bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure‐Dependent Optical Modulation of Propulsion and Collective Behavior of Acoustic/Light‐Driven Hybrid Microbowls
Authors: Tang Songsong , Zhang Fangyu , Zhao Jing , Talaat Wael , Soto Fernando , Karshalev Emil , Chen Chuanrui , Hu Zhihan , Lu Xiaolong , Li Jinxing , Lin Zhihua , Dong Haifeng , Zhang Xueji , Nourhani Amir , Wang Joseph 
Published: April 2019

AbstractHybrid light/acoustic‐powered microbowl motors, composed of gold (Au) and titanium dioxide (TiO2) with a structure‐dependent optical modulation of both their movement and collective behavior are reported by reversing the inner and outer positions of Au and TiO2. The microbowl propels in an acoustic field toward its exterior side. UV light activates the photochemical reaction on the TiO2 surface in the presence of hydrogen peroxide and the Au/TiO2 system moves toward its TiO2 side by self‐electrophoresis. Controlling the light intensity allows switching of the dominant propulsion mode and provides braking or reversal of motion direction when TiO2 is on the interior, or accelerated motion when the TiO2 is on its exterior. Theoretical simulations offer an understanding of the acoustic streaming flow and self‐electrophoretic fluid flow induced by the asymmetric distribution of ions around the microbowl. The light‐modulation behavior along with the tunable structure also leads to the control of the swarm behaviors under the acoustic field, including expansion or compaction of ensembles of microbowls with interior and exterior TiO2, respectively. Such structure‐dependent motion control thus paves the way for a variety of complex microscale operations, ranging from cargo transport to drug delivery in biomedical and environmental applications.
Screen‐Printed Soft Capacitive Sensors for Spatial Mapping of Both Positive and Negative Pressures
Authors: Shi Hongyang , Al‐Rubaiai Mohammed , Holbrook Christopher M. , Miao Jinshui , Pinto Thassyo , Wang Chuan , Tan Xiaobo 
Published: April 2019

AbstractSoft pressure sensors are one class of the essential devices for robotics and wearable device applications. Despite the tremendous progress, sensors that can reliably detect both positive and negative pressures have not yet been demonstrated. In this paper, a soft capacitive pressure sensor, made using a convenient and low‐cost screen‐printing process that can reliably detect both positive and negative pressures from −60 to 20 kPa, is reported. The sensor is made with an Ecoflex‐0030 dielectric layer, conductive and stretchable poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (with ionic additives) electrodes, and polydimethylsiloxane encapsulation layers. Air gaps are designed and incorporated into the dielectric layer to significantly enhance the sample deformation and pressure response especially to negative pressure. The sensor exhibits repeatable response for thousands of cycles, even under bending or stretching conditions. Lastly, to demonstrate the practical application, a 12 × 12‐pixel sensor array that can automatically measure both positive and negative pressure distributions has been reported under −20 and 10 kPa.
High‐Temperature Photochromism of Fe‐Doped SrTiO3 Caused by UV‐Induced Bulk Stoichiometry Changes
Authors: Viernstein Alexander , Kubicek Markus , Morgenbesser Maximilian , Walch Gregor , Brunauer Georg Christoph , Fleig Jürgen 
Published: April 2019

AbstractThe impact of UV irradiation on Fe‐doped SrTiO3 (Fe:STO) single crystals is investigated at elevated temperatures. Illumination leads to incorporation of oxygen into the single crystals and thus to a decreasing oxygen vacancy concentration and oxidation of Fe3+ to Fe4+. The Fe4+ ions cause a color change from transparent/brownish to black. This photochromic blackening due to stoichiometry changes at elevated temperatures is irreversible at room temperature, but annealing at high temperatures, for example at 700 °C, can restore the original stoichiometry and color. Absorbance changes due to UV irradiation are monitored by ex situ and in situ UV–vis spectroscopy experiments and changes in electrical properties are measured by van der Pauw measurements and in‐plane electrochemical impedance spectroscopy. After 1140 min of illumination at 440 °C, for example, electrical measurements reveal a conductivity increase by more than a factor of 5 due to the enhanced hole concentration in blackened Fe:STO. In addition, UV illumination increases the oxygen chemical potential up to a calculated p(O2) of more than 109 Pa in Fe:STO. Hence, UV light can be used to tune the color, but also electrical properties of Fe:STO by directly impacting the bulk defect concentrations.
Band Gap Engineering Improves the Efficiency of Double Quantum Dot Upconversion Nanocrystals
Authors: Yang Gaoling , Meir Noga , Raanan Dekel , Oron Dan 
Published: April 2019

