bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploiting Cofactor Versatility to Convert a FAD‐Dependent Baeyer–Villiger Monooxygenase into a Ketoreductase
Authors: Xu Jian , Peng Yongzhen , Wang Zhiguo , Hu Yujing , Fan Jiajie , Zheng He , Lin Xianfu , Wu Qi 
Published: August 2019

AbstractCyclohexanone monooxygenases (CHMOs) show very high catalytic specificity for natural Baeyer–Villiger (BV) reactions and promiscuous reduction reactions have not been reported to date. Wild‐type CHMO from Acinetobacter sp. NCIMB 9871 was found to possess an innate, promiscuous ability to reduce an aromatic α‐keto ester, but with poor yield and stereoselectivity. Structure‐guided, site‐directed mutagenesis drastically improved the catalytic carbonyl‐reduction activity (yield up to 99 %) and stereoselectivity (ee up to 99 %), thereby converting this CHMO into a ketoreductase, which can reduce a range of differently substituted aromatic α‐keto esters. The improved, promiscuous reduction activity of the mutant enzyme in comparison to the wild‐type enzyme results from a decrease in the distance between the carbonyl moiety of the substrate and the hydrogen atom on N5 of the reduced flavin adenine dinucleotide (FAD) cofactor, as confirmed using docking and molecular dynamics simulations.
Organocatalytic Enantioselective Functionalization of Unactivated Indole C(sp3)−H Bonds
Authors: Ma Dengke , Zhang Zhihan , Chen Min , Lin Zhenyang , Sun Jianwei 
Published: August 2019

AbstractDescribed here is a direct catalytic asymmetric functionalization of unactivated alkyl indoles using organocatalysis. In the presence of an effective chiral urea catalyst and a phosphoric acid additive, the intermolecular C−C bond formation between alkyl indoles and trifluoropyruvates proceeded with high efficiency and enantiocontrol. Unlike previous asymmetric C(sp3−H) functionalizations of α‐azaarenes, this process does not require the use of either a strong base or an electron‐deficient substrate. The excellent enantiocontrol is particularly noteworthy in view of the severe background reaction as well as the complete inability of other types of catalysts evaluated. Control experiments, kinetic studies, and DFT calculations provided important insights into the mechanism.
Synthesis and nonisothermal crystallization kinetics of biodegradable poly(ethylene terephthalate‐co‐ethylene succinate)s
Authors: Li Wenxu , Guan Xinmei , Zhan Yifei , Xiao Hongyan , Lin Shaojian , Lan Jianwu 
Published: August 2019

ABSTRACTIn the current work, a series of biodegradable poly(ethylene terephthalate‐co‐ethylene succinate)s (P[ET‐co‐ES]s) were prepared via a traditional melting polycondensation method. First of all, the structures of prepared copolymers were characterized by nuclear magnetic resonance and Fourier transform infrared measurements. Meanwhile, the thermal properties of prepared samples were analyzed by differential scanning calorimetry and thermogravimetric analysis measurements, respectively. Subsequently, the mechanical properties of the P(ET‐co‐ES)s were evaluated, the tensile strength of P(ET‐co‐ES)s decreased with increasing of PES content in copolymer, however, corresponding P(ET‐co‐ES)s exhibited better elongation at break. Next, the biodegradability of P(ET‐co‐ES)s was evaluated using lipase as degrading enzyme. The results presented that the biodegradability of P(ET‐co‐ES)s improved with PES content, the corresponding results were supported by scanning electron microscopy test. Finally, the Mo's modified Avrami equation was employed to analyze the nonisothermal crystallization kinetics of prepared copolymers. The results showed the addition of the PES component improved the crystallization properties of the prepared P(ET‐co‐ES)s. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48422.
Enabling High Performance Potassium‐Based Dual‐Graphite Battery Cells by Highly Concentrated Electrolytes
Authors: Münster Patrick , Heckmann Andreas , Nölle Roman , Winter Martin , Beltrop Kolja , Placke Tobias 
Published: August 2019

