bluuebunny/crossref_metadata_2025 huggingface dataset:
Quarantine vs Social Consciousness: A Prediction to Control COVID-19 Infection
Authors: Mahmud Md. Shahriar , Kamrujjaman Md. , Jubyrea J. , Islam Md. Shahidul , Islam Md. Shafiqul
Published: May 2020

Background: The world is now in an emergency of preventing the drastic spread of COVID-19. After the infection was first reported in December 2019, almost every country did not pay attention to this highly contaminated disease and failed to react swiftly. Now the whole planet is in an vulnerable state, resulting to increase the mortality rate and facing difficulties in all socio-economic aspects. That is why we have the urge to develop an efficient mathematical model (quarantine) based on social consciousness to control the epidemic.

Methods: This is a quarantine mathematical model. The outcome of the system is dependent on social consciousness. We have calculated the awareness level by considering various socio-economic factor of each country. In our model, the parameters are Education Index, Gross Domestic Product (GDP) per capita, population density, high literacy and stable economy. To maximize the efficiency of the model, it has to be implemented in initial stage. However, strictapplication of the method in vigorous stage of epidemic will also bring a satisfactory outcome.

Results: In Spain, quarantine was effected on March 14, 2020. Spain experienced an increase in reported cases for 13 days of quarantine enforcement and from the 14th day, daily reported cases started to decrease with small fluctuation. Government ensured the social isolation through quarantine. After imposition of a quarantine on March 9, 2020 in Italy, within 13 days of lock-down, the maximum number of infection started to decrease. Similar results observed in France. Higher social consciousness would decrease the number of infected population dramatically while minimal or lower awareness will do a outburst.

Conclusion: Outbreak will be in control of health care system which yields to reduce the death rate and will ensure social and economic stability.
Seepage and Recharge under a Stream-aquifer Unsaturated Connection
Authors: Morel-Seytoux Hubert J.
Published: May 2020

Most widely used integrated hydrologic models use outdated descriptions of the stream-aquifer flow exchange. Understandably they do it for practical reasons to avoid computational costs in large-scale regional studies. In this article we propose a largely analytical technique that (1) describes the situation when the connection is unsaturated while avoiding a lot of numerical work and at the same time remains quite physical, (2) has the capability to describe fluctuations between saturated and unsaturated connections, and (3) can be coupled easily with the numerical groundwater model that describes what happens in the broad system of cells away from the river(s). Essentially two separate methods are compared for the purpose of selecting the most practical of the two.
Toxic Effect of Refinery Industrial Effluent Using Three Toxicity Bioassays
Authors: Egurefa Samson Ogagaoghene , Orji Micheal Uchenna , Uba Bright Obidinma
Published: May 2020

Aims: To determine the toxic effect of refinery industrial effluents using three toxicity bioassays.

Study Design: Five treatments and the controls designs were set up in triplicates containing 6.25%,12.5%, 25%, 50%, 100% and 0% of the industrial effluents and incubated at 24°C for 0 - 96 h. The five treatments and control set ups designated as PH, Warri and Control (Without effluent) were used to determine the toxic effect of industrial effluents.

Place and Duration of Study: Department of Microbiology, Faculty of Natural Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli Nigeria between September, 2019 and December, 2019.

Methodology: A laboratory scale study was carried on two composite samples of the produced water samples from the two studied areas using physicochemical analyses, microalgal toxicity test, mollusk toxicity and Zea mays test.

Results: The results revealed that Port Harcourt refinery effluent contains higher quantities of physicochemical parameters than the Warri effluent sample. Warri sample had the most harmful effects on Selenastrum capricornutum, Lymnaea stagnalis and Zea mays, with ErC50 values of 47.62%, LC50 of 51.86% and EC50 of-32.68%, respectively. Inhibition (%) and mortality (%) of all species used were found to be concentration dependent with a significant (P < 0.05) strong positive correlation at increasing concentrations of industrial effluents.

Conclusion: Thus, these raw industrial effluents from Port Harcourt and Warri refineries are toxic and induced growth inhibition, mortality and phytotoxicity and adequate measures should be taken by these industries to minimize their negative environmental impacts.
Nucleus‐to‐Plastid Phytochrome Signalling in Controlling Chloroplast Biogenesis
Authors: Yoo Chan Yul , Han Soeun , Chen Meng
Published: May 2020

The biogenesis of photosynthetically active chloroplasts in flowering plants (angiosperms) is initiated by light through the red and far‐red photoreceptors, phytochromes, which activate photosynthesis‐associated genes encoded by both the nuclear and plastid genomes. Because photoactivated phytochromes localize to the nucleus but not the plastids, phytochromes ought to control plastid transcription through nucleus‐to‐plastid or anterograde signalling. However, the mechanism of anterograde signalling remains poorly understood. Recent advances in our understanding of phytochrome signalling and plastid transcription led to the discovery of the framework of an anterograde signalling pathway, which links light‐dependent regulation of nuclear repressors of chloroplast biogenesis to the control of the assembly and activity of the bacterial‐type plastidial RNA polymerase for transcribing plastid‐encoded photosynthesis genes.

