Silicon carbide single crystals for high-temperature supercapacitors.

Designing advanced electrode materials that can be reliably cycled at high temperatures and used for assembling advanced energy storage devices remain a major challenge. As a representative of novel wide bandgap semiconductors, silicon carbide (SiC) single crystals have broad prospects in high-temperature energy storage due to their excellent characteristics such as low thermal expansion coefficient, high temperature radiation resistance and stable chemical properties. In this work, an N-type SiC single-crystal material with a high-density porous structure was successfully designed and prepared by using an improved electrochemical anodic oxidation strategy. Besides, the N-type SiC single crystals were used in electrochemical energy storage as an integrated electrode material, exhibiting superior electrochemical performance. In addition, the high-temperature supercapacitor device assembled with ionic liquids has a wide operating temperature range and maintains a capacity of 88.24% after 5000 cycles at 150 °C. The reasons for its high energy storage performance are discussed through electrochemical tests and first-principles calculation methods. This study proves that the application of SiC single crystals in supercapacitor devices has great potential in the field of high-temperature energy storage, providing a reference for the further development of novel semiconductors in the field of energy storage and optoelectronic devices.

Research progress of large size SiC single crystal materials and devices.

SiC semiconductor is the focus of recent international research. It is also an important raw material for China to achieve carbon emission peak and carbon neutrality. After nearly 20 years of research and development, we focus on the three types SiC crystals, n-type, p-type and semi-insulating, indicating the development of Shandong University for crystal growth. And defects control, electrical property, atomic polishing, and corresponding device authentication all obtain great progress. Total dislocation density of 6-inch n-type substrates decreases to 2307 cm-2, where BPD (Basal Plane Dislocation) lowers to 333 cm-2 and TSD (Threading Screw Dislocation) 19 cm-2. The full width at half maximum (FWHM) (0004) rocking curves is only 14.4 arcsec. The resistivity reaches more than 1E + 12 Ω·cm for semi-insulating SiC and lower than 20 mΩ·cm for n-type SiC. The impurity concentrations in 6-inch high-purity semi-insulating (HPSI) SiC crystals reach extreme low levels. The devices made of various substrate materials have good performance.

Pinning and Anharmonic Phonon Effect of Quasi-Free-Standing Bilayer Epitaxial Graphene on SiC.

Epitaxial graphene on SiC without substrate interaction is viewed as one of the most promising two-dimensional (2D) materials in the microelectronics field. In this study, quasi-free-standing bilayer epitaxial graphene (QFSBEG) on SiC was fabricated by H2 intercalation under different time periods, and the temperature-dependent Raman spectra were recorded to evaluate the intrinsic structural difference generated by H2 time duration. The G peak thermal lineshift rates dω/dT showed that the H2 intercalation significantly weakened the pinning effect in epitaxial graphene. Furthermore, the G peak dω/dT value showed a perspicuous pinning effect disparity of QFSBEG samples. Additionally, the anharmonic phonon effect was investigated from the Raman lineshift of peaks. The physical mechanism responsible for dominating the G-mode temperature-dependent behavior among samples with different substrate coupling effects was elucidated. The phonon decay process of different samples was compared as the temperature increased. The evolution from in situ grown graphene to QFSBEG was determined. This study will expand the understanding of QFSBEG and pave a new way for its fabrication.

Micropipes in SiC Single Crystal Observed by Molten KOH Etching.

Micropipe, a "killer" defect in SiC crystals, severely hampers the outstanding performance of SiC-based devices. In this paper, the etching behavior of micropipes in 4H-SiC and 6H-SiC wafers was studied using the molten KOH etching method. The spectra of 4H-SiC and 6H-SiC crystals containing micropipes were examined using Raman scattering. A new Raman peak accompanying micropipes located near -784 cm-1 was observed, which may have been induced by polymorphic transformation during the etching process in the area of micropipe etch pits. This feature may provide a new way to distinguish micropipes from other defects. In addition, the preferable etching conditions for distinguishing micropipes from threading screw dislocations (TSDs) was determined using laser confocal microscopy, scanning electron microscopy (SEM) and optical microscopy. Meanwhile, the micropipe etching pits were classified into two types based on their morphology and formation mechanism.

Basal Plane Bending of Homoepitaxial MPCVD Single-Crystal Diamond.

We report herein high-resolution X-ray diffraction measurements of basal plane bending of homoepitaxial single-crystal diamond (SCD). We define SCD (100) as the base plane. The results revealed that growth parameters such as temperature, growth time, and basal plane bending of the substrate all affect the basal plane bending of SCD. First, the basal plane bending of SCD depends mainly on the substrate and becomes severe with increasing basal plane bending of the substrate. The SCD growth experiments show that the basal plane bending increases with elevated growth temperature and increased growth time. Finally, to understand the mechanism, we investigated the substrate-surface temperature distribution as a function of basal plane bending of SCD fabricated by chemical vapor deposition (CVD). This allowed us to propose a model and understand the origin of basal plane bending. The results indicate that an uneven temperature distribution on the substrate surface is the main cause of the base-plane bending of CVD diamond.

