Analysis of blood coagulation indexes, thromboelastogram and autoantibodies in patients with recurrent pregnancy loss.

Objectives: Changes in coagulation indexes, thromboelastogram(TEG) and autoantibodies in patients with recurrent pregnancy loss (RPL) with different number of abortions were analyzed. Methods: Medical records of 48 patients with recurrent abortion, treated in Quzhou people's Hospital from November 2019 to October 2020, were collected as the observation group. Based on the number of abortions, patients were divided into Group-A (Two abortions, n=21), Group-B (Three abortions, n=16) and group C (Abortion ≥ four times, n=11). Records of 50 healthy pregnant women in our hospital in the same period were selected as the control group. Coagulation indexes [prothrombin time (PT), activated partial prothrombin time (APTT), fibrinogen (FIB), D-Dimer (DD)], thromboelastogram (TEG) parameters [reaction time (R), coagulation time(K), maximum thrombus amplitude (MA), coagulation angle (α)], changes in the levels of autoantibodies [anticardiolipin antibody (ACA), anti-endometrial antibody (EmAb), anti-thyroid antibody(ATA)] were compared between the groups. Results: There were significant differences in the levels of ATPP, Pt, FIB and DD among the groups. Higher number of abortions correlated with lower the levels of ATPP and Pt, and higher levels of FIB and DD (P<0.05). Compared to the control group, R and K in Group-A,B and C decreased, while α and MA increased (P<0.05). There were significant differences in α and MA indexes. The positive rates of ACA, EmAb and ATA in Group-A were higher than those in the control group, but the difference was not statistically significant (P>0.05), while the above indexes in groups B and C were significantly higher than those in the control group (P<0.05). The positive rates of ACA and ATA in group C were significantly higher than those in Group-A (P<0.05), but there was no significant difference in the positive rate of EmAb (P>0.05). Conclusion: RPL was related to the decrease of APTT, PT, and the increase of FIB and DD levels. TEG indicated that the increase of α and MA values indicated that the risk of multiple abortion was increased. The positive rates of ACA, EmAb and ATA were closely related to multiple abortions, especially the positive rates of ACA and ATA.

Design and Optimize the Performance of Self-Powered Photodetector Based on PbS/TiS3 Heterostructure by SCAPS-1D.

Titanium trisulphide (TiS3) has been widely used in the field of optoelectronics owing to its superb optical and electronic characteristics. In this work, a self-powered photodetector using bulk PbS/TiS3 p-n heterojunction is numerically investigated and analyzed by a Solar Cell Capacitance Simulator in one-Dimension (SCAPS-1D) software. The energy bands, electron-holes generation or recombination rate, current density-voltage (J-V), and spectral response properties have been investigated by SCAPS-1D. To improve the performance of photodetectors, the influence of thickness, shallow acceptor or donor density, and defect density are investigated. By optimization, the optimal thickness of the TiS3 layer and PbS layer are determined to be 2.5 µm and 700 nm, respectively. The density of the superior shallow acceptor (donor) is 1015 (1022) cm-3. High quality TiS3 film is required with the defect density of about 1014 cm-3. For the PbS layer, the maximum defect density is 1017 cm-3. As a result, the photodetector based on the heterojunction with optimal parameters exhibits a good photoresponse from 300 nm to 1300 nm. Under the air mass 1.5 global tilt (AM 1.5G) illuminations, the optimal short-circuit current reaches 35.57 mA/cm2 and the open circuit voltage is about 870 mV. The responsivity (R) and a detectivity (D*) of the simulated photodetector are 0.36 A W-1 and 3.9 × 1013 Jones, respectively. The simulation result provides a promising research direction to further broaden the TiS3-based optoelectronic device.

Facile synthesis of a dual-phase CsPbBr3-CsPb2Br5 single crystal and its photoelectric performance.

