bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Writing of Elastic Fibers with Optical, Electrical, and Microfluidic Functionality
Authors: Athanasiadis Markos , Pak Anna , Afanasenkau Dzmitry , Minev Ivan R. 
Published: March 2019

AbstractDirect Ink Writing is an additive fabrication technology that allows the integration of a diverse range of functional materials into soft and bioinspired devices such as robots and human‐machine interfaces. Typically, a viscoelastic ink is extruded from a nozzle as a continuous filament of circular cross section. Here it is shown that a careful selection of printing parameters such as nozzle height and speed can produce filaments with a range of cross‐sectional geometries. Thus, elliptic cylinder‐, ribbon‐, or groove‐shaped filaments can be printed. By using the nozzle as a stylus for postprint filament modification, even filaments with an embedded microfluidic channel can be produced. This strategy is applied to directly write freeform and elastic optical fibers, electrical interconnects, and microfluidics. The integration of these components into simple sensor‐actuator systems is demonstrated. Prototypes of an optical fiber with steerable tip and a thermal actuation system for soft tissues are presented.
Emerging Artificial Synaptic Devices for Neuromorphic Computing
Authors: Wan Qingzhou , Sharbati Mohammad T. , Erickson John R. , Du Yanhao , Xiong Feng 
Published: March 2019

AbstractIn today's era of big‐data, a new computing paradigm beyond today's von‐Neumann architecture is needed to process these large‐scale datasets efficiently. Inspired by the brain, which is better at complex tasks than even supercomputers with much better efficiency, the field of neuromorphic computing has recently attracted immense research interest and can have a profound impact in next‐generation computing. Unlike modern computers that use digital “0” and “1” for computation, biological neural networks exhibit analog changes in synaptic connections during the decision‐making and learning processes. Currently, the neuron node is usually implemented by dozens of silicon transistors, an approach that is energy‐intensive and nonscalable. In this paper, recent developments of synaptic electronics for the hardware implementation and acceleration of artificial neural networks will be discussed. Learning mechanisms and synaptic plasticity in the brain and the device level requirements for synaptic electronics will briefly be reviewed, emphasizing the nuance compared to requirements for nonvolatile memories. Several categories of emerging synaptic devices based on phase change memory, resistive memory, electrochemical devices, and 2D devices will be introduced, as well as their associated advantages, disadvantages, and future prospects.
High‐Performance Transparent and Flexible Triboelectric Nanogenerators Based on PDMS‐PTFE Composite Films
Authors: Li Gui‐Zhong , Wang Gui‐Gen , Ye Da‐Ming , Zhang Xu‐Wu , Lin Zhao‐Qing , Zhou Hai‐Ling , Li Fei , Wang Bao‐Lin , Han Jie‐Cai 
Published: March 2019

AbstractPoly(dimethylsiloxane) (PDMS) is commonly used as the negative friction layer of triboelectric nanogenerator (TENG) which can harvest ubiquitous mechanical energy. However, it is essential to improve the energy output of PDMS‐based TENGs with high visible transmittance for transparent flexible TENG. In this study, a simple, cost‐effective and efficient approach is demonstrated to modify PDMS without degrading high transparency. The novel flexible TENG based on PDMS‐PTFE composite film exhibits high output voltage and large transfer charge quantity of 95 V and 85 nC respectively, which are enhanced more than threefold in the output compared with pristine PDMS‐based TENG. And the TENG device generates average power output of 3.0 W m−2 across the matched optimal load resistance. The enhancement is attributed to PTFE particles dispersed in PDMS matrix, which can increase surface potential and reduce work function. Moreover, the TENG device also remains good transparency and flexibility, which satisfies the demands of transparent and flexible electronic devices. The proposed PDMS/PTFE based TENG shows good application prospects for various power sensors and even wearable energy suppliers.
Efficient Defect Passivation for Perovskite Solar Cells by Controlling the Electron Density Distribution of Donor‐π‐Acceptor Molecules
Authors: Wu Tianhao , Wang Yanbo , Li Xing , Wu Yongzhen , Meng Xiangyue , Cui Danyu , Yang Xudong , Han Liyuan 
Published: March 2019