Finite element analysis of fiber-optic Fabry-Perot pressure sensors based on silicon diaphragms.

Fiber-optic Fabry-Perot pressure sensors based on silicon diaphragms of different thicknesses were fabricated using surface and bulk MEMS techniques in this study. The multi-beam interference resulting from multiple reflecting mirrors with the elastic deformation of the Fabry-Perot sensor was simulated by finite element analysis. The pressure sensitivities of the sensors with different diaphragm thicknesses and the relationship between the pressure and the wavelength shift were simulated. The simulation results were in good agreement with the test results. This study provides guidance for future sensor models and parameter design.

Comparison of Measurements with Finite-Element Analysis of Silicon-Diaphragm-Based Fiber-Optic Fabry-Perot Temperature Sensors.

Silicon-diaphragm-based fiber-optic Fabry-Perot sensors with different intracavity pressures were fabricated by anodic bonding and microelectromechanical techniques. The thermal stress and thermal expansion of the Fabry-Perot (FP) sensor caused by high-temperature bonding and temperature change were simulated by finite-element analysis. The calculated thermal stress is largest in the center and edge regions of the resonance cavity, reaching from 2 to 6 MPa. The reflection spectra and temperature sensitivity of the sensors were simulated by using a two-dimensional wave-optic model in Comsol. Theoretical calculations were also made for the FP cavity without considering silicon-diaphragm deformation and thermal stress. Four sensors with intracavity pressures of 0.01, 0.03, 0.04, and 0.05 MPa were tested at low temperatures, showing a high degree of consistency with the simulation results rather than theoretical calculation, especially for high intracavity pressure. This method is expected to aid the analysis of thermal stress generated during the bonding process and to facilitate better design and control of the temperature sensitivity of the sensor.

Effects of All-Trans Retinoic Acid on Lipopolysaccharide-Induced Synovial Explant.

The present study was conducted to assess the effect of all-trans retinoic acid (ATRA) on synovial explants from rats with rheumatoid arthritis (RA) induced by lipopolysaccharides (LPS). In our study, synovial membranes were excised from the knees of healthy adult Wistar female rats under sterile conditions. We first investigated the synoviums incubated in a control medium or in a medium containing 10 µg/mL LPS, each for 24, 48, and 72 h (LPS-experiment). The changes in inflammatory response from the synoviums were observed at different culture times. Then, we assessed the synoviums exposed to different ATRA concentrations for 24 h (ATRA-experiment). The controls (blank, model group, and solvent groups) were set up. The effects of ATRA on synovitis were evaluated by measuring the production of cytokines, and nitric oxide (NO) and the expression of cartilage damage related proteases. In the LPS-experiment, LPS contributed to the release of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and matrix metalloproteinase-9 (MMP-9) in synovial explants. Importantly, LPS did not cause a significant pathological damage. The inflammatory response observed in this model was significant for 24 h, suggesting that LPS-induced synovial explants were successfully established. In the ATRA-experiment, ATRA suppressed the expression of IL-6, TNF-α, NO, a disintegrin and metalloprotease with thrombospondin motifs-4 (ADAMTS-4), MMP-3, and MMP-9. Taken together, ATRA exhibited inhibitory effects on LPS-induced synovial immune inflammatory response stimulated by the regulation of inflammatory mediators and cartilage damage related proteases in synovial explants, demonstrating a potential protective effect on synovitis and joint destruction in the patients with RA.

[Effects of Genistein on Whole Genome Expression Profiles of Mice Testes Tissue Cultured in vitro].

OBJECTIVE: To investigate the effects of Genistein (Gen) on the whole expression profiles of testes in mice by using the gene chip technology,and analyze the mechanism how Gen exerts testis on gene level. METHODS: The testicular tissues of suckling mice were cultured in vitro,and separated into control group and Gen group with the dose of 5 µmol/L. After 72 h of culture,we extracted the total RNA and purified it,then detected the gene expression by using Agilent gene array. RESULTS: Compared with the control,there were 84 genes expressed differently in Gen group,including 47 upregulated genes and 37 downregulated genes. We classified these genes as 14 categories in Gen group by GO ( P<0.05),including cell proliferation,cell death,the immune system and reproductive development. CONCLUSION: The whole gene chip test found that Gen can mainly affect the functions of testes by regulating the expression of gene related to cell development,proliferation and cell cycle function, which can influence the spermatogenesis and change the testis cell proliferation and apoptosis.

