Dispersion polymerizations in supercritical carbon dioxide

Conventional heterogeneous dispersion polymerizations of unsaturated monomers are performed in either aqueous or organic dispersing media with the addition of interfacially active agents to stabilize the colloidal dispersion that forms. Successful stabilization of the polymer colloid during polymerization results in the formation of high molar mass polymers with high rates of polymerization. An environmentally responsible alternative to aqueous and organic dispersing media for heterogeneous dispersion polymerizations is described in which supercritical carbon dioxide (CO(2)) is used in conjunction with molecularly engineered free radical initiators and amphipathic molecules that are specifically designed to be interfacially active in CO(2). Conventional lipophilic monomers, exemplified by methyl methacrylate, can be quantitatively (>90 percent) polymerized heterogeneously to very high degrees of polymerization (>3000) in supercritical CO(2) in the presence of an added stabilizer to form kinetically stable dispersions that result in micrometer-sized particles with a narrow size distribution.     

东方1-1气田CO2长距离管道输送参数优化

从相态控制角度,以东方1-1气田在海南岛陆上终端排放的CO2为例,开展了CO2长距离管输压力和管径的优化研究,并对管道入口压力、入口温度及环境温度等因素进行敏感性分析。结果表明：管输压力对CO2的输送相态具有重要影响,且很大程度上决定管径和壁厚,进而影响管道经济性;管输压力应保持在CO2临界压力之上,在无保温措施的情况下,CO2始终呈高压密相状态（超临界状态或液态）,能保持管道的正常运行;对于东方1-1气田伴生CO2长距离输送方案,推荐管输压力为9MPa或16MPa,管材采用X65钢,不必采取保温措施。（图4,参14）     

Supernova remnant OH masers: signposts of cosmic collision

A supernova explosion, the final death throe of a massive star, creates an expanding bubble of hot gas that overruns up the surrounding medium. When a supernova remnant encounters a dense interstellar cloud, the compression may trigger gravitational collapse and the formation of a new generation of stars. This event can be detected through intense stimulated emission in the 1720-megahertz transition of the hydroxyl radical, OH, which yields unique insights into the physical processes and conditions occurring during the interaction.     

二氧化碳的低温储存和运输

分析了国内使用常温高压气瓶储运ＣＯ２存在的不足，根据国外ＣＯ２低温储运技术，介绍了天然ＣＯ２的低温液化过程和ＣＯ２低温储运的工艺流程，通过分析计算认为，选用Ｓ８－１２．５Ａ单机双级氨制冷压缩机作为主机可满足提供ＣＯ２低温液化所需热量，用ＪＮ－１５１黄河牌汽车底盘、ＣＯ２储罐、仪表箱、增压器及输液软管等改装的低温ＣＯ２罐车，可用于ＣＯ２长途运输。指出采用低温储运ＣＯ２可提高ＣＯ２的充装速度和储运效率     

超临界CO2萃取金柑籽油工艺

研究了超临界CO2萃取金柑籽油的最佳工艺,考察了萃取时间、萃取压力、萃取温度、CO2流量、解析压力、解析温度对萃取效果的影响.试验表明,在萃取温度为40℃、萃取压力为30 MPa、解析压力为10 MPa、解析温度为55℃和CO2流量为15 L·h-1的条件下萃取率可达45.1%.     

不同管径和温压条件下的CO_2管道输送特性

为深入研究CO_2管输特性,以输量为100×104 t/a的CO_2管道工程为例,采用Pipephase仿真软件建模,分别对气相、液相和超临界相3种相态的CO_2在不同管径和温压条件下的输送过程进行模拟。结果表明:气相、液相、超临界相3种管输方式在不同管径下的压降均不大,压降基本只受输送距离的影响;管输CO_2的密度和黏度以气相输送时基本不受输送距离、温度及压力的影响,以液相和超临界相输送时主要受温度影响。管道以气相输送时,应避免在高压和准临界区域运行;以液相输送时,应选择在较高压力下运行;以超临界相输送时,应避免温度压力到达临界点。中长距离、沿线人烟稀少的CO_2管道优先采用超临界相输送;中短距离、沿线人口密度高的CO_2管道优先采用气相输送。     

Supersaturation of gases in water: absence of cavitation on decompression from high pressures

Very high supersaturations ranging from 140 atmospheres for oxygen to more than 270 atmospheres for helium, were produced without Cavitation of the water at atmospheric pressure. Thus, the lower limits for de novo bubble formation are increased substantially over those previously obtained.     

