We have developed a one-step, hydrofluoric acid-free hydrothermal etching method that not only produces bismuth nano/micrometer-sized spheres but also prepares porous silicon with vertical holes. By controlling the heating temperature and time, nanoscale vertical-channeled porous silicon can be received. Our result indicated that the Bi clusters were formed first on the wafer surface. Then the etching of the Bi to the wafer creates the holes. Later, the Bi spheres went into the holes and expedited the etching process. A formation mechanism and chemical process have been proposed on the basis of experimental data. This simple chemistry approach may be of great scientific and technological importance for preparing porous silicon wafer.
Abstract Transition and rare earth metal elements have played a vital role in synthesis of functional and smart materials because of their unique electronic structures and mixed valences. Experimental measurement of the valence states is thus important for understanding the mechanism which drives the functional properties. Lai1.xSrxCoO3-y(LSCO), for example, is an ionic conductor with potential applications in fuel cells and many other fields. In this type of materials, the anion deficiency is directly associated with the ratio of Co2+/Co3+ (or Co3+/Co4+) present in the specimen. It is known that the anion deficiency of the material depends on the operation temperature, but a direct measurement of anion deficiency is a challenge to existing microscopy techniques. In this paper, we present the in-situ analysis of Co valence in LSCO using electron energy-loss spectroscopy (EELS) in a transmission electron microscope. LSCO thin films (with x = 0.5) were grown on polished MgO(00l) substrate by liquid source metal-organic chemical vapor deposition (MOCVD) method [1].
Path planning plays an essential role in many fields such as autonomous navigation, robot obstacle avoidance, and route optimization. Despite Hybrid A* being able to handle non-holonomic constraints and generating smoother paths than classical A*, it still suffers from computational efficiency issues, especially in relatively simple environments. By modifying parameters, this paper proposes an Improved Hybrid A* algorithm, which, while maintaining the kinematic feasibility of Hybrid A*, reduces the analytic expansion intervals, interpolation distances, and costs of switching direction. These parameters are tuned towards the reduction of reliance on heuristics and faster computation in relatively simple maze environments. The experimental results in maze environments with varying complexities demonstrate that, compared to the traditional Hybrid A* algorithm, the proposed Improved Hybrid A* algorithm can significantly enhance computing efficiency, particularly in less complex environments. This has shown that the morphology approach improves performance and is thus more suitable for autonomous navigation, where computational efficiency is important.
To realize the sustainable energy supply in a smart city, it is essential to maximize energy scavenging from the city environments for achieving the self-powered functions of some intelligent devices and sensors. Although the solar energy can be well harvested by using existing technologies, the large amounts of wasted wind energy in the city cannot be effectively utilized since conventional wind turbine generators can only be installed in remote areas due to their large volumes and safety issues. Here, we rationally design a hybridized nanogenerator, including a solar cell (SC) and a triboelectric nanogenerator (TENG), that can individually/simultaneously scavenge solar and wind energies, which can be extensively installed on the roofs of the city buildings. Under the same device area of about 120 mm × 22 mm, the SC can deliver a largest output power of about 8 mW, while the output power of the TENG can be up to 26 mW. Impedance matching between the SC and TENG has been achieved by using a transformer to decrease the impedance of the TENG. The hybridized nanogenerator has a larger output current and a better charging performance than that of the individual SC or TENG. This research presents a feasible approach to maximize solar and wind energies scavenging from the city environments with the aim to realize some self-powered functions in smart city.
A multislice theory is proposed to solve Yoshioka's coupling equations for elastic and inelastic scattered high-energy electrons in a solid. This method is capable, in principle, of including the non-periodic crystal structures and the electron multiple scattering among all the excited states in the calculations. It is proved that the proposed theory for calculating the energy-filtered inelastic images [Wang (1989). Acta Cryst. A45, 193-199], based on the physical optics approach, is equivalent to the quantum-mechanical theory under some approximations. The basic theory of simulating the energy-filtered inelastic image of core-shell losses and thermal diffuse scattering is outlined.
Breast cancer is notorious for its increasing incidence for decades. Ascending evidence has demonstrated that translocase of inner mitochondrial membrane (TIMM) proteins play vital roles in progression of several types of human cancer. However, the biological behaviors and molecular mechanisms of TIMM8A in breast cancer remain not fully illustrated.Pan-cancer analysis was firstly performed for TIMM8A's expression and prognosis by Oncomine database. Subsequently, TIMM8A-related noncoding RNAs (ncRNAs) were identified by a series of bioinformatics analyses and dual-luciferase reporter assay, including expression analysis, correlation analysis, and survival analysis. Moreover, the effect of TIMM8A on breast cancer proliferation and apoptosis was evaluated in vitro by CCK-8 assays, EdU cell proliferation assays, JC-1 mitochondrial membrane potential detection assays and Western blot assays and the in vivo effect was revealed through a patient-derived xenograft mouse model.We found that TIMM8A showed higher expression level in breast cancer and the higher TIMM8A mRNA expression group had a poorer prognosis than the lower TIMM8A group. hsa-circ-0107314/hsa-circ-0021867/hsa-circ-0122013 might be the three most potential upstream circRNAs of hsa-miR-34c-5p/hsa-miR-449a-TIMM8A axis in breast cancer. TIMM8A promotes proliferation of breast cancer cells in vitro and tumor growth in vivo.Our results confirmed that ncRNAs-mediated upregulation of TIMM8A correlated with poor prognosis and act as an oncogene in breast cancer.
Collecting and converting energy from ambient air flow promise to be a viable approach in developing self-powered autonomous electronics. Here, we report an effective and robust triboelectric generator that consists of an undulating thin-film membrane and an array of segmented fine-sized electrode pairs on a single substrate. Sequential processes of contact electrification and electrostatic induction generate alternating flows of free electrons when the membrane interacts with ambient air flow. Based on an optimum rational design, the segmented electrodes play an essential role in boosting the output current, leading to an enhancement of over 500% compared to the structure without the segmentation. The thin-film based generator can simultaneously and continuously light up tens of commercial light-emitting diodes. Moreover, it possesses exceptional durability, providing constant electric output after millions of operation cycles. This work offers a truly practical solution that opens the avenue to take advantage of wind energy by using the triboelectric effect.
By coating one side of the surface of a ZnO nanobelt (NB) with multilayer polymers using an electrostatic self-assembling process, a humidity/chemical nanosensor based on piezoelectric field effect transistor (PE-FET) is demonstrated. The working principle of the PE-FET relies on the self-contraction/expansion of the polymer, which builds up a strain in the piezoelectric NB and induces a potential drop across the NB that serves as the gate voltage for controlling the current flowing through the NB. The response of PE-FET to the phase transition of the coating polymer was also demonstrated. The device is a component for nanopiezotronics.