AbstractOrganic–inorganic hybrid perovskite solar cells (PSCs) are a promising photovoltaic technology that has rapidly developed in recent years. Nevertheless, a large number of ionic defects within perovskite absorber can serve as non‐radiative recombination center to limit the performance of PSCs. Here, organic donor‐π‐acceptor (D‐π‐A) molecules with different electron density distributions are employed to efficiently passivate the defects in the perovskite films. The X‐ray photoelectron spectroscopy (XPS) analysis shows that the strong electron donating N,N‐dibutylaminophenyl unit in a molecule causes an increase in the electron density of the passivation site that is a carboxylate group, resulting in better binding with the defects of under‐coordinated Pb2+ cations. Carrier lifetime in the perovskite films measured by the time‐resolved photoluminescence spectrum is also prolonged by an increase in donation ability of the D‐π‐A molecules. As a consequence, these benefits contribute to an increase of 80 mV in the open circuit voltage of the devices, enabling a maximum power conversion efficiency (PCE) of 20.43%, in comparison with PCE of 18.52% for the control device. The authors' findings provide a novel strategy for efficient defect passivation in the perovskite solar cells based on controlling the electronic configuration of passivation molecules.
Sub‐6 nm Fully Ordered L10‐Pt–Ni–Co Nanoparticles Enhance Oxygen Reduction via Co Doping Induced Ferromagnetism Enhancement and Optimized Surface Strain
Authors: Wang Tanyuan , Liang Jiashun , Zhao Zhonglong , Li Shenzhou , Lu Gang , Xia Zhengcai , Wang Chao , Luo Jiahuan , Han Jiantao , Ma Cheng , Huang Yunhui , Li Qing 
Published: March 2019

AbstractEngineering the crystal structure of Pt–M (M = transition metal) nanoalloys to chemically ordered ones has drawn increasing attention in oxygen reduction reaction (ORR) electrocatalysis due to their high resistance against M etching in acid. Although Pt–Ni alloy nanoparticles (NPs) have demonstrated respectable initial ORR activity in acid, their stability remains a big challenge due to the fast etching of Ni. In this work, sub‐6 nm monodisperse chemically ordered L10‐Pt–Ni–Co NPs are synthesized for the first time by employing a bifunctional core/shell Pt/NiCoOx precursor, which could provide abundant O‐vacancies for facilitated Pt/Ni/Co atom diffusion and prevent NP sintering during thermal annealing. Further, Co doping is found to remarkably enhance the ferromagnetism (room temperature coercivity reaching 2.1 kOe) and the consequent chemical ordering of L10‐Pt–Ni NPs. As a result, the best‐performing carbon supported L10‐PtNi0.8Co0.2 catalyst reveals a half‐wave potential (E1/2) of 0.951 V versus reversible hydrogen electrode in 0.1 m HClO4 with 23‐times enhancement in mass activity over the commercial Pt/C catalyst along with much improved stability. Density functional theory (DFT) calculations suggest that the L10‐PtNi0.8Co0.2 core could tune the surface strain of the Pt shell toward optimized Pt–O binding energy and facilitated reaction rate, thereby improving the ORR electrocatalysis.
Simple Bithiophene–Rhodanine‐Based Small Molecule Acceptor for Use in Additive‐Free Nonfullerene OPVs with Low Energy Loss of 0.51 eV
Authors: Lee Taeho , Eom Yoonho , Song Chang Eun , Jung In Hwan , Kim Dongwook , Lee Sang Kyu , Shin Won Suk , Lim Eunhee 
Published: March 2019

