The fluctuated structural/electronic properties of SrTiO3two-dimensional materials caused by surface effects.

Perovskite oxide thin films have many astonishing properties, such as multiferroicity, superconductivity, strong correlation, etc, and are closely related to orientations with different symmetry and structural characteristics. Recently, perovskite oxide films with only one unit cell thickness have been synthesized successfully (Jiet al2019Nature57087-90). Here we investigated the structure and electronic properties of SrTiO3(STO) two-dimensional (2D) materials with (001), (110), and (111) surfaces. We found that due to surface effects caused atomic distortion fluctuations, the lattice constant and thickness of STO 2D materials with the (110) surface fluctuate sharply with the increase of atomic layers. The band gap of STO 2D materials exhibits oscillation as the number of atomic layers increases, due to the different atomic distortion and surface reconstruction with odd and even atomic layers. The STO 2D materials along (001) surfaces with different atomic layers are always semiconductors. As the atomic layers increasing, the electronic structure of STO 2D materials with (110) or (111) surfaces continuously transitioning between semiconductor and metallic phases, and finally totally become metallic phases, which is closely related to the surface reconstruction effect. The differences between STO 2D materials along the (001) and (110) or (111) surfaces are significant and can be explained by mixed Sr-d, Ti-d, and O-p orbitals. Our studies may provide new insights into the surface effects of perovskite oxide 2D materials.

Parameter Optimization of RB-SiC Polishing by Femtosecond Laser.

Reaction-boned silicon carbide (RB-SiC) is considered a new material for large lightweight ground-based space telescopes due to its high specific stiffness, low thermal deformation, and excellent optical quality. The excellent mechanical properties of RB-SiC result in the low efficiency of traditional polishing and mechanical polishing. In this paper, a polishing method for RB-SiC based on a femtosecond laser is proposed to improve surface quality. A theoretical heat conduction model was established in the process of femtosecond laser irradiation of SiC. We analyzed the ablation type and calculated the single-pulse ablation threshold of SiC, which verified the feasibility of femtosecond laser polishing. Further, the effects of polishing parameters on the polished surface quality were analyzed by a series of experiments, and the optimal parameters were selected. It was observed to improve polishing efficiency and can replace the intermediate steps of traditional mechanical polishing.

Creating Augmented Reality Holograms for Polytrauma Patients Using 3D Slicer and Holomedicine Medical Image Platform.

In traumatology physicians heavily rely on computed tomography (CT) 2D axial scans to identify and assess the patient's injuries after an accident. However, in some cases it can be difficult to rigorously evaluate the real extent of the damage considering only the bidimensional slices produced by the CT, and some life-threatening lesions can be missed. With the development of 3D holographic rendering and extended reality (XR) technology, CT images can be projected in a 3D format through head-mounted holographic displays, allowing multi-view from different angles and interactive slice intersections, thus increasing anatomical intelligibility. In this article, we explain how to import CT scans into holographic displays for 3D visualization and further compare the methodolgy with traditional bidimensional reading.

[Risk Factors for Surgical Site Infection after Conversion from Laparoscopic to Open Cholecystectomy].

Objective To investigate the incidence of surgical site infection(SSI)following conversion from laparoscopic to open cholecystectomy and to analyze the related risk factors. Methods The clinical data of 179 patients who had experienced conversion from laparoscopic to open cholecystectomy in Peking Union Medical College Hospital from January 2014 to August 2019 were analyzed retrospectively.Univariate and multivariate logistic regression analyses were performed to evaluate the associations between clinical variables and SSI. Results The incidence of SSI was 19.0%(34/179)after conversion from laparoscopic to open cholecystectomy.The multivariable analysis demonstrated that preoperative endoscopic retrograde cholangiopancreatography(ERCP)(OR=4.208,95% CI:1.590-11.135,P=0.004)was the only independent risk factor of SSI. Conclusions The incidence of SSI after conversion from laparoscopic to open cholecystectomy increased remarkably,especially in those who had preoperative ERCP.Preventive interventions should be taken to reduce the incidence of SSI.

Urinary Exosomal CA9 mRNA as a Novel Liquid Biopsy for Molecular Diagnosis of Bladder Cancer.

OBJECTIVE: The objective of this study was to assess the possibility of using urinary exosomal CA9 mRNA as a novel liquid biopsy for the molecular diagnosis of bladder cancer. PATIENTS AND METHODS: A total of 168 bladder cancer patients and 90 control subjects were included in the study. An isolation kit was used to isolate urinary exosomes. Transmission electron microscopy (TEM) was used to examine the presence of exosomes. Flow cytometry was used to examine the exosomal marker CD63. The expression level of exosomal CA9 mRNA was detected by RT-qPCR. The diagnostic performance of urinary urinary exosomal CA9 mRNA was evaluated. RESULTS: TEM confirmed the enriched exosomes from urinary bladder patients. Flow cytometry indicated a strong positive expression of exosome marker CD63. Successful extraction of RNA was performed from exosome samples. The level of urinary exosomal CA9 mRNA was significantly higher in bladder cancer group than in control group (p<0.001). The area under the ROC curve was 0.837 (95% CI: 0.743-0.859) with a sensitivity of 85.18% and a specificity of 83.15% for the diagnosis of bladder cancer. CONCLUSION: We found that the urinary exosomes were abundant in the urine of bladder cancer patients. CA9 mRNA could be detectable in urinary exosomes. The urinary exosomal CA9 mRNA may present a new liquid biopsy for the diagnosis of bladder cancer.