bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient Triplet–Triplet Annihilation Upconversion in an Electroluminescence Device with a Fluorescent Sensitizer and a Triplet‐Diffusion Singlet‐Blocking Layer
Authors: Chen Chia‐Hsun , Tierce Nathan T. , Leung Man‐kit , Chiu Tien‐Lung , Lin Chi‐Feng , Bardeen Christopher J. , Lee Jiun‐Haw 
Published: October 2018

AbstractSolid‐state triplet–triplet annihilation upconversion (TTAUC) blue emission in an electroluminescence device (i.e., an organic light‐emitting diode (OLED)) is demonstrated. A conventional green fluorophore, tris‐(8‐hydroxyquinoline)aluminum (Alq3), is employed as the sensitizer that generates 75% triplet under electrical pumping for the blue triplet–triplet annihilation emitter, 9,10‐bis(2′‐naphthyl) anthracene (ADN), with the heterojunction bilayer structure. The operation lifetime is elongated both for ADN blue (4.1x) and Alq3 green (34.8%) emission due to efficient use of excitons and separation of recombination and emission zone. To reduce the singlet quenching (SQ) of blue TTAUC signal by the Alq3 sensitizer with lower bandgap, 1‐(2,5‐dimethyl‐4‐(1‐pyrenyl)phenyl)pyrene (DMPPP) is inserted between the Alq3 and ADN as a triplet‐diffusion‐and‐singlet‐blocking layer. DMPPP exhibits triplet energy close to Alq3 and higher than ADN, as well as higher singlet energy than both Alq3 and ADN. It allows triplet diffusion from Alq3 to ADN, but blocks the SQ of the blue TTAUC signal by Alq3. 86.1% intrinsic efficiency of TTAUC is demonstrated in this trilayer (Alq3/DMPPP/ADN) OLED.
Atomic‐Scale Observation of Electrochemically Reversible Phase Transformations in SnSe2 Single Crystals
Authors: Kim Sungkyu , Yao Zhenpeng , Lim Jin‐Myoung , Hersam Mark C. , Wolverton Chris , Dravid Vinayak P. , He Kai 
Published: October 2018

Abstract2D materials have shown great promise to advance next‐generation lithium‐ion battery technology. Specifically, tin‐based chalcogenides have attracted widespread attention because lithium insertion can introduce phase transformations via three types of reactions—intercalation, conversion, and alloying—but the corresponding structural changes throughout these processes, and whether they are reversible, are not fully understood. Here, the first real‐time and atomic‐scale observation of reversible phase transformations is reported during the lithiation and delithiation of SnSe2 single crystals, using in situ high‐resolution transmission electron microscopy complemented by first‐principles calculations. Lithiation proceeds sequentially through intercalation, conversion, and alloying reactions (SnSe2 → LixSnSe2 → Li2Se + Sn → Li2Se + Li17Sn4) in a manner that maintains structural and crystallographic integrity, whereas delithiation forms numerous well‐aligned SnSe2 nanodomains via a homogeneous deconversion process, but gradually loses the coherent orientation in subsequent cycling. Furthermore, alloying and dealloying reactions cause dramatic structural reorganization and thereby consequently reduce structural stability and electrochemical cyclability, which implies that deep discharge for Sn chalcogenide electrodes should be avoided. Overall, the findings elucidate atomistic lithiation and delithiation mechanisms in SnSe2 with potential implications for the broader class of 2D metal chalcogenides.
Facile Fabrication of Large‐Area Atomically Thin Membranes by Direct Synthesis of Graphene with Nanoscale Porosity
Authors: Kidambi Piran R. , Nguyen Giang D. , Zhang Sui , Chen Qu , Kong Jing , Warner Jamie , Li An‐Ping , Karnik Rohit 
Published: October 2018

