bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bioinspired Artificial Eyes: Optic Components, Digital Cameras, and Visual Prostheses
Authors: Lee Gil Ju , Choi Changsoon , Kim Dae‐Hyeong , Song Young Min 
Published: December 2017

AbstractThe diverse vision systems found in nature can provide interesting design inspiration for imaging devices, ranging from optical subcomponents to digital cameras and visual prostheses, with more desirable optical characteristics compared to conventional imagers. The advantages of natural vision systems include high visual acuity, wide field of view, wavelength‐free imaging, improved aberration correction and depth of field, and high motion sensitivity. Recent advances in soft materials, ultrathin electronics, and deformable optoelectronics have facilitated the realization of novel processes and device designs that mimic biological vision systems. This review highlights recent progress and continued efforts in the research and development of bioinspired artificial eyes. At first, the configuration of two representative eyes found in nature: a single‐chambered eye and a compound eye, is explained. Then, advances in bioinspired optic components and image sensors are discussed in terms of materials, optical/mechanical designs, and integration schemes. Subsequently, novel visual prostheses as representative application examples of bioinspired artificial eyes are described.
Room‐Temperature Nonvolatile Memory Based on a Single‐Phase Multiferroic Hexaferrite
Authors: Zhai Kun , Shang Da‐Shan , Chai Yi‐Sheng , Li Gang , Cai Jian‐Wang , Shen Bao‐Gen , Sun Young 
Published: December 2017

AbstractThe cross‐coupling between electric polarization and magnetization in multiferroic materials provides a great potential for creating next‐generation memory devices. Current studies on magnetoelectric (ME) applications mainly focus on ferromagnetic/ferroelectric heterostructures because single‐phase multiferroics with strong magnetoelectric coupling at room temperature are still very rare. Here a type of nonvolatile memory device is presented solely based on a single‐phase multiferroic hexaferrite Sr3Co2Fe24O41 which exhibits nonlinear magnetoelectric effects at room temperature. The principle is to store binary information by employing the states (magnitude and sign) of the first‐order and the second‐order magnetoelectric coefficients (α and β), instead of using magnetization, electric polarization, and resistance. The experiments demonstrate repeatable nonvolatile switch of α and β by applying pulsed electric fields at room temperature, respectively. Such kind of memory device using single‐phase multiferroics paves a pathway toward practical applications of spin‐driven multiferroics.
Passivated Perovskite Crystallization via g‐C3N4 for High‐Performance Solar Cells
Authors: Jiang Lu‐Lu , Wang Zhao‐Kui , Li Meng , Zhang Cong‐Cong , Ye Qing‐Qing , Hu Ke‐Hao , Lu Ding‐Ze , Fang Peng‐Fei , Liao Liang‐Sheng 
Published: December 2017

AbstractOrganometallic halide perovskite films with good surface morphology and large grain size are desirable for obtaining high‐performance photovoltaic devices. However, defects and related trap sites are generated inevitably at grain boundaries and on surfaces of solution‐processed polycrystalline perovskite films. Seeking facial and efficient methods to passivate the perovskite film for minimizing defect density is necessary for further improving the photovoltaic performance. Here, a convenient strategy is developed to improve perovskite crystallization by incorporating a 2D polymeric material of graphitic carbon nitride (g‐C3N4) into the perovskite layer. The addition of g‐C3N4 results in improved crystalline quality of perovskite film with large grain size by retarding the crystallization rate, and reduced intrinsic defect density by passivating charge recombination centers around the grain boundaries. In addition, g‐C3N4 doping increases the film conductivity of perovskite layer, which is beneficial for charge transport in perovskite light‐absorption layer. Consequently, a champion device with a maximum power conversion efficiency of 19.49% is approached owing to a remarkable improvement in fill factor from 0.65 to 0.74. This finding demonstrates a simple method to passivate the perovskite film by controlling the crystallization and reducing the defect density.
Engineering of Self‐Propelling Microbots and Microdevices Powered by Magnetic and Electric Fields
Authors: Han Koohee , Shields C. Wyatt , Velev Orlin D. 
Published: December 2017

