随着近几年来大量高压直流输电工程接入交流系统,给交直流混联电网带来重要影响,直流系统的运行状况,尤其是其控制保护系统的性能,已成为影响交直流混联电网安全稳定的重要因素。系统故障引发平波电抗器瓦斯保护误动作是导致直流系统闭...随着近几年来大量高压直流输电工程接入交流系统,给交直流混联电网带来重要影响,直流系统的运行状况,尤其是其控制保护系统的性能,已成为影响交直流混联电网安全稳定的重要因素。系统故障引发平波电抗器瓦斯保护误动作是导致直流系统闭锁的重要非电气量因素之一,该文详细研究分析了平抗瓦斯的设备原理和特点,采用Gaussian回归算法对平抗瓦斯机械振动与冲击电流的非线性耦合特性进行精细化模拟和解耦,且与电磁暂态算法相兼容,并基于国网仿真中心华东电网电力系统全数字实时仿真装置(advanced digital power system simulator,ADPSS)纯电磁暂态实际工程控保算例进行交直流电网纯电磁仿真,可以详细描述交直流电网故障冲击电流等电气量动态变化对平抗瓦斯机械振动加速度非电气量的非线性快速响应动态特性,为实际工程中多次发生的平抗瓦斯误动导致直流闭锁的事故分析和故障重演、预防及设备改进提供关键技术手段,对进一步提高直流实用化工程仿真的多维度精度具有重要现实意义,并为其他非线性电气相关设备的详细建模提供思路。展开更多
To facilitate rapid analysis of the oscillation stability mechanism in modular multilevel converter-based high voltage direct current(MMC-HVDC)systems and streamline the simulation process for determining MMC impedanc...To facilitate rapid analysis of the oscillation stability mechanism in modular multilevel converter-based high voltage direct current(MMC-HVDC)systems and streamline the simulation process for determining MMC impedance characteristics,a simplified mathematical simulation model for MMC closed-loop impedance is developed using the harmonic state space method.This model considers various control strategies and includes both AC-side and DC-side impedance models.By applying a Nyquist criterion-based impedance analysis method,the stability mechanisms on the AC and DC sides of the MMC are examined.In addition,a data-driven oscillation stability analysis method is also proposed,leveraging a global sensitivity algorithm based on fast model results to identify key parameters influencing MMC oscillation stability.Based on sensitivity analysis results,a parameter adjustment strategy for oscillation suppression is proposed.The simulation results from the MATLAB/Simulinkbased MMC model validate the effectiveness of the proposed method.展开更多
To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on ...To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on the two test walls, respectively. Then, the lateral load-top displacement curves, load beating capacity, ductility, lateral stiffness, strains of steel bars, strain distribution on the connecting steel frame (CSF), and relative slippages between the CSF and embedded limbic steel frame (ELSF) were discussed in detail. The test results show that the load bearing capacity and ductility of the test wall are both favorable with a displacement ductility factor of more than 3.7. The normal and shear stresses in the CSF except for the compression end are far smaller than the yield stresses throughout the test procedure. Certain slippages of about 1.13 mm occurs between the CSF and ELSF on the compression side of the test wall, while almost no slippages occurs on the tension side. The seismic performance of the test wall is favorable and the new-type scheme of the horizontal joints is both feasible and reliable.展开更多
A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexica...A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.展开更多
In order to improve the early-age cracking resistance of concrete, different types of superplasticizers are used. Two types of polycarboxlic salt/acid superplasticizers and one retarding naphthalene superplasticizer a...In order to improve the early-age cracking resistance of concrete, different types of superplasticizers are used. Two types of polycarboxlic salt/acid superplasticizers and one retarding naphthalene superplasticizer are selected to investigate the influence of superplasticizers on the early-age cracking resistance of the concrete by using the slab test and the temperature-stress test. The results show that the polycarboxlic salt/acid superplasticizer cannot always improve the cracking resistance capacity of the concrete compared with the naphthalene superplasticizer, which is related to the chemical structure of the polycarboxlic salt/acid superplasticizer. High plastic tensile strength and dynamic elastic modulus at the early stage are beneficial to avoid cracking, and low hydration heat is also helpful. The evolutions of the drying shrilakage stress and the hydration heat temperature stress varying with time can be comprehensively evaluated by means of the slab test and the temperature stress test.展开更多
