Sugar-Derived Nanocrystalline Graphite Matrix C/C Composites with Excellent Ablative Resistance at 3000 °C.

Sugars are renewable resources essential to human life, but they are rarely used as raw materials for the industrial production of carbon-based materials, especially for the preparation of carbon fiber-reinforced carbon-matrix (C/C) composites, which are extremely useful for the semiconductor and aerospace sectors. Herein, a method utilizing sugar-derived carbon to replace petrochemicals as dense matrix to preparing C/C composites is reported. The matrix from sugar-derived C/C (S-C/C) composites has a nanocrystalline graphite structure that is highly thermally stable and effectively bonded to the carbon fibers. The mechanical properties of the S-C/C composite are comparable to those prepared from petrochemical sources; significantly, it exhibits a linear ablation rate of 0.03 mm s-1 after 200 s of ablation at 3000 °C in 10 MW m-2 heat flux. This new class of S-C/C is promising for use in a broad range of fields, ranging from semiconductor to aerospace.

The effect of intergenerational rearing on young children's self-control: The intervention effect of sports games.

Objective: To investigate the effect of different rearing arrangements on children's self-control and verify the promoting effect sports games might have on children's self-control in intergenerational rearing. Methods: A total of 72 intergenerational rearing children and 66 non-intergenerational rearing children were included in Experiment 1, in which the delay-of-gratification task was used to examine the differences in self-control among children with different rearing arrangements. In experiment 2, 70 intergenerational rearing children were included as subjects, and sports games were used to improve their self-control. Results: The results of experiment 1 showed that compared with non-intergenerational rearing children, the self-control ability of intergenerational rearing children was poor. In experiment 2, it was found that after the intervention with sports games, the self-control ability of the children in the intergenerational rearing group was effectively improved. Conclusion: Although intergenerational rearing arrangements have a certain negative impact on the self-control ability of children, the sports game intervention can be used to effectively develop the self-control ability of intergenerational rearing children.

The prognostic impact of BMI on colorectal cancer is stratified by tumor location.

Purpose: Recent studies have revealed the contrasting prognostic roles of body mass index (BMI) and tumor location in colorectal cancer (CRC). Given that right- and left-sided CRC may exhibit inverse effects on outcome and body weight, the present study aimed to examine whether the prognostic value of BMI and tumor location could be reciprocally stratified. Methods: This prospective, observational study recruited 4,086 patients diagnosed with stage III CRC from five independent clinical centers in China. The association of patients' outcomes with BMI and tumor location was evaluated hierarchically by Kaplan-Meier and Cox proportional-hazards models. Results: Although BMI was not associated with overall outcome, the association was significantly modified by tumor location. Among left-sided tumors, obesity and overweight were significantly associated with adverse overall survival (OS) and disease-specific survival (DSS). In contrast, among right-sided tumors, overweight was significantly associated with more favorable OS and DSS compared with the normal-weight group. The association of survival with tumor location did not reach statistical significance. However, hierarchical analysis by BMI revealed that left-sided tumors were associated with more favorable outcomes in the normal-weight group, while there was no statistically significant difference in the overweight or obese group. Conclusions: BMI and tumor location may have opposing effects on CRC prognosis, when stratified by each other, after adjusting for other known prognostic factors. These findings are the first to show the interactive prognostic impact of BMI and tumor location, which could be relevant to the stratification of patient management.

Sugar-Derived Isotropic Nanoscale Polycrystalline Graphite Capable of Considerable Plastic Deformation.

Obtaining large plastic deformation in polycrystalline van der Waals (vdW) materials is challenging. Achieving such deformation is especially difficult in graphite because it is highly anisotropic. The development of sugar-derived isotropic nanostructured polycrystalline graphite (SINPG) is discussed herein. The structure of this material preserves the high in-plane rigidity and out-of-plane flexibility of graphene layers and enables prominent plasticity by activating the rotation of nanoscale (5-10 nm) grains. Thus, micrometer-sized SINPG samples demonstrate enhanced compressive strengths of up to 3.0 GPa and plastic strains of 30-50%. These findings suggest a new pathway for enabling plastic deformation in otherwise brittle vdW materials. This new class of nanostructured carbon materials is suitable for use in a broad range of fields, from semiconductor to aerospace applications.