AbstractIn the last two decades, advances in micro‐ and nanofabrication have enabled the development of a wide variety of active or “self‐propelling” microparticles, which convert energy from their environment into directed motion. While these autonomous entities have shown promise for efficient locomotion on the microscale, their practical utility remains unrealized due to their inability to perform multiple useful tasks on demand. From an engineering perspective, the active particle behavior can be encoded on an individual level by tailoring key design elements such as shape, polarizability, surface pattern, and bulk functionality. This feature article focusses on active particles powered by electric and magnetic fields, as these sources of energy allow the particles to: (1) move in several phenomenologically unique ways, (2) respond in a reliable manner to the field parameters, and (3) interact synergistically to enable multiple functions. It is hypothesized how future generations of such particles may remotely harvest and transduce energy to perform several useful tasks such as biosensing and delivering drugs. As a step toward realizing such particles, several new types of active particles are demonstrated. Finally, a perspective on the future directions of this emerging field is provided by discussing current challenges, potential applications as well as future opportunities.
Electron Field Emission of Geometrically Modulated Monolayer Semiconductors
Authors: Yang Tung‐Han , Chiu Kuan‐Chang , Harn Yeu‐Wei , Chen Han‐Yi , Cai Ren‐Fong , Shyue Jing‐Jong , Lo Shen‐Chuan , Wu Jenn‐Ming , Lee Yi‐Hsien 
Published: December 2017

AbstractElectron field emission, electrons emitted from solid surfaces under high electric field, offers significant scientific interests in materials sciences and potential optoelectronics applications. 2D atomic layers, such as MoS2, exhibit fascinating properties for diverse applications in next‐generation nanodevices and rich physical phenomena for fundamental research. However, the study on field emission of semiconducting monolayers is lacking owing to its low efficiency and stability of electron emission. Here, electron field emission of the geometrically modulated monolayer semiconductors suspended with 1D nanoarrays is demonstrated. Chemical vapor deposition synthesis of two prototype monolayers of transition metal dichalcogenides (TMD), MoS2 and MoSe2, is presented and their diverse band structures offer an ideal platform to explore the fundamental process of the electron emission in the TMD. Geometrical modulation and charge transfer of the semiconducting monolayers can be significantly tuned with the structural suspension with the 1D ZnO nanoarrays. Possible mechanisms on the enhanced electron emission of the 2D monolayers are discussed. With geometrical control of the monolayers, a highly efficient and stable electron emission of TMD monolayers is achieved in low turn‐on electric fields, enabling applications on electrons sources and opening a new avenue toward geometrically tuned atomic layers.
A Mechanoresponsive Phase‐Changing Electrolyte Enables Fabrication of High‐Output Solid‐State Photobioelectrochemical Devices from Pigment‐Protein Multilayers
Authors: Ravi Sai Kishore , Swainsbury David J. K. , Singh Varun Kumar , Ngeow Yoke Keng , Jones Michael R. , Tan Swee Ching 
Published: December 2017

AbstractExploitation of natural photovoltaic reaction center pigment proteins in biohybrid architectures for solar energy harvesting is attractive due to their global abundance, environmental compatibility, and near‐unity quantum efficiencies. However, it is challenging to achieve high photocurrents in a device setup due to limitations imposed by low light absorbance by protein monolayers and/or slow long‐range diffusion of liquid‐phase charge carriers. In an attempt to enhance the photocurrent density achievable by pigment proteins, here, an alternative solid‐state device architecture enabled by a mechanoresponsive gel electrolyte that can be applied under nondenaturing conditions is demonstrated. The phase‐changing electrolyte gel provides a pervading biocompatible interface for charge conduction through highly absorbing protein multilayers that are fabricated in a simple fashion. Assembled devices exhibit enhanced current stability and a maximal photoresponse of ≈860 µA cm−2, a fivefold improvement over the best previous comparable devices under standard illumination conditions. Photocurrent generation is enhanced by directional energy transfer through extended layers of light‐harvesting complexes, mimicking the modular antenna/transducer architecture of natural photosystems, and by metastable radical pair formation when photovoltaic reaction centers are embedded throughout light‐harvesting regions of the device.
Artificial Muscles: Mechanisms, Applications, and Challenges
Authors: Mirvakili Seyed M. , Hunter Ian W. 
Published: December 2017

