Aim Salvia miltiorrhiza Bunge （SM） and lignum dalbergiae odoriferae （DO） are both traditional Chi- nese medicine that have cardioprotective effects. Here, we further examined the combined effects of SM and DO on r...Aim Salvia miltiorrhiza Bunge （SM） and lignum dalbergiae odoriferae （DO） are both traditional Chi- nese medicine that have cardioprotective effects. Here, we further examined the combined effects of SM and DO on rat myocardial ischemia/reperfusion injury. The possible mechanism of SM and DO also were elucidated. Methods DO was divided into aqueous extract of lignum dalbergiae odoriferae （DOW） and lignum dalbergiae odoriferae oil （DOO）. Sprague-Dawley rats were randomized to seven groups： sham group, model group, treatment groups inclu- ding SM （10 g · kg^-1）, DOW （5 g · kg^-1）, DOO （0.5 ml · kg^-1）, SM ＋ DOW （10 g · kg^-1 ＋ 5 g · kg^-1）, SM ＋ DOO （ 10 g · kg^-1 ＋ 0. 5 ml · kg^-1）. Rats were pretreated with homologous drug for 7 days and then subjec- ted to 30 rain of ischemia followed by 180 rain of reperfusion. Electrocardiogram （ECG） and heart rate were moni- tored and recorded continuously. At the end of reperfusion, blood samples were collected to determine the serum levels of creatine kinase-MB （CK-MB） and lactate dehydrogenase （LDH）. Hearts were harvested to assess heart- body rate, infarct size and histopathological changes as well. Maximum and minimum effective points were deter- mined by measuring indicators associate with myocardial injury at different time-points of reperfusion （Smin, 15min, 30min, 45rain, 60min, 120min, 180min）. The potential therapeutic mechanism of SM and SM ＋ DOO were carried out by detecting superoxide dismutase （SOD）, malondialdehyde （MDA）, tumor necrosis factor-alpha （TNF-alpha） and interleukin 6 （IL-6）. Results The results showed SM and DO can ameliorate cardiac function respectively, and this cardioprotective effect was further strengthened by their combinations. Among all the combi- nations, SM ＋ DOO showed predominant potential to improve ECG and heart rate, reduce heart-body rate （28.5% ＋ 1.4% , P 〈 0.01 vs model） and myocardial infarct size （ 20.96% ＋ 1.61% , P 〈 0.01 vs model, P 〈 0.05 vs SM） , attenuate histopathological damage, decrease the levels of CK-MB and LDH （P 〈 0.01 vs model, P 〈 0.05 vs SM）. The maximum effective points of SM and SM ＋ DOO were 15min and 30rain respectively, and the minimum effective points of them were 180rain. In reducing serum level of MDA, TNF-alpha, IL-6 and increasing SOD activ- ity, SM ＋ DOO was similar to SM. Conclusion The results of this study indicated that SM ＋ DOO have combined effects that are highly effective than single pretreatment against myocardial ischemie reperfusion injury in rats. The possible mechanism of SM and DO were likely through its anti-oxidant and anti-inflammatory properties, and thus may be an effective and promising medicine for both prophylaxis and treatment of ischemic heart disease.展开更多
The seedlings of Vernicia montana derived from seeds soaking with water (the first group)or 300 mg5L -1 mixed nitric_acid rare earth solution (the second group) were treated with various concentrations of mixed nitric...The seedlings of Vernicia montana derived from seeds soaking with water (the first group)or 300 mg5L -1 mixed nitric_acid rare earth solution (the second group) were treated with various concentrations of mixed nitric_acid rare earth solution by foliage spraying. The results showed that the seedling heights sprayed with 100 和 1 000 mg·L -1 of the first group and with 50 和 100 mg·L -1 of the second group were significantly higher than the controls, and the diameter at ground level sprayed with 300 mg·L -1 of the second group was significantly greater than the control, being 26.92% more than the latter; except for spraying with 0 mg5L -1 and 700～1 500 mg5L -1 of the second group, the seedling dry weight above ground of others was 29.13%～73.91% greater than the control, whereas the seedling dry weight under ground of others was 20.78%～116.88% greater than the control; the contents of chlorophyll a and chlorophyll b for all spraying seedling were 91.67%～191.67% and 87.5%～306.25% greater than the control, respectively, and soluble proteins and soluble sugars were 16.00%～179.78% and 10.73%～105.65% greater than the control, respectively. Compared with the control, the activity of SOD tended to increase, whereas the contents of MDA decreased. These indicated that spraying leaves with optimum concentration of mixed nitric_acid rare earth solution could markedly promote the growth of seedlings and improve resistance ability of V. montana seedlings to bad environment. On the whole, the effects of spraying the leaves of seedling with 50～500 mg5L -1 mixed nitric_acid rare earth solution, which were derived from seeds soaking with 300 mg·L -1 mixed nitric_acid rare earth solution, were good.展开更多
