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  • As a new two-dimensional (2D) material, monolayer ruthenium oxide (RuO2) nanosheets (NSs) have distorted h-MX2 type crystal structures that lead to semiconducting properties and good optical transmittance. This study suggests that monolayer RuO2 can be useful in applications of flexible optoelectronics.

    • Dong-Su Ko
    • Woo-Jin Lee
    • Jong Wook Roh
    Article Open Access
  • An amphiphilic dendrimer engineered nanocarrier system (ADENS) possessing a unique hollow core/shell structure is developed, in which siRNA is incorporated in the hydrophilic cavity and paclitaxel is abundantly depoted in the hydrophobic interlayer. Then, the ADENS is modified by tumor microenvironment-sensitive polypeptides (TMSP). The TMSP-ADENS shows enhanced cellular uptake, tumor penetration and accumulation in a MMP-2/9-triggered mechanism. The TMSP-ADENS provides a potential strategy for effective co-delivery of siRNA and paclitaxel for anti-tumor therapy in a synergistic manner.

    • Xin Li
    • A-ning Sun
    • Xian-rong Qi
    Article Open Access
  • Large inhomogeneous electronic states in rare-earth-doped CaFe2As2 produce striking results of manipulating the superconducting phases via current-driven magnetic state. Magnetization hysteresis loops at superconducting state (2 K) and normal state (50 K) for La-doped CaFe2As2 are largely changed by the electric current because their high-Tc regions are localized. Current path between high-Tc regions is considered as a long wire, thus current-induced large magnetic field around the path can modulate the magnetic state in normal/weak superconducting regions. These observations provide new insights into the role of Fe in the Fe-based superconductors and ideas for the design of new superconducting devices.

    • Soon-Gil Jung
    • Soohyeon Shin
    • Tuson Park
    Article Open Access
  • A high density of “accordion-like” silver nanorod array over a large area (~cm2) was fabricated by confining lamellar-forming polystyrene-block-poly (methyl methacrylate) copolymer (PS-b-PMMA) inside cylindrical pores of aluminum oxide (AAO) template grafted by thin neutral brush layers. After removing the AAO template, a 5 nm thick layer of silver was thermally deposited on only PS nanodomains. Owing to combination of hemispherical head and side silver rings, multiple resonances exhibited in the visible and NIR regimes. This sophisticated fabrication utilizing block copolymer self-assembly could be applied to multi-analyte detection and realization of large-scale metamaterials working at visible and NIR wavelengths.

    • Mooseong Kim
    • Jungho Mun
    • Jin Kon Kim
    Article Open Access
  • The copper nanofibrils are formed at the void inside the long continuous carbon nanotube (CNT) fiber by electroplating. Electrical conduction through the composite fiber was dominated by the nanofibrils even though their cross-sectional area is much smaller than that of CNTs. The nanofibrils could carry a very high current density due to their bamboo-like structure and the thermal dissipation through CNTs.

    • Hokyun Rho
    • Min Park
    • Sang Hyun Lee
    Article Open Access
  • A pH-responsive superwetting surface is fabricated and applied as a point-of-care testing platform for naked eye biosensing. Because of the outstanding switching between superhydrophilicity and superhydrophobicity, contact angle based biosensing method is developed for pH, urea, and glucose detection. Especially, non-invasive detection of glucose is achieved for diabetes diagnosis and exercise monitoring. Given to its low cost, instrument-free, disposable, and rapid response (within 1 s), this strategy not only provides a universal platform of point-of-care testing but also extends the industrial-scale application of bioinspired superwettability systems.

    • Zhong Feng Gao
    • Ei Ei Sann
    • Lei Jiang
    Article Open Access
  • We present piezoresistive electronic skins with tunable force sensitivity and selectivity in response to multidirectional forces (normal, shear, tensile, bending) by engineering microstructure geometries (dome, pyramid, pillar). Microdome structures present the best force sensitivities for normal, tensile, and bending stresses. On the other hand, for shear stress, micropillar structures exhibit the highest sensitivity. As proof-of-concept demonstrations, the e-skins are used for wearable healthcare devices to precisely monitor various bio-signals including sound, human breath, and artery/carotid pulse pressures.

