P-N heterostructures based on transition-metal dichelcongenides (TMDs) and a conventional semiconductor, such as p-Si, have been considered a promising structure for next-generation electronic devices and applications. However, synthesis of high-quality, wafer-scale TMDs, particularly WS2 on p-Si, is challenging. Herein, we propose an efficient method to directly grow WS2 crystals on p-Si via a hybrid thermolysis process. The WO3 is deposited to prepare the p-Si surface for coating of the (NH4)2WS4 precursor and converted to WS2/p-Si during thermolysis. Moreover, the WS2/p-Si heterojunction photocathode is fabricated and used in solar hydrogen production. The fabricated n-WS2/p-Si heterojunction provided an onset potential of +0.022 V at 10 mA/cm2 and a benchmark current density of -9.8 ± 1.2 mA/cm2 at 0 V. This method reliably and efficiently produced high-quality, wafer-scale WS2 crystals and overcame the challenges associated with previous approaches. The approach developed in this research demonstrates a magnificent progress in the fabrication of 2D material-based electronic devices.
Abstract The development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar‐driven water splitting. Here, we first introduce indium oxide (In 2 O 3 ) nanorods (NRs) as a novel electron transport layer for bismuth vanadate (BiVO 4 ) with a short charge diffusion length. In 2 O 3 NRs reinforce the electron transport and hole blocking of BiVO 4 , surpassing the state‐of‐the‐art photoelectrochemical performances of BiVO 4 ‐based photoanodes. Also, a tannin–nickel–iron complex (TANF) is used as an oxygen evolution catalyst to speed up the reaction kinetics. The final TANF/BiVO 4 /In 2 O 3 NR photoanode generates photocurrent densities of 7.1 mA cm −2 in sulfite oxidation and 4.2 mA cm −2 in water oxidation at 1.23 V versus the reversible hydrogen electrode. Furthermore, the “artificial leaf,” which is a tandem cell with a perovskite/silicon solar cell, shows a solar‐to‐hydrogen conversion efficiency of 6.2% for unbiased solar water splitting. We reveal significant advances in the photoactivity of TANF/BiVO 4 /In 2 O 3 NRs from the tailored nanostructure and band structure for charge dynamics.
This study presents a new ultra-high temperature composite fabricated by using zirconium diboride (ZrB2), silicon carbide (SiC), and tantalum carbide (TaC) with the volume ratios of 70%, 20%, and 10%, respectively. To attain this novel composite, an advanced processing technique of spark plasma sintering (SPS) was applied to produce ZrB2-SiC-TaC. The SPS manufacturing process was achieved under pressure of 30 MPa, at 2000 °C for 5 min. The micro/nanostructure and mechanical characteristics of the composite were clarified using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and nano-indentation. For further investigations of the product and its characteristics, X-ray fluorescence (XRF) analysis and X-ray photoelectron spectroscopy (XPS) were undertaken, and the main constituting components were provided. The composite was densified to obtain a fully-dense ternary; the oxide pollutions were wiped out. The mean values of 23,356; 403.5 GPa; and 3100 °C were obtained for the rigidity, elastic modulus, and thermal resistance of the ZrB2-SiC-TaC interface, respectively. To explore the practical application of the composite, the natural frequency of an aircraft wing considering three cases of materials: i) with a leading edge made of ZrB2-SiC-TaC; ii) the whole wing made of ZrB2-SiC-TaC; and iii) the whole wing made of aluminum 2024-T3 were investigated employing a numerical finite element model (FEM) tool ABAQUS and compared with that of a wing of traditional materials. The precision of the method was verified by performing static analysis to obtain the responses of the wing including total deformation, equivalent stress, and strain. A comparison study of the results of this study and published literature clarified the validity of the FEM analysis of the current research. The composite produced in this study significantly can improve the vibrational responses and structural behavior of the aircraft's wings.
Meigs' syndome consists of an ovarian fibroma, or fibroma-like benign tumor, associated with fluid in both abdomen and chest. Characteristically, the ascites and hydrothorax disappeared and do not recurred following removal of the ovarian tumor. The authors presented a case of Meigs' syndrome that was cured by surgical removal of ovarian tumor and resulted in normal pregnancy outcome in 27-year-old pregnant woman with a brief review of literatures.
Objective : To determine whether the presence of fetal fibronectin in the cervicovaginal secretion could be used as a clinical marker to predict the outcome of labor induction. Methods : The study group comprised 58 term pregnant women with intact amnionic membranes, 44 without labor and 14 with irregular labor. All patients had been admitted for induction of labor during Sept. 1, 1999 to Dec. 31, 1999 at the Department of Obstetrics and Gynecology of Yeungnam University Hospital. Fetal fibronectin was assayed with the cervicovaginal secretion. We analyzed the variables of labor outcome by the presence (positove) or absence (negative) of fetal fibronectin and the modified Bishop score. Results : Cervicovaginal fetal fibronectin was detected in 75.0% (33/44) of the women without labor and 85.7% (12/ 14) with irregular labor, and 76.3% (29/38) with Bishop score 4 or less and 80.0% (16/20) with score 5 or above. There was no statistical differences in the positive rate of fetal fibronectin between the women without labor and those with irregular labor, and the women with Bishop score 4 or less and those with Bishop score 5 or above, respectively. The mean oral tablets used for cervical ripening, the mean time interval from the beginning of labor induction to delivery, and the mean cesarean delivery rate were 1.972.56 tabs and 3.122.42, 10.12 6.56 hours and 13.886.14, and 20.0% and 38.4%, in the women with positive fetal fibronectin and those with negative respectively, and 1.832.50 and 2.422.60, 10.117.17 hours and 11.286.26 hours, and 10.0% and 31.6% in the women with Bishop score 5 or above and those with Bishop score 4 or less, respectively. There were no statistical differences in the mean values between the women with positive and negative fetal fibronectin, and between Bishop score 5 or above and Bishop score 4 or less, respectively. There were no statistical differences in the mean oral tablets used for cervical ripening (2.00 265 vs. 4.401.82) and the mean time interval from the beginning of labor induction to delivery (10.11 7.53 vs. 16.175.38), between the women with positive fetal fibronectin and Bishop score 5 or above and those with negative fetal fibronectin and Bishop score 4 or less, respectively. However, the cesarean delivery rate was significantly lower in the women with positive fetal fibronectin and Bishop score 5 or above than those with negative fetal fibronectin and Bishop score 4 or less (6.3% vs 44.4%, p=0.040). Conclusion : The assesment of cervicovaginal fetal fibronectin and Bishop score could be useful in predicting the success or failure of labor induction. But it was not helpful to predict the easiness of labor induction by the presence or absence of fetal fibronectin in the cervicovaginal secretion and/or modified Bishop score.
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