bluuebunny/crossref_metadata_2025 huggingface dataset:
A Transient‐Directing‐Group Strategy Enables Enantioselective Reductive Heck Hydroarylation of Alkenes
Authors: Oxtoby Lucas J. , Li Zi‐Qi , Tran Van T. , Erbay Tuğçe G. , Deng Ruohan , Liu Peng , Engle Keary M.
Published: March 2020

Metal‐coordinating directing groups have seen extensive use in the field of transition‐metal‐catalyzed alkene functionalization; however, their waste‐generating installation and removal steps limit the efficiency and practicality of reactions that rely on their use. Inspired by developments in asymmetric organocatalysis, where reactions rely on reversible covalent interactions between an organic substrate and a chiral mediator, we have developed a transient‐directing‐group approach to reductive Heck hydroarylation of alkenyl benzaldehyde substrates that proceeds under mild conditions. Highly stereoselective migratory insertion is facilitated by in situ formation of an imine from catalytic amounts of a commercially available amino acid additive. Computational studies reveal an unusual mode of enantioinduction by the remote chiral center in the transient directing group.
Künstliche Enzymkaskaden angetrieben mittels elektrischer Energie
Authors: Al‐Shameri Ammar , Petrich Marie‐Christine , junge Puring Kai , Apfel Ulf‐Peter , Nestl Bettina M. , Lauterbach Lars
Published: March 2020

Wir haben eine skalierbare Plattform entwickelt, bei der die Elektrolyse für eine synthetische Enzymkaskade in einem Durchflussreaktor eingesetzt wird. Sowohl H2 als auch O2 wurden durch Elektrolyse hergestellt und über eine gasdurchlässige Membran in das Durchflusssystem überführt. Die Membran ermöglichte die Trennung des Elektrolyten von den Biokatalysatoren im Durchflusssystem, wobei H2 und O2 als Elektronenvermittler für die Biokatalysatoren dienten. Darüber hinaus demonstrierten wir die Herstellung methylierter N‐Heterozyklen aus Diaminen mit bis zu einer 99 % Produktbildung sowie einer ausgezeichneten regioselektiven Markierung mit stabilen Isotopen. Diese entwickelte Plattform kann für ein breites Spektrum von Oxidoreduktasen eingesetzt werden, um elektrische Energie für die Synthese von Feinchemikalien zu nutzen.
Iridium‐katalysierte C‐H‐Borylierung von Heteroarenen: Eine Balance zwischen sterischer and elektronischer Regiokontrolle
Authors: Wright Jay S. , Scott Peter J. H. , Steel Patrick G.
Published: March 2020

Die Ir‐katalysierte Borylierung aromatischer C‐H‐Bindungen ist heute die bevorzugte Methode zur Synthese aromatischer Organoborverbindungen. Sie ist hocheffizient, toleriert vielzählige Substituenten und kann bei carbo‐ wie auch heterocyclischen Substraten angewendet werden. Die Regioselektivität der C‐H‐Aktivierung beruht hauptsächlich auf sterischen Überlegungen, und in den letzten Jahren gab es erhebliche Bemühungen, selektivere Prozesse für weniger eingeschränkte Substrate zu entwickeln. Allerdings haben sich viele Arbeiten auf benzoide Arene konzentriert, wogegen Heteroarene begehrte und anspruchsvolle Substrate bleiben, in denen die Reaktivität und Regioselektivität von der Stellung und/oder Art der Heteroatome abhängt. Dieser Aufsatz gibt einen Überblick über die Borylierung von Heteroarenen und konzentriert sich auf den Einfluss sterischer und elektronischer Effekte auf das regiochemische Ergebnis. Außerdem soll er durch Verknüpfung mit dem derzeitigen mechanistischen Verständnis einen Einblick in die momentanen Möglichkeiten und Richtungen für weitere notwendige Entwicklungen bieten.
Constructing a Super‐Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries
Authors: Yang Huijun , Chang Zhi , Qiao Yu , Deng Han , Mu Xiaowei , He Ping , Zhou Haoshen
Published: March 2020

Rechargeable aqueous zinc batteries (RAZB) have been re‐evaluated because of the superiority in addressing safety and cost concerns. Nonetheless, the limited lifespan arising from dendritic electrodeposition of metallic Zn hinders their further development. Herein, a metal–organic framework (MOF) was constructed as front surface layer to maintain a super‐saturated electrolyte layer on the Zn anode. Raman spectroscopy indicated that the highly coordinated ion complexes migrating through the MOF channels were different from the solvation structure in bulk electrolyte. Benefiting from the unique super‐saturated front surface, symmetric Zn cells survived up to 3000 hours at 0.5 mA cm−2, near 55‐times that of bare Zn anodes. Moreover, aqueous MnO2–Zn batteries delivered a reversible capacity of 180.3 mAh g−1and maintained a high capacity retention of 88.9 % after 600 cycles with MnO2mass loading up to 4.2 mg cm−2.
Messungen an μm‐Proben – ein alternativer Weg zur Untersuchung intrinsischer Eigenschaften von Festkörper‐Materialien am Beispiel des Halbleiters TaGeIr
Authors: Antonyshyn I. , Wagner F. R. , Bobnar M. , Sichevych O. , Burkhardt U. , Schmidt M. , König M. , Poeppelmeier K. , Mackenzie A. P. , Svanidze E. , Grin Yu.
Published: March 2020

