采用超临界流体R ESS法对超细黑索今(RD X)进行了包覆,研究了不同系统温度、溶液浓度、系统压力对包覆后超细RD X造型粉效果的影响,并对其进行撞击感度测试。结果表明,系统温度45℃以上,造型粉颗粒之间氟橡胶粘结在一起,分散性较差;氟...采用超临界流体R ESS法对超细黑索今(RD X)进行了包覆,研究了不同系统温度、溶液浓度、系统压力对包覆后超细RD X造型粉效果的影响,并对其进行撞击感度测试。结果表明,系统温度45℃以上,造型粉颗粒之间氟橡胶粘结在一起,分散性较差;氟橡胶浓度0.4 g/m L以上,其造型粉颗粒尺寸增大;系统压力降低到12 M P a以下,颗粒表面未完全被氟橡胶包覆,且分散性也较差。当系统温度40℃、氟橡胶浓度0.3 g/m L、系统压力14 M P a、通气时间20 m in条件下,包覆效果最好。包覆后样品撞击感度特性落高比超细RD X(25.2 cm)提高了9.48 cm。展开更多
采用常规、简便的喷射装置,建立了一套超临界溶液快速膨胀(Rapid Expansion of Supercritical Solutions,RESS)实验装置。该装置能有效地防止堵塞。以CO2为溶剂,萘为溶质,考察了喷嘴直径及收集距离对沉积微粒粒径的影响,研究了在不同的...采用常规、简便的喷射装置,建立了一套超临界溶液快速膨胀(Rapid Expansion of Supercritical Solutions,RESS)实验装置。该装置能有效地防止堵塞。以CO2为溶剂,萘为溶质,考察了喷嘴直径及收集距离对沉积微粒粒径的影响,研究了在不同的收集距离时粒径随溶液浓度的变化规律。结果表明喷嘴直径增大将使产物粒子粒径增大;在50mm的范围内,产物粒径随着收集距离的增加而明显增加,结果也显示出RESS产物是通过更小粒子之间的碰撞凝结而生长。当收集距离较大时,晶体的生长过程相比于晶核的形成过程对沉积微粒的粒径影响更大,故粒子粒径随溶液浓度增加而增大;当收集距离较小时,晶核的形成过程占主导地位,因此产物粒径随溶液浓度的增加而减小,符合经典成核理论。展开更多
通过对超临界流体快速膨胀法(rapid expansion of supercritical solution,RESS)流动过程的简化与分析,建立了喷嘴节流流动过程模型,一维定常过程数学模型的描述包括了锥体入口段、直管膨胀段和到达马赫盘位置的出口超音速膨胀段.给出...通过对超临界流体快速膨胀法(rapid expansion of supercritical solution,RESS)流动过程的简化与分析,建立了喷嘴节流流动过程模型,一维定常过程数学模型的描述包括了锥体入口段、直管膨胀段和到达马赫盘位置的出口超音速膨胀段.给出了模型中的主要计算参数来源以及解算过程的基本思路.据此模型,在给定初值条件下,对各个阶段的流动状态进行模拟计算,得到了流体的密度、压力、温度、速度等参数沿喷嘴轴向的变化数据,并进行了初步验证.该模型和模拟过程能够为实现制备均一微细颗粒的实际操作条件和优化过程参数奠定基础.展开更多
Griseofulvin (GF) is an antifungal drug whose pharmaceutical activity can be improved by reducing particle size. In this study the rapid expansion of supercritical solution (RESS) was employed to micronize GF.Carbon d...Griseofulvin (GF) is an antifungal drug whose pharmaceutical activity can be improved by reducing particle size. In this study the rapid expansion of supercritical solution (RESS) was employed to micronize GF.Carbon dioxide with cosolvent acetone was chosen as a supercritical mixed solvent. The solubility of GF in super-critical CO2 with cosolvent acetone was measured using a dynamic apparatus at pressures between 12 and 32 MPa,temperatures at 313, 323 and 333 K and cosolvent concentration at 1.5, 3.0, 4.5 and 6.0% (by mole). The effect of pre-expansion pressure, extraction temperature, spraying distance, nozzle size and concentration of cosolvent on the precipitated particles was investigated. The results show that the mean particle size of griseofulvin precipitated by RESS was less than 1.2μm. An increase in pre-expansion pressure, extraction temperature, spraying distance and concentration of cosolvent resulted in a decrease in particle size under the operating condition studied. With the decrease of nozzle diameter the particle size reduces. The crystallinity and melting point of the original material and the processed particle by RESS were tested by X-ray diffraction (XRD) and differential scanning calorimetry (DSC).No evident modification in the crystal habit was found under the experimental conditions tested. The morphology of particles precipitated was analyzed bY scanning electron microscopy (SEM).展开更多
The inherent characteristics in the rapid expansion process of supercritical fluid solution were analyzed. The temperature change resulted from the throttling expansion of the supercritical fluid, and the strong turbu...The inherent characteristics in the rapid expansion process of supercritical fluid solution were analyzed. The temperature change resulted from the throttling expansion of the supercritical fluid, and the strong turbulence in the expansion flow resulted from the quick change of the fluid pressure were experimentally measured. It was proposed that the temperature and turbulence in the expansion flow affect the particle nucleation, growth or coating process significantly.展开更多
