bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effective Manipulation of Spin Dynamics by Polarization Electric Field in InGaN/GaN Quantum Wells at Room Temperature
Authors: Liu Xingchen , Tang Ning , Zhang Shixiong , Zhang Xiaoyue , Guan Hongming , Zhang Yunfan , Qian Xuan , Ji Yang , Ge Weikun , Shen Bo 
Published: June 2020

AbstractIII‐nitride wide bandgap semiconductors are favorable materials for developing room temperature spintronic devices. The effective manipulation of spin dynamics is a critical request to realize spin field‐effect transistor (FET). In this work, the dependence of the spin relaxation time on external strain‐induced polarization electric field is investigated in InGaN/GaN multiple quantum wells (MQWs) by time‐resolved Kerr rotation spectroscopy. Owing to the almost canceled two different spin–orbit coupling (SOC), the spin relaxation time as long as 311 ps in the MQWs is obtained at room temperature, being much longer than that in bulk GaN. Furthermore, upon applying an external uniaxial strain, the spin relaxation time decreases sensitively, which originates from the breaking of the SU(2) symmetry. The extracted ratio of the SOC coefficients shows a linear dependence on the external strain, confirming the essential role of the polarization electric field. This effective manipulation of the spin relaxation time sheds light on GaN‐based nonballistic spin FET working at room temperature.
Ion Migration‐Induced Amorphization and Phase Segregation as a Degradation Mechanism in Planar Perovskite Solar Cells
Authors: Di Girolamo Diego , Phung Nga , Kosasih Felix Utama , Di Giacomo Francesco , Matteocci Fabio , Smith Joel A. , Flatken Marion A. , Köbler Hans , Turren Cruz Silver H. , Mattoni Alessandro , Cinà Lucio , Rech Bernd , Latini Alessandro , Divitini Giorgio , Ducati Caterina , Di Carlo Aldo , Dini Danilo , Abate Antonio 
Published: June 2020

AbstractThe operation of halide perovskite optoelectronic devices, including solar cells and LEDs, is strongly influenced by the mobility of ions comprising the crystal structure. This peculiarity is particularly true when considering the long‐term stability of devices. A detailed understanding of the ion migration‐driven degradation pathways is critical to design effective stabilization strategies. Nonetheless, despite substantial research in this first decade of perovskite photovoltaics, the long‐term effects of ion migration remain elusive due to the complex chemistry of lead halide perovskites. By linking materials chemistry to device optoelectronics, this study highlights that electrical bias‐induced perovskite amorphization and phase segregation is a crucial degradation mechanism in planar mixed halide perovskite solar cells. Depending on the biasing potential and the injected charge, halide segregation occurs, forming crystalline iodide‐rich domains, which govern light emission and participate in light absorption and photocurrent generation. Additionally, the loss of crystallinity limits charge collection efficiency and eventually degrades the device performance.
Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor
Authors: Che Weilong , Xie Yujun , Li Zhen 
Published: June 2020

AbstractOwing to the faster response time, wider viewing angle and thinner thickness of organic light emitting diodes (OLEDs) than the conventional displays, the development of high‐efficiency light‐emitting materials has become the focus of attention. In recent years, the TADF materials have aroused widespread attention and experienced rapid development as an emitter in OLEDs, since the maximum internal quantum efficiency can reach 100% theoretically. TADF materials have exhibited the potential to be a low‐cost alternative to expensive phosphorescent luminophors. Whereas, the high resolution displays must endow the characteristics of stable and efficient panchromatic emission. The chemical structure of TADF materials are generally composed of electrical donor and acceptor, the emission colors and efficiency can be adjusted by the charge transfer between them. In this paper, TADF emitters with different emission colors are reviewed, accompanied with the investigation on their molecular design strategies and photophysical properties. In addition, the development direction and application of TADF materials are prospected.
Nature of the Arsonium‐Ylide Ph3As=CH2 and a Uranium(IV) Arsonium–Carbene Complex
Authors: Seed John A. , Sharpe Helen R. , Futcher Harry J. , Wooles Ashley J. , Liddle Stephen T. 
Published: June 2020

