Novel structures of two-dimensional tungsten boride and their superconductivity.

Two-dimensional (2D) superconductors, which can be widely applied in optoelectronic and microelectronic devices, have gained renewed attention in recent years. Based on the crystal structure prediction method and first-principles calculations, we obtain four novel 2D tungsten boride structures of tetr-, hex-, and tri-W2B2 and hex-WB4 and investigate their bonding types, electronic properties, phonon dispersions and electron-phonon coupling (EPC). The results show that both tetr- and hex-W2B2 are intrinsic phonon-mediated superconductors with a superconducting transition temperature (Tc) of 7.8 and 1.5 K, respectively, while tri-W2B2 and hex-WB4 are normal metals. We demonstrate that carrier doping as well as biaxial strain can soften the low-frequency phonon modes and enhance the strength of the EPC. While the Tc of tetr-W2B2 can be increased to 15.4 K under a compressive strain of -2%, the Tc of hex-W2B2 can be enhanced to 5.9 K by a tensile strain of +4%. With the inclusion of spin-orbit couping (SOC), the value of Tc decreases by 38.5% in our systems. Furthermore, we explore the stabilities and mechanical properties of tetr- and hex-W2B2 and indicate that they may be prepared by growing on ZnS(100) and ZnS(111), respectively. Our findings provide novel 2D superconducting materials and will stimulate more efforts in this filed.

A univariate ternary logic and three-valued multiplier implemented in a nano-columnar crystalline zinc oxide memristor.

Memristors, which feature small sizes, fast speeds, low power, CMOS compatibility and nonvolatile modulation of device resistance, are promising candidates for next-generation data storage and in-memory computing paradigms. Compared to the binary logics enabled by memristor devices, ternary logics with larger information-carrying capacity can provide higher computation efficiency with simple operation schemes, reduced circuit complexity and smaller chip areas. In this study, we report the fabrication of memristor devices based on nano-columnar crystalline ZnO thin films; they show symmetric and reliable multi-level resistive switching characteristics over three hundred cycles, which benefits the implementation of univariate ternary logic operations. Experimental results demonstrate that a three-valued logic complete set can be realized by the univariate operations of the present ZnO memristor device, and a ternary multiplier unit circuit is designed for potential applications. The present methodology can be beneficial for constructing future high-performance computation architectures.

[Effect of hypobaric hypoxic preconditioning on surgically induced endometriosis by allotransplant of uterine tissue in rats].

OBJECTIVE: To determine the effects of hypobaric hypoxia pretreatment on surgically induced endometriosis in rats. METHODS: Six rats were randomized into 2 groups and exposed to hypoxia (8% O2) and normoxia (21% O2) for 8 h. The uterine endometrium was intraperitoneally implanted into estrogen-treated ovariectomized Lewis rat, and the growth and quality of the implants were measured. The changes in apoptosis, protein and gene expressions in the serum, abdominis effusion fluids and implants were tested by ELISA, immunohistochemical staining, TUNNEL assay, Western blotting and RT-PCR. RESULTS: The volume of the implants in the hypoxic pretreatment group was significantly increased compared with the normoxia group. High expressions of Ki67, CD31, VEGF, and HIF-1α and lowered cell apoptosis were found in the hypoxia-pretreated implants compared with the normoxic group. VEGF level in the serum and peritoneal fluid were increased in hypoxia-pretreated group, but TNFα level was comparable between the 2 groups. CONCLUSION: Hypoxia play an important role in the occurrence and progression of endometriosis by increasing cell proliferation and angiogenesis and decreasing cell apoptosis in the implants in the rat model.

[Expression of pituitary tumor transforming gene in human renal clear cell carcinoma and its significance].

OBJECTIVE: To explore the expression of pituitary tumor transforming gene (PTTG) in human renal clear cell carcinoma (RCCC) and its significance. METHODS: PTTG protein expression was detected by immunohistochemistry in 87 RCCC and 45 paired normal renal tissues. RESULTS: PTTG was expressed differentially between the normal renal and RCCC tissues. Compared with normal tissues, the primary RCCC tissues showed significantly increased expression of PTTG protein (P<0.001). The positive rate of PTTG protein was positively correlated to the tumor size, clinical stage and Fuhrman grade of RCCC (P=0.009, 0.008 and 0.035, respectively). CONCLUSION: Increased PTTG protein expression may be involved in the carcinogenesis and progression of RCCC.

Efficient Suzuki-Type Cross-Coupling of Enantiomerically Pure Cyclopropylboronic Acids.

Optically active cyclopropanes (e.g. 1) can be prepared by the use of tartaric acid derivatives as chiral auxiliaries in the palladium-catalyzed cross-coupling of optically active cyclopropylboronic acids with electrophiles. The absolute configuration of the chiral carbon atom is retained, and the reaction proceeds with good yields and enantiomeric excesses. R=H, p-Ph, o-CO2 CH3 , p-CO2 CH3 , p-NO2 , o-OCH3 , m-OCH3 .