Purpose To summarize the major achievements of Chinese work on the epid emiology and prevention of hemorrhagic fever with renal syndrome (HFRS) in recen t years, and to give a general review on the present situation ...Purpose To summarize the major achievements of Chinese work on the epid emiology and prevention of hemorrhagic fever with renal syndrome (HFRS) in recen t years, and to give a general review on the present situation of HFRS in China.Data sources Reviews and papers published in Chinese journals, relevant to the objectives, written or collected by the author; and the research work of the author.Study selection An outline was drafted according to the purpose given a bove, and the relevant materials and data were grouped together into different i tems outlined.Data extraction All the materials and data extracted were published or specially assessed.Results HFRS was first recognized in the northeastern China in 1931. It has been found prevalent also in many other parts of China since 1955, and p resently, 28 out of 31 provinces (autonomous regions, or municipalities) have b een proved to be its endemic areas. The total number of cases is 1?256?431 from 1950 to 1997, with 44?304 death (3.53%). 50-100 thousands of cases co uld be registered annually since 1981 when the presence of the Rattus type HFRS wa s first identified serologically in China, with the highest peak in 1986 ( 115 ?985 cases). Three types of endemicity have been differentiated: the Apodemus type, the Rattus type and the mixed type of the two, by their peculiar season al distributions of cases and by methods of serotyping (HI, MAbs serotyping kits ). The epidemiologic features of the Rattus type HFRS are quite different from that of the Apodemus type. 67 species of vertebrates were found to harbor hanta virus antigen or antibodies, but the chief or primary reservoir hosts are A podemus agrarius and Rattus norveg icus only. Besides the commonly recognized enzootic mode of transmission (via co ntact s with the reservoir rodents or their excreta), mite transmission (including cer tain species of gamasid mites, and chigger mites) has been identified as the po tential vectors and reservoir hosts with HFRS. Vertical transmission had been fo un d in pregnant patients with HFRS, and in all three chief host rodents (Apodemus agr arius, Rattus norvegicus, the laboratory rats). The relatively high inapparent i nfection rates in the population of endemic areas of the Rattus type HFRS afte r big outbreaks (8%-20%) are suggested to play a significant role in the gradual decl ine of the incidence of HFRS in that areas. Three kinds of inactivated vaccines ag ainst HFRS (the golden hamster kidney cell vaccine, the Mongolian gerbil kidney cell vaccine and the purified suckling mouse brain vaccine) have been successive ly developed and proved highly effective in the prevention of HFRS. Conclusion Chinese workers on the epidemiology and prevention of HFRS i n China have accomplished great achievements since 1981. As the relatively high annu al incidence of HFRS sustained in recent years, control measures have to be reen forced. Many problems of HFRS and hantavirus infections are still not well under stood or unclear, such as the poly host nature, and the multi modes of transmi ssion, the natural history of hantaviruses and their genetic variation occurred in nature etc. The task for effective control of HFRS and the research on its ep idemiology in China should be held on a high priority.展开更多
文摘采用超临界流体R ESS法对超细黑索今(RD X)进行了包覆,研究了不同系统温度、溶液浓度、系统压力对包覆后超细RD X造型粉效果的影响,并对其进行撞击感度测试。结果表明,系统温度45℃以上,造型粉颗粒之间氟橡胶粘结在一起,分散性较差;氟橡胶浓度0.4 g/m L以上,其造型粉颗粒尺寸增大;系统压力降低到12 M P a以下,颗粒表面未完全被氟橡胶包覆,且分散性也较差。当系统温度40℃、氟橡胶浓度0.3 g/m L、系统压力14 M P a、通气时间20 m in条件下,包覆效果最好。包覆后样品撞击感度特性落高比超细RD X(25.2 cm)提高了9.48 cm。
文摘采用常规、简便的喷射装置,建立了一套超临界溶液快速膨胀(Rapid Expansion of Supercritical Solutions,RESS)实验装置。该装置能有效地防止堵塞。以CO2为溶剂,萘为溶质,考察了喷嘴直径及收集距离对沉积微粒粒径的影响,研究了在不同的收集距离时粒径随溶液浓度的变化规律。结果表明喷嘴直径增大将使产物粒子粒径增大;在50mm的范围内,产物粒径随着收集距离的增加而明显增加,结果也显示出RESS产物是通过更小粒子之间的碰撞凝结而生长。当收集距离较大时,晶体的生长过程相比于晶核的形成过程对沉积微粒的粒径影响更大,故粒子粒径随溶液浓度增加而增大;当收集距离较小时,晶核的形成过程占主导地位,因此产物粒径随溶液浓度的增加而减小,符合经典成核理论。
文摘通过对超临界流体快速膨胀法(rapid expansion of supercritical solution,RESS)流动过程的简化与分析,建立了喷嘴节流流动过程模型,一维定常过程数学模型的描述包括了锥体入口段、直管膨胀段和到达马赫盘位置的出口超音速膨胀段.给出了模型中的主要计算参数来源以及解算过程的基本思路.据此模型,在给定初值条件下,对各个阶段的流动状态进行模拟计算,得到了流体的密度、压力、温度、速度等参数沿喷嘴轴向的变化数据,并进行了初步验证.该模型和模拟过程能够为实现制备均一微细颗粒的实际操作条件和优化过程参数奠定基础.
