bluuebunny/crossref_metadata_2025 huggingface dataset:
In‐Plane Magnetic Field‐Driven Creation and Annihilation of Magnetic Skyrmion Strings in Nanostructures
Authors: Mathur Nitish , Yasin Fehmi S. , Stolt Matthew J. , Nagai Takuro , Kimoto Koji , Du Haifeng , Tian Mingliang , Tokura Yoshinori , Yu Xiuzhen , Jin Song
Published: January 2021

In bulk chiral crystals, 3D structures of magnetic skyrmions form topologically protected skyrmion strings (SkS) that have shown potential as magnonic nano‐waveguides for information transfer. Although SkS stability is expected to be enhanced in nanostructures of skyrmion‐hosting materials, experimental observation and detection of SkS in nanostructures under an applied in‐plane magnetic field is difficult. Here, temperature‐dependent magnetic field‐driven creation and annihilation of SkS in B20 FeGe nanostructures (nanowires and nanoplates) under in‐plane magnetic field (H||) are shown and the mechanisms behind these transformations are explained. Unusual asymmetric and hysteretic magnetoresistance (MR) features are observed but previously unexplained during magnetic phase transitions within the SkS stability regime when H|| is along the nanostructure's long edge, which increase the sensitivity of MR detection. Lorentz transmission electron microscopy of the SkS and other magnetic textures under H|| in corroboration with the analysis of the anisotropic MR responses elucidates the field‐driven creation and annihilation processes of SkS responsible for such hysteretic MR features and reveals an unexplored stability regime in nanostructures.
A General Strategy for Antimony‐Based Alloy Nanocomposite Embedded in Swiss‐Cheese‐Like Nitrogen‐Doped Porous Carbon for Energy Storage
Authors: Yang Tao , Zhong Jiasong , Liu Jianwen , Yuan Yongjun , Yang Dexin , Mao Qinan , Li Xinyue , Guo Zaiping
Published: January 2021

Due to its suitable working voltage and high theoretical storage capacity, antimony is considered a promising negative electrode material for lithium‐ion batteries (LIBs) and has attracted widespread attention. The volume effect during cycling, however, will cause the antimony anode to undergo a severe structural collapse and a rapid decrease in capacity. Here, a general in situ self‐template‐assisted strategy is proposed for the rational design and preparation of a series of MSb (M = Ni, Co, or Fe) nanocomposites with MNC coordination, which are firmly anchored on Swiss‐cheese‐like nitrogen‐doped porous carbon as anodes for LIBs. The large interface pore network structure, the introduction of heteroatoms, and the formation of strong metalNC bonds effectively enhance their electronic conductivity and structural integrity, and provide abundant interfacial lithium storage. The experimental results have proved the high rate performance and excellent cycling stability of antimony‐based composite materials. Electrochemical kinetics studies have demonstrated that the increase in capacity during cycling is mainly controlled by the diffusion mechanism rather than the pseudocapacitance contribution. This facile strategy can provide a new pathway for low‐cost and high‐yield synthesis of Sb‐based composites with high performance, and is expected to be applied in other energy‐related fields such as sodium‐/potassium‐ion batteries or electrocatalysis.
Magnetothermal Miniature Reactors Based on Fe3O4 Nanocube‐Coated Liquid Marbles
Authors: Li Hualin , Liu Peng , Gunawan Renardi , Simeneh Zemenu Mengistie , Liang Chen , Yao Xi , Yang Mengsu
Published: January 2021

Liquid marbles have recently attracted much interest in various scientific fields because of their isolated environment and robustness. However, conventional liquid marbles lack a reliable heating mechanism, which is critical in many potential applications. Here, the development of iron oxide (Fe3O4) nanocube‐coated liquid marbles (iNLMs), which can be homogeneously heated with an alternating magnetic field (AMF) to as high as 86 °C, is reported. Through tuning the power of the AMF, the iNLMs canbe heated to desired temperatures in controllable patterns. Furthermore, multicenter and selective heating is realized based on the unique magnetothermal properties of iNLMs. As heatable miniature reactors, the iNLMs are further demonstrated to facilitate the kinetic study of temperature‐dependent chemical reactions. DNA amplification is successfully performed in liquid marbles, achieving a 25% superior amplification rate compared with that in a common thermal cycler. These results confirm the feasibility of coating liquid marbles with Fe3O4 nanocubes to form delicate magnetothermal miniature reactors, which provides a reliable method of applying liquid marbles in areas such as biosensor technology, point‐of‐care testing, and theranostics.
Electronic Conductive Inorganic Cathodes Promising High‐Energy Organic Batteries
Authors: Mao Minglei , Wang Shu , Lin Zejing , Liu Tao , Hu Yong‐Sheng , Li Hong , Huang Xuejie , Chen Liquan , Suo Liumin
Published: January 2021

