bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmon‐Induced Hot Carrier Separation across Dual Interface in Gold–Nickel Phosphide Heterojunction for Photocatalytic Water Splitting
Authors: Mondal Indranil , Lee Hyunhwa , Kim Heeyoung , Park Jeong Young
Published: December 2019

Precise control of the topology of metal nanocrystals and appropriate modulation of the metal–semiconductor heterostructure is an important way to understand the relationship between structure and material properties for plasmon‐induced solar‐to‐chemical energy conversion. Here, a bottom‐up wet chemical approach to synthesize Au/Ni2P heterostructures via Pt‐catalyzed quasi‐epitaxial overgrowth of Ni on Au nanorods (NR) is presented. The structural motif of the Ni2P is controlled using the aspect ratio of the Au NR and the effective micelle concentration of the C16TAB capping agent. Highly ordered Au/Pt/Ni2P nanostructures are employed as the photoelectrocatalytic anode system for water splitting. Electrochemical and ultrafast absorption spectroscopy characterization indicates that the structural motif of the Ni2P (controlled by the outer‐shell deposition of Ni) helps to manipulate hot electron transfer during surface plasmon decay. With optimized Ni2P thickness, Pt‐tipped Au NR with an aspect ratio of 5.2 exhibits a geometric current density of 10 mA cm−2 with an overpotential of 140 mV. The photoanode displays unprecedented long‐term stability with continuous chronoamperometric performance of 50 h at an input potential of 1.5 V with over 30 days. This work provides definitive guidance for designing plasmonic–catalytic nanomaterials for enhanced solar‐to‐chemical energy conversion.
Charge‐Transfer Exciton Manipulation Based on Hydrogen Bond for Efficient White Thermally Activated Delayed Fluorescence
Authors: Sun Jianan , Zhang Jing , Liang Qianqian , Wei Ying , Duan Chunbo , Han Chunmiao , Xu Hui
Published: December 2019

Despite the success of thermally activated delayed fluorescence (TADF) emitters in monochromatic organic light‐emitting diodes (OLED), only few efficient full‐TADF white OLEDs (WOLED) are reported because of the challenge in rational exciton allocation between blue and other color emitters. Herein, it is demonstrated that the appropriate exciton delocalization in blue TADF matrixes can simultaneously support the sufficient blue emission and the energy loss–free charge and exciton transfer to yellow TADF emitters. Through introducing steric hindrance–modulated intermolecular hydrogen bond networks, a fluorinated carbazole‐phosphine oxide hybrid realizes the balance of exciton localization and delocalization, giving rise to state‐of‐the‐art external quantum efficiency beyond 20% from its simple trilayer full‐TADF WOLEDs, accompanied by excellent spectral stability. The correlation between the efficiencies of the blue TADF matrixes and their intermolecular interactions reveals that the exciton delocalization is crucial for the exciton allocation optimization in multicomponent emission systems.
Fabrication of Bio‐Inspired 2D MOFs/PAA Hybrid Membrane for Asymmetric Ion Transport
Authors: Wang Chen , Liu Fei‐Fei , Tan Zheng , Chen Yu‐Ming , Hu Wen‐Chao , Xia Xing‐Hua
Published: December 2019

Biological ion channels are known as membrane proteins which can turn on and off under environmental stimulus to regulate ion transport and energy conversion. Rapid progress made in biological ion channels provides inspiration for developing artificial nanochannels to mimic the structures and functions of ion transport systems and energy conversion in biological ion channels. Due to the advantages of abundant pore channels, metal–organic frameworks (MOFs) have become competitive materials to control the nanofluidic transport. Herein, a facile in situ synthesis method is developed to prepare hybrid nanochannels constructed by 2D MOFs and porous anodic aluminum (PAA). The introduction of asymmetries in the chemical composition and surface charge properties gives the hybrid outstanding ion current rectification properties and excellent ion selectivity. A power density of 1.6 W m−2 is achieved by integrating it into a salinity‐gradient‐driven device. With advantages of facile fabrication method and high ion selectivity, the prepared 2D MOFs/PAA hybrid membrane offers a promising candidate for power conversion and water desalination.
Hierarchical NiS@CoS with Controllable Core‐Shell Structure by Two‐Step Strategy for Supercapacitor Electrodes
Authors: Miao Yidong , Zhang Xuping , Zhan Jiang , Sui Yanwei , Qi Jiqiu , Wei Fuxiang , Meng Qingkun , He Yezeng , Ren Yaojian , Zhan Zhenzhen , Sun Zhi
Published: December 2019

Constructing hierarchical core‐shell configuration from well‐known metal sulfides is one way to further tune and utilize unique species. Herein, a novel core‐shell structure is developed based on CoS deposited on NiS nanosheets, which involves hydrothermal and electrodeposition method. The micromorphology of the composite electrode can be optimized by adjusting the cycles of electrodeposition. Taking advantages of the highly conductive, open framework of the core‐shell nanolayer, the 5‐NiS@CoS electrode shows a specific capacitance of 1210 F g−1 at a current density of 1 A g−1 (retaining 82% from 1 to 10 A g−1, while NiS substrate is only 39%). The specific capacitance retention rate is 80.94% at 10 A g−1 after 2000 cycles (NiS substrate is 59.6%). Moreover, NiS@CoS//AC asymmetric supercapacitor device delivers an energy density of 24.1 Wh kg−1 at a power density of 752.15 W kg−1 and remarkable stability (over 80% retention after 5000 cycles). This work may prompt the exploration of the synthesis of inexpensive compounds incorporating highly reactive components for supercapacitors.
Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies
Authors: Liang Longwei , Zhang Wenheng , Zhao Fei , Denis Dienguila Kionga , Zaman Fakhr uz , Hou Linrui , Yuan Changzhou
Published: December 2019

