Considering the importance of the road transportation nowadays, concerns related to pavement deterioration and maintenance have become relevant subjects. Especially for commercial vehicles, the vertical dynamic load ...Considering the importance of the road transportation nowadays, concerns related to pavement deterioration and maintenance have become relevant subjects. Especially for commercial vehicles, the vertical dynamic load (characterized by the tire-road interaction) is directly related to wear on the road surface. Given this, the main objective of this paper is to analyse effects of vertical loads applied on the flexible pavement, considering the variation of the condition of shock absorbers from a truck's front suspension. The mea- surements were performed on a rigid truck, with 2 steering front axles, in a durability test track located in Brazil. With a constant load of 6 tons on the front suspension (the maximum allowed load on front axles according to Brazilian legislation), 3 different shock absorber conditions were evaluated: new, used and failed. By applying the relative damage concept, it is possible to conclude that the variation of the shock absorber conditions will significantly affect the vertical load applied on the pavement. Although the results clearly point to a dependent relationship between the load and the condition of the shock ab- sorbers, it is recommended to repeat the same methodology, in future to analyse the influence of other quarter car model variants (such as spring rate, mass and tire spring stiffness).展开更多
The main objective of this paper is to analyse the vertical loads effects applied on the pavement, considering the variation of tire pressure, from a truck's front suspension. For the measurements, a durability test ...The main objective of this paper is to analyse the vertical loads effects applied on the pavement, considering the variation of tire pressure, from a truck's front suspension. For the measurements, a durability test track located in Brazil has been used. The tire pressure was increased by l0 psi from 90 psi to 130 psi with a constant load of 6 t on the front suspension, the maximum allowed load for front axle according to Brazilian legislation. By applying relative damage concept, it is possible to conclude that the variation on the tire pressure will not affect significantly the load applied on the pavement. However, it is recommended to repeat the same methodology in order to analyse the influence on the variation of the other quarter car model variants.展开更多
AIM: To investigate electroacupunture(EA) at the acupoints of Stomach Meridian of Foot-Yangming(SMFY), Gallbladder Meridian of Foot-Yangming(SMFY) on gastric mucosal intestinal trefoil factor (ITF) gene expre...AIM: To investigate electroacupunture(EA) at the acupoints of Stomach Meridian of Foot-Yangming(SMFY), Gallbladder Meridian of Foot-Yangming(SMFY) on gastric mucosal intestinal trefoil factor (ITF) gene expression detection in stress-induced rats with gastric mucosal lesion, and to explore the regulatory mechanism and significance of EA-related gastric mucosal protective effect. METHODS: Forty rats were randomly divided into 4 groups: Blank group, Model group, Model group+EA at acupoints of SMFY group("SMFY group"), and Model group+EA at acupoints of GMFY group(GMFY group). All rats (except blank group) were made model by water immersion and restraint stress (WRS). Then the gastric mucosa tissue in each rat was taken off alter assessment of gastric mucosal lesion index(GUI), and the expression of ITF mRNA of the tissues was detected by reverse transcdption-polymerase chain reaction(RT-PCR) method. RESULTS: Compared with Model group(S4.3± 1.34), the GUI value in SMFY group (31±2.211 decreased significantly(P〈0.01), so did that in GMFY group (39.8± 1.62, P〈0.05), meanwhile GUI value in SMFY group was significantly lower than in GMFY group(P〈0.01). Compared with Model group (0.65±0.01), EA had a tendency to improve the expression of gastric mucosal ITFmRNA gene: such tendency existed in GMFY group (0.66±0.01) but with no signficant difference(P〉 0.05), in SMFY group(0.76±0.01) with an extremely obvious difference (P〈0.01), furthermore the expression in SMFY group was significantly higher than in GMFY group (P〈 0.01).CONCLUSION: The gastric mucosal protective effect by EA at the acupoints of SMFY and GMFY was related to the expression variance of ITF, indicating certain meridian specificity exists, It could be one proof for the TCM theory "Relative pardcularity between SMFY and stomach".展开更多