The electrochemical utilization of organic electrode materials (OEMs) is highly dependent on an excess amount of inactive carbon at the expense of low packing density and energy density. In this work, the challenges by substituting inactive carbon with electronic conductive inorganic cathode (ECIC) materials, which are endowed with high electronic conductivity to transport electrons for redox reactions of the whole electrodes, high ion‐storage capacity to act as secondary active materials, and strong affinity with OEMs to inhibit their dissolution, are addressed. Combining representative ECICs (TiS2 and Mo6S8) with organic electrode materials (perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) and hexaazatrinaphthalene (HATN)) simultaneously achieves high capacity, low porosity, lean electrolyte, and thus high energy density. High gravimetric and volumetric energy densities of 153 Wh kg−1 and 200 Wh L−1 are delivered with superior cycling stability in a 30 mA h‐level Li/PTCDA‐TiS2 pouch cell. The proof‐of‐concept of organic–ECIC electrodes is also successfully demonstrated in monovalent Na, divalent Mg, and trivalent Al batteries, indicating their feasibility and generalizability. With the discovery of more ECIC materials and OEMs, it is anticipated that the proposed organic–ECIC system can result in further improvements at cell level to compete with transition metal‐based Li‐ion batteries.
Great Location: About Effects of Surface Bound Neighboring Groups for Passive and Active Fine‐Tuning of CO2 Adsorption Properties in Model Carbon Capture Materials
Authors: Klinkenberg Nele , Kraft Sophia , Polarz Sebastian
Published: January 2021

Improved carbon capture materials are crucial for managing the CO2 level in the atmosphere. The past focus was on increasing adsorption capacities. It is widely known that controlling the heat of adsorption (ΔHads) is equally important. If it is too low, CO2 uptake takes place at unfavorable conditions and with insufficient selectivity. If it is too high, chemisorption occurs, and the materials can hardly be regenerated. The conventional approach for influencing ΔHads is the modification of the adsorbing center. This paper proposes an alternative strategy. The hypothesis is that fine‐tuning of the molecular environment around the adsorbing center is a powerful tool for the adjustment of CO2‐binding properties. Via click chemistry, any desired neighboring group (NG) can be incorporated on the surfaces of the nanoporous organosilica model materials. Passive NGs induce a change in the polarity of the surface, whereas active NGs are capable of direct interaction with the active center/CO2 pair. The effects on ΔHads and on the selectivity are studied. A situation can be realized which resembles frustrated Lewis acid–base pairs, and the investigation of the binding‐species by solid‐state NMR indicates that the push–pull effects could play an essential role not only in CO2 adsorption but also in its activation.
Energy Harvesters for Wearable Electronics and Biomedical Devices
Authors: Hasan Md. Nazibul , Sahlan Shafishuhaza , Osman Khairuddin , Mohamed Ali Mohamed Sultan
Published: January 2021

Energy harvesters (EHs) are widely used to transform ambient energy sources into electrical energy, and have tremendous potential to power wearables electronics and biomedical devices by eliminating, or at least increasing, the battery life. Nevertheless, the use of EHs for a specific application depends on various aspects including the form of energy source, the structural configuration of the device, and the properties of materials. This paper presents a comprehensive review of the classification of EHs, notably thermoelectric generators (TEGs), triboelectric nanogenerators (TENGs), and piezoelectric generators (PEGs) that allows a wide variety of devices to be operated. The EHs are discussed in terms of their operating principles, optimization factors, state‐of‐the‐art materials, and device structure, that directly influence their operational efficiency. Besides, the breakthrough performance of each of the EHs listed above is highlighted. From the review and analysis, the maximum output power density of 9.2 mW cm−2, 50 mW cm−2, and 64.9 µW cm−2, respectively, are obtained from the TEG, TENG, and PEG, respectively. Furthermore, recent applications relevant to a specific EH and their output performance, are also enlightened. Eventually, the essential outcomes and future direction from this review are discussed and encapsulated.
Multifunctional Metasurface Design with a Generative Adversarial Network
Authors: An Sensong , Zheng Bowen , Tang Hong , Shalaginov Mikhail Y. , Zhou Li , Li Hang , Kang Myungkoo , Richardson Kathleen A. , Gu Tian , Hu Juejun , Fowler Clayton , Zhang Hualiang
Published: January 2021

Metasurfaces have enabled precise electromagnetic (EM) wave manipulation with strong potential to obtain unprecedented functionalities and multifunctional behavior in flat optical devices. These advantages in precision and functionality come at the cost of tremendous difficulty in finding individual meta‐atom structures based on specific requirements (commonly formulated in terms of EM responses), which makes the design of multifunctional metasurfaces a key challenge in this field. In this paper, a generative adversarial network that can tackle this problem and generate meta‐atom/metasurface designs to meet multifunctional design goals is presented. Unlike conventional trial‐and‐error or iterative optimization design methods, this new methodology produces on‐demand free‐form structures involving only a single design iteration. More importantly, the network structure and the robust training process are independent of the complexity of design objectives, making this approach ideal for multifunctional device design. Additionally, the ability of the network to generate distinct classes of structures with similar EM responses but different physical features can provide added latitude to accommodate other considerations such as fabrication constraints and tolerances. The network's ability to produce a variety of multifunctional metasurface designs is demonstrated by presenting a bifocal metalens, a polarization‐multiplexed beam deflector, a polarization‐multiplexed metalens, and a polarization‐independent metalens.
Hydrogel Microsphere Encapsulation Enhances the Flow Properties of Monoclonal Antibody Crystal Formulations
Authors: Schieferstein Jeremy M. , Reichert Paul , Narasimhan Chakravarthy N. , Yang Xiaoyu , Doyle Patrick S.
Published: January 2021

