Phase diagram and crossover phases of topologically ordered graphene zigzag nanoribbons: role of localization effects.

We computed the phase diagram of zigzag graphene nanoribbons as a function of on-site repulsion, doping, and disorder strength. The topologically ordered phase undergoes topological phase transitions into crossover phases, which are new disordered phases with non-universal topological entanglement entropy that exhibits significant variance. We explored the nature of non-local correlations in both the topologically ordered and crossover phases. In the presence of localization effects, strong on-site repulsion and/or doping weaken non-local correlations between the opposite zigzag edges of the topologically ordered phase. In one of the crossover phases, bothe-/2solitonic fractional charges and spin-charge separation were absent; however, charge-transfer correlations between the zigzag edges were possible. Another crossover phase contains solitonice-/2fractional charges but lacks charge transfer correlations. We also observed properties of non-topological, strongly disordered, and strongly repulsive phases. Each phase on the phase diagram exhibits a different zigzag-edge structure. Additionally, we investigated the tunneling of solitonic fractional charges under an applied voltage between the zigzag edges of undoped topologically ordered zigzag ribbons, and found that it may lead to a zero-bias tunneling anomaly.

Role of GO and Photoinitiator Concentration on Curing Behavior of PEG-Based Polymer for DLP 3D Printing.

Photocuring kinetics in photopolymerization-based three-dimensional (3D) printing processes have gained significant attention because they determine the final dimension accuracy of the printed structures. In this study, the curing kinetics of liquid-light-curable resins, including water-dispersed graphene oxide (GO) and ultraviolet (UV)-cured acrylic resins, were investigated during digital light processing (DLP) 3D printing. Various stable composites of water-dispersed GO and UV-cured acrylic resin were prepared to fabricate 3D structures for cure-depth measurements. Several factors, including the UV-exposure conditions, photoinitiator concentration, and composition of the photopolymer resin, were found to significantly affect the cure-depth characteristics of the printed structures. The photocuring depth of the polymeric resin system was investigated as a function of the photoinitiator concentration. In addition, the study showed that the introduction of GO played a significant role in controlling the performance of the highly cross-linked network and the thickness of the cured layer. The curing characteristics of functional photocurable polymer-based DLP 3D printing contribute to process development and improvement of the quality of printed microstructures for industrial applications.

Controlled Electronic and Magnetic Landscape in Self-Assembled Complex Oxide Heterostructures.

Complex oxide heterointerfaces contain a rich playground of novel physical properties and functionalities, which give rise to emerging technologies. Among designing and controlling the functional properties of complex oxide film heterostructures, vertically aligned nanostructure (VAN) films using a self-assembling bottom-up deposition method presents great promise in terms of structural flexibility and property tunability. Here, the bottom-up self-assembly is extended to a new approach using a mixture containing a 2Dlayer-by-layer film growth, followed by a 3D VAN film growth. In this work, the two-phase nanocomposite thin films are based on LaAlO3 :LaBO3 , grown on a lattice-mismatched SrTiO3001 (001) single crystal. The 2D-to-3D transient structural assembly is primarily controlled by the composition ratio, leading to the coexistence of multiple interfacial properties, 2D electron gas, and magnetic anisotropy. This approach provides multidimensional film heterostructures which enrich the emergent phenomena for multifunctional applications.

New disordered anyon phase of doped graphene zigzag nanoribbon.

We investigate interacting disordered zigzag nanoribbons at low doping, using the Hubbard model to treat electron interactions within the density matrix renormalization group and Hartree-Fock method. Extra electrons that are inserted into an interacting disordered zigzag nanoribbon divide into anyons. Furthermore, the fractional charges form a new disordered anyon phase with a highly distorted edge spin density wave, containing numerous localized magnetic moments residing on the zigzag edges, thereby displaying spin-charge separation and a strong non-local correlation between the opposite zigzag edges. We make the following new predictions, which can be experimentally tested: (1) In the low doping case and weak disorder regime, the soft gap in the tunneling density of states is replaced by a sharp peak at the midgap energy with two accompanying peaks. The [Formula: see text] fractional charges that reside on the boundary of the zigzag edges are responsible for these peaks. (2) We find that the midgap peak disappears as the doping concentration increases. The presence of [Formula: see text] fractional charges will be strongly supported by the detection of these peaks. Doped zigzag ribbons may also exhibit unusual transport, magnetic, and inter-edge tunneling properties.