A new binuclear copper(Ⅱ) complex, [Cu2(phen)2(H2O)2( μ2-C2O4)](NO3)2, has been synthesized and characterized by elemental analysis, IR and UV-Vis spectrum. Its crystal structure was determined by single crystal X-r...A new binuclear copper(Ⅱ) complex, [Cu2(phen)2(H2O)2( μ2-C2O4)](NO3)2, has been synthesized and characterized by elemental analysis, IR and UV-Vis spectrum. Its crystal structure was determined by single crystal X-ray diffraction techniques. Crystal data: monoclinic, space group P21/c, a=0.712 21(8) nm, b=1.170 93(14) nm, c=1.783 7(2) nm, β=111.828(2)°, and V=1.380 8(3) nm3, Dc=1.769 Mg·m-3, Z=2, F(000)=744, R1=0.025 4, wR2=0.069 5, Gof=1.077, Δρ=328^-455 e·nm-3. The complex is packed by one centrosymmetry binuclear copper(Ⅱ) unit, oxalate dianion and NO3- anion. In the molecule structure of the title complex, two Cu(Ⅱ) ions are bridged by oxalate dianion and each Cu(Ⅱ) ions coordinates with two nitrogen atoms from 1,10-phenanthroline ligand and one oxygen atom from water to form a five-coordinate distorted square-pyramidal configuration. The hydrogen bonds are observed between coordinated water molecules and NO3- anions. The analysis of the crystal structure indicates that the complex has a two-dimensional stacking network structure, which is formed by intramolecular hydrogen bonds, intermolecular hydrogen bonds and stacking effect of aromatic ring. CCDC: 255345.展开更多
The geometric configurations of binuclear Zinc( complex Zn2[(n-Bu)2NCSS]4 and the ligand Na[(n-Bu)2 NCSS] have been optimized by B3LYP quantum chemical method. The electronic structures have been performed by density ...The geometric configurations of binuclear Zinc( complex Zn2[(n-Bu)2NCSS]4 and the ligand Na[(n-Bu)2 NCSS] have been optimized by B3LYP quantum chemical method. The electronic structures have been performed by density functional theory at B3LYP/6-31G* level. The electronic spectrums of the complex and ligand were calculated by ZINDO/S-CIS method. It is indicated from the calculation that: (1) The coordination effect of bridging ligand is bigger than that of chelating one, and the bridging ligands also translate more charge to Zn than the chelating one. (2) The calculated results about electronic spectrums are similarly to experimental measurement, and farther explain that absorption band at λ=267 nm of complex is assigned to two n → π* transitions :one arising from the bridging ligands and the another mainly arising from the chelating ligands;but absorption band at λ=236 nm of complex is assigned to π → π* transition which the electron mainly translates from the bridging ligands to the chelating ligands. (3) By consideration of delocalization and polar effects in coordination, the charge transfer from ligand to metal decreases the π-π and p-π conjugation effects in the chromophore group NCS2 and to increase the energy needed for the π → π* and n → π* transitions, and results in the absorption bands shifting towards the short wavelength direction.展开更多
During the propagation of high-power lasers within internal channels,the laser beam heats the propagation medium,causing the thermal blooming effect that degrades the beam quality at the output.The intricate configura...During the propagation of high-power lasers within internal channels,the laser beam heats the propagation medium,causing the thermal blooming effect that degrades the beam quality at the output.The intricate configuration of the optical path within the internal channel necessitates complex and time-consuming efforts to assess the impact of thermal blooming effect on the optical path.To meet the engineering need for rapid evaluation of thermal blooming effect in optical paths,this study proposed a rapid simulation method for the thermal blooming effect in internal optical paths based on the finite element method.This method discretized the fluid region into infinitesimal elements and employed finite element method for flow field analysis.A simplified analytical model of the flow field region