Monoclonal antibodies are therapeutic molecules known for their high specificity and versatility in the treatment of cancer and autoimmune disorders, but dosage forms are typically limited to low concentrations and large fluid volumes due to formulation challenges. Hydrogel microsphere formulations offer a route to quicker, patient‐friendly dosing regimens for monoclonal antibodies with high loading and favorable flow properties needed for injection through a narrow syringe needle under moderate applied force. Crystals of an intact monoclonal antibody are prepared as a concentrated suspension (>300 mg mL−1) which is then encapsulated within hydrogel microspheres with diameters as small as 30 µm. The hydrogel microspheres contain up to 56 wt% (dry basis) monoclonal antibody and release within 4 days under in vitro dissolution conditions. The hydrogel microspheres are concentrated into densely packed suspensions containing up to 300 mg mL−1 monoclonal antibody to evaluate their flow. These hydrogel formulations shear‐thin and have lower viscosity when compared to both liquid and suspended crystal forms of the monoclonal antibody, demonstrating the potential of hydrogel microsphere encapsulants as a carrier which can mask undesirable flow properties of concentrated antibody therapeutics.
Targeting Glioblastoma Using a Novel Peptide Specific to a Deglycosylated Isoform of Brevican
Authors: von Spreckelsen Niklas , Fadzen Colin M. , Hartrampf Nina , Ghotmi Yarah , Wolfe Justin M. , Dubey Shipra , Yang Bo Yeun , Kijewski Marie F. , Wang Shuyan , Farquhar Charlotte , Bergmann Sonja , Zdioruk Mykola , Wasserburg J. Roscoe , Scott Benjamin , Murrell Emily , Bononi Fernanda C. , Luyt Leonard G. , DiCarli Marcelo , Lamfers Martine L. M. , Ligon Keith L. , Chiocca E. Antonio , Viapiano Mariano S. , Pentelute Bradley L. , Lawler Sean E. , Cho Choi‐Fong
Published: January 2021

Glioblastoma (GBM) is the most common and deadliest form of brain tumor and remains amongst the most difficult cancers to treat. Brevican (Bcan), a central nervous system (CNS)‐specific extracellular matrix protein, is upregulated in high‐grade glioma cells, including GBM. A Bcan isoform lacking most glycosylation, dg‐Bcan, is found only in GBM tissues. Here, dg‐Bcan is explored as a molecular target for GBM. In this study, a d‐peptide library is screened to identify a small 8‐amino acid dg‐Bcan‐Targeting Peptide (BTP) candidate, called BTP‐7 that binds dg‐Bcan with high affinity and specificity. BTP‐7 is preferentially internalized by dg‐Bcan‐expressing patient‐derived GBM cells. To demonstrate GBM targeting, BTP‐7 is radiolabeled with 18F, a radioisotope of fluorine, and increased radiotracer accumulation is found in intracranial GBM established in mice using positron emission tomography (PET) imaging. dg‐Bcan is an attractive molecular target for GBM, and BTP‐7 represents a promising lead candidate for further development into novel imaging agents and targeted therapeutics.
Modeling Sorption and Diffusion of Alkanes, Alkenes, and their Mixtures in Silicalite: From MD and GCMC Molecular Simulations to Artificial Neural Networks
Authors: Gurras Arsenios , Gergidis Leonidas N.
Published: January 2021

Molecular dynamics (MD) in canonical (NVT) statistical ensemble and grand canonical‐Monte Carlo (GCMC) simulations along with artificial neural network (ANN) techniques are used for the study of diffusion and sorption characteristics of small alkanes, alkenes, and their mixtures in silicalite. In particular, sorption isotherms and self‐diffusion coefficients of alkanes (ethane to hexane), alkenes (ethene to hexene), and the respective alkane–alkene mixtures (consisting of the same number of carbon atoms) in silicalite are studied. The findings are directly compared with recent magic‐angle spinning pulsed field‐gradient nuclear magnetic resonance experimental diffusivity measurements and are in close agreement. Furthermore, new results are provided for the alkane–alkene systems. The sorption data from GCMC simulations, the self‐diffusivity calculations from the MD simulations along with available experimental data are used for the development of ANN predictive modeling procedures in order to give generic sorption and diffusion predictions for pure alkanes, alkenes in different input values of fugacity, temperature, and sorbate loadings at the minimum computational resources and time. Finally, structural characteristics for pure alkane, alkenes, and alkane–alkene mixtures when confined in the silicalite framework are computed revealing sorption domains and siting preferences.
Surface‐Bound Domain Penetration and Large Wall Current
Authors: Jiang Jun , Wang Chao , Chai Xiaojie , Zhang Qinghua , Hou Xu , Meng Fanqi , Gu Lin , Wang Jie , Jiang An Quan
Published: January 2021

By controlling the domain nucleation in ferroelectric mesa‐like cells formed at the surfaces of X‐cut LiNbO3 single‐crystal films that are integrated with Si substrates, growth of a surface‐bound needle‐like domain is observed in a quarter‐ellipsoidal shape. This domain, which extends in the major polar direction, contracts into several equilibrium segments with unequal lengths after removal of the in‐plane applied electric fields. The curved wall region located near the domain tip that connects the two top nanoelectrodes exhibits 12‐fold magnification of the on‐current when compared with the straight wall region near the tail. The field‐dependent flexible domain length and the high electrical conduction in the tip region promote crossbar integration of high‐density multilevel information‐storing memory devices and selectors with sufficient readout currents, thus enabling data‐intensive applications to be performed using domain wall microelectronics.
A New Functional Composite for Photovoltaic and Sensor Applications
Authors: Ghosh Puja , Roy Anurag , Mukhopadhyay Soumita , Narjinary Mousumi , Sundaram Senthilarasu , Sen Shrabanee , Devi Parukuttyamma Sujatha
Published: January 2021