Nickel‐rich layered transition‐metal oxides with high‐capacity and high‐power capabilities are established as the principal cathode candidates for next‐generation lithium‐ion batteries. However, several intractable issues such as the poor thermal stability and rapid capacity fade as well as the air‐sensitivity particularly for the Ni content over 80% have seriously restricted their broadly practical applications. The properties and nature of the stable surface/interface, where the Li+ shuttles back and forth between the cathode and electrolyte, play a significant role in their ultimate lithium‐storage performance and industrial processability. Thus, tremendous efforts are made to in‐depth understanding of the essential origins of surface/interface structure degradation and efficient surface modification methodologies are intensively explored. The purpose of the contribution is first to provide a comprehensive review of the up‐to‐date mechanisms proposed to rationally elucidate the surface/interface behaviors, and then, focus on recent developed strategies to optimize the surface/interface structure and chemistry including synthetic condition regulation, surface doping, surface coating, dual doping‐coating modification, and concentration‐gradient structure as well as electrolyte additives. Finally, the perspective on future research trends and feasible approaches toward advanced Ni‐rich cathodes with stable surface/interface is presented briefly.
Supply Fundamentals and Grain Futures Price Movements
Authors: Karali Berna , Irwin Scott H. , Isengildina‐Massa Olga
Published: December 2019

A long‐standing puzzle in commodity markets is the low explanatory power of supply and demand fundamentals for explaining the variability of prices in these markets. We apply an instrumental variable correction for measurement errors to investigate how noise in the surprise component of USDA Crop Production reports affects estimated price responses in corn, soybeans, and wheat futures markets from 1970 to 2016. Our findings demonstrate that after correcting for measurement error in market surprises, the explanatory power of our models increases about threefold and often exceeds 70%. This is compelling evidence that fundamental supply news play an important role in explaining grain futures price movements.
Disentangling phylogenetic and functional components of shape variation among shoot apical meristems of a wide range of herbaceous angiosperms
Authors: Schnablová Renáta , Neustupa Jiří , Woodard Kateřina , Klimešová Jitka , Herben Tomáš
Published: December 2019

Premise

The shoot apical meristem (SAM) is the basic determinant of plant body organization, but interspecific variation inSAMshape and its relationship to stem and leaf morphological traits is not well known. Here we tested the hypothesis that differentSAMshapes are associated with specific shoot traits of the plant body and examined the phylogenetic conservatism of these relationships.

Methods

We used geometric morphometrics ofSAMoutlines for a phylogenetically representative set of 110 herbaceous angiosperms and examined their relationship to a number of shoot traits.

Results

We found large variations inSAMshapes across angiosperm lineages, but covering only a subset of geometrically possible shapes. Part of this variation was allometric (due toSAMsize), but the dominant shape variation (dome‐shaped vs. flat surface) was size‐independent and strongly phylogenetically conserved.SAMshapes were largely independent of their cell size and therefore of the number of cells involved. Different patterns in shape variation of outer and innerSAMboundaries were associated with stem thickness, leaf area, and leafiness of the stem.

Conclusions

The findings show that geometric interdependence of meristem zones gives rise to correlations among organ numbers, sizes, and their proportions. Phylogenetic conservatism in these correlations indicates conservatism in regulatory processes that underlie the correlations, or the individual traits, that give rise to plant architecture.
Tunable Periodically Ordered Mesoporosity in Palladium Membranes Enables Exceptional Enhancement of Intrinsic Electrocatalytic Activity for Formic Acid Oxidation
Authors: Ding Jia , Liu Zhi , Liu Xiaorui , Liu Bin , Liu Jie , Deng Yida , Han Xiaopeng , Hu Wenbin , Zhong Cheng
Published: December 2019

Developing superior electrocatalysts for formic acid oxidation (FAO) is the most crucial step in commercializing direct formic acid fuel cells. Herein, we electrodeposited palladium membranes with periodically ordered mesoporosity obtained by asymmetrically replicating the bicontinuous cubic phase structure of a lyotropic liquid‐crystal template. The Pd membrane with the largest periodicity and highest degree of order delivered up to 90.5 m2 g−1 of electrochemical active surface area and 3.34 A mg−1 electrocatalysis capability towards FAO, 3.8 and 7.8 times the values of the commercial Pd/C catalyst, respectively. By controlling the temperature and potential of the electrodeposition procedure, the periodicity area and order degree of the mesoporosity are highly tunable. These Pd membranes gave prototype formic acid fueled cells with 4.3 and 2.4 times the maximum current and power density of the commercial Pd/C catalyst.
Ribosomal Incorporation of Aromatic Oligoamides as Peptide Sidechain Appendages
Authors: Tsiamantas Christos , Kwon Sunbum , Rogers Joseph M. , Douat Céline , Huc Ivan , Suga Hiroaki
Published: December 2019

Derivatives of 4‐aminomethyl‐l‐phenylalanine with aromatic oligoamide foldamers as sidechain appendages were successfully charged on tRNA by means of flexizymes. Their subsequent incorporation both at the C‐terminus of, and within, peptide sequences by the ribosome, was demonstrated. These results expand the registry of chemical structures tolerated by the ribosome to sidechains significantly larger and more structurally defined than previously demonstrated.
Access to Hydroxy‐Functionalized Polypropylene through Coordination Polymerization
Authors: Zhong Yuanhao , Douair Iskander , Wang Tiantian , Wu Chunji , Maron Laurent , Cui Dongmei
Published: December 2019