AbstractThe introduction of rigid and extended ladder‐type fused‐ring cores, such as indacenodithiophene, has enabled the synthesis of a variety of nonfullerene small molecules for use as electron acceptors in high‐performance organic photovoltaic cells. Contrasting with recent trends, a very simple‐structured nonfullerene acceptor (NFA), T2‐ORH, consisting of a bithiophene core and octyl‐substituted rhodanine ends, is synthesized in two steps from inexpensive commercially available raw materials. Its relatively short π‐conjugation results in a wide bandgap and a blue‐shifted UV–vis absorption profile complementary to those of poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐co‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th). Despite a sufficient offset between T2‐ORH and PTB7‐Th, the lowest unoccupied molecular orbital (LUMO) energy level of T2‐ORH is still higher than the LUMOs of other NFAs (e.g., ITIC). Therefore, the PTB7‐Th:T2‐ORH blend film exhibits an efficiency of 9.33% with a high open‐circuit voltage of 1.07 V and a short‐circuit current of 14.72 mA cm−2 in an additive‐free single‐junction cell. Importantly, the optimized device displays a remarkably low energy loss of 0.51 eV, in which bimolecular and monomolecular charge recombination is effectively suppressed by solvent vapor annealing treatment. The blend film has a very smooth and homogeneous morphology, providing both vertical and parallel charge transport in the devices.
Tris(pentafluorophenyl)borane‐Assisted Chiral Phosphoric Acid Catalysts for Enantioselective Inverse‐Electron‐Demand Hetero‐Diels‐Alder Reaction of α,β‐Substituted Acroleins
Authors: Hatano Manabu , Sakamoto Tatsuhiro , Mochizuki Takuya , Ishihara Kazuaki 
Published: March 2019

AbstractIn the enantioselective inverse‐electron‐demand hetero‐Diels‐Alder reaction, simple α,β‐unsaturated aldehydes (i. e., acroleins) are still challenging substrates, unlike α,β‐unsaturated carbonyl compounds containing electron‐withdrawing groups. In the present study, the reaction of α‐aryl‐β‐alkyl‐substituted acroleins with ethyl vinyl sulfide was developed with the use of bulky chiral supramolecular Brønsted acid catalysts, such as tris(pentafluorophenyl)borane‐assisted chiral phosphoric acid catalysts. As a result, cis‐cycloadducts as optically active 3,4‐dihydro‐2H‐pyrans were exclusively obtained in high yields with high enantioselectivities via the favored endo orbital approach. An obtained optically active cis‐isomer could be transformed into the corresponding trans‐isomer without a loss of enantiopurity by O,S‐acetal epimerization. Moreover, transformations to synthetically useful optically active epoxide and δ‐valerolactone are also demonstrated.
Photocatalyzed Cyanodifluoromethylation of Alkenes
Authors: Zhang Min , Lin Jin‐Hong , Xiao Ji‐Chang 
Published: March 2019

AbstractDifluoromethylation is a straightforward and widely applied strategy used to incorporate HCF2 into organic molecules. In contrast, cyanation reagents are typically volatile or highly toxic, or they require harsh reaction conditions. Incorporation of both CN and HCF2 into organic molecules, such as alkenes, is a worthwhile but challenging task. A method for photocatalyzed cyanodifluoromethylation of alkenes has been developed, which employs a Ph3P+CF2CO2−/NaNH2 (or NH3) reagent system. Ph3P+CF2CO2− functions as both the HCF2 and CN carbon source. A cyanide anion is generated in situ under mild conditions, thereby avoiding the use of toxic cyanation reagents. The photocatalytic method permits cyanodifluoromethylation of a range of alkenes under mild room temperature conditions. The CN group within the products may be further derivatized by standard methods.
Visible‐Light‐Driven Water Oxidation with a Polyoxometalate‐Complexed Hematite Core of 275 Iron Atoms
Authors: Chakraborty Biswarup , Gan‐Or Gal , Duan Yan , Raula Manoj , Weinstock Ira A. 
Published: March 2019

AbstractAlthough metal oxide nanocrystals are often highly active, rapid aggregation (particularly in water) generally precludes detailed solution‐state investigations of their catalytic reactions. This is equally true for visible‐light‐driven water oxidation with hematite α‐Fe2O3 nanocrystals, which bridge a conceptual divide between molecular complexes of iron and solid‐state hematite photoanodes. We herein report that the aqueous solubility and remarkable stability of polyoxometalate (POM)‐complexed hematite cores with 275 iron atoms enable investigations of visible‐light‐driven water oxidation at this frontier using the versatile toolbox of solution‐state methods typically reserved for molecular catalysis. The use of these methods revealed a unique mechanism, understood as a general consequence of fundamental differences between reactions of solid‐state metal oxides and freely diffusing “fragments” of the same material.
Gegensätzliche Reaktionsweisen magnesium‐ und zinkbasierter Germaniumnukleophile in der C(sp3)‐Ge‐Kreuzkupplung mit Alkylelektrophilen
Authors: Xue Weichao , Mao Wenbin , Zhang Liangliang , Oestreich Martin 
Published: March 2019