The emerging metal-halide perovskites are promising for next generation optoelectronic devices. Recently, all-inorganic halide perovskites have been developed and show significantly improved stability compared with organic-inorganic hybrid halide perovskites. Here, we report a facile method based on the coffee ring effect of solvents to synthesize dual-phase CsPbBr3-CsPb2Br5 single crystal microsheets for the first time. The prepared dual-phase CsPbBr3-CsPb2Br5 single crystal is composed of a tetragonal crystalline phase of CsPb2Br5 and a monoclinic phase of CsPbBr3 according to X-ray diffraction (XRD) patterns. The sharp XRD peaks indicate the high crystallinity of the as-synthesized dual-phase CsPbBr3-CsPb2Br5 microsheets. CsPbBr3 is mainly distributed on the edge of the microsheets based on photoluminescence (PL) mapping images. Besides, a photodetector based on the dual-phase CsPbBr3-CsPb2Br5 microsheets exhibits good performance with a high on/off photocurrent ratio of 300 and a photoresponsivity of 2.68 mA W-1. The rise and decay times of the CsPbBr3-CsPb2Br5 microsheet photodetector are around 25.3 ms and 29.6 ms, respectively. The experimental results indicate that the dual-phase CsPbBr3-CsPb2Br5 microsheet could be a good candidate for the fabrication of high-performance micro photodetectors compatible with practical applications.

Post-Treatment of CH3 NH3 PbI3 /PbI2 Composite Films with Methylamine to Realize High-Performance Photoconductor Devices.

Organometallic halide perovskites have attracted great research interest as light-active materials for use in optoelectronics. Here, we report a high-performance photoconductor based on a methylammonium lead iodide (MAPbI3 ) film that was prepared from a methylamine-treated MAPbI3 /PbI2 perovskite film. An ultrahigh responsivity of 3.6 A W-1 and detectivity of 5.4×1012  Jones were obtained for the film under 0.5 mW cm-2 white-light illumination. In addition, under 420 nm light irradiation, the film exhibited its highest responsivity and detectivity of 30 A W-1 and 2.4×1014  Jones, respectively. The excellent photo-response performance results from the improved electronic quality and suppressed nonradiative recombination channels of the treated perovskite thin film.

Two-Dimensional Hybrid Composites of SnS2 Nanosheets Array Film with Graphene for Enhanced Photoelectric Performance.

Two-dimensional (2D) metal dichalcogenides have attracted considerable attention for use in photoelectric devices due to their unique layer structure and strong light-matter interaction. In this paper, vertically grown SnS2 nanosheets array film was synthesized by a facile chemical bath deposition (CBD). The effects of deposition time and annealing temperature on the quality of SnS2 films was investigated in detail. By optimizing the preparation conditions, the SnS2 array film exhibited efficient photoelectric detection performance under sunlight. Furthermore, in order to improve the performance of the photodetector based on SnS2 nanosheets film, a transparent graphene film was introduced as the hole-transport layer by wet-chemical method directly transferring techniques. Graphene/SnS2 nanosheets array film heterojunction photodetectors exhibit enhanced photoresponsivity. The light on/off ratio of the photodetector based on graphene/SnS2 was 1.53, about 1.4 times higher than that of the pristine SnS2 array films. The improved photoresponse performance suggested that the effective heterojunction between vertical SnS2 nanosheets array film and graphene suppresses the recombination of photogenerated carriers. The results indicate that the graphene/SnS2 heterojunction photodetectors have great potential in photodetection devices.

High-Performance Photoresistors Based on Perovskite Thin Film with a High PbI2 Doping Level.

We prepared high-performance photoresistors based on CH3NH3PbI3 films with a high PbI2 doping level. The role of PbI2 in CH3NH3PbI3 perovskite thin film was systematically investigated using scanning electron microscopy, X-ray diffraction, time-resolved photoluminescence spectroscopy, and photoconductive atomic force microscope. Laterally-structured photodetectors have been fabricated based on CH3NH3PbI3 perovskite thin films deposited using precursor solution with various CH3NH3I:PbI2 ratios. Remarkably, the introduction of a suitable amount of PbI2 can significantly improve the performance and stability of perovskite-based photoresistors, optoelectronic devices with ultrahigh photo-sensitivity, high current on/off ratio, fast photo response speed, and retarded decay. Specifically, a highest responsivity of 7.8 A/W and a specific detectivity of 2.1 × 1013 Jones with a rise time of 0.86 ms and a decay time of 1.5 ms have been achieved. In addition, the local dependence of photocurrent generation in perovskite thin films was revealed by photoconductive atomic force microscopy, which provides direct evidence that the presence of PbI2 can effectively passivate the grain boundaries of CH3NH3PbI3 and assist the photocurrent transport more effectively.