AbstractDirect synthesis of graphene with well‐defined nanoscale pores over large areas can transform the fabrication of nanoporous atomically thin membranes (NATMs) and greatly enhance their potential for practical applications. However, scalable bottom‐up synthesis of continuous sheets of nanoporous graphene that maintain integrity over large areas has not been demonstrated. Here, it is shown that a simple reduction in temperature during chemical vapor deposition (CVD) on Cu induces in‐situ formation of nanoscale defects (≤2–3 nm) in the graphene lattice, enabling direct and scalable synthesis of nanoporous monolayer graphene. By solution‐casting of hierarchically porous polyether sulfone supports on the as‐grown nanoporous CVD graphene, large‐area (>5 cm2) NATMs for dialysis applications are demonstrated. The synthesized NATMs show size‐selective diffusive transport and effective separation of small molecules and salts from a model protein, with ≈2–100× increase in permeance along with selectivity better than or comparable to state‐of‐the‐art commercially available polymeric dialysis membranes. The membranes constitute the largest fully functional NATMs fabricated via bottom‐up nanopore formation, and can be easily scaled up to larger sizes permitted by CVD synthesis. The results highlight synergistic benefits in blending traditional membrane casting with bottom‐up pore creation during graphene CVD for advancing NATMs toward practical applications.
Charge‐Induced Disorder Controls the Thermal Conductivity of Entropy‐Stabilized Oxides
Authors: Braun Jeffrey L. , Rost Christina M. , Lim Mina , Giri Ashutosh , Olson David H. , Kotsonis George N. , Stan Gheorghe , Brenner Donald W. , Maria Jon‐Paul , Hopkins Patrick E. 
Published: October 2018

AbstractManipulating a crystalline material's configurational entropy through the introduction of unique atomic species can produce novel materials with desirable mechanical and electrical properties. From a thermal transport perspective, large differences between elemental properties such as mass and interatomic force can reduce the rate at which phonons carry heat and thus reduce the thermal conductivity. Recent advances in materials synthesis are enabling the fabrication of entropy‐stabilized ceramics, opening the door for understanding the implications of extreme disorder on thermal transport. Measuring the structural, mechanical, and thermal properties of single‐crystal entropy‐stabilized oxides, it is shown that local ionic charge disorder can effectively reduce thermal conductivity without compromising mechanical stiffness. These materials demonstrate similar thermal conductivities to their amorphous counterparts, in agreement with the theoretical minimum limit, resulting in this class of material possessing the highest ratio of elastic modulus to thermal conductivity of any isotropic crystal.
Self‐Assembly of Large‐Area 2D Polycrystalline Transition Metal Carbides for Hydrogen Electrocatalysis
Authors: Zang Xining , Chen Wenshu , Zou Xiaolong , Hohman J. Nathan , Yang Lujie , Li Buxuan , Wei Minsong , Zhu Chenhui , Liang Jiaming , Sanghadasa Mohan , Gu Jiajun , Lin Liwei 
Published: October 2018

AbstractLow‐dimensional (0/1/2 dimension) transition metal carbides (TMCs) possess intriguing electrical, mechanical, and electrochemical properties, and they serve as convenient supports for transition metal catalysts. Large‐area single‐crystalline 2D TMC sheets are generally prepared by exfoliating MXene sheets from MAX phases. Here, a versatile bottom‐up method is reported for preparing ultrathin TMC sheets (≈10 nm in thickness and >100 μm in lateral size) with metal nanoparticle decoration. A gelatin hydrogel is employed as a scaffold to coordinate metal ions (Mo5+, W6+, Co2+), resulting in ultrathin‐film morphologies of diverse TMC sheets. Carbonization of the scaffold at 600 °C presents a facile route to the corresponding MoCx, WCx, CoCx, and to metal‐rich hybrids (Mo2−xWxC and W/Mo2C–Co). Among these materials, the Mo2C–Co hybrid provides excellent hydrogen evolution reaction (HER) efficiency (Tafel slope of 39 mV dec−1 and 48 mVj = 10 mA cm‐2 in overpotential in 0.5 m H2SO4). Such performance makes Mo2C–Co a viable noble‐metal‐free catalyst for the HER, and is competitive with the standard platinum on carbon support. This template‐assisted, self‐assembling, scalable, and low‐cost manufacturing process presents a new tactic to construct low‐dimensional TMCs with applications in various clean‐energy‐related fields.
Dendrimer‐Based Lipid Nanoparticles Deliver Therapeutic FAH mRNA to Normalize Liver Function and Extend Survival in a Mouse Model of Hepatorenal Tyrosinemia Type I
Authors: Cheng Qiang , Wei Tuo , Jia Yuemeng , Farbiak Lukas , Zhou Kejin , Zhang Shuyuan , Wei Yonglong , Zhu Hao , Siegwart Daniel J. 
Published: October 2018

