气化温度是影响生物质气化性能的重要参数,而工业气化炉内温度分布不均匀,阻碍了生物质高效气化的发展进程。为了预防或减少温度分布不均所造成的不良影响,提高生物质气化性能,通过实验方法研究了炉内温度梯度(axial temperature gradie...气化温度是影响生物质气化性能的重要参数,而工业气化炉内温度分布不均匀,阻碍了生物质高效气化的发展进程。为了预防或减少温度分布不均所造成的不良影响,提高生物质气化性能,通过实验方法研究了炉内温度梯度(axial temperature gradient,ATG)对生物质气化三相产物的影响。实验设定落下床的上段炉温为1300℃不变,下段炉温范围为900℃~1300℃以模拟工业气化炉火焰区存在的轴向温度梯度,以碳转化率和冷煤气效率为评价指标,对松木屑的气化特性进行了实验分析。结果表明:在ATG为100℃~300℃范围内,合成气中有效气体(CO+H_(2))产率、碳转化率和冷煤气效率随着ATG的增大而逐渐减小。半焦产率均低于0.2%,表明松木屑在上段炉(450 mm)1300℃高温区域内几乎实现了半焦的完全气化。碳烟为生物质高温气流床气化的主要含碳固体产物,其产率为半焦产率的3~6倍,且难以被完全清除。当上下两段的ATG高于300℃时,气相均相重整和气-固非均相反应在下段低温区几乎停滞,产物产率、碳转化率和冷煤气效率几乎保持不变,同时有少量焦油生成,占比约0.01%。展开更多
BACKGROUND Colorectal cancer(CRC)is among the most prevalent and life-threatening malignancies worldwide.Syndecan-2 methylation(mSDC2)testing has emerged as a widely used biomarker for early detection of CRC in stool ...BACKGROUND Colorectal cancer(CRC)is among the most prevalent and life-threatening malignancies worldwide.Syndecan-2 methylation(mSDC2)testing has emerged as a widely used biomarker for early detection of CRC in stool and serum samples.Cancer(CRC)is among the most prevalent and life-threatening malignancies worldwide.mSDC2 testing has emerged as a widely used biomarker for early detection of CRC in stool and serum samples.AIM To validate the effectiveness of fecal DNA mSDC2 testing in the detection of CRC among a high-risk Chinese population to provide evidence-based data for the development of diagnostic and/or screening guidelines for CRC in China.METHODS A high-risk Chinese cohort consisting of 1130 individuals aged 40-79 years was selected for evaluation via fecal mSDC2 testing.Sensitivity and specificity for CRC,advanced adenoma(AA)and advanced colorectal neoplasia(ACN)were determined.High-risk factors for the incidence of colorectal lesions were determined and a logistic regression model was constructed to reflect the efficacy of the test.RESULTS A total of 1035 high-risk individuals were included in this study according to established criteria.Among them,16 suffered from CRC(1.55%),65 from AA(6.28%)and 189 from non-AAs(18.26%);150 patients were diagnosed with polyps(14.49%).Diagnoses were established based upon colonoscopic and pathological examinations.Sensitivities of the mSDC2 test for CRC and AA were 87.50%and 40.00%,respectively;specificities were 95.61%for other groups.Positive predictive values of the mSDC2 test for CRC,AA and ACN were 16.09%,29.89%and 45.98%,respectively;the negative predictive value for CRC was 99.79%.After adjusting for other high-risk covariates,mSDC2 test positivity was found to be a significant risk factor for the occurrence of ACN(P<0.001).CONCLUSION Our findings confirmed that offering fecal mSDC2 testing and colonoscopy in combination for CRC screening is effective for earlier detection of malignant colorectal lesions in a high-risk Chinese population.展开更多
A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or dep...A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or deployable. However, compared with a fixed-bottom installation, FOWT has to suffer more extreme loads due to its extra degrees of freedom. Therefore, the stability of an FOWT is a key challenge in exploiting offshore deep-water wind. Focusing on the stability of barge-type FOWT, this paper is to investigate the effect of passive structural control by equipping a tuned mass damper (TMD) on the nacelle. The turbulent wind with sharp fluctuations is established both in velocity and inflow direction based on standard Kaimal turbulence spectrum as suggested in the standard IEC61400-2. The irregular wave is generated according to the Pierson-Moskowitz spectrum. The dynamic structural characteristics of FOWT are calculated based on the fully