[Correlation between symptoms and their contribution to syndrome based on association rule combined with Bayesian network: syndrome of lung damp-heat accumulation in coronavirus disease 2019].

OBJECTIVE: To explore the correlation between symptoms and their contribution to syndrome based on syndrome of lung damp-heat accumulation in coronavirus disease 2019 (COVID-19), thus to provide methodological basis for the syndrome diagnosis. METHODS: Based on 654 clinical investigation questionnaires data of COVID-19 patients, a model based on syndrome of lung damp-heat accumulation was set. Using SPSS Modeler 14.1 software, association rules and Bayesian network were applied to explore the correlation between symptoms and their contribution to syndrome. RESULTS: There were 121 questionnaires referring to syndrome of lung damp-heat accumulation in total 654 questionnaires. The symptoms with frequency > 40% were fever (53.72%), cough (47.93%), red tongue (45.45%), rapid pulse (43.80%), greasy fur (42.15%), yellow tongue (41.32%), fatigue (40.50%) and anorexia (40.50%). Association rule analysis showed that the symptom groups with strong binomial correlation included fever, thirst, chest tightness, shortness of breath, cough, yellow phlegm, etc. The symptom groups with strong trinomial correlation included cough, yellow phlegm, phlegm sticky, anorexia, vomiting, heavy head and body, fever, thirst, fatigue, etc. Based on SPSS Modeler 14.1 software, with syndrome of lung damp-heat accumulation (yes = 1, no = 0) as target variable, and the selected symptoms with frequency > 15.0% as input variables, the Bayesian network model was established to obtain the probability distribution table of symptoms (groups), in which there was only one parent node (the upper node of each input variable) of fever, and the conditional probability was 0.54. The parent node of cough had yellow phlegm and syndrome of lung damp-heat accumulation, indicating that there was a direct causal relationship between cough and yellow phlegm in syndrome of lung damp-heat accumulation, and the conditional probability of cough was 0.99 under the condition of yellow phlegm. The common symptom groups and their contribution to syndrome were as follows: fever and thirsty (0.47), cough and yellow phlegm (0.49), chest tightness and polypnea (0.46), anorexia and heavy cumbersome head and body (0.61), yellow greasy fur and slippery rapid pulse (0.95). CONCLUSIONS: It is feasible and objective to analyze the correlation between symptoms and their contribution to syndromes by association rules combined with Bayesian network. It could provide methodological basis for the syndrome diagnosis.

Spin Rate Effects in a Micromachined Electrostatically Suspended Gyroscope.

Spin rate of a high-speed spinning-rotor gyroscope will make a significant impact on angular rate sensor performances such as the scale factor, resolution, measurement range, and bias stability. This paper presents the spin rate effects on performance indicators of a microelectromechanical systems (MEMS) gyroscope where a free-spinning rotor is electrostatically suspended in an evacuated vacuum cavity and functions as a dual-axis angular rate sensor. Theoretical models of the scale factor and measurement range of such a spinning-rotor gyroscope are derived. The experimental results indicate that the measured scale factors at different settings of the spin rate match well with the theoretical predication. In order to separate the disturbance component of the rotation control loop on the gyroscope output, a testing strategy is proposed by operating the gyroscope at different spin rates. Experimental results on a prototype gyroscope show that the squared drive voltage generated by the rotation control loop is approximately proportional to the noise of the gyroscope output. It was further investigated that an improved performance of such spinning-rotor gyroscopes can be achieved by operating the gyroscope rotor at an optimal spin rate.

Squeeze-Film Air Damping of a Five-Axis Electrostatic Bearing for Rotary Micromotors.