Eine korrekte Materialuntersuchung wird häufig durch mikro‐ und makroskopische Einschlüsse von Sekundärphasen verhindert. In einigen Fällen können aufwändige Syntheseverfahren dieses Problem lösen; in anderen gelingt jedoch keine Herstellung einphasiger Materialien. Ein Beispiel ist TaGeIr, dessen Eigenschaften stark probenabhängig sind. Eine Erklärung dafür ist das Auftreten mehrerer Phasen, die den elektronischen Transport im Material beeinflussen. Dieser Einfluss der Minoritätsphasen konnte vermieden werden, indem mithilfe eines fokussierten Ionenstrahls μm‐große Messkörper präpariert wurden, die nur eine einzelne Phase – TaGeIr – enthielten. Wir liefern hier einen Nachweis der intrinsischen Halbleitereigenschaften von TaGeIr als Beispiel für die selektive Präparation einphasiger Messkörper. Die Verwendung von μm‐großen Messkörpern bietet einen Zugang zu intrinsischen Eigenschaften von Verbindungen, die nicht einphasig synthetisierbar sind, und reduziert dadurch teure und zeitaufwändige Bemühungen zur Materialsynthese.
Electrochemical Phase Evolution of Metal‐Based Pre‐Catalysts for High‐Rate Polysulfide Conversion
Authors: Zhao Meng , Peng Hong‐Jie , Li Bo‐Quan , Chen Xiao , Xie Jin , Liu Xinyan , Zhang Qiang , Huang Jia‐Qi
Published: March 2020

In situ evolution of electrocatalysts is of paramount importance in defining catalytic reactions. Catalysts for aprotic electrochemistry such as lithium–sulfur (Li‐S) batteries are the cornerstone to enhance intrinsically sluggish reaction kinetics but the true active phases are often controversial. Herein, we reveal the electrochemical phase evolution of metal‐based pre‐catalysts (Co4N) in working Li‐S batteries that renders highly active electrocatalysts (CoSx). Electrochemical cycling induces the transformation from single‐crystalline Co4N to polycrystalline CoSx that are rich in active sites. This transformation propels all‐phase polysulfide‐involving reactions. Consequently, Co4N enables stable operation of high‐rate (10 C, 16.7 mA cm−2) and electrolyte‐starved (4.7 μL mgS−1) Li‐S batteries. The general concept of electrochemically induced sulfurization is verified by thermodynamic energetics for most of low‐valence metal compounds.
Micro‐Scale Device—An Alternative Route for Studying the Intrinsic Properties of Solid‐State Materials: The Case of Semiconducting TaGeIr
Authors: Antonyshyn I. , Wagner F. R. , Bobnar M. , Sichevych O. , Burkhardt U. , Schmidt M. , König M. , Poeppelmeier K. , Mackenzie A. P. , Svanidze E. , Grin Yu.
Published: March 2020

An efficient application of a material is only possible if we know its physical and chemical properties, which is frequently obstructed by the presence of micro‐ or macroscopic inclusions of secondary phases. While sometimes a sophisticated synthesis route can address this issue, often obtaining pure material is not possible. One example is TaGeIr, which has highly sample‐dependent properties resulting from the presence of several impurity phases, which influence electronic transport in the material. The effect of these minority phases was avoided by manufacturing, with the help of focused‐ion‐beam, a μm‐scale device containing only one phase—TaGeIr. This work provides evidence for intrinsic semiconducting behavior of TaGeIr and serves as an example of selective single‐domain device manufacturing. This approach gives a unique access to the properties of compounds that cannot be synthesized in single‐phase form, sparing costly and time‐consuming synthesis efforts.
A data‐driven approach for flow corrosion characteristic parameters prediction in an air cooler
Authors: Jin Haozhe , Wu Xiangyao , Liu Xiaofei , Zhang Lin , Gu Yong , Quan Jianxun
Published: March 2020

A data‐driven soft measurement method based on a multiunit back propagation neural network (MBPNN) is presented in this study. This model aims to estimate the characteristic parameters that can reflect the flow corrosion of the reactor effluent air cooler (REAC). Flow corrosion failure during the hydrogenation process presents a serious concern to the petrochemical industry. In this paper, a safety evaluation of flow corrosion failure for a petrochemical diesel hydrogenation unit is first carried out. During the investigation, it is found that there is a risk of NH4Cl crystallization at around 187°C. Then, considering flow‐induced corrosion and ammonium salt deposition, main characteristic parameters are determined, including NH4Cl crystallization temperature (TC), air cooler tube bundle minimum and maximum flow rate (VminandVmax), air cooler inlet liquid water content (CW), and NH4HS concentration (CA). Finally, the data‐driven model based on a multiunit back propagation neural network (MBPNN) is constructed. An improved particle swarm optimization (PSO) approach is employed to initialize the main parameters of the model. Compared with a multioutput back propagation neural network (BPNN) model and MBPNN model without an optimization algorithm, the presented data‐driven model is proved to have high accuracy, a fast convergence rate, and high reliability.
Absorption of CO2 in aqueous blend of methyldiethanolamine and arginine
Authors: Talkhan Ahmed Gomaa , Benamor Abdelbaki , Nasser Mustafa , El‐Naas Muftah H. , El‐Tayeb Sayed Ahmad , El‐Marsafy Sahar
Published: March 2020

The objective of this research is to study for the first time the effect of adding l‐arginine (Arg) amino acid on the solubility of carbon dioxide in aqueous solution of N‐methyldiethanolamine (MDEA). The study was carried out at different mixing ratios of MDEA and Arg at a total concentration of 2 moles per litre. The CO2 partial pressure varied from about 10 to 100 kPa, and the temperature varied from 293 K to 323 K. The experimental results showed improved solubility of CO2 with the addition of Arg at CO2 partial pressures below 20 kPa. However, for CO2 partial pressure of above 20 kPa, the addition of Arg caused a decrease in the solubility of CO2. The obtained loading data were correlated using a semiempirical (SE) vapour liquid equilibrium (VLE) model with an average absolute deviation (AAD) less than 4.1% between the predicted and the experimental values. An estimation of the heat of CO2 absorption in the solution was obtained using an analytical expression for ΔHabs derived from the SE model and was found to be in the range of 29‐ to 40‐kJ/mole CO2. From the finding of this work, it is anticipated that the studied novel blended solvent will effectively reduce CO2 capture costs as the CO2 content of most gas streams is less than 20% by volume, which is specifically true for natural gas and a large number of industrial flue gas streams.
Adhesion between ethylene‐propylene‐diene monomer and thermoplastics in two‐component injection molding: Effect of dicumylperoxide as curing agent
Authors: Laing Brittany , De Keyzer Jozefien , Seveno David , Van Bael Albert
Published: March 2020

