The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al_(2)O_(3) whiskers in Mg matrix composites.The Mg powders were decorated with sodium dodecy...The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al_(2)O_(3) whiskers in Mg matrix composites.The Mg powders were decorated with sodium dodecylbenzene sulfonate(C_(18)H_(29)NaO_(3)S,SDBS)and were introduced to the cathode group on their surface.The Al_(2)O_(3) whiskers were modified by the cetyl trimethyl ammonium bromide(C_(19)H_(42)BrN,CTAB)and were featured in the anode group.The suitable contents of CTAB and SDBS,the application atmosphere,and the type of solvents were investigated.Dispersion results showed that adding 2wt%SDBS into Mg powders and adding 2wt%CTAB into Al_(2)O_(3) whiskers pro-moted the formation of more uniformly mixed composite powders,compared to those of conventional ball milling via scanning electron micro-scopy(SEM)analysis.Meanwhile,the calculated results derived from first-principle calculations also demonstrated the stronger cohesion between Al_(2)O_(3) whisker reinforcements and Mg matrix than undecorated composite powders.After preparation by powder metallurgy,the mor-phology,grain size,hardness,and standard deviation coefficient of composites were analyzed to evaluate the dispersed efficiency.The results indicated that the modification of homogenized dispersed Al_(2)O_(3) whiskers in composites contributed to the refinement of 26%in grain size and the improvement of 20%in hardness compared with pure Mg,and the reduction of 32.5%in the standard deviation coefficient of hardness compared with the ball-milling sample.展开更多
为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现...为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现,根据可控及可观格莱姆矩阵得到基于相似变换矩阵的L_(2)灵敏度表达式,并进行稀疏化校准,将L_(2)灵敏度最小化问题转换为凸函数求最值问题,求导得到L_(2)灵敏度最小化表达式,代回即得前向差分算子数字滤波器的稀疏化状态空间实现.仿真结果表明,所提方法设计的数字滤波器具有更好的抗FWL效应.展开更多
An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved....An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the? values from the extraction-experimentally obtained logKD,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, KD,Pic, denotes an individual distribution constant of Pic﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the? terms in their functional expressions.展开更多
The COVID-19 pandemic has revealed sex-based differences in anti-viral responses,with a higher rate of SARS-CoV-2 infections as well as a higher rate of morbidity and mortality in men than in women.Males and females a...The COVID-19 pandemic has revealed sex-based differences in anti-viral responses,with a higher rate of SARS-CoV-2 infections as well as a higher rate of morbidity and mortality in men than in women.Males and females also show disparate immune responses to COVID-19 infection,which may be important contributors to lower rates of infection,disease severity and deaths in women than in men.Here,the authors review sex differences in SARS-CoV-2 infections,anti-viral immunity and vaccine responses,putting forth the importance of sex,the underappreciated variables in vaccine response and disease infectivity.展开更多
Background: Metabolic syndrome (MS) is common among people with type 2 diabetes. The purpose of this study was to assess the proportion of MS and its individual components among type 2 diabetic adults, to stratify the...Background: Metabolic syndrome (MS) is common among people with type 2 diabetes. The purpose of this study was to assess the proportion of MS and its individual components among type 2 diabetic adults, to stratify these by gender and to determine their association with ischemic heart disease (IHD). Method: A cross-sectional multicentre study was conducted in public and private sector clinics in Karachi, Pakistan. A pretested structured questionnaire and medical records were used to collect information from 889 people with type 2 diabetes after informed consent. Chi-square test and odds ratios with 95% CI were used to assess the association of MS, its components and IHD. Adjusted odds ratios were used to evaluate the differences of MS and its components by gender. Results: In all, 70% of the participants had MS. The likelihood of having IHD among those with MS was higher (OR = 3.21;95%CI = 2.22 - 4.65). Of the individual MS components, obesity conferred the strongest association with IHD (OR = 2.57;95%CI = 1.91 - 3.43). Multivariate analysis showed an increased proportion of MS among women (AOR = 1.63;95%CI = 1.18 - 2.24). Of the individual MS components, women had a higher prevalence of obesity (AOR = 4.70;95%CI = 3.30 - 6.70). Conclusion: A very high burden of MS among type 2 diabetics has been identified in this study. Dedicated interventions are needed to prevent/delay the onset of MS and the associated morbidity and mortality.展开更多