in complex internal channels was established,and regions with similar thermal blooming effect were divided within this model.Based on the calculated optical path differences within these regions,numerical simulations of phase distortion caused by thermal blooming were conducted.The calculated result were compared with those obtained using the existing methods.The findings reveal that for complex optical paths,the discrepancy between the two approaches is less than 3.6%,with similar phase distortion patterns observed.For L-type units,this method and the existing methods identify the same primary factors influencing aberrations and exhibit consistent trends in their variation.This method was used to analyze the impact of thermal blooming effect in a straight channel under different gravity directions.The results show that phase distortion varies with changes in the direction of gravity,and the magnitude of the phase difference is strongly correlated with the component of gravity perpendicular to the optical axis.Compared to the existing methods,this approach offers greater flexibility,obviates the need for complex custom analysis programming.The analytical results of this method enable a rapid assessment of the thermal blooming effect in optical paths within the internal channel.This is especially useful during the engineering design.These results also provide crucial references for developing strategies to suppress thermal blooming effect.展开更多
Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads ...Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.展开更多
Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.Thi...Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions,employing both numerical simulations and field tests.It focuses on the effects of top and side blasting,with particular emphasis on fracture modes,damage patterns,and fragment sizes,as well as the causes of different failure modes and the propagation of stress waves.The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts.The results show that side-blasting leads to complete fragmentation,with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface,concentrating damage near the surface.During top-blasting,the upper half of the frustum undergoes fragmentation,while the lower half experiences cracking.Tensile waves propagate from the top to the bottom surface,forming larger blocks in regions with lower wave intensity.Three distinct damage zones within the frustum were identified,and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass.As the charge mass increased from 1.0 kg to 4.0 kg,the maximum fragment size decreased.Detonation at the center of the frustum's side resulted in the most severe fragmentation,with a 51.8%reduction in fragment size compared to other detonation positions.Finally,four broken modes were classified,each influenced by charge mass and explosive location.This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.展开更多
Experimental and theoretical researches on the doping effect of interface binding state with homologous and heterogeneous dopants(d) in the system of PCD etc,as well as the action of intermediate layers between D /d a...Experimental and theoretical researches on the doping effect of interface binding state with homologous and heterogeneous dopants(d) in the system of PCD etc,as well as the action of intermediate layers between D /d at superhigh pressure and high temperature(HP-HT) are reported in this paper.展开更多
Aim Reduction of Sheng-Nao-Kang decoction （RSNK）, is a modified traditional Chinese medicinal formula of Sheng-Nao-Kang pill preparation, which is protective in rats against focal cerebral ischemia/reperfusion （I/R...Aim Reduction of Sheng-Nao-Kang decoction （RSNK）, is a modified traditional Chinese medicinal formula of Sheng-Nao-Kang pill preparation, which is protective in rats against focal cerebral ischemia/reperfusion （I/R） injury. In the current study, we investigate the protective effect of RSNK against apoptosis and oxidative damage induced by cerebral I/R and explore the underlying mechanisms. Cerebral I/R injury was induced by in- traluminal middle cerebral artery occlusion （MCAO） for 2 h followed by reperfusion for 24 h in adult male Sprague- Dawley rats. Rats were randomized into seven groups （n- 8）： Sham group, I/R group, RSNK-treated groups （ 0.7 g · kg ^- 1, 1 . 4 g · kg ^- 1 and 2. 