Progressive and Stable Synaptic Plasticity with Femtojoule Energy Consumption by the Interface Engineering of a Metal/Ferroelectric/Semiconductor.

In the era of "big data," the cognitive system of the human brain is being mimicked through hardware implementation of highly accurate neuromorphic computing by progressive weight update in synaptic electronics. Low-energy synaptic operation requires both low reading current and short operation time to be applicable to large-scale neuromorphic computing systems. In this study, an energy-efficient synaptic device is implemented comprising a Ni/Pb(Zr0.52 Ti0.48 )O3 (PZT)/0.5 wt.% Nb-doped SrTiO3 (Nb:STO) heterojunction with a low reading current of 10 nA and short operation time of 20-100 ns. Ultralow femtojoule operation below 9 fJ at a synaptic event, which is comparable to the energy required for synaptic events in the human brain (10 fJ), is achieved by adjusting the Schottky barrier between the top electrode and ferroelectric film. Moreover, progressive domain switching in ferroelectric PZT successfully induces both low nonlinearity/asymmetry and good stability of the weight update. The synaptic device developed here can facilitate the development of large-scale neuromorphic arrays for artificial neural networks with low energy consumption and high accuracy.

Heterointerface Effect on Two-Step Nucleation Mechanism of Bi Particles.

The nucleation and crystallization of Bi particles on two matrices, crystalline bismuth sulfide (c-Bi2S3) and amorphized bismuth titanium oxide (a-Bi12TiO20), were studied by using in situ transmission electron microscopy (TEM) analysis. The atomic structures of the Bi particles were monitored by acquiring high-resolution TEM images in real time. The Bi particles were grown on c-Bi2S3 and a-Bi12TiO20 via a two-step nucleation mechanism; dense liquid clusters were clearly observed at the initial stage of nucleation, and the coalescence of clusters was frequently observed during the growth. However, the nucleation and crystallization behaviors of Bi particles were governed by the matrix; in particular, the evolution of their morphology and atomic structure was confined on c-Bi2S3 but free from matrix effects on a-Bi12TiO20. The matrix effect on the two-step nucleation mechanism was demonstrated from a thermodynamic point of view.

Thermodynamic patterns duringin-situheating of InAs nanowires encapsulated in Al2O3shells.

Understanding the dynamic thermal behavior of nanomaterials based on their unique physical and chemical properties is critical for their applications. In this study, the thermal behavior of single-crystalline InAs nanowires in an amorphous Al2O3shell was investigated by conductingin situheating experiments in a transmission electron microscope. Two different thermodynamic patterns were observed during thein situheating experiments: (1) continuous vaporization and condensation simultaneously at temperatures lower than 838.15 K, and (2) pure evaporation at temperatures higher than 878.15 K. During the simultaneous condensation and vaporization in closer areas in a single InAs nanowire, the front edge of the vaporization was flat, while that of the condensation actively changed with time and temperature. Pure vaporization was conducted via layer-by-layer evaporation followed by three-dimensional vaporization at the final stage. The thermal behaviors of the InAs nanowires were demonstrated from a thermodynamic point of view.

AlzGPS: a genome-wide positioning systems platform to catalyze multi-omics for Alzheimer's drug discovery.