AbstractThis work studies an advanced potassium dual‐graphite battery (DGB) cell system based on a highly concentrated electrolyte (HCE), i. e., potassium bis(fluorosulfonylimide) (KFSI) in ethyl methyl carbonate (EMC). Structural and electrochemical properties of the designated KFSI/EMC electrolyte are investigated and discussed at different concentrations (1.0 M–4.0 M). Ionic aggregation at high salt concentrations leads to enhanced electrochemical stability and pushes the oxidative stability limit beyond 5 V vs. K|K+. Based on those results, the electrochemical performance with graphite as positive and negative electrode active material in graphite||K metal cells is presented. For potassium intercalation into graphite, an impressive capacity retention and rate capability is found for the EC‐free HCEs (EC=ethylene carbonate), outperforming potassium electrolytes used in the literature. New insights into the formation of the solid electrolyte interphase (SEI) are presented and confirm improved electrochemical performance. Additionally, high salt concentrations in the electrolyte stabilize the aluminium (Al) current collector and enable reversible intercalation of FSI anions into the graphite positive electrode. Furthermore, reversible cycling in DGB cells is shown and a capacity fading mechanism based on parasitic side reactions causing K+ ion accumulation in the negative electrode, followed by K metal plating, is comprehensively evaluated.
Oleaginous yeast Meyerozyma guilliermondii shows fermentative metabolism of sugars in the biosynthesis of ethanol and converts raw glycerol and cheese whey permeate into polyunsaturated fatty acids
Authors: Fabricio Mariana Fensterseifer , Valente Patricia , Záchia Ayub Marco Antônio 
Published: August 2019

AbstractWe studied the biotechnological potential of the recently isolated yeast Meyerozyma guilliermondii BI281A to produce polyunsaturated fatty acids and ethanol, comparing products yields using glucose, raw glycerol from biodiesel synthesis, or whey permeate as substrates. The yeast metabolism was evaluated for different C/N ratios (100:1 and 50:1). Results found that M. guilliermondii BI281A was able to assimilate all tested substrates, and the most efficient conversion obtained was observed using raw glycerol as carbon source (C/N ratio 50:1), concerning biomass formation (5.67 g·L−1) and lipid production (1.04 g·L−1), representing 18% of dry cell weight. Bioreactors experiments under pH and aeration‐controlled conditions were conducted. Obtained fatty acids were composed of ~67% of unsaturated fatty acids, distributed as palmitoleic acid (C16:1, 9.4%), oleic acid (C18:1, 47.2%), linoleic acid (C18:2 n−6, 9.6%), and linolenic acid (C18:3 n−3, 1.3%). Showing fermentative metabolism, which is unusual for oleaginous yeasts, M. guilliermondii produced 13.7 g·L−1 of ethanol (yields of 0.27) when growing on glucose medium. These results suggest the promising use of this uncommonly studied yeast to produce unsaturated fatty acids and ethanol using cheap agro‐industrial residues as substrates in bioprocess.
Mechanism and Substituent Effects of Benzene Arylation via a Phenyl Cation Strategy: A Density Functional Theory Study
Authors: Li Xiaoyan , Sun Ling , Zhang Qiaochu , Li Shijun , Wang Yang , Wei Donghui , Zhang Wenjing , Lan Yu 
Published: August 2019

AbstractIn this study, density functional theory (DFT) calculations were performed to gain insight into the possible reaction mechanism and substituent effects of benzene arylation at the molecular level. The results showed that both [Me3Si]+[WCA]− and [Et3Si]+[WCA]− promoted the reaction. The whole catalytic cycle generally involved three processes, namely, carbocation formation, Wheland intermediate formation, and catalyst regeneration. For the second process, the stepwise mechanism (C−C coupling followed by proton transfer) was shown to be preferred over the concerted mechanism, with successive [1,2]/[1,4]‐proton transfer as the preferred pathway. C−C coupling, rather than C−H insertion, was shown to be the rate‐determining step of the reaction, which was consistent with the kinetic isotope effect experimental results. Bond dissociation energy calculations showed that the ortho‐TMS substituent played a major role in activating the C−F bond to facilitate phenyl cation formation, leading to the most weakly C−Cl bonded intermediate, which facilitated the C−C coupling. Ortho‐phenyl substituents resulted in more severe steric hindrance of fluoride abstraction and a weaker C−H⋅⋅⋅π interaction in the C−C coupling transition state compared with meta‐phenyl substituents. Better stabilization of the cation center by an electron‐rich meta‐substituent was concluded to be the main reason for the better yield obtained compared with substrates containing an electron‐deficient meta‐substituent.
Electrochemical Behavior of Cytochrome C Immobilized in a Magnetically Induced Mesoporous Framework
Authors: Melo Antonio F. A. A. , Sedenho Graziela C. , Osica Izabela , Ariga Katsuhiko , Crespilho Frank N. 
Published: August 2019

