bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuous Growth of Germanene and Stanene Lateral Heterostructures
Authors: Ogikubo Tsuyoshi , Shimazu Hiroki , Fujii Yuya , Ito Koichi , Ohta Akio , Araidai Masaaki , Kurosawa Masashi , Le Lay Guy , Yuhara Junji
Published: March 2020

Group 14 elemental post‐graphene materials receive much attention because of their outstanding properties, typically, as robust 2D topological insulators. Their heterostructures are a main target in view of disruptive applications. Here, the realization of striking in‐plane lateral heterostructures between germanene and stanene are shown, which are sustainable 2D Ge‐ and Snbased graphene analogs, but with a strong intrinsic spin–orbit coupling. A unique combination of atomic segregation epitaxy (ASE) and molecular beam epitaxy (MBE) for the in situ continuous fabrication of nearly atomically precise lateral multijunction heterostructures, respectively, consisting of atom‐thin germanene and stanene on a Ag(111) thin film is used. Scanning tunneling microscopy (STM) observations at atomic scale and low‐energy electron diffraction testify that germanene and stanene sheets without intermixing are prepared simultaneously on the same terraces at wide scale: tin and germanium atoms neither exchange their sites nor adsorb on the germanene and stanene sheets. The atomic structure of the boundary between germanene and stanene is derived from STM images, while scanning tunneling spectroscopy reveals key electronic features at the heterojunction. This innovative synergetic approach of ASE and MBE growths offers great flexibility for the realization of unprecedented lateral 2D heterostructures.
Superior Self‐Charged and ‐Powered Chemical Sensing with High Performance for NO2 Detection at Room Temperature
Authors: Chen Hongjun , Zhang Meng , Xing Bobo , Fu Xiao , Bo Renheng , Mulmudi Hemant Kumar , Huang Shujuan , Ho‐Baillie Anita W. Y. , Catchpole Kylie R. , Tricoli Antonio
Published: March 2020

Halide based lead perovskites are recently being explored as efficient light harvesters for optoelectronics devices. Here, some new insights on the self‐charging and energy‐storage of triple cation FA0.80MA0.15Cs0.05PbI2.55Br0.45 (FMCPIB) perovskites based devices with the application for self‐powered chemical sensing are presented. It is demonstrated that under light irradiation a self‐powered FMCPIB based device can detect particle per million (ppm) concentrations of nitrogen dioxide (NO2) with a swift response and recovery time of ≈17 and ≈126 s at room temperature, respectively. Most notably, the energy‐storage feature enables FMCPIB based devices like a photo‐capacitor, and then remain operational for another 1.7 h in darkness for the detection of NO2 without external power supply. Besides, the FMCPIB based devices can also be operated with a 1 V bias achieving a detection limit 0.2 ppm of NO2 at room temperature. Through analysis, it reveals that the high performance for NO2 can be ascribed to the special NO2‐amine interaction with the cations of FMCPIB and the storage capacitance might be due to the accumulation of charges at the TiO2/FMCPIB/carbon interfaces under light irradiation. These appealing features of FMCPIB perovskites based chemical sensors might find potential applications in monitoring of toxic gas emission and public space safety.
Flatband Line States in Photonic Super‐Honeycomb Lattices
Authors: Yan Wenchao , Zhong Hua , Song Daohong , Zhang Yiqi , Xia Shiqi , Tang Liqin , Leykam Daniel , Chen Zhigang
Published: March 2020

For the first time, a photonic super‐honeycomb lattice (sHCL) is established experimentally by use of a continuous‐wave laser writing technique, and thereby two distinct flatband line states that manifest as noncontractible loop states in an infinite flatband lattice are demonstrated. These localized states (“straight” and “zigzag” lines) observed in the sHCL with tailored boundaries cannot be obtained by the superposition of conventional compact localized states because they arise from real‐space topological property of certain flatband systems. In fact, the zigzag‐line states, unique to the sHCL, are in contradistinction with those previously observed in the Kagome and Lieb lattices. Their momentum‐space spectrum emerges in the high‐order Brillouin zone where the flatband touches the dispersive bands, revealing the characteristic of topologically protected band‐touching. The experimental results are corroborated by numerical simulations. This work may provide insight into Dirac‐like 2D materials beyond graphene.
Nanostructured Germanium with >99% Absorption at 300–1600 nm Wavelengths
Authors: Pasanen Toni P. , Isometsä Joonas , Garin Moises , Chen Kexun , Vähänissi Ville , Savin Hele
Published: March 2020

Near‐infrared (NIR) sensors find numerous applications within various industry fields, including optical communications and medical diagnostics. However, the state‐of‐the‐art NIR sensors made of germanium (Ge) suffer from rather poor response, largely due to high reflection from the illuminated device surface. This work demonstrates a method to increase the sensitivity of Ge sensors by implementing nanostructures to the wafer surfaces. The absorbance of nanostructured Ge wafers is measured to be >99% in the whole UV–vis–NIR spectrum up to 1600 nm wavelength, which is a significant improvement to bare Ge wafers that reach absorption of only 63% in maximum. The process is shown to be capable of producing uniform nanostructures covering full 100 mm diameter substrates as well as wafers with etch mask openings of different sizes and shapes, which demonstrates its applicability to complementary metal oxide semiconductor (CMOS) sensor manufacturing. The results imply that nanostructured Ge has potential to revolutionize the sensitivity of Ge‐based sensors.
Methylammonium Lead Tribromide Single Crystal Detectors towards Robust Gamma‐Ray Photon Sensing
Authors: Tisdale Jeremy T. , Yoho Michael , Tsai Hsinhan , Shrestha Shreetu , Fernando Kasun , Baldwin Jon K. , Tretiak Sergei , Vo Duc , Nie Wanyi
Published: March 2020