A 13bit,pipelined analog-to-digital converter (ADC) designed to achieve high linearity is described. The high linearity is realized by using the passive capacitor error-averaging technique to calibrate the capacitor...A 13bit,pipelined analog-to-digital converter (ADC) designed to achieve high linearity is described. The high linearity is realized by using the passive capacitor error-averaging technique to calibrate the capacitor mismatch error, a gain-boosting opamp to minimize the finite gain error and gain nonlinearity,a bootstrapping switch to reduce the switch on-resistor nonlinearity, and an anti-disturb design to reduce the noise from the digital supply. This ADC is implemented in 0.18μm CMOS technology and occupies a die area of 3.2mm^2 , including pads. Measured performance includes - 0.18/ 0.15LSB of differential nonlinearity, -0.35/0.5LSB of integral nonlinearity, 75.7dB of signal-to-noise plus distortion ratio (SNDR) and 90. 5 dBc of spurious-free dynamic range (SFDR) for 2.4MHz input at 2.5MS/s. At full speed conversion (5MS/s) and for the same 2.4MHz input, the measured SNDR and SFDR are 73.7dB and 83.9 dBc, respectively. The power dissipation including output pad drivers is 21mW at 2.5MS/s and 34mW at 5MS/s,both at 2.7V supply.展开更多
Dishevelled (Dvl) is a highly conserved protein family that plays an important role in mediating Wnt signal- ing from membrane to cytoplasm. Recently we reported that Dvl also functions in the nucleus by stabilizing...Dishevelled (Dvl) is a highly conserved protein family that plays an important role in mediating Wnt signal- ing from membrane to cytoplasm. Recently we reported that Dvl also functions in the nucleus by stabilizing the β-catenin/TCFs transcriptional complex. Here we describe that Dvl may function as a repressor of NF-kB. Our data show that Dvl directly binds to p65 and their interaction occurs in the nucleus. Dvl expression inhibits p65-mediated or TNF-α-stimulated activation of the NF-KB dependent reporter. This action of Dvl, however, is not dependent on Wnt or its downstream effector β-catenin. Chromatin immunoprecipitation assay shows that recruitment of p65 to the promoters of NF-KB target genes is significantly enhanced when expression of Dvl is knocked down. Consistently, the expression level of a subset of NF-KB target genes is also increased after knock-down of Dvl. Moreover, our data suggest that Dvl may relieve the anti-apoptotic effect of NF-KB, thus play a role in promoting apoptosis. Therefore, this work demonstrates a novel function of Dvl in modulating NF-KB-regulated gene transcription.展开更多
Objectives: To measure serum and follicular resistin, steroids hormone levels in women with PCOS (polycystic ovary syndrome) (BMI (body mass index)<25 kg/m2), to assess possible correlations of resistin to hormonal...Objectives: To measure serum and follicular resistin, steroids hormone levels in women with PCOS (polycystic ovary syndrome) (BMI (body mass index)<25 kg/m2), to assess possible correlations of resistin to hormonal and metabolic parameters and to analyze the clinical outcomes of in vitro fertilization-embryo transfer (IVF-ET) in women with PCOS and tubal infertility. Study design: We analyzed the clinical outcomes of IVF-ET in women with PCOS (BMI<25 kg/m2) and tubal infertility during the years 2002 to 2004 and compared the serum and follicular fluid resistin levels, estradiol (E2), progesterone (P), testosterone (T) levels in 20 PCOS and 20 healthy, age-matched women without PCOS during IVF-stimulated cycles. The correlations between the resistin levels and the outcomes of IVF-ET were evaluated. Results: No significant differences in resistin levels of either serum or follicular fluid between PCOS and control group were found. However, resistin levels in serum were higher than that in follicular fluid in both groups. Multiple regression analysis showed that resistin levels in serum did not correlate with BMI, estradiol, LH (luteinizing hormone) and insulin level in fasting blood. No significant correlations were found between follicular fluid reisistin levels and fertilization rate, implantation rate, clinical pregnancy rate or early miscarriage rate in both PCOS and control groups. Conclusion: Our results show that resistin does not have correlation with the hormonal and metabolic parameters as well as the outcomes of IVF. These data suggest that resistin is unlikely to be a local determinant factor in steroidogenesis and growth and maturation of oocytes during IVF-ET in lean women with PCOS.展开更多