BACKGROUND: Recent DNA/RNA sequencing and other multi-omics technologies have advanced the understanding of the biology and pathophysiology of AD, yet there is still a lack of disease-modifying treatments for AD. A new approach to integration of the genome, transcriptome, proteome, and human interactome in the drug discovery and development process is essential for this endeavor. METHODS: In this study, we developed AlzGPS (Genome-wide Positioning Systems platform for Alzheimer's Drug Discovery, https://alzgps.lerner.ccf.org ), a comprehensive systems biology tool to enable searching, visualizing, and analyzing multi-omics, various types of heterogeneous biological networks, and clinical databases for target identification and development of effective prevention and treatment for AD. RESULTS: Via AlzGPS: (1) we curated more than 100 AD multi-omics data sets capturing DNA, RNA, protein, and small molecule profiles underlying AD pathogenesis (e.g., early vs. late stage and tau or amyloid endophenotype); (2) we constructed endophenotype disease modules by incorporating multi-omics findings and human protein-protein interactome networks; (3) we provided possible treatment information from ~ 3000 FDA approved/investigational drugs for AD using state-of-the-art network proximity analyses; (4) we curated nearly 300 literature references for high-confidence drug candidates; (5) we included information from over 1000 AD clinical trials noting drug's mechanisms-of-action and primary drug targets, and linking them to our integrated multi-omics view for targets and network analysis results for the drugs; (6) we implemented a highly interactive web interface for database browsing and network visualization. CONCLUSIONS: Network visualization enabled by AlzGPS includes brain-specific neighborhood networks for genes-of-interest, endophenotype disease module networks for omics-of-interest, and mechanism-of-action networks for drugs targeting disease modules. By virtue of combining systems pharmacology and network-based integrative analysis of multi-omics data, AlzGPS offers actionable systems biology tools for accelerating therapeutic development in AD.

Radiation-Activated PI3K/AKT Pathway Promotes the Induction of Cancer Stem-Like Cells via the Upregulation of SOX2 in Colorectal Cancer.

The current treatment strategy for patients with aggressive colorectal cancer has been hampered by resistance to radiotherapy and chemotherapy due to the existence of cancer stem-like cells (CSCs). Recent studies have shown that SOX2 expression plays an important role in the maintenance of CSC properties in colorectal cancer. In this study, we investigated the induction and regulatory role of SOX2 following the irradiation of radioresistant and radiosensitive colorectal cancer cells. We used FACS and western blotting to analyze SOX2 expression in cells. Among the markers of colorectal CSCs, the expression of CD44 increased upon irradiation in radioresistant cells. Further analysis revealed the retention of CSC properties with an upregulation of SOX2 as shown by enhanced resistance to radiation and metastatic potential in vitro. Interestingly, both the knockdown and overexpression of SOX2 led to increase in CD44+ population and induction of CSC properties in colorectal cancer following irradiation. Furthermore, selective genetic and pharmacological inhibition of the PI3K/AKT pathway, but not the MAPK pathway, attenuated SOX2-dependent CD44 expression and metastatic potential upon irradiation in vitro. Our findings suggested that SOX2 regulated by radiation-induced activation of PI3K/AKT pathway contributes to the induction of colorectal CSCs, thereby highlighting its potential as a therapeutic target.

Accelerated decomposition of Bi2S3 nanorods in water under an electron beam: a liquid phase transmission electron microscopy study.

Evaluating the stability of semiconductor photocatalysts is critical in the development of efficient catalysts. The morphological and microstructural behaviors of nanorod-shaped Bi2S3 semiconductors in aqueous solution were studied using a liquid cell transmission electron microscopy (TEM) technique. The rapid decomposition of Bi2S3 in water was observed under electron beam irradiation during TEM. Rounded bright spots due to a reduction in thickness were observed on the Bi2S3 nanorods at the initial stage of the decomposition, and rounded dark particles appeared outside of the nanorods in the solution, continuing the decomposition. This was confirmed by analyzing the atomic structure of the newly formed small particles, which consisted of an orthorhombic Bi2S3 phase. The stability-related decomposition of the Bi2S3 nanorods was demonstrated by considering the reduction and oxidation potentials of Bi2S3 in an aqueous solution. The effect of water radiolysis by the incident electron during TEM observations on the decomposition process was also determined by considering the time-dependent concentration behavior of the chemical species. Our study therefore reflects a novel route to evaluate the stabilities of semiconductor photocatalysts, which could ultimately solve a range of energy and environmental pollution problems.

Microstructural evolution in self-catalyzed GaAs nanowires during in-situ TEM study.

