Research articles

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  • Indium-free un-doped tin dioxide (SnO2) serves as a transparent conducting electrode for indoor organic photovoltaics (OPVs). SnO2 OPV systems demonstrate superior indoor performance compared with indium tin oxide (ITO)-based systems. SnO2-based OPV systems shows 14.6% efficiency under 1000 lx of LED illumination. Low-cost SnO2 can be a promising substitute for expensive ITOs in indoor OPV systems.

    • Jung-Hoon Lee
    • Young-Jun You
    • Jae Won Shim
    Article Open Access
  • By combining the MoS2 channel with the PEDOT:PSS floating layer, a new concept device is proposed. This work demonstrates optoelectronic memory operation with high mechanical endurance through a 1,000-cycle bending test, which also offers multilevel memory programming operation based on light intensity and color.

    • Seongin Hong
    • Junwoo Park
    • Sunkook Kim
    Article Open Access
  • We investigated the scintillation performance of centimeter lead-halide Cs4PbBr6 single crystal synthesized by a facile solution process. Cs4PbBr6 single crystal have been demonstrated with fast scintillation decay time, low detection limit, and without hygroscopic, which makes it ideal for indirection radiation detection applications. The alpha pulse height spectroscopy deconvoluted into two Gaussian functions were obtained. The clear X-ray imaging of a standard pattern plate with 600 μm interval width under a low dose rate below 3.3 μGyair/s was collected. All these results indicate that this low-cost Cs4PbBr6 SCs scintillator is expected to be a promising low-dose X-ray imaging material.

    • Yang Li
    • Wenyi Shao
    • Qiang Xu
    Article Open Access
  • Metallic phase transition metal dichalcogenides quantum dots show different pathways of optical charge excitation and decay according to the size and sort of defects, resulting into the large Stoke shift, two bands for charge excitation, and TRPL peak shift. This result is mainly ascribed to the valance band splitting and the emerging defect states originated from atomic vacancy of basal plane and edge oxidation.

    • Bo-Hyun Kim
    • Min-Ho Jang
    • Sung-Ho Song
    Article Open Access
  • This work demonstrates medium-entropy alloy (MEA) hollow nanolattices with high toughness and resilience, by leveraging size-induced ductility and rationally engineered MEA microstructural defects, suggesting a new pathway for lightweight mechanical metamaterials with simultaneous high strength, toughness, and recoverability for engineering applications.

    • James Utama Surjadi
    • Xiaobin Feng
    • Yang Lu
    Article Open Access
  • In this work, Xu et al. established an in vitro model to assess the responses of astrocytes to the changes of matrix stiffness that may be related to pathophysiology. The investigated hydrogel backbones are composed of collagen type I and alginate. The stiffness of these hybrid hydrogels can be dynamically tuned through the association or dissociation of alginate chains, respectively. It was found that astrocytes obtain different phenotypes when cultured in hydrogels of different stiffness. The obtained phenotypes can be switched in situ when changing matrix stiffness in the presence of cells. Specifically, matrix stiffening reverts astrogliosis, whereas matrix softening initiates astrocytic activation in 3D.

    • Yan Hu
    • Guoyou Huang
    • Feng Xu
    Article Open Access
  • Wide- and narrow-bandgap semiconductor nanostructures were monolithically integrated on graphene layers by direct heteroepitaxial growth. The structural, optical, and electrical characteristics of the hybrid nanostructures were investigated. Furthermore, dual-wavelength photodetectors sensitive to both ultraviolet and mid-infrared wavelengths were fabricated using the hybrid nanostructures.

    • Youngbin Tchoe
    • Janghyun Jo
    • Gyu-Chul Yi
    Article Open Access
  • This paper reports a universal strategy for easily preparing hydrogels that are tough and stretchable without any special structures or complicated processes. Tough and stretchable hydrogels are prepared by tuning the polymerization conditions to form networks with many polymer chain entanglements to achieve energy dissipation. The strategy allows us to overcome the limitation of low mechanical performance, which leads to the wide practical use of hydrogels.

    • Chisa Norioka
    • Yuino Inamoto
    • Takashi Miyata
    Article Open Access
  • We demonstrate intracellular GaN microrod lasers for cell labeling applications. GaN microrods show excellent lasing signals under intracellular conditions with a low lasing threshold (~270 kW/cm2). The lasing spectra from individual intracellular microrods are distinguishable because each GaN microrod has different lasing peak wavelength, mode spacings, and relative PL intensities. This result suggests that GaN microrods can be candidates for cell labeling applications.

    • Minho S. Song
    • Hyeonjun Baek
    • Gyu-Chul Yi
    Article Open Access
  • Flexible and high-energy-density lithium-sulfur (Li-S) batteries based on all-fibrous sulfur cathodes and separators have structural uniqueness and chemical functionality, exhibit a high gravimetric energy density of 435 Wh kg−1 per cell and excellent reliability in terms of electrochemical performance with a slow decay rate of < 1% per cycle, even under severe mechanical stress/deformation conditions.

    • Jun-Woo Park
    • Seong-Chan Jo
    • Kang-Jun Baeg
    Article Open Access
  • The biosynthesis and characterization of a new biodegradable plastic, poly(3-hydroxy-2-methylbutyrate) [P(3H2MB)], which is a member of the bacterial polyhydroxyalkanoate (PHA) family whose members include an α-methylated monomer unit, were investigated. Biosynthesized P(3H2MB) exhibited the highest melting temperature (197 °C) among the biosynthesized PHAs and improved thermal resistance. It also exhibited improved crystallization behavior and mechanical flexibility nearly equal to those of isotactic polypropylene (iPP). The superior physical properties of P(3H2MB) have the potential to open new avenues for the production of high-performance biodegradable plastics for replacing petroleum-based bulk commodity plastics.

