bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiresponsive Wettability Switching on Polymer Surface: Effect of Surface Chemistry and/or Morphology Tuning
Authors: Guselnikova Olga , Postnikov Pavel , Elashnikov Roman , Svorcik Vaclav , Lyutakov Oleksiy 
Published: February 2019

AbstractThe design of responsive surfaces with reversible and fast wettability switching by external control represents one of the most urgent challenges in the surface and interfaces sciences. Especially surfaces responding to more than one stimulus are expected to find even broader range of applications. In this paper, a multiresponsive polymer surface is proposed and investigated that is able to respond to the pH, temperature, and electric field. The surface triggering is subdivided into chemically‐based (pH and temperature) and morphologically‐based (application of electric field). The various combinations of three external triggering are applied separately, conjunctively, or adversarily for detailed investigation of their joint action effect. It is found that the most significant changes in wettability switching are achieved by the simultaneous combination of the reversible chemistry and morphology switching. Oppositely, the utilization of the wettability switching through the combination of chemical stimuli produces negative interference of surface response, with the suppression of stimuli efficiency.
Nonaromatic Amine Containing Exciplex for Thermally Activated Delayed Fluorescent Electroluminescence
Authors: Cai Xinyi , Qiu Weidong , Li Mengke , Li Binbin , Wang Zhiheng , Wu Xiao , Chen Dongcheng , Jiang Xiaofang , Cao Yong , Su Shi‐Jian 
Published: February 2019

AbstractA novel nonaromatic amine containing hole‐transporting material, 3,3′‐(2‐methyl‐1,3‐phenylene)diphenoxathiine (mPXTMP), is developed and coevaporated with electron‐transporting materials to form comixed films. Pure‐blue, sky‐blue, and green thermally activated delayed fluorescent (TADF) exciplex emissions are observed. Though the mPXTMP:2,4,6‐tri([1,1′‐biphenyl]‐3‐yl)‐1,3,5‐triazine (T2T) bimolecular system exhibits a large singlet–triplet splitting energy (ΔEST) of 0.44 eV, its locally triplet excited states play vital roles in the cascade up‐conversion process, leading to an abnormal synergistic enhancement of TADF and phosphorescence from high‐lying triplet states at a low temperature, which violates Kasha's rule. Another bimolecular system, mPXTMP:PO‐T2T, achieves a fast up‐conversion rate of 106 s−1 benefiting from a small ΔEST of 0.10 eV and the enhanced spin–orbital coupling induced by the sulfur element rich environment. The corresponding organic light‐emitting diodes realize an exciton utilization ratio of 61.7–92.6%, verifying that these nonaromatic amine containing exciplex systems can be promising candidates toward purely organic electroluminescence with 100% internal quantum efficiency.
Spectrally Tunable Solid State Fluorescence and Room‐Temperature Phosphorescence of Carbon Dots Synthesized via Seeded Growth Method
Authors: Zhu Jinyang , Bai Xue , Chen Xu , Shao He , Zhai Yue , Pan Gencai , Zhang Hanzhuang , Ushakova Elena V. , Zhang Yu , Song Hongwei , Rogach Andrey L. 
Published: February 2019

AbstractA seeded growth method to produce colloidal carbon dots (CDs) through controlling the number of seeds and reaction time, which is demonstrated to be an effective way to tune their optical properties, is developed. Color‐tunable fluorescence of CDs with blue, green, yellow, and orange emissions under UV excitation is achieved by increasing the size of the seed CDs, with the color depending on the size of the π‐conjugated domains. Strong multicolor photoluminescence of powdered samples enables realization of efficient down‐conversion white‐light‐emitting devices with correlated color temperature ranging from 9579 to 2752 K and luminous efficacy from 19 to 51 lm W−1. Moreover, color‐tunable room‐temperature phosphorescence of CD powders is demonstrated in the broad spectral range of 500–600 nm. It is related to the presence of the nitrogen‐containing groups at the surface of CDs, which form interparticle hydrogen bonds to protect the CD triplet states from quenching, and to the existence of the polyvinylpyrrolidone polymer chains at the surface of CDs. The color‐tunable room‐temperature phosphorescence from CDs demonstrated in this work exhibits potential for data encryption.
Highly Luminescent Cesium Lead Halide Perovskite Nanocrystals Stabilized in Glasses for Light‐Emitting Applications
Authors: Ye Ying , Zhang Wenchao , Zhao Zhiyong , Wang Jing , Liu Chao , Deng Zhao , Zhao Xiujian , Han Jianjun 
Published: February 2019