AbstractThe area of artificial muscle is a highly interdisciplinary field of research that has evolved rapidly in the last 30 years. Recent advances in nanomaterial fabrication and characterization, specifically carbon nanotubes and nanowires, have had major contributions in the development of artificial muscles. However, what can artificial muscles really do for humans? This question is considered here by first examining nature's solutions to this design problem and then discussing the structure, actuation mechanism, applications, and limitations of recently developed artificial muscles, including highly oriented semicrystalline polymer fibers; nanocomposite actuators; twisted nanofiber yarns; thermally activated shape‐memory alloys; ionic‐polymer/metal composites; dielectric‐elastomer actuators; conducting polymers; stimuli‐responsive gels; piezoelectric, electrostrictive, magnetostrictive, and photostrictive actuators; photoexcited actuators; electrostatic actuators; and pneumatic actuators.
The Self‐Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance
Authors: Parker Richard M. , Guidetti Giulia , Williams Cyan A. , Zhao Tianheng , Narkevicius Aurimas , Vignolini Silvia , Frka‐Petesic Bruno 
Published: December 2017

AbstractBy controlling the interaction of biological building blocks at the nanoscale, natural photonic nanostructures have been optimized to produce intense coloration. Inspired by such biological nanostructures, the possibility to design the visual appearance of a material by guiding the hierarchical self‐assembly of its constituent components, ideally using natural materials, is an attractive route for rationally designed, sustainable manufacturing. Within the large variety of biological building blocks, cellulose nanocrystals are one of the most promising biosourced materials, primarily for their abundance, biocompatibility, and ability to readily organize into photonic structures. Here, the mechanisms underlying the formation of iridescent, vividly colored materials from colloidal liquid crystal suspensions of cellulose nanocrystals are reviewed and recent advances in structural control over the hierarchical assembly process are reported as a toolbox for the design of sophisticated optical materials.
Continuous‐Wave Lasing in Cesium Lead Bromide Perovskite Nanowires
Authors: Evans Tyler J. S. , Schlaus Andrew , Fu Yongping , Zhong Xinjue , Atallah Timothy L. , Spencer Michael S. , Brus Louis E. , Jin Song , Zhu X.‐Y. 
Published: December 2017

AbstractLead halide perovskite nanowires (NWs) have been demonstrated in pulsed lasing with high quantum yields, low thresholds, and broad tunability. However, continuous‐wave (CW) lasing, necessary for many optoelectronic applications, has not been achieved to date. This is thought to be due to many‐body screening, which reduces the excitonic resonance enhancement of the oscillator strength at high excitation densities necessary for population inversion. Here CW lasing in CsPbBr3 perovskite NWs is reported. Analysis of the cavity modes and their temperature dependence reveals that both CW and pulsed lasing originate from polariton modes near the bottleneck region on the lower polariton branch, with a vacuum Rabi splitting of 0.20 ± 0.03 eV. These findings suggest that lead halide perovskite NWs may serve as low‐power CW coherent light sources and as model systems for polaritonics in the strong‐coupling regime.
Boosting the Photoluminescence of Monolayer MoS2 on High‐Density Nanodimer Arrays with Sub‐10 nm Gap
Authors: Hao Qi , Pang Jinbo , Zhang Yang , Wang Jiawei , Ma Libo , Schmidt Oliver G. 
Published: December 2017

AbstractPatterned plasmonic nanodimers are fabricated exploiting an ultrathin porous anodic aluminum oxide membrane as a mask during angle‐resolved shadow deposition. The fabricated nanodimer arrays exhibit consistent sub‐10 nm gaps and a high particle density up to 1.0 × 1010 cm−2 over a large area. The ultrasmall dimer gaps provide highly confined electromagnetic fields, which strongly enhance the photoluminescence (PL) emission and Raman scattering from the surrounding monolayer molybdenum disulphide (MoS2). The ensemble PL intensity from MoS2/dimers is enhanced by up to a factor of ≈160 by resonant excitation of the dimer modes. Anisotropic polarization‐dependent characteristics of PL and Raman from the MoS2/dimers confirm that the dominant enhancement originates from the dimer configuration. These experiments demonstrate a facile approach for the fabrication of low‐cost high‐performance 2D material‐based optoelectronic devices.
High Density and Super Ultra‐Microporous‐Activated Carbon Macrospheres with High Volumetric Capacity for CO2 Capture
Authors: Liu Jingjing , Liu Xin , Sun Yuan , Sun Chenggong , Liu Hao , Stevens Lee A. , Li Kaixi , Snape Colin E. 
Published: December 2017