Preparation of polyethylenes containing hydroxy groups has been already industrialized through radical copolymerization under harsh conditions followed by alcoholysis. By contrast, hydroxy‐functionalized polypropylene has proven a rather challenging goal in polymer science. Propylene can't be polymerized through a radical mechanism, and its coordination copolymerization with polar monomers is frustrated by catalyst poisoning. Herein, we report a new strategy to reach this target. The coordination polymerization of allenes by rare‐earth‐metal precursors affords pure 1,2‐regulated polyallenes, which are facilely transformed into poly(allyl alcohol) analogues by subsequent hydroboration/oxidation. Strikingly, the copolymerization of allenes and propylene gives unprecedented hydroxy‐functionalized polypropylene after post‐polymerization modification. Mechanistic elucidation by DFT simulation suggests kinetic rather than thermodynamic control.
Exploiting the Bulk Photovoltaic Effect in a 2D Trilayered Hybrid Ferroelectric for Highly Sensitive Polarized Light Detection
Authors: Peng Yu , Liu Xitao , Sun Zhihua , Ji Chengmin , Li Lina , Wu Zhenyue , Wang Sasa , Yao Yunpeng , Hong Maochun , Luo Junhua
Published: December 2019

Polarized light detection is attracting increasing attention for its wide applications ranging from optical switches to high‐resolution photodetectors. Two‐dimensional (2D) hybrid perovskite‐type ferroelectrics combining inherent light polarization dependence of bulk photovoltaic effect (BPVE) with excellent semiconducting performance present significant possibilities. Now, the BPVE‐driven highly sensitive polarized light detection in a 2D trilayered hybrid perovskite ferroelectric, (allyammonium)2(ethylammonium)2Pb3Br10 (1), is presented. It shows a superior BPVE with near‐band gap photovoltage of ca. 2.5 V and high on/off switching ratio of current (ca. 104). Driven by the superior BPVE, 1 exhibits highly sensitive polarized light detection with a polarization ratio as high as ca. 15, which is far more beyond than those of structural anisotropy‐based monocomponent devices. This is the first realization of BPVE‐driven polarized light detection in hybrid perovskite ferroelectrics.
Synthese von gem‐Difluorolefinen durch C‐H‐Funktionalisierung und β‐Fluorideliminierungsreaktionen
Authors: Yang Zhen , Möller Mieke , Koenigs Rene M.
Published: December 2019

In diesem Artikel berichten wir über die palladiumkatalysierte Reaktion von Indolen mit fluorierten Diazoalkanen. Dieser Ansatz bietet nun erstmalig eine einfache Methode für die effiziente Synthese von gem‐Difluorolefinen unter milden Reaktionsbedingungen mit fluorierten Diazoalkane. Diese reagieren mit N‐alkylierten Indolen in einer C‐H‐Funktionalisierung gefolgt von einer β‐Fluorideliminierungsreaktion. Die entsprechenden Cyclopropanierungsprodukte werden erhalten, wenn in dieser Reaktion N‐arylierte Indole eingesetzt werden. In mechanistischen Studien können wir zeigen, dass eine β‐Fluorideliminierung einen zentralen Reaktionsschritt darstellt. Diese Methode ist damit ein neuartiges Konzept, das den einfachen und direkten Transfer einer 1‐Aryl‐(2,2‐difluorvinyl)‐Gruppe für die Synthese von gem‐Difluorolefinen ermöglicht.
Exploiting a C–N Bond Forming Cytochrome P450 Monooxygenase for C–S Bond Formation
Authors: Morita Iori , Mori Takahiro , Mitsuhashi Takaaki , Hoshino Shotaro , Taniguchi Yoshimasa , Kikuchi Takashi , Nagae Kei , Nasu Norihiro , Fujita Makoto , Ohwada Tomohiko , Abe Ikuro
Published: December 2019

C–S bond formation reactions are widely distributed in the biosynthesis of biologically active molecules, and thus have received much attention over the past decades. Herein, we report intramolecular C–S bond formation by a P450 monooxygenase, TleB, which normally catalyzes a C−N bond formation in teleocidin biosynthesis. Based on the proposed reaction mechanism of TleB, a thiol‐substituted substrate analogue was synthesized and tested in the enzyme reaction, which afforded the unprecedented sulfur‐containing thio‐indolactam V, in addition to an unusual indole‐fused 6/5/8‐tricyclic product whose structure was determined by the crystalline sponge method. Interestingly, conformational analysis revealed that the SOFA conformation is stable in thio‐indolactam V, in sharp contrast to the major TWIST form in indolactam V, resulting in differences in their biological activities.
Direct C−H Bond Borylation of (Hetero)Arenes: Evolution from Noble Metal to Metal Free
Authors: Li Yahui , Wu Xiao‐Feng
Published: December 2019

Organoboron compounds are among the most versatile and useful building blocks in modern synthetic chemistry. The past decades have seen impressive developments in the direct C−H bond borylation of (hetero)arenes in which the applied catalysts are shifting from noble metals to metal‐free systems. This Highlight gives a brief summary on this evolution and focuses on recent elegant work in this field.
Synthesis of gem‐Difluoro Olefins through C−H Functionalization and β‐fluoride Elimination Reactions
Authors: Yang Zhen , Möller Mieke , Koenigs Rene M.
Published: December 2019

A palladium catalyzed C−H functionalization and consecutive β‐fluoride elimination reaction between indole heterocycles and fluorinated diazoalkanes is reported. This approach provides for the first time a facile method for the rapid synthesis of gem‐difluoro olefins using fluorinated diazoalkanes under mild reaction conditions. Cyclopropanation products were obtained when N‐arylated rather than N‐alkylated indoles were applied in this reaction. Mechanistic studies reveal the importance of the β‐fluoride elimination step in this transformation. This method presents a new concept for the simple and direct transfer of a 1‐aryl‐(2,2‐difluorovinyl) group to access gem‐difluoro olefins.
Fibroin‐functionalized magnetic carbon nanotube as a green support for anchoring silver nanoparticles as a biocatalyst for A3 coupling reaction
Authors: Akbarzadeh Parisa , Koukabi Nadiya
Published: December 2019

