bluuebunny/crossref_metadata_2025_split huggingface dataset:
Switch in Selectivity for Formal Hydroalkylation of 1,3‐Dienes and Enynes with Simple Hydrazones
Authors: Lv Leiyang , Yu Lin , Qiu Zihang , Li Chao‐Jun 
Published: January 2020

AbstractControlling reaction selectivity is a permanent pursuit for chemists. Regioselective catalysis, which exploits and/or overcomes innate steric and electronic bias to deliver diverse regio‐enriched products from the same starting materials, represents a powerful tool for divergent synthesis. Recently, the 1,2‐Markovnikov hydroalkylation of 1,3‐dienes with simple hydrazones was reported to generate branched allylic compounds when a nickel catalyst was used. As part of the effort, shown here is that a complete switch of Markovnikov to anti‐Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro‐metallation across the metal‐π‐allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3‐enynes.
Gold(I)‐Catalyzed Cycloisomerization of 3‐Alkoxyl‐1,6‐diynes: A Facile Access to Bicyclo[2.2.1]hept‐5‐en‐2‐ones
Authors: Hu Chao , Wang Tao , Rudolph Matthias , Oeser Thomas , Asiri Abdullah M. , Hashmi A. Stephen K. 
Published: January 2020

AbstractA novel gold‐catalyzed cycloisomerization of 1,6‐diynes was achieved, providing an atom‐economic approach to a diverse set of bicyclo[2.2.1]hept‐5‐en‐2‐ones in moderate to good yields. With unsymmetrical starting materials with two different internal alkynyl substituents, to some extent, the regioselectivity could be controlled by both electronic and steric factors. This unprecedented reactivity pattern may inspire new and unconventional strategies for the preparation of bridged ring systems.
Parahydrogen‐Induced Hyperpolarization of Gases
Authors: Kovtunov Kirill V. , Koptyug Igor V. , Fekete Marianna , Duckett Simon B. , Theis Thomas , Joalland Baptiste , Chekmenev Eduard Y. 
Published: January 2020

AbstractImaging of gases is a major challenge for any modality including MRI. NMR and MRI signals are directly proportional to the nuclear spin density and the degree of alignment of nuclear spins with applied static magnetic field, which is called nuclear spin polarization. The level of nuclear spin polarization is typically very low, i.e., one hundred thousandth of the potential maximum at 1.5 T and a physiologically relevant temperature. As a result, MRI typically focusses on imaging highly concentrated tissue water. Hyperpolarization methods transiently increase nuclear spin polarizations up to unity, yielding corresponding gains in MRI signal level of several orders of magnitude that enable the 3D imaging of dilute biomolecules including gases. Parahydrogen‐induced polarization is a fast, highly scalable, and low‐cost hyperpolarization technique. The focus of this Minireview is to highlight selected advances in the field of parahydrogen‐induced polarization for the production of hyperpolarized compounds, which can be potentially employed as inhalable contrast agents.
Kinetic study of the multistep thermo‐oxidative degradation of thermosetting siloxane‐containing polyimide and unmodified polyimide
Authors: Liu Yi , Xu Xiaozhou , Mo Song , Lan Bangwei , Zhu Caizhen , Xu Jian , Li Cuihua , Fan Lin 
Published: January 2020

AbstractIn this study, the thermo‐oxidative degradation kinetics of thermosetting siloxane‐containing polyimide (SPI) and unmodified polyimide (PI) were comparatively studied to reveal effect of siloxane on the thermo‐oxidative stability, and to understand how they behave under elevated temperature. Results of thermogravimetirc analysis complemented by structural and morphological observations indicate two individual processes compose thermo‐oxidative degradation of SPI and PI. Therefore, different kinetic triplets are employed to describe the two processes. It is found that the degradation activation energy (E) of the first process for SPI is lower than that for PI, while in the second process, the E value of SPI goes beyond that of PI. The difference of structural changes between SPI and PI during thermo‐oxidative degradation offers rational explanation. The oxidation of siloxane in the first process results in weight loss of SPI at relatively lower temperature, while the formed silica‐type structures retard the second degradation process, making SPI exhibited a slower degradation rate than PI. In addition, the two constituent processes for thermo‐oxidative degradation of SPI and PI obey the Avrami‐Erofeev models. Based on the obtained kinetic parameters, simulations of thermo‐oxidative degradation for both SPI and PI were successfully realized, which gives a precise mathematical description of their degradation behaviors.
Seventeen new microsatellites for Tamarix gallica and cross‐amplification in Tamarix species
Authors: Terrones Alejandro , Juan Ana 
Published: January 2020