AbstractCesium lead halide (CsPbX3) nanocrystals have great potential for photovoltaic and optoelectronic applications, but they are sensitive to oxygen, moisture, and light irradiation. Embedding these CsPbX3 nanocrystals into all‐inorganic amorphous solid matrices such as glass is expected to improve their stability. In this work, CsPbX3 nanocrystals are precipitated in boro‐germanate glasses with tunable composition, absorption, and photoluminescence. Quantum efficiency of CsPbBr3 nanocrystals in glass can be as high as ≈80% and ≈20% for CsPb(Cl/Br)3 and CsPb(Br/I)3 nanocrystals, respectively. Thermo‐ and photostabilities of CsPbX3 nanocrystals in glass are greatly improved due to the inert nature of glasses, and intense laser irradiation‐induced damage to CsPbX3 nanocrystals is recoverable through thermal annealing. With CsPbBr3 nanocrystal‐embedded glass slices, a green light‐emitting device with a luminous efficiency of ≈120 lm W−1 and an external quantum yield of ≈30% is achieved. A white‐light‐emitting device consisting of CsPbBr3 nanocrystals and CsPb(Br/I)3 nanocrystal–embedded glass slices shows luminous efficiency in the range of 50–60 lm W−1 and external quantum yield of 20–25%. The thermo‐ and photostabilities along with the chemical stability of CsPbX3 nanocrystal–embedded glasses are promising materials for photoluminescence related applications.
Reducing the Chromaticity Shifts of Light‐Emitting Diodes Using Gradient‐Alloyed CdxZn1−xSeyS1−y@ZnS Core Shell Quantum Dots with Enhanced High‐Temperature Photoluminescence
Authors: Tang Jialun , Li Fei , Yang Gaoling , Ge Yong , Li Zhaohan , Xia Zhiguo , Shen Huaibin , Zhong Haizheng 
Published: February 2019

AbstractGradient‐alloyed CdxZn1−xSeyS1−y@ZnS core shell quantum dots are the most popular materials used in light‐emitting diodes for liquid crystal display backlights. High‐temperature photoluminescence is an essential property in determining the chromaticity shifts of on‐chip type devices. In this work, the photoluminescence quenching effect of CdxZn1−xSeyS1−y@ZnS quantum dots is investigated by measuring the steady and time‐resolved PL spectra at elevated temperatures. The thermal quenching of CdxZn1−xSeyS1−y@ZnS quantum dots can be explained by a thermally activated physical process, including electron resonance tunneling into pre‐existing surface trap states, injection over the barrier energy back to the core, and recombination with the confined holes. By combing the theoretical analysis and experimental results, the influence of core composition and shell thickness of CdxZn1−xSeyS1−y@ZnS QDs on the quenching effect is illustrated. It is found that the integrated photoluminescence intensity of ZnSe‐rich quantum dots with 20 monolayers ZnS shell at 500 K can reserve 85.1%, relative to the value at 300 K. Quantum dots with enhanced photoluminescence emission at high temperature enable the fabrication of light‐emitting diodes with reduced chromaticity shifts.
Bluish‐Green Thermally Activated Delayed Fluorescence Material for Blue‐Hazard Free Hybrid White Organic Light‐Emitting Device with High Color Quality and Low Efficiency Roll‐Off
Authors: Wang Hui , Zang Chunxiu , Shan Guogang , Yu Ziwei , Liu Shihao , Zhang Letian , Xie Wenfa , Zhao Hongyu 
Published: February 2019