    • Jonghwa Park
    • Jinyoung Kim
    • Hyunhyub Ko
    Article Open Access
  • A creative approach to substantially enhance both the strength and ductility of SLM-printed metal parts was successfully demonstrated on the ubiquitous marine-grade stainless steel 316L. The new discovery improves the strength and ductility of stainless steel parts by ~16% and 40% compared with the typical 3D printing process and conventional manufacturing methods. Control of the crystallographic texture is key for this breakthrough, which was achieved by tailoring the geometrical features of the melt pool involved in the laser-based 3D printing process. The desired <011> crystallographic texture favors the activation of the nano-twinning mechanism, which simultaneously enhances the strength and ductility.

    • Zhongji Sun
    • Xipeng Tan
    • Chee Kai Chua
    Article Open Access
  • Cryothermal cycling can induce rejuvenation as well as relaxation of metallic glasses. The surface apparent Young’s modulus and its spatial distribution width increase after the treatment, while in bulk effect depends on the glass composition. This increase is temporary and disappears after some time of room temperature aging. Effect is connected with a large distribution of relaxation times in metallic glasses due to their heterogeneous structure and the formation of complex native oxide on the glass surface. Cryothermal cycling can improve or degrade the plasticity of metallic glasses and the atomic bond structure determines the outcome of the treatment.

    • Sergey V. Ketov
    • Artem S. Trifonov
    • Alan Lindsay Greer
    Article Open Access
  • In this study, the transparent polymer resin in visible wavelength ranges yet ironically be curable by visible light is introduced for stereolithography three-dimensional printings. The key is to use the photoinitiator, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (DPTBP), which generates radicals at the edge wavelength of visible light ranges (~420 nm). The developed resin has high transparency, commercial dyes incorporations, and superior mechanical strength to the existing resins.

    • Hong Key Park
    • Mikyung Shin
    • Haeshin Lee
    Article Open Access
  • The present electric-field induced phase transition from non-polar incommensurate to ferroelectric commensurate phase in Pb-free dielectrics with tungsten bronze structure has been proved to be the structural origin of the pinched P-E loops. This new mechanism for pinched P-E hysteresis loops in ferroelectrics not only indicates a new direction to develop Pb-free ferroelectric materials for energy storage but also contributes significantly to physical understanding of ferroelectricity in materials with tungsten bronze structure.

    • Kun Li
    • Xiao Li Zhu
    • Xiang Ming Chen
    Article Open Access
  • Ab initio calculations reveal that the rate-limiting transition state during a dynamical process in a semiconductor or an insulator can have a different charge state from that of the initial ground state, rather than the same charge state as generally assumed. Such “transition state redox” effect may significantly lower the activation barrier and can be realized through the hopping of an initial excited state and possibly an electron exchange with the bulk during the dynamical process.

    • Guangfu Luo
    • Thomas F. Kuech
    • Dane Morgan
    Article Open Access
  • Fe-CaSiO3 composite scaffolds (30CS) were designed via 3D printing technique. Firstly, 30CS scaffolds possessed high compressive strength to provide sufficient mechanical support in bone cortical defects; Secondly, a synergistic therapy of photothermal and ROS achieved enhanced tumor therapeutic effect in vitro and in vivo; Thirdly, the presence of CaSiO3 in the composite scaffolds enforced the degradation performance and stimulated proliferation and differentiation of rBMSCs and further promoted bone forming in vivo. Such 30CS scaffolds with high compressive strength can function as versatile and efficient biomaterials for the future regeneration of cortical bone defects and therapy of bone cancer.

    • Hongshi Ma
    • Tao Li
    • Chengtie Wu
    Article Open Access
  • We suggest synaptic devices using cation migration along thickness direction in a new class of 2D layered materials. An electrochemically active metal, such as Ag and Cu, is used for the operation of the synaptic device and chromium thiophosphate (CrPS4) single crystal is used as an electrolyte material. Multi-stable resistive states, short-term plasticity, and long-term potentiation are observed by controlling external voltage pulse with height smaller than 0.3 V. Given that simple mechanical exfoliation can generate very thin CrPS4 layers, the vertical Ag/CrPS4/Au capacitor offers a promising inorganic synaptic device compatible with next-generation flexible neuromorphic technology.

    • Mi Jung Lee
    • Sangik Lee
    • Bae Ho Park
    Article Open Access