PremiseMicrosatellite markers were developed for the western Mediterranean tree Tamarix gallica (Tamaricaceae) as part of a study of its genetic diversity and structure.Methods and ResultsSeventeen microsatellite markers were developed for T. gallica, 14 of which were polymorphic. These microsatellites have di‐, tri‐, and tetranucleotide repeats with 1–13 alleles per locus and population. Levels of observed and expected heterozygosity ranged from 0.000 to 0.900 and from 0.000 to 0.863, respectively. Six microsatellites showed significant deviations from Hardy–Weinberg equilibrium in at least one population. Cross‐amplification in 19 Tamarix species showed a wide transferability to other species of the genus.ConclusionsThe 14 new polymorphic microsatellite markers will be used to assess the genetic diversity and population genetic structure of T. gallica. Additionally, the successful cross‐species amplification suggests their potential usefulness for investigating species delimitation and population genetics in the genus Tamarix.
Coexisting attractors in a fractional order hydro turbine governing system and fuzzy PID based chaos control
Authors: Rajagopal Karthikeyan , Jahanshahi Hadi , Jafari Sajad , Weldegiorgis Riessom , Karthikeyan Anitha , Duraisamy Prakash 
Published: January 2020

ABSTRACTA fractional order model of a hydro turbine governing system (FOHTGS) is derived using the Grunwald‐Letnikov's (GL) method. This model is developed using its integer order. Dynamical properties of FOHTGS, such as equilibrium point and its stability, Hopf bifurcation, and Lyapunov exponents (LEs) are investigated. Different dynamics of FOHTGS with respect to changing fractional order of the system and its parameter are studied. The FOHTGS shows multistability and coexisting attractors. To support the existence of multistability, some coexisting attractors are presented. A fuzzy PID based chaos control algorithm is designed and proposed in a hydro turbine governing system (HTGS). Numerical simulations are conducted to validate the effectiveness of the derived controller.
Mixed performance analysis of continuous switched systems with time‐varying random delay
Authors: Lien Chang‐Hua , Yu Ker‐Wei , Chang Hao‐Chin 
Published: January 2020

AbstractThis paper analyzes the asymptotic mean‐square stabilizability and mixed performance of switched time‐delay systems with time‐varying random delay via a switching signal selection. Some delay‐dependent LMI‐based criteria are proposed to achieve the switching signal design. Our approach is proposed to guarantee the mixed performance of the system under consideration by Wirtinger‐based inequality. A numerical example is given to show the main contribution of this paper.
Disturbance Observer Based Distributed Consensus Control Strategy of Multi‐Agent System with External Disturbance in a Standalone DC Microgrid
Authors: Krishna Metihalli Bhargavi , Narayana Sabhahit Jayalakshmi 
Published: January 2020

AbstractThis article proposes the secondary voltage control of microgrid on the basis of cooperative control of multi agent system. The distributed cooperative control utilizes disturbance observer technique to synchronize the DC bus voltage. The proposed controller achieves balanced power sharing among the battery energy storage units (BESUs) in the presence of external disturbances in heterogeneous microgrid (MG) network. The dynamics of heterogeneous nodes affected by constant disturbance such as error measurements, sudden load variations and communication link failure between distributed generator units make the network highly heterogeneous. Firstly, a disturbance observer is established to estimate the disturbance generated from the MG system. Secondly, distributed consensus control law is designed to suppress the disturbances acting on the multi‐agent system. Furthermore, communication delays are explicitly considered in the analysis. The presented control strategy is compared with the existing mainstream algorithms to check the feasibility of the designed control method. The effectiveness of the proposed control law for isolated DC MG system has been validated by MATLAB/Simulink platform using simulation case studies.
Biegebemessungsmodell mit einer geschlossenen und iterativen Lösung für Textilbetonbauteile
Authors: Rempel Sergej , Ricker Marcus , Hegger Josef 
Published: January 2020