In recent years, hybrid perovskite single crystalline solid‐state detectors have shown promise in γ‐ray spectroscopy. Here, the γ‐ray photon induced electrical pulses are investigated, which are produced by perovskite solid‐state detectors made with the commonly used methylammonium lead tribromide crystals with chlorine incorporation. Under low electric field detector operation, slow pulses generated by γ‐rays with average rise times of 65 µs are observed, which decreases to 20 µs when a higher electrical field of 500 V cm−1 is applied. However, the baseline becomes noisy quickly, which prevents collection of clean pulses for spectra construction. Further, by systematically measuring the temperature dependence and current–voltage characteristics, such instability is attributed to the local ion migration under electrical field creating a fluctuating dark noise, which presents a major challenge in perovskite γ‐ray detector technologies. It is demonstrated that cycling the bias between positive and negative polarity can stabilize the detector, allowing for longer periods of pulse accumulation for generating energy resolved spectra with resolutions of ≈35% at 59.6 keV and ≈25% at 662 keV at room temperature. The study indicates that the main limiting factors of perovskite‐based γ‐ray detectors are slow rise times and bias instability. These challenges must be properly addressed to achieve reproducible, high‐resolution γ‐ray detection.
Increasing Complexity to Simplify Clinical Care: High Resolution Mass Spectrometry as an Enabler of AI Guided Clinical and Therapeutic Monitoring
Authors: Yee Wei Loong Sherman , Drum Chester Lee
Published: March 2020

Clinical care increasingly relies on individualized, highly multidimensional data for patient phenotyping. This review focusses on two technologies which are contributing to this trend and, in their mutual overlap, may provide a novel and powerful contribution to future clinical care. Artificial intelligence (AI), in particular the technique of deep learning, is steadily making inroads to clinical care and has demonstrated the ability to extract clinically relevant features from complex datasets. Likewise, mass spectrometry (MS), in particular high‐resolution MS, is gaining the ability to provide highly multidimensional datasets from patient samples with the quality necessary for clinical decision making. The convergence of these trends has resulted in the nascent application of deep learning analytics to high resolution mass spectra. Due to the large volumes of content provided by high resolution mass spectra and the ability of multilayer neural networks to extract subtle features from complex datasets, future integration of their mutual application is identified as a research area of high priority for clinical care. Factors are identified that have contributed to historical progress for each technology and recommendations are provided to accelerate the mutual application of deep learning and mass spectrometry techniques to patient care.
Quantum Dynamics Simulations on the Adsorption Mechanism of Reducing and Oxidizing Gases on the CH3NH3PbI3 Surface
Authors: Tong Lei , Zhang Bing , Wang Xiaogang G. , Liao Yinjie J. , Yang Jieqin Q.
Published: March 2020

Existing experiments have revealed that methylammonium lead iodide (MAPbI3 or CH3NH3PbI3) materials show favorable gas‐sensing properties to reducing gas NH3 and oxidizing gases O2 and O3. The first step to effective gas‐sensing by using semiconductor materials for gas‐sensing applications is to recognize a target gas through gas–solid interaction. To explore the sensing mechanisms of perovskite materials to different oxidizing and reducing gases, the changes of skeleton structures of MAPbI3 in reducing gas NH3 and oxidizing gases O2 and O3, adsorption energy, and charge transfer between gases and semiconductors are investigated through large‐scale quantum dynamics simulations. By using three adsorption models, the differences and similarities of adsorption mechanisms of MAPbI3 for gases NH3, O2, and O3 are illustrated. These adsorption mechanisms are expected to provide new ideas for developing innovative sensing elements made of perovskite materials with stronger stability, high sensitivity, and high selectivity.
Water Permeation through Conical Nanopores: Complex Interplay between Surface Roughness and Chemistry
Authors: Nalaparaju Anjaiah , Wang John , Jiang Jianwen
Published: March 2020

Inspired by biological water channels (e.g., aquaporin with an hourglass shape), there is a growing interest in the use of conical nanopores for water purification; however, the surface roughness of conical nanopores has not been considered in the literature. In this work, a molecular dynamics simulation study is conducted to investigate water permeation through conical nanopores by considering both surface roughness and chemistry. In hydrophilic alumina nanopores, water permeability is found to increase with increasing surface roughness; however, a reverse trend is observed in hydrophobic carbon nanopores. Comprehensive microscopic analysis reveals that surface roughness in the carbon nanopores induces multiple high‐energy barriers and frequent forming/breaking of hydrogen bonding network, which impedes water permeation. In the alumina nanopores, water becomes more bulk‐like with increasing surface roughness, thus enhancing water permeation. The molecular insights from this simulation study provide quantitative understanding of water permeation in hydrophilic and hydrophobic conical nanopores and unravel the complex interplay between surface roughness and chemistry, facilitating the design of new materials for water purification.
Novel All‐Nitrogen Molecular Crystals of Aromatic N10
Authors: Liu Shijie , Zhao Lei , Yao Mingguang , Miao Maosheng , Liu Bingbing
Published: March 2020