AbstractmRNA‐mediated protein replacement represents a promising concept for the treatment of liver disorders. Children born with fumarylacetoacetate hydrolase (FAH) mutations suffer from Hepatorenal Tyrosinemia Type 1 (HT‐1) resulting in renal dysfunction, liver failure, neurological impairments, and cancer. Protein replacement therapy using FAH mRNA offers tremendous potential to cure HT‐1, but is currently hindered by the development of effective mRNA carriers that can function in diseased livers. Structure‐guided, rational optimization of 5A2‐SC8 mRNA‐loaded dendrimer lipid nanoparticles (mDLNPs) increases delivery potency of FAH mRNA, resulting in functional FAH protein and sustained normalization of body weight and liver function in FAH−/− knockout mice. Optimization using luciferase mRNA produces DLNP carriers that are efficacious at mRNA doses as low as 0.05 mg kg−1 in vivo. mDLNPs transfect > 44% of all hepatocytes in the liver, yield high FAH protein levels (0.5 mg kg−1 mRNA), and are well tolerated in a knockout mouse model with compromised liver function. Genetically engineered FAH−/− mice treated with FAH mRNA mDLNPs have statistically equivalent levels of TBIL, ALT, and AST compared to wild type C57BL/6 mice and maintain normal weight throughout the month‐long course of treatment. This study provides a framework for the rational optimization of LNPs to improve delivery of mRNA broadly and introduces a specific and viable DLNP carrier with translational potential to treat genetic diseases of the liver.
Current‐Induced Skyrmion Generation through Morphological Thermal Transitions in Chiral Ferromagnetic Heterostructures
Authors: Lemesh Ivan , Litzius Kai , Böttcher Marie , Bassirian Pedram , Kerber Nico , Heinze Daniel , Zázvorka Jakub , Büttner Felix , Caretta Lucas , Mann Maxwell , Weigand Markus , Finizio Simone , Raabe Jörg , Im Mi‐Young , Stoll Hermann , Schütz Gisela , Dupé Bertrand , Kläui Mathias , Beach Geoffrey S. D. 
Published: October 2018

AbstractMagnetic skyrmions promise breakthroughs in future memory and computing devices due to their inherent stability and small size. Their creation and current driven motion have been recently observed at room temperature, but the key mechanisms of their formation are not yet well‐understood. Here it is shown that in heavy metal/ferromagnet heterostructures, pulsed currents can drive morphological transitions between labyrinth‐like, stripe‐like, and skyrmionic states. Using high‐resolution X‐ray microscopy, the spin texture evolution with temperature and magnetic field is imaged and it is demonstrated that with transient Joule heating, topological charges can be injected into the system, driving it across the stripe‐skyrmion boundary. The observations are explained through atomistic spin dynamic and micromagnetic simulations that reveal a crossover to a global skyrmionic ground state above a threshold magnetic field, which is found to decrease with increasing temperature. It is demonstrated how by tuning the phase stability, one can reliably generate skyrmions by short current pulses and stabilize them at zero field, providing new means to create and manipulate spin textures in engineered chiral ferromagnets.
Nanoparticle‐Laden Macrophages for Tumor‐Tropic Drug Delivery
Authors: Zhang Weizhong , Wang Mengzhe , Tang Wei , Wen Ru , Zhou Shiyi , Lee Chaebin , Wang Hui , Jiang Wen , Delahunty Ian Michael , Zhen Zipeng , Chen Hongmin , Chapman Matthew , Wu Zhanhong , Howerth Elizabeth W. , Cai Houjian , Li Zibo , Xie Jin 
Published: October 2018

AbstractMacrophages hold great potential in cancer drug delivery because they can sense chemotactic cues and home to tumors with high efficiency. However, it remains a challenge to load large amounts of therapeutics into macrophages without compromising cell functions. This study reports a silica‐based drug nanocapsule approach to solve this issue. The nanocapsule consists of a drug–silica complex filling and a solid silica sheath, and it is designed to minimally release drug molecules in the early hours of cell entry. While taken up by macrophages at high rates, the nanocapsules minimally affect cell migration in the first 6–12 h, buying time for macrophages to home to tumors and release drugs in situ. In particular, it is shown that doxorubicin (Dox) as a representative drug can be loaded into macrophages up to 16.6 pg per cell using this approach. When tested in a U87MG xenograft model, intravenously (i.v.) injected Dox‐laden macrophages show comparable tumor accumulation as untreated macrophages. Therapy leads to efficient tumor growth suppression, while causing little systematic toxicity. This study suggests a new cell platform for selective drug delivery, which can be readily extended to the treatment of other types of diseases.
A Facile, Low‐Cost Hot‐Pressing Process for Fabricating Lithium–Sulfur Cells with Stable Dynamic and Static Electrochemistry
Authors: Chung Sheng‐Heng , Lai Ke‐Yu , Manthiram Arumugam 
Published: October 2018