AbstractTreatment of [Ph3EMe][I] with [Na{N(SiMe3)2}] affords the ylides [Ph3E=CH2] (E=As, 1As; P, 1P). For 1As this overcomes prior difficulties in the synthesis of this classical arsonium‐ylide that have historically impeded its wider study. The structure of 1As has now been determined, 45 years after it was first convincingly isolated, and compared to 1P, confirming the long‐proposed hypothesis of increasing pyramidalisation of the ylide‐carbon, highlighting the increasing dominance of E+−C− dipolar resonance form (sp3‐C) over the E=C ene π‐bonded form (sp2‐C), as group 15 is descended. The uranium(IV)–cyclometallate complex [U{N(CH2CH2NSiPri3)2(CH2CH2SiPri2CH(Me)CH2)}] reacts with 1As and 1P by α‐proton abstraction to give [U(TrenTIPS)(CHEPh3)] (TrenTIPS=N(CH2CH2NSiPri3)3; E=As, 2As; P, 2P), where 2As is an unprecedented structurally characterised arsonium‐carbene complex. The short U−C distances and obtuse U‐C‐E angles suggest significant U=C double bond character. A shorter U−C distance is found for 2As than 2P, consistent with increased uranium‐ and reduced pnictonium‐stabilisation of the carbene as group 15 is descended, which is supported by quantum chemical calculations.
Multifunctional Active‐Center‐Transferable Platinum/Lithium Cobalt Oxide Heterostructured Electrocatalysts towards Superior Water Splitting
Authors: Zheng Xiaobo , Cui Peixin , Qian Yumin , Zhao Guoqiang , Zheng Xusheng , Xu Xun , Cheng Zhenxiang , Liu Yuanyue , Dou Shi Xue , Sun Wenping 
Published: June 2020

AbstractDesigning cost‐effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active‐center‐transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO2) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO2 nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Specifically, Pt species are the active centers and LiCoO2 acts as the co‐catalyst for HER, whereas the active center transfers to LiCoO2 and Pt turns into the co‐catalyst for OER. The unique architecture of Pt/LiCoO2 heterostructure provides abundant interfaces with favorable electronic structure and coordination environment towards optimal adsorption behavior of reaction intermediates. The 30 % Pt/LiCoO2 heterostructured electrocatalyst delivers low overpotentials of 61 and 285 mV to achieve 10 mA cm−2 for HER and OER in alkaline medium, respectively.
Reconciling Electrostatic and n→π* Orbital Contributions in Carbonyl Interactions
Authors: Muchowska Kamila B. , Pascoe Dominic J. , Borsley Stefan , Smolyar Ivan V. , Mati Ioulia K. , Adam Catherine , Nichol Gary S. , Ling Kenneth B. , Cockroft Scott L. 
Published: June 2020

AbstractInteractions between carbonyl groups are prevalent in protein structures. Earlier investigations identified dominant electrostatic dipolar interactions, while others implicated lone pair n→π* orbital delocalisation. Here these observations are reconciled. A combined experimental and computational approach confirmed the dominance of electrostatic interactions in a new series of synthetic molecular balances, while also highlighting the distance‐dependent observation of inductive polarisation manifested by n→π* orbital delocalisation. Computational fiSAPT energy decomposition and natural bonding orbital analyses correlated with experimental data to reveal the contexts in which short‐range inductive polarisation augment electrostatic dipolar interactions. Thus, we provide a framework for reconciling the context dependency of the dominance of electrostatic interactions and the occurrence of n→π* orbital delocalisation in C=O⋅⋅⋅C=O interactions.
Near‐Infrared‐III‐Absorbing and ‐Emitting Dyes: Energy‐Gap Engineering of Expanded Porphyrinoids via Metallation
Authors: Wang Yue , Ogasahara Koki , Tomihama Daisuke , Mysliborski Radomir , Ishida Masatoshi , Hong Yongseok , Notsuka Yusuke , Yamaoka Yoshihisa , Murayama Tomotaka , Muranaka Atsuya , Uchiyama Masanobu , Mori Shigeki , Yasutake Yuhsuke , Fukatsu Susumu , Kim Dongho , Furuta Hiroyuki 
Published: June 2020

AbstractThe synthesis of organometallic complexes of modified 26π‐conjugated hexaphyrins with absorption and emission capabilities in the third near‐infrared region (NIR‐III) is described. Symmetry alteration of the frontier molecular orbitals (MOs) of bis‐PdII and bis‐PtII complexes of hexaphyrin via N‐confusion modification led to substantial metal dπ–pπ interactions. This MO mixing, in turn, resulted in a significantly narrower HOMO–LUMO energy gap. A remarkable long‐wavelength shift of the lowest S0→S1 absorption beyond 1700 nm was achieved with the bis‐PtII complex, t‐Pt2‐3. The emergence of photoacoustic (PA) signals maximized at 1700 nm makes t‐Pt2‐3 potentially useful as a NIR‐III PA contrast agent. The rigid bis‐PdII complexes, t‐Pd2‐3 and c‐Pd2‐3, are rare examples of NIR emitters beyond 1500 nm. The current study provides new insight into the design of stable, expanded porphyrinic dyes possessing NIR‐III‐emissive and photoacoustic‐response capabilities.
Cross‐Linked Polyphosphazene Hollow Nanosphere‐Derived N/P‐Doped Porous Carbon with Single Nonprecious Metal Atoms for the Oxygen Reduction Reaction
Authors: Wei Xuan , Zheng Diao , Zhao Ming , Chen Hongzhong , Fan Xun , Gao Bin , Gu Long , Guo Yi , Qin Jianbin , Wei Jing , Zhao Yanli , Zhang Guangcheng 
Published: June 2020