AbstractSolution‐processed core/multishell semiconductor quantum dots (QDs) could be tailored to facilitate the carrier separation, promotion, and recombination mechanisms necessary to implement photon upconversion. In contrast to other upconversion schemes, upconverting QDs combine the stability of an inorganic crystalline structure with the spectral tunability afforded by quantum confinement. Nevertheless, their upconversion quantum yield (UCQY) is fairly low. Here, design rules are uncovered that enable to significantly enhance the performance of double QD upconversion systems, and these findings are leveraged to fabricate upconverting QDs with increased photon upconversion efficiency and reduced saturation intensities under pulsed excitation. The role of the intra‐QD band alignment is exemplified by comparing the upconversion process in PbS/CdS/ZnSe QDs with that of PbS/CdS/CdSe ones with variable CdSe shell thicknesses. It is shown that electron delocalization into the shell leads to a longer‐lived intermediate state in the QDs, facilitating further absorption of photons, and enhancing the upconversion process. The performance of these upconversion QDs under pulsed excitation versus continuous pumping is also compared; the reasons for the significant differences between these two regimes are discussed. The results show how one can overcome some of the limitations of previous upconverting QDs, with potential applications in biophotonics and infrared detection.
Beetle‐Inspired Assembly of Heterostructured Lamellar Membranes with Polymer Cluster–Patterned Surface for Enhanced Molecular Permeation
Authors: Wang Jingtao , Yuan Zhijie , Wu Xiaoli , Li Yifan , Chen Jingjing , Jiang Zhongyi 
Published: April 2019

Abstract2D lamellar membranes hold great promise in efficient molecular separations of liquid and gas mixtures. However, the simultaneous realization of high permeation and precise sieving (i.e., overcoming the permeation–rejection tradeoff) of membranes poses a great challenge. Inspired by the structures and functions of the beetle's back, the heterostructured lamellar membranes fabricated through facile and controllable electrostatic atomization method are reported. Particularly, hydrophobic polymer clusters are patterned on hydrophilic laminate (graphene oxide) surfaces to realize the hydrophilic/hydrophobic heterostructure. It shows that the fast dissolution for nonpolar solvents is achieved by the strong affinity polymer clusters, and the ultralow‐barrier diffusion is achieved by the weak affinity laminate channels. Therefore, the permeance is remarkably enhanced (over 7 times for nonpolar solvents), while fully retaining membrane rejection. In contrast, hydrophilic clusters are patterned on hydrophobic laminate (reduced graphene oxide) surfaces and exhibit similar behaviors toward polar solvents. Furthermore, the lamellar membrane displays highly ordered layer‐by‐layer stacking, affording precise molecular rejection. Besides, the lamellar membrane acquires lower thermodynamic energy and hence superior stability under ultrasonic and strong acid or alkali environments, manifesting great potential for long‐term practical operation.
Intercalated Electrolyte with High Transference Number for Dendrite‐Free Solid‐State Lithium Batteries
Authors: Chen Long , Li Wenxin , Fan Li‐Zhen , Nan Ce‐Wen , Zhang Qiang 
Published: April 2019

AbstractSolid‐state lithium (Li) batteries using solid electrolytes and Li anodes are highly desirable because of their high energy densities and intrinsic safety. However, low ambient‐temperature conductivity and poor interface compatibility of solid electrolytes as well as Li dendrite formation cause large polarization and poor cycling stability. Herein, a high transference number intercalated composite solid electrolyte (CSE) is prepared by the combination of a solution‐casting and hot‐pressing method using layered lithium montmorillonite, poly(ethylene carbonate), lithium bis(fluorosulfonyl)imide, high‐voltage fluoroethylene carbonate additive, and poly(tetrafluoroethylene) binder. The electrolyte presents high ionic conductivity (3.5 × 10−4 S cm−1), a wide electrochemical window (4.6 V vs Li+/Li), and high ionic transference number (0.83) at 25 °C. In addition, a 3D Li anode is also fabricated via a facile thermal infusion strategy. The synergistic effect of high transference number intercalated electrolyte and 3D Li anode is more favorable to suppress Li dendrites in a working battery. The solid‐state batteries based on LiFePO4 (Al2O3 @ LiNi0.5Co0.2Mn0.3O2), CSE, and 3D Li deliver admirable cycling stability with discharge capacity 145.9 mAh g−1 (150.7 mAh g−1) and capacity retention 91.9% after 200 cycles at 0.5 C (92.0% after 100 cycles at 0.2 C) at 25 °C. This work affords a splendid strategy for high‐performance solid‐state battery.
One‐Step Fabrication of Ultralow Pt Loading High Efficiency Proton Exchange Membrane for Water Electrolysis by Conventional E‐Beam Metal Deposition
Authors: Wang Yanyan , Yu Xue , Liu Gen , Zhu Xiaodong , Xu Rui , Ji Mei , Ma Yanqing , Ma Lei 
Published: April 2019