AbstractProtein immobilization on electrode surfaces remains a technological challenge and is decisive in enhancing biological properties with simplified operational steps. In view of proposing a new direction for protein immobilization, we report the development of a mesoporous framework resulting from the magnetically induced assembly of magnetite nanoparticles decorated with near‐monodisperse gold nanoparticles onto an indium‐tin‐oxide electrode. With an electrochemically active surface area of about 72 cm2 and pores with an average size of 31±1 nm, this magnetically induced mesoporous framework is suitable for the immobilization of small redox proteins. As a proof‐of‐concept, we show the electrochemical process of cytochrome c, where the mesoporous electrode provided a fourfold enhancement for the faradaic currents in comparison to standard polycrystalline gold electrodes.
Enhanced Electrochemical Properties of LiNi0.8Co0.1Mn0.1O2 Cathode Materials Modified with Lithium‐Ion Conductive Coating LiNbO3
Authors: Hu Guorong , Tao Yong , Lu Yan , Fan Ju , Li Luyu , Xia Jin , Huang Yong , Zhang Zhiyong , Su Haodong , Cao Yanbing 
Published: August 2019

AbstractAs a promising cathode material for lithium‐ion batteries, nitrogen‐rich LiNi0.8Co0.1Mn0.1O2 (NCM811) attracts great attention for its high specific capacity, but the rapid capacity decline of NCM811 in the process of charge/discharge restricts its extensive application. To alleviate the capacity decline for NCM811, a solid electrolyte LiNbO3 material with lithium‐ion diffusion and electron conduction activity was successfully coated on the surface of NCM811 by adopting a simple two‐step method, and the amount of the LiNbO3 coating layer was investigated. Powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy were used to characterize the as‐prepared cathode materials. The experimental results revealed that the LiNbO3 played a role in reducing surface residual alkalis and protecting NCM811 from erosion by electrolyte. When the weight ratio of LiNbO3 and NCM811 was 1 %, the corresponding 1 wt % LNO@NCM material displayed the best cycle performance and rate capability, whose capacity retention at 1 C after 200 cycles, and discharge capacity at 10 C are 90.1 % and 122.7 mAh g−1, respectively.
Sulfur‐/Nitrogen‐Rich Albumen Derived “Self‐Doping” Graphene for Sodium‐Ion Storage
Authors: Li Siyuan , Li Zeheng , Cao Gaoyao , Ling Min , Ji Jiapeng , Zhao Dian , Sha Ying , Gao Xuehui , Liang Chengdu 
Published: August 2019

AbstractThe development of sodium‐ion batteries (SIBs) is hindered by the rapid reduction in reversible capacity of carbon‐based anode materials. Outside‐in doping of carbon‐based anodes has been extensively explored. Nickel and NiS2 particles embedded in nitrogen and sulfur codoped porous graphene can significantly improve the electrochemical performance. Herein a built‐in heteroatom “self‐doping” of albumen‐derived graphene for sodium storage is reported. The built‐in sulfur and nitrogen in albumen act as the doping source during the carbonization of proteins. The sulfur‐rich proteins in albumen can also guide the doping and nucleation of nickel sulfide nanoparticles. Additionally, the porous architecture of the carbonized proteins is achieved through removable KCl/NaCl salts (medium) under high‐temperature melting conditions. During the carbonization process, nitrogen can also reduce the carbonization temperature of thermally stable carbon materials. In this work, the NS‐graphene delivered a specific capacity of 108.3 mAh g−1 after 800 cycles under a constant current density of 500 mA g−1. In contrast, the Ni/NiS2/NS‐graphene maintained a specific capacity of 134.4 mAh g−1; thus the presence of Ni/NiS2 particles improved the electrochemical performance of the whole composite.
A Comprehensive Investigation of a Zwitterionic GeI Dimer with a 1,2‐Dicationic Core
Authors: Béland Vanessa A. , Wang Zhiqiang , Macdonald Charles L. B. , Sham Tsun‐Kong , Ragogna Paul J. 
Published: August 2019