AbstractLithium–sulfur batteries are among the most promising low‐cost, high‐energy‐density storage devices. However, the inability to host a sufficient amount of sulfur in the cathode while maintaining good electrochemical stability under a lean electrolyte condition has limited the progress. The main cause of these challenges is the sensitivity of the sulfur cathode to the cell‐design parameters (i.e., the amount of sulfur and electrolyte) and the experimental testing conditions (i.e., cycling rates and analysis duration). Here, a hot‐pressing method is presented that effectively encapsulates a high amount of sulfur in the cathode within only 5 s, resulting in high sulfur loading and content of, respectively, 10 mg cm−2 and 65 wt%. The hot‐pressed sulfur (HPS) cathodes exhibit superior dynamic and static electrochemical performance under a broad cycling‐rate (C/20–1C rates) and low electrolyte/sulfur ratio (6 µL mg−1) conditions. The dynamic cell stability is demonstrated by high gravimetric and areal capacities of, respectively, 415–730 mAh g−1 and 7–12 mAh cm−2 at C/20–1C rates with a high capacity retention of over 70% after 200 cycles. The static cell stability is demonstrated by excellent shelf life with low self‐discharge and stable cycle life on storing for over one year.
Oxygen Vacancies Allow Tuning the Work Function of Vanadium Dioxide
Authors: Wang Rongbin , Katase Takayoshi , Fu Ke‐Ke , Zhai Tianshu , Yang Jiacheng , Wang Qiankun , Ohta Hiromichi , Koch Norbert , Duhm Steffen 
Published: October 2018

AbstractThe evolution of electron valence bands, core levels, and work function of vanadium dioxide (VO2) thin films upon argon ion sputtering and annealing, as commonly done to obtain atomically clean surfaces, with and without low‐pressure oxygen atmosphere during annealing is investigated by ultraviolet and X‐ray photoemission spectroscopy. Both sputtering and annealing in vacuum introduce lower oxidation state V species, leading to an increased intensity of V 3d derived bands close to the Fermi level. Such oxygen deficient surfaces exhibit low work function values as low as 4.40 eV. Annealing the sample under low‐pressure oxygen atmosphere (few times 10−4 mbar partial O2 pressure) results in stoichiometric VO2 surfaces with a high work function of up to 6.70 eV. Moreover, the work function of the VO2 can be continuously tuned between the high and low limits by adjusting the atomic ratio of oxygen and vanadium at the surface. Appropriately adjusted VO2 can thus be employed as moderate electron as well as superior hole injecting electrode material in electronic and optoelectronic devices.
Robust and Flexible Micropatterned Electrodes and Micro‐Supercapacitors in Graphene–Silk Biopapers
Authors: Ma Ruilong , Gordon Daniel , Yushin Gleb , Tsukruk Vladimir V. 
Published: October 2018

AbstractRobust and flexible micro‐supercapacitors based upon a graphene oxide–silk layered bionanocomposite is reported. Generation of micropatterned electrodes with sub‐micrometer spatial resolution is accomplished using a novel resist‐stenciling technique, enabling the transfer of complex microcircuit designs to a graphene oxide–silk layered substrate as chemically reduced features microfeatures across wafer‐length scales. Resist‐stenciling can produce micropatterned reduction features with over ten times the feature density compared to techniques such as laser‐scribing or screen printing. As a proof‐of‐concept, resist‐stenciling is used to fabricate the first 2D micro‐supercapacitors integrated into a layered graphene bionanocomposite. These demonstrate a specific capacitance of ≈128 F g−1, good capacitance retention under charge cycling (87.5% after 2000 cycles), and repeated mechanical bending without failure. Resist‐stenciling leverages tools currently in use by the microelectronics industry to enable the scalable, high‐resolution conversion of layered nanocomposites into microelectronic circuit, storage, and sensing elements.
Development and Characterization of 3D Printable Thermite Component Materials
Authors: Durban Matthew M. , Golobic Alexandra M. , Bukovsky Eric V. , Gash Alexander E. , Sullivan Kyle T. 
Published: October 2018