The microstructural evolutions in self-catalyzed GaAs nanowires (NWs) were investigated by using in situ heating transmission electron microscopy (TEM). The morphological changes of the self-catalyst metal gallium (Ga) droplet, the GaAs NWs, and the atomic behavior at the interface between the self-catalyst metal gallium and GaAs NWs were carefully studied by analysis of high-resolution TEM images. The microstructural change of the Ga-droplet/GaAs-NWs started at a low temperature of ∼200 °C. Formation and destruction of atomic layers were observed at the Ga/GaAs interface and slow depletion of the Ga droplet was detected in the temperature range investigated. Above 300 °C, the evolution process dramatically changed with time: The Ga droplet depleted rapidly and fast growth of zinc-blende (ZB) GaAs structures were observed in the droplet. The Ga droplet was completely removed with time and temperature. When the temperature reached ∼600 °C, the decomposition of GaAs was detected. This process began in the wurtzite (WZ) structure and propagated to the ZB structure. The morphological and atomistic behaviors in self-catalyzed GaAs NWs were demonstrated based on thermodynamic considerations, in addition to the effect of the incident electron beam in TEM. Finally, GaAs decomposition was demonstrated in terms of congruent vaporization.

Ghrelin reverts intestinal stem cell loss associated with radiation-induced enteropathy by activating Notch signaling.

BACKGROUD: Exposure to high-dose radiation, such as after a nuclear accident or radiotherapy, elicits severe intestinal damage and is associated with a high mortality rate. In treating patients exhibiting radiation-induced intestinal dysfunction, countermeasures to radiation are required. In principle, the cellular event underlying radiation-induced gastrointestinal syndrome is intestinal stem cell (ISC) apoptosis in the crypts. High-dose irradiation induces the loss of ISCs and impairs intestinal barrier function, including epithelial regeneration and integrity. Notch signaling plays a critical role in the maintenance of the intestinal epithelium and regulates ISC self-renewal. Ghrelin, a hormone produced mainly by enteroendocrine cells in the gastrointestinal tract, has diverse physiological and biological functions. PURPOSE: We investigate whether ghrelin mitigates radiation-induced enteropathy, focusing on its role in maintaining epithelial function. METHODS: To investigate the effect of ghrelin in radiation-induced epithelial damage, we analyzed proliferation and Notch signaling in human intestinal epithelial cell. And we performed histological analysis, inflammatory response, barrier functional assays, and expression of notch related gene and epithelial stem cell using a mouse model of radiation-induced enteritis. RESULTS: In this study, we found that ghrelin treatment accelerated the reversal of radiation-induced epithelial damage including barrier dysfunction and defective self-renewing property of ISCs by activating Notch signaling. Exogenous injection of ghrelin also attenuated the severity of radiation-induced intestinal injury in a mouse model. CONCLUSION: These data suggest that ghrelin may be used as a potential therapeutic agent for radiation-induced enteropathy.

Evaluation of the radiation response and regenerative effects of mesenchymal stem cell-conditioned medium in an intestinal organoid system.

Intestinal organoids have recently emerged as an in vitro model relevant to the gut system owing to their recapitulation of the native intestinal epithelium with crypt-villus architecture. However, it is unclear whether intestinal organoids reflect the physiology of the in vivo stress response. Here, we systemically investigated the radiation response in organoids and animal models using mesenchymal stem cell-conditioned medium (MSC-CM), which contains secreted paracrine factors. Irradiated organoids exhibited sequential induction of viability loss and regrowth after irradiation (within 12 days), similar to the response of the native intestinal epithelium. Notably, treatment with MSC-CM facilitated the reproliferation of intestinal stem cells (ISCs) and restoration of damaged crypt-villus structures in both models. Furthermore, Wnt/Notch signaling pathways were commonly upregulated by MSC-CM, but not radiation, and pharmacologically selective inhibition of Wnt or Notch signaling attenuated the enhanced recovery of irradiated organoids, with increases in ISCs, following MSC-CM treatment. Interestingly, the expression of Wnt4, Wnt7a, and active ß-catenin was increased, but not notch family members, in MSC-CM-treated organoid after irradiation. Treatment of recombinant mouse Wnt4 and Wnt7a after irradiation improved to some extent intestinal epithelial regeneration both in vitro and in vivo. Overall, these results suggested that intestinal organoids recapitulated the physiological stress response of the intestinal epithelium in vivo. Thus, our findings provided important insights into the physiology of intestinal organoids and may contribute to the development of strategies to enhance the functional maturation of engineered organoids.

Hydrogen passivation: a proficient strategy to enhance the optical and photoelectrochemical performance of InGaN/GaN single-quantum-well nanorods.