AbstractZur Realisierung der bisherigen Bauprojekte mit textiler Bewehrung wurden Zustimmungen im Einzelfall (ZiE) und allgemeine bauaufsichtliche Zulassungen (abZ) benötigt, wofür kosten‐ sowie zeitintensive Tragfähigkeits‐ und Gebrauchstauglichkeitsuntersuchungen durchgeführt werden mussten. Dabei waren insbesondere umfangreiche Untersuchungen zum Nachweis der Biegetragfähigkeit notwendig. Damit in Zukunft die Anzahl der Versuche deutlich reduziert werden kann, ist ein praxistaugliches Biegebemessungsmodell erforderlich. In diesem Beitrag wird ein allgemeingültiges Ingenieurmodell für eine Biegebeanspruchung mit und ohne Normalkrafteinfluss vorgestellt. Hierfür werden für den Beton die bekannten Materialgesetze nach Norm verwendet. Für die textile Bewehrung wird aufbauend auf den bisherigen Untersuchungen ein Vorschlag für den Spannungs‐Dehnungsverlauf gemacht. Das Modell wird durch umfangreiche experimentelle Untersuchungen verifiziert, bei denen die für die Biegebemessung maßgebenden Parameter variiert werden. Abschließend wird aufbauend auf dem Ingenieurmodell ein Bemessungsmodell vorgeschlagen, bei dem zusätzlich Sicherheitsbeiwerte berücksichtigt werden.
Ribosomal RNA Methyltransferase RsmC Moonlights as an RNA Chaperone
Authors: GC Keshav , Gyawali Prabesh , Balci Hamza , Abeysirigunawardena Sanjaya 
Published: January 2020

AbstractRibosomes are ribonucleoprotein particles that are essential for protein biosynthesis in all forms of life. During ribosome biogenesis, transcription, folding, modification, and processing of rRNA are coupled to the assembly of proteins. Various assembly factors are required to synchronize all different processes that occur during ribosome biogenesis. Herein, the RNA chaperone and RNA strand annealing activity of rRNA modification enzyme ribosome small subunit methyltransferase C (RsmC), which modifies guanine to 2‐methylguanosine (m2G) at position 1207 of 16S rRNA (Escherichia coli nucleotide numbering) located at helix 34 (h34), are reported. A 25‐fold increase in the h34 RNA strand annealing rates is observed in the presence of RsmC. Single‐molecule FRET experiments confirmed the ability of protein RsmC to denature a non‐native structure formed by one of the two h34 strands and to form a native‐like duplex. This observed RNA chaperone activity of protein RsmC might play a vital role in the rapid generation of functional ribosomes.
Physicochemical and cooking quality characteristics of South American rice cultivars parboiled at different steaming pressures
Authors: Villanova Franciene Almeida , El Halal Shanise Lisie Mello , Vanier Nathan Levien , Polidoro Edimara , Wang Ya‐Jane , de Oliveira Maurício 
Published: January 2020

AbstractBackground and objectivesSix different long‐slender rice genotypes were studied, being three pure lines (Puita Inta CL, Guri CL, and Irga 424 RI) and three hybrid lines (Titan CL, Lexus CL, and Inov CL). Samples were submitted to parboiling process under different steaming pressures (0.25, 0.50, and 0.75 kgf/cm2).FindingsResults were dependent on genotype instead of line cluster. Intermediate steaming pressures may be useful for five cultivars; Titan CL was the only exception. Titan CL exhibited the lowest amylose content and the highest amylopectin average chain length, gelatinization temperature, and relative crystallinity. At the intermediate parboiling level of 0.50 kgf/cm2, Titan CL exhibited 8.32% of broken grains while the others exhibited values between 2.10% and 4.72%.ConclusionsTitan CL had a more stable crystalline structure that hindered water intake into starch granules. For this reason, Titan CL may be parboiled at severe steaming pressure of 0.75 kgf/cm2 in order to achieve the same extent of gelatinization and physicochemical and cooking quality than the other studied cultivars.Significance and noveltyThe main rice cultivars grown in South America were studied. Results may help rice industries that work with long‐slender high‐to‐intermediate‐amylose rice to select proper parboiling parameters for each cultivar.
Heterostructured manganese catalysts for the selective oxidation of 5‐hydroxymethylfurfural to 2,5‐diformylfuran
Authors: Pal Priyanka , Saravanamurugan Shunmugavel 
Published: January 2020