8 g · kg^ - 1 ） , nimodipine （NMP） -treated group and Whitmania pigra Whitman （WW）-treated group. Neurological deficit scores, cerebral humidity content and cerebral infarction volume were measured after the 24 h reperfusion. Malondialdehyde （ MDA）, superoxide dismutase （ SOD）, catalase （ CAT）, inducible nitric oxide synthase （iNOS） and total nitric oxide synthase （TNOS） in serum were measured by assay kits for biochemical analysis. Histological structures of the cortex of the ipsilateral ischemic cerebral hemisphere in rats were observed by Nissl staining. The caspase-3 protein content in the hippocampus and cortex was detected by immunohistochemistry. Additionally, Bax and Bcl-2 protein expressions in the injured brain were evaluated by Western blot. RSNK administration not only markedly improved neurological deficit scores, but also reduced cere- bral humidity content and cerebral infarction volume, lowered MDA content, up-regulated SOD and CAT levels, down-regulated iNOS and TNOS levels, restrained the expression of caspase-3 positive protein and alleviated the Bax and Bcl-2 protein expressions.展开更多
Projectile size effect is of great importance since the scaling researches are extensively applied to concrete penetration investigations. This paper numerically deals with the projectile size effect on penetration re...Projectile size effect is of great importance since the scaling researches are extensively applied to concrete penetration investigations. This paper numerically deals with the projectile size effect on penetration resistance via the recently developed Lattice Discrete Particles Model(LDPM) which is featured with mesoscale constitutive laws governing the interaction between adjacent particles to account for cohesive fracture, strain hardening in compression and compaction due to pore collapse. Simulations of two different penetration tests are carried to shed some light on the size effect issue. The penetration numerical model is validated by matching the projectile deceleration curve of and predicting the depth of penetration(DOP). By constant velocity penetration simulations, the target resistance is found to be dependent on the projectile size. By best fitting numerical results of constant velocity penetration, a size effect law for target resistance is proposed and validated against literature data. Moreover, the size effect is numerically obtained in the projectile with longer extended nose part meanwhile the shorter extended nose is found to improve the DOP since the projectile nose is sharpened.展开更多
The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts c...The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts contained Pd species in mixed valence states,with high valence Pd at the metal‑support interface and zero valence Pd at the metal surface.While the strong coordination of triphenylphosphine(PPh3)to Pd0 on the Pd surface prevents the adsorption of halogenated nitroaromatics and thus dehalogenation,the coordination of sodium metavanadate(NaVO3)to high‑valence Pd sites at the interface helps to activate H2 in a heterolytic pathway for the selective hydrogenation of nitro‑groups.The excellent catalytic performance of the interfacial active sites enables the selective hydrogenation of a wide range of halogenated nitroaromatics.展开更多
文摘Aim Salvia miltiorrhiza Bunge （SM） and lignum dalbergiae odoriferae （DO） are both traditional Chi- nese medicine that have cardioprotective effects. Here, we further examined the combined effects of SM and DO on rat myocardial ischemia/reperfusion injury. The possible mechanism of SM and DO also were elucidated. Methods DO was divided into aqueous extract of lignum dalbergiae odoriferae （DOW） and lignum dalbergiae odoriferae oil （DOO）. Sprague-Dawley rats were randomized to seven groups： sham group, model group, treatment groups inclu- ding SM （10 g · kg^-1）, DOW （5 g · kg^-1）, DOO （0.5 ml · kg^-1）, SM ＋ DOW （10 g · kg^-1 ＋ 5 g · kg^-1）, SM ＋ DOO （ 10 g · kg^-1 ＋ 0. 