AbstractHigh color quality and the removal of blue hazard are important for lighting applications. Thermally activated delayed fluorescence (TADF) materials can achieve ≈100% internal quantum efficiency with low cost. However, it is still challenging to achieve high‐color‐quality and blue‐hazard‐free TADF‐based white organic light‐emitting devices (WOLEDs). Here, a bluish‐green TADF material named 10,10′‐[5‐(6‐[1,1′‐biphenyl]‐4‐yl‐2‐phenyl‐4‐pyrimidinyl)‐1,3‐phenylene] bis [9,10‐dihydro‐9,9‐dimethyl‐acridine (DMAC‐BPP) containing two acridines connecting by a phenyl and a pyrimidine is designed and synthesized. Efficient bluish‐green OLED is achieved with DMAC‐BPP emitter. Besides, the yellow and red phosphorescent OLED utilizing DMAC‐BPP as host also shows excellent performance. Thus, a blue‐hazard‐free hybrid WOLED using DMAC‐BPP as host and emitter with maximum external quantum efficiency of 15.6% is achieved. Furthermore, this WOLED shows low efficiency roll‐off and high color quality.
Exciton Diffusion Lengths and Dissociation Rates in CsPbBr3 Nanocrystal–Fullerene Composites: Layer‐by‐Layer versus Blend Structures
Authors: Yao En‐Ping , Bohn Bernhard J. , Tong Yu , Huang He , Polavarapu Lakshminarayana , Feldmann Jochen 
Published: February 2019

AbstractSolution‐processable perovskite nanocrystals (NCs) are gaining increasing interest in the field of photovoltaics because of their enhanced stability compared to their thin‐film counterparts. However, the charge transfer dynamics in perovskite NC based light‐harvesting systems are not well understood. By applying femtosecond differential transmission (DT) spectroscopy the photoinduced charge transfer from inorganic perovskite CsPbBr3 NCs to the fullerene derivative phenyl‐C61‐butyric acid methyl ester (PCBM) is investigated for two fundamentally different architectures, namely layer‐by‐layer heterostructures and blend structures. By varying the thickness of the NC layer on top of the PCBM in the layer‐by‐layer heterostructure, an exciton diffusion length of 290 ± 28 nm for CsPbBr3 NC is extracted. The diffusion process is followed by an ultrafast exciton dissociation (within 200 fs) at the CsPbBr3 NC/PCBM interface. In blend structures an overall faster charge transfer process is observed. Furthermore, photoconductivity measurements on a blend structure‐based photodetector reveal an effective charge extraction from the active layer resulting in a high photosensitivity. DT measurements on this blend structure including adjacent electron‐ or hole‐transport layers give insight into the extraction process and suggest a certain degree of phase segregation, which assists the charge collection.
Chiral Anion‐Induced Catalytic Asymmetric Direct Dehydrative Coupling of 3‐Vinylindoles and 3‐Indolylmethanols
Authors: Li Xiao‐Yun , Hu Wei‐Ting , Xiong Qiu‐Ju , Ye Si‐Min , Huang Yan‐Min , Guo Qi‐Xiang 
Published: February 2019

AbstractThe catalytic direct dehydrative coupling of an alkene with an alcohol is one of the most straightforward and green strategies for the formation of Csp2−Csp2 bonds. However, previously reported studies have only dealt with achiral reactions. Here, we describe chiral Brønsted acid‐catalyzed direct catalytic asymmetric dehydrative coupling reactions of 3‐vinylindoles and 3‐indolylmethanols. Various structurally diverse indole compounds were prepared in good to excellent yields, with good to excellent stereoselectivities.magnified image
Interface Engineering via MoS2 Insertion Layer for Improving Resistive Switching of Conductive‐Bridging Random Access Memory
Authors: Wu Facai , Si Shuyao , Cao Peng , Wei Wei , Zhao Xiaolong , Shi Tuo , Zhang Xumeng , Ma Jianwei , Cao Rongrong , Liao Lei , Tseng Tseung‐Yuen , Liu Qi 
Published: February 2019