AbstractProton exchange membrane water electrolysis (PEMWE) is known as an effective and environmental‐friendly method for hydrogen production. However, the process is hindered by the necessity of large loading of high‐priced noble metals in the conventional approaches. To resolve this problem, a highly efficient Nafion‐based catalyst and proton exchange system are developed, which only need ultralow platinum loading by direct e‐beam evaporation deposition. Scanning electron microscopy is performed before and after the deposition, which reveals a very smooth morphology. By assembling the PEMWE device with above‐mentioned cathode and conventional iridium black anode, the current density reaches 500 mA cm−2 with a platinum loading of only 0.00379 mg cm−2 at 1.64 V under 80 °C. A mass activity of ≈132 A mg−1 is achieved, which is one order of magnitude higher than previously reported results. Moreover, powered by a commercial silicon solar cell, it realizes a solar‐to‐hydrogen conversion efficiency up to 8.26%. This work opens up an avenue of fabricating PEMWE with an ultralow catalyst loading, which may have enormous potential for future industrial scale applications.
Effect of Constituent Materials on Composite Performance: Exploring Design Strategies via Machine Learning
Authors: Chen Chun‐Teh , Gu Grace X. 
Published: April 2019

AbstractNature assembles a range of biological composites with remarkable mechanical properties despite being composed of relatively weak polymeric and ceramic components. However, the architectures of biomaterials cannot be considered as optimal designs for engineering applications since biomaterials are constantly evolving for multiple functions beyond carrying external loading. Here, it is aimed to develop an intelligent approach to design superior composites from scratch—starting from constituent materials. A systematic computational investigation of the effect of constituent materials (assumed to be perfectly brittle) on the behavior of composites using an integrated approach combining finite element method, molecular dynamics, and machine learning (ML) is reported. It is demonstrated that instead of using brute‐force methods, machine learning is a much more efficient approach and can generate optimal designs with similar performance to those obtained from an exhaustive search. Furthermore, it is shown that the toughening and strengthening mechanism observed in composites at the continuum‐scale by combining stiff and soft constituents is valid for nanomaterials as well. Results show that high‐performing designs of graphene nanocomposites can be generated using our ML approach. This novel ML‐based design framework can be applied to other material systems to study a variety of structure–property relationships over several length‐scales.
Synergy of Nb Doping and Surface Alloy Enhanced on Water–Alkali Electrocatalytic Hydrogen Generation Performance in Ti‐Based MXene
Authors: Du Cheng‐Feng , Sun Xiaoli , Yu Hong , Liang Qinghua , Dinh Khang Ngoc , Zheng Yun , Luo Yubo , Wang Zhiguo , Yan Qingyu 
Published: April 2019

AbstractPresented are the theoretical calculation and experimental studies of a Ti3C2Tx MXene‐based nanohybrid with simultaneous Nb doping and surface transition metal alloy modification. Guided by the density functional theory calculation, the Nb doping can move up the Fermi energy level to the conduction band, thus enhancing the electronic conductivity. Meanwhile, the surface modification by Ni/Co alloy can moderate the surface M–H affinity, which will further enhance the hydrogen evolution reaction (HER) activity. A series of Ni/Co alloy attached on Nb‐doped Ti3C2Tx MXene nanohybrids (denoted as NiCo@NTM) are successfully prepared. As expected, the Ni0.9Co0.1@ NTM nanohybrids present an extraordinary HER activity in alkaline solution, which only needs an overpotential (η) of 43.4 mV to reach the current density of 10 mA cm−2 in 1 m KOH solution and shows good stability. The performance of the Ni0.9Co0.1@ NTM nanohybrids is comparable to the commercial 10% Pt/C electrode (34.4 mV@10 mA cm−2) and is better than most state‐of‐the‐art Pt‐free HER catalysts. Inspired by the facile synthesis process and chemical versatility of both MXene and transition metal alloys, the nanohybrids reported here are promising non‐noble metal electrocatalysts for water–alkali electrolysis.
Quantitative Third Harmonic Generation Microscopy for Assessment of Glioma in Human Brain Tissue
Authors: Zhang Zhiqing , de Munck Jan C. , Verburg Niels , Rozemuller Annemieke J. , Vreuls Willem , Cakmak Pinar , van Huizen Laura M. G. , Idema Sander , Aronica Eleonora , de Witt Hamer Philip C. , Wesseling Pieter , Groot Marie Louise 
Published: April 2019