5 ml · kg^-1）. Rats were pretreated with homologous drug for 7 days and then subjec- ted to 30 rain of ischemia followed by 180 rain of reperfusion. Electrocardiogram （ECG） and heart rate were moni- tored and recorded continuously. At the end of reperfusion, blood samples were collected to determine the serum levels of creatine kinase-MB （CK-MB） and lactate dehydrogenase （LDH）. Hearts were harvested to assess heart- body rate, infarct size and histopathological changes as well. Maximum and minimum effective points were deter- mined by measuring indicators associate with myocardial injury at different time-points of reperfusion （Smin, 15min, 30min, 45rain, 60min, 120min, 180min）. The potential therapeutic mechanism of SM and SM ＋ DOO were carried out by detecting superoxide dismutase （SOD）, malondialdehyde （MDA）, tumor necrosis factor-alpha （TNF-alpha） and interleukin 6 （IL-6）. Results The results showed SM and DO can ameliorate cardiac function respectively, and this cardioprotective effect was further strengthened by their combinations. Among all the combi- nations, SM ＋ DOO showed predominant potential to improve ECG and heart rate, reduce heart-body rate （28.5% ＋ 1.4% , P 〈 0.01 vs model） and myocardial infarct size （ 20.96% ＋ 1.61% , P 〈 0.01 vs model, P 〈 0.05 vs SM） , attenuate histopathological damage, decrease the levels of CK-MB and LDH （P 〈 0.01 vs model, P 〈 0.05 vs SM）. The maximum effective points of SM and SM ＋ DOO were 15min and 30rain respectively, and the minimum effective points of them were 180rain. In reducing serum level of MDA, TNF-alpha, IL-6 and increasing SOD activ- ity, SM ＋ DOO was similar to SM. Conclusion The results of this study indicated that SM ＋ DOO have combined effects that are highly effective than single pretreatment against myocardial ischemie reperfusion injury in rats. The possible mechanism of SM and DO were likely through its anti-oxidant and anti-inflammatory properties, and thus may be an effective and promising medicine for both prophylaxis and treatment of ischemic heart disease.
文摘The seedlings of Vernicia montana derived from seeds soaking with water (the first group)or 300 mg5L -1 mixed nitric_acid rare earth solution (the second group) were treated with various concentrations of mixed nitric_acid rare earth solution by foliage spraying. The results showed that the seedling heights sprayed with 100 和 1 000 mg·L -1 of the first group and with 50 和 100 mg·L -1 of the second group were significantly higher than the controls, and the diameter at ground level sprayed with 300 mg·L -1 of the second group was significantly greater than the control, being 26.92% more than the latter; except for spraying with 0 mg5L -1 and 700～1 500 mg5L -1 of the second group, the seedling dry weight above ground of others was 29.13%～73.91% greater than the control, whereas the seedling dry weight under ground of others was 20.78%～116.88% greater than the control; the contents of chlorophyll a and chlorophyll b for all spraying seedling were 91.67%～191.67% and 87.5%～306.25% greater than the control, respectively, and soluble proteins and soluble sugars were 16.00%～179.78% and 10.73%～105.65% greater than the control, respectively. Compared with the control, the activity of SOD tended to increase, whereas the contents of MDA decreased. These indicated that spraying leaves with optimum concentration of mixed nitric_acid rare earth solution could markedly promote the growth of seedlings and improve resistance ability of V. montana seedlings to bad environment. On the whole, the effects of spraying the leaves of seedling with 50～500 mg5L -1 mixed nitric_acid rare earth solution, which were derived from seeds soaking with 300 mg·L -1 mixed nitric_acid rare earth solution, were good.
文摘A new binuclear copper(Ⅱ) complex, [Cu2(phen)2(H2O)2( μ2-C2O4)](NO3)2, has been synthesized and characterized by elemental analysis, IR and UV-Vis spectrum. Its crystal structure was determined by single crystal X-ray diffraction techniques. Crystal data: monoclinic, space group P21/c, a=0.712 21(8) nm, b=1.170 93(14) nm, c=1.783 7(2) nm, β=111.828(2)°, and V=1.380 8(3) nm3, Dc=1.769 Mg·m-3, Z=2, F(000)=744, R1=0.025 4, wR2=0.069 5, Gof=1.077, Δρ=328^-455 e·nm-3. The complex is packed by one centrosymmetry binuclear copper(Ⅱ) unit, oxalate dianion and NO3- anion. In the molecule structure of the title complex, two Cu(Ⅱ) ions are bridged by oxalate dianion and each Cu(Ⅱ) ions coordinates with two nitrogen atoms from 1,10-phenanthroline ligand and one oxygen atom from water to form a five-coordinate distorted square-pyramidal configuration. The hydrogen bonds are observed between coordinated water molecules and NO3- anions. The analysis of the crystal structure indicates that the complex has a two-dimensional stacking network structure, which is formed by intramolecular hydrogen bonds, intermolecular hydrogen bonds and stacking effect of aromatic ring. CCDC: 255345.
