exchange activity. MLPs from bacteria expressing homologous biosynthetic pathways were unable to replace this function of SibB. The discovery of this new type of ADA demonstrates the importance of searching beyond the conventional MLP standard for proteins affecting NRPS activity.
Biosynthetic Gene Cluster for Surugamide A Encompasses an Unrelated Decapeptide, Surugamide F
Authors: Ninomiya Akihiro , Katsuyama Yohei , Kuranaga Takefumi , Miyazaki Masayuki , Nogi Yuichi , Okada Shigeru , Wakimoto Toshiyuki , Ohnishi Yasuo , Matsunaga Shigeki , Takada Kentaro 
Published: July 2016

AbstractGenome mining is a powerful method for finding novel secondary metabolites. In our study on the biosynthetic gene cluster for the cyclic octapeptides surugamides A–E (inhibitors of cathepsin B), we found a putative gene cluster consisting of four successive non‐ribosomal peptide synthetase (NRPS) genes, surA, surB, surC, and surD. Prediction of amino acid sequence based on the NRPSs and gene inactivation revealed that surugamides A–E are produced by two NRPS genes, surA and surD, which were separated by two NRPS genes, surB and surC. The latter genes are responsible for the biosynthesis of an unrelated peptide, surugamide F. The pattern of intercalation observed in the sur genes is unprecedented. The structure of surugamide F, a linear decapeptide containing one 3‐amino‐2‐methylpropionic acid (AMPA) residue, was determined by spectroscopic methods and was confirmed by solid‐phase peptide synthesis.
Design of Raspberry‐Shaped Microcarriers with Adjustable Protrusions and Functional Groups for the Improvement of Lipase Immobilization and Biocatalysis: Environmentally Friendly Esterification of Oleic Acid for Biodiesel
Authors: Tian Lei , Zhao Panpan , Li Xue , Ali Zafar , Li Xiangjie , Zhang Baoliang , Zhang Hepeng , Zhang Qiuyu 
Published: July 2016

AbstractRaspberry‐shaped microparticles with adjustable protrusions and functional groups were synthesized and applied as carriers for the immobilization of lipase. The structural advantages of the raspberry‐shaped microcarriers with immobilized lipase (RM‐IL) are not only that the protrusions are constructed to play the role of a spacer arm, but the block structure enhances the bioactivity of lipase at the oil–water interface. The activation method used for the carrier has a significant effect on the performance of immobilized lipase. RM‐IL prepared by carboxylic acid activation has a 3.5‐fold increase of activity compared with that from amine activation and generates a fourfold increase of protein bound to 164 mg g−1 of carrier. Finally, RM‐IL is used as an environmentally friendly and high‐efficiency biocatalyst to catalyze the esterification of oleic acid for biodiesel under mild conditions, and the conversion can reach up to 82.1 %. Above all, raspberry‐shaped microcarriers prepared by an improved seed emulsion polymerization have prospects for industrialization.