Strong adhesion at the interface is an important aspect in two‐component (2K) injection molding. It was therefore investigated whether dicumylperoxide (DCP) as curing agent in ethylene‐propylene‐diene monomer (EPDM) could stimulate interdiffusion and/or induce chemical bonding with thermoplastics. EPDM mixtures containing DCP concentrations between 2 to 8 parts per hundred rubber (phr) were combined with polar and non‐polar thermoplastics. Changes in EPDM physico‐mechanical bulk properties were analyzed, and the adhesion was evaluated by high temperature contact angle measurements and tensile testing. Results showed that DCP concentration did not influence EPDM‐thermoplastic compatibility. However, EPDM adhesion with polyethylene (PE) did improve when using up to 6 phr DCP (57% adhesion) as crosslinking is promoted. While with polypropylene (PP), adhesion linearly decreased (from 55% to 35% adhesion) with higher DCP concentrations due to prevailing scission reactions. Adhesion through chemical bonding with acrylonitrile‐butadiene‐styrene (ABS) caused better adhesion at 4 phr (43% adhesion) compared to polycarbonate (PC) at 4 phr (13% adhesion) where only limited interdiffusion occurs. Thus, selecting the optimal DCP concentration is highly important to boost adhesion between EPDM and thermoplastics. Furthermore, at these optimal DCP concentrations, physico‐mechanical properties require consideration as these properties were significantly affected.
Cellulosenanocrystals‐organicmontmorillonite nanohybrid material by electrostatic self‐assembly
Authors: Liu Hao , He Hui , Huang Bai
Published: March 2020

The hybridization based on various nanoparticles is an emerging technological field, involving the synergistic hybrid assembly of nanoparticles. In order to broaden the application of existing nanomaterials such as cellulose nanocrystals (CNC) and montmorillonite (MMT), a novel CNC–organic MMT (OMMT) nanohybrid material was constructed by electrostatic self‐assembly. Morphology observations showed that one‐dimensional needle‐like CNC were adsorbed on the surface of two‐dimensional flake‐like OMMT, thereby forming a three‐dimensional nanohybrid. In the nanohybrid, CNC and OMMT still maintained their original chemical structures. Zeta potential results indicated that there was a strong electrostatic adsorption between CNC and OMMT. Based on this, the lamellar structure of OMMT can hide sulfate groups on the CNC surface and had a shielding effect on heat transfer, thereby evidently improving the thermal stability of the nanohybrid. The nanohybrid with unique nanostructure is expected to achieve synergistic effects in polymer nanocomposites, which may provide a promising strategy for the fabrication of high‐performance polymer nanocomposites.
Tuning Magnetic Anisotropy in a Class of Co(II) Bis(hexafluoroacetylacetonate) Complexes
Authors: Huang Xing‐Cai , Li Jia‐Xin , Chen Yong‐Zhi , Wang Wen‐Yan , Xu Rui , Tao Jin‐Xia , Shao Dong , Zhang Yi‐Quan
Published: March 2020

Tuning the magnetic anisotropy of metal ions remains highly interesting in the design of improved single‐molecule magnets (SMMs). We herein report synthetic, structural, magnetic, and computational studies of four mononuclear CoII complexes, namely [Co(hfac)2(MeCN)2] (1), [Co(hfac)2(Spy)2] (2), [Co(hfac)2(MBIm)2] (3), and [Co(hfac)2(DMF)2] (4) (MeCN=acetonitrile, hfac=hexafluoroacetylacetone, Spy=4‐styrylpyridine, MbIm=5,6‐dimethylbenzimidazole, DMF=N,N‐dimethylformamide), with distorted octahedral geometry constructed from hexafluoroacetylacetone (hfac) and various axial ligands. By a building block approach, complexes 2–4 were synthesized by recrystallization of the starting material of 1 from various ligands containing solution. Magnetic and theoretical studies reveal that 1–4 possess large positive D values and relative small E parameters, indicating easy‐plane magnetic anisotropy with significant rhombic anisotropy in 1–4. Dynamic alternative current (ac) magnetic susceptibility measurements indicate that these complexes exhibit slow magnetic relaxation under external fields, suggesting field‐induced single‐ion magnets (SIMs) of 1–4. These results provide a promising platform to achieve fine tuning of magnetic anisotropy through varying the axial ligands based on Co(II) bis(hexafluoroacetylacetonate) complexes.
Money does not stink: Using unpleasant odors as stimulus material changes risky decision making
Authors: von Helversen Bettina , Coppin Géraldine , Scheibehenne Benjamin
Published: March 2020

Odors are strong elicitors of affect, and they play an important role in guiding human behavior, such as avoiding fire or spoiled food. However, little is known about how risky decision making changes when stimuli are olfactory. We investigated this question in an experimental study of risky decision making with unpleasant odors and monetary losses in a fully incentivized task with real outcomes. Odor and monetary decisions were matched so that monetary losses corresponded to the amount of money participants were willing to pay to avoid smelling an odor. Hierarchical Bayesian analyses using prospect theory show that participants were less sensitive to probabilities when gambling with odors than when gambling with money. These results highlight the importance of taking the sensory modality into account when studying risky decision making.
Hydrothermal synthesis of carbon dots and their application for detection of chlorogenic acid
Authors: Han Zhu , He Li , Pan Shuang , Liu Hui , Hu Xiaoli
Published: March 2020