In this paper,the forecasting equations of a 2nd-order space-time differential remainder are deduced from the Navier-Stokes primitive equations and Eulerian operator by Taylor-series expansion.Here we introduce a cubi...In this paper,the forecasting equations of a 2nd-order space-time differential remainder are deduced from the Navier-Stokes primitive equations and Eulerian operator by Taylor-series expansion.Here we introduce a cubic spline numerical model(Spline Model for short),which is with a quasi-Lagrangian time-split integration scheme of fitting cubic spline/bicubic surface to all physical variable fields in the atmospheric equations on spherical discrete latitude-longitude mesh.A new algorithm of"fitting cubic spline—time step integration—fitting cubic spline—……"is developed to determine their first-and2nd-order derivatives and their upstream points for time discrete integral to the governing equations in Spline Model.And the cubic spline function and its mathematical polarities are also discussed to understand the Spline Model’s mathematical foundation of numerical analysis.It is pointed out that the Spline Model has mathematical laws of"convergence"of the cubic spline functions contracting to the original functions as well as its 1st-order and 2nd-order derivatives.The"optimality"of the 2nd-order derivative of the cubic spline functions is optimal approximation to that of the original functions.In addition,a Hermite bicubic patch is equivalent to operate on a grid for a 2nd-order derivative variable field.Besides,the slopes and curvatures of a central difference are identified respectively,with a smoothing coefficient of 1/3,three-point smoothing of that of a cubic spline.Then the slopes and curvatures of a central difference are calculated from the smoothing coefficient 1/3 and three-point smoothing of that of a cubic spline,respectively.Furthermore,a global simulation case of adiabatic,non-frictional and"incompressible"model atmosphere is shown with the quasi-Lagrangian time integration by using a global Spline Model,whose initial condition comes from the NCEP reanalysis data,along with quasi-uniform latitude-longitude grids and the so-called"shallow atmosphere"Navier-Stokes primitive equations in the spherical coordinates.The Spline Model,which adopted the Navier-Stokes primitive equations and quasi-Lagrangian time-split integration scheme,provides an initial ideal case of global atmospheric circulation.In addition,considering the essentially non-linear atmospheric motions,the Spline Model could judge reasonably well simple points of any smoothed variable field according to its fitting spline curvatures that must conform to its physical interpretation.展开更多
Boundary procedure is an important phenomenon in numerical simulation. To reduce or eliminate the spurious reflections significantly which is occurred in boundary is a challenging and vital approach. The appropriate a...Boundary procedure is an important phenomenon in numerical simulation. To reduce or eliminate the spurious reflections significantly which is occurred in boundary is a challenging and vital approach. The appropriate artificial numerical boundaries can be applied to eliminate the effect of unnecessary spurious reflections in case of the numerical simulations of wave propagation phenomena problems. Typically, to reduce the artificial reflections, the absorbing boundary conditions are necessary. In this paper, we overview and investigate the appropriate typical absorbing boundary conditions and analyzed the boundary effect of two dimensional wave equation numerically. Reflections over the wide-ranging incident angles are complicated to eliminate, but the absorbing boundary conditions that we have applied are computationally cost efficient, easy to apply and able to reduce reflections significantly. For numerical solution, finite difference method is applied to develop numerical scheme using 2D wave equation. Using the developed numerical scheme, we obtain the numerical solution of the governing equation as an initial boundary value problem and realize the qualitative behavior of the solution in infinite space. The finite difference numerical scheme has been investigated by developing MATLAB programming language code. Numerical results have been discussed and analyzed with presenting different qualitative behavior of the numerical scheme. The accuracy and efficiency of the numerical scheme has been illustrated. The stability analysis was discussed and verified stability condition. Using the numerical scheme and absorbing boundary conditions, the boundary effects and absorption of spurious reflection of boundary have been demonstrated.展开更多