Nitrogen has unique bonding ability to form single, double, and triple bonds, similar to that of carbon. However, a molecular crystal formed by an aromatic polynitrogen similar to a carbon system has not been found yet. Herein, a new form of stable all‐nitrogen molecular crystals consisting of only bispentazole N10 molecules with exceedingly high energy density is predicted. The crystal structures and the conformation of N10 molecules are strongly correlated, both depending on the applied external pressure. These molecular crystals can be recovered upon the release of the pressure. The first‐principles molecular dynamics simulations reveal that these all‐nitrogen materials decompose at temperatures much higher than room temperature. The decompositions always start from breaking off N2 molecules from the nitrogen ring and can release a large amount of energy. These new polynitrogens are aromatic and are more stable than all the other polynitrogen crystals reported previously, providing a new green strategy to get all‐nitrogen, nonpolluting high energy density materials without introducing any metal or other guest stabilizer.
Medical Gas Plasma Jet Technology Targets Murine Melanoma in an Immunogenic Fashion
Authors: Bekeschus Sander , Clemen Ramona , Nießner Felix , Sagwal Sanjeev Kumar , Freund Eric , Schmidt Anke
Published: March 2020

Medical technologies from physics are imperative in the diagnosis and therapy of many types of diseases. In 2013, a novel cold physical plasma treatment concept was accredited for clinical therapy. This gas plasma jet technology generates large amounts of different reactive oxygen and nitrogen species (ROS). Using a melanoma model, gas plasma technology is tested as a novel anticancer agent. Plasma technology derived ROS diminish tumor growth in vitro and in vivo. Varying the feed gas mixture modifies the composition of ROS. Conditions rich in atomic oxygen correlate with killing activity and elevate intratumoral immune‐infiltrates of CD8+ cytotoxic T‐cells and dendritic cells. T‐cells from secondary lymphoid organs of these mice stimulated with B16 melanoma cells ex vivo show higher activation levels as well. This correlates with immunogenic cancer cell death and higher calreticulin and heat‐shock protein 90 expressions induced by gas plasma treatment in melanoma cells. To test the immunogenicity of gas plasma treated melanoma cells, 50% of mice vaccinated with these cells are protected from tumor growth compared to 1/6 and 5/6 mice negative control (mitomycin C) and positive control (mitoxantrone), respectively. Gas plasma jet technology is concluded to provide immunoprotection against malignant melanoma both in vitro and in vivo.
External‐Field‐Free Spin Hall Switching of Perpendicular Magnetic Nanopillar with a Dipole‐Coupled Composite Structure
Authors: Zhao Zhengyang , Smith Angeline K. , Jamali Mahdi , Wang Jian‐Ping
Published: March 2020

Spin Hall effect (SHE)‐induced reversal of perpendicular magnetization has attracted significant interest, due to its potential for low‐power memory and logic devices. However, the switching requires an assisted in‐plane magnetic field, which hampers its practical applications. Here, a new approach for external‐field‐free spin Hall switching of a perpendicular nanomagnet is introduced. This approach utilizes a local dipolar field arising from an in‐plane biasing layer to assist the switching. Robust switching of a 285 × 95 nm2 perpendicular CoFeB nanomagnet is demonstrated in the absence of any external magnetic field. Micromagnetic simulation is performed to illustrate the magnetic dynamics of the switching process. Large in‐plane compensation field of 135 Oe is obtained in the composite nanodevices, reflecting a strong symmetry‐breaking behavior. Compared with other proposed methods for external‐field‐free spin Hall switching, the dipole‐coupled composite structure is compatible with a wide range of spin Hall systems and perpendicular magnetic tunnel junctions, paving a way towards practical spin–orbit torque‐based memory and logic applications.
Global Health Training in U.S. Emergency Medicine Residency Programs
Authors: Rybarczyk Megan M. , Muck Andrew , Kolkowitz Ilan , Tupesis Janis P. , Jacquet Gabrielle A.
Published: March 2020

Objectives

Formal education in global health (GH) and short‐term experiences in GH (STEGH) are offered by many emergency medicine (EM) residency programs in the United States. In an increasingly connected world, training in GH and STEGH can provide essential knowledge and practical skills to trainees, particularly at the graduate medical education level. The current core programmatic components and the essential competencies and curricula that support ethical and effective STEGH, however, still vary widely. The authors conducted a survey of the 228 EM residency programs in the United States to describe the current state of GH training and STEGH.

Methods

An online survey was developed in REDCap by a team of GH faculty. In July 2018, programs were invited to participate via individual invitation of program directors from a directory. The programs received two reminders to participate until January 2019.

Results

Of the 84 programs that responded, 75% offer STEGH and 39% have longitudinal GH curricula. Within these programs, only 55% have dedicated GH faculty and only 70% have dedicated sites. Both faculty and residents encounter funding and insurance barriers; most notably, only 20% of programs that offer STEGH provide evacuation insurance for their residents. Most residents (95%) engage in clinical work along with teaching and other activities, but 24% of programs do not allow these activities to fulfill any residency requirements. Finally, only 80 and 85% of programs offer preparatory and debriefing activities for residents, respectively.