The deformation work rate can be expressed by the time rate of pair functional potentials which describe the energy of materi- als in terms of atomic bonds and atom embedding interactions. According to Cauchy-Born rul...The deformation work rate can be expressed by the time rate of pair functional potentials which describe the energy of materi- als in terms of atomic bonds and atom embedding interactions. According to Cauchy-Born rule, the relations between the micro- scopic deformations of atomic bonds and electron gas and macroscopic deformation are established. Further, atomic bonds are grouped according to their directions, and atomic bonds in the same direction are simplified as a spring-bundle component. Atom embedding interactions in unit reference volume are simplified as a cubage component. Consequently, a material model com- posed of spring-bundle components and a cubage component is established. Since the essence of damage is the decrease and loss of atomic bonding forces, the damage effect can be reflected by the response functions of these two kinds of components. For- mulating the mechanical responses of two kinds of components, the corresponding elasto-damage constitutive equations are de- rived. Considering that slip is the main plastic deformation mechanism of polycrystalline metals, the slip systems of crystal are extended to polycrystalline, and the slip components are proposed to describe the plastic deformation. Based on the decomposition of deformation gradient and combining the plastic response with the elasto-damage one, the elasto-plastic damage constitutive equations are derived. As a result, a material model iormulated with spring-bundle components, a cubage component and slip components is established. Different from phenomenological constitutive theories, the mechanical property of materials depends on the property of components rather than that directly obtained on the representative volume element. The effect of finite deformation is taken into account in this model. Parameter calibration procedure and the basic characteristics of this model are discussed.展开更多
The toxic effects of tributyltin(TBT) have been extensively documented in several types of cells, but the molecular mechanisms related to the genotoxic effects of TBT have still not been fully elucidated. Our study ...The toxic effects of tributyltin(TBT) have been extensively documented in several types of cells, but the molecular mechanisms related to the genotoxic effects of TBT have still not been fully elucidated. Our study showed that exposure of human hepatoma G2 cells to 1–4 μmol/L TBT for 3 hr caused severe DNA damage in a concentration-dependent manner. Moreover, the expression levels of key DNA damage sensor genes such as the replication factor C, proliferating cell nuclear antigen and poly(ADP-ribose)polymerase-1 were inhabited in a concentration-dependent manner. We further demonstrated that TBT induced cell apoptosis via the p53-mediated pathway, which was most likely activated by the ataxia telangiectasia mutated and rad-3 related(ATR)protein kinase. The results also showed that cytochrome c, caspase-3, caspase-8,caspase-9, and the B-cell lymphoma 2 were involved in this process. Taken together, we demonstrated for the first time that the inhibition of the DNA repair system might be more responsible for TBT-induced genotoxic effects in cells. Then the generated DNA damage induced by TBT initiated ATR-p53-mediated apoptosis.展开更多
文摘Considering the importance of the road transportation nowadays, concerns related to pavement deterioration and maintenance have become relevant subjects. Especially for commercial vehicles, the vertical dynamic load (characterized by the tire-road interaction) is directly related to wear on the road surface. Given this, the main objective of this paper is to analyse effects of vertical loads applied on the flexible pavement, considering the variation of the condition of shock absorbers from a truck's front suspension. The mea- surements were performed on a rigid truck, with 2 steering front axles, in a durability test track located in Brazil. With a constant load of 6 tons on the front suspension (the maximum allowed load on front axles according to Brazilian legislation), 3 different shock absorber conditions were evaluated: new, used and failed. By applying the relative damage concept, it is possible to conclude that the variation of the shock absorber conditions will significantly affect the vertical load applied on the pavement. Although the results clearly point to a dependent relationship between the load and the condition of the shock ab- sorbers, it is recommended to repeat the same methodology, in future to analyse the influence of other quarter car model variants (such as spring rate, mass and tire spring stiffness).
文摘The main objective of this paper is to analyse the vertical loads effects applied on the pavement, considering the variation of tire pressure, from a truck's front suspension. For the measurements, a durability test track located in Brazil has been used. The tire pressure was increased by l0 psi from 90 psi to 130 psi with a constant load of 6 t on the front suspension, the maximum allowed load for front axle according to Brazilian legislation. By applying relative damage concept, it is possible to conclude that the variation on the tire pressure will not affect significantly the load applied on the pavement. However, it is recommended to repeat the same methodology in order to analyse the influence on the variation of the other quarter car model variants.