As a preliminary drive to eventually develop dye‐sensitized solar cell (DSSC)‐powered gas sensors, many oxide‐based systems have been explored to fabricate sensors that can show response at room temperature for any analyte gas. As an outcome of recent work in this endeavor, a composite nanorod of anatase TiO2 with Na0.23TiO2 is found to exhibit both photovoltaic performance and gas sensing at room temperature as demonstrated here. An interesting morphology change along with a phase change from nanoparticle to nanorod is observed during the hydrothermal synthesis of anatase TiO2 nanoparticles with sodium hydroxide under a highly basic condition. In order to understand the effect of the minor phase Na0.23TiO2 on the inherent properties of anatase TiO2, the application of nanorod composite in two unique potential application areas, DSSC and acetone sensings is investigated. The composite material exhibits an enhanced efficiency of 7.85% for a DSSC. Surprisingly, a resistive sensor fabricated with the synthesized composite material exhibits room temperature p‐type sensing behavior toward different concentrations of acetone (10, 5, 3, 2, and 1 ppm) with high selectivity.
Au‐Promoted Pt nanoparticles supported on MgO/SBA‐15 as an efficient catalyst for selective oxidation of glycerol
Authors: Liu Yibin , Zha Minghao , Qin Hansong , Yao Shuang , Zhou Xin , Zhao Siming , Sheng Nan , Sun Yinghao , Jin Xin , Yan Hao , Feng Xiang , Chen Xiaobo , Yang Chaohe
Published: January 2021

A systematic study of Au‐promoted and unpromoted Pt/MgO/SBA‐15 catalyst is developed to separate the promoter effect from electron transfer effect between Au and Pt. Multi‐characterizations revealed that Au and Pt metals in these bimetallic catalysts mainly exist in the form of alloy, and the main role of Au is to reduce the size of AuPt alloy nanoparticles, thus enhancing the adsorption and activation of intermediate products. Through the optimization of various factors (including MgO content, Au/Pt molar ratio, reaction temperature and time), the Au1Pt2/MgO/SBA‐15 (0.05) catalyst exhibits excellent catalytic activity and glyceric acid selectivity for the selective oxidation of glycerol. Density functional theory calculation confirmed that the synergistic effect between Pt and Au active sites could facilitate the oxidation of primary hydroxyl group by promoting the activation of CH bond and the oxidation of aldehyde group. The results may give insights on designing effective Pt based bimetallic catalyst for selective oxidation of glycerol.
Quasi‐continuous synthesis of iron single atom catalysts via a microcapsule pyrolysis strategy
Authors: Huang Liyun , Wu Kui , He Qian , Xiong Chao , Gan Tao , He Xiaohui , Ji Hongbing
Published: January 2021

Single atom catalysts (SACs), featured with atomically dispersed metal species, have been considered as one of the most promising catalytic materials because of the excellent performance in various high‐value‐added reactions. However, the large‐scale and continuous‐type production of such SACs is still challenging. Herein, a novel and facile microcapsule strategy for the quasi‐continuous synthesis of iron SACs supported on S, N co‐doped carbon (Fe/SNC) is developed, and the Fe species are presented as isolated active sites and stabilized as the FeN3S‐like structure. The as‐prepared Fe/SNC catalysts exhibit excellent catalytic properties for selective oxidation of arylalkanes, which followed pseudo‐first‐order kinetics with an Ea = 41.5 kJ/mol. More importantly, the two Fe/SNC catalysts synthesized at different continuous times showed essentially identical catalyst structure and catalytic performance, demonstrating the superior reliability of our microcapsule strategy for the quasi‐continuous production of SACs, which can be easily scaled up to industrial application.
Contact Charge Transfer between Nominally Identical Materials
Authors: Angus John C. , Greber Isaac
Published: January 2021

Differences in concentrations of excited electrons arising from geometry‐dependent differences in de‐excitation paths lead to differences in Fermi energies, which enable contact charge transfer between otherwise identical solids of different size. This model is used with a quasi‐equilibrium description of the Fermi energy to estimate a lower bound of the magnitude of charging of pairs of like particles and the charge distribution in groups of interacting like particles. The predictions agree with observed charge transfer directions between large and small particles and with the broad particle size range over which charging is observed. Estimates of charging are compared to available measurements, the breakdown limits of air, and the relative strengths of interparticle electrostatic and gravitational forces. The influence of particle size distribution on the charge distribution in groups of particles is examined.
Carbene‐Catalyzed Activation of Remote Nitrogen Atoms of (Benz)imidazole‐Derived Aldimines for Enantioselective Synthesis of Heterocycles
Authors: Yang Xing , Xie Yongtao , Xu Jun , Ren Shichao , Mondal Bivas , Zhou Liejin , Tian Weiyi , Zhang Xinglong , Hao Lin , Jin Zhichao , Chi Yonggui Robin
Published: January 2021

A new mode of carbene‐catalyzed heteroatom activation and asymmetric reactions is disclosed. The reaction starts with addition of a carbene catalyst to a (benz)imidazole‐derived aldimine substrate. Subsequent oxidation and proton transfer lead to the formation of a catalyst‐bound triaza‐diene as the key intermediate, in which the nitrogen atom at a site remote to the catalyst‐substrate bond is activated. This unusual triaza‐diene intermediate then undergoes highly enantioselective reactions with activated ketones through a concerted asynchronous pathway, as supported by mechanistic studies and preliminary density function theory calculation.
“NAD‐display”: Ultrahigh‐Throughput in Vitro Screening of NAD(H) Dehydrogenases Using Bead Display and Flow Cytometry
Authors: Lindenburg Laurens , Hollfelder Florian
Published: January 2021