Conclusions

While the results of this survey show progress relative to prior surveys, there are still barriers to implementing GH curricula and supporting safe, ethical, and effective STEGH, particularly in the form of continued financial and logistic support for faculty and for residents, in U.S. EM training programs.
Hydroseeding with mesotrione in tankmix for establishment of perennial ryegrass
Authors: Pease B.W. , Stier J.C.
Published: March 2020

Mesotrione (2‐[4‐(methylsulfonyl)‐2‐nitrobenzoyl]‐1,3‐cyclohexanedione) is a proven effective weed control product in agricultural and turf settings but its use within a hydroseeding mixture has not been investigated. Two experiments were conducted to evaluate the effects of (1) mesotrione rate and (2) duration of herbicide exposure on turf establishment and weed populations through hydroseeding establishment methodology. The experimental design of both studies was a randomized complete block, incorporating a split‐plot in the second study, with four replications and repeated in two years. Perennial ryegrass (Lolium perenne L., variety not stated) was hydroseeded on a silt loam soil (pH 7.0) in summer at 39 g m−2 in a slurry delivering 6.1 L m−2. Treatments in the first study were mesotrione rates of 0.000, 0.088, 0.175, and 0.263 kg a.i. ha−1. Treatments in the second study were duration of mixture in tank before applying of 0, 2, and 4 h, with and without mesotrione at 0.175 kg a.i. ha−1. Turfgrass percent cover, turfgrass injury, and weed populations were assessed for both studies. The addition of mesotrione at any rate to the hydroseeding slurry did not reduce desired turf populations; in many cases, the amount of desired turf cover increased. Weed populations were significantly reduced by all mesotrione rates; the effect was most evident at the two highest rates. No treatments caused turf injury. Length of time in the hydroseeding slurry did not reduce herbicide efficacy or desired turf populations, or cause turf injury.
Gigantic chloroplasts, including bizonoplasts, are common in shade‐adapted species of the ancient vascular plant family Selaginellaceae
Authors: Liu Jian‐Wei , Li Shau‐Fu , Wu Chin‐Ting , Valdespino Iván A. , Ho Jia‐Fang , Wu Yeh‐Hua , Chang Ho‐Ming , Guu Te‐Yu , Kao Mei‐Fang , Chesson Clive , Das Sauren , Oppenheimer Hank , Bakutis Ane , Saenger Peter , Salazar Allen Noris , Yong Jean W. H. , Adjie Bayu , Kiew Ruth , Nadkarni Nalini , Huang Chun‐Lin , Chesson Peter , Sheue Chiou‐Rong
Published: March 2020

Premise

Unique among vascular plants, some species of Selaginella have single giant chloroplasts in their epidermal or upper mesophyll cells (monoplastidy, M), varying in structure between species. Structural variants include several forms of bizonoplast with unique dimorphic ultrastructure. Better understanding of these structural variants, their prevalence, environmental correlates and phylogenetic association, has the potential to shed new light on chloroplast biology unavailable from any other plant group.

Methods

The chloroplast ultrastructure of 76 Selaginella species was studied with various microscopic techniques. Environmental data for selected species and subgeneric relationships were compared against chloroplast traits.

Results

We delineated five chloroplast categories: ME (monoplastidy in a dorsal epidermal cell), MM (monoplastidy in a mesophyll cell), OL (oligoplastidy), Mu (multiplastidy, present in the most basal species), and RC (reduced or vestigial chloroplasts). Of 44 ME species, 11 have bizonoplasts, cup‐shaped (concave upper zone) or bilobed (basal hinge, a new discovery), with upper zones of parallel thylakoid membranes varying subtly between species. Monoplastidy, found in 49 species, is strongly shade associated. Bizonoplasts are only known in deep‐shade species (<2.1% full sunlight) of subgenus Stachygynandrum but in both the Old and New Worlds.

Conclusions

Multiplastidic chloroplasts are most likely basal, implying that monoplastidy and bizonoplasts are derived traits, with monoplastidy evolving at least twice, potentially as an adaptation to low light. Although there is insufficient information to understand the adaptive significance of the numerous structural variants, they are unmatched in the vascular plants, suggesting unusual evolutionary flexibility in this ancient plant genus.
An Endergonic Synthesis of Single Sondheimer–Wong Diyne by Local Probe Chemistry
Authors: Kawai Shigeki , Sang Hongqian , Kantorovich Lev , Takahashi Keisuke , Nozaki Kyoko , Ito Shingo
Published: March 2020

Recent advances in scanning probe microscopy on surface enable not only direct observation of molecular structures but also local probe reactions, in which unstable short‐lived products have been synthesized and analyzed. Now, an endergonic reaction to synthesize a single Sondheimer–Wong diyne from 6,13‐dibromopentaleno[1,2‐b:4,5‐b′]dinaphthalene by local probe chemistry on a ultra‐thin film of NaCl formed on a Cu(111) surface at 4.3 K is presented. The structures of the precursor, two intermediates, and the final product were directly identified by the differential conductance imaging with a CO functionalized tip. DFT calculations revealed that the multiple‐step reaction, being endergonic overall, is facilitated by temporal charging and discharging of the molecule placed in the nanometric junction between the Cu tip and the Cu substrate underneath the ultra‐thin NaCl film. This local probe reaction expands possibilities to synthesize nanocarbon materials in a bottom‐up manner.
Electrophotocatalytic Decarboxylative C−H Functionalization of Heteroarenes
Authors: Lai Xiao‐Li , Shu Xiao‐Min , Song Jinshuai , Xu Hai‐Chao
Published: March 2020

Decarboxylative C−H functionalization reactions are highly attractive methods for forging carbon–carbon bonds considering their inherent step‐ and atom‐economical features and the pervasiveness of carboxylic acids and C−H bonds. An ideal approach to achieve these dehydrogenative transformations is through hydrogen evolution without using any chemical oxidants. However, effective couplings by decarboxylative carbon–carbon bond formation with proton reduction remain an unsolved challenge. Herein, we report an electrophotocatalytic approach that merges organic electrochemistry with photocatalysis to achieve the efficient direct decarboxylative C−H alkylation and carbamoylation of heteroaromatic compounds through hydrogen evolution. This electrophotocatalytic method, which combines the high efficiency and selectivity of photocatalysis in promoting decarboxylation with the superiority of electrochemistry in effecting proton reduction, enables the efficient coupling of a wide range of heteroaromatic bases with a variety of carboxylic acids and oxamic acids. Advantageously, this method is scalable to decagram amounts, and applicable to the late‐stage functionalization of drug molecules.
“Anti‐Electrostatic” Halogen Bonding
Authors: Holthoff Jana M. , Engelage Elric , Weiss Robert , Huber Stefan M.
Published: March 2020