不同相态CO_2管内稳态节流实验

在CO_2管输过程中,节流易导致CO_2温降过大,威胁管道的安全运行。采用自主设计的CO_2节流实验装置,进行了不同相态CO_2管内稳态节流实验,采集管内参数变化情况,分别研究了节流前后压差、节流前CO_2相态及杂质N_2含量对CO_2稳态节流温降的影响。实验结果表明:CO_2的节流温降随节流前后压降的增大而增大,随N_2含量增大而减小;气态CO_2的节流效应最强,超临界态次之,液态CO_2节流效应最弱;节流前压力越大,相同压降的CO_2节流温降越小,节流前压力对气态CO_2节流温降的影响小于液态CO_2。     

超临界CO_2萃取紫苏油的工艺优化研究

[目的]优化超临界CO2萃取技术提取紫苏油的工艺,为开发紫苏资源提供科学依据。[方法]利用超临界CO2流体作为萃取溶剂从紫苏子中提取紫苏油。以紫苏子萃取后的出油率为指标,通过L9(33)正交试验筛选超临界CO2提取紫苏子油的最佳工艺,研究萃取温度、萃取压力、CO2动态流量3种因素对萃取紫苏子油产率的影响。[结果]萃取紫苏子油的最佳工艺为萃取压力20 MPa、萃取温度40℃、CO2动态流量30 L/h。在3种影响因素中,萃取压力的影响作用最显著,CO2动态流量的影响次之,萃取温度影响最小。[结论]采用超临界CO2萃取法提取脂溶性成分具有速度快、效率高和无污染的特点,其溶媒CO2可循环利用,因此,选用超临界CO2萃取法提取紫苏子油非常可行。     

蜂花粉CO2超临界萃取研究

[目的]探讨应用超临界CO2萃取技术萃取蜂花粉。[方法]采用4因素3水平的正交设计法和方差分析,研究萃取温度和萃取压力对萃取效果的影响。[结果]蜂花粉超临界CO2萃取最佳条件:萃取温度50℃、萃取压力20 MPa、分离1温度40℃、分离1压力7 MPa、分离2温度35℃、分离2压力5 MPa、萃取时间3 h。[结论]超临界CO2萃取技术在养蜂生产及蜂产品加工业中有广泛的应用前景,值得进一步研究。     

不同CO_2气腹压力对猫IL-6、CRP和TNF-α的影响

探讨腹腔镜手术中不同CO2气腹压力对猫白细胞介素6(IL-6)、C反应蛋白(CRP)和肿瘤坏死因子-α(TNF-α)的影响。随机挑选60只本地杂种猫,体重2.0~4.0 kg,试验分为6组,设置气腹压力分别为0、4、6、8、10和12 mmHg。分别于气腹前、气腹后90 min、气腹后l、2、3、5 d静脉采血分离血清,检测猫血清中IL-6、CRP、TNF-α的浓度。结果表明,随着CO2气腹通入,IL-6、CRP和TNF-α浓度降低,且气腹压力越大,IL-6、CRP和TNF-α浓度越低;虽然IL-6、CRP和TNF-α浓度在气腹后仍会受其残留气体影响而降低,但相继在术后2~3 d都可恢复到正常水平。表明CO2气腹对机体有一定的影响,进行猫腹腔镜手术时,在保证足够的手术空间下,6 mmHg为最佳气腹压。     