AbstractA series of manganese oxide catalysts were synthesised in the presence of various precipitants using hydrothermal approach. The manganese oxide synthesised (MnOx−A−U) using manganese acetate tetrahydrate and urea as precursor and precipitant, respectively, was found to be composed of heterostructures of manganese, that is, MnCO3, ϵ‐MnO2 and Mn2O3, and their presence were confirmed by XRD, FTIR and XPS analyses. The catalytic activity of MnOx−A−U towards selective oxidation of HMF to DFF in ethanol afforded 92.0 % conversion along with 88.0 % DFF yield at 120 °C, 30 bar O2, after 4 h of reaction time. Performing HMF oxidation under N2 atmosphere with MnOx−A−U yielded only 15.0 % DFF, revealing that lattice oxygen played a crucial role in the oxidation process, which was confirmed by subjecting the spent catalyst to XPS analysis. Based on the results obtained from XPS analysis, it was speculated that ϵ‐MnO2 and MnCO3 could be the active species which could selectively catalyse the reaction. The MnOx−A−U catalyst was able to recycle for at least three runs with a small loss of activity due to ϵ‐MnO2 content decreased.
Nickel Foam‐Supported Amorphous FeCo(Mn)−O Nanoclusters with Abundant Oxygen Vacancies through Selective Dealloying for Efficient Electrocatalytic Oxygen Evolution
Authors: Wu Shuai‐Na , Qi Yu‐Feng , Wang Qian , Wang Xiu‐Guang , Zhao Xiao‐Jun , Yang En‐Cui 
Published: January 2020

AbstractDeveloping earth‐abundant, cost‐effective and high‐performance electrocatalyst towards the oxygen evolution reaction (OER) is a great challenge for large‐scale hydrogen production from electrochemical water splitting. Nickel‐foam‐supported amorphous hierarchical nanoclusters of metal/metal (hydr)oxides with abundant oxygen defects (FeCo(Mn)−O/NF) were prepared from an FeCoMn/NF precursor through chemical dealloying. The FeCo(Mn)−O/NF electrode exhibits enhanced OER activity in alkaline electrolyte with an overpotential of only 235 mV to drive a current density of 10 mA cm−2, a small Tafel slope of 44.5 mV dec−1 and excellent durability over 100 h. The superior OER performance is attributed to the synergistic effect of abundant oxygen vacancies, hierarchical morphology and amorphous structure, which essentially modulate the electronic structures and create more active sites. These interesting findings highlight the significance of dealloying strategy on the structural defects and improved catalytic performance of the electrocatalysts.
Photosystem I Multilayers within Porous Indium Tin Oxide Cathodes Enhance Mediated Electron Transfer
Authors: Wolfe Kody D. , Dervishogullari Dilek , Stachurski Christopher D. , Passantino Joshua M. , Kane Jennings G. , Cliffel David E. 
Published: January 2020

AbstractInvited for this month's cover picture is the group of Dr. David E. Cliffel from Vanderbilt University (USA). The Cover Picture shows a Photosystem I (PSI) protein complex converting sunlight into chemical energy through an electron transfer reaction with dichlorophenolindophenol (DCPIP). The PSI is entrapped within a macroporous indium tin oxide (ITO) electrode which leverages its high surface area to produce electrical energy from reacted DCPIP. Read the full text of the Article at 10.1002/celc.201901628
Robustness control in bilinear modeling based on maximum correntropy
Authors: Fonseca Diaz Valeria , De Ketelaere Bart , Aernouts Ben , Saeys Wouter 
Published: January 2020

AbstractWe present the development of a bilinear regression model for multivariate calibration on the basis of maximum correntropy criteria (MCC) whose robustness can be easily controlled. MCC regression methods can be more effective when the assumption of normality does not hold or when data are contaminated with outliers. These methods are competitive when the degree of robustness against outliers should be controlled. By controlling the robustness, information from candidate outliers can be partially retained rather than completely included or discarded during calibration. Within the context of bilinear regression models, an MCC approach using statistically inspired modification of the partial least squares (SIMPLS) is proposed, which is named maximum correntropy‐weighted partial least squares (MCW‐PLS). Thanks to the controllable robustness of MCC models, observations are upweighted or downweighted during the calibration process, rendering robust models with soft discrimination of samples. Such a weighting represents an important advantage, especially for cases when samples are not drawn from a normal distribution. Applications to three real case studies are presented. These applications uncovered three main features of MCW‐PLS: robustness control between SIMPLS and robust SIMPLS (RSIMPLS), improvements in prediction performance of bilinear calibration models, and the possibility to detect the most informative samples in a calibration set.
Discrete Supertetrahedral T5 Selenide Clusters and Their Se/S Solid Solutions: Ionic‐Liquid‐Assisted Precursor Route Syntheses and Photocatalytic Properties
Authors: Wang Yanqi , Zhu Zhipeng , Sun Zhaofeng , Hu Qianqian , Li Jianrong , Jiang Jiang , Huang Xiaoying 
Published: January 2020

