中药栀子超临界萃取物的挥发性成分研究

研究了栀子萃取的最佳工艺条件及其挥发油中的化学成分。以L9（3^4）正交设计对超临界萃取条件进行优化，GC-MS联用技术对挥发性成分进行定性及半定量分析。结果显示：55℃，35MPa，120min的萃取条件下挥发性成分的收率最高，超临界萃取产物的主要成分为亚油酸，棕榈酸，反，反-2，4-癸二烯醛，而传统水蒸汽蒸馏工艺下主要成分为反，反-2，4-癸二烯醛。与水蒸汽蒸馏工艺相比较。超临界流体萃取工艺且有革取率高。生产周期短的优点．     

基于系统输出分布的智能控制

提出了文题所述的控制策略,依据输出分布曲线的特征变量选取方法和依据该项信息的规则控制系统。仿真研究得到了满意的结果。在一个实验性二元精馏塔上用IBM-PC进行试验亦获成功。本法对具有非线性特性的分布参数对象,较常规控制策略有明显的优越性。     

穿破石挥发性成分的研究

目的 :研究穿破石中的挥发性成分。方法 :利用水蒸气蒸馏法提取穿破石挥发油 ,用GC-MS进行测定 ,结合计算机检索技术对分离的化合物进行结构鉴定 ,应用色谱峰面积归一化法计算各成分的相对百分含量。结果 :鉴定出 64个化学成分 ,其中相对百分率含量大于 1%的有23个成分 ,含量较高的是L 芳樟醇 (L-linalool)9.852%。结论 :64个挥发性成分均为首次从该植物中得到。     

千斤拔挥发性成分的研究

目的：研究千斤拔中的挥发性成分。方法：利用水蒸气蒸馏法提取千斤拔(Radix Flemingiae philippinensis）挥发油，用GC—MS进行测定，结合计算机检索技术对分离的化合物进行结构鉴定，应用色谱峰面积归一化法计算各成分的相对百分含量。结果：鉴定出39个化学成分，其中相对百分率含量大于4％的分别确定为α—雪松烯(1)，γ—雪松烯(2)，β—雪松烯(3)，β—愈创烯(4)，Italiccnc(5)。结论：千斤拔挥发油中近80％成分已查清。     

分子蒸馏技术在中药研究中的应用

分子蒸馏技术是近年来应用渐多的一种新的分离纯化技术，在食品和化工行业应用较多，中药研究与开发方面的应用报道不多，我们将这项技术用于新药有效部位研究中，成功地富集了多种超临界萃取物中的有效成分，取得很好的效果。     

Stem water cryogenic extraction biases estimation in deuterium isotope composition of plant source water

The hydrogen isotope ratio of water cryogenically extracted from plant stem samples (δ²H_{stem_CVD}) is routinely used to aid isotope applications that span hydrological, ecological, and paleoclimatological research. However, an increasing number of studies have shown that a key assumption of these applications—that δ²H_{stem_CVD} is equal to the δ²H of plant source water (δ²H_source)—is not necessarily met in plants from various habitats. To examine this assumption, we purposedly designed an experimental system to allow independent measurements of δ²H_{stem_CVD}, δ²H_source, and δ²H of water transported in xylem conduits (δ²H_xylem) under controlled conditions. Our measurements performed on nine woody plant species from diverse habitats revealed a consistent and significant depletion in δ²H_{stem_CVD} compared with both δ²H_source and δ²H_xylem. Meanwhile, no significant discrepancy was observed between δ²H_source and δ²H_xylem in any of the plants investigated. These results cast significant doubt on the long-standing view that deuterium fractionation occurs during root water uptake and, alternatively, suggest that measurement bias inherent in the cryogenic extraction method is the root cause of δ²H_{stem_CVD} depletion. We used a rehydration experiment to show that the stem water cryogenic extraction error could originate from a dynamic exchange between organically bound deuterium and liquid water during water extraction. In light of our finding, we suggest caution when partitioning plant water sources and reconstructing past climates using hydrogen isotopes, and carefully propose that the paradigm-shifting phenomenon of ecohydrological separation (“two water worlds”) is underpinned by an extraction artifact.