Novel and powerful fibroin‐functionalized magnetic carbon nanotube–supported silver nanoparticles (CNT–Fe3O4–fibroin–Ag) were successfully synthesized as a nontoxic and inexpensive biocatalyst. The structure of the organic–inorganic hybrid bionanocomposite was characterized by various techniques such as Fourier transform infrared spectroscopy, thermogravimetric analysis, energy‐dispersive X‐ray, field emission‐scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, vibrating sample magnetometry, atomic absorption spectroscopy, and inductively coupled plasma‐optical emission spectrometry. Then, the catalytic activity of synthesized bionanocomposite was evaluated in the three‐component A3 coupling reaction under solvent‐free conditions with good to excellent yields. Several propargylamine derivatives were synthesized by the reaction of different aldehydes with amines and phenylacetylene. Biodegradability, biocompatibility, availability, easy synthesis, high stability, high‐throughput, cost‐effectiveness, and efficient magnetic separation are some advantages of this catalyst that make it economically justified and sustainable. Moreover, the catalyst can be recycled for several runs without appreciable loss in its catalytic activity.
Air‐stable zirconium (IV)‐salophen perfluorooctanesulfonate as a highly efficient and reusable catalyst for the synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones under solvent‐free conditions
Authors: Li Ningbo , Wang Yijun , Liu Feijun , Zhao Xin , Xu Xinhua , An Quan , Yun Keming
Published: December 2019

An air‐stable complex of zirconium (IV)‐salophen perfluorooctanesulfonate (1) was successfully synthesized by reacting Zr (salphen)Cl2and C8F17SO3Ag. Complex1was characterized and studied by different techniques (NMR, IR, HRMS, TG‐DSC, conductivity and acidity measurements), and was found to be air‐stable, water tolerant, thermally stable and strongly Lewis‐acidic. Complex1exhibited high catalytic efficiency for the synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones via the Biginelli reaction of aldehydes, 1,3‐dicarbonyl compounds and urea/thiourea under solvent‐free conditions. Furthermore, complex1could be reused 5 times with minimal changes in catalytic efficiency. Compared with previously reported methods, the important features of this protocol are the solvent‐free conditions, the short reaction times, the wide substrate compatibility, the high efficiency and the good reusability.
Synthesis and investigation of desalinating, antibacterial, and mechanical properties of tetraethylorthosilicate crosslinked chitosan/polyethylene glycol (PEG‐300) membranes for reverse osmosis
Authors: Raza Arsalan , Kayani Anum , Sabir Aneela , Ahmad Adnan , Hussain Tajamal , Raza Muhammad Hamid , Bano Shehr , Islam Atif , Khan Rafi Ullah
Published: December 2019

Solution casting method was used to synthesize chitosan (CS)‐based membranes for reverse osmosis (RO) using PEG‐300 and tetraethylorthosilicate as a crosslinker. Their salt rejection (%) and permeate flux (mL/h.m2) was measured by using lab scale RO plant. FTIR spectroscopy reveals interactions between CS and PEG by shifting of OH peak from 3237 cm−1 to lower wavenumber in modified membranes. SEM results showed pores in modified membranes while pure CS membranes had uniform nonporous and dense microstructure. DMA results demonstrated that the addition of PEG lowers the Tg value up to 6.5%. Water content of membranes increases up to 82.63% as the amount of PEG increases owing to its hydrophilic nature. The bacterial killing ability showed that the modified membranes possess good antibacterial activity against Escherichia coli in comparison to the control film. The permeation results revealed that salt rejection and flux of the modified membranes increased up 60% and 86.36 mL/h.m2, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48870.
The Effect of Stereoscopic Augmented Reality Visualization on Learning Anatomy and the Modifying Effect of Visual‐Spatial Abilities: A Double‐Center Randomized Controlled Trial
Authors: Bogomolova Katerina , van der Ham Ineke J.M. , Dankbaar Mary E.W. , van den Broek Walter W. , Hovius Steven E.R. , van der Hage Jos A. , Hierck Beerend P.
Published: December 2019

Monoscopically projected three‐dimensional (3D) visualization technology may have significant disadvantages for students with lower visual‐spatial abilities despite its overall effectiveness in teaching anatomy. Previous research suggests that stereopsis may facilitate a better comprehension of anatomical knowledge. This study evaluated the educational effectiveness of stereoscopic augmented reality (AR) visualization and the modifying effect of visual‐spatial abilities on learning. In a double‐center randomized controlled trial, first‐ and second‐year (bio)medical undergraduates studied lower limb anatomy with stereoscopic 3D AR model (n = 20), monoscopic 3D desktop model (n = 20), or two‐dimensional (2D) anatomical atlas (n = 18). Visual‐spatial abilities were tested with Mental Rotation Test (MRT), Paper Folding Test (PFT), and Mechanical Reasoning (MR) Test. Anatomical knowledge was assessed by the validated 30‐item paper posttest. The overall posttest scores in the stereoscopic 3D AR group (47.8%) were similar to those in the monoscopic 3D desktop group (38.5%; P = 0.240) and the 2D anatomical atlas group (50.9%; P = 1.00). When stratified by visual‐spatial abilities test scores, students with lower MRT scores achieved higher posttest scores in the stereoscopic 3D AR group (49.2%) as compared to the monoscopic 3D desktop group (33.4%; P = 0.015) and similar to the scores in the 2D group (46.4%; P = 0.99). Participants with higher MRT scores performed equally well in all conditions. It is instrumental to consider an aptitude–treatment interaction caused by visual‐spatial abilities when designing research into 3D learning. Further research is needed to identify contributing features and the most effective way of introducing this technology into current educational programs.
DyF3: An Efficient Electrocatalyst for N2 Fixation to NH3 under Ambient Conditions
Authors: Li Yuanfang , Li Tingshuai , Zhu Xiaojuan , Alshehri Abdulmohsen Ali , Alzahrani Khalid Ahmed , Lu Siyu , Sun Xuping
Published: December 2019