To determine how the auto-antibodies (Abs) profiles overlap in chronic hepatitis C infection (CHC) and autoimmune hepatitis (AIH) and correlate to liver disease.METHODSLevels of antinuclear Ab, smooth muscle antibody ...To determine how the auto-antibodies (Abs) profiles overlap in chronic hepatitis C infection (CHC) and autoimmune hepatitis (AIH) and correlate to liver disease.METHODSLevels of antinuclear Ab, smooth muscle antibody (SMA) and liver/kidney microsomal-1 (LKM-1) Ab and markers of liver damage were determined in the sera of 50 patients with CHC infection, 20 AIH patients and 20 healthy controls using enzyme linked immunosorbent assay and other immune assays.RESULTSWe found that AIH patients had more severe liver disease as determined by elevation of total IgG, alkaline phosphatase, total serum bilirubin and serum transaminases and significantly higher prevalence of the three non-organ-specific autoantibodies (auto-Abs) than CHC patients. Antinuclear Ab, SMA and LKM-1 Ab were also present in 36% of CHC patients and related to disease severity. CHC cases positive for auto-Abs were directly comparable to AIH in respect of most markers of liver damage and total IgG. These cases had longer disease duration compared with auto-Ab negative cases, but there was no difference in gender, age or viral load. KLM-1<sup>+</sup> Ab CHC cases showed best overlap with AIH.CONCLUSIONAuto-Ab levels in CHC may be important markers of disease severity and positive cases have a disease similar to AIH. Auto-Abs might have a pathogenic role as indicated by elevated markers of liver damage. Future studies will unravel any novel associations between these two diseases, whether genetic or other.展开更多
To properly simulate hard rock with a high ratio of the uniaxial compressive strength to tensile strength(UCS/TS) and realistic strength-failure envelope,the rock deformation and mechanical characteristics were discus...To properly simulate hard rock with a high ratio of the uniaxial compressive strength to tensile strength(UCS/TS) and realistic strength-failure envelope,the rock deformation and mechanical characteristics were discussed in detail when the particle simulation method with the clump parallel-bond model(CPBM) was used to conduct a series of numerical experiments at the specimen scale.Meanwhile,the effects of the loading procedure and crack density on the mechanical behavior of a specimen,which was modeled by the particle simulation method with the CPBM,were investigated.The related numerical results have demonstrated that:1) The uniaxial compressive strength(UCS),tensile strength(TS) and elastic modulus are overestimated when the conventional loading procedure is used in the particle simulation method with the CPBM; 2) The elastic modulus,strength and UCS/TS decrease,while Poisson ratio increases with the increase of the crack density in the particle simulation method with the CPBM; 3) The particle simulation method with the CPBM can be used to reproduce a high value of UCS/TS(>10),as well as a high friction angle and reasonable cohesion strength; 4) As the confining pressure increases,both the peak strength of the simulated specimen and the number of microscopic cracks increase,but the ratio of tensile cracks number to shear cracks number decreases in the particle simulation method with the CPBM; 5) Compared with the conventional parallel-bond model,the CPBM can be used to reproduce more accurate results for simulating the rock deformation and mechanical characteristics.展开更多
A novel dual-band planar microstrip filter using parallel coupled microstrip lines and open-loop stepped-impedance resonators(SIRs)loaded with two shunt open stubs is presented.By tuning the physical lengths of open...A novel dual-band planar microstrip filter using parallel coupled microstrip lines and open-loop stepped-impedance resonators(SIRs)loaded with two shunt open stubs is presented.By tuning the physical lengths of open-loop SIRs,parallel coupled microstrip lines and two stubs,the bandpass filter has good dual-passband performance at 2.55 and 5.35 GHz and high isolation between the two passbands.The relative bandwidths of the two passbands are 11.8% and 16.8%,respectively.Compared with the conventional open-loop SIR filters,the designed filter has a comparatively broader fractional bandwidth at the second passband.So it can cover all the wireless LAN(local area network)bands.In addition,the filter has the features of low loss,high rejection and low ripple.The measured results are in good agreement with the simulated responses by HFSS software.展开更多
A new method based on the multi-wedge translation mechanism is presented to calculate the lateral force acting on the stabilizing piles. At first, there is no assumption for the shape of potential sliding surface, it ...A new method based on the multi-wedge translation mechanism is presented to calculate the lateral force acting on the stabilizing piles. At first, there is no assumption for the shape of potential sliding surface, it is just considered that the potential sliding surface is a composite of a number of straight lines. And then, the potential sliding mass is divided into a number of triangular wedges take with these straight lines as its base. The kinematic theorem of limit analysis is adopted to calculate the rate of external work and the rate of energy dissipation for each triangular wedge, respectively. Furthermore, the multivariate functions are established to calculate the lateral force acting on the stabilizing piles. The lateral force and the corresponding potential sliding surfaces can be obtained by an optimizational technique. At last, an example is taken to illustrate the method. The effect of soil strength parameters, slope angle and pile roughness on the lateral force and the corresponding potential sliding surface are analyzed.The result are compared with those obtained using other methods.展开更多