Recently, III-nitride semiconductor nanostructures, especially InGaN/GaN quantum well nanorods (NRs), have been established as a promising material of choice for nanoscale optoelectronics and photoelectrochemical (PEC) water-splitting applications. Due to the large number of surface states, III-nitride NRs suffer from low quantum efficiency. Therefore, control of the surface states is necessary to improve device performance in real-time applications. In this work, we investigated the effect of hydrogen plasma treatment on the optical properties of InGaN/GaN single-quantum-well (SQW) NRs. The low-temperature photoluminescence (PL) studies revealed that yellow and green emissions overlapped and the yellow band is more dominant in the pristine InGaN/GaN SQW NRs. However, the emission corresponding to yellow luminescence was strongly suppressed and the green emission is more intensified in hydrogenated InGaN/GaN SQW NRs. Furthermore, the time-resolved PL spectroscopy studies revealed that the carrier lifetimes of hydrogenated InGaN/GaN SQW NRs are relatively short compared to the pristine InGaN/GaN SQW, indicating the effective reduction of non-radiative centers. From the PEC measurement, the photocurrent density of hydrogenated InGaN/GaN SQW NRs in the H2SO4 solution is found to be 5 mA cm-2 at -0.48 V versus reversible hydrogen electrode, which is 3.5-fold larger than that of pristine ones. These findings shed new light on the significance of surface treatment on the optical properties and thus nanostructured photoelectrodes for PEC applications.

Hydrogenation-produced In2O3/InN core-shell nanorod and its effect on NO2 gas sensing behavior.

In this work, for the first time, we have made InN/In2O3 core-shell heterostructure by hydrogen plasma treatment. InN nanorods (NRs) were grown by using plasma-assisted molecular beam epitaxy, and hydrogen plasma treatment was performed by using reactive ion etching at room temperature. From x-ray photoemission spectroscopy studies, it was observed that the bonding partner of In changes from N to O and N 1s completely disappeared in the hydrogenated InN NRs. Furthermore, high-resolution transmission electron microscopy revealed the formation of InN/In2O3 core-shell NRs by hydrogenation plasma treatment. The resistance of pristine InN NRs was decreased in NO2 ambient. Interestingly, the resistance of the InN/In2O3 core-shell was increased while introducing NO2 gas. InN NR surface exhibits downward band bending due to the electron accumulation, in NO2 ambient, and the surface band bending was decreased due to the increase in the bulk conduction channel. This reversed gas sensing behavior in InN/In2O3 core-shell NRs was attributed to the increase in depletion layer while reducing the conduction channel width by the absorption of NO2. The InN/In2O3 coreshell NRs exhibited a response of 22.43% at 50 °C, which was 5.11 times higher than that of pristine InN NRs.

Visualization of unstained homo/heterogeneous DNA nanostructures by low-voltage scanning transmission electron microscopy.

Three-dimensional (3D) homo/heterogeneous DNA nanostructures were studied with low-voltage scanning transmission electron microscopy (LV-STEM). Four types of 3D DNA nanostructures were designed and fabricated by the origami method including newly proposed protocols. The low-energy electron probe and optimized dark-field STEM detector enabled individual unstained DNA nanostructures to be clearly imaged by the single acquisition without the averaging process. For the vertically stacked double structures, assembled through modified single-stranded domains, and the structures containing a square opening (i.e., a hole) in the center, the LV-STEM successfully reveals the vertical information of these 3D structures as the contrast differences compared to the reference. For the heterogeneous structures, the LV-STEM visualized both regions of the functionalized gold nanoparticles and the DNA base structure with distinct contrasts. This study introduces a straightforward method to fabricate stackable DNA nanostructures or nanoparticles by replacing a relatively small number of incumbent DNA strands, which could realize the simple and sophisticated fabrication of higher-order 3D DNA homo/hetero nanostructures. Together with these design techniques of DNA nanostructures, this study has demonstrated that the LV-STEM is the swift and simple method for visualizing the 3D DNA nanostructures and certifying the fabricated products as the specified design, which is applicable to various research fields on soft materials including DNA nanotechnology.

Pravastatin Alleviates Radiation Proctitis by Regulating Thrombomodulin in Irradiated Endothelial Cells.

