CO_(2) conversion into value-added products by electro-, photoand plasma catalysis under mild operating conditions(ambient temperature and pressure) is an emerging area to achieve carbon circularity by producing chemi...CO_(2) conversion into value-added products by electro-, photoand plasma catalysis under mild operating conditions(ambient temperature and pressure) is an emerging area to achieve carbon circularity by producing chemicals and fuels using directly renewable energy. Among all CO_(2) conversion approaches, the electrocatalytic reduction of CO_(2) is the most mature technology, capable of achieving high productivity(i.e. high current densities) at large scale, especially for producing carbon monoxide(CO), but with many examples showing selectivity to C_(2) carbon products.展开更多
Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- ...Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- mate PD values, the ＂HY-2＂ system includes a calibration microwave radiometer （CMR） operating at 18.7, 23.8 and 37 GHz. The PD data of the CMR were compared and validated by coincident radiosonde profiles from ten globally distributed radiosonde stations during October 2011 to August 2012. The temporal interval was 1 h. In order to avoid land contamination, different spatial intervals between these two data sets were tested. The empirical fit function of PD uncertainty and spatial interval was found and extrapolated to the ideal situation that the data of CMR and radiosonde were totally coincident. The stability of the brightness temperature of the CMR and its impact on the PD correction was also studied. Consequently, the uncertainty of the PD algorithm of the CMR was estimated to be 2.1 cm.展开更多
A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tange...A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tangency and curvature, huge number of line segments, and short lengths of line segments. These disadvantages hinder the development of high speed machining. To smooth the linear tool path and improve machining efficiency of short line segments, this paper presents an optimal feed interpolator based on G^2 continuous Bézier curves for the linear tool path. First, the areas suitable for fitting are screened out based on the geometric characteristics of continuous short segments (CSSs). CSSs in every area are compressed and fitted into a G^2 Continuous Bézier curve by using the least square method. Then a series of cubic Bézier curves are generated. However, the junction between adjacent Bézier curves is only G^0 continuous. By adjusting the control points and inserting Bézier transition curves between adjacent Bézier curves, the G^2 continuous tool path is constructed. The fitting error is estimated by the second-order Taylor formula. Without iteration, the fitting algorithm can be implemented in real-time environment. Second, the optimal feed interpolator considering the comprehensive constraints (such as the chord error constraint, the maximum normal acceleration, servo capacity of each axis, etc.) is proposed. Simulation and experiment are conducted. The results shows that the proposed method can generate smooth path, decrease the amount of segments and reduce machining time for machining of linear tool path. The proposed research provides an effective method for high-speed machining of complex 2-D/3-D profiles described by short line segments.展开更多
Methyl N-phenyl carbamate(MPC), an important organic chemical, can be synthesized from aniline,CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluate...Methyl N-phenyl carbamate(MPC), an important organic chemical, can be synthesized from aniline,CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent,the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mechanism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.展开更多
The main sources of nssSO 2- 4 and NO - 3 were summarized in this paper. By analyzing the spatial distribution features of major ions in Antarctic ice sheet and studying on the different time of the same volca...The main sources of nssSO 2- 4 and NO - 3 were summarized in this paper. By analyzing the spatial distribution features of major ions in Antarctic ice sheet and studying on the different time of the same volcanic event recorded by different ice cores from different regions in Antarctica, this paper intends to study the transmission path of nssSO 2- 4 and NO - 3. Results show that nssSO 2- 4 and NO - 3 are transmitted to the ice sheet through long distance and high altitude. The procedure of the transmission is that nssSO 2- 4 and NO - 3 are transmitted to the level between the top of troposphere and the bottom of stratosphere, then subsided to the ice sheet surface and spread to other regions.展开更多
We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum...We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum is obviously extended and the short quantum path is selected to contribute to the spectrum, because the corresponding long path is seriously suppressed. Then the combined Coulomb and laser field potentials and the time-dependent electron wave packet distributions are applied to illustrate the physical mechanism of high-order harmonic gen- eration. Finally, by adjusting the intensity of the static field and superposing a properly selected range of the HHG spectrum, a 90-as isolated attosecond pulse is straightforwardly obtained.展开更多
Tracy-Widom distribution was rst discovered in the study of largest eigenvalues of high dimensional Gaussian unitary ensembles(GUE),and since then it has appeared in a number of apparently distinct research elds.It is...Tracy-Widom distribution was rst discovered in the study of largest eigenvalues of high dimensional Gaussian unitary ensembles(GUE),and since then it has appeared in a number of apparently distinct research elds.It is believed that Tracy-Widom distribution have a universal feature like classic normal distribution.Airy2 process is de ned through nite dimensional distributions with Tracy-Widom distribution as its marginal distributions.In this introductory survey,we will briey review some basic notions,intuitive background and fundamental properties concerning Tracy-Widom distribution and Airy2 process.For sake of reading,the paper starts with some simple and well-known facts about normal distributions,Gaussian processes and their sample path properties.展开更多