A novel and sensitive fluorescence analysis platform was constructed for the detection of chlorogenic acid (CGA) using carbon dots (C‐dots) with prominent sensitivity and selectivity. Excitation‐dependent emission fluorescence C‐dots were fabricated using citric acid and l‐histidine as precursors through an efficient one‐step hydrothermal treatment. The maximum excitation and emission wavelength of the as‐synthesized C‐dots were 340 nm and 414 nm, respectively. Moreover, the as‐prepared C‐dots displayed excellent water solubility and good photostability. The fluorescence quantum yield of the as‐prepared C‐dots was measured to be about 22% using quinine sulfate as the reference. Furthermore, the obtained C‐dots were applied to the detection of CGA accompanied with a wide linear range from 1.53 μmol L−1 to 80.0 μmol L−1 as well as a limit detection of 0.46 μmol L−1. More importantly, the proposed fluorescence method was successfully used to analyse CGA in coffee and honeysuckle.
Prediagnostic adult body mass index change and esophageal adenocarcinoma survival
Authors: Loehrer Elizabeth A. , Giovannucci Edward L. , Betensky Rebecca A. , Shafer Andrea , Christiani David C.
Published: March 2020

Background

We examined whether body mass index (BMI) changes in adulthood, prior to disease onset, are associated with overall survival among esophageal adenocarcinoma patients.

Methods

We included 285 histologically confirmed patients with a complete baseline BMI questionnaire. Using extended Cox regression models, we obtained adjusted hazard ratios (HRs) for the associations between overall survival and BMI at diagnosis, BMI 6 months before diagnosis, self‐reported average adult BMI, and ΔBMI (BMI 6 months before diagnosis minus average adult BMI), categorized into tertiles <0 kg/m2 (BMI loss), ≥0 and <1.25 kg/m2 (stable BMI), and ≥1.25 kg/m2 (BMI gain). We also assessed interaction between ΔBMI and average adult BMI (≥ kg/m2 versus <27.5 kg/m2) with overall survival.

Results

Body mass index at diagnosis >25 and <35 kg/m2 was associated with better overall survival. Compared to patients with stable BMI in adulthood, patients who gained BMI throughout adulthood had 1.68 times the all‐cause hazard of death (95% CI: 1.17‐2.43; P < .01), independent of diagnosis BMI and percent weight loss 6 months before diagnosis. Compared to patients with average adult BMI < 27.5 who maintained stable adult BMI, patients with average adult BMI ≥ 27.5 kg/m2 who gained BMI had the worst survival (HR = 3.05; 95% CI 1.62‐5.72; P < .01).

Conclusion

Body mass index gain in adulthood is associated with poor overall survival, and maintaining a normal body weight throughout adulthood is associated with the best overall survival among esophageal adenocarcinoma patients, independent of BMI at diagnosis.
The Influence of Competing tRNA Abundance on Translation: Quantifying the Efficiency of Sense Codon Reassignment at Rarely Used Codons
Authors: Schwark David G. , Schmitt Margaret A. , Biddle Wil , Fisk John D.
Published: March 2020

A quantitative understanding of how system composition and molecular properties conspire to determine the fidelity of translation is lacking. Our strategy directs an orthogonal tRNA to directly compete against endogenous tRNAs to decode individual targeted codons in a GFP reporter. Sets of directed sense codon reassignment measurements allow the isolation of particular factors contributing to translational fidelity. In this work, we isolated the effect of tRNA concentration on translational fidelity by evaluating reassignment of the 15 least commonly employed E. coli sense codons. Eight of the rarely used codons are reassigned with greater than 20 % efficiency. Both tRNA abundance and codon demand moderately inversely correlate with reassignment efficiency. Furthermore, the reassignment of rarely used codons does not appear to confer a fitness advantage relative to reassignment of other codons. These direct competition experiments also map potential targets for genetic code expansion. The isoleucine AUA codon is particularly attractive for the incorporation of noncanonical amino acids, with a nonoptimized reassignment efficiency of nearly 70 %.
Sanger Gap Sequencing for Genetic Alphabet Expansion of DNA
Authors: Kimoto Michiko , Soh Si Hui Gabriella , Hirao Ichiro
Published: March 2020

Genetic alphabet expansion technology, creating new replicable and functional DNA molecules with unnatural base pairs (UBPs), is the novel promising research area of xenobiology. Recently, this technology has rapidly advanced, resulting in the need for a sequencing method for DNA molecules containing UBPs. However, all of the conventional sequencing methods, such as Sanger methods, are for four‐letter DNA molecules. Here, we present an improved Sanger sequencing method (Sanger gap sequencing) for DNAs containing our UBP, Ds‐Px, which appears as gaps in the sequencing peak patterns. By improving the sequencing reaction for efficient Ds‐Px pairing and using modified Px substrates, we have developed a sequencing method with increased processivity and clear gap patterns for multiple Ds‐Px pairs in various sequence contexts. This method is useful for UBP applications such as high‐affinity DNA aptamer generation and semisynthetic organism creation involving UBPs. In addition, through this research, we found that the side chains of UBs greatly affect the efficiency of UB pairings in replication, thus suggesting further development of UBPs.
Pb2+ as a Substrate and a Cofactor of a Porphyrin Metalation DNAzyme
Authors: Yang Hualin , Peng Dong , Zhou Yu , Liu Juewen
Published: March 2020

