基于动态露点等温线法的莲子吸湿和解吸特性考察及模型确定＊

目的 考察莲子等温吸湿的吸附与解吸附特性，明确其等温吸湿和解吸规律，以更好地指导莲子的干燥加工和包装储藏，为防止莲子吸水过多而霉变提供数据支持。方法 在25℃条件下，采用基于动态水分吸附法的AQUALAB VSA等温吸湿曲线测定仪记录莲子及其粉末对水分的等温吸附和解吸附曲线，将所得数据采用8种常用模型拟合，引入相关系数（R²）和赤池信息准则（AIC）评价各个模型的准确性和可靠性。结果 25℃时，莲子药材及粉末的吸附和解吸附曲线趋势基本相同，Peleg模型为描述莲子吸附和解吸附特性的最佳模型。结论 通过对莲子等温吸附与解吸附曲线的考察，可以更好地了解中药材吸附与解吸附特性和规律，对指导中药材的合理加工、包装和储藏，保证药材质量和安全具有重要意义。     

Efficiency of Twin-Screw Extrusion of Biodegradable Poly (Butylene Succinate)-Wheat Bran Blend

Unmodified poly (butylene succinate) (PBS) is characterized by very good processability; however, after the incorporation of various fillers of plant origin, its processing becomes much more complicated and its properties are significantly affected. Detailed studies of the processing aspects of PBS/wheat bran (WB) biocomposition are lacking, despite the addition of WB having a significant impact on both the production efficiency and the properties of end products. This research paper presents test results of the co-rotating twin-screw extrusion processing of a biodegradable polymer blend, the matrix of which was PBS, with WB as the filler. In undertaking this task, we examined the impact of extruder screw rotational speed and WB content on the characteristics of extrusion processing, as well as on certain thermal, physical, structural and processing properties of the obtained blend. The WB introduced to the blend was in the form of a selected fraction with particles smaller than 0.2 mm. The measurements were conducted using the Design of Experiment (DOE) methods, which enabled establishing the studied relationships in the form of polynomials and response surfaces. The determined extrusion process characteristics covered the impact of screw rotational speed and WB content on the mass flow rate of the processed blend and its pressure, the screw drive torque and specific energy consumption. The studies of the obtained polymer blend included determining the impact of the aforementioned variable factors on the melt flow rate (MFR) index, chemical structure (FTIR), thermal properties (differential scanning calorimetry (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG)), p-v-T relationships, microstructure, density and moisture absorbance. Analysis of variance (ANOVA) was used to assess the effect of individual variable factors. The results of this work are presented, inter alia, using Pareto charts of standardized effects, which illustrate the influence of individual terms of the determined regression equations on the studied quantity.     

基于质量综合评价的积雪草干燥方法筛选研究

目的探讨不同干燥方式对药材质量的影响,筛选积雪草适宜干燥方法。方法分别采用热风干燥、晒干、晒半干后热风干燥、阴干、微波以及真空干燥对积雪草全草鲜品进行干燥加工,并测定干燥时间和折干率;参考药典方法对积雪草药材性状特征、鉴别、检查、浸出物含量进行分析;采用HPLC法测定样品中积雪草苷、羟基积雪草苷、积雪草酸、羟基积雪草酸、山柰酚-3-O-芸香糖苷、山柰酚和槲皮素的含量;并采用加权评分法进行多指标综合评价排序。结果不同干燥方法耗时差异大,其中晒干、阴干和50℃真空干燥超过100 h,微波干燥低至1.5 h;折干率均值为24.83%;不同干燥方法对药材性状影响主要反映在色泽和气味,其中50～70℃热风干燥色泽较佳,为浅绿色,80、85℃热风干燥和微波干燥气味也发生了显著变化;水分和灰分含量虽有一定差异,但均符合药典标准;干燥方法对浸出物也有一定影响,晒干方式的浸出物含量达到最大,为45.70%,阴干方式的浸出物含量最小,为29.67%;HPLC法测定的7个有效成分含量总和最高的是较为温和的干燥方式阴干,为83.032 mg/g,最低的为75℃热风干燥,为40.982 mg/g;羟基积雪草苷和积雪草苷总和含量最高的为80℃热风干燥,最低的为75℃热风干燥;加权评分排在前3位的分别为70℃热风干燥、晒半干后50℃热风干燥、50℃热风干燥,85℃热风干燥排在末位。结论积雪草产地的适宜干燥方法为70℃热风干燥。     