AbstractDistinguishing tumors from normal brain cells is important but challenging in glioma surgery due to the lack of clear interfaces between the two. The ability of label‐free third harmonic generation (THG) microscopy in combination with automated image analysis to quantitatively detect glioma infiltration in fresh, unprocessed tissue in real time is assessed. The THG images reveal increased cellularity in grades II–IV glioma samples from 23 patients, as confirmed by subsequent hematoxylin and eosin histology. An automated image quantification workflow is presented for quantitative assessment of the imaged cellularity as a reflection of the degree of glioma invasion. The cellularity is validated in three ways: 1) Quantitative comparison of THG imaging with fluorescence microscopy of nucleus‐stained samples demonstrates that THG reflects the true tissue cellularity. 2) Thresholding of THG cellularity differentiates normal brain from glioma infiltration, with 96.6% sensitivity and 95.5% specificity, in nearly perfect (93%) agreement with pathologists. 3) In one patient, a good correlation between THG cellularity and preoperative magnetic resonance and positron emission tomography imaging is demonstrated. In conclusion, quantitative real‐time THG microscopy accurately assesses glioma infiltration in ex vivo human brain samples, and therefore holds strong potential for improving the accuracy of surgical resection.
Phase‐Transited Lysozyme‐Driven Formation of Self‐Supported Co3O4@C Nanomeshes for Overall Water Splitting
Authors: Ha Yuan , Shi Lingxia , Chen Ziliang , Wu Renbing 
Published: April 2019

AbstractThe development of highly efficient catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of paramount importance in water splitting. Herein, a phase‐transited lysozyme (PTL) is employed as the platform to synthesize nitrogen‐doped Co3O4@C nanomesh with rich oxygen vacancies supported on the nickel foam (N‐Co3O4@C@NF). This PTL‐driven N‐Co3O4@C@NF integrates the advantages of porous structure, high exposure of surface atoms, strong synergetic effect between the components and unique 3D electrode configuration, imparting exceptional activity in catalyzing both HER and OER. Remarkably, an alkaline electrolyzer assembled by N‐Co3O4@C@NF as both cathode and anode delivers a current density of 10 mA cm−2 at an ultralow cell voltage of 1.40 V, which is not only much lower than that of the commercially noble Pt/C and IrO2/C catalyst couple (≈1.61 V) but also a new record for the overall water splitting. The finding may open new possibilities for the design of bifunctional electrocatalysts for application in practical water electrolysis.
Energy Transfer between Tb3+ and Eu3+ in LaPO4: Pulsed versus Switched‐off Continuous Wave Excitation
Authors: Luo Yuxia , Liu Zhenyu , Wong Hon Tung , Zhou Lei , Wong Ka‐Leung , Shiu Kwok Keung , Tanner Peter A. 
Published: April 2019

AbstractThe energy transfer (ET) between Tb3+ and Eu3+ is investigated experimentally and with available theoretical models in the regime of high Tb3+ concentrations in ≈30 nm LaPO4 nanoparticles at room temperature. The ET efficiency approaches 100% even for lightly Eu3+‐doped materials. The major conclusion from the use of pulsed laser excitation and switched‐off continuous wave laser diode excitation is that the energy migration between Tb3+ ions, situated on La3+ sites with ≈4 Å separation, is not fast. The quenching of Tb3+ emission in singly doped LaPO4 only reduces the luminescence lifetime by ≈50% in heavily doped samples. Various theoretical models are applied to simulate the luminescence decays of Tb3+ and Tb3+, Eu3+‐doped LaPO4 samples of various concentrations and the transfer mechanism is identified as forced electric dipole at each ion.
Constructing Metal Arch Nanobridges Utilizing a Photothermal‐Induced Nanobonding Technique
Authors: Ghosh Pintu , Lu Jinsheng , Luo Hao , Wang Wei , Xu Ziquan , Qiu Min , Li Qiang 
Published: April 2019