NAD(H)‐utiliing enzymes have been the subject of directed evolution campaigns to improve their function. To enable access to a larger swath of sequence space, we demonstrate the utility of a cell‐free, ultrahigh‐throughput directed evolution platform for dehydrogenases. Microbeads (1.5 million per sample) carrying both variant DNA and an immobilised analogue of NAD+ were compartmentalised in water‐in‐oil emulsion droplets, together with cell‐free expression mixture and enzyme substrate, resulting in the recording of the phenotype on each bead. The beads’ phenotype could be read out and sorted for on a flow cytometer by using a highly sensitive fluorescent protein‐based sensor of the NAD+:NADH ratio. Integration of this “NAD‐display” approach with our previously described Split & Mix (SpliMLiB) method for generating large site‐saturation libraries allowed straightforward screening of fully balanced site saturation libraries of formate dehydrogenase, with diversities of 2×104. Based on modular design principles of synthetic biology NAD‐display offers access to sophisticated in vitro selections, avoiding complex technology platforms.
M(NH2SO3)2 (M=Sr, Ba): Two Deep‐Ultraviolet Transparent Sulfamates Exhibiting Strong Second Harmonic Generation Responses and Moderate Birefringence
Authors: Hao Xia , Luo Min , Lin Chensheng , Peng Guang , Xu Feng , Ye Ning
Published: January 2021

Over the last few decades, the development of each new nonlinear optical (NLO)‐active functional unit has led to the discoveries of a series of excellent NLO materials. In the present work, based on first‐principles studies, we identified a novel deep‐UV (DUV) NLO‐active functional unit, a non‐π‐conjugated group viz. (NH2SO3)−. By combining alkaline‐earth metals with (NH2SO3)− group, two DUV transparent NLO sulfamates, M(NH2SO3)2 (M=Sr, Ba) with superior optical properties including strong SHG responses (1.2 and 2.7 × KH2PO4 (KDP)), short UV cut‐off edge (<190 nm) and moderate birefringence (0.056@589.3 nm for Sr(NH2SO3)2) were successfully synthesized. Our work has provided not only two promising DUV transparent NLO crystals, but also an innovative non‐π‐conjugated unit for developing more DUV transparent NLO materials.
(3S,4S)‐N‐substituted‐3,4‐dihydroxypyrrolidines as ligands for the enantioselective Henry reaction
Authors: Rénio Márcia R.R. , Sousa Francisco J.P.M. , Tavares Nélia C.T. , Valente Artur J.M. , da Silva Serra M. Elisa , Murtinho Dina
Published: January 2021

The enantioselective Henry reaction is a very important and useful carbon–carbon bond forming reaction. The execution of this reaction requires the use of efficient chiral catalysts. In this work, in situ formed complexes ofN‐substituted dihydroxypyrrolidines, chiral ligands derived from L‐tartaric acid and amines, were evaluated as catalysts in the enantioselective Henry reaction. The results showed that the nature of theN‐substituent on the ligand significantly influences the outcome of the reaction. Best results were obtained using a Cu (II) complex of (3S,4S)‐N‐benzyl‐3,4‐dihydroxypyrrolidine, in the presence of DIPEA, for the reaction of aromatic aldehydes with nitromethane, at room temperature, originating products witherup to 92:8 (R:S) and conversions up to 96%. The interaction between the pyrrolidine ligand and the copper ion, in isopropanol, was followed by UV‐vis spectrophotometry, showing a 1:1 stoichiometry and a binding constant of 4.4. The results obtained will contribute to the design and development of more efficient chiral catalysts for this type of reaction.
Palladium Catalyzed Cascade Azidation/Carbonylation of Aryl Halides with Sodium Azide for the Synthesis of Amides
Authors: Qi Zhuang , Li Shan‐Shan , Li Lin , Qin Qi , Yang Li‐Miao , Liang Ying‐Kang , Kang Yun , Zhang Xiang‐Zhi , Ma Ai‐Jun , Peng Jin‐Bao
Published: January 2021

Amide synthesis is one of the most important transformations in organic chemistry due to their ubiquitous presence in our daily life. In this communication, a palladium catalyzed cascade azidation/carbonylation of aryl halides for the synthesis of amides was developed. Both iodo‐ and bromobenzene derivatives were transformed to the corresponding amides using PdCl2/xantphos as the catalyst system and sodium azide as the nitrogen‐source. The reaction proceeds via a cascade azidation/carbonylation process. A range of alkyl and halogen substituted amides were prepared in moderate to good yields.
Domain‐wise differentiation of Mycobacterium tuberculosis H37Rv hypothetical proteins: A roadmap to discover bacterial survival potentials
Authors: Beg Md Amjad , Hejazi Iram Iqbal , Thakur Sonu Chand , Athar Fareeda
Published: January 2021