Observational contrains on the global atmospheric co2 budget

Observed atmospheric concentrations of CO(2) and data on the partial pressures of CO(2) in surface ocean waters are combined to identify globally significant sources and sinks of CO(2). The atmospheric data are compared with boundary layer concentrations calculated with the transport fields generated by a general circulation model (GCM) for specified source-sink distributions. In the model the observed north-south atmospheric concentration gradient can be maintained only if sinks for CO(2) are greater in the Northern than in the Southern Hemisphere. The observed differences between the partial pressure of CO(2) in the surface waters of the Northern Hemisphere and the atmosphere are too small for the oceans to be the major sink of fossil fuel CO(2). Therefore, a large amount of the CO(2) is apparently absorbed on the continents by terrestrial ecosystems.     

Arctic lakes and streams as gas conduits to the atmosphere: implications for tundra carbon budgets

Arctic tundra has large amounts of stored carbon and is thought to be a sink for atmospheric carbon dioxide (CO(2)) (0.1 to 0.3 petagram of carbon per year) (1 petagram = 10(15) grams). But this estimate of carbon balance is only for terrestrial ecosystems. Measurements of the partial pressure of CO(2) in 29 aquatic ecosystems across arctic Alaska showed that in most cases (27 of 29) CO(2) was released to the atmosphere. This CO(2) probably originates in terrestrial environments; erosion of particulate carbon plus ground-water transport of dissolved carbon from tundra contribute to the CO(2) flux from surface waters to the atmosphere. If this mechanism is typical of that of other tundra areas, then current estimates of the arctic terrestrial sink for atmospheric CO(2) may be 20 percent too high.     

超临界二氧化碳萃取扁桃油的研究

为了找到用超临界二氧化碳萃取扁桃油的最佳条件 ,采取静态与动态相结合的方式 ,研究了萃取压力、温度及 CO2 体积对扁桃油萃取的影响。结果表明 ,萃取压力为 351 .88kg/cm2、温度为 70℃、CO2 体积4 0 ml时 ,萃取扁桃油效果较好。三因素主次关系为压力 >温度 >CO2 体积。     

应用超临界技术脱除甘蓝红色素异味研究

甘蓝红色素因其异味限制了其在食品行业中的应用,采用超临界技术对甘蓝红色素进行精制脱除异味试验,研究了萃取压力、萃取温度、萃取时间及CO2流量对脱味效果的影响,最终确定在压力20 MPa、温度40℃、CO2流量4 L/h条件下处理3 h,可明显去除甘蓝红异味,色价得率为96.51%。     

一种新型CO2颗粒肥料释放规律的研究

植物的生长是通过光合作用形成碳水化合物并在植物体内积累的过程,CO2是进行光合作用不可缺少的原料。在保护地栽培中,保持适宜的CO2浓度对作物生长起着重要作用,但这基本上是靠人工补充CO2的方法来实现。本试验研究了一种新型CO2颗粒肥的CO2释放规律,测定数据显示了该肥料的CO2释放、放气高峰及其与温度的关系,从而为人工补给CO2提供了理论依据。     

木质部水分中微小气泡平衡稳定性的热力学分析

该文对植物木质部水分中气泡的平衡稳定性进行了热力学分析．从自由能判据的分析进一步证实了力学平衡所做的初步结论：水势较高、压力势较大时，微小气泡能够达到稳定平衡；当水势降低、压力势达到阈值时，气泡则胀大破裂，形成导管中的空腔；并推导出水分压强阈值公式     

CO2在雪层中扩散的模型模拟

利用压力脉动模型对长白山阔叶红松林冬季土壤释放的CO2在雪层中的扩散过程进行模拟,进而估算土壤呼吸。结果表明,由压力脉动引发的空气对流对雪被CO2通量的瞬间影响十分显著,但是当时间达到小时的水平时,空气对流的影响便几乎可以忽略。     

Polar Volatiles on Mars--Theory versus Observation: Excess solid carbon dioxide is probably present in the north residual cap