Air-film damping, which dominates over other losses, plays a significant role in the dynamic response of many micro-fabricated devices with a movable mass suspended by various bearing mechanisms. Modeling the damping characteristics accurately will be greatly helpful to the bearing design, control, and test in various micromotor devices. This paper presents the simulated and experimental squeeze-film air damping results of an electrostatic bearing for use in a rotary high-speed micromotor. It is shown that the boundary condition to solve the three-dimensional Reynolds equation, which governs the squeeze-film damping in the air gap between the rotor and its surrounding stator sealed in a three-layer evacuated cavity, behaves with strong cross-axis coupling characteristics. To accurately characterize the damping effect, a set of multiphysics finite-element simulations are performed by computing both the rotor velocity and the distribution of the viscous damping force acting on the rotor. The damping characteristics varying with several key structure parameters are simulated and discussed to optimize the device structure for desirable rotor dynamics. An electrical measurement method is also proposed and applied to validate the numerical results of the damping coefficients experimentally. Given that the frequency response of the electric bearing is critically dependent on the damping coefficients at atmospheric pressure, a solution to the air-film damping measurement problem is presented by taking approximate curve fitting of multi-axis experimental frequency responses. The measured squeeze-film damping coefficients for the five-axis electric bearing agrees well with the numerical solutions. This indicates that numerical multiphysics simulation is an effective method to accurately examine the air-film damping effect for complex device geometry and arbitrary boundary condition. The accurate damping coefficients obtained by FEM simulation will greatly simplify the design of the five-axis bearing control system and facilitate the initial suspension test of the rotor for various micromotor devices.

Carbon Nanofiber Arrays Grown on Three-Dimensional Carbon Fiber Architecture Substrate and Enhanced Interface Performance of Carbon Fiber and Zirconium Carbide Coating.

Carbon nanofibers (CNFs) were grown around the carbon fiber architecture through a plasma enhanced chemical vapor deposition method to enhance the interface performance between CF architecture substrate and ZrC preceramic matrix. The synthesized 3D CF hierarchical architectures (CNFs-CF) are coated with zirconium carbide (ZrC) ceramic to enhance their antioxidant property and high temperature resistance. The composition and the crystalline phase structure of the composite were detected with the X-ray photoelectron spectroscopy and X-ray diffraction. The results of scanning electron microscopy show that, the as-prepared CNFs and consistent ZrC ceramic coating are uniformly covered on the surface of carbon fiber architecture substrate. The ZrC ceramic products with excellent crystallinity were got from the pyrolysis of preceramic polymer at 1600 °C in inert atmosphere. Comparing with the untreated CF, the loading of ZrC ceramics around the CNFs-CF architecture surface are significantly increased. The thermal stability and mechanical property of CNFs-CF/ZrC nanocomposites have been promoted obviously compared with the CF/ZrC ceramic nanocomposite. The prepared CNFs-CF/ZrC ceramic nanocomposite is one of the potential candidate materials for the thermal protection application.

Vector-mediated Tum-5 expression in neovascular endothelial cells for treating hepatocellular carcinoma.

Hypervascular hepatocellular carcinoma (HCC) is one of the leading causes of cancer-associated mortality. Angiogenesis is an important contributor to HCC progression and metastasis; therefore, inhibiting angiogenesis may be an effective method of treating HCC. Tumstatin is a novel type of efficient endogenous vascular endothelial cell growth inhibiting factor. The anti-angiogenic activity of tumstatin is localized to the 54-132 amino acid region (Tum-5). In a previous study performed by our group, the gene fragment encoding Tum-5 was cloned and inserted into a pLXSN retroviral vector. In the present study, the anti-angiogenic effects of Tum-5 and the antitumor effects exerted by the pLXSN-Tum-5 vector in vivo were investigated. The results demonstrated that pLXSN-Tum-5 significantly inhibited the growth of human umbilical vein endothelial cells compared with pLXSN, but had no obvious effect on HepG2 cell growth. Moreover, the antitumor and anti-angiogenic activity of Tum-5 was examined in vivo using a xenograft of H22 HCC cells. The results indicated that pLXSN-Tum-5 significantly inhibited tumor growth following 5 injections over 10 days. The size and weight of tumors in the pLXSN-Tum-5 group were lower than those in the saline and pLXSN groups. Furthermore, immunohistochemical analysis with CD31 antibodies indicated that the average microvessel density in the pLXSN-Tum-5 group were significantly lower than that in the saline and pLXSN groups. These results suggested that Tum-5 exerts its antitumor activity by suppressing vascular endothelial cells. The gene fragment of Tum-5 may be developed as an effective inhibitor of angiogenesis and used to treat patients with HCC.

