Self-doping effect in confined copper selenide semiconducting quantum dots for efficient photoelectrocatalytic oxygen evolution

Self-doping can not only suppress the photogenerated charge recombination of semiconducting quantum dots by self-introducing trapping states within the bandgap, but also provide high-density catalytic active sites as the consequence of abundant non-saturated bonds associated with the defects. Here, we successfully prepared semiconducting copper selenide (CuSe) confined quantum dots with abundant vacancies and systematically investigated their photoelectrochemical characteristics. Photoluminescence characterizations reveal that the presence of vacancies reduces the emission intensity dramatically, indicating a low recombination rate of photogenerated charge carriers due to the self-introduced trapping states within the bandgap. In addition, the ultra-low charge transfer resistance measured by electrochemical impedance spectroscopy implies the efficient charge transfer of CuSe semiconducting quantum dots-based photoelectrocatalysts, which is guaranteed by the high conductivity of their confined structure as revealed by room-temperature electrical transport measurements. Such high conductivity and low photogenerated charge carriers recombination rate, combined with high-density active sites and confined structure, guaranteeing the remarkable photoelectrocatalytic performance and stability as manifested by photoelectrocatalysis characterizations. This work promotes the development of semiconducting quantum dots-based photoelectrocatalysis and demonstrates CuSe semiconducting quantum confined catalysts as an advanced photoelectrocatalysts for oxygen evolution reaction

Design and optimization of Frequency Selective Surfaces (FSS)

The analysis method for Frequency Selective Surfaces (FSS), the spectral-domain Method of Moments (MoM) is improved to be applicable to normal incidence. A more efficient optimization algorithm, Differential Evolution Strategy (DES) is proposed to optimize the standard, non-irregular FSS unit-cell and dielectric properties. DES coupled with spectral-domain MoM is proposed to design arbitrary FSS structures especially with multi-layered hexagon and gangbuster array. DES combined with Equivalent Circuit Model (ECM) is proposed to design double-square, gridded-square and gridded-double-square array for multi-band application. The DES is applied to optimize the dimensions and dielectric properties of FSS dipole array. The frequency response of FSS screen is analyzed by employing spectral-domain MoM or ECM technique. The tedious trial and error procedure is avoided.DOCTOR OF PHILOSOPHY (EEE

Terahertz metamaterial absorber with switchable function between broadband and dual narrowband

In this paper, based on the tunability of vanadium dioxide and graphene, a simple and novel multifunctional terahertz metamaterial absorber is proposed that can dynamically switch functions and absorption spectra. The simulation results using the finite element method via Comsol Multiphysics show that the proposed design can achieve large broadband absorption, perfect dual narrowband absorption, and total reflection through controlling external conditions. The absorption intensity can be adjusted from 4.5% to 100% over the whole broadband operation range. A detailed absorption mechanism explanation is given with the help of impedance matching principles and the distribution of current and electric field, and the influence of graphene’s Fermi level and different incidence angles on absorption performance is evaluated. Our design not only functionally adds the part to be a reflector but also provides considerable improvements in absorption amplitude, bandwidth, and adjustment range when compared to previous works. In addition, its function switching and resonant frequencies are flexible in terms of tuning and have strong resistance to external temperature interference. Therefore, the proposed structure holds significant applications in the terahertz field, such as terahertz modulators, sensing, and optical switches

Matrix-dependent Strain Distributions of Au and Ag Nanoparticles in a Metal-oxide-semiconductor-based Nonvolatile Memory Device

The matrix-dependent strain distributions of Au and Ag nanoparticles in a metal-oxide-semiconductor based nonvolatile memory device are investigated by finite element calculations. The simulation results clearly indicate that both Au and Ag nanoparticles incur compressive strain by high-k Al2O3 and conventional SiO2 dielectrics. The strain distribution of nanoparticles is closely related to the surrounding matrix. Nanoparticles embedded in different matrices experience different compressive stresses, which provide opportunities for tailoring the microstructure of Au and Ag nanoparticles. This opens up ways for exploring strain effects on physical properties and further tunes the charge storage properties of nanoparticles