The residual frost caps of Mars are probably water-ice. They may be the source of the water vapor associated with seasonal polar hoods. A permanent reservoir of solid CO(2) is also probably present within the north residual cap and may comprise a mass of CO(2) some two to five times that of the present atmosphere of Mars. The martian atmospheric pressure is probably regulated by the temperature of the reservoir and not by the annual heat balance of exposed solid CO(2) (37). The present reservoir temperature presumably reflects a long-term average of the polar heat balance. The question of a large permanent north polar cap is reexamined in light of the Mariner 9 data. The lower general elevation of the north polar region compared to the south and the resulting occurrence in the north of a permanent CO(2) deposit are probably responsible for the differences in size and shape of the two residual caps. The details of the processes involved are less apparent, however. It might be argued that the stability of water-ice deposits depends on both insolation and altitude. The present north and south residual caps should be symmetrically located with respect to such a hypothetical stability field. However, the offset of the south cap from the geometrical pole, the non-symmetrical outline of the north cap, and the apparently uniform thickness of the thin, widespread water-ice all argue against control by simple solid-vapor equilibrium of water under present environmental conditions. We think that the present location of the water-ice may reflect, in part, the past location of the permanent CO(2) reservoir. The extreme stability of polar water-ice deposits increases the likelihood that past environmental conditions may be recorded there. Detailed information on elevations in the vicinity of the residual caps is needed before we can further elucidate the nature and history of the residual caps. This, along with measurements of polar infrared emission, should be given high priority in future missions to Mars. Two conclusions follow from the limitation of the mass of solid CO(2) on Mars at present to two to five times the mass of CO(2) in the atmosphere. If all of this CO(2) was entirely sublimated into the atmosphere as a result of hypothetical astronomical or geophysical effects, the average surface pressure would increase to 15 to 30 mbar. Although such a change would have considerable significance for eolian erosion and transportation, there seems to be little possibility that a sufficiently earthlike atmosphere could result for liquid water to become an active erosional agent, as postulated by Milton (38). The pressure broadening required for a green-house effect requires at least 10 to 20 times more pressure (39). If liquid water was ever active in modifying the martian surface, it must have been at an earlier epoch, before the present, very stable CO(2)/H(2)O system developed. There can be no intermittent earthlike episodes now. Furthermore, the present abundance of CO(2) on Mars may be an indicator of the cumulative evolution of volatiles to the surface of the planet (40). Thus, even the possibility of an earlier earth-like episode is dimmed. On Mars, the total CO(2) definitely outgassed has evidently been about 60 +/- 20 g/cm(2). On the earth, about 70 +/- 30 kg/cm(2) of CO(2) have been released to the surface (41). Hence, the total CO(2) devolved by Mars per unit area is about 0.1 percent of that evolved by the earth. Thus, the observational limits we place on solid CO(2) presently located under the north residual cap also may constitute considerable constraints on the total differentiation and devolatilization of the planet. If they are valid, it would seem unlikely that Mars has devolatilized at all like the earth, or ever experienced an earthlike environment on its surface.     

超临界CO_2萃取紫苏油单因素参数的研究

[目的]确定超临界CO2萃取紫苏子油的单因素工艺参数。[方法]采用超临界CO2萃取法提取紫苏子油,通过4因素5水平试验,考察萃取温度、萃取压力、CO2流量、萃取时间对紫苏子出油率的影响。[结果]随着CO2流量的增加,出油率增大,CO2流量在25~30 L/h较合适。随着萃取温度的增加,出油率增大,萃取温度的适宜变化范围为35~40℃。随着萃取压力的增加,出油率增大,萃取压力在20~25 MPa较合适。随着萃取时间的增加,出油率增大,萃取时间的适宜变化范围为1.5~2.0 h。[结论]超临界CO2萃取法提取紫苏子油的单因素试验最佳工艺参数为:CO2流量25~30 L/h,萃取温度35~40℃,萃取压力20~25 MPa,萃取时间1.5~2.0 h。