Although radiotherapy plays a crucial in the management of pelvic tumors, its toxicity on surrounding healthy tissues such as the small intestine, colon, and rectum is one of the major limitations associated with its use. In particular, proctitis is a major clinical complication of pelvic radiotherapy. Recent evidence suggests that endothelial injury significantly affects the initiation of radiation-induced inflammation. The damaged endothelial cells accelerate immune cell recruitment by activating the expression of endothelial adhesive molecules, which participate in the development of tissue damage. Pravastatin, a cholesterol lowering drug, exerts persistent anti-inflammatory and anti-thrombotic effects on irradiated endothelial cells and inhibits the interaction of leukocytes and damaged endothelial cells. Here, we aimed to investigate the effects of pravastatin on radiation-induced endothelial damage in human umbilical vein endothelial cell and a murine proctitis model. Pravastatin attenuated epithelial damage and inflammatory response in irradiated colorectal lesions. In particular, pravastatin improved radiation-induced endothelial damage by regulating thrombomodulin (TM) expression. In addition, exogenous TM inhibited leukocyte adhesion to the irradiated endothelial cells. Thus, pravastatin can inhibit endothelial damage by inducing TM, thereby alleviating radiation proctitis. Therefore, we suggest that pharmacological modulation of endothelial TM may limit intestinal inflammation after irradiation.

Formation of arsenic clusters in InAs nanowires with an Al2O3 shell.

An in-depth understanding of thermal behavior and phase evolution is required to apply heterostructured nanowires (NWs) in real devices. The intermediate status during the vaporization process of InAs NWs in an Al2O3 shell was studied by conducting quenching during in situ heating experiments, using a transmission electron microscope. The formation of As clusters in the amorphous Al2O3 shell was confirmed by analyzing the high-angle annular dark field images and energy-dispersive X-ray spectra. The As clusters existed independently in the shell and were also observed at the end of the InAs pieces obtained after quenching. The formation process of the As clusters was demonstrated from a theoretical perspective. Moreover, an ab initio molecular dynamics simulation (AIMD) was conducted to study the atomic and molecular behaviors.

Inhibition of Y Box Binding Protein 1 Suppresses Cell Growth and Motility in Colorectal Cancer.

Although chemo- or radiotherapy is usually performed in patients with colorectal cancer, the response is highly variable in locally rectal cancer. Therefore, additional studies are needed on predictable markers and the molecular mechanisms of chemo- and radiotherapy. Y box binding protein 1 (YB1) is an oncoprotein that is aberrantly expressed in many cancers, including colorectal cancer. However, to date there are no targeting agents or strategies to inhibit YB1 expression. Here, we investigate the oncogenic function of YB1 in colorectal cancer and methods to control its expression. We observed that YB1 expression level is correlated with colorectal cancer survival rate. Moreover, YB1 overexpression was associated with colorectal cancer lymph node metastasis and invasion. We also found that radiation exposure increased YB1 expression, which led to radioresistant colorectal cancer, mediated through the activation of cancer stem cell marker CD44 and PI3K/AKT/mTOR signaling. This study revealed, by both in vitro and in vivo assays, that depletion of YB1 could reduce cell proliferation and motility in colorectal cancer. We further demonstrated that the PI3K/mTOR inhibitor BEZ235 suppressed YB1 expression and enhanced the cytotoxicity of radiation. In addition, combined treatment with BEZ235 and radiation showed a significant antitumor response in an in vivo mouse xenograft model. Taken together, our results provide evidence that the activation of YB1 is a major factor in radioresistance and suggest that targeting YB1-mediated signaling is a promising therapeutic strategy for colorectal cancer.

Lubricant-Added Conductive Composite for Direct Writing of a Stretchable Electrode.

Stretchable electrodes, which are essential components of next-generation electronic devices, should be highly conductive under multiaxial tensile strain, durable under repetitive stretching, and patternable for integrating stretchable devices. Herein, a lubricant-added stretchable conductive composite of a polydimethylsiloxane-based elastomer containing silver flakes is reported. The added lubricant minimizes changes in conductivity during stretching and maximizes elastic durability by reducing friction. The conductivity varies from 1933.3 S·cm-1 at 0% strain to 307.5 S·cm-1 at 300% uniaxial stretching and 1264.1 S·cm-1 at 50% biaxial stretching. Furthermore, the composite exhibits high durability, even after 1000 cycles of stretching at 200%, and the conductive composite paste can be applied to fine-linewidth direct writing.