AbstractHeteroatom‐doped polymers or carbon nanospheres have attracted broad research interest. However, rational synthesis of these nanospheres with controllable properties is still a great challenge. Herein, we develop a template‐free approach to construct cross‐linked polyphosphazene nanospheres with tunable hollow structures. As comonomers, hexachlorocyclotriphosphazene provides N and P atoms, tannic acid can coordinate with metal ions, and the replaceable third comonomer can endow the materials with various properties. After carbonization, N/P‐doped mesoporous carbon nanospheres were obtained with small particle size (≈50 nm) and high surface area (411.60 m2 g−1). Structural characterization confirmed uniform dispersion of the single atom transition metal sites (i.e., Co‐N2P2) with N and P dual coordination. Electrochemical measurements and theoretical simulations revealed the oxygen reduction reaction performance. This work provides a solution for fabricating diverse heteroatom‐containing polymer nanospheres and their derived single metal atom doped carbon catalysts.
Building up Strain in One Step: Synthesis of an Edge‐Fused Double Silacyclobutene from an Extensively Trichlorosilylated Butadiene Dianion
Authors: Georg Isabelle , Bursch Markus , Stückrath Julius B. , Alig Edith , Bolte Michael , Lerner Hans‐Wolfram , Grimme Stefan , Wagner Matthias 
Published: June 2020

AbstractThe exhaustive trichlorosilylation of hexachloro‐1,3‐butadiene was achieved in one step by using a mixture of Si2Cl6 and [nBu4N]Cl (7:2 equiv) as the silylation reagent. The corresponding butadiene dianion salt [nBu4N]2[1] was isolated in 36 % yield after recrystallization. The negative charges of [1]2− are mainly delocalized across its two carbanionic (Cl3Si)2C termini (α‐effect of silicon) such that the central bond possesses largely C=C double‐bond character. Upon treatment with 4 equiv of HCl, [1]2− is converted into neutral 1,2,3,4‐tetrakis(trichlorosilyl)but‐2‐ene, 3. The Cl− acceptor AlCl3, induces a twofold ring‐closure reaction of [1]2− to form a six‐membered bicycle 4 in which two silacyclobutene rings are fused along a shared C=C double bond (84 %). Compound 4, which was structurally characterized by X‐ray crystallography, undergoes partial ring opening to a monocyclic silacyclobutene 2 in the presence of HCl, but is thermally stable up to at least 180 °C.
Three‐Dimensional Cuprous Lead Bromide Framework with Highly Efficient and Stable Blue Photoluminescence Emission
Authors: Sun Chen , Guo Ya‐Hui , Han Sha‐Sha , Li Jing‐Zhao , Jiang Kuan , Dong Lin‐Feng , Liu Qi‐Long , Yue Cheng‐Yang , Lei Xiao‐Wu 
Published: June 2020

AbstractConsidering the instability and low photoluminescence quantum yield (PLQY) of blue‐emitting perovskites, it is still challenging and attractive to construct single crystalline hybrid lead halides with highly stable and efficient blue light emission. Herein, by rationally introducing d10 transition metal into single lead halide as new structural building unit and optical emitting center, we prepared a bimetallic halide of [(NH4)2]CuPbBr5 with new type of three‐dimensional (3D) anionic framework. [(NH4)2]CuPbBr5 exhibits strong band‐edge blue emission (441 nm) with a high PLQY of 32 % upon excitation with UV light. Detailed photophysical studies indicate [(NH4)2]CuPbBr5 also displays broadband red light emissions derived from self‐trapped states. Furthermore, the 3D framework features high structural and optical stabilities at extreme environments during at least three years. To our best knowledge, this work represents the first 3D non‐perovskite bimetallic halide with highly efficient and stable blue light emission.
Profiling and Identification of Biocatalyzed Transformation of Sulfoxaflor In Vivo
Authors: Xu Liwei , Guo Lingling , Wang Zhongxing , Xu Xinxin , Zhang Shuang , Wu Xiaoling , Kuang Hua , Xu Chuanlai 
Published: June 2020

