bluuebunny/crossref_metadata_2025_split huggingface dataset:
Illumination‐Induced Halide Segregation in Gradient Bandgap Mixed‐Halide Perovskite Nanoplatelets
Authors: Zhou Chunhua , Ou Qingdong , Chen Weijian , Gan Zhixing , Wang James , Bao Qiaoliang , Wen Xiaoming , Jia Baohua 
Published: October 2018

AbstractEfficient energy funneling has exhibited great contribution to the high performance of perovskite‐based optoelectronic devices. Here, formamidinium (FA+, HC(NH2)2+) lead mixed‐halide nanoplatelets (FAPb(BrxI1−x)3) with gradient bandgap are fabricated using chemical vapor deposition followed with bromide–iodide substitution by exposure to FABr vapor. The as‐fabricated perovskite nanoplatelets exhibit pure bromide phase in the thin nanoplatelet (tens of nanometers) and a gradual bromide–iodide composite, thus with gradient bandgap (2.29–1.56 eV), in the thick nanoplatelet (more than hundreds of nanometers). Accordingly, photoluminescence (PL) spectra are observed at 540, 560/610, and 735/790 nm, respectively. In such gradient bandgap structures, photogenerated carriers can effectively transfer and emit in the low‐bandgap region by energy funneling. With illumination, the PL spectrum of Br‐rich phase exhibits blueshift and therefore 610 nm band disappears. In contrast, redshift is observed in I‐rich phase due to the decrease of 735 nm band while an increase of 790 nm band. It is demonstrated that irreversible and stable phases are formed with illumination in both Br‐rich and I‐rich nanoplatelets. This investigation develops a method to fabricate gradient bandgap perovskites with designed energy funneling, and also provides significant insight into the halide segregation in such special perovskites, which greatly benefits their future optoelectronic applications.
Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using Complementary DFT and Machine Learning Approaches
Authors: Tawfik Sherif Abdulkader , Isayev Olexandr , Stampfl Catherine , Shapter Joe , Winkler David A. , Ford Michael J. 
Published: October 2018

AbstractThere are now, in principle, a limitless number of hybrid van der Waals (vdW) heterostructures that can be built from the rapidly growing number of 2D layers. The key question is how to explore this vast parameter space in a practical way. Computational methods can guide experimental work. However, even the most efficient electronic structure methods such as density functional theory, are too time consuming to explore more than a tiny fraction of all possible hybrid 2D materials. A combination of density functional theory (DFT) and machine learning techniques provide a practical method for exploring this parameter space much more efficiently than by DFT or experiments. As a proof of concept, this methodology is applied to predict the interlayer distance and band gap of bilayer heterostructures. The methods quickly and accurately predict these important properties for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of vdW heterostructures to identify new hybrid materials with useful and interesting properties.
The Recent Advance in Fiber‐Shaped Energy Storage Devices
Authors: Liao Meng , Ye Lei , Zhang Ye , Chen Taiqiang , Peng Huisheng 
Published: October 2018

AbstractWearable electronic devices that can be directly worn on the human body or combined with daily textiles have experienced a booming development with the rapid development of mobile electronics. These wearable electronic devices strongly demand indispensable, high performance power systems with small size, high flexibility, and adaptability to comfort frequent deformations during usage. Fabricating high‐performance energy storage systems in a 1D shape like fiber is recognized as a promising strategy to address the above issues. These fiber‐shaped power systems with diameters from tens to hundreds of micrometers can adapt to various deformations for stable operation in close contact with the human body. It is also possible to further weave such 1D energy storage devices into breathable textiles with matching electrochemical performances for the wearable electronics. Here, the key advancements related to fiber‐shaped energy storage devices are reviewed, including the synthesis of materials, the design of structures, and the optimization of properties for the most explored energy storage devices, i.e., supercapacitors, aprotic lithium‐based batteries, as well as novel aqueous battery systems. The remaining challenges are finally discussed to highlight the future direction of the development of fiber‐shaped energy storage devices.
Thermally Enhanced n‐Type Thermoelectric Behavior in Completely Organic Graphene Oxide‐Based Thin Films
Authors: Cho Chungyeon , Bittner Noah , Choi Woongchul , Hsu Jui‐Hung , Yu Choongho , Grunlan Jaime C. 
Published: October 2018