The effect of N levels and sources on the antioxidant components in vegetable is not completely understood. Therefore, greenhouse experiments were conducted to determine the changes in antioxidant capacity diphenyl-2-...The effect of N levels and sources on the antioxidant components in vegetable is not completely understood. Therefore, greenhouse experiments were conducted to determine the changes in antioxidant capacity diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP), total phenolics, ascorbic acid, total carotene and lycopene contents in edible portions of lettuce, onion and tomato due to different nitrogen levels and sources. The experiment included three N levels (20, 40 and 60 kg/ha for lettuce trial and 60, 120 and 180 kg/ha for either onion or tomato) and four nitrogen sources (calcium nitrate, ammonium sulphate, ammonium nitrate and urea). The antioxidant capacity and phenolic contents in lettuce was enhanced under low nitrogen level, while the antioxidant capacities, phenolics, carotenoids and lycopene in tomato fruits were not significantly affected by the nitrogen dose applied. Application of calcium nitrate caused 50% increase in DPPH and 20% in FRAP of lettuce compared to other nitrogen forms. Tomato treated with calcium nitrate or ammonium sulphate had higher phenolic and ascorbic acid contents than treated plants with ammonium nitrate or urea. Antioxidant tested parameters of onion were not significantly affected by the nitrogen treatments. Nitrogen concentration in tomato fruits significantly correlated with FRAP antioxidant capacity, phenolics, ascorbic acid, carotene and lycopene contents.展开更多
AIM:To investigate the clinical implications of lipid deposition in the pancreas(fatty pancreas). METHODS:The subjects of this study were 293 patients who had undergone abdominal computed tomography(CT)and sonography....AIM:To investigate the clinical implications of lipid deposition in the pancreas(fatty pancreas). METHODS:The subjects of this study were 293 patients who had undergone abdominal computed tomography(CT)and sonography.Fatty pancreas was diagnosed by sonographic findings and subdivided into mild,moderate,and severe fatty pancreas groups comparing to the retroperitoneal fat echogenicity. RESULTS:Fatty pancreas was associated with higher levels for visceral fat,waist circumference,aspartate aminotransferase(AST),alanine aminotransferase (ALT),total cholesterol,triglyceride,high density lipoprotein,free fatty acid,γ-GTP,insulin,and the homeostasis model assessment of insulin resistance (HOMA-IR)than the control group(P<0.05).HOMAIR,visceral fat,triglyceride,and ALT also tended to increase with the degree of fat deposition in the pancreas on sonography.In a multivariate logistic regression analysis,HOMA-IR,visceral fat,and ALT level were independently related to fatty pancreas after adjustment for age,body mass index,and lipid profile.The incidence of metabolic syndrome in the fatty pancreas group was significantly higher than in the control group,and the numbers of metabolic syndrome parameters were significantly higher in the fatty pancreas group(P<0.05).CONCLUSION:Sonographic fatty pancrease showed higher insulin resistance,visceral fat area,triglyceride, and ALT levels than normal pancreases.Fatty pancreas also showed a strong correlation with metabolic syndrome.展开更多
The World Health Organization (WHO) standard assay for determining levels of the rabies virus neutralization antibody (RVNA) is the rapid fluorescent focus inhibition test (RFFIT), which is used to evaluate the immuni...The World Health Organization (WHO) standard assay for determining levels of the rabies virus neutralization antibody (RVNA) is the rapid fluorescent focus inhibition test (RFFIT), which is used to evaluate the immunity effect after vaccination against rabies. For RFFIT, CVS-11 was used as the challenge virus, BSR cells as the adapted cells, and WHO rabies immunoglobulin (WHO STD) as the reference serum in this study. With reference to WHO and Pasteur RFFIT procedures, a micro-RFFIT procedure adapted to our laboratory