[The Effects of All-trans Retinoic Acid on the Expression of Inflammatory Cytokines and Cartilage Damage Related Protease in Rats with Collagen Induced Arthritis].

OBJECTIVES: To investigate the effects of all-trans retinoic acid (ATRA) on arthritis and the expressions of inflammatory cytokines and cartilage damage related proteases of the collagen-induced arthritis model (CIA) rats in vivo. METHODS: The CIA model of rheumatoid arthritis was induced with C2 and incomplete Freund's adjuvant. The rats were randomly divided into control group, CIA model group and two ATRA dose groups (ATRA 0.50 mg/kg group and ATRA 1.00 mg/kg group). ATRA were given three times per week for six weeks in ATRA groups. Morphological changes, arthritis index (AI) scores, the semi-quantitative scores of pathology damage, the protein expressions of cartilage damage related proteases and the serum levels of TNF-α, IL-17A, IFN-γ, IL-4, IL-10 were observed. RESULTS: The AI scores of ATRA groups were similar to CIA model group ( P<0.05). Apparent morphological disorders in knee and ankle joints were observed in the CIA model group and ATRA 1.00 mg/kg group. The structure of knee joint was improved slightly in ATRA 0.50 mg/kg group. The serum levels of TNF-α, IFN-γ and IL-17A were decreased in both ATRA groups; ATRA also can increase the serum level of IL-4. Compared to CIA model group, the protein expressions of ADAMTS-4, MMP3, MMP1 were decreased in both ATRA groups ( P<0.05). CONCLUSIONS: ATRA, which was able to inhibit pro-inflammatory cytokines secretion, could correct the imbalance of Th1/Th2 and Th17/Treg. ATRA also can reduce the expressions of cartilage damage related proteases, which proved that ATRA may have a beneficial effect on rheumatoid arthritis.

[Prophylactic administration of all-trans retinoic acid alleviates inflammation in rats with collagen-induced arthritis].

OBJECTIVE: To investigate the effects of prophylactic administration of all-trans retinoic acid (ATRA) in relieving inflammation in a rat model of collagen-induced arthritis (CIA). METHODS: Female Wistar rats (6 to 8 weeks old) were randomly divided into normal control group, solvent control group, and prophylactic ATRA treatment (0.05, 0.5, and 5 mg/kg) groups. All the rats except for those in normal control group were subjected to subcutaneous injection of type II collagen and incomplete Freund adjuvant in the tails to induce CIA, followed by injection on the following day with saline, corn oil or different doses of ATRA 3 times a week. The arthritis index (AI) scores, histological scores, serum levels of TNF-α, IL-17A, and IL-10, and expressions of proteases related with cartilage damage were evaluated. RESULTS: On the 15th day after the primary immunization, the AI scores increased significantly in all but the normal control groups; the scores increased progressively in all the 3 ATRA groups but remained lower than that in the solvent control group, which was stable over time. The rats in the 3 ATRA groups showed obvious pathologies in the knee and ankle joints, but the semi-quantitative scores of pathology damage showed no significance among them. Compared with those in solvent control group, the serum IL-17A and TNF-α levels decreased, serum IL-10 level increased, and the expressions of ADAMT-4 and MMP-3 proteins decreased significantly in the knees in the 3 ATRA groups. CONCLUSION: ATRA can reduce the production of TNF-α and IL-17A and increase the production of IL-10 to alleviate the inflammation in rats with CIA. ATRA may delay the progression of RA by correcting the imbalance of Th1/Th2 and Th17/Treg.

The physiological responses of Vallisneria natans to epiphytic algae with the increase of N and P concentrations in water bodies.

To reveal the mechanism of submerged plants decline in progressively eutrophicated freshwaters, physiological responses of Vallisneria natans to epiphytic algae were studied in simulation lab by measuring plant physiological indexes of chlorophyll content, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity based on a 2 × 4 factorial design with two epiphytic conditions (with epiphytic algae and without) and four levels of N and P concentrations in water (N-P[mg.L(-1)]: 0.5, 0.05; 2.5, 0.25; 4.5, 0.45; 12.5, 1.25). Compared with control (non-presence of epiphytic algae), chlorophyll contents of V. natans were significantly decreased (p < 0.01) for the presence of epiphytic algae under any concentrations of N and P in water bodies. While the presence of epiphytic algae induced peroxidation of membrane lipids, MDA contents of V. natans had significantly increased (p < 0.05) by comparing with control. SOD activity significantly enhanced (p < 0.05) with the presence of epiphytic algae in the treatments of T2 and T3 in the whole culture process by comparing with control, sometimes reaching an extremely significant level (p < 0.01). However, in the treatments of T1 and T4, SOD activity had no obvious change with the presence of epiphytic algae (p < 0.05) by comparing with control. At the end of the experiment, the effects of epiphytic algae on chlorophyll content and SOD activity in the leaves of V. natans were increased at first and then decreased with the concentrations of N and P in water, and MDA content became higher with the increase of N and P. concentrations. Repeated measurement data testing showed that the effects of epiphytic algae on the chlorophyll content and MDA content and SOD activity were significant, respectively (p < 0.001), the effects of epiphytic algae were combining with effects of concentrations of N and P (p < 0.001), respectively, and their interaction (p < 0.001). Our observations confirmed that this prediction: the growth of epiphytic algae directly produced adverse effects on physiology of V. natans and epiphytic algal biomass were positively correlated with nutrient available in the water column.