This article is aimed to gather and reanalyze the evidence in the literature relevant to the phytochrome control of chloroplast biogenesis to forge a model of anterograde signalling mechanisms for the regulation of plastid transcription by light.
Superhydrophilic Stainless Steel Mesh for Oil–Water Separation with Long‐Term Durability, Impressive Corrosion Resistance, and Abrasion Resistance
Authors: Sun Bin , Zhang Fengmei , Gao Min , Zhao Song , Wang Jiarou , Zhang Wen , Wang Zhi , Wang Jixiao
Published: May 2020

Durable properties of oil–water separation materials are challenging issue during the development from laboratory to practical application. Herein, twill woven stainless‐steel mesh is modified through oxidation and conversion steps, and applied for oil–water separation. The modified mesh displays excellent superhydrophilic property with water contact angle ≈0° and underwater oil contact angle up to 159°. Oil–water separation performance is evaluated using a series of oil–water mixtures. The results demonstrate that oil–water mixtures can be separated under gravity with oil rejection >99% and water permeate fluxes in the range of 40–60 k L m−2 h−1. Moreover, the modified mesh shows long‐term durability, excellent chemical corrosion resistance, abrasion resistance, and fouling resistance. It can maintain stable oil rejection and water flux even after 100 cycles separation for machine oil–water mixture, or after 300 days immersion in artificial seawater, or after 15 days immersion in corrosion acidic or alkaline solutions. Furthermore, the modified mesh exhibit impressive abrasion resistance that keep oil rejection >99% after 80 m abrasion under 1000 g. These excellent performances of the modified mesh are further explained from the special texture of twill woven stainless‐steel mesh and the formed water film due to its superhydrophilicity.
PEG/HA Hybrid Hydrogels for Biologically and Mechanically Tailorable Bone Marrow Organoids
Authors: Vallmajo‐Martin Queralt , Broguiere Nicolas , Millan Christopher , Zenobi‐Wong Marcy , Ehrbar Martin
Published: May 2020

Bone marrow (BM) organoids provide powerful tools to study the vital interplay between the BM microenvironment and resident cells. Current biomaterials, however, are limited in terms of versatility for independently studying the biochemical and biophysical properties that regulate BM function. Here, a transglutaminase (TG) crosslinked system that seamlessly incorporates poly(ethylene glycol) (PEG) and hyaluronic acid (HA) into hybrid hydrogels for the formation of BM analogues is presented. By combining features of PEG and HA, these novel biomaterials are tunable to optimize their physical and biological properties for BM organoid formation. Utility of the TG‐PEG/HA hybrid hydrogels to maintain, expand, or differentiate human bone marrow‐derived stromal cells and human hematopoietic stem and progenitor cells in vitro is demonstrated. Even more compelling, TG‐PEG/HA hybrid hydrogels are superior to currently used natural biomaterials in forming humanized BM organoids in a xenograft model. Hybrid hydrogels in comparison to pure PEG or pure HA afford the ideal attributes of both regarding material handling, structural integrity, and minimizing macrophage infiltration in vivo. The engineered humanized BM organoids presented here may be effective tools for the study of this intricate organ.
3D Printed Meta‐Helmet for Wide‐Angle Thermal Camouflages
Authors: Peng Yu‐Gui , Li Ying , Cao Pei‐Chao , Zhu Xue‐Feng , Qiu Cheng‐Wei
Published: May 2020

Thermal camouflage utilizes the manipulation of heat fluxes to conceal an arbitrary object in various environments from being detected via thermography. In the past decade, the field of thermal metamaterials and the technique of 3D printing have been rapidly developed, which makes nonintuitive heat flux manipulation feasible. However, when thermal metamaterials are applied to the thermal camouflaging, their conductivities are dependent on the properties of background, leading to the damage of background integrality. Moreover, previous thermal camouflaging schemes have mostly worked in the 2D regime, largely restricting their functional angles and application scenarios, especially in complex environments. Here, wide‐angle radiative thermal camouflaging is realized by using a 3D‐printed meta‐helmet of extremely anisotropic thermal conductivities. Based on 3D coordinate transformation, this meta‐helmet directly maps temperature distributions from the background to the metamaterial surface without damaging background integrity. The non‐invasive device is efficient in wide‐angle thermal camouflage by rendering the same emissivity to the background medium and can self‐adjust to various even unknown background thermal fields, which is demonstrated in numerical simulations and experiments. This work opens a door to the 3D transformation‐thermotics‐based devices for versatile practical applications in thermal infrared stealth of macro‐sized objects and others.
Guanidinium‐Assisted Surface Matrix Engineering for Highly Efficient Perovskite Quantum Dot Photovoltaics
Authors: Ling Xufeng , Yuan Jianyu , Zhang Xuliang , Qian Yuli , Zakeeruddin Shaik M. , Larson Bryon W. , Zhao Qian , Shi Junwei , Yang Jiacheng , Ji Kang , Zhang Yannan , Wang Yongjie , Zhang Chunyang , Duhm Steffen , Luther Joseph M. , Grätzel Michael , Ma Wanli
Published: May 2020

Metal halide perovskite quantum dots (Pe‐QDs) are of great interest in new‐generation photovoltaics (PVs). However, it remains challenging in the construction of conductive and intact Pe‐QD films to maximize their functionality. Herein, a ligand‐assisted surface matrix strategy to engineer the surface and packing states of Pe‐QD solids is demonstrated by a mild thermal annealing treatment after ligand exchange processing (referred to as “LE‐TA”) triggered by guanidinium thiocyanate. The “LE‐TA” method induces the formation of surface matrix on CsPbI3 QDs, which is dominated by the cationic guanidinium (GA+) rather than the SCN−, maintaining the intact cubic structure and facilitating interparticle electrical interaction of QD solids. Consequently, the GA‐matrix‐confined CsPbI3 QDs exhibit remarkably enhanced charge mobility and carrier diffusion length compared to control ones, leading to a champion power conversion efficiency of 15.21% when assembled in PVs, which is one of the highest among all Pe‐QD solar cells. Additionally, the “LE‐TA” method shows similar effects when applied to other Pe‐QD PV systems like CsPbBr3 and FAPbI3 (FA = formamidinium), indicating its versatility in regulating the surfaces of various Pe‐QDs. This work may afford new guidelines to construct electrically conductive and structurally intact Pe‐QD solids for efficient optoelectronic devices.
Localized Surface Plasmon Resonance Enhanced Light Absorption in AuCu/CsPbCl3 Core/Shell Nanocrystals
Authors: Gong Maogang , Alamri Mohammed , Ewing Dan , Sadeghi Seyed M. , Wu Judy Z.
Published: May 2020