was produced, and its specificity and reproducibility were tested. We tested levels of RVNA in human serum samples after immunization with different human rabies vaccines (domestic purified Vero cell rabies vaccine (PVRV) and imported purified chick embryo cell vaccine (PCECV)) using different regimens (Zagreb regimen and Essen regimen). We analyzed the levels of RVNA, and compared the immune efficacy of domestic PVRV and imported PCECV using different immunization regimens. The results showed that the immune efficacy of domestic PVRV using the Zagreb regimen was as good as that of the imported PCECV, but virus antibodies were generated more rapidly with the Zagreb regimen than with the Essen regimen. The RFFIT procedure established in our laboratory will enhance the comprehensive detection ability of institutions involved in rabies surveillance in China.展开更多
文摘随着近几年来大量高压直流输电工程接入交流系统,给交直流混联电网带来重要影响,直流系统的运行状况,尤其是其控制保护系统的性能,已成为影响交直流混联电网安全稳定的重要因素。系统故障引发平波电抗器瓦斯保护误动作是导致直流系统闭锁的重要非电气量因素之一,该文详细研究分析了平抗瓦斯的设备原理和特点,采用Gaussian回归算法对平抗瓦斯机械振动与冲击电流的非线性耦合特性进行精细化模拟和解耦,且与电磁暂态算法相兼容,并基于国网仿真中心华东电网电力系统全数字实时仿真装置(advanced digital power system simulator,ADPSS)纯电磁暂态实际工程控保算例进行交直流电网纯电磁仿真,可以详细描述交直流电网故障冲击电流等电气量动态变化对平抗瓦斯机械振动加速度非电气量的非线性快速响应动态特性,为实际工程中多次发生的平抗瓦斯误动导致直流闭锁的事故分析和故障重演、预防及设备改进提供关键技术手段,对进一步提高直流实用化工程仿真的多维度精度具有重要现实意义,并为其他非线性电气相关设备的详细建模提供思路。
基金National Natural Science Foundation of China(52307127)State Key Laboratory of Power System Operation and Control(SKLD23KZ07)。
文摘To facilitate rapid analysis of the oscillation stability mechanism in modular multilevel converter-based high voltage direct current(MMC-HVDC)systems and streamline the simulation process for determining MMC impedance characteristics,a simplified mathematical simulation model for MMC closed-loop impedance is developed using the harmonic state space method.This model considers various control strategies and includes both AC-side and DC-side impedance models.By applying a Nyquist criterion-based impedance analysis method,the stability mechanisms on the AC and DC sides of the MMC are examined.In addition,a data-driven oscillation stability analysis method is also proposed,leveraging a global sensitivity algorithm based on fast model results to identify key parameters influencing MMC oscillation stability.Based on sensitivity analysis results,a parameter adjustment strategy for oscillation suppression is proposed.The simulation results from the MATLAB/Simulinkbased MMC model validate the effectiveness of the proposed method.
文摘To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on the two test walls, respectively. Then, the lateral load-top displacement curves, load beating capacity, ductility, lateral stiffness, strains of steel bars, strain distribution on the connecting steel frame (CSF), and relative slippages between the CSF and embedded limbic steel frame (ELSF) were discussed in detail. The test results show that the load bearing capacity and ductility of the test wall are both favorable with a displacement ductility factor of more than 3.7. The normal and shear stresses in the CSF except for the compression end are far smaller than the yield stresses throughout the test procedure. Certain slippages of about 1.13 mm occurs between the CSF and ELSF on the compression side of the test wall, while almost no slippages occurs on the tension side. The seismic performance of the test wall is favorable and the new-type scheme of the horizontal joints is both feasible and reliable.
文摘A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.
基金International Collaborative Research Project of Sika Technology AG of Switzerland,the Traffic Scientific Research Project in Jiangsu Province (No. 2010Y01)
文摘In order to improve the early-age cracking resistance of concrete, different types of superplasticizers are used. Two types of polycarboxlic salt/acid superplasticizers and one retarding naphthalene superplasticizer are selected to investigate the influence of superplasticizers on the early-age cracking resistance of the concrete by using the slab test and the temperature-stress test. The results show that the polycarboxlic salt/acid superplasticizer cannot always improve the cracking resistance capacity of the concrete compared with the naphthalene superplasticizer, which is related to the chemical structure of the polycarboxlic salt/acid superplasticizer. High plastic tensile strength and dynamic elastic modulus at the early stage are beneficial to avoid cracking, and low hydration heat is also helpful. The evolutions of the drying shrilakage stress and the hydration heat temperature stress varying with time can be comprehensively evaluated by means of the slab test and the temperature stress test.