Association between leukocyte mitochondrial DNA content and risk of coronary heart disease: a case-control study.

OBJECTIVE: Compelling epidemiological evidence indicates that alterations of mitochondrial DNA (mtDNA), including mutations and abnormal content of mtDNA, are associated with the initiation and development of cardiovascular disease. This study was undertaken to investigate whether mtDNA content in peripheral blood leukocytes (PBLs) could be used as a risk predictor for coronary heart disease (CHD). METHODS: The mtDNA content of PBLs from 378 CHD patients and 378 matched healthy controls was measured using quantitative real-time PCR-based method in a case-control study. An unconditional multivariate logistic regression model was applied to estimate the association between leukocyte mtDNA content and CHD risk. RESULTS: CHD patients exhibited notably lower mtDNA content than matched healthy controls (median, 0.65 vs. 0.86; P < 0.001). Compared with individuals who had high mtDNA content, individuals who had low mtDNA content had a significantly increased risk of CHD (adjusted OR, 2.38; 95% confidence interval, 1.33-4.69). A significant dose-response relation was observed between increased CHD risk and lower mtDNA content (Ptrend < 0.001). Furthermore, there was a significantly positive mtDNA content correlation between PBLs and atherosclerotic plaque tissue (ρ = 0.627, P = 0.039). In addition, a significant joint effect on the risk of CHD was noted between mtDNA content and cigarette smoking or plasma LDL-C concentration. CONCLUSIONS: This present study provide the first epidemiologic evidence linking low mtDNA content in PBLs to an increased CHD risk, which warrants further investigation in other populations.

Screening active components from Yu-ping-feng-san for regulating initiative key factors in allergic sensitization.

Yu-ping-feng-san (YPFS) is a Chinese medical formula that is used clinically for allergic diseases and characterized by reducing allergy relapse. Our previous studies demonstrated that YPFS efficiently inhibited T helper 2 cytokines in allergic inflammation. The underlying mechanisms of action of YPFS and its effective components remain unclear. In this study, it was shown that YPFS significantly inhibited production of thymic stromal lymphopoietin (TSLP), an epithelial cell-derived initiative factor in allergic inflammation, in vitro and in vivo. A method of human bronchial epithelial cell (16HBE) binding combined with HPLC-MS (named 16HBE-HPLC-MS) was established to explore potential active components of YPFS. The following five components bound to 16HBE cells: calycosin-7-glucoside, ononin, claycosin, sec-o-glucosylhamaudol and formononetin. Serum from YPFS-treated mice was analyzed and three major components were detected claycosin, formononetin and cimifugin. Among these, claycosin and formononetin were detected by 16HBE-HPLC-MS and in the serum of YPFS-treated mice. Claycosin and formononetin decreased the level of TSLP markedly at the initial stage of allergic inflammation in vivo. Nuclear factor (NF)-κB, a key transcription factor in TSLP production, was also inhibited by claycosin and formononetin, either in terms of transcriptional activation or its nuclear translocation in vitro. Allergic inflammation was reduced by claycosin and formononetin when they are administered only at the initial stage in a murine model of atopic contact dermatitis. Thus, epithelial cell binding combined with HPLC-MS is a valid method for screening active components from complex mixtures of Chinese medicine. It was demonstrated that the compounds screened from YPFS significantly attenuated allergic inflammation probably by reducing TSLP production via regulating NF-κB activation.

[Effect of pig manure and rice straw on biological activity of Cd-contaminated soil].

Studies on the effects of pig manure and rice straw on the biological activity of Cd-contaminated permeable paddy soil showed that Cd-contaminated soil had a declined biological activity. After applying organic manure, the content of soil available Cd decreased significantly, being about 40%, and soil microbial C, N and P and soil dehydrogenase and catalase activities increased 30%-100%. There existed a negative correlation between soil available Cd and soil microbial C and N, indicating that microbial C and N could be used as an index of Cd-contaminated soil.