文摘Griseofulvin (GF) is an antifungal drug whose pharmaceutical activity can be improved by reducing particle size. In this study the rapid expansion of supercritical solution (RESS) was employed to micronize GF.Carbon dioxide with cosolvent acetone was chosen as a supercritical mixed solvent. The solubility of GF in super-critical CO2 with cosolvent acetone was measured using a dynamic apparatus at pressures between 12 and 32 MPa,temperatures at 313, 323 and 333 K and cosolvent concentration at 1.5, 3.0, 4.5 and 6.0% (by mole). The effect of pre-expansion pressure, extraction temperature, spraying distance, nozzle size and concentration of cosolvent on the precipitated particles was investigated. The results show that the mean particle size of griseofulvin precipitated by RESS was less than 1.2μm. An increase in pre-expansion pressure, extraction temperature, spraying distance and concentration of cosolvent resulted in a decrease in particle size under the operating condition studied. With the decrease of nozzle diameter the particle size reduces. The crystallinity and melting point of the original material and the processed particle by RESS were tested by X-ray diffraction (XRD) and differential scanning calorimetry (DSC).No evident modification in the crystal habit was found under the experimental conditions tested. The morphology of particles precipitated was analyzed bY scanning electron microscopy (SEM).
基金Supported by the National Natural Science Foundation of China(No.29906004)
文摘The inherent characteristics in the rapid expansion process of supercritical fluid solution were analyzed. The temperature change resulted from the throttling expansion of the supercritical fluid, and the strong turbulence in the expansion flow resulted from the quick change of the fluid pressure were experimentally measured. It was proposed that the temperature and turbulence in the expansion flow affect the particle nucleation, growth or coating process significantly.
文摘Purpose To summarize the major achievements of Chinese work on the epid emiology and prevention of hemorrhagic fever with renal syndrome (HFRS) in recen t years, and to give a general review on the present situation of HFRS in China.Data sources Reviews and papers published in Chinese journals, relevant to the objectives, written or collected by the author; and the research work of the author.Study selection An outline was drafted according to the purpose given a bove, and the relevant materials and data were grouped together into different i tems outlined.Data extraction All the materials and data extracted were published or specially assessed.Results HFRS was first recognized in the northeastern China in 1931. It has been found prevalent also in many other parts of China since 1955, and p resently, 28 out of 31 provinces (autonomous regions, or municipalities) have b een proved to be its endemic areas. The total number of cases is 1?256?431 from 1950 to 1997, with 44?304 death (3.53%). 50-100 thousands of cases co uld be registered annually since 1981 when the presence of the Rattus type HFRS wa s first identified serologically in China, with the highest peak in 1986 ( 115 ?985 cases). Three types of endemicity have been differentiated: the Apodemus type, the Rattus type and the mixed type of the two, by their peculiar season al distributions of cases and by methods of serotyping (HI, MAbs serotyping kits ). The epidemiologic features of the Rattus type HFRS are quite different from that of the Apodemus type. 67 species of vertebrates were found to harbor hanta virus antigen or antibodies, but the chief or primary reservoir hosts are A podemus agrarius and Rattus norveg icus only. Besides the commonly recognized enzootic mode of transmission (via co ntact s with the reservoir rodents or their excreta), mite transmission (including cer tain species of gamasid mites, and chigger mites) has been identified as the po tential vectors and reservoir hosts with HFRS. Vertical transmission had been fo un d in pregnant patients with HFRS, and in all three chief host rodents (Apodemus agr arius, Rattus norvegicus, the laboratory rats). The relatively high inapparent i nfection rates in the population of endemic areas of the Rattus type HFRS afte r big outbreaks (8%-20%) are suggested to play a significant role in the gradual decl ine of the incidence of HFRS in that areas. Three kinds of inactivated vaccines ag ainst HFRS (the golden hamster kidney cell vaccine, the Mongolian gerbil kidney cell vaccine and the purified suckling mouse brain vaccine) have been successive ly developed and proved highly effective in the prevention of HFRS. Conclusion Chinese workers on the epidemiology and prevention of HFRS i n China have accomplished great achievements since 1981. As the relatively high annu al incidence of HFRS sustained in recent years, control measures have to be reen forced. Many problems of HFRS and hantavirus infections are still not well under stood or unclear, such as the poly host nature, and the multi modes of transmi ssion, the natural history of hantaviruses and their genetic variation occurred in nature etc. The task for effective control of HFRS and the research on its ep idemiology in China should be held on a high priority.