NH3 synthesis by the Haber–Bosch method is regarded as the dominant method in industry. Such a process is energy‐intensive, accompanied by a large amount of CO2 emission. Electrocatalytic N2 reduction is a sustainable avenue for NH3 production at ambient conditions. However, it needs a catalyst to boost the N2 reduction reaction. Here, we demonstrate that DyF3 is an efficient electrocatalyst. In 0.1 m Na2SO4, DyF3 attains a large NH3 yield of 10.9 μg h−1 mg−1cat. at −0.45 V vs. the reversible hydrogen electrode, with the corresponding Faradaic efficiency of 8.8 %. Furthermore, this catalyst exhibits high electrochemical stability.
Photoswitchable Adhesives Using Azobenzene‐Containing Materials
Authors: Xu Guofeng , Li Shuxiu , Liu Chengwei , Wu Si
Published: December 2019

Photoinduced reversible solid‐to‐liquid transitions of azobenzene‐containing materials can control adhesion. Photoswitchable adhesives based on azobenzene‐containing small molecules and polymers are under intense investigation. The melting points or glass transition temperatures of such azobenzene‐containing materials intransandcisforms are above and below room temperature, respectively. Photoswitching of these materials results in reversibletrans‐cisisomerization and solid‐to‐liquid transitions. The solidtransazobenzene‐containing materials have strong adhesion and the liquidcisazobenzene‐containing materials have weaker adhesion. In this Minireview, we introduce adhesives based on azobenzene‐containing small molecules and polymers. The remaining challenges and perspectives in the field of photoswitchable adhesives using azobenzene‐containing materials are also discussed.
Design and Synthesis of ZnII‐Coordination Polymers Anchored with NSAIDs: Metallovesicle Formation and Multi‐drug Delivery
Authors: Bera Sourabh , Chowdhury Abhinanda , Sarkar Koushik , Dastidar Parthasarathi
Published: December 2019

A series of coordination polymers synthesized from a bis‐pyridyl linker, namely 4,4′‐azopyridine (L), selected non‐steroidal‐anti‐inflammatory drugs (NSAIDs), namely diclofenac (Dic), ibuprofen (Ibu), flurbiprofen (Flu), mefenamic acid (Mefe), and naproxen (Nap), and Zn(NO3)2 were characterized by single crystal X‐ray diffraction. One of the coordination polymers, namely CP3 derived from Flu, was able to form metallovesicles in DMSO, DMSO/H2O and DMSO/DMEM (biological media) as revealed by TEM, AFM and DLS. Metallovesicle formation by CP3 was further supported by loading a fluorescent dye, namely calcein, as well as an anti‐cancer drug, doxorubicin hydrochloride (DOX), as revealed by UV‐vis and emission spectra, and fluorescence microscopy. DOX‐loaded metallovesicles of CP3 (DOX@CP3‐vesicle) could be delivered in vitro to a highly aggressive human breast cancer cell line, namely MDA‐MB‐231, as revealed by MTT and cell migration assays, and also cell imaging performed under laser scanning confocal microscope (LSCM). Thus, a proof of concept for developing a multi‐drug delivery system derived from a metallovesicle for delivering an anti‐cancer drug to cancer cells is demonstrated for the first time.
Structure Identification of Novel Compounds Using Simple IR, 1H, and 13C NMR Spectroscopy and Computational Tools
Authors: Cho Kwang‐Hwi , Hansen Poul Erik
Published: December 2019

A simple method is suggested to identify the structure of novel compounds with basic IR, 1H, and 13C nuclear magnetic resonance (NMR) spectroscopy and computational tools. With the molecular formula obtained from high‐resolution mass spectrometry, all possible isomers are calculated. The absence or presence of particular functional groups which were inferred from IR, 1H, and 13C NMR and DEPT spectra are used to sort all the possible isomers using SMARTS code and RDKit. Then, the final structure(s) are identified by comparing the correlation between Quantum mechanically calculated 13C NMR chemical shielding constants and experimental 13C chemical shifts of molecules in consideration. We have applied this protocol to five natural compounds, the number of heavy atoms ranging from 11 to 15, and correctly identified the structures of all test cases. The limitations and further consideration are discussed.
Development and validation of a sensitive and specific LC–MS/MS cocktail assay for CYP450 enzymes: Application to study the effect of catechin on rat hepatic CYP activity
Authors: Nguyen Van , Espiritu Michael , Elbarbry Fawzy
Published: December 2019

A sensitive and specific liquid chromatography tandem mass spectrometric (LC–MS/MS) method that enables the simultaneous quantification of probe substrates and metabolites of cytochrome P450 (CYP) enzymes was developed and validated. These substrates (metabolites)—coumarin (7‐hydroxycoumarin), tolbutamide (4‐hydroxytolbutamide), S‐mephenytoin (4‐hydroxymephenytoin), dextromethorphan (dextrorphan), and testosterone (6β‐hydroxytestosterone)—were utilized as markers for the activities of the major human CYP enzymes CYP2A6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, respectively. Analytes were separated on Kinetex C18 column (2.1 × 50 mm, 5 μm) using a binary gradient mobile phase of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Metabolites were detected and quantified by MS using multiple reaction monitoring at m/z 163 → 107.2 for 7‐hydroxycoumarin, m/z 235 → 150.1 for 4‐hydroxymephenytoin, m/z 287 → 171 for 4‐hydroxytolbutamide, m/z 258 → 157.1 for dextrorphan, m/z 305 → 269 for 6β‐hydroxytestosterone, and m/z 237 → 194 for the internal standard. The assay exhibited good linearity over a range of 10–500 ng/mL with acceptable accuracy and precision criteria.