AbstractActivated carbon (AC) spheres with a diameter of 1.0–2.0 mm are synthesized from coal tar pitch for postcombustion carbon capture. The as‐prepared AC macrospheres after potassium hydroxide (KOH) activation are found to possess extraordinarily developed microporosity of which 87% is ultra‐microporosity with pore diameters less than 0.8 nm. Despite the relatively low surface area of just 714 m2 g−1 with a pore volume of 0.285 cm3 g−1, the macrospherical carbon adsorbents achieve exceedingly high CO2 uptake capacities of 3.15 and 1.86 mmol g−1 at 0 and 25 °C, respectively, with a CO2 partial pressure of 0.15 bar. Cyclic lifetime performance testing demonstrates that the CO2 uptake is fully reversible with fast adsorption and desorption kinetics. More importantly, due to their high bulk density of ≈1.0 g cm−3, the AC macrospheres exhibit extremely high volumetric CO2 uptakes of up to 81.8 g L−1 at 25 °C at 0.15 bar CO2, which represents the highest value ever reported for ACs. The high ultra‐microporosity coupled with the potassium‐modified physiochemical surface properties is found to be responsible for the outstanding CO2 adsorption performance of the pitch‐based AC macrospheres.
Improved interfacial properties of carbon fiber composites by building stress transition layer with carbon nanotubes
Authors: Zhang Wenqing , Yang Qing , Deng Xi , Bai Gang , Xiao Wei , Sui Gang , Yang Xiaoping 
Published: December 2017

AbstractFor the purpose of improvement in interfacial property of carbon fiber composites through a facile process, the carboxyl‐functionalized multiwalled carbon nanotubes (MWCNTs‐COOH) were incorporated into the surface of JH‐T800 carbon fiber using sizing and deposition technology. The surface morphology of MWCNTs‐COOH‐modified carbon fibers and fracture surfaces of unidirectional carbon fiber composites were observed via scanning electron microscopy and atomic force microscopy. According to the results of composites fragmentation test, the adoption of MWCNTs‐COOH‐modified carbon fibers resulted in the improved carbon fiber/epoxy matrix interfacial bonding and interlaminer property by 32.1% and 31.9%, respectively. Through the combination of the above two kinds of pretreating process of carbon fibers, a stress transition layer with the gradient distribution of MWCNTs was built between carbon fiber and resin matrix, which was favorable for releasing stress concentration and hindering the propagation of crack, resulting in a higher reinforcing efficiency for the existing carbon fiber composites.
Voltage Losses in Organic Solar Cells: Understanding the Contributions of Intramolecular Vibrations to Nonradiative Recombinations
Authors: Chen Xian‐Kai , Brédas Jean‐Luc 
Published: December 2017

AbstractThe large voltage losses usually encountered in organic solar cells significantly limit the power conversion efficiencies (PCEs) of these devices, with the result that the current highest PCE values in single‐junction organic photovoltaic remain smaller than for other solar cell technologies, such as crystalline silicon or perovskite solar cells. In particular, the nonradiative recombinations to the electronic ground state from the lowest‐energy charge‐transfer (CT) states at the donor–acceptor interfaces in the active layer of organic devices, are responsible for a significant part of the voltage losses. Here, to better comprehend the nonradiative voltage loss mechanisms, a fully quantum‐mechanical rate formula is employed within the framework of time‐dependent perturbation theory, combined with density functional theory. The objective is to uncover the specific contributions of intramolecular vibrations to the CT‐state nonradiative recombinations in several model systems, which include small‐molecule and polymer donors as well as fullerene and nonfullerene acceptors.
Optimized Concentration of Redox Mediator and Surface Protection of Li Metal for Maintenance of High Energy Efficiency in Li–O2 Batteries
Authors: Kwak Won‐Jin , Park Seong‐Jin , Jung Hun‐Gi , Sun Yang‐Kook 
Published: December 2017