AbstractAir‐stable n‐type organic thermoelectric (TE) materials with high power factor are needed to produce efficient, lightweight devices that could be self‐powered by harnessing waste heat. Here, a completely organic n‐type TE nanocomposite is achieved by depositing layers of double‐walled carbon nanotubes (DWNT) stabilized with polyethylenimine (PEI) and graphene oxide (GO) in a layer‐by‐layer fashion from aqueous solutions. A 30 bilayer (BL) film (≈610 nm thick), comprised of this DWNT‐PEI/GO sequence, exhibits electrical conductivity of 27.3 S cm−1 and a Seebeck coefficient of −30 µV K−1, producing a power factor of 2.5 µW m−1 K−2. Low temperature thermal reduction (150 °C for 30 min) of this composite thin film significantly improves its thermoelectric performance. An electrical conductivity of 460 S cm−1 and Seebeck coefficient of −93 µV K−1 are achieved. A 30 BL DWNT‐PEI/reduced graphene oxide (rGO) film (≈480 nm thick) exhibits a power factor as large as 400 µW m−1 K−2, which is one of the highest values reported for an organic n‐type material. By depositing layers containing montmorillonite clay on top, these n‐type nanocomposites exhibit excellent air stability. This combination of air stability and high power factor could enable efficient thermoelectric devices on flexible substrates (e.g., clothing).
Patterning Vertically Grown Gold Nanowire Electrodes for Intrinsically Stretchable Organic Transistors
Authors: Zhu Bowen , Gong Shu , Lin Fenge , Wang Yan , Ling Yunzhi , An Tiance , Cheng Wenlong 
Published: October 2018

AbstractAdvances in large‐area organic electronics for sensor arrays and electronic skins demand highly stretchable, patternable, and conformal electrodes to minimize contact resistance when sensing devices are mechanically deformed. Gold is an excellent electrode material with work function matching well with p‐type organic transistors. However, it is non‐trivial to fabricate highly stretchable gold electrodes for stretchable organic electronics. Here, by combining the advantages of both top‐down patterning and bottom‐up synthesis, a new materials platform of patterned vertically grown gold nanowires (AuNWs) for constructing intrinsically stretchable electrodes, with high conductivity of 1288 S cm−1 at 0% and 152 S cm−1 at 170% strain, is introduced. Such patterned vertical AuNWs can be embedded in an elastomer matrix, leading to stretchable electrodes that are mechanically robust and durable. The interface between AuNWs electrodes and poly(3‐hexylthiophene) thin film shows ohmic contact for the entire strain regime from 0% to 100%, indicating low contact resistance. A stretchable organic transistor with ion gel as the dielectric is demonstrated, which can survive up to 100% strain without much performance degradation. The results indicate that our methodology may be extended to other organic semiconducting materials, hence, offering a general electrode materials platform for devising high performance intrinsically stretchable organic transistors.
Surface Doping to Enhance Structural Integrity and Performance of Li‐Rich Layered Oxide
Authors: Liu Shuai , Liu Zepeng , Shen Xi , Li Weihan , Gao Yurui , Banis Mohammad Norouzi , Li Minsi , Chen Kai , Zhu Liang , Yu Richeng , Wang Zhaoxiang , Sun Xueliang , Lu Gang , Kong Qingyu , Bai Xuedong , Chen Liquan 
Published: October 2018

AbstractThe Li‐rich layer‐structured oxides are regarded as one of the most promising cathode materials for their high energy density but suffer from severe problems such as capacity fading, poor rate performance, and continuous potential dropping. These issues are addressed here by surface doping of niobium (Nb) and other heavy ions in a Li‐rich Mn‐based layered oxide, Li1.2Mn0.54Ni0.13Co0.13O2. The doped ions are verified to be located in the Li‐layer near the oxide surface; they bind the slabs via the strong NbO bonds and “inactivate” the surface oxygen, enhancing the structural stability. The specific capacity of the modified oxide reaches 320 mAh g−1 in the initial cycle, 94.5% of which remains after 100 cycles. More importantly, the average discharge potential drops only by 136 mV in this process. The findings of this study illustrate the importance of inactivating the surface oxygen in suppressing the cation mixing in the bulk, providing an effective strategy for designing high‐performance Li‐rich cathode materials.
Surface Passivation and Carrier Collection in {110}, {100} and Circular Si Microwire Solar Cells
Authors: Ro Yun Goo , Chen Renjie , Liu Ren , Li Nan , Williamson Theodore , Yoo Jinkyoung , Sim Sangwan , Prasankumar Rohit P. , Dayeh Shadi A. 
Published: October 2018