    • Sho Furutate
    • Junichi Kamoi
    • Takeharu Tsuge
    Article Open Access
  • In this study, ectomesenchymal stem cells (EMSCs) were modified with the transglutaminase 2 (TG2) genes and tested for their ability to enhance bone regeneration on fibrin scaffold. In vitro analyses revealed that osteogenic differentiation of the EMSCs on the fibrin scaffold was promoted by TG2 expression. Transplanting fibrin scaffold loaded with TG2 gene-modified EMSC into bone defects on rat skull induced significantly faster bone regeneration compared with non-genetically modified EMSC.

    • Wentao Shi
    • Yunduan Que
    • Naiyan Lu
    Article Open Access
  • Single-particle fluorescence imaging is used to monitor dynamic processes that occur during patterned photopolymerization of liquid-crystalline monomers. Spatial gradient of chemical potential created at the border of bright and dark regions by structured illumination leads to mutual diffusion of polymers and monomers. Fluorescence of single quantum dots doped into the monomers visualizes highly directional mass flow from the illuminated region where the photopolymerization proceeds toward a masked unpolymerized region. The flow-induced orientation of the polymers is subsequently fixed by completion of the polymerization reaction, resulting in a mesoscopic aligned area of the polymer film.

    • Keisuke Ueda
    • Miho Aizawa
    • Martin Vacha
    Article Open Access
  • Here, we investigated the details of magnetic skyrmion bubble domain formation by a tilted magnetic field. The in-plane component of the magnetic field serves to reduce the width of the stripe domain. These stripe domains are easily broken and bubble domains are formed. We have demonstrated that the key parameter determining the stripe domain instability is the stripe width, regardless of other material parameters. This bubble generation method can be applicable to generic magnetic films with perpendicular magnetic anisotropy. Our work will facilitate the development of skyrmion-based devices by offering a general method for controlling a large skyrmion population.

    • Kyoung-Woong Moon
    • Seungmo Yang
    • Chanyong Hwang
    Article Open Access
  • Schematic illustration showing our overall approach, studies performed, and envisioned application. Our strategy combines biomechanical and biochemical cues from a mechanically graded biomaterial and GF biopatterning, respectively, to spatially control bone- and tendon-like differentiation. Here, experiments (i) characterized our biomaterial, (ii) investigated the interplay between biomechanical and biochemical cues in vitro, and (iii) assessed the ability of our GF-biopatterned and biphasic biomaterial to spatially control bone- and tendon-like tissue formation in vivo. The envisioned goal of this study is to develop a biomaterial for treating large-to-massive tendon injuries.

    • Dan Wang
    • Dai Fei Elmer Ker
    • Yunzhi Peter Yang
    Article Open Access
  • We facilely prepared temperature-responsive MXene nanosheet/nanobelt fibers carrying vitamin E with a controllable release ability for wound healing, tissue engineering, and much broader applications.

    • Lin Jin
    • Xiaoqing Guo
    • Xingcai Zhang
    Article Open Access
  • Toxin proteins can cause physical damage, biochemical degradation and signaling interruption in mammals, leading to disabilities and even death. Most of the current antitoxins are developed against specific toxins. The broad-spectrum antitoxic platforms are still rare. Here, we developed a reactive conjugated polymer, PPV-NHS, which selectively reacted with basic proteins and reduced the activity of these attached proteins. PPV-NHS showed excellent inhibition effect on neurotoxicity and hemolysis caused by α-bungarotoxin and cardiotoxin in vitro and in vivo. This work represents the rational design of functionalized conjugated polymers for anti-virulence therapy with both high efficiency and broad applicability.

    • Han Sun
    • Jing Liu
    • Shu Wang
    Article Open Access
  • Integration and design of existing function units into specialized architectures might show combined and even improved performances of the original components. Here we describe a serial of synthetic antibacterial complexes composed of melittin, a natural antimicrobial peptide, and poly(ethylene glycol), a clinical available agent, as building blocks, which show potent and architecture-modulated antibacterial activity against multidrug-resistant pathogens and decreased cytotoxicity.

    • Bing Yuan
    • Jiaojiao Liu
    • Zhenhui Kang
    Article Open Access
  • In this work, a substrate with dual anisotropy were prepared by combination of 3D printing and magnetic field-induced magnetic nanoparticle assembly. ADSCs cultured on this substrates have significantly higher osteogenic markers expression and more calcium nodules formation was also found, suggesting a stronger tendency of toward osteogenic differentiation of ADSCs. RNA-seq data revealed alteration of that alterations in kinase signaling pathway transduction, cell adhesion and cytoskeletalon reconstruction may account for the elevated osteogenic induction capacity.

    • Ke Hu
    • Tingting Yu
    • Ning Gu
    Article Open Access
  • A resistive switching device is fabricated using nanostructured nickel cobaltite for high-density data storage and synaptic learning applications. The active switching layer of the device consists of quasi-hexagonal porous nanosheets that enable smooth charge transport. The device shows voltage tunable and forming-free resistive switching effect and non-ideal memristive properties. The rational design of the device helps to show controlled multilevel resistive switching property and thereby switch between three conductive states. The analog switching of the device helps to mimic specific neural network behavior, such as the potentiation, depression and four spike-timing-dependent plasticity rules.

    • Tukaram D. Dongale
    • Atul C. Khot
    • Tae Geun Kim
    Article Open Access