coupled aero-hydro-servo-elastic solver FAST. Evidence has shown that the proposed method of the nacelle-based TMD is effective in controlling stability of an FOWT, as the sway and roll motions of barge and the side-side displacement of tower top decreased significantly. With the increase of mass, the side-side displacement of tower-top and the amplitude of roll motion of barge reveal a trend of increasing first and then decreasing. The stiffness and damping have little effect. Furthermore, the multi-island genetic optimization algorithm (MIGA) is employed to find globally optimum structural parameters (mass, stiffness and damping) of the TMD. The optimum structure parameters of TMD are achieved when the mass is 21393 kg, damping is 13635 N/(m/s) and stiffness is 6828 N/m. By adopting the optimized TMD, stability of roll motion of barge and side-side displacement of tower-top increase up to 53% and 50% respectively when compared with the normal TMD. The simulation results verify the validity and reliability of the proposed TMD control and the optimization methods.展开更多
A series of CuO/ZnO/Al_2O_3, CuO/ZnO/ZrO_2/Al_2O_3 and CuO/ZnO/CeO_2/Al_2O_3 catalysts were prepared by coprecipitation and characterized by N_2 adsorption, XRD, TPR, N_2O titration and HRTEM. The catalytic performanc...A series of CuO/ZnO/Al_2O_3, CuO/ZnO/ZrO_2/Al_2O_3 and CuO/ZnO/CeO_2/Al_2O_3 catalysts were prepared by coprecipitation and characterized by N_2 adsorption, XRD, TPR, N_2O titration and HRTEM. The catalytic performances of these catalysts for the steam reforming of methanol were evaluated in a laboratory-scale fixed-bed reactor at 0.1 MPa and temperatures between 473 and 543 K. The results showed that the catalytic activity depended greatly on the catalyst reducibility and the specific surface area of Cu. An approximate linear correlation between the catalytic activity and the Cu surface area was found for all catalysts investigated in this study.Compared to CuO/ZnO/Al_2O_3, the ZrO_2-doped CuO/ZnO/Al_2O_3 exhibited higher activity and selectivity to CO,while the CeO_2-doped catalyst displayed lower activity and selectivity. Finally, an intrinsic kinetic study was carried out over a screened CuO/ZnO/CeO_2/Al_2O_3 catalyst in the absence of internal and external mass transfer effects. A good agreement was observed between the model-derived effluent concentrations of CO(CO_2) and the experimental data. The activation energies for the reactions of methanol-steam reforming, water-gas shift and methanol decomposition over CuO/ZnO/CeO_2/Al_2O_3 were 93.1, 85.1 and 116.5 k J·mol^(-1), respectively.展开更多
文摘气化温度是影响生物质气化性能的重要参数,而工业气化炉内温度分布不均匀,阻碍了生物质高效气化的发展进程。为了预防或减少温度分布不均所造成的不良影响,提高生物质气化性能,通过实验方法研究了炉内温度梯度(axial temperature gradient,ATG)对生物质气化三相产物的影响。实验设定落下床的上段炉温为1300℃不变,下段炉温范围为900℃~1300℃以模拟工业气化炉火焰区存在的轴向温度梯度,以碳转化率和冷煤气效率为评价指标,对松木屑的气化特性进行了实验分析。结果表明:在ATG为100℃~300℃范围内,合成气中有效气体(CO+H_(2))产率、碳转化率和冷煤气效率随着ATG的增大而逐渐减小。半焦产率均低于0.2%,表明松木屑在上段炉(450 mm)1300℃高温区域内几乎实现了半焦的完全气化。碳烟为生物质高温气流床气化的主要含碳固体产物,其产率为半焦产率的3~6倍,且难以被完全清除。当上下两段的ATG高于300℃时,气相均相重整和气-固非均相反应在下段低温区几乎停滞,产物产率、碳转化率和冷煤气效率几乎保持不变,同时有少量焦油生成,占比约0.01%。
基金Supported by the Science and Technology Program of Panyu Central Hospital,No.PY-2023-003the Science and Technology Program of Panyu,No.2020-Z04-054+4 种基金the Science and Technology Project of the Guangzhou Health Commission,No.20211A011114the Science and Technology Program of Guangzhou,No.202002020023the General University Youth Innovative Talent Project of Guangdong Province,No.2022KQNCX281the Guangdong Provincial Key Field Special Project for Ordinary Colleges and Universities,No.2023ZDZX2097the Foshan Engineering Technology Research Center for Prepared Food Processing and Quality Evaluation,No.2022-KJZX113.