AbstractSurface recombination is a major bottleneck for realizing highly efficient micro/nanostructure solar cells. Here, parametric studies of the influence of Si microwire (SiMW) surface‐facet orientation (rectangular with flat‐facets, {110}, {100} and circular), with a fixed height of 10 µm, diameter (D = 1.5–9.5 µm), and sidewall spacing (S = 2.5–8.5 µm), and mesh‐grid density (1–16 mm−2) on recombination and carrier collection in SiMW solar cells with radial p‐n junctions are reported. An effective surface passivation layer composed of thin thermally grown silicon dioxide (SiO2) and silicon nitride (SiNx) layers is employed. For a fixed D of 1.5 µm, tight SiMW spacing results in improved short‐circuit current density (Jsc = 30.1 mA cm−2) and sparse arrays result in open‐circuit voltages (Voc = 0.552 V) that are similar to those of control Si planar cells. For a fixed S, smaller D results in better light trapping at shorter wavelengths and higher Jsc while larger D exhibits better light trapping at larger wavelengths and a higher Voc. With a mesh‐grid electrode the power conversion efficiency increases to 15.3%. These results provide insights on the recombination mechanisms in SiMW solar cells and provide general design principles for optimizing their performance.
Understanding the Exceptional Performance of Lithium‐Ion Battery Cathodes in Aqueous Electrolytes at Subzero Temperatures
Authors: Ramanujapuram Anirudh , Yushin Gleb 
Published: October 2018

AbstractLithium‐ion batteries with aqueous electrolytes can be excellent candidates for battery applications at low temperatures. In contrast to a common misconception, aqueous lithium ion batteries can operate at several tens of degrees below the freezing point of water when high concentration electrolyte solutions are utilized. Furthermore, it is reported here that the performance of intercalation cathodes in aqueous electrolytes is quite remarkable and superior to that in common organic electrolytes at very low temperatures down to about −40 °C. Here in the performance of water‐based electrolyte solutions‐based on three low‐cost inorganic salts (LiNO3, Li2SO4, and LiCl) and that of the corresponding aqueous battery systems is studied in order to understand the rate‐limiting step at sub‐zero temperatures. It is found that the charge transfer resistance is the largest impedance contributor at low temperatures. However, layered cathodes in aqueous electrolytes do not exhibit a significant increase in the charge‐transfer resistance, or a reduction in the accessible capacity during charging until the temperature is close to the solution freezing point. This is in sharp contrast to their behavior in organic electrolytes that do not support any performance below −20 °C. This different behavior explains the dramatically superior performance of lithium ion battery cathodes in water‐based electrolytes at lower temperatures.
K‐Birnessite Electrode Obtained by Ion Exchange for Potassium‐Ion Batteries: Insight into the Concerted Ionic Diffusion and K Storage Mechanism
Authors: Gao Ang , Li Min , Guo Nannan , Qiu Daping , Li Yan , Wang Senhao , Lu Xia , Wang Feng , Yang Ru 
Published: October 2018

AbstractNovel and low‐cost rechargeable batteries are of considerable interest for application in large‐scale energy storage systems. In this context, K‐Birnessite is synthesized using a facile solid‐state reaction as a promising cathode for potassium‐ion batteries. During synthesis, an ion exchange protocol is applied to increase K content in the K‐Birnessite electrode, which results in a reversible capacity as high as 125 mAh g−1 at 0.2 C. Upon K+ exchange the reversible phase transitions are verified by in situ X‐ray diffraction (XRD) characterization. The underlying mechanism is further revealed to be the concerted K+ ion diffusion with quite low activation energies by first‐principle simulations. These new findings provide new insights into electrode process kinetics, and lay a solid foundation for material design and optimization of potassium‐ion batteries for large‐scale energy storage.
Evolution of leaf structure and drought tolerance in species of Californian Ceanothus
Authors: Fletcher Leila R. , Cui Hongxia , Callahan Hilary , Scoffoni Christine , John Grace P. , Bartlett Megan K. , Burge Dylan O. , Sack Lawren 
Published: October 2018