In Situ Growth of Core-Sheath Heterostructural SiC Nanowire Arrays on Carbon Fibers and Enhanced Electromagnetic Wave Absorption Performance.

Large-scale core-sheath heterostructural SiC nanowires were facilely grown on the surface of carbon fibers using a one-step chemical vapor infiltration process. The as-synthesized SiC nanowires consist of single crystalline SiC cores with a diameter of ∼30 nm and polycrystalline SiC sheaths with an average thickness of ∼60 nm. The formation mechanisms of core-sheath heterostructural SiC nanowires (SiCnws) were discussed in detail. The SiCnws-CF shows strong electromagnetic (EM) wave absorption performance with a maximum reflection loss value of -45.98 dB at 4.4 GHz. Moreover, being coated with conductive polymer polypyrrole (PPy) by a simple chemical polymerization method, the SiCnws-CF/PPy nanocomposites exhibited superior EM absorption abilities with maximum RL value of -50.19 dB at 14.2 GHz and the effective bandwidth of 6.2 GHz. The SiCnws-CF/PPy nanocomposites in this study are very promising as absorber materials with strong electromagnetic wave absorption performance.

Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension.

A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor being controlled by a torque-rebalance loop. In this paper, a decoupling compensation method is proposed and investigated experimentally based on an electrostatically suspended micromachined gyroscope. In order to eliminate the negative spring effect inherent in the gyroscope dynamics, a stiffness compensation scheme was utilized in design of the decoupled rebalance loop to ensure loop stability and increase suspension stiffness. The experimental results show an overall stiffness increase of 30.3% after compensation. A decoupling method comprised of inner- and outer-loop decoupling compensators is proposed to minimize the cross-axis coupling error. The inner-loop decoupling compensator aims to attenuate the angular position coupling. The experimental frequency response shows a position coupling attenuation by 14.36 dB at 1 Hz. Moreover, the cross-axis coupling between the two angular rate output signals can be attenuated theoretically from -56.2 dB down to -102 dB by further appending the outer-loop decoupling compensator. The proposed dual-loop decoupling compensation algorithm could be applied to other dual-axis spinning-rotor gyroscopes with various suspension solutions.

Self-Locking Avoidance and Stiffness Compensation of a Three-Axis Micromachined Electrostatically Suspended Accelerometer.

A micromachined electrostatically-suspended accelerometer (MESA) is a kind of three-axis inertial sensor based on fully-contactless electrostatic suspension of the proof mass (PM). It has the potential to offer broad bandwidth, high sensitivity, wide dynamic range and, thus, would be perfectly suited for land seismic acquisition. Previous experiments showed that it is hard to lift up the PM successfully during initial levitation as the mass needs to be levitated simultaneously in all six degrees of freedom (DoFs). By analyzing the coupling electrostatic forces and torques between three lateral axes, it is found there exists a self-locking zone due to the cross-axis coupling effect. To minimize the cross-axis coupling and solve the initial levitation problem, this paper proposes an effective control scheme by delaying the operation of one lateral actuator. The experimental result demonstrates that the PM can be levitated up with six-DoF suspension operation at any initial position. We also propose a feed-forward compensation approach to minimize the negative stiffness effect inherent in electrostatic suspension. The experiment results demonstrate that a more broadband linear amplitude-frequency response and higher suspension stiffness can be achieved, which is crucial to maintain high vector fidelity for potential use as a three-component MEMS geophone. The preliminary performance tests of the three-axis linear accelerometer were conducted under normal atmospheric pressure and room temperature. The main results and noise analysis are presented. It is shown that vacuum packaging of the MEMS sensor is essential to extend the bandwidth and lower the noise floor, especially for low-noise seismic data acquisition.