AbstractConductive‐bridging random access memory (CBRAM), dominated by conductive filament (CF) formation/rupture, has received much attention due to its simple structure and outstanding performances for nonvolatile memory, neuromorphic computing, digital logic, and analog circuit. However, the negative‐SET behavior can degrade device reliability and parameter uniformity. And large RESET current increases power consumption for memory applications. By inserting 2D material, molybdenum disulfide (MoS2), for interface engineering with the device configuration of Ag/ZrO2/MoS2/Pt, the negative‐SET behavior is eliminated, and the RESET current is reduced simultaneously. With the ion barrier property of MoS2, the CF can probably not penetrate the MoS2 layer, thus eliminating the negative‐SET behavior. And with the low thermal conductivity of MoS2, the internal temperature of the device would be relatively high at RESET, accelerating probably redox reactions. As a result, the RESET current is reduced by an order of magnitude. This interface engineering opens up a way in improving the resistive switching performances of CBRAM, and can be of great benefit to the potential applications of MoS2 in next‐generation data storage.
The Observation of Domain‐Wall Current Transients Along with Charge Injection at Elevated Temperatures
Authors: Chen Dongfang , Gu Zongquan , Zhao Dong‐Hui , Bai Zilong , Jiang Anquan 
Published: February 2019

AbstractErasable conductive domain walls (DWs) in insulating ferroelectrics are key components to reconfigurable nanocircuitries, nanosensors, and memories, but the wall currents are found to decay with time, especially at high temperatures. In this study, DW currents are induced upon partial domain switching against the peripheral unswitched bulk domain under the application of in‐plane electric field between two top electrodes patterned on epitaxial BiFeO3 (BFO) thin films. The “on” currents are followed by a drop at higher bias above the coercive voltage, which becomes more significant at elevated temperature from 298 to 408 K. An opposite “on” current is observed in the back sweeping when the above walls are erased to restore the as‐grown, stable domain structure. The phenomenon is explained by a film defect‐related model that free charges are injected and locally trapped at the defect levels to help screen the uncompensated polarizations in the conducting DWs, resulting in the wall current reduction. Once the walls are erased at opposite coercive voltages, the trapped free charges at the conducting DWs are expelled to form a discharge current. This finding provides the fundamental physics of the wall conduction in correlation with the film defects and reversible charge injection.
Occupational exposure and airflow obstruction and self‐reported COPD among ever‐employed US adults using a COPD‐job exposure matrix
Authors: Doney Brent , Kurth Laura , Halldin Cara , Hale Janet , Frenk Steven M. 
Published: February 2019

IntroductionThis study examined the association of spirometry‐defined airflow obstruction and self‐reported COPD defined as self‐reported doctor diagnosed chronic bronchitis or emphysema, with occupational exposure among ever‐employed US adults.MethodsData were obtained from the National Health and Nutrition Examination Survey (NHANES) 2007‐2008 to 2011‐2012, a nationally representative study of the non‐institutionalized civilian US population. Reported current and/or longest held job were used to create prevalence estimates and prevalence odds ratios (PORs) (adjusted for age, gender, race, and smoking status) for airflow obstruction and self‐reported COPD by occupational exposure, determined using both NHANES participants’ self‐reported exposures and eight categories of COPD job exposure matrix (JEM) assigned exposures.ResultsSignificant PORs for airflow obstruction and self‐reported COPD respectively were observed with self‐reported exposure for ≥20 years to mineral dust (POR = 1.44; 95% confidence interval (CI) 1.13‐1.85; POR = 1.69; 95% CI 1.17‐2.43) and exhaust fumes (POR = 1.65; 95% CI 1.27‐2.15; POR = 2.22; 95% CI 1.37‐3.58). Airflow obstruction or self‐reported COPD were also associated with COPD‐JEM assigned high exposure to mineral dust, combined dust, diesel exhaust, vapor‐gas, sensitizers, and overall exposure.ConclusionAirflow obstruction and self‐reported COPD are associated with both self‐reported and JEM‐assigned exposures.
Total Synthesis of (−)‐Alstofolinine A through a Furan Oxidation/Rearrangement and Indole Nucleophilic Cyclization Cascade
Authors: Zhang Lei , Zhang Ye , Li Wenting , Qi Xiangbing 
Published: February 2019