Objective: To observe the effect of total flavonoids of Scutellaria barbata (TF‑SB) on the injury of high glucose induced podocytes (MPC‑5) and the influence of Smad4/PKM2/HIF‑1α pathway. Methods: Firstly, CCK8 was u...Objective: To observe the effect of total flavonoids of Scutellaria barbata (TF‑SB) on the injury of high glucose induced podocytes (MPC‑5) and the influence of Smad4/PKM2/HIF‑1α pathway. Methods: Firstly, CCK8 was used to analyze the safety and efficacy concentration of TF‑SB on MPC‑5 cells. Then, MPC‑5 was then divided into the control group, model group and TF‑SB group. In addition to the control group, model group and TF‑SB group were induced by high glucose to establish MPC‑5 cell injury model. The effects of TF‑SB on ATP, apoptosis and ROS levels of MPC‑5 cells were detected respectively. The contents of IL‑1β, TNF‑α, and MCP‑1 were determined by ELISA, the expression abundance of glycolytic genes (GLU1, PFK1 and HK1) were detected by RT‑PCR. Western blot method was used to detect the expression level of related proteins in Smad4/PKM2/HIF‑1α pathway. Results: Compared with the blank group, ATP content, GLU1, PKF1 and HK1 expression abundance of MPC‑5 cells in the model group decreased significantly, apoptosis, ROS level and IL‑1 β、 TNF‑ α And MCP‑1 significantly increased (P<0.01);Compared with model group, ATP content, GLU1, PKF1 and HK1 expression abundance, apoptosis, ROS level and IL‑1β in TF‑SB group were significantly increased , TNF‑ α The contents of MCP‑1 and MCP‑1 decreased significantly (P<0.01). In addition, compared with the blank group, the model group Smad4 and HIF‑1 α The protein expression and PKM2 expression in nucleus were significantly increased, while PKM2 expression in cytoplasm was significantly decreased (P<0.01);Compared with model group, TF‑SB group Smad4, HIF‑1 α The expression of PKM2 in the nucleus and expression of PKM2 were significantly decreased, while the expression of PKM2 in the cytoplasm was significantly increased (P<0.01). Conclusion: TF‑SB promotes the mitochondrial activity of MPC‑5 cells to induce glycolysis, and then inhibits the secretion of inflammation, which may play a role in treating diabetes nephropathy by inhibiting Smad4/PKM2/HIF‑1α signaling pathway.展开更多
We study the Hamiltonian, path integral and Becchi-Rouet-Stora and Tyutin (BRST) formulations of the restricted gauge theory of QCD2 à la Cho et al. under appropriate gauge-fixing conditions.
文摘CO_(2) conversion into value-added products by electro-, photoand plasma catalysis under mild operating conditions(ambient temperature and pressure) is an emerging area to achieve carbon circularity by producing chemicals and fuels using directly renewable energy. Among all CO_(2) conversion approaches, the electrocatalytic reduction of CO_(2) is the most mature technology, capable of achieving high productivity(i.e. high current densities) at large scale, especially for producing carbon monoxide(CO), but with many examples showing selectivity to C_(2) carbon products.
基金The Marine Public Welfare Project of China under contract No.201105032-1the National High-Tech Project of China under contract No.2013AA09A505
文摘Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- mate PD values, the ＂HY-2＂ system includes a calibration microwave radiometer （CMR） operating at 18.7, 23.8 and 37 GHz. The PD data of the CMR were compared and validated by coincident radiosonde profiles from ten globally distributed radiosonde stations during October 2011 to August 2012. The temporal interval was 1 h. In order to avoid land contamination, different spatial intervals between these two data sets were tested. The empirical fit function of PD uncertainty and spatial interval was found and extrapolated to the ideal situation that the data of CMR and radiosonde were totally coincident. The stability of the brightness temperature of the CMR and its impact on the PD correction was also studied. Consequently, the uncertainty of the PD algorithm of the CMR was estimated to be 2.1 cm.
基金Supported by National Natural Science Foundation of China(Grant No.50875171)National Hi-tech Research and Development Program of China(863 Program,Grant No.2009AA04Z150)
文摘A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tangency and curvature, huge number of line segments, and short lengths of line segments. These disadvantages hinder the development of high speed machining. To smooth the linear tool path and improve machining efficiency of short line segments, this paper presents an optimal feed interpolator based on G^2 continuous Bézier curves for the linear tool path. First, the areas suitable for fitting are screened out based on the geometric characteristics of continuous short segments (CSSs). CSSs in every area are compressed and fitted into a G^2 Continuous Bézier curve by using the least square method. Then a series of cubic Bézier curves are generated. However, the junction between adjacent Bézier curves is only G^0 continuous. By adjusting the control points and inserting Bézier transition curves between adjacent Bézier curves, the G^2 continuous tool path is constructed. The fitting error is estimated by the second-order Taylor formula. Without iteration, the fitting algorithm can be implemented in real-time environment. Second, the optimal feed interpolator considering the comprehensive constraints (such as the chord error constraint, the maximum normal acceleration, servo capacity of each axis, etc.) is proposed. Simulation and experiment are conducted. The results shows that the proposed method can generate smooth path, decrease the amount of segments and reduce machining time for machining of linear tool path. The proposed research provides an effective method for high-speed machining of complex 2-D/3-D profiles described by short line segments.