AbstractAdditive manufacturing (AM) has recently shown great promise as a means to tailor a wide range of material properties, both quasi‐static and dynamic. An example of controlling the dynamic behavior is to tailor the chemical energy release rate in composite energetic materials such as thermites – which are a subset of pyrotechnics that use a metal fuel and a metal oxide as an oxidizer. Since these materials are most hazardous once finely mixed, the approach taken here is to formulate the fuel and oxidizer separately such that they can be mixed on‐the‐fly. Herein, the development, formulation, and characterization of two respective aqueous 3D printable inks consisting of Al and CuO are discussed. The rheological properties and ability of the material to span gaps are characterized. To demonstrate that the materials could be mixed and sustain a reaction, the inks are fed into a static mixing nozzle and extruded into a high‐aspect ratio test strip. Upon drying, the material can be ignited and sustain a propagation through the part. These results present a facile, and safe, way to AM thermite which can be used for more detailed follow on studies looking at the role of architecture on the reactivity.
Graphene‐Based Planar Microsupercapacitors: Recent Advances and Future Challenges
Authors: Liang Jiaxing , Mondal Anjon Kumar , Wang Da‐Wei , Iacopi Francesca 
Published: October 2018

AbstractThe continuous development of integrated electronics such as maintenance‐free biosensors, remote and mobile environmental sensors, wearable personal electronics, nanorobotics etc. and their continued miniaturization has led to an increasing demand for miniaturized energy storage units. Microsupercapacitors with graphene electrodes hold great promise as miniaturized, integrated power sources thanks to their fast charge/discharge rates, superior power performance, and long cycling stability. In addition, planar interdigitated electrodes also have the capability to reduce ion diffusion distances leading to a greatly improved electrochemical performance. Either as standalone power sources or complementing energy harvesting units, it is expected that graphene‐based microsupercapacitors will play a key role as miniaturized power sources in electronic microsystems. This review highlights the recent development, challenges, and perspectives in this area, with an emphasis on the link between material and geometry design of planar graphene‐based electrodes and their electrochemical performance and integrability.
Selective Oxidation and Carbonization by Laser Writing into Porous Silicon
Authors: Keating Adrian , Sun Xiao 
Published: October 2018

AbstractThe selective formation of either oxidized or carbonized features into 2.5 µm thick porous silicon (PS) films using laser writing at a wavelength of 405 nm is demonstrated. Oxidized features are formed in air while carbonized features are achieved during the flow of propane at 600 sccm. Voids which have been previously associated with the use of propane are not observed, largely due to the rapid heating and high flow rates achieved in the experiment. Carbonized regions with feature widths down to 1.8 µm are achieved and chemical resistance to both hydrofluoric acid and potassium hydroxide is demonstrated. Once carbonized regions are formed, the surrounding areas can be overwritten in air to convert the surrounding regions into oxidized PS allowing films to be created with as‐fabricated, oxidized and carbonized regions. Energy dispersive X‐ray and Raman analysis confirms the presence of carbon within the written structures. At high optical powers, cracking around the carbonized features is observed which is attributed to a contraction of the film. Such cracking is not observed during selective oxidation of features. This work significantly enhances the ability to engineer and pattern the composition of PS films enabling selective control of the material's properties and functionality.
Piezoelectric Buckled Beam Array on a Pacemaker Lead for Energy Harvesting
Authors: Dong Lin , Wen Chunsheng , Liu Yin , Xu Zhe , Closson Andrew B. , Han Xiaomin , Escobar Gladys Patricia , Oglesby Meagan , Feldman Marc , Chen Zi , Zhang John X. J. 
Published: October 2018

AbstractSelf‐sustainable energy generation represents a new frontier to significantly extend the lifetime and effectiveness of implantable biomedical devices. In this work, a piezoelectric energy harvester design is employed to utilize the bending of the lead of a cardiac pacemaker or defibrillator for generating electrical energy with minimal risk of interfering with cardiovascular functions. The proposed energy harvester combines flexible porous polyvinylidene fluoride–trifluoroethylene thin film with a buckled beam array design for potentially harvesting energy from cardiac motion. Systematic in vitro experimental evaluations are performed by considering complex parameters in practical implementations. Under various mechanical inputs and boundary conditions, the maximum electrical output of this energy harvester yields an open circuit voltage (peak to peak) of 4.5 V and a short circuit current (peak to peak) of 200 nA, and that energy is sufficient to self‐power a typical pacemaker for 1 d. A peak power output of 49 nW is delivered at an optimal resistor load of 50 MΩ. The scalability of the design is also discussed, and the reported results demonstrate the energy harvester's capability of providing significant electrical energy directly from the motions of pacemaker leads, suggesting a paradigm for biomedical energy harvesting in vivo.