AbstractRecently, various approaches for adding redox mediators to electrolytes and introducing protective layers onto Li metal have been suggested to overcome the low energy efficiency and poor cycle life of Li–O2 batteries. However, the catalytic effect of the redox mediator for oxygen evolution gradually deteriorates during repeated cycling owing to its decomposition at the surfaces of both the oxygen electrode (cathode) and the Li metal electrode (anode). Here, optimized Li–O2 batteries are designed with a continuously effective redox mediator and a stable protective layer for the Li metal electrode by optimizing the LiBr concentration and introducing a graphene–polydopamine composite layer, respectively. These synergistic modifications lead to a reduction of the charge potential to below 3.4 V and significantly improve the stability and cycle life of Li–O2 batteries. Consequently, a high energy efficiency of above 80% is maintained over 150 cycles. Herein, it is confirmed that the relationships between all the battery materials should be understood in order to improve the performance of Li–O2 batteries.
Achieving zT > 2 in p‐Type AgSbTe2−xSex Alloys via Exploring the Extra Light Valence Band and Introducing Dense Stacking Faults
Authors: Hong Min , Chen Zhi‐Gang , Yang Lei , Liao Zhi‐Ming , Zou Yi‐Chao , Chen Yan‐Hui , Matsumura Syo , Zou Jin 
Published: December 2017

AbstractThrough simultaneously enhancing the power factor by engineering the extra light band and enhancing phonon scatterings by introducing a high density of stacking faults, a record figure‐of‐merit over 2.0 is achieved in p‐type AgSbTe2−xSex alloys. Density functional theory calculations confirm the presence of the light valence band with large degeneracy in AgSbTe2, and that alloying with Se decreases the energy offset between the light valence band and the valence band maximum. Therefore, a significantly enhanced power factor is realized in p‐type AgSbTe2−xSex alloys. In addition, transmission electron microscopy studies indicate the appearance of stacking faults and grain boundaries, which together with grain boundaries and point defects significantly strengthen phonon scatterings, leading to an ultralow thermal conductivity. The synergetic strategy of simultaneously enhancing power factor and strengthening phonon scattering developed in this study opens up a robust pathway to tailor thermoelectric performance.
A Soft and Robust Spring Based Triboelectric Nanogenerator for Harvesting Arbitrary Directional Vibration Energy and Self‐Powered Vibration Sensing
Authors: Xu Minyi , Wang Peihong , Wang Yi‐Cheng , Zhang Steven L. , Wang Aurelia Chi , Zhang Chunli , Wang Zhengjun , Pan Xinxiang , Wang Zhong Lin 
Published: December 2017

AbstractVibration is a common mechanical phenomenon and possesses mechanical energy in ambient environment, which can serve as a sustainable source of power for equipment and devices if it can be effectively collected. In the present work, a novel soft and robust triboelectric nanogenerator (TENG) made of a silicone rubber‐spring helical structure with nanocomposite‐based elastomeric electrodes is proposed. Such a spring based TENG (S‐TENG) structure operates in the contact‐separation mode upon vibrating and can effectively convert mechanical energy from ambient excitation into electrical energy. The two fundamental vibration modes resulting from the vertical and horizontal excitation are analyzed theoretically, numerically, and experimentally. Under the resonant states of the S‐TENG, its peak power density is found to be 240 and 45 mW m−2 with an external load of 10 MΩ and an acceleration amplitude of 23 m s−2. Additionally, the dependence of the S‐TENG's output signal on the ambient excitation can be used as a prime self‐powered active vibration sensor that can be applied to monitor the acceleration and frequency of the ambient excitation. Therefore, the newly designed S‐TENG has a great potential in harvesting arbitrary directional vibration energy and serving as a self‐powered vibration sensor.
Using Geospatial Research Methods to Examine Resource Accessibility and Availability as it Relates to Community Participation of Individuals with Serious Mental Illnesses
Authors: Townley Greg , Brusilovskiy Eugene , Snethen Gretchen , Salzer Mark S. 
Published: December 2017

AbstractGreater community participation among individuals with serious mental illnesses is associated with better psychosocial and health outcomes. Typically, studies examining community participation have utilized self‐report measures and been conducted in limited settings. The introduction of methodological advances to examining community participation of individuals with serious mental illnesses has the potential to advance the science of community mental health research and invigorate the work of community psychologists in this area. This study employed an innovative geospatial approach to examine the relationship between community participation and resource accessibility (i.e., proximity) and availability (i.e., concentration) among 294 individuals utilizing community mental health services throughout the United States. Findings suggest small but significant associations between community participation and the accessibility and availability of resources needed for participation. Furthermore, findings demonstrate the importance of car access for individuals residing in both urban and non‐urban settings. The methods and results presented in this study have implications for community mental health research and services and provide an illustration of ways that geospatial methodologies can be used to investigate environmental factors that impact community inclusion and participation of individuals with serious mental illnesses.