AbstractA reaction cascade of aza‐Achmatowicz rearrangement followed by indole nucleophilic cyclization was developed to generate the common indole‐fused azabicyclo[3.3.1]nonane core of the macroline family alkaloids. The key to the success of the strategy relies on the careful manipulation of protecting groups and judicious selection of chemoselective furan oxidation conditions. The synthetic utility was further demonstrated on the asymmetric total synthesis of (−)‐alstofolinine A.
Core Modulation of 70‐Nuclei Core‐Shell Silver Nanoclusters
Authors: Liu Jia‐Wei , Wang Zhi , Chai Yu‐Ming , Kurmoo Mohamedally , Zhao Quan‐Qin , Wang Xing‐Po , Tung Chen‐Ho , Sun Di 
Published: February 2019

AbstractThe reaction of {(HNEt3)2[Ag10(tBuC6H4S)12]}n, Ag2O, Na2MoO4, and m‐methoxybenzoic acid (Hmbc) in CH3OH/CH2Cl2 led to yellow crystals of [Ag4S4 (MoO4)5@Ag66] (SD/Ag70b; SD=SunDi) only, while in the presence of DMF, additional dark‐red crystals of [Ag10@ (MoO4)7@Ag60] (SD/Ag70a) were obtained. SD/Ag70b consists of five MoO42− ions wrapped by a shell of 66 Ag atoms, while SD/Ag70a contains a rare Ag10 kernel consisting of five tetrahedra sharing faces and edges, surrounded by seven MoO42− ions enclosed in a shell of 60 Ag atoms. The formation of the Ag10 kernel originates from a reduction reaction during the self‐assembly process that involves DMF. This work provides the structural information of a unique Ag10 kernel (five fused Ag4 tetrahedra) and paves an avenue to trap elusive silver species with hierarchical multi‐shell silver nanocluster assemblies with the help of anion templates.
Enhanced Circularly Polarized Luminescence from Reorganized Chiral Emitters on the Skeleton of a Zeolitic Imidazolate Framework
Authors: Zhao Tonghan , Han Jianlei , Jin Xue , Liu Yan , Liu Minghua , Duan Pengfei 
Published: February 2019

AbstractA chiral zeolitic imidazolate framework (ZIF) showing circularly polarized luminescence (CPL) has been successfully constructed by blending binapthyl‐derived chiral emitters with ZIF‐8 rhombic dodecahedron nanoparticles. This approach solves a major trade‐off in CPL‐active materials: the large luminescence dissymmetry factor (glum) always suffers from suppression of luminescence efficiency. Compared to the optical properties of chiral emitters, the obtained chiral ZIF nanomaterials showed an enhanced fluorescence efficiency while the |glum| value is significantly amplified by one order of magnitude. Additionally, enantioselective fluorescence sensing in response to α‐hydroxycarboxylic acids has been enhanced in chiral ZIFs. Reorganization and conjunction of chiral emitters to the skeleton of ZIF nanoparticles can greatly improve both the luminescence quantum yield and circularly polarization, which facilitates the design of more efficient chiroptical materials.
Asymmetric Total Syntheses of the Akuammiline Alkaloids (−)‐Strictamine and (−)‐Rhazinoline
Authors: Li Wenfei , Chen Zhitao , Yu Di , Peng Xin , Wen Guohua , Wang Siqi , Xue Fei , Liu Xiao‐Yu , Qin Yong 
Published: February 2019