文摘BACKGROUND Colorectal cancer(CRC)is among the most prevalent and life-threatening malignancies worldwide.Syndecan-2 methylation(mSDC2)testing has emerged as a widely used biomarker for early detection of CRC in stool and serum samples.Cancer(CRC)is among the most prevalent and life-threatening malignancies worldwide.mSDC2 testing has emerged as a widely used biomarker for early detection of CRC in stool and serum samples.AIM To validate the effectiveness of fecal DNA mSDC2 testing in the detection of CRC among a high-risk Chinese population to provide evidence-based data for the development of diagnostic and/or screening guidelines for CRC in China.METHODS A high-risk Chinese cohort consisting of 1130 individuals aged 40-79 years was selected for evaluation via fecal mSDC2 testing.Sensitivity and specificity for CRC,advanced adenoma(AA)and advanced colorectal neoplasia(ACN)were determined.High-risk factors for the incidence of colorectal lesions were determined and a logistic regression model was constructed to reflect the efficacy of the test.RESULTS A total of 1035 high-risk individuals were included in this study according to established criteria.Among them,16 suffered from CRC(1.55%),65 from AA(6.28%)and 189 from non-AAs(18.26%);150 patients were diagnosed with polyps(14.49%).Diagnoses were established based upon colonoscopic and pathological examinations.Sensitivities of the mSDC2 test for CRC and AA were 87.50%and 40.00%,respectively;specificities were 95.61%for other groups.Positive predictive values of the mSDC2 test for CRC,AA and ACN were 16.09%,29.89%and 45.98%,respectively;the negative predictive value for CRC was 99.79%.After adjusting for other high-risk covariates,mSDC2 test positivity was found to be a significant risk factor for the occurrence of ACN(P<0.001).CONCLUSION Our findings confirmed that offering fecal mSDC2 testing and colonoscopy in combination for CRC screening is effective for earlier detection of malignant colorectal lesions in a high-risk Chinese population.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51676131 and 51176129)the Innovation Key Program of Shanghai Municipal Education Commission(Grant Nos.13YZ066 and 13ZZ120)the Doctoral Fund of Ministry of Education of China(Grant No.20123120110008)
文摘A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or deployable. However, compared with a fixed-bottom installation, FOWT has to suffer more extreme loads due to its extra degrees of freedom. Therefore, the stability of an FOWT is a key challenge in exploiting offshore deep-water wind. Focusing on the stability of barge-type FOWT, this paper is to investigate the effect of passive structural control by equipping a tuned mass damper (TMD) on the nacelle. The turbulent wind with sharp fluctuations is established both in velocity and inflow direction based on standard Kaimal turbulence spectrum as suggested in the standard IEC61400-2. The irregular wave is generated according to the Pierson-Moskowitz spectrum. The dynamic structural characteristics of FOWT are calculated based on the fully coupled aero-hydro-servo-elastic solver FAST. Evidence has shown that the proposed method of the nacelle-based TMD is effective in controlling stability of an FOWT, as the sway and roll motions of barge and the side-side displacement of tower top decreased significantly. With the increase of mass, the side-side displacement of tower-top and the amplitude of roll motion of barge reveal a trend of increasing first and then decreasing. The stiffness and damping have little effect. Furthermore, the multi-island genetic optimization algorithm (MIGA) is employed to find globally optimum structural parameters (mass, stiffness and damping) of the TMD. The optimum structure parameters of TMD are achieved when the mass is 21393 kg, damping is 13635 N/(m/s) and stiffness is 6828 N/m. By adopting the optimized TMD, stability of roll motion of barge and side-side displacement of tower-top increase up to 53% and 50% respectively when compared with the normal TMD. The simulation results verify the validity and reliability of the proposed TMD control and the optimization methods.
基金Supported by the National Natural Science Foundation of China(21276076)the Program for New Century Excellent Talents in University(NCET-13-0801)the"111"Project(B08021)
文摘A series of CuO/ZnO/Al_2O_3, CuO/ZnO/ZrO_2/Al_2O_3 and CuO/ZnO/CeO_2/Al_2O_3 catalysts were prepared by coprecipitation and characterized by N_2 adsorption, XRD, TPR, N_2O titration and HRTEM. The catalytic performances of these catalysts for the steam reforming of methanol were evaluated in a laboratory-scale fixed-bed reactor at 0.1 MPa and temperatures between 473 and 543 K. The results showed that the catalytic activity depended greatly on the catalyst reducibility and the specific surface area of Cu. An approximate linear correlation between the catalytic activity and the Cu surface area was found for all catalysts investigated in this study.Compared to CuO/ZnO/Al_2O_3, the ZrO_2-doped CuO/ZnO/Al_2O_3 exhibited higher activity and selectivity to CO,while the CeO_2-doped catalyst displayed lower activity and selectivity. Finally, an intrinsic kinetic study was carried out over a screened CuO/ZnO/CeO_2/Al_2O_3 catalyst in the absence of internal and external mass transfer effects. A good agreement was observed between the model-derived effluent concentrations of CO(CO_2) and the experimental data. The activation energies for the reactions of methanol-steam reforming, water-gas shift and methanol decomposition over CuO/ZnO/CeO_2/Al_2O_3 were 93.1, 85.1 and 116.5 k J·mol^(-1), respectively.