We herein report a DNAzyme named T30695 (sequence: (G3T)4) that can catalyze Zn2+ insertion into three different porphyrins in the presence of Pb2+ as a cofactor. Meanwhile, T30695 with Pb2+ alone was found to cause a shift in both the fluorescence and UV‐vis spectra of protoporphyrin IX (PPIX), thus suggesting that metalation of Pb2+ was also achieved at room temperature. From kinetic measurements, the reaction required two Pb2+ ions; this is consistent with one being a cofactor and the other being a substrate. No previous reports inserted Pb2+ into porphyrins by using DNAzymes or protein‐based enzymes. This reaction was most significantly inhibited in the presence of K+ followed by Na+ and Li+, suggesting the importance of the Pb2+‐stabilized G‐quadruplex. When Pb2+ is inserted into PPIX, its emission blue shifts from 635 to 590 nm, thus allowing simple ratiometric fluorescent sensing with a detection limit of 1.2 nM Pb2+.
Measuring Enzymatic Activities with Nanopores
Authors: Sheng Yingying , Zhang Shouwen , Liu Lei , Wu Hai‐Chen
Published: March 2020

Nanopores have become powerful and versatile tools for measuring single molecules since their emergence in the mid‐1990s. They can be used to sense a wide variety of analytes including metal ions, small organic molecules, DNA/RNA, proteins, etc. to monitor chemical reactions, and to sequence DNA. Recently, enzymes have been studied by using nanopore technologies. In this Minireview, we highlight recent efforts in developing nanopore enzymology and categorize the related work into three groups: 1) measuring enzymatic activities with nanopore‐enzyme hybrids; 2) measuring enzymatic activities through sensing their catalytic products with nanopores; 3) the use of enzymes for DNA sequencing and DNA/protein translocation. At the end, we discuss the challenges and opportunities in nanopore enzymology.
Recent Development of Photothermal Agents (PTAs) Based on Small Organic Molecular Dyes
Authors: Lv Shibo , Miao Yuyang , Liu Dapeng , Song Fengling
Published: March 2020

Photothermal therapy (PTT) has attracted great attention due to its noninvasive and effective use against cancer. Various photothermal agents (PTAs) including organic and inorganic PTAs have been developed in the last decades. Organic PTAs based on small‐molecule dyes exhibit great potential for future clinical applications considering their good biocompatibility and easy chemical modification or functionalization. In this review, we discuss the recent progress of organic PTAs based on small‐molecule dyes for enhanced PTT. We summarize the strategies to improve the light penetration of PTAs, methods to enhance their photothermal conversion efficiency, how to optimize PTAs’ delivery into deep tumors, and how to resist photobleaching under repeated laser irradiation. We hope that this review can rouse the interest of researchers in the field of PTAs based on small‐molecule dyes and help them to fabricate next‐generation PTAs for noninvasive cancer therapy.
Stability, Structure and Reconstruction of 1H‐Edges in MoS2
Authors: Sayed‐Ahmad‐Baraza Yuman , Ewels Christopher P.
Published: March 2020

Density functional studies of the edges of single‐layer 1H‐MoS2 are presented. This phase presents a rich variability of edges that can influence the morphology and properties of MoS2 nano‐objects, play an important role in industrial chemical processes, and find future applications in energy storage, electronics and spintronics. The so‐called Mo‐100 %S edges vertical S‐dimers were confirmed to be stable, however the authors also identified a family of metastable edges combining Mo atoms linked by two‐electron donor symmetrical disulfide ligands and four‐electron donor unsymmetrical disulfide ligands. These may be entropically favored, potentially stabilizing them at high temperatures as a “liquid edge” phase. For Mo‐50 %S edges, S‐bridge structures with 3× periodicity along the edge are the most stable, compatible with a Peierls’ distortion arising from the d‐bands of the edge Mo atoms. An additional explanation for this periodicity is proposed through the formation of 3‐center bonds.
Hetero Diels–Alder Reactions with a Dicationic Urea Azine Derived Azo Dienophile and Their Use for the Synthesis of an Electron‐Rich Pentacene
Authors: Werr Marco , Kaifer Elisabeth , Himmel Hans‐Jörg
Published: March 2020

Herein, the first hetero Diels–Alder (DA) reactions with a stable, dicationic urea azine derived azo dienophile, synthesized by two‐electron oxidation of a neutral urea azine are reported. Several charged DA products were synthesized in good yield and fully characterized. The DA adduct of anthracene is in thermal equilibrium with the reactants at room temperature, and the reaction enthalpy and entropy were determined from the temperature‐dependent equilibrium constant. Furthermore, base addition to solutions of the pentacene DA product led to deprotonation, cleavage of the N−N bond, and formation of an electron‐rich 6,13‐bisguanidinyl‐substituted pentacene. The redox and optical properties of this new pentacene derivative were studied. Furthermore, the dication resulting from its two‐electron oxidation was synthesized and fully characterized. The results disclose a new elegant route to electron‐rich pentacene derivatives.
Electro‐Olefination—A Catalyst Free Stereoconvergent Strategy for the Functionalization of Alkenes
Authors: Baumann Andreas N. , Music Arif , Dechent Jonas , Müller Nicolas , Jagau Thomas C. , Didier Dorian
Published: March 2020

Conventional methods carrying out C(sp2)−C(sp2) bond formations are typically mediated by transition‐metal‐based catalysts. Herein, we conceptualize a complementary avenue to access such bonds by exploiting the potential of electrochemistry in combination with organoboron chemistry. We demonstrate a transition metal catalyst‐free electrocoupling between (hetero)aryls and alkenes through readily available alkenyl‐tri(hetero)aryl borate salts (ATBs) in a stereoconvergent fashion. This unprecedented transformation was investigated theoretically and experimentally and led to a library of functionalized alkenes. The concept was then carried further and applied to the synthesis of the natural product pinosylvin and the derivatization of the steroidal dehydroepiandrosterone (DHEA) scaffold.
Polymer Entrapment Flash Pyrolysis for the Preparation of Nanoscale Iridium‐Free Oxygen Evolution Electrocatalysts
Authors: Shih Pei‐Chieh , Zhang Cheng , Raheja Harshit , Sun Cheng‐Jun , Yang Hong
Published: March 2020

