AIM: To study the anti-HBV effect of liposome-encapsulated matrine (Lip-M) in vitro and in vivo. METHODS: 2.2.15 cell line was cultured in vitro observe the effect of Lip-M and matrine on the secretion of HBsAg and HB...AIM: To study the anti-HBV effect of liposome-encapsulated matrine (Lip-M) in vitro and in vivo. METHODS: 2.2.15 cell line was cultured in vitro observe the effect of Lip-M and matrine on the secretion of HBsAg and HBeAg. The toxicity of Lip-M and matrine to 2.2.15 cell line was also studied by MTT method. In in vivo study, drug treatment experiment was carried out on the 13th day after ducks were infected with duck hepatitis B virus (DHBV). The ducks were randomly divided into 4 groups with 5-6 ducks in each group. Lip-M and matrine were given to DHBV-infected ducks respectively by gastric perfusion. Four groups were observed: group of Lip-M (20 mg/kg), group of Lip-M (10 mg/kg), group of matrine (20 mg/kg) and group of blank model. The drug was given once daily for 20 d continuously, and normal saline was used as control. The blood was drawn from the posterior tibial vein of all ducks before treatment (T0), after the medication for 5 (T5), 10 (T10), 15 (T15), 20 (T20) d and withdrawl of the drug for 3 d (P3). The serum samples were separated and stored at -70 ℃, DHBV-DNA was detected by the dot-blot hybridization. RESULTS: After addition of Lip-M and matrine to 2.2.15 cell line for eleven d, the median toxic concentration (TC50) of Lip-M and matrine was 7.29 mg/mL and 1.33 mg/mL respectively. The median concentration (IC50) of Lip-M to inhibit HBsAg and HBeAg expression was 0.078 mg/mL and 3.35 mg/mL respectively. The treatment index (TI) value of Lip-M for HBsAg and HBeAg was 93.46 and 2.17 respectively, better than that of matrine. The DHBV-infected duck model treatment test showed that the duck serum DHBV-DNA levels were markedly reduced in the group of Lip-M (20 mg/kg) after treated by gastric perfusion for 10, 15 and 20 d (0.43±0.22 vs 0.95±0.18, t = 4.70, P= 0.001<0.01.0.40±0.12 vs 0.95±0.18, t = 6.34, P= 0.000<0.01. 0.22±0.10 vs 0.95±0.18, t = 8.30, P= 0.000<0.01), compared to the group of matrine (20 mg/kg) (0.43±0.22 vs 0.79±0.19, t = 3.17, P= 0.01<0.05. 0.40±0.12 vs 0.73±0.24, t = 3.21, P= 0.009<0.05. 0.22±0.10 vs0.55±0.32, t = 2.27, P= 0.046<0.05.), and the control (0.43±0.22 vs50.98±0.29, t = 3.68, P = 0.005<0.01. 0.40±0.12 vs 0.97±0.30, t = 4.26, P= 0.002<0.01. 0.22±0.10 vs 0.95±0.27, t = 5.76, P= 0.000<0.01). After the treatment for 20 d and withdrawl of the drug for 3 d, duck serum DHBV-DNA level in the group of Lip-M (10 mg/kg) markedly reduced (0.56±0.26 vs0.95±0.38, t = 5.26, P= 0.003<0.05. 0.55±0.25 vs 0.95±0.38, t = 5.52, P= 0.003<0.05), and the difference was significant as compared with the control (0.56±0.26 vs 0.95±0.27, t = 2.37, P = 0.042<0.05. 0.55±0.25 vs 0.89±0.18, t = 2.55, P= 0.031<0.05), but not significant as compared with the group of matrine (20 mg/kg). After withdrawl of the drug for 3 d, the levels of DHBV-DNA did not relapse in both groups of Lip-M. CONCLUSION: Lip-M can evidently inhibit the replication of hepatitis B virus In vitro and in viva, its anti-HBV effect is better than that of matrine.展开更多
The unique characteristics of gas-solids two-phase flow and fluidization in terms of the flow structures and the apparent behavior of particles and fluid-particle interactions are closely linked to physical properties...The unique characteristics of gas-solids two-phase flow and fluidization in terms of the flow structures and the apparent behavior of particles and fluid-particle interactions are closely linked to physical properties of the particles, operating conditions and bed configurations. Fluidized beds behave quite differently when solid properties, gas velocities or vessel geometries are varied. An understanding of hydrodynamic changes and how they, in turn, influence the transfer and reaction characteristics of chemical and thermal operations by variations in gas-solid contact, residence time, solid circulation and mixing and gas distribution is very important for the proper design and scale-up of fluidized bed reactors. In this paper, rather than attempting a comprehensive survey, we concentrate on examining some important positive and negative impacts of particle sizes, bubbles, clusters and column walls on the physical and chemical aspects of chemical reactor performance from the engineering application point of view with the aim of forming an adequate concept for guiding the design of multiphase fluidized bed chemical reactors. One unique phenomenon associated with particle size is that fluidized bed behavior does not always vary monotonically with changing the average particle size. Different behaviors of particles with difference sizes can be well understood by analyzing the