The analysis of the stable isotope ratios of plant source water (δ_source) is a powerful tool enabling the elucidation of a range of plant physiological, ecological, and hydrological processes from scales ranging from individual plants to the planet. δ_source provides a foundation on which to form isotope signals of transpired water vapor and plant-derived biomarkers (i.e., cellulose and lipids) and thus is of high relevance to studies of terrestrial water fluxes (1, 2) and paleoclimate reconstructions (3, 4). δ_source also contains information on the spatial and temporal origins of water used by plants and so is commonly used for investigating plant water uptake patterns under natural conditions (5, 6). Moreover, dual-isotope (δ²H and δ¹⁸O) analysis of δ_source was critical in formulating the paradigm-shifting “two water worlds” (TWW) hypothesis, whereby ecohydrological separation exists between plant-accessible soil water pools and those recharging streams and groundwater (7, 8).Elucidation of the foregoing processes rest on the assumption that water extracted from plant stems is isotopically identical to water taken up by plant roots. Plant stem water is typically extracted with the cryogenic-vacuum distillation technique; δ generated with this method is hereinafter referred as δ_{stem_CVD} (9). For δ_{stem_CVD} to be an accurate indicator of δ_source (i.e., δ_{stem_CVD} = δ_source), two prerequisites must be met: 1) isotope change does not occur during root uptake and/or xylem transport of the source water (prerequisite I) and 2) stem water cryogenic extraction is a robust approach toward isotope recovery of xylem water (prerequisite II). The “δ_{stem_CVD} = δ_source” assumption is generally valid for oxygen isotopes of water, but numerous studies have used hydrogen isotopes to assess source water, and here this assumption has faced scrutiny, as multiple studies have reported significant depletion in δ²H_{stem_CVD} compared with δ²H_source in plants from various habitats (10–18).A frequently invoked explanation for the observed δ²H_{stem_CVD} depletion is a violation of prerequisite I, as it is believed that symplastic uptake of source water into the root xylem can give rise to hydrogen isotope fractionation (10, 11, 13, 19). The available evidence (10, 11) in support of such an explanation is largely peripheral, because direct, unambiguous confirmation of water uptake/transport-related fractionation would require a comparison of deuterium in source water and water transported within xylem conduits (δ²H_xylem). However, this type of comparison is difficult owing to the technical challenges in obtaining targeted measurements of δ²H_xylem in most plants. Intriguingly, in a field-grown riparian tree species (Populus euphratica) in which δ²H_xylem measurement was made possible with the aid of a syringe-aided xylem sap bleeding technique, no significant difference was observed between δ²H_xylem and δ²H_source (12). This led to the suggestion that, at least for the investigated species, δ²H_{stem_CVD} depletion arises not from a violation of prerequisite I, but rather from a violation of prerequisite II. The violation of prerequisite II has been deemed possible (12, 17) based on the argument that hydrogen isotope heterogeneity could be present within the bulk stem water (i.e., the outside xylem water may carry a metabolism-induced, more-depleted δ²H signature compared with the xylem water), potentially causing the stem water extraction technique to artifactually underestimate δ²H_xylem.Given the controvertible state of knowledge regarding the mechanism driving δ²H_{stem_CVD} depletion, it is imperative for us to build a better and more comprehensive understanding of the isotopic relationships among cryogenic extracted bulk stem water, source water, and xylem water in different plants, so as to put the application of the stem water cryogenic extraction technique in diverse fields on firmer ground. In this context, it should be pointed out that the xylem water direct sampling technique (12) is applicable only to a few riparian tree species. Recently, a new method relying on laser-enabled isotope measurement of water vapor in equilibrium with xylem water has demonstrated potential for in situ continuous monitoring of xylem isotope signatures in trees (20, 21); however, the method needs further development before it becomes broadly applicable to different plant types. Thus, a more generally applicable method is needed for determining xylem water signature across diverse plant types.Toward this goal, and capitalizing on the well-recognized mass balance-dictated principle that the isotopic composition of steady-state (SS) plant transpiration is identical to that of the xylem water supplying the plant canopy, we custom-designed a measurement system to enable independent quantification of xylem water isotope composition through isotope measurement of SS plant transpiration. This measurement system conferred the ability to compare values of δ_{stem_CVD}, δ_source, and δ_xylem across a number of plant species of varying native habitats. The data allowed us to confirm the common presence of δ²H_{stem_CVD} depletion across all plant types measured, and also to demonstrate that this phenomenon is caused by cryogenic extraction-associated artifact and not by water uptake/transport-related fractionation. We also performed a rehydration experiment to illustrate that the extraction artifact is unrelated to within-stem isotope heterogeneity as has been recently suggested, but rather is more likely linked to a deuterium-exchange process that occurs dynamically during cryogenic extraction. Using the TWW hypothesis as an example, we further discuss the ramifications for ecological/hydrological queries that rely on accurate isotopic information on plant source/xylem water.     

丁香茄挥发油成分GC-MS分析

目的分析丁香茄中挥发油的化学成分。方法采用水蒸气蒸馏法提取丁香茄中挥发油,用GC-MS法测定和分析其化学组分。结果共鉴定了19个成分,占总峰面积的96%,按相对峰面积计,其中含亚油酸为62.8%,总脂肪酸和其他酯约占72%。结论丁香茄挥发油的主要成分为脂肪酸,为开发利用丁香茄资源提供了实验依据。     

Industrial separation of oxygen isotopes by oxygen distillation

¹⁸O‐labeled water (Water‐¹⁸O) is a widely used starting material of ¹⁸F‐labeled diagnostic agents in positron emission tomography (PET). Conventionally, Water‐¹⁸O has been separated from other stable oxygen isotope species (¹⁶O, ¹⁷O) by water distillation or nitric oxide distillation. However, conventional methods are costly and may have safety issues. In 2004, we developed the first unit of our novel oxygen isotope separation process by cryogenic oxygen distillation to overcome these issues. To meet the needs of the market, we built a second unit in 2013 and a third in 2016. We are now operating three commercially viable separation units with a total capacity of 600 kg of Water‐¹⁸O per year.