文摘The geometric configurations of binuclear Zinc( complex Zn2[(n-Bu)2NCSS]4 and the ligand Na[(n-Bu)2 NCSS] have been optimized by B3LYP quantum chemical method. The electronic structures have been performed by density functional theory at B3LYP/6-31G* level. The electronic spectrums of the complex and ligand were calculated by ZINDO/S-CIS method. It is indicated from the calculation that: (1) The coordination effect of bridging ligand is bigger than that of chelating one, and the bridging ligands also translate more charge to Zn than the chelating one. (2) The calculated results about electronic spectrums are similarly to experimental measurement, and farther explain that absorption band at λ=267 nm of complex is assigned to two n → π* transitions :one arising from the bridging ligands and the another mainly arising from the chelating ligands;but absorption band at λ=236 nm of complex is assigned to π → π* transition which the electron mainly translates from the bridging ligands to the chelating ligands. (3) By consideration of delocalization and polar effects in coordination, the charge transfer from ligand to metal decreases the π-π and p-π conjugation effects in the chromophore group NCS2 and to increase the energy needed for the π → π* and n → π* transitions, and results in the absorption bands shifting towards the short wavelength direction.
文摘During the propagation of high-power lasers within internal channels,the laser beam heats the propagation medium,causing the thermal blooming effect that degrades the beam quality at the output.The intricate configuration of the optical path within the internal channel necessitates complex and time-consuming efforts to assess the impact of thermal blooming effect on the optical path.To meet the engineering need for rapid evaluation of thermal blooming effect in optical paths,this study proposed a rapid simulation method for the thermal blooming effect in internal optical paths based on the finite element method.This method discretized the fluid region into infinitesimal elements and employed finite element method for flow field analysis.A simplified analytical model of the flow field region in complex internal channels was established,and regions with similar thermal blooming effect were divided within this model.Based on the calculated optical path differences within these regions,numerical simulations of phase distortion caused by thermal blooming were conducted.The calculated result were compared with those obtained using the existing methods.The findings reveal that for complex optical paths,the discrepancy between the two approaches is less than 3.6%,with similar phase distortion patterns observed.For L-type units,this method and the existing methods identify the same primary factors influencing aberrations and exhibit consistent trends in their variation.This method was used to analyze the impact of thermal blooming effect in a straight channel under different gravity directions.The results show that phase distortion varies with changes in the direction of gravity,and the magnitude of the phase difference is strongly correlated with the component of gravity perpendicular to the optical axis.Compared to the existing methods,this approach offers greater flexibility,obviates the need for complex custom analysis programming.The analytical results of this method enable a rapid assessment of the thermal blooming effect in optical paths within the internal channel.This is especially useful during the engineering design.These results also provide crucial references for developing strategies to suppress thermal blooming effect.
基金financially supported by National Natural Science Foundation of China(Grant Nos.52378401,52278504)the Fundamental Research Funds for the Central Universities(Grant No.30922010918)。
文摘Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.
基金the support provided by the Technology Innovation Project (Grant No. KYGYZB002201) for the research work
文摘Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions,employing both numerical simulations and field tests.It focuses on the effects of top and side blasting,with particular emphasis on fracture modes,damage patterns,and fragment sizes,as well as the causes of different failure modes and the propagation of stress waves.The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts.The results show that side-blasting leads to complete fragmentation,with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface,concentrating damage near the surface.During top-blasting,the upper half of the frustum undergoes fragmentation,while the lower half experiences cracking.Tensile waves propagate from the top to the bottom surface,forming larger blocks in regions with lower wave intensity.Three distinct damage zones within the frustum were identified,and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass.As the charge mass increased from 1.0 kg to 4.0 kg,the maximum fragment size decreased.Detonation at the center of the frustum's side resulted in the most severe fragmentation,with a 51.8%reduction in fragment size compared to other detonation positions.Finally,four broken modes were classified,each influenced by charge mass and explosive location.This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.