relationship between particle size and various forces. For both fine and coarse particles, too narrow a distribution is generally not favorable for smooth fluidization. A too wide size distribution, on the other hand, may lead to particle segregation and high particle elutriation. Good fluidization performance can be established with a proper size distribution in which inter-particle cohesive forces are reduced by the lubricating effect of fine particles on coarse particles for Type A, B and D particles or by the spacing effect of coarse particles or aggregates for Type C powders. Much emphasis has been paid to the negative impacts of bubbles, such as gas bypassing through bubbles, poor bub-ble-to-dense phase heat & mass transfer, bubble-induced large pressure fluctuations, process instabilities, catalyst attrition and equipment erosion, and high entrainment of particles induced by erupting bubbles at the bed surface. However, it should be noted that bubble motion and gas circulation through bubbles, together with the motion of particles in bubble wakes and clouds, contribute to good gas and solids mixing. The formation of clusters can be attributed to the movement of trailing particles into the low-pressure wake region of leading particles or clusters. On one hand, the existence of down-flowing clusters induces strong solid back-mixing and non-uniform radial distributions of particle velocities and holdups, which is undesirable for chemical reactions. On the other hand, the formation of clusters creates high solids holdups in the riser by inducing internal solids circulations, which are usually beneficial for increasing concentrations of solid catalysts or solid reactants. Wall effects have widely been blamed for complicating the scale-up and design of fluidized-bed reactors. The decrease in wall friction with increasing the column diameter can significantly change the flow patterns and other important characteristics even under identical operating conditions with the same gas and particles. However, internals, which can be considered as a special wall, have been used to improve the fluidized bed reactor performance. Generally, desirable and undesirable dual characteristics of interaction between particles and fluid are one of the important natures of multiphase flow. It is shown that there exists a critical balance between those positive and negative impacts. Good fluidization quality can always be achieved with a proper choice of right combinations of particle size and size distribution, bubble size and wall design to alleviate the negative impacts.展开更多
基金Supported by the Natural Science Foundation of Guangdong Province, No.B990353
文摘AIM: To study the anti-HBV effect of liposome-encapsulated matrine (Lip-M) in vitro and in vivo. METHODS: 2.2.15 cell line was cultured in vitro observe the effect of Lip-M and matrine on the secretion of HBsAg and HBeAg. The toxicity of Lip-M and matrine to 2.2.15 cell line was also studied by MTT method. In in vivo study, drug treatment experiment was carried out on the 13th day after ducks were infected with duck hepatitis B virus (DHBV). The ducks were randomly divided into 4 groups with 5-6 ducks in each group. Lip-M and matrine were given to DHBV-infected ducks respectively by gastric perfusion. Four groups were observed: group of Lip-M (20 mg/kg), group of Lip-M (10 mg/kg), group of matrine (20 mg/kg) and group of blank model. The drug was given once daily for 20 d continuously, and normal saline was used as control. The blood was drawn from the posterior tibial vein of all ducks before treatment (T0), after the medication for 5 (T5), 10 (T10), 15 (T15), 20 (T20) d and withdrawl of the drug for 3 d (P3). The serum samples were separated and stored at -70 ℃, DHBV-DNA was detected by the dot-blot hybridization. RESULTS: After addition of Lip-M and matrine to 2.2.15 cell line for eleven d, the median toxic concentration (TC50) of Lip-M and matrine was 7.29 mg/mL and 1.33 mg/mL respectively. The median concentration (IC50) of Lip-M to inhibit HBsAg and HBeAg expression was 0.078 mg/mL and 3.35 mg/mL respectively. The treatment index (TI) value of Lip-M for HBsAg and HBeAg was 93.46 and 2.17 respectively, better than that of matrine. The DHBV-infected duck model treatment test showed that the duck serum DHBV-DNA levels were markedly reduced in the group of Lip-M (20 mg/kg) after treated by gastric perfusion for 10, 15 and 20 d (0.43±0.22 vs 0.95±0.18, t = 4.70, P= 0.001<0.01.0.40±0.12 vs 0.95±0.18, t = 6.34, P= 0.000<0.01. 0.22±0.10 vs 0.95±0.18, t = 8.30, P= 0.000<0.01), compared to the group of matrine (20 mg/kg) (0.43±0.22 vs 0.79±0.19, t = 3.17, P= 0.01<0.05. 0.40±0.12 vs 0.73±0.24, t = 3.21, P= 0.009<0.05. 0.22±0.10 vs0.55±0.32, t = 2.27, P= 0.046<0.05.), and the control (0.43±0.22 vs50.98±0.29, t = 3.68, P = 0.005<0.01. 