Halogen bonding is often described as being driven predominantly by electrostatics, and thus adducts between anionic halogen bond (XB) donors (halogen‐based Lewis acids) and anions seem counterintuitive. Such “anti‐electrostatic” XBs have been predicted theoretically but for organic XB donors, there are currently no experimental examples except for a few cases of self‐association. Reported herein is the synthesis of two negatively charged organoiodine derivatives that form anti‐electrostatic XBs with anions. Even though the electrostatic potential is universally negative across the surface of both compounds, DFT calculations indicate kinetic stabilization of their halide complexes in the gas phase and particularly in solution. Experimentally, self‐association of the anionic XB donors was observed in solid‐state structures, resulting in dimers, trimers, and infinite chains. In addition, co‐crystals with halides were obtained, representing the first cases of halogen bonding between an organic anionic XB donor and a different anion. The bond lengths of all observed interactions are 14–21 % shorter than the sum of the van der Waals radii.
Organoboron‐Functionalization Enables the Hierarchical Assembly of Giant Polyoxometalate Nanocapsules
Authors: Li Shujun , Zhou Yanfang , Ma Nana , Zhang Jie , Zheng Zhiping , Streb Carsten , Chen Xuenian
Published: March 2020

The aggregation of molecular metal oxides into larger superstructures can bridge the gap between molecular compounds and solid‐state materials. Here, we report that functionalization of polyoxotungstates with organo‐boron substituents leads to giant polyoxometalate‐based nanocapsules with dimensions of up to 4 nm. A “lock and key” mechanism enables the site‐specific anchoring of aromatic organo‐boronic acids to metal‐functionalized Dawson anions [M3P2W15O62]9− (M=TaV or NbV), resulting in unique nanocapsules containing up to twelve POM units. Experimental and theoretical studies provide initial insights into the role of the organo‐boron moieties and the metal‐functionalized POMs for the assembly of the giant aggregates. The study therefore lays the foundations for the design of organo‐POM‐based functional nanostructures.
Functional analysis of novel sulfotransferases in the silkworm Bombyx mori
Authors: Bairam Ahsan F. , Kermasha Zainab W. , Liu Ming‐Cheh , Kurogi Katsuhisa , Yamamoto Kohji
Published: March 2020

Sulfoconjugation plays a vital role in the detoxification of xenobiotics and in the metabolism of endogenous compounds. In this study, we aimed to identify new members of the sulfotransferase (SULT) superfamily in the silkworm Bombyx mori. Based on amino acid sequence and phylogenetic analyses, two new enzymes, swSULT ST1 and swSULT ST2, were identified that appear to belong to a distinct group of SULTs including several other insect SULTs. We expressed, purified, and characterized recombinant SULTs. While swSULT ST1 sulfated xanthurenic acid and pentachlorophenol, swSULT ST2 exclusively utilized xanthurenic acid as a substrate. Based on these results, and those concerning the tissue distribution and substrate specificity toward pentachlorophenol analyses, we hypothesize that swSULT ST1 plays a role in the detoxification of xenobiotics, including insecticides, in the silkworm midgut and in the induction of gametogenesis in silkworm ovary and testis. Collectively, the data obtained herein contribute to a better understanding of SULT enzymatic functions in insects.
Regulation of 2D Graphene Materials for Electrocatalysis
Authors: Zhang Xinqun , Gao Jian , Xiao Yukun , Wang Jiaqi , Sun Guoqiang , Zhao Yang , Qu Liangti
Published: March 2020

Benefiting from unique excellent physical and chemical characteristics, graphene has attracted widespread attention in the application of electrocatalysis. As a promising candidate, graphene is usually regulated with surface defects, heteroatoms, metal atoms and other active materials through covalent or non‐covalent bonds to substitute for noble metal catalysts, which has not been targeted in a report yet. In this review, we summarize the recent advances of approaches for engineering graphene‐based electrocatalysts and emphasize the corresponding electrocatalytic active sites in various electrocatalysis circumstances, such as electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), etc. The opportunities and challenges in the future development of graphene‐based catalysts are also discussed.
Ghost Introgression: Spooky Gene Flow in the Distant Past
Authors: Ottenburghs Jente
Published: March 2020

Evolution is a continuous trial and error process in which most lineages go extinct without leaving fossil remains. Many of these lineages would be closely related and occasionally hybridized with lineages that gave rise to extant species. Hence, it is likely that one can find genetic signatures of these ancient introgression events in present‐day genomes, so‐called ghost introgression. The increasing availability of high‐quality genome assemblies for non‐model organisms and the development of more sophisticated methods for detecting introgression will undoubtedly reveal more cases of ghost introgression, indicating that the Tree of Life is even more reticulated than assumed. The presence of ghost introgression has important consequences for the study of numerous evolutionary processes, including adaptation, speciation, and macroevolutionary patterns. In addition, detailed studies of introgressed regions could provide insights into the morphology of the extinct lineage, providing an unexpected link between genomics and the fossil record. Hence, new methods that take into account ghost introgression will need to be developed.
Research and application of situated teaching design for NC machining course based on virtual simulation technology
Authors: Li Meng , Li Yongxiang , Guo Haixia
Published: March 2020