Uniformity Investigation in 3C-SiC Epitaxial Layers Grown on Si Substrates by Horizontal Hot-Wall CVD

50mm 3C-SiC epilayers are grown on （100） and （111） Si substrates in a newly developed horizontal lowpressure hot-wall CVD reactor under different growth pressures and flow rates of H_2 carrier gas. The structure,electrical properties, and thickness uniformity of the 3C-SiC epilayers are investigated by X-ray diffraction （XRD） ,sheet resistance measurement, and spectroscopic ellipsometry. XRD patterns show that the 3C-SiC films have excellent crystallinity. The narrowest full widths at half maximum of the SIC（200） and （111） peaks are 0.41° and 0.21°, respectively. The best electrical uniformity of the 50mm 3C-SiC films obtained by sheet resistance measurement is 2.15%. A σ/mean value of ± 5.7% in thickness uniformity is obtained

An Ultra-Low Bending Loss Negative Curvature Hollow Core Fiber With a Polygon Jacketing Layer

We design and simulate a new type of hollow-core antiresonant fiber with the polygon jacketing layer. Through numerical calculations, the confinement loss is approximately 0.003 dB/km at 1.45 μm and the bandwidth is ∼ 410 nm @ CL < 0.1 dB/km. We found that more nested tubes can be connected to the jacketing layer to avoid the generation of more cladding nodes. The nested tube cladding with the small size of air holes can effectively suppress the coupling between the fiber cladding and core modes even at extreme bending conditions. Ultra-low bending loss is achieved, and the bending loss is lower than ∼ 0.05 dB/km @ bend radius Rb = 3 cm at 1.50 μm

Alternating Magnetic Field Induced Magnetic Heating in Ferromagnetic Cobalt Single-Atom Catalysts for Efficient Oxygen Evolution Reaction

Alternating magnetic field (AMF) is a promising methodology for further improving magnetic single-atom catalyst (SAC) activity toward oxygen evolution reaction (OER). Herein, the anchoring of Co single atoms on MoS2 support (Co@MoS2), leading to the appearance of in-plane room-temperature ferromagnetic properties, is favorable for the parallel spin arrangement of oxygen atoms when a magnetic field is applied. Moreover, field-assisted electrocatalytic experiments confirmed that the spin direction of Co@MoS2 is changing with the applied magnetic field. On this basis, under AMF, the active sites in ferromagnetic Co@MoS2 were heated by exploiting the magnetic heating generated from spin polarization flip of these SACs to further expedite OER efficiency, with overpotential at 10 mA cm–2 reduced from 317 mV to 250 mV. This work introduces a feasible and efficient approach to enhance the OER performance of Co@MoS2 by AMF, shedding some light on the further development of magnetic SACs for energy conversion

Construction of a Prognostic Gene Signature Associated with Immune Infiltration in Glioma: A Comprehensive Analysis Based on the CGGA