This paper describes the use of a new polymer entrapment flash pyrolysis (PEFP) method for making nanoscale yttrium ruthenate (Y2Ru2O7‐δ) electrocatalysts. This approach effectively reduced the synthesis temperature of phase‐pure pyrochlore catalysts from 1000 °C to 550 °C, and greatly suppressed the sintering of catalyst particles. The supported nanocrystalline Y2Ru2O7‐δ catalysts showed enhanced activity towards oxygen evolution reaction (OER) in acidic electrolyte and were stable at 1.50 V for the comparative study (>20 h) under the current density of 10 mA/cm2geo in chronopotentiometry testing. This is equivalent to an overpotential value of 270 mV, about half of that of the reference IrO2 catalyst. X‐ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) analysis showed that the high‐surface‐area Y2Ru2O7‐δ catalyst had an oxygen‐deficient structure. This study provides a route to the synthesis of fine ceramic (or oxide)‐based electrocatalysts for making high‐performing electrocatalysts.
Pharmacokinetics and Immunogenicity of ASP0113 in CMV‐Seronegative Dialysis Patients and CMV‐Seronegative and ‐Seropositive Healthy Subjects
Authors: Bonate Peter L. , Van Sant Charles , Cho Kathy , Zook Erin C. , Smith Larry R. , Boutsaboualoy Sou , Ye Ming , Wang Xuegong , Wu Ruishan , Koester Anne , Rammelsberg Diane , Goldwater Ronald , Marbury Thomas C.
Published: March 2020

Cytomegalovirus (CMV) infection causes significant morbidity and mortality in immunocompromised transplant patients. ASP0113, a first‐in‐class DNA vaccine containing plasmids encoding CMV phosphoprotein 65 and glycoprotein B (gB), was evaluated in a phase 1b, subject‐blinded study in CMV‐seropositive (n = 13) and CMV‐seronegative (n = 12) healthy and CMV‐seronegative dialysis subjects (n = 12) randomized to ASP0113 or placebo. End points included pharmacokinetics, anti‐gB antibody levels, phosphoprotein 65–specific T‐cell responses measured by ex vivo enzyme‐linked immune absorbent spot (ELISpot) assay and 10‐day cultured ELISpot and Stat T‐cell activation assays, and safety. ASP0113 concentrations peaked at 2‐10 and 24‐48 hours; the pharmacokinetics were similar across groups. No group demonstrated significant anti‐gB antibody responses. T‐cell responder rates in the cultured ELISpot assay were 8/12 (66.7%, 95%CI 35% to 90%) and 4/12 (33.3%, 95%CI 10% to 65%) in CMV‐seronegative healthy subjects and dialysis patients, respectively, whereas ex vivo ELISpot assay response rates were 4/11 (36.4%, 95%CI 11% to 69%) and 0/12, respectively. Responses peaked at week 27, with lower magnitude observed in CMV‐seronegative dialysis patients versus CMV‐seronegative healthy subjects. No serious adverse events occurred; the most common adverse event in ASP0113‐vaccinated patients was injection‐site pain (64.9%). Some CMV‐seronegative healthy subjects and dialysis patients had T‐cell responses; no humoral responses were detected.
On the Stability of Interactions between Pairs of Anions – Complexes of MCl3− (M=Be, Mg, Ca, Sr, Ba) with Pyridine and CN−
Authors: Zierkiewicz Wiktor , Wysokiński Rafał , Michalczyk Mariusz , Scheiner Steve
Published: March 2020

The ability of the central M atom of the MCl3− anion, with M=Be, Mg, Ca, Sr, Ba, to engage in a noncovalent bond with an approaching nucleophile is gauged by ab initio methods. The N atom of pyridine forms a M⋅⋅⋅N bond with an interaction energy between 12 and 21 kcal mol−1, even though the π‐hole above the M atom is not necessarily positive in sign. Despite a strong Coulombic repulsion between two anions, CN− is also able to approach the M atom so as to engage in a metastable complex that is higher in energy than the individual anions. The energy barrier separating this complex from its constituent anion pair is roughly 20 kcal mol−1. Despite the endothermic formation reaction energy of the CN−⋅⋅⋅MCl3− complex, the electron topology signals a strong interaction, more so than in pyridine⋅⋅⋅MCl3− with its exothermic binding energy. The dianionic complex is held together largely on the strength of interorbital interactions, thereby overcoming a repulsive electrostatic component. The latter is partially alleviated by the pyramidalization of the MCl3 unit which makes its π‐hole more positive. The complex sinks below the separate monomers in energy when the system is immersed in an aqueous medium, with a binding energy that varies from as much as 20 kcal mol−1 for Be down to 1.2 kcal mol−1 for Ba.
Copper(II) Dicyanamide Complexes with N‐Substituted Tetrazole Ligands – Energetic Coordination Polymers with Moderate Sensitivities
Authors: Wurzenberger Maximilian H. H. , Lechner Jasmin T. , Stierstorfer Jörg
Published: March 2020

Following the useful concept of energetic coordination compounds (ECC), copper(II) dicyanamide was used as a building block for the synthesis of eight new complexes. As ligands, six different N‐substituted tetrazoles were applied, leading to the formation of high‐nitrogen containing complexes. The obtained compounds were characterized in detail by single crystal as well as powder XRD, IR, EA, DTA, and TGA. In addition, the sensitivities towards impact and friction were determined with BAM standard techniques as well as the sensitivity towards electrostatic discharges. All compounds show moderate sensitivities (IS>6, FS>80 N) and energetic properties but differ in their polymeric structures forming polymeric chains or layers up to 3D networks.
Sustainable Lignin‐Derived Cross‐Linked Graft Polymers as Electrolyte and Binder Materials for Lithium Metal Batteries
Authors: Jeong Daun , Shim Jimin , Shin Huiseob , Lee Jong‐Chan
Published: March 2020