基金Supported by the National Natural Science Foundation of China(20976035)the Natural Science Foundation of Tianjin City(12JCYBJC12800)the Key Basic Research Project of Applied Basic Research Plan of Hebei Province(12965642D)
文摘Methyl N-phenyl carbamate(MPC), an important organic chemical, can be synthesized from aniline,CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent,the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mechanism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.
文摘The main sources of nssSO 2- 4 and NO - 3 were summarized in this paper. By analyzing the spatial distribution features of major ions in Antarctic ice sheet and studying on the different time of the same volcanic event recorded by different ice cores from different regions in Antarctica, this paper intends to study the transmission path of nssSO 2- 4 and NO - 3. Results show that nssSO 2- 4 and NO - 3 are transmitted to the ice sheet through long distance and high altitude. The procedure of the transmission is that nssSO 2- 4 and NO - 3 are transmitted to the level between the top of troposphere and the bottom of stratosphere, then subsided to the ice sheet surface and spread to other regions.
基金Supported by the National Natural Science Foundation of China under Grant No 11404204the Key Project of the Ministry of Education of China under Grant No 211025+1 种基金the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111404120004the Natural Science Foundation for Young Scientists of Shanxi Province of China under Grant No2009021005
文摘We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum is obviously extended and the short quantum path is selected to contribute to the spectrum, because the corresponding long path is seriously suppressed. Then the combined Coulomb and laser field potentials and the time-dependent electron wave packet distributions are applied to illustrate the physical mechanism of high-order harmonic gen- eration. Finally, by adjusting the intensity of the static field and superposing a properly selected range of the HHG spectrum, a 90-as isolated attosecond pulse is straightforwardly obtained.
基金the National Natural Science Foundation of China(11731012,11871425)Fundamental Research Funds for Central Universities grant(2020XZZX002-03).
文摘Tracy-Widom distribution was rst discovered in the study of largest eigenvalues of high dimensional Gaussian unitary ensembles(GUE),and since then it has appeared in a number of apparently distinct research elds.It is believed that Tracy-Widom distribution have a universal feature like classic normal distribution.Airy2 process is de ned through nite dimensional distributions with Tracy-Widom distribution as its marginal distributions.In this introductory survey,we will briey review some basic notions,intuitive background and fundamental properties concerning Tracy-Widom distribution and Airy2 process.For sake of reading,the paper starts with some simple and well-known facts about normal distributions,Gaussian processes and their sample path properties.
基金Heilongjiang Traditional Chinese Medicine Research Project (No.ZHY19?058)。
文摘Objective: To observe the effect of total flavonoids of Scutellaria barbata (TF‑SB) on the injury of high glucose induced podocytes (MPC‑5) and the influence of Smad4/PKM2/HIF‑1α pathway. Methods: Firstly, CCK8 was used to analyze the safety and efficacy concentration of TF‑SB on MPC‑5 cells. Then, MPC‑5 was then divided into the control group, model group and TF‑SB group. In addition to the control group, model group and TF‑SB group were induced by high glucose to establish MPC‑5 cell injury model. The effects of TF‑SB on ATP, apoptosis and ROS levels of MPC‑5 cells were detected respectively. The contents of IL‑1β, TNF‑α, and MCP‑1 were determined by ELISA, the expression abundance of glycolytic genes (GLU1, PFK1 and HK1) were detected by RT‑PCR. Western blot method was used to detect the expression level of related proteins in Smad4/PKM2/HIF‑1α pathway. Results: Compared with the blank group, ATP content, GLU1, PKF1 and HK1 expression abundance of MPC‑5 cells in the model group decreased significantly, apoptosis, ROS level and IL‑1 β、 TNF‑ α And MCP‑1 significantly increased (P<0.01);Compared with model group, ATP content, GLU1, PKF1 and HK1 expression abundance, apoptosis, ROS level and IL‑1β in TF‑SB group were significantly increased , TNF‑ α The contents of MCP‑1 and MCP‑1 decreased significantly (P<0.01). In addition, compared with the blank group, the model group Smad4 and HIF‑1 α The protein expression and PKM2 expression in nucleus were significantly increased, while PKM2 expression in cytoplasm was significantly decreased (P<0.01);Compared with model group, TF‑SB group Smad4, HIF‑1 α The expression of PKM2 in the nucleus and expression of PKM2 were significantly decreased, while the expression of PKM2 in the cytoplasm was significantly increased (P<0.01). Conclusion: TF‑SB promotes the mitochondrial activity of MPC‑5 cells to induce glycolysis, and then inhibits the secretion of inflammation, which may play a role in treating diabetes nephropathy by inhibiting Smad4/PKM2/HIF‑1α signaling pathway.
文摘We study the Hamiltonian, path integral and Becchi-Rouet-Stora and Tyutin (BRST) formulations of the restricted gauge theory of QCD2 à la Cho et al. under appropriate gauge-fixing conditions.