AbstractEs wird über robuste Reaktionsvorschriften zweier mechanistisch ungleicher C(sp3)‐Ge‐Bindungsknüpfungen ausgehend von Alkylelektrophilen und Germaniumnukleophilen berichtet. Die Germaniumreagenzien stehen nach Lithium‐auf‐Magnesium‐ bzw. Lithium‐auf‐Zink‐Ummetallierung als stabile Stammlösungen zur Verfügung. Das Germanium‐Grignard‐Reagens reagiert mit mehreren 1° und 2° Alkylelektrophilen in einem ionischen nukleophilen Austausch. Im Gegensatz dazu erfordert die Kupplung des entsprechenden Zinkreagens einen Nickelkatalysator, und jenes nimmt dann an radikalischen Bindungsknüpfungen mit 1°, 2° und selbst 3° Alkylbromiden teil. Beide Methoden umgehen das Regioselektivitätsproblem der Hydrogermylierung von Alkenen und ermöglichen die Darstellung einer breiten Palette funktionalisierter alkylsubstituierter Germane.
Photoprintable nanowire–polymer blends synthesized by dynamic emulsion polycondensation
Authors: Zhang Linqi , Karumuri Sriharsha , Alavi S. Habib , Bai He , Harimkar Sandip P. , Kalkan A. Kaan 
Published: March 2019

ABSTRACTIn this article, we report a photoprintable nanocomposite synthesized at room temperature in less than 10 s by aggressive mixing of two monomer solutions. Polycondensation occurs in the dispersed phase of the dynamic emulsion, microdroplets, in which the nanofillers are suspended. Hence, the synthesized composite microparticles have a high dispersion and high loading of nanofillers. Specifically, silver nanowire (AgNW)–nylon 66 blends with various Ag weight fractions are synthesized and studied. The poly(vinyl pyrrolidone) (PVP)‐functionalized AgNWs (by polyol synthesis) are singly dispersed and tethered to the nylon matrix by PVP with a slight depression of the glass‐transition temperature. The Ag–nylon powder melts under low‐intensity visible continuous wave laser radiation; this allows convenient photoprinting of the nanocomposite structures. Photoprinting is demonstrated at a radiation intensity of 0.3 kW/cm2 (405 nm laser) and a scan rate of 5 mm/s for a 1.49 wt % Ag content. This enhanced photothermal characteristic of the nanocomposite, which allows printing at low radiation intensities, is attributed to the efficient coupling of light to the AgNW plasmon modes and the high dispersion of nanowires in the polymer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47670.
Creep performance of CNT reinforced glass fiber/epoxy composites: Roles of temperature and stress
Authors: Nomula Sai Seetha Ram , Rathore Dinesh Kumar , Ray Bankim Chandra , Prusty Rajesh Kumar 
Published: March 2019

ABSTRACTCarbon nanotubes (CNTs) have been emerged as a potential nanofiller to reinforce polymeric materials to improve their mechanical properties, like strength and modulus. However, time‐dependent deformation of such materials under a constant load and elevated temperature is a matter of concern for long‐term durability of these materials. The present article primarily demonstrates the effects of creep temperature and stress on the reinforcement efficiency of CNT in a glass fiber/epoxy (GE) composite. Two types of materials were investigated in this study—GE which was used as a control material, as well as CNT embedded GE composite. To elucidate the impact of CNT on the long‐term durability of GE composite, creep tests have been performed at different temperatures (50, 80, and 110 °C) under bending loading. As applied stress has also significant contribution toward the elevated creep deformation of materials, creep tests have also been carried out under different stresses (5, 10, and 40 MPa). The strength of the CNT‐GE composite exhibited 8.7 and 18.3% higher than that of control GE composite under tensile and bending load, respectively. Results suggest CNT reinforcement to be beneficial for low temperature applications, both in terms of creep strain and strain rate. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47674.
IR spectroscopy: Suitable method for determination of curing degree and crosslinking type in melamine–formaldehyde resins
Authors: Weiss Stephanie , Urdl Katharina , Mayer Hermann A. , Zikulnig‐Rusch Edith M. , Kandelbauer Andreas 
Published: March 2019