Location-selective growth of two-dimensional metallic/semiconducting transition metal dichalcogenide heterostructures.

An electrical contact between metallic electrodes and semiconductors is critical for the performance of electronic and optoelectronic devices. Two-dimensional (2D) transition metal dichalcogenides (TMDs) contain semiconducting, metallic and insulating material members, which enables the fabrication of highly integrated electronic devices fully based on 2D TMDs. However, location-selective synthesis of metallic/semiconducting heterostructures by a chemical vapor deposition (CVD) method has rarely been reported. In this study, a two-step CVD method was applied to fabricate 2D metallic/semiconducting heterostructures. Semiconducting WS2 was first synthesized and served as the template for the following CVD growth of metallic NbS2. In the growth process, NbS2 flakes selectively nucleate at the edges of WS2 monolayers, thus resulting in the formation of NbS2 islands circling around the WS2 monolayers. The as-grown NbS2/WS2 heterostructure was further systematically characterized by Raman spectroscopy, atomic force microscopy (AFM) and scanning transition electron microscopy (STEM). The NbS2 layers epitaxially grown on the WS2 monolayers exhibit a 3R phase and there was no discernible lattice strain in the NbS2/WS2 van der Waals (vdW) heterostructure. The growth of the metallic/semiconducting 2D heterostructures could benefit the nanoelectronic device fabrication and provide a platform for the 2D contact resistance study.

Thermal-Assisted Vertical Electron Injections in Few-Layer Pyramidal-Structured MoS2 Crystals.

The interlayer screening effects and charge conduction mechanisms in atomically thin two-dimensional (2D) materials are crucial for electronics and optoelectronics applications. However, such effects remain largely unexplored in chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS2) crystals. Here, we report a controllable CVD-grown monolayer MoS2 and layer-by-layer pyramidal-structured MoS2 crystals with an oxidized Mo foil precursor. The interlayer screening effects and charge conduction mechanisms in the pyramidal-structured MoS2 crystals are studied. Although the Fowler-Nordheim (FN) tunneling model is widely adopted to describe the vertical charge transport mechanism at the 2D semiconductor/bulk metal interface, we found that such a mechanism cannot satisfactorily explain the electrical measurement obtained from our CVD-grown MoS2 samples. Instead, our analysis reveals that Richardson-Schottky (RS) emission is the dominant transport mechanism when Vbias < 1 V. Our findings provide a fundamental understanding of the charge conduction mechanism in CVD-grown MoS2 crystals, which is crucial for development of MoS2 electronics and optoelectronics devices.

Boosting the Electrocatalytic Water Oxidation Performance of CoFe2O4 Nanoparticles by Surface Defect Engineering.

Spinel oxides have attracted widespread interest for electrocatalytic applications owing to their unique crystal structure and properties. The surface structure of spinel oxides significantly influences the electrocatalytic performance of spinel oxides. Herein, we report a Li reduction strategy that can quickly tune the surface structure of CoFe2O4 (CFO) nanoparticles and optimize its electrocatalytic oxygen evolution reaction (OER) performance. Results show that a large number of defective domains have been successfully introduced at the surface of CFO nanopowders after Li reduction treatment. The defective CFO nanoparticles demonstrate significantly improved electrocatalytic OER activity. The OER potential observed a negative shift from 1.605 to 1.513 V at 10 mA cm-2, whereas the Tafel slope is greatly decreased to 42.1 mV dec-1 after 4 wt % Li reduction treatment. This efficient Li reduction strategy can also be applied to engineer the surface defect structure of other material systems and broaden their applications.

Direct Observation of Perovskite Photodetector Performance Enhancement by Atomically Thin Interface Engineering.