川麦冬药材中二氧化硫来源及残留积累动态分析

目的:分析川麦冬药材中SO_2来源及残留量积累动态变化,为解决其SO_2残留超标问题提供理论依据。方法:收集主产区不同方法加工的川麦冬药材28份,测定SO_2残留量,根据测定结果对煤炭火烘烤和熏硫2种加工方法在加工过程中川麦冬药材SO_2残留积累动态进行考察。结果:产地收集的28份样品中SO_2残留量超标率35.71%,SO_2来源为煤炭火烘烤和硫磺熏蒸。SO_2残留量和烘烤时间成正比,超标临界时间在8~10 h;SO_2残留量和硫磺熏蒸时间、药材水分含量均呈正比关系,鲜麦冬熏硫1 h后SO_2残留量可高到1 017.69 mg·kg~(-1)。结论:从麦冬药材质量和安全用药考虑,在麦冬产地加工过程中应当禁止熏硫并严格控制煤炭火烘烤时间。     

Evaluation of sampling methods for toxicological testing of indoor air particulate matter

There is a need for toxicity tests capable of recognizing indoor environments with compromised air quality, especially in the context of moisture damage. One of the key issues is sampling, which should both provide meaningful material for analyses and fulfill requirements imposed by practitioners using toxicity tests for health risk assessment. We aimed to evaluate different existing methods of sampling indoor particulate matter (PM) to develop a suitable sampling strategy for a toxicological assay. During three sampling campaigns in moisture-damaged and non-damaged school buildings, we evaluated one passive and three active sampling methods: the Settled Dust Box (SDB), the Button Aerosol Sampler, the Harvard Impactor and the National Institute for Occupational Safety and Health (NIOSH) Bioaerosol Cyclone Sampler. Mouse RAW264.7 macrophages were exposed to particle suspensions and cell metabolic activity (CMA), production of nitric oxide (NO) and tumor necrosis factor (TNFα) were determined after 24?h of exposure. The repeatability of the toxicological analyses was very good for all tested sampler types. Variability within the schools was found to be high especially between different classrooms in the moisture-damaged school. Passively collected settled dust and PM collected actively with the NIOSH Sampler (Stage 1) caused a clear response in exposed cells. The results suggested the higher relative immunotoxicological activity of dust from the moisture-damaged school. The NIOSH Sampler is a promising candidate for the collection of size-fractionated PM to be used in toxicity testing. The applicability of such sampling strategy in grading moisture damage severity in buildings needs to be developed further in a larger cohort of buildings.     

人参提取物吸湿特性及其数学模型

目的拟合人参提取物(GRRE)吸湿过程数学模型并分析其吸湿特性。方法用称量法测试GRRE在25、35、45℃下吸附/解吸等温线,用7个非线性回归方程对等温线进行描述,借助1st Opt统计分析软件拟合,以均方根误差(RMSE)、残差平方和(RSS)和决定系数(R~2)为评价指标,筛选最佳拟合模型,结合25、35、45℃下吸附等温线计算吸附热。结果 25、35、45℃下,GRRE吸附/解吸等温线都是Peleg模型拟合效果较好,都属于第II种类型,解吸等温线因较高的平衡含水量而出现明显的滞后现象,该滞后现象属于H_3型。随着温度升高这种滞后现象变弱。吸附热随着平衡吸湿量的增大而增大。结论 Peleg模型较好地拟合GRRE的吸附/解吸等温线,且吸附/解吸等温线存在滞后现象,该滞后现象随温度升高而变弱,吸附热与平衡吸湿量密切相关。     

Dipalmitoylphosphatidylcholine (DPPC): Annealing Strategy to Mitigate Variability in Thermotropic and Moisture Sorption Behavior

Dipalmitoylphosphatidylcholine (DPPC) demonstrated complex differential scanning calorimetry (DSC) thermal behavior. Transitions below 100°C showed variability in their thermotropic reversibility. An experimental design employing a DSC heat-cool-heat-cool-heat cycle and modulated DSC were used to gain insight into the DPPC's complex thermal nature. An annealing strategy was developed to reduce DPPC's thermotropic variability, moisture uptake rate, and rate variability. Samples annealed at 110°C for 5 min provided a reproducible, thermally reversible material. The annealed material also exhibited an 8-fold decrease in moisture sorption rate and a statistically significant (p = 0.0233) 100-fold decrease in water sorption rate variability compared to DPPC “as is.” An optimized validated stability-indicating high performance liquid chromatography with evaporative light scattering detection method was developed and showed no change in DPPC chemical stability under the annealing treatment conditions.     