Localized surface plasmon resonance (LSPR) is shown to be effective in trapping light for enhanced light absorption and hence performance in photonic and optoelectronic devices. Implementation of LSPR in all‐inorganic perovskite nanocrystals (PNCs) is particularly important considering their unique advantages in optoelectronics. Motivated by this, the first success in colloidal synthesis of AuCu/CsPbCl3 core/shell PNCs and observation of enhanced light absorption by the perovskite CsPbCl3 shell of thickness in the range of 2–4 nm, enabled by the LSPR AuCu core of an average diameter of 7.1 nm, is reported. This enhanced light absorption leads to a remarkably enhanced photoresponse in PNCs/graphene nanohybrid photodetectors using the AuCu/CsPbCl3 core/shell PNCs, by more than 30 times as compared to the counterparts with CsPbCl3 PNCs only (8–12 nm in dimension). This result illustrates the feasibility in implementation of LSPR light trapping directly in core/shell PNCs for high‐performance optoelectronics.
Efficient Nitrate Synthesis via Ambient Nitrogen Oxidation with Ru‐Doped TiO2/RuO2 Electrocatalysts
Authors: Kuang Min , Wang Yu , Fang Wei , Tan Huiteng , Chen Mengxin , Yao Jiandong , Liu Chuntai , Xu Jianwei , Zhou Kun , Yan Qingyu
Published: May 2020

A facile pathway of the electrocatalytic nitrogen oxidation reaction (NOR) to nitrate is proposed, and Ru‐doped TiO2/RuO2 (abbreviated as Ru/TiO2) as a proof‐of‐concept catalyst is employed accordingly. Density functional theory (DFT) calculations suggest that Ruδ+ can function as the main active center for the NOR process. Remarkably doping Ru into the TiO2 lattice can induce an upshift of the d‐band center of the Ru site, resulting in enhanced activity for accelerating electrochemical conversion of inert N2 to active NO*. Overdoping of Ru ions will lead to the formation of additional RuO2 on the TiO2 surface, which provides oxygen evolution reaction (OER) active sites for promoting the redox transformation of the NO* intermediate to nitrate. However, too much RuO2 in the catalyst is detrimental to both the selectivity of the NOR and the Faradaic efficiency due to the dominant OER process. Experimentally, a considerable nitrate yield rate of 161.9 µmol h−1 gcat−1 (besides, a total nitrate yield of 47.9 µg during 50 h) and a highest nitrate Faradaic efficiency of 26.1% are achieved by the Ru/TiO2 catalyst (with the hybrid composition of RuxTiyO2 and extra RuO2 by 2.79 wt% Ru addition amount) in 0.1 m Na2SO4 electrolyte.
Facile Synthesis of 2D Tin Selenide for Near‐ and Mid‐Infrared Ultrafast Photonics Applications
Authors: Wang Zhenhong , Li Feng , Guo Jia , Ma Chunyang , Song Yufeng , He Zhenwu , Liu Jun , Zhang Yupeng , Li Delong , Zhang Han
Published: May 2020

Tin selenide (SnSe) nanosheets, as 2D materials, exhibit many excellent optical and electronic properties and can be widely utilized in various potential applications, such as photodetectors, photovoltaic cells, optical sensors, and nonlinear optical devices. Herein, the 2D SnSe nanosheets are synthesized by the method combining lithium ion intercalation and sonication‐assisted liquid phase exfoliation. The morphology, structures, and chemical composition of as‐prepared 2D SnSe sample are systemically analyzed. Interestingly, the 2D SnSe nanosheets are successfully fabricated as a saturable absorber (SA) by depositing on a microfiber, which shows excellent nonlinear absorption property in a wide band. By incorporating SnSe‐based SA into the fiber lasers, stable mode‐locked pulses can be realized at 1.5 and 2 µm with a pulse duration of 0.542 and 2.12 ps, respectively. Additionally, harmonic mode locking of bound solitons is generated in the 1.5 µm fiber laser. Furthermore, dual‐wavelength mode‐locked pulses at 1897.3 and 1910.5 nm are also obtained in the 2 µm fiber laser. These results validate that 2D SnSe materials show great potential in nonlinear photonic devices for broadband ultrafast photonics.
Nanoscale Optical Display and Sensing Based on the Modification of Fano Lineshape
Authors: Xiang Jin , Chen Jingdong , Lan Sheng , Miroshnichenko Andrey E.
Published: May 2020

The shift of Fano resonances has been widely exploited to realize biomedical sensing, optical filtering, and optical switching. Here, the formation of Fano resonances in the scattering spectra of silicon nanoparticles excited by surface plasmon polaritons is reported and the modification of Fano lineshapes is demonstrated. It is revealed that the subradiant and superradiant modes responsible for the formation of Fano resonance originate from the coherent interaction of the electric and magnetic dipoles excited in the silicon nanoparticle with their mirror images induced by a thin metal film. The modification of the asymmetry parameter q can be realized by simply adjusting the angle of the incident light or by slightly varying the environment refractive index. The tuning of the q value is accompanied by the variation of the field enhancement factors and manifested in the color change of the scattered light. The strongest enhancement of both electric and magnetic fields can be achieved at the point of contact between the silicon nanoparticle and the metal film for the symmetric Fano lineshape (q ≈ 0). These findings indicate the potential applications of such a hybrid metal–dielectric system in sensing, color display, and strong light–matter interaction.
Super‐Soft DNA/Dopamine‐Grafted‐Dextran Hydrogel as Dynamic Wire for Electric Circuits Switched by a Microbial Metabolism Process
Authors: Han Jinpeng , Cui Yuchen , Han Xinpeng , Liang Chenyu , Liu Wenguang , Luo Dan , Yang Dayong
Published: May 2020