文摘Experimental and theoretical researches on the doping effect of interface binding state with homologous and heterogeneous dopants(d) in the system of PCD etc,as well as the action of intermediate layers between D /d at superhigh pressure and high temperature(HP-HT) are reported in this paper.
文摘Aim Reduction of Sheng-Nao-Kang decoction （RSNK）, is a modified traditional Chinese medicinal formula of Sheng-Nao-Kang pill preparation, which is protective in rats against focal cerebral ischemia/reperfusion （I/R） injury. In the current study, we investigate the protective effect of RSNK against apoptosis and oxidative damage induced by cerebral I/R and explore the underlying mechanisms. Cerebral I/R injury was induced by in- traluminal middle cerebral artery occlusion （MCAO） for 2 h followed by reperfusion for 24 h in adult male Sprague- Dawley rats. Rats were randomized into seven groups （n- 8）： Sham group, I/R group, RSNK-treated groups （ 0.7 g · kg ^- 1, 1 . 4 g · kg ^- 1 and 2. 8 g · kg^ - 1 ） , nimodipine （NMP） -treated group and Whitmania pigra Whitman （WW）-treated group. Neurological deficit scores, cerebral humidity content and cerebral infarction volume were measured after the 24 h reperfusion. Malondialdehyde （ MDA）, superoxide dismutase （ SOD）, catalase （ CAT）, inducible nitric oxide synthase （iNOS） and total nitric oxide synthase （TNOS） in serum were measured by assay kits for biochemical analysis. Histological structures of the cortex of the ipsilateral ischemic cerebral hemisphere in rats were observed by Nissl staining. The caspase-3 protein content in the hippocampus and cortex was detected by immunohistochemistry. Additionally, Bax and Bcl-2 protein expressions in the injured brain were evaluated by Western blot. RSNK administration not only markedly improved neurological deficit scores, but also reduced cere- bral humidity content and cerebral infarction volume, lowered MDA content, up-regulated SOD and CAT levels, down-regulated iNOS and TNOS levels, restrained the expression of caspase-3 positive protein and alleviated the Bax and Bcl-2 protein expressions.
基金supported by the Natural Science Foundation of Jiangsu Province (No. BK20170824)the Fundamental Research Funds for the Central Universities (No. 30917011343)
文摘Projectile size effect is of great importance since the scaling researches are extensively applied to concrete penetration investigations. This paper numerically deals with the projectile size effect on penetration resistance via the recently developed Lattice Discrete Particles Model(LDPM) which is featured with mesoscale constitutive laws governing the interaction between adjacent particles to account for cohesive fracture, strain hardening in compression and compaction due to pore collapse. Simulations of two different penetration tests are carried to shed some light on the size effect issue. The penetration numerical model is validated by matching the projectile deceleration curve of and predicting the depth of penetration(DOP). By constant velocity penetration simulations, the target resistance is found to be dependent on the projectile size. By best fitting numerical results of constant velocity penetration, a size effect law for target resistance is proposed and validated against literature data. Moreover, the size effect is numerically obtained in the projectile with longer extended nose part meanwhile the shorter extended nose is found to improve the DOP since the projectile nose is sharpened.
文摘The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts contained Pd species in mixed valence states,with high valence Pd at the metal‑support interface and zero valence Pd at the metal surface.While the strong coordination of triphenylphosphine(PPh3)to Pd0 on the Pd surface prevents the adsorption of halogenated nitroaromatics and thus dehalogenation,the coordination of sodium metavanadate(NaVO3)to high‑valence Pd sites at the interface helps to activate H2 in a heterolytic pathway for the selective hydrogenation of nitro‑groups.The excellent catalytic performance of the interfacial active sites enables the selective hydrogenation of a wide range of halogenated nitroaromatics.