This study concerns the development of a well‐defined synthetic route to obtain lignin‐derived multifunctional graft polymers by simple chemical modification and atom‐transfer radical polymerization. By grafting ion‐conducting and cross‐linkable moieties onto the lignin, star‐shaped functional polymers are prepared. Upon cross‐linking under ultraviolet light irradiation, the resulting polymer network exhibits mechanical stability even at high temperature, whereas the chain mobility is maintained despite the cross‐linked structure. Their use as solid polymer electrolytes (SPEs) and binders for all‐solid‐state lithium metal batteries (LMBs) is also evaluated. The lignin‐derived graft polymers provide a facile ion conduction pathway and also efficiently suppress lithium dendrite growth during cycling, thereby attaining excellent cycling performance for the LMB cell compared to that with a conventional liquid electrolyte–Celgard system.
Ambient Ammonia Electrosynthesis: Current Status, Challenges, and Perspectives
Authors: Lv Xian‐Wei , Weng Chen‐Chen , Yuan Zhong‐Yong
Published: March 2020

Ammonia (NH3) electrosynthesis from atmospheric nitrogen (N2) and water is emerging as a promising alternative to the energy‐intensive Haber–Bosch process; however, such a process is difficult to perform due to the inherent inertness of N2 molecules together with low solubility in aqueous solutions. Although many active electrocatalysts have been used to electrocatalyze the N2 reduction reaction (NRR), unsatisfactory NH3 yields and lower Faraday efficiency are still far from practical industrial production, and thus, considerable research efforts are being devoted to address these problems. Nevertheless, most reports still mainly focus on the preparation of electrocatalysts and largely ignore a summary of optimization–modification strategies for the NRR. In this review, a general introduction to the NRR mechanism is presented to provide a reasonable guide for the design of highly active catalysts. Then, four categories of NRR electrocatalysts, according to chemical compositions, are surveyed, as well as several strategies for promoting the catalytic activity and efficiency. Later, strategies for developing efficient N2 fixation systems are discussed. Finally, current challenges and future perspectives in the context of the NRR are highlighted. This review sheds some light on the development of highly efficient catalytic systems for NH3 synthesis and stimulates research interests in the unexplored, but promising, research field of the NRR.
Survivorship of geographic Pomacea canaliculata populations in responses to cold acclimation
Authors: Qin Zhong , Wu Rui Shan , Zhang Jiaen , Deng Zhi Xin , Zhang Chun Xia , Guo Jing
Published: March 2020

Pomacea canaliculata, a freshwater snail from South America, has rapidly established natural populations from south to north subtropical region in China, since its original introductions in the 1980s. Low temperature in winter is a limiting factor in the geographic expansion and successfully establishment for apple snail populations. There have been some studies on population level of low temperature tolerance for P. canaliculata, yet little is quantified about its life‐history traits in responses to cold temperatures. Whether these responses vary with the acclimation location is also unclear. We investigated the survivorship and longevity of P. canaliculata in responses to cold temperatures and examine whether these responses vary with the location and snail size. We hypothesized that survival of the snails depends on their shell height and the level of low temperature, and P. canaliculata population from the mid-subtropical zone may exhibit the highest viability over the cold thermal range.

We sampled P. canaliculata populations from five latitude and longitude ranges of subtropical China: Guangzhou population in southernmost (SM‐GZ), three populations of Yingtan (MR‐YT), Ningbo (MR‐NB), Ya'an (MR‐YA) in midrange, and Huanggang population in northernmost (NM‐HG) subtropical zone. For each P. canaliculata population, survival and longevity at six cold acclimation temperature levels (12, 9, 6, 3, 0, and −3°C) were quantified, and the effects of location and shell height were examined.

The MR‐YA population from mid-subtropical zone of China exhibited the highest survival rate and prolonged survival time regardless of the temperature acclimation treatments, whereas the SM‐GZ population from southern subtropical was the most sensitive to cold temperatures, particular temperatures below 9°C. No individuals of the SM‐GZ population could survive after stressed for 30 days (3°C), 5 days (0°C) and 2 days (−3°C), respectively. For each experimental P. canaliculata population held at 3, 0, and −3°C, individuals with intermediate shell height of 15.0–25.0 mm had significantly higher survivals.

The results highlight a request of a more thorough investigation on acclimation responses in each of the life table demographic parameters for P. canaliculata, and pose the question of whether natural selection or some genetic changes may have facilitated adaptation in invasive locations.
Increased resting heart rate and prognosis in treatment‐naïve unselected cancer patients: results from a prospective observational study
Authors: Anker Markus S. , Frey Maria K. , Goliasch Georg , Bartko Philipp E. , Prausmüller Suriya , Gisslinger Heinz , Kornek Gabriela , Strunk Guido , Raderer Markus , Zielinski Christoph , Hülsmann Martin , Pavo Noemi
Published: March 2020

Aims

Cancer patients suffer from impaired cardiovascular function. Elevated resting heart rate (RHR) has been identified as a marker for increased long‐term mortality in cancer patients prior to the receipt of anticancer treatment. We aimed to establish whether RHR is associated with survival in treatment‐naïve cancer patients.