0.40±0.12 vs 0.97±0.30, t = 4.26, P= 0.002<0.01. 0.22±0.10 vs 0.95±0.27, t = 5.76, P= 0.000<0.01). After the treatment for 20 d and withdrawl of the drug for 3 d, duck serum DHBV-DNA level in the group of Lip-M (10 mg/kg) markedly reduced (0.56±0.26 vs0.95±0.38, t = 5.26, P= 0.003<0.05. 0.55±0.25 vs 0.95±0.38, t = 5.52, P= 0.003<0.05), and the difference was significant as compared with the control (0.56±0.26 vs 0.95±0.27, t = 2.37, P = 0.042<0.05. 0.55±0.25 vs 0.89±0.18, t = 2.55, P= 0.031<0.05), but not significant as compared with the group of matrine (20 mg/kg). After withdrawl of the drug for 3 d, the levels of DHBV-DNA did not relapse in both groups of Lip-M. CONCLUSION: Lip-M can evidently inhibit the replication of hepatitis B virus In vitro and in viva, its anti-HBV effect is better than that of matrine.
文摘The unique characteristics of gas-solids two-phase flow and fluidization in terms of the flow structures and the apparent behavior of particles and fluid-particle interactions are closely linked to physical properties of the particles, operating conditions and bed configurations. Fluidized beds behave quite differently when solid properties, gas velocities or vessel geometries are varied. An understanding of hydrodynamic changes and how they, in turn, influence the transfer and reaction characteristics of chemical and thermal operations by variations in gas-solid contact, residence time, solid circulation and mixing and gas distribution is very important for the proper design and scale-up of fluidized bed reactors. In this paper, rather than attempting a comprehensive survey, we concentrate on examining some important positive and negative impacts of particle sizes, bubbles, clusters and column walls on the physical and chemical aspects of chemical reactor performance from the engineering application point of view with the aim of forming an adequate concept for guiding the design of multiphase fluidized bed chemical reactors. One unique phenomenon associated with particle size is that fluidized bed behavior does not always vary monotonically with changing the average particle size. Different behaviors of particles with difference sizes can be well understood by analyzing the relationship between particle size and various forces. For both fine and coarse particles, too narrow a distribution is generally not favorable for smooth fluidization. A too wide size distribution, on the other hand, may lead to particle segregation and high particle elutriation. Good fluidization performance can be established with a proper size distribution in which inter-particle cohesive forces are reduced by the lubricating effect of fine particles on coarse particles for Type A, B and D particles or by the spacing effect of coarse particles or aggregates for Type C powders. Much emphasis has been paid to the negative impacts of bubbles, such as gas bypassing through bubbles, poor bub-ble-to-dense phase heat & mass transfer, bubble-induced large pressure fluctuations, process instabilities, catalyst attrition and equipment erosion, and high entrainment of particles induced by erupting bubbles at the bed surface. However, it should be noted that bubble motion and gas circulation through bubbles, together with the motion of particles in bubble wakes and clouds, contribute to good gas and solids mixing. The formation of clusters can be attributed to the movement of trailing particles into the low-pressure wake region of leading particles or clusters. On one hand, the existence of down-flowing clusters induces strong solid back-mixing and non-uniform radial distributions of particle velocities and holdups, which is undesirable for chemical reactions. On the other hand, the formation of clusters creates high solids holdups in the riser by inducing internal solids circulations, which are usually beneficial for increasing concentrations of solid catalysts or solid reactants. Wall effects have widely been blamed for complicating the scale-up and design of fluidized-bed reactors. The decrease in wall friction with increasing the column diameter can significantly change the flow patterns and other important characteristics even under identical operating conditions with the same gas and particles. However, internals, which can be considered as a special wall, have been used to improve the fluidized bed reactor performance. Generally, desirable and undesirable dual characteristics of interaction between particles and fluid are one of the important natures of multiphase flow. It is shown that there exists a critical balance between those positive and negative impacts. Good fluidization quality can always be achieved with a proper choice of right combinations of particle size and size distribution, bubble size and wall design to alleviate the negative impacts.