As a proof of concept, the developed cocktail assay was successfully used to examine the potential impact of catechin on the activity of the major rat liver CYP enzymes.
Stepwise Construction of Disulfides in Peptides
Authors: He Rongjun , Pan Jia , Mayer John P. , Liu Fa
Published: December 2019

The disulfide bond plays an important role in biological systems. It defines global conformation, and ultimately the biological activity and stability of the peptide or protein. It is frequently present, singly or multiply, in biologically important peptide hormones and toxins. Numerous disulfide‐containing peptides have been approved by the regulatory agencies as marketed drugs. Chemical synthesis is one of the prerequisite tools needed to gain deep insights into the structure–function relationships of these biomolecules. Along with the development of solid‐phase peptide synthesis, a number of methods of disulfide construction have been established. This minireview will focus on the regiospecific, stepwise construction of multiple disulfides used in the chemical synthesis of peptides. We intend for this article to serve a reference for peptide chemists conducting complex peptide syntheses and also hope to stimulate the future development of disulfide methodologies.
Tuning Enzyme Activity for Nonaqueous Solvents: Engineering an Enantioselective “Michaelase” for Catalysis in High Concentrations of Ethanol
Authors: Guo Chao , Biewenga Lieuwe , Lubberink Max , van Merkerk Ronald , Poelarends Gerrit J.
Published: December 2019

Enzymes have evolved to function under aqueous conditions and may not exhibit features essential for biocatalytic application, such as the ability to function in high concentrations of an organic solvent. Consequently, protein engineering is often required to tune an enzyme for catalysis in non‐aqueous solvents. In this study, we have used a collection of nearly all single mutants of 4‐oxalocrotonate tautomerase, which promiscuously catalyzes synthetically useful Michael‐type additions of acetaldehyde to various nitroolefins, to investigate the effect of each mutation on the ability of this enzyme to retain its “Michaelase” activity in elevated concentrations of ethanol. Examination of this mutability landscape allowed the identification of two hotspot positions, Ser30 and Ala33, at which mutations are beneficial for catalysis in high ethanol concentrations. The “hotspot” position Ala33 was then randomized in a highly enantioselective, but ethanol‐sensitive 4‐OT variant (L8F/M45Y/F50A) to generate an improved enzyme variant (L8F/A33I/M45Y/F50A) that showed great ethanol stability and efficiently catalyzes the enantioselective addition of acetaldehyde to nitrostyrene in 40 % ethanol (permitting high substrate loading) to give the desired γ‐nitroaldehyde product in excellent isolated yield (89 %) and enantiopurity (ee=98 %). The presented work demonstrates the power of mutability‐landscape‐guided enzyme engineering for efficient biocatalysis in non‐aqueous solvents.
Nonprecious metal's graphene‐supported electrocatalysts for hydrogen evolution reaction: Fundamentals to applications
Authors: Ali Asad , Shen Pei Kang
Published: December 2019

Sustainable production of hydrogen is a hopeful requirement of a strategic future economy and development. Water splitting driven by electricity is a favorable pathway for renewable hydrogen production. This critical review highlighted recent efforts toward the development of the nanoscale synthesis of nonprecious metal's graphene‐supported electrocatalysts and their electrocatalytic features for remarkable hydrogen evolution reaction (HER). Different essential nonprecious metal's graphene‐supported electrocatalysts, including metal carbides, sulfides, phosphides, selenides, oxides, and nitrides are reviewed. In the exploration, attention is given to the strategies of activity enhancement, the synthetic approach, and the composition/structure electrocatalytic‐performance relationship of these HER electrocatalysts. We are hopeful that this review confers a new momentum to the rational design of remarkable performance nonprecious metal's graphene‐supported electrocatalysts and comprehensive guide for researchers to utilize the subject catalysts in regular water splitting.
Synthesis of β‐Glucosides with 3‐O‐Picoloyl‐Protected Glycosyl Donors in the Presence of Excess Triflic Acid: Defining the Scope
Authors: Mannino Michael P. , Demchenko Alexei V.
Published: December 2019

Excellent β‐stereoselectivity for the glycosylation with glucosyl donors equipped with the 3‐O‐picoloyl (Pico) group, without the use of participating group, was achieved in the presence of NIS/excess TfOH promoter system. A complete investigation of the scope of this reaction was performed, revealing all important attributes of successful glycosylation. While altering the halogen source was tolerated, substitution of the triflate anion resulted in complete loss of stereoselectivity. Protonation of the Pico group was determined to be crucial in this reaction. The stability or extent of the protonated pyridine ring was also found to be another important key factor in obtaining high stereoselectivity. The nucleophilicity of the acceptor was found to be proportional to the stereoselectivity obtained, suggesting an SN2‐like mechanism.
Endohedral Metallofullerenes: New Structures and Unseen Phenomena
Authors: Shen Wangqiang , Hu Shuaifeng , Lu Xing
Published: December 2019