Proteomic information revealed approximately 3,923 proteins in Mycobacterium tuberculosis H37Rv genome of which around ∼25% of proteins are hypothetical proteins (HPs). The present work comprises computational approaches to identify and characterize the HPs of M. tuberculosis that symbolize the putative target for rationale development of a drug or antituberculosis strategy. Proteins were primarily classified based on motif and domain information, which were further analyzed for the presence of virulence factors (VFs), determination of localization, and signal peptide/enzymatic cleavage sites. 863 HPs were found, and 599 HPs were finalized based on motifs, that is, GTP (525), Trx (47), SAM (14), PE‐PGRS (5), and CBD (8). 80 HPs contain virulence factor (VF), 24 HPs localized in membrane region, and 4 HPs contain signal peptide/enzymatic cleavage sites. The overall parametric study finalizes four HPs Rv0679c, Rv0906, Rv3627c, and Rv3811 that also comprise GTPase domain. Structure prediction, structure‐based function prediction, molecular docking and mutation analysis of selected proteins were done. Docking studies revealed that GTP and GTPase inhibitor (mac0182344) were docked with all four proteins with high affinities. In silico point mutation studies showed that substitution of aspartate with glycine within a GTPase motif showed the largest decrease in stability and pH differentiation also affects protein's stability. This analysis thus fixes a roadmap in the direction of finding potential target of this bacterium for drug development and enlightens the efficacy of GTP as a major regulator of Mycobacterial cellular pathways.
Role of neddylation in neurological development and diseases
Authors: He Xin , Zhu Ainong , Feng Jianguo , Wang Xiaobin
Published: January 2021

Neddylation, a posttranslational protein modification, refers to the specific conjugation of NEDD8 to substrates, which is of great significance to various biological processes. Besides members of the cullin protein family, other key proteins can act as a substrate for neddylation modification, which remarkably influences neurodevelopment and neurodegenerative diseases. Normal levels of protein neddylation contribute to nerve growth, synapse strength, neurotransmission, and synaptic plasticity, whereas overactivation of protein neddylation pathways lead to apoptosis, autophagy of neurons, and tumorigenesis. Furthermore, impaired neddylation causes neurodegenerative diseases. These facts suggest that neddylation may be a target for treatment of these diseases. This review focuses on the current understanding of neddylation function in neurodevelopment as well as neurodegenerative diseases. Meanwhile, the recent view that different level of neddylation pathway may contribute to the opposing disease progression, such as neoplasms and Alzheimer's disease, is discussed. The review also discusses neddylation inhibitors, which are currently being tested in clinical trials. However, potential drawbacks of these drugs are noted, which may benefit the development of new pharmaceutical strategies in the treatment of nervous system diseases.
Novel erythropoietin‐based therapeutic candidates with extra N‐glycan sites that block hematopoiesis but preserve neuroplasticity
Authors: Bürgi Milagros , Aparicio Gabriela Inés , Dorella Aquiles , Kratje Ricardo , Scorticati Camila , Oggero Marcos
Published: January 2021

Neurological disorders affect millions of people causing behavior‐cognitive disabilities. Nowadays they have no effective treatment. Human erythropoietin (hEPO) has been clinically used because of its neurotrophic and cytoprotective properties. However, the erythropoietic activity (EA) should be considered as a side effect. Some analogs like non‐sialylated EPO, carbamylated EPO, or EPO peptides have been developed showing different weaknesses: erythropoiesis preservation, low stability, potential immunogenicity, or fast clearance. Herein, we used a novel strategy that blocks the EA but preserves hEPO neurobiological actions. N‐glycoengineering was accomplished to add a new glycosylation site within the hEPO sequence responsible for its EA. hEPO‐derivatives were produced by CHO.K1 cells, affinity‐purified and functionally analyzed studying their in vitro and in vivo EA, their in vitro neuronal plasticity in hippocampal neurons and their neuroprotective action by rescuing hippocampal neurons from apoptosis. Muteins Mut 45_47 (K45 > N45 + N47 > T47), Mut 104 (S104 > N104), and Mut 151_153 (G151 > N151 + K153 > T153) lost their EA but preserved their neuroprotection activity and enhanced neuroplasticity more efficiently than hEPO. Interestingly, Mut 45_47 resulted in a promising candidate to explore as neurotherapeutic considering not only its biopotency but also its pharmacokinetic potential due to the hyperglycosylation.
Purification and Biological Activities of Enzymatically Degraded Sargassum fusiforme Polysaccharides
Authors: Jiang Hui , Yang Si‐Qi , Chakka Vara Prasad , Qian Wen‐Wen , Wei Xiao‐Yi , Zhu Qing , Zhou Tao
Published: January 2021

Enzymatic hydrolysate of the crude polysaccharide (SFP) extracted from Sargassum fusiforme was purified by column DEAE‐52 and Sephadex G‐100 to yield four components, namely, ESFP1, ESFP2, ESFP3 and ESFP4. These components were characterized by chemical composition assay, GC/MS, HPGPC, UV and FT‐IR techniques. The in vitro antioxidant activities of the four purified fractions were investigated by measuring their radical scavenging activity and reducing power. The results suggested that all the four components possess good antioxidant activities. Among them, ESFP1 was found to possess the strongest 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical and hydroxyl radical‐scavenging activity, and the greatest ferric reducing power. The immunomodulatory effect of these four polysaccharides was demonstrated by their ability to promote proliferation, and to enhance both phagocytic activity and NO release in a macrophage RAW264.7 model. The results revealed that the bioactivities of the polysaccharides are related to their molecular weight, and the uronic acid and sulfate contents.
FlavonoidC‐Glycosyltransferases: Function, Evolutionary Relationship, Catalytic Mechanism and Protein Engineering
Authors: Dai Longhai , Hu Yumei , Chen Chun‐Chi , Ma Lixin , Guo Rey‐Ting
Published: January 2021