阶段降湿对山药热风干燥特性和品质的影响

目的 探索阶段降湿中高湿保持时间及不同降湿工艺对山药热风干燥特性和品质的影响,为提高山药干燥效率和品质及揭示相对湿度的调控依据提供理论基础。方法 研究干燥温度60℃,风速3.0 m/s,相对湿度恒定10%、50%保持不同时间（5、10、20 min）后降为10%、以及相对湿度50%保持10 min后不同降湿干燥工艺（直接降为10%、20%保持20 min后降为10%、30%,20 min,20%,20 min后降为10%、40%,20 min,30%,20 min,20%,20 min后降为10%）,山药片的干燥特性、水分有效扩散系数（D_eff）、色泽、复水比、能耗、多糖含量和微观组织结构。结果 高相对湿度不同保持时间下,相对湿度50%保持10 min相对于恒定10%干燥条件下,干燥时间缩短了20.0%;干燥过程分为升速和降速2个阶段;在10 min时,山药片被充分预热,温度升至45.8℃。不同降湿干燥工艺下,相对湿度50%保持10 min后,阶梯降至10%相对于直接降为10%的干燥条件,干燥时间缩短了25.0%;干燥过程同样分为升速和降速2个阶段;物料温度整体上呈现出缓慢上升的趋势,且均大于其余3者同时期的物料温度;D_eff先慢后快,整个干燥过程平均D_eff最大,为6.77×10^-10 m²/s;此干燥条件下明亮度（L^*）、复水比和多糖含量分别达到其最大值,为（90.76±0.12）、（2.36±0.08）、（57.32±0.21）mg/g,能耗达最低值,为（2.98±0.06）kW·h/kg,且内部形成较明显的水分扩散迁移孔道。结论 高相对湿度有助于强化对物料的传热作用,保持时间应当以物料充分预热为判定依据;阶段降湿干燥过程中,降低相对湿度应当以不降低物料温度为基本约束条件;山药片的恒温阶段降湿干燥过程中,干制后的色泽、复水性、能耗和多糖含量均与干燥时间直接相关;高相对湿度有助于保持和形成物料内部的多孔结构,有助于水分的扩散迁移;依次阶段降湿的干燥方式有助于提高山药片的干燥效率和品质,为山药热风干燥过程中如何调控相对湿度提供理论依据和技术支持。     

热湿交换器和加温湿化器对呼吸机相关性肺炎发生率影响的荟萃分析

目的 探讨热湿交换器(HME)与加温湿化器(HH)是否可降低机械通气患者呼吸机相关性肺炎(VAP)的发生。方法 通过计算机检索和手工检索PubMed、Cochrane数据库,收集1990年1月1日至2010年9月1日关于HME与HH对机械通气患者VAP影响的随机对照研究(RCT),按Cochrane协作网推荐的方法,对HME与HH预防机械通气患者VAP的发生率进行荟萃分析(Meta分析)。结果 共纳入11篇RCT文献,其中HME组1 121例,HH组1 101例,两组VAP发生率分别为14.2％(159/1 121)和15.9％(175/1 101),相对危险度(RR)=0.88,95％可信区间(95％CI)0.72～1.07,P=0.21,表明与HH相比,HME并不降低机械通气患者VAP的发生率。筛选机械通气时间＞7 d的RCT进行亚组分析,共纳入8篇文献,其中HME组834例,HH组859例,VAP发生率分别为15.2％(127/834)和17.5％(150/859),RR=0.84,95％CI0.58～1.23,P=0.37,表明在机械通气时间＞7d的患者中,HME同样不降低VAP的发生率。结论 HME并不降低机械通气患者VAP的发生率,即使在机械通气时间超过7d的患者也是如此。由于有关的RCT数量相对较少、质量较低（缺少盲法）,需要高质量的大规模RCT进一步证实。     

卵磷脂对皮肤稳态的实验研究

目的：研究卵磷脂对哺乳动物皮肤的稳态作用。方法：采用皮肤外敷试验,以家兔皮肤角质层细胞水分含量,过氧化脂质水平和角质细胞脂褐素含量为指标。结果：研究了卵磷脂对哺乳动物皮肤的稳态作用。结果表明：卵磷脂能明显提高皮肤角质层水分的含量,有效降低角质细胞脂质过氧化物（LPO）和脂褐素含量。结论：卵磷脂对皮肤具有保健作用。