基金the Fundamental Research Funds for the National Natural Science Foundation of China (Nos. 52101123 and 52004227)the Fundamental Research Funds for the Central Universities-Interdisciplinary Research (No. 2682021ZTPY001)the Dongguan Scitech Commissioner (No. 20211800500102)
文摘The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al_(2)O_(3) whiskers in Mg matrix composites.The Mg powders were decorated with sodium dodecylbenzene sulfonate(C_(18)H_(29)NaO_(3)S,SDBS)and were introduced to the cathode group on their surface.The Al_(2)O_(3) whiskers were modified by the cetyl trimethyl ammonium bromide(C_(19)H_(42)BrN,CTAB)and were featured in the anode group.The suitable contents of CTAB and SDBS,the application atmosphere,and the type of solvents were investigated.Dispersion results showed that adding 2wt%SDBS into Mg powders and adding 2wt%CTAB into Al_(2)O_(3) whiskers pro-moted the formation of more uniformly mixed composite powders,compared to those of conventional ball milling via scanning electron micro-scopy(SEM)analysis.Meanwhile,the calculated results derived from first-principle calculations also demonstrated the stronger cohesion between Al_(2)O_(3) whisker reinforcements and Mg matrix than undecorated composite powders.After preparation by powder metallurgy,the mor-phology,grain size,hardness,and standard deviation coefficient of composites were analyzed to evaluate the dispersed efficiency.The results indicated that the modification of homogenized dispersed Al_(2)O_(3) whiskers in composites contributed to the refinement of 26%in grain size and the improvement of 20%in hardness compared with pure Mg,and the reduction of 32.5%in the standard deviation coefficient of hardness compared with the ball-milling sample.
文摘为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现,根据可控及可观格莱姆矩阵得到基于相似变换矩阵的L_(2)灵敏度表达式,并进行稀疏化校准,将L_(2)灵敏度最小化问题转换为凸函数求最值问题,求导得到L_(2)灵敏度最小化表达式,代回即得前向差分算子数字滤波器的稀疏化状态空间实现.仿真结果表明,所提方法设计的数字滤波器具有更好的抗FWL效应.
基金Acknowledgment We thank Beijing Proteome Research Center, （Beijing, China） for its enthusiastic technological support and for the theory of 2-D DIGE. We also thank（Changsha, China） College of Life Sciences at Hunan Normal University for supporting the MS technology. Finally, we are very grateful to our collaborators for their help, as well as their valuable discussions and suggestions during the course of this work. This work was supported by two grants from the National Natural Science Foundation of China （NO. 30170480 and NO. 30470884）.
文摘An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the? values from the extraction-experimentally obtained logKD,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, KD,Pic, denotes an individual distribution constant of Pic﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the? terms in their functional expressions.
文摘The COVID-19 pandemic has revealed sex-based differences in anti-viral responses,with a higher rate of SARS-CoV-2 infections as well as a higher rate of morbidity and mortality in men than in women.Males and females also show disparate immune responses to COVID-19 infection,which may be important contributors to lower rates of infection,disease severity and deaths in women than in men.Here,the authors review sex differences in SARS-CoV-2 infections,anti-viral immunity and vaccine responses,putting forth the importance of sex,the underappreciated variables in vaccine response and disease infectivity.
文摘Background: Metabolic syndrome (MS) is common among people with type 2 diabetes. The purpose of this study was to assess the proportion of MS and its individual components among type 2 diabetic adults, to stratify these by gender and to determine their association with ischemic heart disease (IHD). Method: A cross-sectional multicentre study was conducted in public and private sector clinics in Karachi, Pakistan. A pretested structured questionnaire and medical records were used to collect information from 889 people with type 2 diabetes after informed consent. Chi-square test and odds ratios with 95% CI were used to assess the association of MS, its components and IHD. Adjusted odds ratios were used to evaluate the differences of MS and its components by gender. Results: In all, 70% of the participants had MS. The likelihood of having IHD among those with MS was higher (OR = 3.21;95%CI = 2.22 - 4.65). Of the individual MS components, obesity conferred the strongest association with IHD (OR = 2.57;95%CI = 1.91 - 3.43). Multivariate analysis showed an increased proportion of MS among women (AOR = 1.63;95%CI = 1.18 - 2.24). Of the individual MS components, women had a higher prevalence of obesity (AOR = 4.70;95%CI = 3.30 - 6.70). Conclusion: A very high burden of MS among type 2 diabetics has been identified in this study. Dedicated interventions are needed to prevent/delay the onset of MS and the associated morbidity and mortality.