AbstractIn the present study, we investigated the biotransformation of the neonicotinoid pesticide sulfoxaflor and the metabolic responses in Sprague‐Dawley rats. Sulfoxaflor transformation was catalyzed by cytochrome P450 while five phase I and four phase II metabolites were identified for the first time in vivo. The experimental results demonstrated that sulfoxaflor brought about the metabolic profiling disturbances in liver and bile. Exposure to sulfoxaflor caused dysregulation of bile acid synthesis and reabsorption by the expression of farnesoid X receptor (FXR). Our data provided insights into biotransformation of chemicals while enabling the implementation of a new toolbox for the design of sulfoximine compounds.
Quantitative Assessment of Tip Effects in Single‐Molecule High‐Speed Atomic Force Microscopy Using DNA Origami Substrates
Authors: Kielar Charlotte , Zhu Siqi , Grundmeier Guido , Keller Adrian 
Published: June 2020

AbstractHigh‐speed atomic force microscopy (HS‐AFM) is widely employed in the investigation of dynamic biomolecular processes at a single‐molecule level. However, it remains an open and somewhat controversial question, how these processes are affected by the rapidly scanned AFM tip. While tip effects are commonly believed to be of minor importance in strongly binding systems, weaker interactions may significantly be disturbed. Herein, we quantitatively assess the role of tip effects in a strongly binding system using a DNA origami‐based single‐molecule assay. Despite its femtomolar dissociation constant, we find that HS‐AFM imaging can disrupt monodentate binding of streptavidin (SAv) to biotin (Bt) even under gentle scanning conditions. To a lesser extent, this is also observed for the much stronger bidentate SAv–Bt complex. The presented DNA origami‐based assay can be universally employed to quantify tip effects in strongly and weakly binding systems and to optimize the experimental settings for their reliable HS‐AFM imaging.
Stereodivergent Alkyne Hydrofluorination Using Protic Tetrafluoroborates as Tunable Reagents
Authors: Guo Rui , Qi Xiaotian , Xiang Hengye , Geaneotes Paul , Wang Ruihan , Liu Peng , Wang Yi‐Ming 
Published: June 2020

AbstractThe discovery of safe, general, and practical procedures to prepare vinyl fluorides from readily available precursors remains a synthetic challenge. The metal‐free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Introduced here is an inexpensive and easily handled reagent that enables the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These reaction conditions were suitable for a diverse collection of alkynes, including several highly functionalized pharmaceutical derivatives. Computational and experimental mechanistic studies support C−F bond formation through vinyl cation intermediates, with the E‐ and Z‐hydrofluorination products forming under kinetic and thermodynamic control, respectively.
Twisted Surfaces in Porous Single Crystals to Deliver Enhanced Catalytic Activity and Stability
Authors: Lin Guoming , Li Hao , Xie Kui 
Published: June 2020

AbstractPorous single crystals which combine ordered lattice structures and disordered inter‐connected pores would provide an alternative to create twisted surface in porous microstructures. Now, transition‐metal nitride Nb4N5 and MoN single crystals are grown on a 2 cm scale to create well‐defined active structures at twisted surfaces. High catalytic activity and stability toward non‐oxidative dehydrogenation of ethane to ethylene is observed. Unsaturated metal–nitrogen coordination structures including Nb‐N1/5, Nb‐N2/5, Mo‐N1/3, and Mo‐N1/6 at the twisted surface mainly account for the C−H activation with chemisorption of H in molecular ethane at the twisted surface, which not only improves dehydrogenation performance but also avoids the deep cracking of ethane to enhance coking resistance. 11–25 % ethane conversion and 98–99 % ethylene selectivity is demonstrated without degradation being observed even after the operation of 50 hours.
Octacyanidorhenate(V) Ion as an Efficient Linker for Hysteretic Two‐Step Iron(II) Spin Crossover Switchable by Temperature, Light, and Pressure
Authors: Chorazy Szymon , Charytanowicz Tomasz , Pinkowicz Dawid , Wang Junhao , Nakabayashi Koji , Klimke Stephen , Renz Franz , Ohkoshi Shin‐ichi , Sieklucka Barbara 
Published: June 2020