Engineering dynamic systems or materials to respond to biological process is one of the major tasks in synthetic biology and will enable wide promising applications, such as robotics and smart medicine. Herein, a super‐soft and dynamic DNA/dopamine‐grafted‐dextran hydrogel, which shows super‐fast volume‐responsiveness with high sensitivity upon solvents with different polarities and enables creation of electric circuits in response to microbial metabolism is reported. Synergic permanent and dynamic double networks are integrated in this hydrogel. A serials of dynamic hydrogel‐based electric circuits are fabricated: 1) triggered by using water as switch, 2) triggered by using water and petroleum ether as switch pair, 3) a self‐healing electric circuit; 4) remarkably, a microbial metabolism process which produces ethanol triggering electric circuit is achieved successfully. It is envisioned that the work provides a new strategy for the construction of dynamic materials, particularly DNA‐based biomaterials; and the electric circuits will be highly promising in applications, such as soft robotics and intelligent systems.
Clinical characteristics and esophageal motility in Sjögren's syndrome: A single‐center study in Taiwan
Authors: Lin Chun‐Yu , Wu Keng‐Liang , Yao Chih‐Chien , Tsai Cheng‐En , Tai Wei‐Chen , Liang Chih‐Ming , Chou Yeh‐Pin , Chuah Seng‐Kee
Published: May 2020

Sjögren's syndrome is an autoimmune disease that may cause inflammation of exocrine glands, including the salivary glands. Some patients with Sjögren's syndrome also have gastrointestinal disease, such as gastroesophageal reflux disease. A few studies have shown that an association might exist between Sjögren's syndrome and esophageal motility disorder, but the results have been inconsistent. This study aimed to investigate the relationships between clinical symptoms and esophageal motility function in patients with Sjögren's syndrome. Fifty‐six patients with suspected esophageal reflux or motility disease who had undergone esophagogastroduodenoscopy and esophageal manometry were retrospectively enrolled. Thirteen patients were diagnosed as having Sjögren's syndrome according to the American‐European Consensus Criteria. Forty‐three patients without any rheumatic disease or esophageal motor disorder were designated as the control group. We compared the clinical symptoms and endoscopic and esophageal manometric findings between the Sjögren's syndrome and the control groups. Acid regurgitation was more prevalent in the Sjögren's syndrome group (53.8%) than in the control group (11.6%) (P = .003), but the endoscopic findings of reflux esophagitis were similar in both groups (Sjögren's: 38.5%; control: 39.5%; P = .945). Barrett's esophagus was more prevalent in the Sjögren's syndrome group than in the control group (15.4% vs 0%, respectively; P = .051). The upper esophageal sphincter was shorter in the Sjögren's syndrome group than in the control group (2.38 ± 0.65 cm vs 3.07 ± 0.74 cm, respectively; P = .003). More reflux symptoms and distinct motility patterns were found in the Sjögren's syndrome group as compared with the control subjects.
Familial dilated cardiomyopathy associated with pathogenic TBX5 variants: Expanding the cardiac phenotype associated with Holt–Oram syndrome
Authors: Patterson Jenny , Coats Caroline , McGowan Ruth
Published: May 2020

Holt–Oram syndrome (HOS) is a rare, autosomal dominant disorder caused by heterozygous pathogenic variants in cardiac T‐box transcription factor, TBX5. Classically, it is associated with upper limb malformations and variable cardiac abnormalities. Limb manifestations are considered to be invariably present, ranging in severity from limitation in movement, to triphalangeal thumbs, absent thumbs, shortened forearms, or phocomelia. Cardiac involvement is characterized by congenital heart defects, most commonly septal structural malformations, and conduction system disease. Recently, novel TBX5 variants have also been reported in association with dilated cardiomyopathy (DCM). In this context, we report eight individuals from four unrelated families, in whom pathogenic variants in TBX5 segregated with an atypical HOS phenotype. Affected individuals exhibit relatively mild skeletal features of HOS, with a predominant cardiac phenotype, which includes several individuals affected by non‐ischaemic DCM. To our knowledge, these represent the first reported cases of DCM in families with skeletal features of HOS, some of whom also harbored variants previously linked to a classical HOS phenotype (p. Arg279* and p.Arg237Gln). This finding supports diverse roles of TBX5 in cardiovascular development and function, and confirms the importance of long‐term cardiac surveillance for individuals affected by HOS. Furthermore, these families highlight the wide phenotypic variability of HOS, which may include comparatively mild upper limb findings in respect to cardiac manifestations.
A Diselenide Turn‐On Fluorescent Probe for the Detection of Thioredoxin Reductase
Authors: Mafireyi Tendai J. , Laws Madeleine , Bassett John W. , Cassidy Pamela B. , Escobedo Jorge O. , Strongin Robert M.
Published: May 2020

We report the first diselenide‐based probe for the selective detection of thioredoxin reductase (TrxR), an enzyme commonly overexpressed in melanomas. The probe design involves conjugation of a seminaphthorhodafluor dye with a diselenide moiety. TrxR reduces the diselenide bond, triggering a fluorescence turn‐on response of the probe. Kinetic studies reveal favorable binding of the probe with TrxR with a Michaelis–Menten constant (Km) of 15.89 μm. Computational docking simulations predict a greater binding affinity to the TrxR active site in comparison to its disulfide analogue. In vitro imaging studies further confirmed the diselenide probe exhibited improved signaling of TrxR activity compared to the disulfide analogue.
Copper 1,19‐Diaza‐21,24‐dicarbacorrole: A Corrole Analogue with an N−N Linkage Stabilizes a Ground‐State Singlet Organocopper Species
Authors: Basumatary Biju , Hashiguchi Ikuho , Mori Shigeki , Shimizu Soji , Ishida Masatoshi , Furuta Hiroyuki
Published: May 2020