Background. Tumor microenvironment (TME) is closely related to the progression of glioma and the therapeutic effect of drugs on this cancer. The aim of this study was to develop a signature associated with the tumor immune microenvironment using machine learning. Methods. We downloaded the transcriptomic and clinical data of glioma patients from the Chinese Glioma Genome Atlas (CGGA) databases (mRNAseq_693). The single-sample Gene Set Enrichment Analysis (ssGSEA) database was used to quantify the relative abundance of immune cells. We divided patients into two different infiltration groups via unsupervised clustering analysis of immune cells and then selected differentially expressed genes (DEGs) between the two groups. Survival-related genes were determined using Cox regression analysis. We next randomly divided patients into a training set and a testing set at a ratio of 7 : 3. By integrating the DEGs into least absolute shrinkage and selection operator (LASSO) regression analysis in the training set, we were able to construct a 15-gene signature, which was validated in the testing and total sets. We further validated the signature in the mRNAseq_325 dataset of CGGA. Results. We identified 74 DEGs associated with tumor immune infiltration, 70 of which were significantly associated with overall survival (OS). An immune-related gene signature was established, consisting of 15 key genes: adenosine triphosphate (ATP)-binding cassette subfamily C member 3 (ABCC3), collagen type IV alpha 1 chain (COL4A1), podoplanin (PDPN), annexin A1 (ANXA1), COL4A2, insulin-like growth factor binding protein 2 (IGFBP2), serpin family A member 3 (SERPINA3), CXXC-type zinc finger protein 11 (CXXC11), junctophilin 3 (JPH3), secretogranin III (SCG3), secreted protein acidic and rich in cysteine (SPARC)-related modular calcium-binding protein 1 (SMOC1), Cluster of Differentiation 14 (CD14), COL1A1, S100 calcium-binding protein A4 (S100A4), and transforming growth factor beta 1 (TGF-β1). The OS of patients in the high-risk group was worse than that of patients in the low-risk group. GSEA showed that interleukin-6 (IL-6)/Janus kinase (JAK)/signal transducer and activator of transcription (STAT3) signaling, interferon gamma (IFN-γ) response, angiogenesis, and coagulation were more highly enriched in the high-risk group and that oxidative phosphorylation was more highly enriched in the low-risk group. Conclusion. We constructed a stable gene signature associated with immune infiltration to predict the survival rates of glioma patients

Supplementation of Lactobacillus plantarum ATCC14917 mitigates non-alcoholic fatty liver disease in high-fat-diet-fed rats

Atherosclerosis and non-alcoholic fatty liver disease (NAFLD) have been increasing at an alarming rate worldwide. Many clinical studies have underlined the link between NAFLD and atherosclerosis. Our previous experiments have discovered that Lactobacillus (L.) plantarum ATCC14917 supplementation could decrease the progression of atherosclerotic lesion formation. In this study, we aimed to investigate the role of supplementation of L. plantarum ATCC14917 mitigates liver injury in rats fed with a high-fat diet (HFD, 45% kcal from fat). A total of 32 rats were randomly divided into four groups, including two intervention groups, who fed with HFD and administering either 1 × 107 or 1 × 109 colony forming units (CFU) of L. plantarum ATCC14917, the normal control group, and the HFD control group. The results showed that supplementation with low-dose and high-dose of L. plantarum ATCC14917 for 8 weeks could alleviate the body weight gain (p < 0.05), hepatic steatosis, and serum lipid metabolism (p < 0.05) in HFD-fed rats. Moreover, supplementation of L. plantarum ATCC 14917 decreased total cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels (p < 0.05) in serum, and improved HFD-associated inflammation (p < 0.05). Furthermore, cecal contents were analyzed by high-throughput 16S ribosomal RNA sequencing. The results indicated that supplementation of L. plantarum ATCC 14917 could ameliorate HFD-induced gut dysbiosis. In summary, our findings suggest that supplementation of L. plantarum ATCC 14917 could mitigate NAFLD in rats, suggesting it may be considered as a probiotic agent for preventing HFD-induced obesity

Interfacial Effect on Photo-Modulated Magnetic Properties of Core/Shell-Structured NiFe/NiFe2O4 Nanoparticles

Photo-modulated magnetism has become an emerging method for technological applications, such as magneto-optical devices. In this work, by introducing oxygen during rapid thermal annealing, NiFe/NiFe2O4 core/shell nanoparticles were successfully fabricated by pulsed laser deposition. Obvious photo-modulated ferromagnetism was observed in core/shell nanoparticles confined in Al2O3 film. Theoretical and experimental investigations indicate much more photogenerated electrons are captured at the interface of NiFe/NiFe2O4 compared with NiFe nanoparticles due to interfacial effect, resulting in the improved ferromagnetism under light irradiation. This work provides a promising strategy for optical engineering design of optical information storage, high-speed wireless communication, and magneto-optical semiconductor devices