Endohedral metallofullerenes (EMFs), namely fullerenes with metallic species encapsulated inside, represent an ideal platform to investigate metal–metal or metal–carbon interactions at the sub‐nanometer scale by means of single‐crystal X‐ray diffraction (XRD) crystallography. Herein, recent progress in the identification of new structures and unprecedented properties are discussed according to the categories of monometallofullerenes, dimetallofullerenes, carbide clusterfullerenes, and nitride clusterfullerenes. In particular, the dimerization and the cage‐isomer dependent oxidation state of the inner metal atom are summarized in terms of pristine monometallofullerenes. Metal–metal bonds involving lanthanide–lanthanides or actinide–actinides are discussed based on both experimental and theoretical studies. The cluster–cage matching and/or mutual selections, as well as the rarely seen M=C double bonds, are discovered in M2C2@C2n, U2C@C80, M2TiC@C80, and Ti3C3@C80. Subsequently, the geometries of different M3N clusters in various cages are discussed, revealing size‐matching between the internal M3N cluster and the outer cage induced by the planarity of the cluster. Finally, an outlook regarding the future developments of the molecular structures and applications of EMFs is presented.
An evaluation of MPI and OpenMP paradigms in finite‐difference explicit methods for PDEs on shared‐memory multi‐ and manycore systems
Authors: Cabral Frederico L. , Gonzaga de Oliveira Sanderson L. , Osthoff Carla , Costa Gabriel P. , Brandão Diego N. , Kischinhevsky Mauricio
Published: December 2019

This paper focuses on parallel implementations of three two‐dimensional explicit numerical methods on Intel® Xeon® Scalable Processor and the coprocessor Knights Landing. In this study, the performance of a hybrid parallel programming with message passing interface (MPI) and Open Multi‐Processing (OpenMP) and a pure MPI implementation used with two thread binding policies is compared with an improved OpenMP‐based implementation in three explicit finite‐difference methods for solving partial differential equations on shared‐memory multicore and manycore systems. Specifically, the improved OpenMP‐based version is a strategy that synchronizes adjacent threads and eliminates the implicit barriers of a naïve OpenMP‐based implementation. The experiments show that the most suitable approach depends on several characteristics related to the nonuniform memory access (NUMA) effect and load balancing, such as the size of the MPI domain and the number of synchronization points used in the parallel implementation. In algorithms that use four and five synchronization points, hybrid MPI/OpenMP approaches yielded better speedups than the other versions did in runs performed on both systems. The pure MPI‐based strategy, however, achieved better results than the other proposed approaches did in the method that employs only one synchronization point.
Efficient Synthesis of Arylenedioxy‐Bridged Porphyrin Dimers through Catalyst‐Free Nucleophilic Aromatic Substitution
Authors: Yamashita Ken‐ichi , Kuramochi Narumi , Pham Qui Van Hang , Furutani Kazuhiro , Ogawa Takuji , Sugiura Ken‐ichi
Published: December 2019

A series of porphyrin dimers bridged by one or two rigid arylenedioxy linkers was successfully synthesized by catalyst‐free meso‐aryloxylation involving nucleophilic aromatic substitution. The orientational freedom and conformation of the two porphyrin macrocycles in the mono‐bridged dimers depended on the steric hindrance between the macrocycles and substituents on the arylenedioxy linkers. On the other hand, the bis‐bridged dimers exhibited a highly rigid cofacial conformation with a distinct interplanar distance. The fluorescence quantum yields of the bis‐bridged dimers (Φfl=0.094 and 0.096) were quite similar to those of the monomers (Φfl=0.13). Owing to their high rigidities, the nonradiative deactivation of the photoexcited states associated with dimerization, which are observed for reported dimers, are mostly suppressed, thus suggesting that those dimers have highest rigidities among the cofacial porphyrin dimers exploring emission properties. Cyclic voltammetry revealed the electronic communication between the porphyrin macrocycles in the closely stacked bis‐bridged dimer.
The impact of internal control, external assurance, and integrated reports on market value
Authors: Gal Graham , Akisik Orhan
Published: December 2019

It is generally assumed that the credibility of a firm's disclosure is enhanced when there is an independent review. This is the basis for the requirement that an independent audit firm attest to the veracity of financial statements. With the passage of Sarbanes‐Oxley, publicly‐traded North American firms must include a statement about the quality of their internal control system in their financial statements. While the audit of the statements of financial position may be considered to pertain only to that information, the internal control system has a pervasive effect. Therefore, its audit may also impact systems not directly related to financial reporting. Integrated reports combine financial and non‐financial information to provide an overall view of firm's performance. Using data from Compustat North America and GRI, this study shows a positive impact of internal control systems and integrated reports on market value.
Electrocatalytic Hydrogenation of Guaiacol in Diverse Electrolytes Using a Stirred Slurry Reactor
Authors: Wijaya Yanuar Philip , Grossmann‐Neuhaeusler Tobias , Dhewangga Putra Robertus Dhimas , Smith Kevin J. , Kim Chang Soo , Gyenge Előd L.
Published: December 2019