A copper complex of a heterocorrole analogue with an N–N linkage, 1,19‐diaza‐21,24‐dicarbadibenzocorrole (Cu‐5), was successfully synthesized via oxidative metalation–cyclization of a tetrapyrrolic precursor. The N–N linkage in the skeleton of Cu‐5, which serves as a mediator of π‐electron delocalization, features an 18π aromatic system. The electronic structure of Cu‐5 is best described as a ground‐state singlet species stabilized by the distinct NNCC coordination core. This finding shows how the ligand's design can be used to modulate the Cu
orbital energy, thereby making such compounds invaluable for copper‐based catalytic applications.
Three‐Dimensional Chemically Stable Covalent Organic Frameworks through Hydrophobic Engineering
Authors: Ma Yunchao , Wang Yujie , Li Hui , Guan Xinyu , Li Baoju , Xue Ming , Yan Yushan , Valtchev Valentin , Qiu Shilun , Fang Qianrong
Published: May 2020

The development of three‐dimensional (3D) covalent organic frameworks (COFs) with high chemical stability is of critical importance for their practical use. In this work, it is demonstrated that the stability of 3D COFs can be improved by periodic decoration of isopropyl groups on their backbones. Owing to the strong hydrophobicity of the alkyl groups, the resultant COFs show high crystallinity, permanent pores, and exceptional stability in harsh environments, such as strong acids (3 m HCl or 3 m H2SO4 for one week), a strong base (20 m NaOH for one week), and boiling water (100 °C for one month). Furthermore, these highly stable and hydrophobic COFs display excellent oil/water separation performance with >99 % separation efficiency over a wide pH range. This work demonstrates the use of alkyl decoration in 3D COFs to tune their chemical stability and expand their potential applications.
Facettierte verzweigte Nickel‐Nanopartikel mit variierbarer Verzweigungslänge für die hochaktive elektrokatalytische Oxidation von Biomasse
Authors: Poerwoprajitno Agus R. , Gloag Lucy , Watt John , Cychy Steffen , Cheong Soshan , Kumar Priyank V. , Benedetti Tania M. , Deng Chen , Wu Kuang‐Hsu , Marjo Christopher E. , Huber Dale L. , Muhler Martin , Gooding J. Justin , Schuhmann Wolfgang , Wang Da‐Wei , Tilley Richard D.
Published: May 2020

Die Kontrolle der Bildung von verzweigten Nanopartikeln mit hoher Homogenität ist eine der größten Herausforderungen bei der Herstellung von Nanokatalysatoren mit verbesserter Aktivität und Stabilität. Mithilfe eines Mechanismus unter Nutzung eines kubischen Kerns und hexagonaler Verzweigung zur Bildung hochgradig monodisperser verzweigter Nanopartikel wurde die Länge der Nickelverzweigungen variiert. Es hat sich gezeigt, dass die Verlängerung der Nickelzweige mit ihrer hohen Bedeckung der aktiven Facetten die Aktivität für die elektrokatalytische Oxidation von 5‐Hydroxymethylfurfural (HMF) als Beispiel für die Umwandlung von Biomasse verbessert.
Boosting Low‐Valent Aluminum(I) Reactivity with a Potassium Reagent
Authors: Grams Samuel , Eyselein Jonathan , Langer Jens , Färber Christian , Harder Sjoerd
Published: May 2020

The reagent RK [R=CH(SiMe3)2 or N(SiMe3)2] was expected to react with the low‐valent (DIPPBDI)Al (DIPPBDI=HC[C(Me)N(DIPP)]2, DIPP=2,6‐iPr‐phenyl) to give [(DIPPBDI)AlR]−K+. However, deprotonation of the Me group in the ligand backbone was observed and [H2C=C(N‐DIPP)−C(H)=C(Me)−N−DIPP]Al−K+ (1) crystallized as a bright‐yellow product (73 %). Like most anionic AlI complexes, 1 forms a dimer in which formally negatively charged Al centers are bridged by K+ ions, showing strong K+⋅⋅⋅DIPP interactions. The rather short Al–K bonds [3.499(1)–3.588(1) Å] indicate tight bonding of the dimer. According to DOSY NMR analysis, 1 is dimeric in C6H6 and monomeric in THF, but slowly reacts with both solvents. In reaction with C6H6, two C−H bond activations are observed and a product with a para‐phenylene moiety was exclusively isolated. DFT calculations confirm that the Al center in 1 is more reactive than that in (DIPPBDI)Al. Calculations show that both AlI and K+ work in concert and determines the reactivity of 1.
Oxidation, Coordination, and Nickel‐Mediated Deconstruction of a Highly Electron‐Rich Diboron Analogue of 1,3,5‐Hexatriene
Authors: Hermann Alexander , Fantuzzi Felipe , Arrowsmith Merle , Zorn Theresa , Krummenacher Ivo , Ritschel Benedikt , Radacki Krzysztof , Engels Bernd , Braunschweig Holger
Published: May 2020

The reductive coupling of an N‐heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2‐divinyldiborene, which, although isoelectronic to a 1,3,5‐triene, displays no extended π conjugation because of twisting of the C2B2C2 chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η2‐B2 and η4‐C2B2 fashion, respectively, it undergoes a complex rearrangement to an η4‐1,3‐diborete upon complexation with nickel(0).
Nickel‐Catalyzed Allylmethylation of Alkynes with Allylic Alcohols and AlMe3: Facile Access to Skipped Dienes and Trienes
Authors: Li Wanfang , Yu Shun , Li Jincan , Zhao Yu
Published: May 2020

We present herein an unprecedented allylative dicarbofunctionalization of alkynes with allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD)2, triphenylphosphine, and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all‐carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes.
Manganese‐Catalyzed anti‐Selective Asymmetric Hydrogenation of α‐Substituted β‐Ketoamides
Authors: Zhang Linli , Wang Zheng , Han Zhaobin , Ding Kuiling
Published: May 2020