C‐glycosylflavonoids are polyphenolic phytochemicals that are ubiquitously distributed in the plant kingdom and confer a wealth of health‐promoting benefits to human body. These compounds harbor one or more sugar moieties that are attached to various regions of the flavonoid scaffold through rigid C–C glycosidic bonds. The diverse structures ofC‐glycosylflavonoids are granted by the prominent reactions of flavonoidC‐glycosyltransferases (CGTs). This review gives an extensive overview of CGTs that are involved in the biosynthesis ofC‐glycosylflavonoids, focusing on their evolutionary relationship and substrate specificity. Furthermore, structural insights into the catalytic mechanism and protein engineering of flavonoid CGTs are summarized. This review provides an important guidance for identification of novel flavonoid CGTs, biosynthesis ofC‐glycosylflavonoids, and elucidation of the function‐structure relationship of flavonoid CGTs.
Dry Reforming of Methane over Ni/γ‐MgO Catalysts in a Coaxial Dielectric Barrier Discharge Reactor
Authors: Farshidrokh Zahra , Khani Mohammad Reza , Khodadadi Abbasali , Gharibi Mahtab , Shokri Babak
Published: January 2021

Dry reforming of methane (DRM) over Ni/γ‐MgO catalysts in a coaxial dielectric barrier discharge (DBD) reactor was investigated and compared with DRM without catalysts. Firstly, the catalysts Ni/MgO, Ni/5%CeO2/MgO, and Ni/7%CeO2/MgO were prepared, their characteristics were specified by X‐ray diffraction, and then, they were partially packed into the DBD reactor. Various parameters such as the discharge power, flow rate, and CH4/CO2 molar ratio were explored. The presence of catalysts in the plasma reactor increased the yield and selectivity of H2 and CO. Furthermore, the effect of a reduced catalyst (Ni/7%CeO2/MgO reduced in argon‐hydrogen plasma) was evaluated, showing that CH4 can be converted with activated catalyst without extra power. Activated Ni/7%CeO2/MgO alone was able to convert CH4 to over 99 % for 30 min after reduction.
Controllable chiral behavior of type‐II core/shell quantum dots adjusted by shell thickness and coordinated ligands
Authors: Shao Xiao , Zhang Tianyong , Li Bin , Wu Yue , Li Siyi , Wang Jingchao , Jiang Shuang
Published: January 2021

Chiral semiconductor nanomaterials induced by capped chiral ligands are of great interest for both theoretical studies and advanced applications. In this study, CdTe/CdSe quantum dots (QDs), defined as type‐II core/shell nanostructure, with the advantage of a good separation of holes and electrons are imparted chirality with L/D‐cysteine and L/D‐penicillamine molecules. Circular dichroism (CD) at exciton transitions from cysteine‐ and penicillamine‐capped QDs is different in shape and intensity. CD intensities decrease with increasing shell thickness from three monolayers to six monolayers, indicating a decreased hybridization degree between the holes in CdTe core and the electrons in chiral ligands. Elevated cysteine concentration leads to decreased g‐factor, probably due to an altered binding mode from tridentate to bidentate. Our observations provide further insights into the understanding of chiral phenomenon as well as optimized design and applications of chiral nanostructures.
Pyrolysis kinetics and activation thermodynamic parameters of exhausted coffee residue and coffee husk using thermogravimetric analysis
Authors: Mukherjee Alivia , Okolie Jude A. , Tyagi Ramani , Dalai Ajay K. , Niu Catherine
Published: January 2021

Exhausted coffee residue (ECR) and coffee husk (CH) are potential feedstock for energy production through thermochemical and biochemical conversion processes. Kinetic study of ECR and CH is essential for the design and optimization of different thermochemical conversion processes. In this study, four different iso‐conversional methods were employed in the estimation of the activation energy (EA) and pre‐exponential factor (A). The methods used includes Flynn‐Wall‐Ozawa (FWO), Kissinger‐Akahira‐Sunose (KAS), Kissinger's method, and the Friedman method. Data from the thermogravimetric/derivative thermogravimetric analysis (TGA/DTG) at varying heating rates of 5‐20°C/min in an inert environment were used in this study. It was observed that the heating rate influences the pyrolysis parameters such as peak temperature, maximum degradation rate and initial decomposition temperature. The activation energy for ECR using the FWO method was in the range of 62.3‐102.4 kJ · mol−1. Likewise, the KAS and Friedman methods yielded activation energy between 51.3‐93.3 kJ · mol−1 and 10.6‐122.7 kJ · mol−1, respectively. In addition, the activation energy calculated for CH using FWO, KAS, and Friedman methods were shown to range from 39.1‐140.6 kJ · mol−1, 27.7‐131.6 kJ · mol−1, and 24.9‐111.2 kJ · mol−1, respectively.
Do Drug‐likeness Rules Apply to Oral Prodrugs?
Authors: Protti Ícaro F. , Rodrigues Daniel R. , Fonseca Sofia K. , Alves Ricardo J. , de Oliveira Renata B. , Maltarollo Vinícius G.
Published: January 2021

This paper describes a comparative analysis of the physicochemical and structural properties of prodrugs and their corresponding drugs with regard to drug‐likeness rules. The dataset used in this work was obtained from the DrugBank. Sixty‐five pairs of prodrugs/drugs were retrieved and divided into the following categories: carrier‐linked to increase hydrophilic character, carrier‐linked to increase absorption, and bioprecursors. We compared the physicochemical properties related to drug‐likeness between prodrugs and drugs. Our results show that prodrugs do not always follow Lipinski's Rule of 5, especially as we observed 15 prodrugs with more than 10 hydrogen bond acceptors and 18 with a molecular weight greater than 500 Da. This fact highlights the importance of extending Lipinski's rules to encompass other parameters as both strategies (filtering of drug‐like chemical libraries and prodrug design) aim to improve the bioavailability of compounds. Therefore, critical reasoning is fundamental to determine whether a structure has drug‐like properties or could be considered a potential orally active compound in the drug‐design pipeline.
CAM20u: An extension of CAM16 for predicting the color appearance of unrelated colors
Authors: Gao Cheng , Li Changjun , Shi Keyu , Luo Ming R. , Pointer Michael R.
Published: January 2021