Premise of the StudyStudies across diverse species have established theory for the contribution of leaf traits to plant drought tolerance. For example, species in more arid climates tend to have smaller leaves of higher vein density, higher leaf mass per area, and more negative osmotic potential at turgor loss point (πTLP). However, few studies have tested these associations for species within a given lineage that have diversified across an aridity gradient.MethodsWe analyzed the anatomy and physiology of 10 Ceanothus (Rhamnaceae) species grown in a common garden for variation between and within “wet” and “dry” subgenera (Ceanothus and Cerastes, respectively) and analyzed a database for 35 species for leaf size and leaf mass per area (LMA). We used a phylogenetic generalized least squares approach to test hypothesized relationships among traits, and of traits with climatic aridity in the native range. We also tested for allometric relationships among anatomical traits.Key ResultsLeaf form, anatomy, and drought tolerance varied strongly among species within and between subgenera. Cerastes species had specialized anatomy including hypodermis and encrypted stomata that may confer superior water storage and retention. The osmotic potentials at turgor loss point (πTLP) and full turgor (πo) showed evolutionary correlations with the aridity index (AI) and precipitation of the 10 species’ native distributions, and LMA with potential evapotranspiration for the 35 species in the larger database. We found an allometric correlation between upper and lower epidermal cell wall thicknesses, but other anatomical traits diversified independently.ConclusionsLeaf traits and drought tolerance evolved within and across lineages of Ceanothus consistently with climatic distributions. The πTLP has signal to indicate the evolution of drought tolerance within small clades.
Rates of human–macaque interactions affect grooming behavior among urban‐dwelling rhesus macaques (Macaca mulatta)
Authors: Kaburu Stefano S. K. , Marty Pascal R. , Beisner Brianne , Balasubramaniam Krishna N. , Bliss‐Moreau Eliza , Kaur Kawaljit , Mohan Lalit , McCowan Brenda 
Published: October 2018

AbstractObjectivesThe impact of anthropogenic environmental changes may impose strong pressures on the behavioral flexibility of free‐ranging animals. Here, we examine whether rates of interactions with humans had both a direct and indirect influence on the duration and distribution of social grooming in commensal rhesus macaques (Macaca mulatta).Materials and MethodsData were collected in two locations in the city of Shimla in northern India: an urban setting and a temple area. We divided these two locations in a series of similar‐sized physical blocks (N = 48) with varying rates of human–macaque interactions. We conducted focal observations on three free‐ranging rhesus macaque groups, one in the urban area and two in the temple area.ResultsOur analysis shows that macaques engaged in shorter grooming bouts and were more vigilant while grooming in focal sessions during which they interacted with people more frequently, suggesting that humans directly affected grooming effort and vigilance behavior. Furthermore, we found that in blocks characterized by higher rates of human–macaque interactions grooming bouts were shorter, more frequently interrupted by vigilance behavior, and were less frequently reciprocated.DiscussionOur work shows that the rates of human–macaque interaction had both a direct and indirect impact on grooming behavior and that macaques flexibly modified their grooming interactions in relation to the rates of human–macaque interaction to which they were exposed. Because grooming has important social and hygienic functions in nonhuman primates, our work suggests that human presence can have important implications for animal health, social relationships and, ultimately, fitness. Our results point to the need of areas away from people even for highly adaptable species where they can engage in social interactions without human disruption.
From Laboratory Press to Spins with Giant Effects
Authors: Weihrich Richard , Pöttgen Rainer , Pielnhofer Florian 
Published: October 2018

AbstractParallelly aligned spins in Co‐Kagome nets have provided several reasons for researchers to celebrate: Liu et al. and Wang et al. have reported discoveries of unique combinations of properties: Sn2Co3S2=Co3Sn2S2=SnCo3/2S exhibits giant anomalous Hall effects that exceed those of known materials by orders of magnitude. For this laboratory curiosity, a specific electronic topology has been discovered in the predicted half‐metal ferromagnetic S=
state that makes it a fascinating example of the novel group of magnetic Weyl semimetals. We present a chemical view on this compound that was little understood for a long time, but that is now also studied with respect to skyrmion lattices and thermoelectrics.
Facilitating a high‐performance photocatalyst for Suzuki reaction: Palladium nanoparticles immobilized on reduced graphene oxide‐doped graphitic carbon nitride
Authors: Zhao Xiaohua , Xie Jiateng , Liu Xin , Liu Xiang 
Published: October 2018

We prepared a non‐covalently coupled hybrid of reduced graphene oxide (rGO)‐doped graphitic carbon nitride (g‐C3N4) by freezing‐assisted assembly and calcination. Fourier transform infrared, Raman and X‐ray photoelectron spectroscopies and transmission electron microscopy confirmed that rGO was incorporated into the bulk g‐C3N4, which was an ideal support for loading Pd nanoparticles. The Pd nanoparticles with an average size of 4.57 nm were uniformly dispersed on the rGO‐doped g‐C3N4 surface. The layered structure provided large contact area of g‐C3N4 with rGO, further accelerating the electron transfer rate and inhibiting electron–hole recombination. Consequently, compared with Pd/rGO/g‐C3N4 and Pd/g‐C3N4, the Pd/rGO‐doped g‐C3N4 showed a prominent catalytic activity for visible‐light‐driven photocatalytic Suzuki–Miyaura coupling at ambient temperature. The Pd/rGO‐doped g‐C3N4 exhibited very high stability after six consecutive cycles with minimal loss of catalytic activity.
Monodentate aminophosphine nickel(II)‐ and palladium(II)‐catalyzed ethylene oligomerization and norbornene polymerization
Authors: Rong Chunyong , Li Weimin , Tan Chen 
Published: October 2018