A Mn‐catalyzed diastereo‐ and enantioselective hydrogenation of α‐substituted β‐ketoamides has been realized for the first time under dynamic kinetic resolution conditions. anti‐α‐Substituted β‐hydroxy amides, which are useful building blocks for the synthesis of bioactive molecules and chiral drugs, were prepared in high yields with excellent selectivity (up to >99 % dr and >99 % ee) and unprecedentedly high activity (TON up to 10000). The origin of the excellent stereoselectivity was clarified by DFT calculations.
Echinops bannaticus plant and Zinnia grandiflora extract as char biosource and reducing agent for the biosynthesis of Ag on magnetic char‐polymer: An efficient catalyst for water treatment
Authors: Sadjadi Samahe , Koohestani Fatemeh , Atai Mohammad
Published: May 2020

In attempt to expand the use of natural compounds for waste treatment, a novel catalyst with the utility for dye reductive degradation is reported. In the catalyst synthesis procedure, the plant Echinops bannaticus was applied as a biosource and hydrothermally treated to furnish a hydrochar that served as a support. The latter was magnetized, vinyl functionalized, and then polymerized with copolymer of 2‐hydroxyethyl methacrylate and methacrylate polyhedral oligomeric silsesquioxane. Subsequently, Ag nanoparticles were stabilized on the resultant composite with the aid of Zinnia grandiflora extract as a natural reducing agent. The resulting catalyst displayed high catalytic activity for the reduction of methylene orange and rhodamine B dyes in aqueous media at room temperature. The effects of the reaction variables, including the reaction time and temperature, and the catalyst loading, were examined and the kinetic and thermodynamic terms for both reactions were evaluated. Ea, ΔH#, and ΔS# values for the reduction of methyl orange were estimated as 50.0 kJ/mol, 51.50 kJ/mol, and −102.42 J mol−1 K−1, respectively. These values for rhodamine B were measured as 28.0 kJ/mol, 25.5 kJ/mol, and −187.56 J mol−1 K−1, respectively. The recyclability test also affirmed that the catalyst was recyclable for several runs with insignificant Ag leaching and decrement of its activity.
Cost‐effective and Efficient Catalyst of Bimetallic Nickel Iron Selenide toward Oxygen Evolution Reaction
Authors: Wei Pengkun , Hao Zewei , Kang Hongzhi , Yang  , Guo Donggang , Liu Lu
Published: May 2020

The incorporation of additional metal to form homo/heterojunction nanomaterials may enhance electrical conductivity and electrocatalytic performance. In this work, a novel Ni−Fe‐Se compound made through a facile solvothermal method with the presence of D‐(+)‐glucose (labeled as Ni0.5Fe0.5Se2/C) exhibited outstanding catalytic activity toward water oxidation. During oxygen evolution reaction (OER) process in alkaline condition, Ni0.5Fe0.5Se2/C catalyst shows an overpotential of 254 mV at 10 mA cm−2, 77 mV lower than that of the commercial RuO2, and an excellent stability.
Stereo‐ and Regioselective Cu‐Catalyzed Hydroboration of Alkynyl Chalcogenoethers
Authors: de Oliveira Isadora M. , Esteves Henrique A. , Darbem Mariana P. , Sartorelli Arthur , Correra Thiago C. , Rodrigues‐Oliveira André F. , Pimenta Daniel C. , Zukerman‐Schpector Julio , Manarin Flávia , Stefani Hélio A.
Published: May 2020

A mild stereo‐ and regioselective Cu‐catalyzed hydroboration method for the synthesis of (Z)‐seleno‐alkenyl boronates and (Z)‐thio‐alkenylboronates from internal alkynes in the presence of commercially available B2pin2 is presented. This highly selective transformation relies on the use of N‐heterocyclic carbene (NHC) complex IPrCuCl as the active catalytic species. We also explore the functionalization of the alkenylboronates obtained via oxidation to give α‐chalcogeno ketones, useful building blocks for the synthesis of more complex chalcogen‐containing molecules.
Biosynthetic Approaches towards the Design of Artificial Hydrogen‐Evolution Catalysts
Authors: Prasad Pallavi , Selvan Dhanashree , Chakraborty Saumen
Published: May 2020

Hydrogen is a clean and sustainable form of fuel that can minimize our heavy dependence on fossil fuels as the primary energy source. The need of finding greener ways to generate H2 gas has ignited interest in the research community to synthesize catalysts that can produce H2 by the reduction of H+. The natural H2 producing enzymes hydrogenases have served as an inspiration to produce catalytic metal centers akin to these native enzymes. In this article we describe recent advances in the design of a unique class of artificial hydrogen evolving catalysts that combine the features of the active site metal(s) surrounded by a polypeptide component. The examples of these biosynthetic catalysts discussed here include i) assemblies of synthetic cofactors with native proteins; ii) peptide‐appended synthetic complexes; iii) substitution of native cofactors with non‐native cofactors; iv) metal substitution from rubredoxin; and v) a reengineered Cu storage protein into a Ni binding protein. Aspects of key design considerations in the construction of these artificial biocatalysts and insights gained into their chemical reactivity are discussed.
Exploring Multi‐Subsite Binding Pockets in Proteins: DEEP‐STD NMR Fingerprinting and Molecular Dynamics Unveil a Cryptic Subsite at the GM1 Binding Pocket of Cholera Toxin B
Authors: Monaco Serena , Walpole Samuel , Doukani Hassan , Nepravishta Ridvan , Martínez‐Bailén Macarena , Carmona Ana T. , Ramos‐Soriano Javier , Bergström Maria , Robina Inmaculada , Angulo Jesus
Published: May 2020