As virtual simulation technology can display three‐dimensional materials as well as their dynamic cutting process and the learners’ motivation is enhanced in the situated learning environment, a virtual‐situated learning system for numerical control (NC) machining course is proposed to explore the learning effectiveness of learners when combining virtual simulation technology and the situation learning theory. This study aims to use the concept of embedding NC machining simulation system and the situated learning into a real situation to improve the learners’ situated thinking ability and innovative literacy. The features of the system include (a) the learning activities and contents that are planned and designed using the key factors of situated learning based on the specific teaching contents and objectives, (b) combining virtual objects with a real environment using virtual simulation technology to provide a project‐based learning situation for learners, and (c) probing into the specific methods of implementing situated teaching design in NC machining course. To assess the acceptance of the proposed system, an independent sample t‐test was then applied to evaluate the learning achievement of learners. The results show that the research scale is highly reliable and that all assumptions made are valid. In addition, the effect of the situated teaching was investigated through questionnaire survey. The experimental results suggest that the virtual‐situated teaching design has significant positive impact on improving the students' learning efficiency and performance skills and indicates that the participants were attracted to and willing to use the system, which directly enhances their incentive to actively learn and promote learning achievement.
Trichodermaloids A–C, Cadinane Sesquiterpenes from a Marine Sponge Symbiotic Trichoderma sp. SM16 Fungus
Authors: Cui Jie , Shang Ru‐Yi , Sun Mei , Li Yi‐Xuan , Liu Hong‐Yan , Lin Hou‐Wen , Jiao Wei‐Hua
Published: March 2020

Three new cadinane sesquiterpenes, trichodermaloids A (1), B (2), and C (5) were isolated from a symbiotic fungus Trichoderma sp. SM16 derived from the marine sponge Dysidea sp., together with three known ones, aspergilloid G (3), rhinomilisin E (4), and rhinomilisin G (6). The complete structures of three new compounds were determined by HR‐MS and NMR spectroscopic analyses coupled with ECD calculations. The absolute configurations of two known compounds (4 and 6) were determined for the first time. The six isolates were inactive as antibacterial agents. However, trichodermaloids A and B have shown cytotoxicity on human NCIH‐460 lung, NCIC‐H929 myeloma, and SW620 colorectal cancer cell lines with IC50 values at the range of 6.8–12.7 μm.
Enzyme Mimic Nanomaterials and Their Biomedical Applications
Authors: Shang Yingxu , Liu Fengsong , Wang Yuanning , Li Na , Ding Baoquan
Published: March 2020

Nanomaterials with enzyme‐mimicking behavior (nanozymes) have attracted a lot of research interest recently. In comparison to natural enzymes, nanozymes hold many advantages, such as good stability, ease of production and surface functionalization. As the catalytic mechanism of nanozymes is gradually revealed, the application fields of nanozymes are also broadly explored. Beyond traditional colorimetric detection assays, nanozymes have been found to hold great potential in a variety of biomedical fields, such as tumor theranostics, antibacterial, antioxidation and bioorthogonal reactions. In this review, we summarize nanozymes consisting of different nanomaterials. In addition, we focus on the catalytic performance of nanozymes in biomedical applications. The prospects and challenges in the practical use of nanozymes are discussed at the end of this Minireview.
Liquid‐Phase Exfoliation and Functionalization of MoS2 Nanosheets for Effective Antibacterial Application
Authors: Ma Dongqing , Xie Changjian , Wang Tao , Mei Linqiang , Zhang Xiao , Guo Zhao , Yin Wenyan
Published: March 2020

A lysozyme (Lys)‐assisted liquid‐phase exfoliation technique was designed to synthesize MoS2 nanosheets (MoS2‐Lys NSs). As a novel nanozyme antibacterial agent with high peroxidase‐like catalyst activity, MoS2‐Lys NSs showed good antibacterial efficacy against both Gram‐negative ampicillin‐resistant Escherichia coli (Ampr E. coli) and Gram‐positive Bacillus subtilis. A possible antibacterial mechanism is also proposed. This work provides an effective antibacterial strategy based on the MoS2‐Lys NSs antibacterial agent.
Manganese Oxide Derived from a Spent Zn–C Battery as a Catalyst for the Oxygen Evolution Reaction
Authors: Farzana Rifat , Sayeed Md Abu , Joseph Jickson , Ostrikov Kostya (Ken) , O'Mullane Anthony P. , Sahajwalla Veena
Published: March 2020

The generation of efficient, cheap and easily available water splitting catalysts, in particular for the oxygen evolution reaction (OER), is vital to the development of sustainable energy sources. Primary batteries, especially alkaline and Zn−C batteries, mostly end‐up in landfill due to their short lifespan which aggravates health and poses environmental threats. To address these issues, this work establishes a sustainable route for the generation of Manganese oxide (Mn3O4) from spent Zn−C batteries as a catalyst for the OER under alkaline conditions. A thermal transformation study is conducted here at 900 °C and 800 °C under controlled atmosphere to generate Mn3O4 nanoparticles from waste Zn−C batteries which are investigated as a potential OER catalyst. Mn3O4 particle synthesis was confirmed by XRD, Raman, FTIR, TEM and EDS analysis. The electrochemical performance demonstrated a low overpotential of 360 mV to reach 10 mA cm−2 with a Tafel slope of 64 mV dec−1 indicating good activity under alkaline conditions. Thus, the generation of Mn3O4 from a spent Zn−C battery that can be employed as a catalyst for the OER is a promising path not only for the effective extraction of resources from battery waste, but also for the exploitation of using extracted materials in advanced technology applications.
Ambident Reactivity of Imidazolium Cations as Evidence of the Dynamic Nature of N‐Heterocyclic Carbene‐Mediated Organocatalysis
Authors: Galkin Konstantin I. , Karlinskii Bogdan Ya. , Kostyukovich Alexander Yu. , Gordeev Evgeniy G. , Ananikov Valentine P.
Published: March 2020