A comprehensive color appearance model should be capable of predicting color appearance under a wide range of viewing conditions, including related and unrelated colors. The current CAM16 model was designed to predict the appearance of related colors and is in the process of becoming a CIE recommendation, to replace the current CIECAM02 model. This article describes an extension of CAM16 (named CAM20u) for predicting the brightness, hue quadrature, amount‐of‐white, and colorfulness attributes of unrelated colors. Its performance, together with that of other unrelated models, was tested based on the three available datasets. The results show that the CAM20u model significantly outperforms the others, especially for colorfulness and amount‐of‐white.
A brief acceptance and commitment intervention for work‐related stress and burnout amongst frontline homelessness staff: A single case experimental design series
Authors: Reeve Andy , Moghaddam Nima , Tickle Anna , Young Dave
Published: January 2021

Purpose

Recent intervention research for burnout amongst those working in health and social care contexts has found acceptance and commitment therapy (ACT) interventions to be of use but has provided less clarity on the role of psychological flexibility (a key ACT construct). This study further evaluated the usefulness of ACT for burnout and work‐engagement and assessed the role of psychological flexibility in contributing to therapeutic change.

Procedure

A nonconcurrent multiple‐baseline across‐participants single‐case experimental design was used. Four participants were recruited from a homelessness organization in the East Midlands, England. The ACT‐intervention was split into three modules to reflect the three aspects of the ACT triflex, and the sequence of delivery was randomized for each participant in order to test the relationship between these aspects.

Findings

Support was found for the ACT intervention reducing exhaustion and increasing work‐engagement. Psychological Flexibility increased in all participants and was temporally related to increases in other outcome variables in some instances. Delivery of the intervention focussed on any given aspect of the ACT triflex could increase different domains of psychological flexibility.

Implications

This study adds to the growing body of research in favour of ACT interventions for burnout and adds to the understanding of psychological flexibility as a mediating variable.
Deuterium‐tritium fuel impact ignition in the presence of degenerate plasma
Authors: Pourhosseini Seddigheh , Ghasemizad Abbas , Rezaei Somayeh , Jafari Mohammad J.
Published: January 2021

The impact ignition model is proposed based on the collision of a deuterium‐tritium (DT) layer accelerated to high velocities in a conical target. Simple mechanism, low cost, high coupling efficiency, and lack of the need for Petawatt laser pulses are the prominent advantages of this model. However, an increase in the productivity of this ignition mechanism is an important issue. In this regard, in this paper, the idea of impact ignition using the plasma degeneracy mechanism has been investigated. For this purpose, first, the ignition energy gain and stopping power of the DT beam in pure and impure fuels, by employing both degenerate and non‐degenerate plasmas, have been examined numerically. Then, in order to assess the penetration depth and range of the incident beam, simulations have been carried out using a three‐dimensional (3D) Monte Carlo code for two states of degenerate and non‐degenerate pre‐compressed pure fuel. The results imply that the state of degeneracy causes an increase by about 63% in the energy gain of impact ignition. In addition, the degeneracy condition leads to an approximate enhancement of 60% in the energy deposition of the pure fuel and about 67% for the impure fuel, with a mixed density ratio of 1.5%; therefore, the range and penetration depth decrease significantly in comparison to the non‐degenerate one. This can be indicative of the increasing efficiency of impact ignition conditions in the presence of degenerate plasma. The results of the range for the pure fuel have also been confirmed by a 3D Monte Carlo simulation code.
Graph traversal aided detection in uplink MBM massive MIMO based on socio‐cognitive knowledge of swarm optimization
Authors: Datta Arijit , Bhatia Vimal , Mandloi Manish , Panda Ganapati
Published: January 2021

Media‐based modulation (MBM) plays a crucial role in enhancing the spectral efficiency and energy efficiency of massive MIMO (mMIMO) systems for 5G and beyond wireless communications. In MBM, multiple parasitic elements, also termed as radio frequency (RF) mirrors, are placed near the transmit antennas for generating different channel fade realizations. These realizations are obtained by ON/OFF switching of RF mirrors. One of those channel fade realizations is selected (using a part of the incoming information bits) for transmitting a part of the information bits utilizing a symbol chosen from the conventional constellation set (using another part of the incoming information bits). Transmission of a symbol through one of the available channel realizations constitutes a sparse transmit vector for each user in MBM‐mMIMO. The sparse nature of transmitted symbols from multiple users and inter‐user interference makes the symbol detection in uplink MBM‐mMIMO challenging. Therefore, in this article, the problem of symbol detection in MBM‐mMIMO is analyzed from a graph‐theoretical point of view, and a graph‐traversal aided low‐complexity symbol detection algorithm is proposed inspired by socio‐cognitive learning of swarm optimization. Also, the convergence characteristic of the proposed technique is investigated theoretically. Further, an analytical expression of upper bound on bit error rate performance is derived and corroborated through simulations. Viability and robustness of the proposed technique are also justified through simulations over state‐of‐art detection techniques, under both perfect and imperfect channel state information scenarios.