Ligand‐based NMR techniques to study protein–ligand interactions are potent tools in drug design. Saturation transfer difference (STD) NMR spectroscopy stands out as one of the most versatile techniques, allowing screening of fragments libraries and providing structural information on binding modes. Recently, it has been shown that a multi‐frequency STD NMR approach, differential epitope mapping (DEEP)‐STD NMR, can provide additional information on the orientation of small ligands within the binding pocket. Here, the approach is extended to a so‐called DEEP‐STD NMR fingerprinting technique to explore the binding subsites of cholera toxin subunit B (CTB). To that aim, the synthesis of a set of new ligands is presented, which have been subject to a thorough study of their interactions with CTB by weak affinity chromatography (WAC) and NMR spectroscopy. Remarkably, the combination of DEEP‐STD NMR fingerprinting and Hamiltonian replica exchange molecular dynamics has proved to be an excellent approach to explore the geometry, flexibility, and ligand occupancy of multi‐subsite binding pockets. In the particular case of CTB, it allowed the existence of a hitherto unknown binding subsite adjacent to the GM1 binding pocket to be revealed, paving the way to the design of novel leads for inhibition of this relevant toxin.
Photoredox/Cobalt Dual‐Catalyzed Decarboxylative Elimination of Carboxylic Acids: Development and Mechanistic Insight
Authors: Cartwright Kaitie C. , Joseph Ebbin , Comadoll Chelsea G. , Tunge Jon A.
Published: May 2020

Recently, dual‐catalytic strategies towards the decarboxylative elimination of carboxylic acids have gained attention. Our lab previously reported a photoredox/cobaloxime dual catalytic method that allows the synthesis of enamides and enecarbamates directly from N‐acyl amino acids and avoids the use of any stoichiometric reagents. Further development, detailed herein, has improved upon this transformation's utility and further experimentation has provided new insights into the reaction mechanism. These new developments and insights are anticipated to aid in the expansion of photoredox/cobalt dual‐catalytic systems.
α‐Amidoaldehydes as Substrates in Rhodium‐Catalyzed Intermolecular Alkyne Hydroacylation: The Synthesis of α‐Amidoketones
Authors: Pal Ritashree , O'Brien Sean C. , Willis Michael C.
Published: May 2020

We show that readily available α‐amidoaldehydes are effective substrates for intermolecular Rh‐catalyzed alkyne hydroacylation reactions. The catalyst [Rh(dppe)(C6H5F)][BArF4] provides good reactivity, and allows a broad range of aldehydes and alkynes to be used as substrates, delivering α‐amidoketone products. High yields and high levels of regioselectivity are achieved. The use of α‐amidoaldehydes as substrates establishes that 1,4‐dicarbonyl motifs can be used as controlling groups in Rh‐catalyzed hydroacylation reactions.
Cu Nanoparticles Embedded in N‐Doped Carbon Materials for Oxygen Reduction Reaction
Authors: Wen Xudong , Qi Hui , Cheng Yan , Zhang Qiaoqiao , Hou Changmin , Guan Jingqi
Published: May 2020

Summary of main observation and conclusion

Development of eco‐friendly, cost‐effective, and high‐performance electrocatalysts to replace precious metal platinum for oxygen reduction reaction (ORR) has received increasing attention. Herein, we adopt a facile one‐pot strategy to embed Cu nanoparticles onto N‐doped carbon‐graphene (Cu@NC‐700). The Cu@NC‐700 exhibits robust and efficient ORR catalysis with positive half‐wave potential (~0.86 V vs. RHE) and low Tafel slope (33.9 mV∙dec–1) in 0.1 M KOH solution. Meanwhile, it manifests remarkable electrochemical stability, and strong tolerance to methanol crossover and carbon monoxide poisoning. The synergistic effect between Cu‐N‐C sites, Cu nanoparticles, and N‐doped carbon support speeds up ORR electrocatalysis.
Distribution and localization of phosphatidylinositol 5‐phosphate, 4‐kinase alpha and beta in the brain
Authors: Noch Evan K. , Yim Isaiah , Milner Teresa A. , Cantley Lewis C.
Published: May 2020

Phosphatidylinositol‐4,5‐bisphosphate (PI‐4,5‐P2) is critical for synaptic vesicle docking and fusion and generation of the second messengers, diacylglycerol and inositol‐1,4,5‐trisphosphate. PI‐4,5‐P2 can be generated by two families of kinases: type 1 phosphatidylinositol‐4‐phosphate 5‐kinases, encoded by PIP5K1A, PIP5K1B and PIP5K1C, and type 2 phosphatidylinositol‐5‐phosphate 4‐kinases, encoded by PIP4K2A, PIP4K2B, and PIP4K2C. While the roles of the type 1 enzymes in brain function have been extensively studied, the roles of the type 2 enzymes are poorly understood. Using selective antibodies validated by genetic deletion of pip4k2a or pip4k2b in mouse brain, we characterized the location of the enzymes, PI5P4Kα and PI5P4Kβ, encoded by these genes. In mice, we demonstrate that PI5P4Kα is expressed in adulthood, whereas PI5P4Kβ is expressed early in development. PI5P4Kα localizes to white matter tracts, especially the corpus callosum, and at a low level in neurons, while PI5P4Kβ is expressed in neuronal populations, especially hippocampus and cortex. Dual labeling studies demonstrate that PI5P4Kα co‐localizes with the oligodendrocyte marker, Olig2, whereas PI5P4Kβ co‐localizes with the neuronal marker, NeuN. Ultrastructural analysis demonstrates that both kinases are contained in axon terminals and dendritic spines adjacent to the synaptic membrane, which support a potential role in synaptic transmission. Immunoperoxidase analysis of macaque and human brain tissue demonstrate a conserved pattern for PI5P4Kα and PI5P4Kβ. These results highlight the diverse cell‐autonomous expression of PI5P4Kα and PI5P4Kβ and support further exploration into their role in synaptic function in the brain.
Dynamics of the fragile X mental retardation protein correlates with cellular and synaptic properties in primary auditory neurons following afferent deprivation
Authors: Yu Xiaoyan , Wang Xiaoyu , Sakano Hitomi , Zorio Diego A. R. , Wang Yuan
Published: May 2020