文摘In this paper,the forecasting equations of a 2nd-order space-time differential remainder are deduced from the Navier-Stokes primitive equations and Eulerian operator by Taylor-series expansion.Here we introduce a cubic spline numerical model(Spline Model for short),which is with a quasi-Lagrangian time-split integration scheme of fitting cubic spline/bicubic surface to all physical variable fields in the atmospheric equations on spherical discrete latitude-longitude mesh.A new algorithm of"fitting cubic spline—time step integration—fitting cubic spline—……"is developed to determine their first-and2nd-order derivatives and their upstream points for time discrete integral to the governing equations in Spline Model.And the cubic spline function and its mathematical polarities are also discussed to understand the Spline Model’s mathematical foundation of numerical analysis.It is pointed out that the Spline Model has mathematical laws of"convergence"of the cubic spline functions contracting to the original functions as well as its 1st-order and 2nd-order derivatives.The"optimality"of the 2nd-order derivative of the cubic spline functions is optimal approximation to that of the original functions.In addition,a Hermite bicubic patch is equivalent to operate on a grid for a 2nd-order derivative variable field.Besides,the slopes and curvatures of a central difference are identified respectively,with a smoothing coefficient of 1/3,three-point smoothing of that of a cubic spline.Then the slopes and curvatures of a central difference are calculated from the smoothing coefficient 1/3 and three-point smoothing of that of a cubic spline,respectively.Furthermore,a global simulation case of adiabatic,non-frictional and"incompressible"model atmosphere is shown with the quasi-Lagrangian time integration by using a global Spline Model,whose initial condition comes from the NCEP reanalysis data,along with quasi-uniform latitude-longitude grids and the so-called"shallow atmosphere"Navier-Stokes primitive equations in the spherical coordinates.The Spline Model,which adopted the Navier-Stokes primitive equations and quasi-Lagrangian time-split integration scheme,provides an initial ideal case of global atmospheric circulation.In addition,considering the essentially non-linear atmospheric motions,the Spline Model could judge reasonably well simple points of any smoothed variable field according to its fitting spline curvatures that must conform to its physical interpretation.
文摘Boundary procedure is an important phenomenon in numerical simulation. To reduce or eliminate the spurious reflections significantly which is occurred in boundary is a challenging and vital approach. The appropriate artificial numerical boundaries can be applied to eliminate the effect of unnecessary spurious reflections in case of the numerical simulations of wave propagation phenomena problems. Typically, to reduce the artificial reflections, the absorbing boundary conditions are necessary. In this paper, we overview and investigate the appropriate typical absorbing boundary conditions and analyzed the boundary effect of two dimensional wave equation numerically. Reflections over the wide-ranging incident angles are complicated to eliminate, but the absorbing boundary conditions that we have applied are computationally cost efficient, easy to apply and able to reduce reflections significantly. For numerical solution, finite difference method is applied to develop numerical scheme using 2D wave equation. Using the developed numerical scheme, we obtain the numerical solution of the governing equation as an initial boundary value problem and realize the qualitative behavior of the solution in infinite space. The finite difference numerical scheme has been investigated by developing MATLAB programming language code. Numerical results have been discussed and analyzed with presenting different qualitative behavior of the numerical scheme. The accuracy and efficiency of the numerical scheme has been illustrated. The stability analysis was discussed and verified stability condition. Using the numerical scheme and absorbing boundary conditions, the boundary effects and absorption of spurious reflection of boundary have been demonstrated.