MicroRNA-650 expression in glioma is associated with prognosis of patients.

MicroRNAs are known as non-coding RNAs that regulate the expression of target mRNA. Accumulating evidence has indicated that microRNA expression in human malignancies can be utilized as a prognostic marker for patients. However, the prognostic value of miR-650 in human glioma has not been investigated yet. In the present investigation, we have recruited 168 cases glioma specimens and 21 normal control brain specimens. Quantitative real-time PCR was carried out to investigate the expression of miR-650. Kaplan-Meier analysis and Cox's proportional hazards model was used to evaluate the association of miR-650 with prognosis of glioma patients. Results showed that miR-650 expression was increased in glioma compared with normal control specimens (P < 0.001). It was also found that miR-650 expression was related to World Health Organization grade and Karnofsky performance score (KPS) for high expression was more frequently detected in glioma of high grade or low KPS score (P < 0.001). The prognosis of glioma with high miR-650 expression was significantly worse compared with that of glioma with low miR-650 expression. These results proved that miR-650 expression was a significant prognostic indicator in glioma, which may suggest new management of human glioma.

Decreased expression of NDRG2 is related to poor overall survival in patients with glioma.

Members of the NDRG (N-Myc downstream-regulated) gene family have been shown to play a variety of roles in human malignancies. In the present study, we examined the expression of NDRG2 protein in glioma samples of WHO grades I-IV. We also investigated the association between NDRG2 expression and survival. Immunohistochemical analysis was used to measure NDRG2 protein expression in 316 specimens of human glioma and 41 normal control tissues. Survival analysis was performed using the Kaplan-Meier method and Cox's proportional hazards model. We found that NDRG2 expression was reduced in glioma relative to normal tissue, and that NDRG2 expression decreased with increasing glioma grade. Kaplan-Meier analysis showed that patients without NDRG2 expression had a lower survival rate than other patients. Multivariate analysis showed that NDRG2 expression was an independent prognostic factor for overall survival of patients with glioma. The present study provides the first evidence that NDRG2 expression is decreased in gliomas, indicating that NDRG2 may play an inhibitory role during the development of gliomas. NDRG2 expression may also be a significant and independent prognostic indicator for glioma.

Decreased expression of NDRG1 in glioma is related to tumor progression and survival of patients.

The aim of the study was to examine the expression of NDRG1 gene in glioma samples with different WHO grades and its association with survival. About 168 glioma specimens and 21 normal control tissues were collected. Immunochemistry assay, quantitative real-time PCR and Western blot analysis were carried out to investigate the expression of NDRG1 and Myc. Kaplan-Meier method and Cox's proportional hazards model were used in survival analysis. Immunohistochemistry showed that Ndrg1 expression was reduced in glioma. NDRG1 mRNA and protein levels were lower in glioma compared to control on real-time PCR and Western blot analysis (P < 0.001). Its expression levels increase from grade IV to grade I glioma on real-time PCR, immunohistochemistry analysis (P < 0.001) and Western blot. On the contrary, the expression of Myc by real-time PCR and Western blot showed the opposite trend of NDRG1. The survival rate of Ndrg1-negative patients was lower than that of Ndrg1-positive patients. We confirmed that the loss of NDRG1 expression was a significant and independent prognostic indicator in glioma by multivariate analysis. NDRG1 may play an inhibitory role during the development of glioma and may be a potential prognosis predictor of glioma.