This work reveals ambident nucleophilic reactivity of imidazolium cations towards carbonyl compounds at the C2 or C4 carbene centers depending on the steric properties of the substrates and reaction conditions. Such an adaptive behavior indicates the dynamic nature of organocatalysis proceeding via a covalent interaction of imidazolium carbenes with carbonyl substrates and can be explained by generation of the H‐bonded ditopic carbanionic carbenes.
Cooperative and Independent Effect of Modular Functionalization on Mesomorphic Performances and Microphase Separation of Well‐Designed Liquid Crystalline Diblock Copolymers
Authors: Lei Lan , Han Li , Ma Hongwei , Zhang Ruixue , Huang Shuai , Shen Heyu , Yang Lincan , Li Chao , Zhang Songbo , Bai Hongyuan , Ma Qingchi , Li Yang
Published: March 2020

Liquid crystalline block copolymers (LCBCPs) are promising for developing functional materials owing to an assembly of better functionalities. Taking advantage of differences in reactivity between alkynyl and vinyl over temperature during hydrosilylation, a series of LCBCPs with modular functionalization of the block copolymers (BCPs) are reported by independently and site‐selectively attaching azobenzene moieties containing alkynyl (LC1) and Si‐H (LC2) terminals into well‐designed poly(styrene)‐block‐polybutadienes (PS‐b‐PBs) and poly(4‐vinylphenyldimethylsilane)‐block‐polybutadienes (PVPDMS‐b‐PBs) produced from living anionic polymerization (LAP). By the principle of modular functionalization, it is demonstrated that mono‐functionalized (PVPDMS‐g‐LC1)‐b‐PB and PS‐b‐(PB‐g‐LC2) not only maintain independence but also have cooperative contributions to bi‐functionalized (PVPDMS‐g‐LC1)‐b‐(PB‐g‐LC2) in terms of mesomorphic performances and microphase separation, which is evident from differential scanning calorimetry (DSC) and polarized optical morphologies (POM) and identified by powder X‐ray diffractions. With the application of the new principle of modular functionalization, local‐crosslinked liquid crystalline networks (LCNs) with controlled functionality are successfully synthesized, which show well‐controlled phase behaviors over molecular compositions.
Stepwise Oxidations in a Cofacial Copper(II) Porphyrin Dimer: Through‐Space Spin‐Coupling and Interplay between Metal and Radical Spins
Authors: Kumar Amit , Sanfui Sarnali , Sciortino Giuseppe , Maréchal Jean‐Didier , Garribba Eugenio , Rath Sankar Prasad
Published: March 2020

cis and trans‐copper(II) porphyrin dimers have been synthesized, in which two CuII porphyrin macrocycles are bridged through a rigid ethene linker for possible through‐space and through‐bond spin‐couplings between the paramagnetic CuII centers. It has been found that the two macrocycles come closer after 1 e− oxidation, however, they move far apart upon further 1 e− oxidation leading to transformation of the cis to the trans isomer. Detailed investigations are performed here on the interactions between the two porphyrin macrocycles, between two unpaired spins of closely spaced CuII centers, and also between the unpaired spins of metal and porphyrin π–cation radicals. Spectroscopic investigations along with the X‐ray structure of the 2 e−‐oxidized complex displayed strong electronic communications through the bridge between two porphyrin π–cation radicals. The counterion I9− is stabilized in an unusual trigonal‐pyramidal structure in the 2 e−‐oxidized complex in which the central iodide ion is bound with four iodine (I2) molecules. Variable‐temperature magnetic study revealed strong antiferromagnetic coupling between the two porphyrin π–cation radical spins (Jr–r) in the 2 e−‐oxidized complex. DFT calculations suggest stabilization of the triplet state, which is also in good agreement with the experiment. Ab initio molecular dynamics allowed the variation of the structural details to be followed upon stepwise oxidations and also the final isomerization process including its associated energy barrier.
Evidence for Electron Transfer between Graphene and Non‐Covalently Bound π‐Systems
Authors: Brülls Steffen M. , Cantatore Valentina , Wang Zhenping , Tam Pui Lam , Malmberg Per , Stubbe Jessica , Sarkar Biprajit , Panas Itai , Mårtensson Jerker , Eigler Siegfried
Published: March 2020

Hybridizing graphene and molecules possess a high potential for developing materials for new applications. However, new methods to characterize such hybrids must be developed. Herein, the wet‐chemical non‐covalent functionalization of graphene with cationic π‐systems is presented and the interaction between graphene and the molecules is characterized in detail. A series of tricationic benzimidazolium salts with various steric demand and counterions was synthesized, characterized and used for the fabrication of graphene hybrids. Subsequently, the doping effects were studied. The molecules are adsorbed onto graphene and studied by Raman spectroscopy, XPS as well as ToF‐SIMS. The charged π‐systems show a p‐doping effect on the underlying graphene. Consequently, the tricationic molecules are reduced through a partial electron transfer process from graphene, a process which is accompanied by the loss of counterions. DFT calculations support this hypothesis and the strong p‐doping could be confirmed in fabricated monolayer graphene/hybrid FET devices. The results are the basis to develop sensor applications, which are based on analyte/molecule interactions and effects on doping.
Controlled Assembly of Cu/Co‐Oxide Beaded Nanoclusters on Thiolated Graphene Oxide Nanosheets for High‐Performance Oxygen Evolution Catalysts
Authors: Munir Akhtar , ul Haq Tanveer , Hussain Iqtidar , Ullah Irfan , Hussain Syed Zajif , Qurashi Ahsanulhaq , Iqbal Javed , Rehman Asma , Hussain Irshad
Published: March 2020