文摘A 13bit,pipelined analog-to-digital converter (ADC) designed to achieve high linearity is described. The high linearity is realized by using the passive capacitor error-averaging technique to calibrate the capacitor mismatch error, a gain-boosting opamp to minimize the finite gain error and gain nonlinearity,a bootstrapping switch to reduce the switch on-resistor nonlinearity, and an anti-disturb design to reduce the noise from the digital supply. This ADC is implemented in 0.18μm CMOS technology and occupies a die area of 3.2mm^2 , including pads. Measured performance includes - 0.18/ 0.15LSB of differential nonlinearity, -0.35/0.5LSB of integral nonlinearity, 75.7dB of signal-to-noise plus distortion ratio (SNDR) and 90. 5 dBc of spurious-free dynamic range (SFDR) for 2.4MHz input at 2.5MS/s. At full speed conversion (5MS/s) and for the same 2.4MHz input, the measured SNDR and SFDR are 73.7dB and 83.9 dBc, respectively. The power dissipation including output pad drivers is 21mW at 2.5MS/s and 34mW at 5MS/s,both at 2.7V supply.
基金This work was supported by the Ministry of Science and Technology of China (2010CB912100 and 2007CB914500), the National Natural Science Foundation of China (30821065, 30930052 and 90813024), and the Science and Technology Commission of Shanghai Municipality.
文摘Dishevelled (Dvl) is a highly conserved protein family that plays an important role in mediating Wnt signal- ing from membrane to cytoplasm. Recently we reported that Dvl also functions in the nucleus by stabilizing the β-catenin/TCFs transcriptional complex. Here we describe that Dvl may function as a repressor of NF-kB. Our data show that Dvl directly binds to p65 and their interaction occurs in the nucleus. Dvl expression inhibits p65-mediated or TNF-α-stimulated activation of the NF-KB dependent reporter. This action of Dvl, however, is not dependent on Wnt or its downstream effector β-catenin. Chromatin immunoprecipitation assay shows that recruitment of p65 to the promoters of NF-KB target genes is significantly enhanced when expression of Dvl is knocked down. Consistently, the expression level of a subset of NF-KB target genes is also increased after knock-down of Dvl. Moreover, our data suggest that Dvl may relieve the anti-apoptotic effect of NF-KB, thus play a role in promoting apoptosis. Therefore, this work demonstrates a novel function of Dvl in modulating NF-KB-regulated gene transcription.
文摘Objectives: To measure serum and follicular resistin, steroids hormone levels in women with PCOS (polycystic ovary syndrome) (BMI (body mass index)<25 kg/m2), to assess possible correlations of resistin to hormonal and metabolic parameters and to analyze the clinical outcomes of in vitro fertilization-embryo transfer (IVF-ET) in women with PCOS and tubal infertility. Study design: We analyzed the clinical outcomes of IVF-ET in women with PCOS (BMI<25 kg/m2) and tubal infertility during the years 2002 to 2004 and compared the serum and follicular fluid resistin levels, estradiol (E2), progesterone (P), testosterone (T) levels in 20 PCOS and 20 healthy, age-matched women without PCOS during IVF-stimulated cycles. The correlations between the resistin levels and the outcomes of IVF-ET were evaluated. Results: No significant differences in resistin levels of either serum or follicular fluid between PCOS and control group were found. However, resistin levels in serum were higher than that in follicular fluid in both groups. Multiple regression analysis showed that resistin levels in serum did not correlate with BMI, estradiol, LH (luteinizing hormone) and insulin level in fasting blood. No significant correlations were found between follicular fluid reisistin levels and fertilization rate, implantation rate, clinical pregnancy rate or early miscarriage rate in both PCOS and control groups. Conclusion: Our results show that resistin does not have correlation with the hormonal and metabolic parameters as well as the outcomes of IVF. These data suggest that resistin is unlikely to be a local determinant factor in steroidogenesis and growth and maturation of oocytes during IVF-ET in lean women with PCOS.