AbstractStrictamine and rhazinoline are representative methanoquinolizidine‐containing akuammiline alkaloids that possess different stereochemistry at the C16 position. A unified approach to the enantioselective total syntheses of these two molecules is described. The key steps in this synthesis include a photocatalytic intra/intermolecular type II radical cascade reaction, a Tsuji–Trost allylation, a palladium‐ or nickel‐mediated cyclization, and a late‐stage intramolecular N‐alkylation reaction.
The Dual Role of Benzophenone in Visible‐Light/Nickel Photoredox‐Catalyzed C−H Arylations: Hydrogen‐Atom Transfer and Energy Transfer
Authors: Dewanji Abhishek , Krach Patricia E. , Rueping Magnus 
Published: February 2019

AbstractA dual catalytic protocol for the direct arylation of non‐activated C(sp3)−H bonds has been developed. Upon photochemical excitation, the excited triplet state of a diaryl ketone photosensitizer abstracts a hydrogen atom from an aliphatic C−H bond. This inherent reactivity was exploited for the generation of benzylic radicals which subsequently enter a nickel catalytic cycle, accomplishing the benzylic arylation.
Influence of polymer structure on the gelation kinetics and gel strength of acrylamide‐based copolymers, bentonite and polyethylenimine systems for conformance control of oil reservoirs
Authors: Tessarolli Fernanda G. C. , Souza Sara T. S. , Gomes Ailton S. , Mansur Claudia R. E. 
Published: February 2019

ABSTRACTIn oil reservoirs with conformance problems, the sweep and oil recovery efficiencies tend to be low because the injected oil‐recovery drive fluids channel through high‐permeability zones and/or anomalies, leaving behind part of the displaceable oil in unswept low‐permeability zones. In these scenarios, conformance improvement treatments with crosslinked polymers can be used to plug the main paths of the reservoir, improving the overall sweep efficiency. This study aimed to investigate the influence of the polymer structure [molecular weight, acrylate, 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS), and/or N‐vinyl‐2‐pyrrolidone (NVP) moieties] on the gelation kinetics of gelling systems based on homopolymers and copolymers of acrylamide, natural bentonite and polyethylenimine for the conformance control of reservoirs with harsh conditions of temperature and salinity/hardness. The correspondence between the gelation time and gel strength obtained from bottle tests and dynamic shear tests was evaluated. Samples with higher AMPS and NVP moieties formed strong composite hydrogels (equilibrium complex modulus = 20–40 Pa) with low syneresis, and good long‐term stability (∼3–6 months) under harsh conditions (90 °C, 56,012 mg L−1 total dissolved solids and 2100 mg L−1 of divalent ions). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47556.HIGHLIGHTS

Acrylamide‐based copolymers, bentonite and polyethylenimine systems showed controllable gelation time and gel strength
Addition of clay into the formulation increased the gelation time and syneresis resistance of the systems, and slightly improved the final strength of the composite hydrogels
Polyacrylamide (PAM) and partially hydrolyzed polyacrylamide (PHPA) samples formed heterogeneous composite hydrogels that suffered strong syneresis and thermal degradation, precipitating during aging after approximately 2 months, independently of the initial acrylate moieties of the sample
Acrylamide and 2‐acrylamide‐2‐methylpropane sulfonic acid copolymer (PAM–AMPS) and acrylamide, 2‐acrylamido‐2‐methylpropane sulfonic acid, and N‐vinyl‐2‐pyrrolidone (PAM–AMPS–NVP) samples presented higher salt tolerance and formed composite hydrogels with lower syneresis and good long‐term stability (∼3–6 months). Furthermore, samples with sulfonation degree greater than 10% improved the dispersion of clay particles within the hydrogels' structure