Bulk SrTiO3 is a well‐known band insulator and the most common substrate used in the field of complex oxide heterostructures. Its surface and interface with other oxides, however, have demonstrated a ...variety of remarkable behaviors distinct from those expected. In this work, using a suite of in situ techniques to monitor both the atomic and electronic structures of the SrTiO3 (001) surface prior to and during growth, the disappearance and re‐appearance of a 2D electron gas (2DEG) is observed after the completion of each SrO and TiO2 monolayer, respectively. The 2DEG is identified with the TiO2 double layer present at the initial SrTiO3 surface, which gives rise to a surface potential and mobile electrons due to vacancies within the TiO2−x adlayer. Much like the electronic reconstruction discovered in other systems, two atomic planes are required, here supplied by the double layer. The combined in situ scattering/spectroscopy findings resolve a number of longstanding issues associated with complex oxide interfaces, facilitating the employment of atomic‐scale defect engineering in oxide electronics.
The 2D electron gas at the surface of SrTiO3 (001) can be turned on and off by depositing either SrO or TiO2, which is observed by a combination of oxide molecular beam epitaxy with in situ synchrotron X‐ray scattering and angle‐resolved photoemission spectroscopy. Either way, the surface remains TiO2‐terminated.
Controlling material properties at the nanoscale is a critical enabler of high performance electronic and photonic devices. A prototypical material example is VO2, where a structural phase transition ...in correlation with dramatic changes in resistivity, optical response, and thermal properties demonstrates particular technological importance. While the phase transition in VO2 can be controlled at macroscopic scales, reliable and reversible nanoscale control of the material phases has remained elusive. Here, reconfigurable nanoscale manipulations of VO2 from the pristine monoclinic semiconducting phase to either a stable monoclinic metallic phase, a metastable rutile metallic phase, or a layered insulating phase using an atomic force microscope is demonstrated at room temperature. The capability to directly write and erase arbitrary 2D patterns of different material phases with distinct optical and electrical properties builds a solid foundation for future reprogrammable multifunctional device engineering.
Reconfigurable nanoscale manipulations of VO2 from the pristine monoclinic semiconducting phase to either a stable monoclinic metallic phase, a metastable rutile metallic phase, or a layered insulating phase using an atomic force microscope are demonstrated. The direct writing of different material phases with distinct optical/electrical properties opens up new opportunities for building integrated nanoelectronics on monolithic correlated oxide platforms.
High‐grade neuroendocrine tumors (NETs) of the lung consist of small‐cell lung cancer (SCLC) and large‐cell neuroendocrine carcinoma (LCNEC). Both exhibit aggressive malignancy with poor prognosis. ...The transformation of lung adenocarcinoma (ADC) to SCLC or LCNEC also contributes to acquired resistance to epidermal growth factor receptor (EGFR)‐tyrosine kinase inhibitors (TKIs). Despite initially being responsive to chemotherapy, high‐grade NET patients inevitably develop drug resistance; thus, novel therapeutic targets are urgently needed for these patients. Our study reported that VGF (nerve growth factor inducible), a factor mainly expressed in neurons during neural development, is highly expressed in SCLC and LCNEC as well as in a subset of ADCs, whereas targeting VGF attenuates cancer cell growth and tumor formation. High VGF expression was associated with advanced stage SCLC and predicted poor prognosis in lung ADC. In addition, EGFR‐TKI selection enriched VGF expression in TKI‐resistant ADC under epigenetic control. The VGF locus possessed the HDAC1 binding site, and treatment of ADC cells with the HDAC1 inhibitor induced VGF expression. High VGF expression was associated with chemoresistance, and silencing VGF induced BMF and BCL2L11 expression and rendered lung cancer cells sensitive to chemotherapy drugs. These findings suggested the potential of VGF as a prognostic factor and therapeutic target in lung cancers with neuroendocrine feature.
What's new?
Neuronal survival factor VGF is highly expressed in neuroendocrine tissues. However, its biological and clinical significance in lung neuroendocrine tumors is elusive. Our study shows that high VGF expression in neuroendocrine tumors prevents cancer cell apoptosis. VGF is regulated by HDAC1‐mediated epigenetic control in lung adenocarcinoma, and silencing VGF decreases tumor growth through enhanced cancer cell apoptosis. High VGF expression leads to resistance to chemotherapy drugs, including epidermal growth factor receptor‐tyrosine kinase inhibitors, and predicts poor survival in lung cancer patients. The findings indicate the potential of VGF as a theranostic factor in lung cancer.