AbstractA two‐step hysteretic FeII spin crossover (SCO) effect was achieved in programmed layered Cs{[Fe(3‐CNpy)2][Re(CN)8]}⋅H2O (1) (3‐CNpy=3‐cyanopyridine) assembly consisting of cyanido‐bridged FeII‐ReV square grid sheets bonded by Cs+ ions. The presence of two non‐equivalent FeII sites and the conjunction of 2D bimetallic coordination network with non‐covalent interlayer interactions involving Cs+, [ReV(CN)8]3− ions, and 3‐CNpy ligands, leads to the occurrence of two steps of thermal SCO with strong cooperativity giving a double thermal hysteresis loop. The resulting spin‐transition phenomenon could be tuned by an external pressure giving the room‐temperature range of SCO, as well as by visible‐light irradiation, inducing an efficient recovery of the high‐spin FeII state at low temperatures. We prove that octacyanidorhenate(V) ion is an outstanding metalloligand for induction of a cooperative multistep, multiswitchable FeII SCO effect.
Direct synthesis of completely unsymmetrical triarylmethanes via Fe(III) salt‐mediated in situ o‐quinone methides process
Authors: Yang Qi , Wu Run‐Shi , Wu Ke‐Xin , Gu Ying‐Chun , Yu Ya‐Qin , Xu Da‐Zhen 
Published: June 2020

AbstractAn efficient and straightforward synthetic approach to completely unsymmetrical triarylmethanes through the situ‐generated o‐quinone methides from readily available starting materials has been successfully developed. In the presence of an Fe(III) salt, three different aromatic rings, including salicylaldehydes, arylboronic acids, and arenes, were incorporated into one molecule in a single step under the base/ligand‐free conditions. The related reactions show high chemoselectivity and afford a variety of completely unsymmetrical triarylmethane products in good to excellent yields.
A parametric simulation on the effect of the rejected brine temperature on the performance of multieffect distillation with thermal vapour compression desalination process and its environmental impacts
Authors: Buabbas Saleh K. , Al‐Obaidi Mudhar A. , Mujtaba Iqbal M. 
Published: June 2020

AbstractMultieffect distillation with thermal vapour compression (MED–TVC) is one of the most attractive thermal desalination technologies for the production of freshwater. Several mathematical models were presented in the open literature to analyse the steady‐state performance of such process. However, these models have several limitations and assumptions. Therefore, there remains the challenge of having a reliable model to accurately predict the performance of the MED process. Thus, this research attempts to resolve this challenge by rectifying the shortcomings of the models found in the literature and create a new one. The robustness of the developed model is evaluated against the actual data of Umm Al‐Nar commercial plant situated in UAE. In seawater desalinisation, a large amount of high‐salinity stream (brine) is rejected back into the sea. This paper investigates the influence of the rejected (exit) brine temperature on the system performance parameters of MED–TVC process. Specifically, these parameters are considered as total heat consumption, gain output ratio, freshwater production, heat transfer area and performance ratio. Also, the particular parameters of TVC section of the entrainment ratio, compression ratio and expansion ratio are also addressed. Moreover, a critical evaluation of the influence of the rejected brine temperature on the seawater is also embedded.
Bone histology and microanatomy of Edaphosaurus and Dimetrodon (Amniota, Synapsida) vertebrae from the Lower Permian of Texas
Authors: Agliano Amin , Sander P. Martin , Wintrich Tanja 
Published: June 2020

AbstractHere we describe the histology and microanatomy of vertebral centra of the iconic pelycosaur‐grade synapsids Edaphosaurus boanerges and Dimetrodon spp. Vertebrae from different axial positions and, in the case of Dimetrodon, from different ontogenetic stages were selected. For the histological description, we produced histological petrographic thin sections ground to a thickness of 50–80 μm of the vertebrae in the sagittal and transversal cutting planes. After the preparation process, the thin sections were examined under transmitted and cross‐polarized light in a polarized microscope. The analyzed vertebrae reveal similar bone tissues, where both taxa have cortical parallel‐fibered bone (PFB). PFB and lamellar bone (LB) forms in the cancellous part. However, in juvenile Dimetrodon, woven‐fibered bone (WFB) is also deposited and shows a high degree of vascularity. This suggests that Dimetrodon had slightly faster bone growth than Edaphosaurus, which is mainly made of PFB and LB and shows poorly developed vascular canals. In addition, one specimen of Dimetrodon displays the preservation of an ossified notochord, which can be assumed to be indicative of how the intervertebral tissues were developed. Historically, evidence of how the joint between Dimetrodon vertebral centra was built was lacking until this specimen appeared. If the notochord ran persistently through the vertebrae, it would have possibly increased the stiffness of the vertebral column and would have affected the limbs and locomotion. Furthermore, the organization of trabeculae and relative thickness of the vertebral cortex gives insights into how the animals were adapted to their habitat.