The use of water splitting modules is highly desired for the sustainable production of H2 as a future energy carrier. However, the sluggish kinetics and demand of high anodic potential are the bottlenecks for half‐the cell oxygen evolution reaction (OER), which severely hamper the overall conversion efficiency. Although transition metal oxides based electrocatalysts have been envisioned as cost‐effective and potential contenders for this quest, nevertheless, their low conductivity, instability, and limited number of active sites are among the common impediments that need to be addressed to eventually enhance their inherent catalytic potential for enhanced OER activity. Herein, the controlled assembly of transition metal oxides, that is, Cu@CuOx nanoclusters (NCs, ≈2 nm) and Co@CoOx beaded nanoclusters (BNCs, ≈2 nm), on thiol‐functionalized graphene oxide (G‐SH) nanosheets is reported to form novel and highly efficient electrocatalysts for OER. The thiol (‐SH) functionality was incorporated by selective epoxidation on the surface of graphene oxide (GO) to achieve chemically exfoliated nanosheets to enhance its conductivity and trapping ability for metal oxides in nanoscale dimensions (≈2 nm). During the electrocatalytic reaction, overpotentials of 290 mV and 310 mV are required to achieve a current density of 10 mA cm−2 for BNCs and NCs, respectively, and the catalysts exhibit tremendous long‐term stability (≈50 h) in purified alkaline medium (1 m KOH) with no dissolution in the electrolyte. Moreover, the smaller Tafel slopes (54 mV/dec for BNCs and 66 mV/dec for NCs), and a Faradic efficiency of approximately 96 % indicate not only the selectivity but also the tailored heterogeneous electrons transfer (HET) rate, which is required for fast electrode kinetics. It is anticipated that such ultrasmall metal oxide nanoclusters and their controlled assembly on a conducting surface (G‐SH) may offer high electrochemical accessibility and a plethora of active sites owing to the drastic decrease in dimensions and thus can synergistically ameliorate the challenging OER process.
Gold‐Catalyzed Cycloisomerization of Sulfur Ylides to Dihydrobenzothiepines
Authors: Knittl‐Frank Christian , Saridakis Iakovos , Stephens Thomas , Gomes Rafael , Neuhaus James , Misale Antonio , Oost Rik , Oppedisano Alberto , Maulide Nuno
Published: March 2020

The metal‐promoted nucleophilic addition of sulfur ylides to π‐systems is a well‐established reactivity. However, the driving force of such transformations, elimination of a sulfide moiety, entails stoichiometric byproducts making them unfavorable in terms of atom economy. In this work, a new take on sulfur ylide chemistry is reported, an atom‐economical gold(I)‐catalyzed synthesis of dihydrobenzo[b]thiepines. The reaction proceeds under mild conditions at room temperature.
Synthesis of Well‐Defined High‐Valent Palladium Complexes by Oxidation of Their Palladium(II) Precursors
Authors: Zhang Bo , Yan Xuechao , Guo Shuai
Published: March 2020

The last decade has witnessed the rapid development of high‐valent Pd‐involved organic transformations. This has also led to a steadily growing number of publications concerning the preparation of isolable and characterizable palladium(III) and palladium(IV) complexes. A variety of one‐electron and two‐electron oxidants have been employed to give access to high‐oxidation‐state Pd compounds. Undoubtedly, the study of these stoichiometric reactions has great implications for relevant Pd‐mediated catalysis. In this minireview, the focus is on the synthetic approaches to structurally determined PdIII/IV complexes starting from their PdII precursors, and the advances in this research area from early 2010 to late 2019 will be highlighted. Chemical oxidations exploiting various oxidizing agents including 1) hypervalent iodine reagents; 2) halogens; 3) electrophilic fluorination reagents; 4) alkyl/aryl halides; 5) ferrocenium salts; 6) peroxides/O2; 7) sulfonyl chlorides; and 8) others are covered. A “greener” electrooxidation manner has also been reviewed.
Investigation on effects of adapting chromaticities and luminance on color appearance on computer displays using memory colors
Authors: Zhu Yuechen , Wei Minchen , Luo Ming R.
Published: March 2020

CAT02, the most widely used chromatic adaptation transform to characterize the chromatic adaptation mechanism in the human visual system, includes a factor D to characterize the degree of chromatic adaptation. This factor, however, is only determined by the luminance level of the adapting field and surround. This study was designed to investigate how the change of adapting chromaticities and the simultaneous changes of adapting chromaticities and luminance affect the degree of chromatic adaptation and color appearance on computer displays. The human observers adjusted the color appearance of various familiar objects and cubes on different display backgrounds. A higher degree of chromatic adaptation was found when using familiar objects, which was likely due to the cognitive mechanism. Both the adapting chromaticities and luminance significantly affected the degree of chromatic adaptation, with a lower degree under an adapting condition with a lower adapting correlated color temperature and a lower adapting luminance. In addition, the effect of adapting luminance on colorfulness (known as the Hunt Effect) was likely to be overpredicted in CAM02‐UCS, which merits further investigations.