Lead trihalide perovskites have been integrated with atomically thin WS2 and served as absorption layers to improve photoresponsivity in photodetectors. The combination of perovskites and two-dimensional (2D) transition-metal dichalcogenide (TMDC) materials provides the platform to study light-matter interactions and charge transfer mechanisms in optoelectronic devices. Herein, conductive and photoconductive atomic force microscopy were used to image the dark current and photocurrent generated in WS2/CH3NH3PbI3 (MAPbI3) heterostructures. Dark current measurement in the applied voltage range displays characteristic diode behavior, which can be well described by thermionic emission theory. Under laser illumination at 532 nm, the spatially resolved photocurrent images exhibit location-dependent photoresponse, where the photocurrent increases remarkably for the WS2/MAPbI3 heterostructures compared with the bare MAPbI3 regions. Furthermore, comparative surface roughness and 2D Fourier analysis of the topographic and current maps reveal that the interfacial conditions of the WS2/MAPbI3 heterojunctions play an important role in the charge separation process. In addition, WS2/MAPbI3-based photodetectors have been fabricated. Our study provides direct evidence that atomically thin TMDC monolayers can effectively assist the charge separation process and improve the light-to-electric energy conversion, which aids in the design principles and understanding of 2D heterostructured optoelectronic devices.

Significant photoluminescence enhancement in WS2 monolayers through Na2S treatment.

Tungsten disulfide monolayers have attracted extensive attention in nanoelectronics and optoelectronics applications due to their remarkable electronic and optical properties. High-quality WS2 monolayers with a scalable size and uniform thickness can be synthesized by a chemical vapor deposition method (CVD). However, they commonly contain intrinsic structural defects and different populations of charge carriers, which are responsible for different contributions of excitons, trions, and biexcitons to their photoluminescence (PL) emission. Here, we adopt sodium sulphide (Na2S) solution to chemically treat CVD-grown WS2 monolayers by a simple immersing method. The results show that WS2 monolayers have a significantly enhanced PL emission by a factor of 25-fold and an obvious red-shift of the PL wavelength, resulting from the different excitonic states induced by effective n-type doping after Na2S treatment. This work provides a simple but promising chemical doping route to significantly improve the optical properties of WS2 monolayers and paves the way for the realization of practical WS2 monolayer based optoelectronic applications.

Enhanced photovoltaic properties of perovskite solar cells by TiO2 homogeneous hybrid structure.

In this paper, we fabricated a TiO2 homogeneous hybrid structure for application in perovskite solar cells (PSCs) under ambient conditions. Under the standard air mass 1.5 global (AM 1.5G) illumination, PSCs based on homogeneous hybrid structure present a maximum power conversion efficiency of 5.39% which is higher than that of pure TiO2 nanosheets. The enhanced properties can be explained by the better contact of TiO2 nanosheets/nanoparticles with CH3NH3PbI3 and fewer pinholes in electron transport materials. The advent of such unique structure opens up new avenues for the future development of high-efficiency photovoltaic cells.

[Study of celluar toxicity and antibacterial property of nano-silver coating modified denture base].

OBJECTIVE: To investigate celluar toxicity and antibacterial property of nano-silver coating modified denture base and to provide a theortical basis for clinical application. METHOD: The samples were divided into coating group and denture base group. Samples in coating groups were treated with silver ion sputtering and were further divided into the 10, 20, 40, 60, 80, 100 s subgroups according to their sputtering time. Surface microstructure of samples in coating groups and denture base group were observed by scanning electron microscopy (SEM), and composition of material surface were determined with energy dispersive spectrum (EDS) analysis. Methyl thiazolyl terazolium (MTT) method was used to analysis L929 cells proliferation rate and cell toxicity grade while the coating groups (n = 6) and group test specimens (n = 6), negative control (polyethylene, PE) (n = 6) and positive control group (PVC-org.Sn) (n = 6) were co-cultured with L929 cells. The antibacterial properties of coating groups were investigated by using the bacterial membrane adhering method with Streptococcus mutans and Candida albicans. RESULTS: SEM observation showed that the surface of control group specimens were smooth, whereas dense and uniform distributed nano silver particles were visible on the surface of coating group specimens. The silver particles were round, and the diameter size was 10 nm. MTT assay showed that after being co-cultured with specimens in control group, L929 cell had higher proliferation rate than 100% at 24, 48, 72 h, and cytotoxicity were graded 0. The membrane adhering method results showed that all of bacterial colonies were found in control group, but without anything at the coating groups. CONCLUSIONS: Deposition of nano silver on the denture base surface by ion sputtering method is a viable method. There's no cytotoxicity of series Ag-coating material. Nano-silver modified denture base material benefits L929 cell surface proliferation and has antibacterial action.