The purpose of this study is to explore, after the epidemic, the intelligent traffic management system, which is the key to creating a green leisure tourism environment in the move towards ...sustainable urban development. First, quantitative research, snowballing, and convenience sampling methods are used to analyze 750 questionnaires with a basic statistical test, t-test, ANOVA test, and the Pearson product–moment correlation coefficient (PPMCC) method. Qualitative research and a semi-structured interview method are used to collect the opinions of six experts on the data results. Finally, the results are discussed with the multivariate inspection method. Although the current electric bicycle system is convenient, the study found that the service quality of the airport is sufficient; that the fare of the subway is low and popular with students if the system can ease the crowd during peak hours; and that the login and security check time can be shortened, which can help improve the operating convenience of the system interface and link the information of leisure and tourism activities. On the other hand, adjusting fares, increasing seats, planning for women-only ticketing measures and travel space, providing disinfection or cleaning facilities in public areas, and improving passenger’s public health literacy and epidemic prevention cooperation will further enhance the student travel experience, improve the smart city and green tourism network, and help achieve sustainable urban tourism.
Complex systems, which consist of a large number of interacting constituents, often exhibit universal behavior near a phase transition. A slowdown of certain dynamical observables is one such ...recurring feature found in a vast array of contexts. This phenomenon, known as critical slowing-down, is well studied mostly in thermodynamic phase transitions. However, it is less understood in highly nonequilibrium settings, where the time it takes to traverse the phase boundary becomes comparable to the timescale of dynamical fluctuations. Using transient optical spectroscopy and femtosecond electron diffraction, we studied a photoinduced transition of a model charge-density-wave (CDW) compound LaTe3. We observed that it takes the longest time to suppress the order parameter at the threshold photoexcitation density, where the CDW transiently vanishes. This finding can be captured by generalizing the time-dependent Landau theory to a system far from equilibrium. The experimental observation and theoretical understanding of dynamical slowing-down may offer insight into other general principles behind nonequilibrium phase transitions in many-body systems.
Greenhouse gases, such as carbon dioxide, have a great impact on global warming and climate change. CO2 trapping and reduction have been one of the solutions to slow down the temperature rise. Copper ...has proven to be an effective electrocatalyst to transform CO2 into useful organic compounds, such as CH4, C2H4, and HCOOH. Here, nanoporous copper (NPC), that are synthesized from various precursor phases of Cu–Al alloys, like pure Al solid solution α, CuAl2 θ and CuAl η phases, with different relative densities and ligament sizes are being used as electrocatalyst for CO2 reduction reaction (CO2RR). The ligament sizes of the NPCs can be adjusted with the use of dealloying solution, either in HCl or NaOH, and dealloying temperatures. In this study, the ligament sizes were available from the range of 51–116 nm. A hierarchical structure containing a lamellar eutectic structure with an interlayer spacing of 6 μm in the parent phases is observed from NPC synthesized from Cu18Al82. The results show that the current density of CO2RR using NPC as electrocatalyst is 2–5 times higher than that of using copper foil. The ligament size effect is more obvious than the relative density effect since the peak current density was obtained from the NPC with ligament size of 76 nm. The product distribution suggested that NPC with hierarchical structure has higher Faraday efficiency of ethylene than conventional NPC or Cu foil at high overpotential.
•Synthesis of hierarchical nanoporous copper in eutectic CuAl alloys.•With the use of nanoporous copper as an electrocatalyst, the reaction rate is 5 times higher than copper foil.•Hierarchical nanoporous copper has higher Faraday efficiency than conventional NPC or Cu foil at high overpotential.
Bulk SrTiO
is a well-known band insulator and the most common substrate used in the field of complex oxide heterostructures. Its surface and interface with other oxides, however, have demonstrated a ...variety of remarkable behaviors distinct from those expected. In this work, using a suite of in situ techniques to monitor both the atomic and electronic structures of the SrTiO
(001) surface prior to and during growth, the disappearance and re-appearance of a 2D electron gas (2DEG) is observed after the completion of each SrO and TiO
monolayer, respectively. The 2DEG is identified with the TiO
double layer present at the initial SrTiO
surface, which gives rise to a surface potential and mobile electrons due to vacancies within the TiO
adlayer. Much like the electronic reconstruction discovered in other systems, two atomic planes are required, here supplied by the double layer. The combined in situ scattering/spectroscopy findings resolve a number of longstanding issues associated with complex oxide interfaces, facilitating the employment of atomic-scale defect engineering in oxide electronics.
No half-time for COVID-19 Lin, I-Cheng; Chen, Fang-Hao; Lee, Hsin-Chien ...
Journal of the Formosan Medical Association,
01/2022, Volume:
121, Issue:
1
Journal Article
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