文摘To determine how the auto-antibodies (Abs) profiles overlap in chronic hepatitis C infection (CHC) and autoimmune hepatitis (AIH) and correlate to liver disease.METHODSLevels of antinuclear Ab, smooth muscle antibody (SMA) and liver/kidney microsomal-1 (LKM-1) Ab and markers of liver damage were determined in the sera of 50 patients with CHC infection, 20 AIH patients and 20 healthy controls using enzyme linked immunosorbent assay and other immune assays.RESULTSWe found that AIH patients had more severe liver disease as determined by elevation of total IgG, alkaline phosphatase, total serum bilirubin and serum transaminases and significantly higher prevalence of the three non-organ-specific autoantibodies (auto-Abs) than CHC patients. Antinuclear Ab, SMA and LKM-1 Ab were also present in 36% of CHC patients and related to disease severity. CHC cases positive for auto-Abs were directly comparable to AIH in respect of most markers of liver damage and total IgG. These cases had longer disease duration compared with auto-Ab negative cases, but there was no difference in gender, age or viral load. KLM-1<sup>+</sup> Ab CHC cases showed best overlap with AIH.CONCLUSIONAuto-Ab levels in CHC may be important markers of disease severity and positive cases have a disease similar to AIH. Auto-Abs might have a pathogenic role as indicated by elevated markers of liver damage. Future studies will unravel any novel associations between these two diseases, whether genetic or other.
基金Project(11272359) supported by the National Natural Science Foundation of China
文摘To properly simulate hard rock with a high ratio of the uniaxial compressive strength to tensile strength(UCS/TS) and realistic strength-failure envelope,the rock deformation and mechanical characteristics were discussed in detail when the particle simulation method with the clump parallel-bond model(CPBM) was used to conduct a series of numerical experiments at the specimen scale.Meanwhile,the effects of the loading procedure and crack density on the mechanical behavior of a specimen,which was modeled by the particle simulation method with the CPBM,were investigated.The related numerical results have demonstrated that:1) The uniaxial compressive strength(UCS),tensile strength(TS) and elastic modulus are overestimated when the conventional loading procedure is used in the particle simulation method with the CPBM; 2) The elastic modulus,strength and UCS/TS decrease,while Poisson ratio increases with the increase of the crack density in the particle simulation method with the CPBM; 3) The particle simulation method with the CPBM can be used to reproduce a high value of UCS/TS(>10),as well as a high friction angle and reasonable cohesion strength; 4) As the confining pressure increases,both the peak strength of the simulated specimen and the number of microscopic cracks increase,but the ratio of tensile cracks number to shear cracks number decreases in the particle simulation method with the CPBM; 5) Compared with the conventional parallel-bond model,the CPBM can be used to reproduce more accurate results for simulating the rock deformation and mechanical characteristics.
基金The National Natural Science Foundation of China(No.60621002,60702027,60921063)the National Basic Research Program of China(973Program)(No.2010CB327400)the National High Technology Research and Development Program of China(863Program)(No.2008ZX03005-001,2008AA01Z223,2009AA011503)
文摘A novel dual-band planar microstrip filter using parallel coupled microstrip lines and open-loop stepped-impedance resonators(SIRs)loaded with two shunt open stubs is presented.By tuning the physical lengths of open-loop SIRs,parallel coupled microstrip lines and two stubs,the bandpass filter has good dual-passband performance at 2.55 and 5.35 GHz and high isolation between the two passbands.The relative bandwidths of the two passbands are 11.8% and 16.8%,respectively.Compared with the conventional open-loop SIR filters,the designed filter has a comparatively broader fractional bandwidth at the second passband.So it can cover all the wireless LAN(local area network)bands.In addition,the filter has the features of low loss,high rejection and low ripple.The measured results are in good agreement with the simulated responses by HFSS software.
基金Projects(SKLGP2012K024,SKLGP2013K012)supported by the Opening Fund of State Key Laboratory of Geohazard Prevention and Ceoenvironment Protection,ChinaProject(2011BAK12B03)supported by the National Technology Project,ChinaProject(41401004)supported by the National Natural Science Foundation of China
文摘A new method based on the multi-wedge translation mechanism is presented to calculate the lateral force acting on the stabilizing piles. At first, there is no assumption for the shape of potential sliding surface, it is just considered that the potential sliding surface is a composite of a number of straight lines. And then, the potential sliding mass is divided into a number of triangular wedges take with these straight lines as its base. The kinematic theorem of limit analysis is adopted to calculate the rate of external work and the rate of energy dissipation for each triangular wedge, respectively. Furthermore, the multivariate functions are established to calculate the lateral force acting on the stabilizing piles. The lateral force and the corresponding potential sliding surfaces can be obtained by an optimizational technique. At last, an example is taken to illustrate the method. The effect of soil strength parameters, slope angle and pile roughness on the lateral force and the corresponding potential sliding surface are analyzed.The result are compared with those obtained using other methods.