AbstractConstruction of multilayered arch nanobridges and nanocantilever structures consisting of silver nanowires using a photothermal‐induced nanobonding technique is demonstrated. The fabricated nanobridges are of different height (300 nm to 20 µm) and span (25–70 µm). Their current–voltage characteristic curves indicate superior electrical connection between the metal nanowires and the abutments (gold thin film). Moreover, super mechanical strength of these arch nanobridges and nanocantilevers is demonstrated by putting gold nanoplates (a few tens of nm thick, a few tens of µm in diameter, and a maximum weight of 3 pN—about 20 times heavier than the silver nanowire of same length) on top of these nanostructures. The multilayered arch nanobridges demonstrate their potential applicability as short‐circuit‐free multipronged electronic connections in nanoelectronic devices. Furthermore, by recording the change in vibration frequency due to proximity of foreign contamination, these nanobridges and the nanocantilevers can be utilized to identify them; that is, these nanostructures can be used as biological sensors to detect viruses, bacteria, and other pathogens.
The Thermoelectric Properties of Bismuth Telluride
Authors: Witting Ian T. , Chasapis Thomas C. , Ricci Francesco , Peters Matthew , Heinz Nicholas A. , Hautier Geoffroy , Snyder G. Jeffrey 
Published: April 2019

AbstractBismuth telluride is the working material for most Peltier cooling devices and thermoelectric generators. This is because Bi2Te3 (or more precisely its alloys with Sb2Te3 for p‐type and Bi2Se3 for n‐type material) has the highest thermoelectric figure of merit, zT, of any material around room temperature. Since thermoelectric technology will be greatly enhanced by improving Bi2Te3 or finding a superior material, this review aims to identify and quantify the key material properties that make Bi2Te3 such a good thermoelectric. The large zT can be traced to the high band degeneracy, low effective mass, high carrier mobility, and relatively low lattice thermal conductivity, which all contribute to its remarkably high thermoelectric quality factor. Using literature data augmented with newer results, these material parameters are quantified, giving clear insight into the tailoring of the electronic band structure of Bi2Te3 by alloying, or reducing thermal conductivity by nanostructuring. For example, this analysis clearly shows that the minority carrier excitation across the small bandgap significantly limits the thermoelectric performance of Bi2Te3, even at room temperature, showing that larger bandgap alloys are needed for higher temperature operation. Such effective material parameters can also be used for benchmarking future improvements in Bi2Te3 or new replacement materials.
Ankle brachial index (ABI) in a cohort of older women in the Philippines: Prevalence of peripheral artery disease and predictors of ABI
Authors: Kuzawa Christopher W. , Barrett Tyler M. , Borja Judith B. , Lee Nanette R. , Aquino Celine T. , Adair Linda S. , McDade Thomas W. 
Published: April 2019

AbstractObjectiveCardiovascular disease (CVD) is rising in low and middle‐income countries, but studies of CVD epidemiology in such settings often focus on risk factors rather than measures of disease progression. Here we use the ankle brachial index (ABI) to assess the prevalence of peripheral artery disease (PAD) among older women living in Metropolitan Cebu, Philippines, and relationships between ABI and CVD risk factors and body composition.MethodsABI was measured using the Doppler technique in 538 female participants in the 2015 Cebu Longitudinal Health and Nutrition Survey (mean age 58 years, range 47‐78 years). ABI was related to a panel of CVD risk factors measured in 2005 and 2012, and to 2012 body composition measures.ResultsThe prevalence of PAD (1.8%) was among the lowest reported in any comparably‐aged sample, and only 9.9% of participants had an ABI indicating borderline PAD risk. Smoking (P < 0.011) and use of CVD medications (P < 0.0001) predicted lower ABI (indicating higher PAD risk), which was also lower in relation to 2012 systolic blood pressure (P < 0.054). ABI was unrelated to other CVD risk factors. An apparent protective relationship between body mass index (BMI) and ABI, noted in previous studies, was found to be confounded by protective relationships between ABI and fat free mass, height, and grip strength (all P < 0.05).ConclusionsThe prevalence of PAD is low in Cebu Longitudinal Health and Nutrition Survey participants, and ABI was related to few CVD risk factors. Past reports of lower PAD risk in relation to BMI may reflect confounding by lean mass, which has protective relationships with ABI.