AbstractAlthough supertetrahedral Tn sulfide clusters (n=2–6) have been extensively explored, the synthesis of Tn selenide clusters with n>4 has not been achieved thus far. Reported here are ionic‐liquid (IL)‐assisted precursor route syntheses, characterizations, and the photocatalytic properties of six new M‐In‐Q (M=Cu or Cd; Q=Se or Se/S) chalcogenide compounds, namely [Bmmim]12Cu5In30Q52Cl3(Im) (Q=Se (T5‐1), Se48.5S3.5 (T5‐2); Bmmim=1‐butyl‐2,3‐dimethylimidazolium, Im=imidazole), [Bmmim]11Cd6In28Q52Cl3(MIm) (Q=Se (T5‐3), Se28.5S23.5 (T5‐4), Se16S36 (T5‐5); MIm=1‐methylimidazole), and [Bmmim]9Cd6In28Se8S44Cl(MIm)3 (T5‐6). The cluster compounds T5‐1 and T5‐3 represent the largest molecular supertetrahedral Tn selenide clusters to date. Under visible‐light illumination, the Cu‐In‐Q compounds showed photocatalytic activity towards the decomposition of crystal violet, whereas the Cd‐In‐Q compounds exhibited good photocatalytic H2 evolution activity. Interestingly, the experimental results show that the photocatalytic performances of the selenide/sulfide solid solutions were significantly better than those of their selenide analogues, for example, the degradation time of the organic dye with T5‐2 was much shorter than that with T5‐1, whereas the photocatalytic H2 evolution efficiencies with T5‐3–T5‐6 improved significantly with increasing sulfur content. This work highlights the significance of IL‐assisted precursor route synthesis and the tuning of photocatalytic properties through the formation of solid solutions.
Evidence for Genuine Bimetallic Frustrated Lewis Pair Activation of Dihydrogen with Gold(I)/Platinum(0) Systems
Authors: Hidalgo Nereida , Moreno Juan José , Pérez‐Jiménez Marina , Maya Celia , López‐Serrano Joaquín , Campos Jesús 
Published: January 2020

AbstractA joint experimental/computational effort to elucidate the mechanism of dihydrogen activation by a gold(I)/platinum(0) metal‐only frustrated Lewis pair (FLP) is described herein. The drastic effects on H2 activation derived from subtle ligand modifications have also been investigated. The importance of the balance between bimetallic adduct formation and complete frustration has been interrogated, providing for the first time evidence for genuine metal‐only FLP reactivity in solution. The origin of a strong inverse kinetic isotopic effect has also been clarified, offering further support for the proposed bimetallic FLP‐type cleavage of dihydrogen.
Pilot Study to Predict Pharmacokinetics of a Therapeutic Gemcitabine Dose From a Microdose
Authors: Van Nuland M. , Rosing H. , Thijssen B. , Burgers J.A. , Huitema A.D.R. , Marchetti S. , Schellens J.H.M. , Beijnen J.H. 
Published: January 2020

AbstractMicrodose studies are exploratory trials to determine early drug pharmacokinetics in humans. In this trial we examined whether the pharmacokinetics of gemcitabine at a therapeutic dose could be predicted from the pharmacokinetics of a microdose. In this prospective, open‐label microdosing study, a gemcitabine microdose (100 µg) was given intravenously to participants on day 1, followed by a therapeutic dose (1250 mg/m2) on day 2. Gemcitabine and its metabolite 2’,2’‐difluorodeoxyuracil (dFdU) were quantified in plasma and intracellularly by using liquid chromatography‐mass spectrometry). Noncompartmental pharmacokinetic analysis was performed. Ten patients participated in this study. The mean area under the plasma concentration‐time curve (AUC0‐8) of gemcitabine after microdosing was 0.00074 h·mg/L and after therapeutic dosing was 16 h·mg/L. The mean AUC0‐8 of dFdU following the microdose and therapeutic dose were 0.022 h·mg/L and 169 h·mg/L, respectively. Exposure to gemcitabine after the therapeutic dose was within 2‐fold of the exposure following a microdose, when linearly extrapolated to 1250 mg/m2. However, the shape of the concentration‐time curve was different, as reflected by poor scalability in volume of distribution (939 L versus 222 L). Furthermore, intracellularly phosphorylated gemcitabine and phosphorylated dFdU levels could not be predicted from the microdose. The AUC0‐8 of gemcitabine at therapeutic dose was accurately predicted by the pharmacokinetics of a microdose, when linearly extrapolated to 1250 mg/m2. Volume of distribution, elimination rate constant, and intracellular pharmacokinetics of the therapeutic dose could not be predicted from the microdose, which demonstrates limitations of the microdose approach in this case.