AbstractThe reductive dehalogenation of a zwitterionic GeII species to make a zwitterionic GeI dimer with a 1,2‐dicationic core is reported herein. To the root of the stability of this compound, the molecular and electronic structures were comprehensively characterized and investigated using crystallographic, spectroscopic, and computational methods. It was determined that the Ge centers are attracted because they are both electron‐rich and positively charged. A comparison to the electronic structure in triphosphenium cations revealed varying degrees of covalent bonding and that this difference can be distinguished spectroscopically.
Is job control always beneficial? Exploring its nonlinearity in creativity and in‐role performance
Authors: Du Yana , Zhang Li , Bu Qiong , Kurniawan Aldo 
Published: August 2019

AbstractThis study draws on resource allocation theory to examine the relationship between job control and two kinds of job performance, namely employee creativity and in‐role performance, as well as to investigate whether supervisor encouragement of creativity moderates these two potentially nonlinear relationships. To test the proposed model, we collected data from 234 employees in Indonesia. The results show that job control has an inverted U‐shaped relationship with employee creativity, but a U‐shaped relationship with in‐role performance. Supervisor encouragement of creativity moderates both relationships, such that the control–creativity relationship becomes U‐shaped, while the control–in‐role performance relationship becomes inverted U‐shaped when supervisor encouragement of creativity is high. Implications for managers on how to provide resources to employees are discussed.
Nature of Synergy between Brønsted and Lewis Acid Sites in Sn–Beta Zeolites for Polyoxymethylene Dimethyl Ethers Synthesis
Authors: Baranowski Christophe J. , Roger Maneka , Bahmanpour Ali M. , Kröcher Oliver 
Published: August 2019

AbstractThe role of Lewis and Brønsted acid sites and their potential synergy remains ambiguous for the production of polyoxymethylene dimethyl ethers (OME), which are suitable as a Diesel substitute. Here, this synergistic effect was investigated by using a series of beta polymorph A (BEA) zeolites with various degrees of Brønsted and Lewis acidity. Lewis acidity was introduced in dealuminated zeolites by Sn grafting in dichloromethane. These sites were only active in paraformaldehyde decomposition, OME growth, and acetalization. The Brønsted acid sites arising from bridging hydroxyl groups were active for all reaction steps, and notably for trioxane ring‐opening and dissociation to formaldehyde (FA), which did not occur on the Lewis acid sites. Presence of both Lewis and Brønsted acid sites led to a four‐fold increase in turnover frequency and a significant decrease of byproduct formation compared with the parent zeolite during OME synthesis from dimethoxymethane and trioxane. The synergistic effect between both types of acid sites is explained by FA insertion on Lewis acid sites leading to OME growth. Interaction between tetrahedral Sn and the carbonyl group of FA resulted in an activated carbonyl bond, which was likely the initial step for insertion of FA into OME.
Diversity matters: Effects of density compensation in pollination service during rainfall shift
Authors: Mukherjee Ronita , Deb Rittik , Devy Soubadra M. 
Published: August 2019

Abstract

Extreme weather events are increasing in frequency due to the warming climate. Such extremities can jeopardize ecosystem services and create economic imbalances. Tropical developing countries are predicted to suffer the maximum consequences of such events.

We examined the impact of such an event—extreme rainfall fluctuation—on a critical ecosystem service—pollination, which can be intricately linked to a country's economy. We performed this study in a dominant peri‐urban vegetable hub of an agriculture‐dependent developing country.

We found that the yield of all pollinator‐dependent crops grown across a large spatial scale (district) over multiple years (six) drastically declined with the decrease in rainfall.

At the local scale, we found that the dominant crop (representative horticultural crop) had a significant drop in yield during drought, likely due to the production of fewer female flowers and a significant shift in the pollinator community.

We found that Trigona sp. (one of the four pollinators) was the critical pollinator positively influencing fruit‐to‐flower ratio (FFR) (an indicator of pollination service) in the normal rainfall year. However, despite its sharp decline during drought, the FFR remained unaffected. We found that during drought, Apis dorsata was crucial in maintaining FFR and compensated for the decline of the critical pollinator across 67% farmlands.