Electrocatalytic hydrogenation (ECH) of guaiacol was performed in a stirred slurry electrochemical reactor (SSER) using 5 wt % Pt/C catalyst in the cathode compartment. Different pairs of acid (H2SO4), neutral (NaCl), and alkaline (NaOH) catholyte–anolyte combinations separated by a Nafion® 117 cation exchange membrane, were investigated by galvanostatic and potentiostatic electrolysis to probe the electrolyte and proton concentration effect on guaiacol conversion, product distribution, and Faradaic efficiency. The acid–acid and neutral–acid pairs were found to be the most effective. In the case of the neutral–acid pair, proton diffusion and migration through the membrane from the anolyte to the catholyte supplies the protons required for ECH. Typically, the two major hydrogenation products were cyclohexanol and 2‐methoxycyclohexanol. However, ECH at constant cathode superficial current density (−182 mA cm−2) and higher temperature (i.e., 60 °C) favored a pathway leading mainly to cyclohexanone. The guaiacol conversion routes were affected by temperature‐ and cathode potential‐dependent surface coverage of adsorbed hydrogen radicals generated through electroreduction of protons.
Photocatalysts for H2 Generation from Starburst Triphenylamine/Carbazole Donor‐Based Metal‐Free Dyes and Porous Anatase TiO2 Cube
Authors: Huang Jian‐Feng , Lei Yang , Xiao Li‐Min , Chen Xin‐Lun , Zhong Yu‐Hui , Qin Su , Liu Jun‐Min
Published: December 2019

A series of novel triphenylamine/carbazole‐based D–D–π–π–A dyes DH1–4 and a mesoporous anatase cubic “microcage” TiO2 material (denoted as MC‐TiO2) were synthesized and combined to obtain dye‐sensitized photocatalysts (denoted as DHn/Pt/MC‐TiO2, n=1–4). These catalysts showed better performances in visible‐light‐driven H2 evolution from water than DHn/Pt/P25‐TiO2 catalysts based on commercial P25‐TiO2 bulk semiconductor under similar conditions. Compared with P25‐TiO2 particles, the porous MC‐TiO2 had a large Brunauer–Emmett–Teller surface area, porosity, and exposed {0 0 1} crystal plane, which greatly contributed to the photocatalytic activity. The optimized DH2/Pt/MC‐TiO2 photocatalyst exhibited an attractive H2 production rate (16.28 mmol g−1 h−1 based on catalyst mass), and the optimized DH4/Pt/MC‐TiO2 photocatalyst showed good stability [turnover number (TON) of 16 699 in 105 h based on dye number], which represents one of the best performances among all reported visible‐light‐driven heterogeneous catalytic systems. Compared with the other dyes in this series, the high H2 production rate of DH2 on Pt/MC‐TiO2 can be attributed to its size‐matching effect and thus high dye loading amount, whereas the high TON and durability of DH4/Pt/MC‐TiO2 are probably related to the rapid regeneration kinetics of DH4.
Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen
Authors: Jing Yaxuan , Dong Lin , Guo Yong , Liu Xiaohui , Wang Yanqin
Published: December 2019

Lignin is the most abundant biopolymer with aromatic building blocks and its valorization to sustainable chemicals and fuels has extremely great potential to reduce the excessive dependence on fossil resources, although such conversions remain challenging. The purpose of this Review is to present an insight into the catalytic conversion of lignin involving hydrogen, including reductive depolymerization and the hydrodeoxygenation of lignin‐derived monomers to arenes, cycloalkanes and phenols, with a main focus on the catalyst systems and reaction mechanisms. The roles of hydrogenation sites (Ru, Pt, Pd, Rh) and acid sites (Nb, Ti, Mo), as well as their interaction in selective hydrodeoxygenation reactions are emphasized. Furthermore, some inspirational strategies for the production of other value‐added chemicals are mentioned. Finally, some personal perspectives are provided to highlight the opportunities within this attractive field.
Prenatal immobilization stress and postnatal maternal separation cause differential neuroendocrine responses to fasting stress in adult male rats
Authors: Roque Angélica , Ruiz‐González Roberto , Pineda-López Edel , Torner Luz , Lajud Naima
Published: December 2019

Prenatal immobilization stress (PNS) and postnatal maternal separation (MS180) are two widely used rodent models of early‐life stress (ELS) that affect the hypothalamus–pituitary–adrenal (HPA) axis, cause behavioral alterations, and affect glucose tolerance in adults. We compared anxiety‐like behavior, coping strategies, and HPA axis activity in PNS and MS180 adult (4‐month‐old) male rats and assessed their glucose tolerance and HPA axis response after mild fasting stress. Both PNS and MS180 induced a passive coping strategy in the forced swimming test, without affecting anxiety‐like behavior in the elevated plus‐maze. Moreover, both PNS and MS180 increased the hypothalamic corticotropin‐releasing hormone expression; however, only MS180 increased the circulating corticosterone levels. Both early life stressors increased fasting glucose levels and this effect was significantly higher in PNS rats. MS180 rats showed impaired glucose tolerance 120 min after intravenous glucose administration, whereas PNS rats displayed an efficient homeostatic response. Moreover, MS180 rats showed higher circulating corticosteroid levels in response to fasting stress (overnight fasting, 12 hr), which were restored after glucose administration. In conclusion, early exposure to postnatal MS180, unlike PNS, increases the HPA axis response to moderate fasting stress, indicating a differential perception of fasting as a stressor in these two ELS models.
A Highly α‐Stereoselective Sialylation Method Using 4‐O‐4‐Nitropicoloyl Thiosialoside Donor
Authors: Liu Dong‐Mei , Wang Hong‐Ling , Lei Jin‐Cai , Zhou Xian‐Yang , Yang Jin‐Song
Published: December 2019

An efficient α‐sialylation methodology for various primary, secondary, and tertiary alcohol acceptors has been developed. The sialic acid ethyl thioglycoside 1b, bearing a 4‐nitropicoloyl moiety as the stereodirecting group at the C4 position, was utilized as the glycosyl donor, and the sialylation reaction was activated with N‐iodosuccinimide and catalytic triflic acid in a 1:1 mixture of dichloromethane/acetonitrile as solvent. The method was successfully applied to the stereocontrolled synthesis of protected trisaccharide 11 found in the repeating unit of serotype Ia Group B Streptococcus capsular polysaccharide.