Nickel(II) and palladium(II) complexes of monodentate aminophosphine ligands were prepared and characterized. In ethylene oligomerization and subsequent Friedel–Crafts alkylation of toluene, the Ni(II) complexes Ni‐1 and Ni‐2 were activated with aluminium co‐catalysts and generated tandem catalysts with high activities (up to 1.1 × 106 g (mol Ni)−1 h−1) which are comparable with those of previously reported bidentate Ni(II) catalysts. The Pd(II) precatalyst Pd‐1 showed high activities (up to 2.0 × 105 g (mol Pd)−1 h−1) in the polymerization of norbornene.
Biomechanical Study of the Development of Long Bones: Finite Element Structure Synthesis of the Human Second Proximal Phalanx Under Growth Conditions
Authors: Lipphaus Andreas , Witzel Ulrich 
Published: October 2018

ABSTRACTTorsional loads are a possible mechanical explanation for the architecture of long bone. Finite element structure synthesis (FESS) has previously successfully been used as a deductive technique using Wolff's Law by applying expected loads to an unspecific homogeneous solid and eliminating stress free parts to verify muscle forces. The extended approach presented in this article includes further mechanobiological rules to model the development from a cartilage model to a finger bone. In contrast to former computational models, simulation of processes leading to both external growth and internal differentiation are included. Combined axial and torsional loads synthesize a complete human secondary proximal phalanx model comparable to form and internal structure to that observedin vivo. While the computational model is very sensitive to initial alterations of loads, changes after growth have a minor effect as observed in animal models. Predictions of cartilage growth and ossification during FESS showed significant similarities to ontogeny indicating the importance of mechanical factors for the morphogenesis of bone during growth. Anat Rec, 302:1389–1398, 2019. © 2018 Wiley Periodicals, Inc.
Targeted Inhibition of Aggrecanases Prevents Articular Cartilage Degradation and Augments Bone Mass in the STR/Ort Mouse Model of Spontaneous Osteoarthritis
Authors: Kanakis Ioannis , Liu Ke , Poulet Blandine , Javaheri Behzad , van ’t Hof Rob J. , Pitsillides Andrew A. , Bou‐Gharios George 
Published: October 2018

ObjectiveCartilage destruction in osteoarthritis (OA) is mediated mainly by matrix metalloproteinases (MMPs) and ADAMTS. The therapeutic candidature of targeting aggrecanases has not yet been defined in joints in which spontaneous OA arises from genetic susceptibility, as in the case of the STR/Ort mouse, without a traumatic or load‐induced etiology. In addition, we do not know the long‐term effect of aggrecanase inhibition on bone. We undertook this study to assess the potential aggrecanase selectivity of a variant of tissue inhibitor of metalloproteinases 3 (TIMP‐3), called [‐1A]TIMP‐3, on spontaneous OA development and bone formation in STR/Ort mice.MethodsUsing the background of STR/Ort mice, which develop spontaneous OA, we generated transgenic mice that overexpress [‐1A]TIMP‐3, either ubiquitously or conditionally in chondrocytes. [‐1A]TIMP‐3 has an extra alanine at the N‐terminus that selectively inhibits ADAMTS but not MMPs. We analyzed a range of OA‐related measures in all mice at age 40 weeks.ResultsMice expressing high levels of [‐1A]TIMP‐3 were protected against development of OA, while those expressing low levels were not. Interestingly, we also found that high levels of [‐1A]TIMP‐3 transgene overexpression resulted in increased bone mass, particularly in females. This regulation of bone mass was at least partly direct, as adult mouse primary osteoblasts infected with [‐1A]TIMP‐3 in vitro showed elevated rates of mineralization.ConclusionThe results provide evidence that [‐1A]TIMP‐3–mediated inhibition of aggrecanases can protect against cartilage degradation in a naturally occurring mouse model of OA, and they highlight a novel role that aggrecanase inhibition may play in increased bone mass.