文摘The effect of N levels and sources on the antioxidant components in vegetable is not completely understood. Therefore, greenhouse experiments were conducted to determine the changes in antioxidant capacity diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP), total phenolics, ascorbic acid, total carotene and lycopene contents in edible portions of lettuce, onion and tomato due to different nitrogen levels and sources. The experiment included three N levels (20, 40 and 60 kg/ha for lettuce trial and 60, 120 and 180 kg/ha for either onion or tomato) and four nitrogen sources (calcium nitrate, ammonium sulphate, ammonium nitrate and urea). The antioxidant capacity and phenolic contents in lettuce was enhanced under low nitrogen level, while the antioxidant capacities, phenolics, carotenoids and lycopene in tomato fruits were not significantly affected by the nitrogen dose applied. Application of calcium nitrate caused 50% increase in DPPH and 20% in FRAP of lettuce compared to other nitrogen forms. Tomato treated with calcium nitrate or ammonium sulphate had higher phenolic and ascorbic acid contents than treated plants with ammonium nitrate or urea. Antioxidant tested parameters of onion were not significantly affected by the nitrogen treatments. Nitrogen concentration in tomato fruits significantly correlated with FRAP antioxidant capacity, phenolics, ascorbic acid, carotene and lycopene contents.
文摘AIM:To investigate the clinical implications of lipid deposition in the pancreas(fatty pancreas). METHODS:The subjects of this study were 293 patients who had undergone abdominal computed tomography(CT)and sonography.Fatty pancreas was diagnosed by sonographic findings and subdivided into mild,moderate,and severe fatty pancreas groups comparing to the retroperitoneal fat echogenicity. RESULTS:Fatty pancreas was associated with higher levels for visceral fat,waist circumference,aspartate aminotransferase(AST),alanine aminotransferase (ALT),total cholesterol,triglyceride,high density lipoprotein,free fatty acid,γ-GTP,insulin,and the homeostasis model assessment of insulin resistance (HOMA-IR)than the control group(P<0.05).HOMAIR,visceral fat,triglyceride,and ALT also tended to increase with the degree of fat deposition in the pancreas on sonography.In a multivariate logistic regression analysis,HOMA-IR,visceral fat,and ALT level were independently related to fatty pancreas after adjustment for age,body mass index,and lipid profile.The incidence of metabolic syndrome in the fatty pancreas group was significantly higher than in the control group,and the numbers of metabolic syndrome parameters were significantly higher in the fatty pancreas group(P<0.05).CONCLUSION:Sonographic fatty pancrease showed higher insulin resistance,visceral fat area,triglyceride, and ALT levels than normal pancreases.Fatty pancreas also showed a strong correlation with metabolic syndrome.
基金National Department Public Benefit Research Foundation (201103032)
文摘The World Health Organization (WHO) standard assay for determining levels of the rabies virus neutralization antibody (RVNA) is the rapid fluorescent focus inhibition test (RFFIT), which is used to evaluate the immunity effect after vaccination against rabies. For RFFIT, CVS-11 was used as the challenge virus, BSR cells as the adapted cells, and WHO rabies immunoglobulin (WHO STD) as the reference serum in this study. With reference to WHO and Pasteur RFFIT procedures, a micro-RFFIT procedure adapted to our laboratory was produced, and its specificity and reproducibility were tested. We tested levels of RVNA in human serum samples after immunization with different human rabies vaccines (domestic purified Vero cell rabies vaccine (PVRV) and imported purified chick embryo cell vaccine (PCECV)) using different regimens (Zagreb regimen and Essen regimen). We analyzed the levels of RVNA, and compared the immune efficacy of domestic PVRV and imported PCECV using different immunization regimens. The results showed that the immune efficacy of domestic PVRV using the Zagreb regimen was as good as that of the imported PCECV, but virus antibodies were generated more rapidly with the Zagreb regimen than with the Essen regimen. The RFFIT procedure established in our laboratory will enhance the comprehensive detection ability of institutions involved in rabies surveillance in China.