Afferent activity dynamically regulates neuronal properties and connectivity in the central nervous system. The Fragile X mental retardation protein (FMRP) is an RNA‐binding protein that regulates cellular and synaptic properties in an activity‐dependent manner. Whether and how FMRP level and localization are regulated by afferent input remains sparsely examined and how such regulation is associated with neuronal response to changes in sensory input is unknown. We characterized changes in FMRP level and localization in the chicken nucleus magnocellularis (NM), a primary cochlear nucleus, following afferent deprivation by unilateral cochlea removal. We observed rapid (within 2 hr) aggregation of FMRP immunoreactivity into large granular structures in a subset of deafferented NM neurons. Neurons that exhibited persistent FMRP aggregation at 12–24 hr eventually lost cytoplasmic Nissl substance, indicating cell death. A week later, FMRP expression in surviving neurons regained its homeostasis, with a slightly reduced immunostaining intensity and enhanced heterogeneity. Correlation analyses under the homeostatic status (7–14 days) revealed that neurons expressing relatively more FMRP had a higher capability of maintaining cell body size and ribosomal activity, as well as a better ability to detach inactive presynaptic terminals. Additionally, the intensity of an inhibitory postsynaptic protein, gephyrin, was reduced following deafferentation and was positively correlated with FMRP intensity, implicating an involvement of FMRP in synaptic dynamics in response to reduced afferent inputs. Collectively, this study demonstrates that afferent input regulates FMRP expression and localization in ways associated with multiple types of neuronal responses and synaptic rearrangements.
Separation and Detection of meta‐ and ortho‐Substituted Benzene Isomers by Using a Water‐Soluble Pillar[5]arene
Authors: Zhang Gengwu , Moosa Basem , Chen Aiping , Khashab Niveen M.
Published: May 2020

Efficient and energy‐saving separation of benzene isomers bearing a diverse range of functional groups is a great challenge due to their overlapping physicochemical properties. Here, we report the successfully use of a water‐soluble pillar[5]arene (WP5) as a multifunctional material for the separation and detection of meta/ortho‐substituted benzene isomers in water. A liquid‐liquid extraction strategy was used for the separation of these benzene isomers based on their different affinity for WP5 in water. The selectivities for the meta over the ortho isomer for xylenes, chlorotoluene, and bromotoluene was 88.6 %, 88.3 %, and 95.0 % respectively, in one extraction cycle. Furthermore, a fluorescence indicator system based on WP5 and a fluorescent dye molecule (10‐methylacridinium, D) was adopted and exhibited significant fluorescence and optical discrimination upon the addition of meta‐ compared to ortho‐xylene, which implies that a simple “turn‐on” detection can be performed prior to engaging in the separation process.
Nozzle‐Assisted Simultaneous Precipitation Method for Energetic FOX‐7/RDX Composite Microspheres with Improved Thermal Stability and Sensitivity
Authors: Xu Ruixuan , An Chongwei , Ye Baoyun , Liu Qian , Wang Jiechao , Wang Jingyu
Published: May 2020

Energetic 1,1‐diamino‐2,2‐dinitroethylene/hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (FOX‐7/RDX) composite crystals are fabricated via a newly introduced method named nozzle‐assisted simultaneous precipitation. Dimethyl sulfoxide is used as the solvent and FOX‐7/RDX composite crystals are prepared at different molar ratios of FOX‐7 and RDX. Regularly spherical FOX‐7/RDX particles are obtained under the 1:1 molar ratio of FOX‐7 and RDX and confirmed by field emission scanning electron microscopy. The result characterized by a laser particle size analyzer shows that the FOX‐7/RDX composite particles have a narrow particle size distribution with a median diameter of ≈1.57 µm. The structure of FOX‐7/RDX particles is confirmed using powder X‐ray diffraction and Fourier transform infrared spectroscopy, and the patterns suggest differences compared with FOX‐7/RDX mixture by mechanical mixing. Differential scanning calorimetry and thermal gravimetric test show an advanced decomposition peak temperature compared with raw FOX‐7 and RDX, and the apparent activation energy (Ea) of FOX‐7/RDX composite particles increases by 72.44 kJ mol−1 than that of raw RDX. Furthermore, the characteristic drop height of FOX‐7/RDX composite particles increases to 61.9 cm, which is a 111.3% increasement compared to raw RDX, indicating an obviously significant improvement concerning mechanical safety.
Photocatalytic Activity, Negative AC‐Electrical Conductivity, Dielectric Modulus, and Impedance Properties in 0.6 (Al0.2La0.8TiO3) + 0.4 (BiFeO3) Nanocomposite
Authors: Mallikarjuna A. , Ramesh Singampalli , Kumar Nagasamudram Suresh , Naidu Kadiyala Chandra Babu , Ratnam K. Venkata , Manjunatha H.
Published: May 2020

A series of nanocomposites with a chemical formula of (1−x) (Al0.2La0.8TiO3) + x (BiFeO3)/ALTBF is prepared through low temperature hydrothermal method. The tetragonal phases are detected at x = 0.2 and the x = 0.4–0.8 composites show the existence of cubic phases. The transmission electron microscope pictures show the presence of well‐defined spherical particles for all composites. Furthermore, photocatalytic activity is observed for x = 0.2–0.8 composites during time intervals ranging from 0 to 240 min. The x = 0.2, 0.6, and 0.8 nanocomposites reveal the usual behavior of ac‐electrical conductivity (σac), dielectric modulus parameters (M′ and M″), and impedance parameters (Z′ and Z″). However, interestingly, x = 0.4 composite performs the negative values of electrical parameters like σac, M′, M″, and Z″. This implies that x = 0.4 composite behaves like a metamaterial possessing negative indexed electrical parameters. Therefore, x = 0.4 composite can be well suited for microwave device applications at high frequency.