基金Supported by the National Natural Science Foundation of China No. 90209023
文摘AIM: To investigate electroacupunture(EA) at the acupoints of Stomach Meridian of Foot-Yangming(SMFY), Gallbladder Meridian of Foot-Yangming(SMFY) on gastric mucosal intestinal trefoil factor (ITF) gene expression detection in stress-induced rats with gastric mucosal lesion, and to explore the regulatory mechanism and significance of EA-related gastric mucosal protective effect. METHODS: Forty rats were randomly divided into 4 groups: Blank group, Model group, Model group+EA at acupoints of SMFY group("SMFY group"), and Model group+EA at acupoints of GMFY group(GMFY group). All rats (except blank group) were made model by water immersion and restraint stress (WRS). Then the gastric mucosa tissue in each rat was taken off alter assessment of gastric mucosal lesion index(GUI), and the expression of ITF mRNA of the tissues was detected by reverse transcdption-polymerase chain reaction(RT-PCR) method. RESULTS: Compared with Model group(S4.3± 1.34), the GUI value in SMFY group (31±2.211 decreased significantly(P〈0.01), so did that in GMFY group (39.8± 1.62, P〈0.05), meanwhile GUI value in SMFY group was significantly lower than in GMFY group(P〈0.01). Compared with Model group (0.65±0.01), EA had a tendency to improve the expression of gastric mucosal ITFmRNA gene: such tendency existed in GMFY group (0.66±0.01) but with no signficant difference(P〉 0.05), in SMFY group(0.76±0.01) with an extremely obvious difference (P〈0.01), furthermore the expression in SMFY group was significantly higher than in GMFY group (P〈 0.01).CONCLUSION: The gastric mucosal protective effect by EA at the acupoints of SMFY and GMFY was related to the expression variance of ITF, indicating certain meridian specificity exists, It could be one proof for the TCM theory "Relative pardcularity between SMFY and stomach".
基金National Natural Science Foundation of China (10572140,10721202)
文摘The deformation work rate can be expressed by the time rate of pair functional potentials which describe the energy of materi- als in terms of atomic bonds and atom embedding interactions. According to Cauchy-Born rule, the relations between the micro- scopic deformations of atomic bonds and electron gas and macroscopic deformation are established. Further, atomic bonds are grouped according to their directions, and atomic bonds in the same direction are simplified as a spring-bundle component. Atom embedding interactions in unit reference volume are simplified as a cubage component. Consequently, a material model com- posed of spring-bundle components and a cubage component is established. Since the essence of damage is the decrease and loss of atomic bonding forces, the damage effect can be reflected by the response functions of these two kinds of components. For- mulating the mechanical responses of two kinds of components, the corresponding elasto-damage constitutive equations are de- rived. Considering that slip is the main plastic deformation mechanism of polycrystalline metals, the slip systems of crystal are extended to polycrystalline, and the slip components are proposed to describe the plastic deformation. Based on the decomposition of deformation gradient and combining the plastic response with the elasto-damage one, the elasto-plastic damage constitutive equations are derived. As a result, a material model iormulated with spring-bundle components, a cubage component and slip components is established. Different from phenomenological constitutive theories, the mechanical property of materials depends on the property of components rather than that directly obtained on the representative volume element. The effect of finite deformation is taken into account in this model. Parameter calibration procedure and the basic characteristics of this model are discussed.
基金supported by the National Natural Science Foundation of China (No. 40606027)the Project of the Xiamen Science and Technology Program (No. 2013Z20134027)
文摘The toxic effects of tributyltin(TBT) have been extensively documented in several types of cells, but the molecular mechanisms related to the genotoxic effects of TBT have still not been fully elucidated. Our study showed that exposure of human hepatoma G2 cells to 1–4 μmol/L TBT for 3 hr caused severe DNA damage in a concentration-dependent manner. Moreover, the expression levels of key DNA damage sensor genes such as the replication factor C, proliferating cell nuclear antigen and poly(ADP-ribose)polymerase-1 were inhabited in a concentration-dependent manner. We further demonstrated that TBT induced cell apoptosis via the p53-mediated pathway, which was most likely activated by the ataxia telangiectasia mutated and rad-3 related(ATR)protein kinase. The results also showed that cytochrome c, caspase-3, caspase-8,caspase-9, and the B-cell lymphoma 2 were involved in this process. Taken together, we demonstrated for the first time that the inhibition of the DNA repair system might be more responsible for TBT-induced genotoxic effects in cells. Then the generated DNA damage induced by TBT initiated ATR-p53-mediated apoptosis.