Our study demonstrates the role of ecosystem stabilizing mechanism rescuing the crucial ecosystem service during climatic variability over the temporal scale.
Cytometry by time of flight identifies distinct signatures in patients with systemic sclerosis, systemic lupus erythematosus and Sjögrens syndrome
Authors: van der Kroef Maarten , van den Hoogen Lucas L. , Mertens Jorre S. , Blokland Sofie L.M. , Haskett Scott , Devaprasad Abhinandan , Carvalheiro Tiago , Chouri Eleni , Vazirpanah Nadia , Cossu Marta , Wichers Catherina G.K , Silva‐Cardoso Sandra C. , Affandi Alsya J. , Bekker Cornelis P.J. , Lopes Ana P. , Hillen Maarten R. , Bonte‐Mineur Femke , Kok Marc R. , Beretta Lorenzo , Rossato Marzia , Mingueneau Michaël , van Roon Joel A.G. , Radstake Timothy R.D.J 
Published: August 2019

AbstractSystemic sclerosis (SSc), systemic lupus erythematosus (SLE) and primary Sjögrens syndrome (pSS) are clinically distinct systemic autoimmune diseases (SADs) that share molecular pathways. We quantified the frequency of circulating immune‐cells in 169 patients with these SADs and 44 healty controls (HC) using mass‐cytometry and assessed the diagnostic value of these results. Alterations in the frequency of immune‐cell subsets were present in all SADs compared to HC. Most alterations, including a decrease of CD56hi NK‐cells in SSc and IgM+ Bcells in pSS, were disease specific; only a reduced frequency of plasmacytoid dendritic cells was common between all SADs Strikingly, hierarchical clustering of SSc patients identified 4 clusters associated with different clinical phenotypes, and 9 of the 12 cell subset‐alterations in SSc were also present during the preclinical‐phase of the disease. Additionally, we found a strong association between the use of prednisone and alterations in B‐cell subsets. Although differences in immune‐cell frequencies between these SADs are apparent, the discriminative value thereof is too low for diagnostic purposes. Within each disease, mass cytometry analyses revealed distinct patterns between endophenotypes. Given the lack of tools enabling early diagnosis of SSc, our results justify further research into the value of cellular phenotyping as a diagnostic aid.
Rates of rockwall slope erosion in the upper Bhagirathi catchment, Garhwal Himalaya
Authors: Orr Elizabeth N. , Owen Lewis A. , Saha Sourav , Caffee Marc W. 
Published: August 2019

ABSTRACTRockwall slope erosion is defined for the upper Bhagirathi catchment using cosmogenic Beryllium‐10 (10Be) concentrations in sediment from medial moraines on Gangotri glacier. Beryllium‐10 concentrations range from 1.1 ± 0.2 to 2.7 ± 0.3 × 104 at/g SiO2, yielding rockwall slope erosion rates from 2.4 ± 0.4 to 6.9 ± 1.9 mm/a. Slope erosion rates are likely to have varied over space and time and responded to shifts in climate, geomorphic and/or tectonic regime throughout the late Quaternary. Geomorphic and sedimentological analyses confirm that the moraines are predominately composed of rockfall and avalanche debris mobilized from steep relief rockwall slopes via periglacial weathering processes. The glacial rockwall slope erosion affects sediment flux and storage of snow and ice at the catchment head on diurnal to millennial timescales, and more broadly influences catchment configuration and relief, glacier dynamics and microclimates. The slope erosion rates exceed the averaged catchment‐wide and exhumation rates of Bhagirathi and the Garhwal region on geomorphic timescales (103−105 years), supporting the view that erosion at the headwaters can outpace the wider catchment. The 10Be concentrations of medial moraine sediment for the upper Bhagirathi catchment and the catchments of Chhota Shigri in Lahul, northern India and Baltoro glacier in Central Karakoram, Pakistan show a tentative relationship between 10Be concentration and precipitation. As such there is more rapid glacial rockwall slope erosion in the monsoon‐influenced Lesser and Greater Himalaya compared to the semi‐arid interior of the orogen. Rockwall slope erosion in the three study areas, and more broadly across the northwest Himalaya is likely governed by individual catchment dynamics that vary across space and time. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons, Ltd.