ABSTRACTMelamine–formaldehyde (MF) resins are widely used as adhesives and finishing materials in the wood industry. During resin cure, either methylene ether or methylene bridges are formed, leading to the formation of a three‐dimensional resin network. Not only the curing degree, but also the chemical species present in the cured resin determine the quality of the final product. Analytical methods allowing a detailed investigation of network formation are of great benefit to manufacturers. In the present work, resin cure of an MF precondensate is studied at different temperatures (100–200 °C) without considering the initial pH as a factor. Isoconversional kinetic analysis based on exothermal curing enthalpies enables calculation of the crosslinking degree at a given time/temperature regime. A semiquantitative determination of the chemical groups present is performed based on solid‐state nuclear magnetic resonance data. Fourier transform infrared spectroscopy has shown to be a fast and reliable analytical tool with high sensitivity toward functional groups and with great potential for at‐line process control. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47691.
Normal frailty probit model for clustered interval‐censored failure time data
Authors: Wu Haifeng , Wang Lianming 
Published: March 2019

AbstractClustered interval‐censored data commonly arise in many studies of biomedical research where the failure time of interest is subject to interval‐censoring and subjects are correlated for being in the same cluster. A new semiparametric frailty probit regression model is proposed to study covariate effects on the failure time by accounting for the intracluster dependence. Under the proposed normal frailty probit model, the marginal distribution of the failure time is a semiparametric probit model, the regression parameters can be interpreted as both the conditional covariate effects given frailty and the marginal covariate effects up to a multiplicative constant, and the intracluster association can be summarized by two nonparametric measures in simple and explicit form. A fully Bayesian estimation approach is developed based on the use of monotone splines for the unknown nondecreasing function and a data augmentation using normal latent variables. The proposed Gibbs sampler is straightforward to implement since all unknowns have standard form in their full conditional distributions. The proposed method performs very well in estimating the regression parameters as well as the intracluster association, and the method is robust to frailty distribution misspecifications as shown in our simulation studies. Two real‐life data sets are analyzed for illustration.
Environmentally sustainable or economically sustainable? The effect of Chinese manufacturing firms' corporate sustainable strategy on their green performances
Authors: Yang Morgan X. , Li Ji , Yu Irina Y. , Zeng Kevin J. , Sun Jian‐Min (James) 
Published: March 2019

AbstractEnvironmentally and economically sustainable strategies are predicted to influence the public perception of a firm's green performance in terms of environmental protection as well as corporate social responsibility as a whole. We empirically tested this prediction with the data from 214 Chinese manufacturing firms. Our empirical findings showed that firms' environmentally sustainable strategies are more important compared with the economic ones in shaping firms' green performances. Moreover, we also found a significant moderating effect of employees' education on the relationship between the two sustainable strategies and firms' green performances. We explain the findings and conclude with a discussion of the implications of our findings for academic researchers and practitioners.
Corporate sustainability and institutional shareholders: The pressure of social responsible pension funds on environmental firm practices
Authors: Alda Mercedes 
Published: March 2019

AbstractThis paper analyses the role of social responsible (SR) pension funds as influential institutional shareholders in the corporate sustainability of investee firms. We study the influence of 197 UK SR pension funds on 1,253 firms with 31 environmental, social, and governance (ESG) indicators from 2002 to 2018. According to the indicator nature, we perform logit and ordinary least square (OLS) estimations with panel error correction models to control causality. Our results show that SR pension funds significantly impact on 41.93% of the ESG indicators studied. We find that larger pension‐fund shareholding positively influences on ESG firm performance and encourages proactive behaviour towards environmental practices. Firms with larger pension‐fund shareholding are more likely to use renewable energies and disclose environmental information, increasing the firm transparency towards stakeholders. This study contributes to understand that, besides stakeholders, institutional shareholders (SR pension funds) demand sustainable development and are able to transfer important values for the society and the environment to corporate governance.