Methods and results

This prospective study enrolled 548 unselected treatment‐naïve cancer patients between 2011 and 2013. The median age of the cohort was 62 years; 40.9% were male and 32.7% had metastatic disease. Median RHR was 72 b.p.m. Most patients were in sinus rhythm (n = 507, 92.5%). Clinical heart failure was noted in 37 (6.8%) patients. RHR was not related to cancer stage (P = 0.504). Patients in the highest RHR tertile had higher levels of high‐sensitivity troponin (P = 0.003) and N‐terminal pro‐B‐type natriuretic peptide (P = 0.039). During a median follow‐up of 25 months (interquartile range: 16–32 months; range: 0–40 months), 185 (33.8%) patients died from any cause [1‐year‐mortality: 17%, 95% confidence interval (CI) 13–20%]. In univariate survival analysis, RHR predicted all‐cause mortality [crude hazard ratio (HR) for a 5 b.p.m. increase in RHR: 1.09, 95% CI 1.04–1.15; P < 0.001], and remained significantly associated with outcome after adjustment for age, gender, tumour entity, tumour stage, cardiac status and haemoglobin (adjusted HR for a 5 b.p.m. increase in RHR: 1.10, 95% CI 1.04–1.16; P < 0.001). There was no significant impact of metastatic/non‐metastatic disease state on the predictive value of RHR (P = 0.433 for interaction). In subgroup analyses, the strongest associations for RHR with mortality were observed in lung (crude HR 1.14; P = 0.007) and gastrointestinal (crude HR 1.31; P < 0.001) cancer.

Conclusions

Treatment‐naïve cancer patients with higher RHRs display higher levels of cardiovascular biomarkers. RHR was independently associated with all‐cause mortality, especially in lung and gastrointestinal cancers. Elevated RHR and cardiovascular biomarkers may represent early signs of incipient cardiac dysfunction.
Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds
Authors: O'Brien Nathan J. , Kano Naokazu , Havare Nizam , Uematsu Ryohei , Ramozzi Romain , Morokuma Keiji
Published: March 2020

The isolation and reactivities of two pentacoordinated phosphorus–tetracoordinated boron bonded compounds were explored. A highly Lewis acidic boron reagent and electron‐withdrawing ligand system were required to form the pentacoordinated phosphorus state of the P–B bond. The first compound, a phosphoranyl‐trihydroborate, gave a THF stabilised phosphoranyl‐borane intermediate upon a single hydride abstraction in THF. This compound could undergo a unique rearrangement, which involved a two‐fold ring expansion, to give a fused bicyclic compound or it could act as a mono‐hydroboration reagent. The hydroboration reactivity of the intermediate was found to be higher towards alkynes vs. alkenes, with good to moderate regioselectivity towards the terminal carbon. The second compound, a phosphoranyl‐triarylborate, was found to have different reactivity as it was highly stable towards acids and bases. This is thought to be due to the large bulk around the P–B bond as shown in the crystal structure.
Similarity and Competition between Biginelli and Hantzsch Reactions: an Opportunity for Modern Medicinal Chemistry
Authors: Costanzo Paola , Nardi Monica , Oliverio Manuela
Published: March 2020

Similarity and competition between multicomponent reactions with similar mechanisms and leading to similar scaffolds can be a useful tool for medicinal chemistry. In this review, we have summarized the studies disclosing the mechanism of such competition between the Biginelli and Hantzsch reactions. We focused our attention in particular on those studies exploiting similarity and competition as an opportunity to switch from one reaction to another, by simply changing the reaction conditions, thus opening the possibility to obtain, using the same experimental setup, molecular libraries of both 3,4‐dihydropyrimidin‐2‐(1H)‐ones (DHPM) and 1,4‐dihydropyridines (1,4‐DHP) scaffolds. The aim of this review is to encourage further exploitation of such synthetic strategy as a tool for enhancing the chemical space in medicinal chemistry.
Syntheses of Phosphonium Salts from Phosphines and Carbenium: Efficient CO2 Fixation and Phase‐Transfer Catalysts
Authors: Shaikh Aslam C. , Veleta José M. , Bloch Jan , Goodman Hannah J. , Gianetti Thomas L.
Published: March 2020

A new library of phosphonium salts has been synthesized from the reaction of tris‐(2,6‐dimethoxyphenyl)carbenium with different phosphines. The resultant phosphoninum salts work as efficient phase‐transfer catalysts for the alkylation of 1,3‐dicarbonyl compounds. One compound, a bifunctional phosphonium salt prepared from tris‐(2,6‐dimethoxyphenyl)carbenium and an aminophosphine, was also found to be an efficient catalyst for CO2 fixation reactions with epoxides under mild conditions.
A Novel Approach to Highly Substituted β‐Carbolines via Reductive Ring Transformation of 2‐Acyl‐3‐isoxazolylindoles
Authors: Kamlah Alexandra , Bracher Franz
Published: March 2020

We have worked out a new approach to 1,3,4‐trisubstituted β‐carbolines of pharmaceutical interest. As central building blocks we used 2‐acylindoles, which are readily available from indole‐2‐Weinreb amides. Bromination at C‐3, followed by Suzuki–Miyaura cross‐coupling with isoxazole‐4‐boronates gives 2‐acyl‐3‐isoxazolylindoles. Ring closure to the β‐carbolines was accomplished by reductive ring transformation upon catalytic hydrogenation in the presence of Cs2CO3.
Carbon Nanostructured Screen‐printed Electrodes Modified with CuO/Glucose Oxidase/Maltase/SiO2 Composite Film for Maltose Determination
Authors: Kornii Anastasiia , Saska Vita , Lisnyak Vladyslav V. , Tananaiko Oksana
Published: March 2020

A sensitive voltammetric method was developed to determine maltose in beverage products using a carbon nanostructured screen‐printed electrode modified with CuO/glucose oxidase/maltase/SiO2 biocomposite film. Adding CuO particles was done to possess catalytic activity toward hydrogen peroxide. Electrode modified by glucose oxidase and maltase shows a good response to maltose. A well‐defined reduction peak was registered at the potential of −0.55 V (vs. Ag/AgCl) which intensity increases linearly with the concentration of maltose ranging from 0.01 to 0.1 mmol L−1. The calculated limit of detection was 0.005 mmol L−1. Tested on the beer samples, the developed CuO/glucose oxidase/maltase/SiO2 biocomposite film covered carbon nanostructured screen‐printed electrode is showed to be a prospective sensitive element of the third generation biosensor for maltose.