原油乳状液稳定性研究Ⅲ北海原油界面活性组分特性

研究了北海原油界面活性组分在空气中的氧化，红外、紫外光谱，及作为乳化剂对模型乳状液稳定性的影响。研究结果表明，所有胶质、沥青质组分均含有界面活性物质，其中含较多芳香羰基、芳香碳碳双键的化合物对增加油水乳状液的稳定性有重要作用。界面活性组分氧化后羰基浓度增加，作为乳化剂形成的油水乳状液稳定性增大。与胶质相比，沥青质含芳香羰基和芳香碳碳双键较多，分子量较大，在油水界面形成的膜强度较高，所形成的乳状液稳定性也较大。     

Distribution of Free and Esterified Oxylipins in Cream,Cell, and Skim Fractions of Human Milk

Human milk contains oxylipins involved in infant development. Although oxylipins have been identified in whole or skim milk, their localization within human milk cream, cell, and skim fractions is not known. This study determined the distribution of free and esterified oxylipins in cream, cell, and skim fractions of human milk. Out of 72 oxylipins probed by mass-spectrometry, 42, 29, and 41 oxylipins (free or bound) were detected in cream, cell, and skim fractions, respectively. Over 90% of free and bound oxylipins were derived from linoleic acid in all milk fractions. Other oxylipins were derived from n-6 arachidonic acid and dihomo-gamma-linolenic acid, and n-3 alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Free oxylipins were more abundant in skim milk (59.9% of total oxylipins) compared to cream and cell pellet, whereas esterified oxylipins were most abundant in milk cream and cell pellets (74.9–76.9%). The heterogenous distribution of oxylipins in different fractions of human milk may regulate the guided release of these bioactive signaling molecules within infants.     

Methane yield of oat husks

The biogas yield of solid manure from dairy cattle depends on its quality and the proportion of excreta and organic litter material contained within. The biogas yield of both faeces and straw is available in literature. Straw is a common litter material of mixed farms. However, straw is scarcely available on dairy farms. Oat husks are appropriate to replace or supplement straw for use as litter material. In this study, the actual methane yield and the total methane potential of oat husks were determined. Based on an optimized test with ground oat husks, the total methane potential resulted from regression and extrapolation of the experimental data. The total methane potential was determined with 242 L_N CH₄ kg⁻¹ VS added. Additionally, the actual methane yield over retention time at a digestion temperature of 37 °C was determined, using untreated oat husks. For 42 days of retention, the methane yield was 202 L_N CH₄ kg⁻¹ VS added at 52% CH₄ content. Results indicate that the methane yield of oat husks reaches the same level as that of straw. The total methane potential is not higher, but digestion of oat husks may proceed faster. Verification of the laboratory results on-farm revealed that the contribution of oat husks to overall methane production of a prototype biogas plant for solid manure might reach up to 80%.     

地表气压对温室气体柱总量反演的敏感性分析及敦煌地区温室气体的柱总量观测

地表气压对温室气体浓度反演具有非常重要的影响。利用地基便携式傅里叶变换光谱仪EM27/SUN观测了敦煌地区H2O,CO2,CH4及CO气体分子的浓度,获得了2018年6月27日到7月21日敦煌地区大气中XH2O,XCO2,XCH4及XCO的时间序列,结合敦煌观测数据,定量分析了地表气压对气体柱-平均摩尔分数Xgas(column-averaged dry air mole fractions, DMFs)反演的影响。结果表明:XH2O,XCO2,XCH4及XCO与地表气压密切相关,相关系数均高于0.99,柱总量随地表气压的变化快慢决定柱-平均摩尔分数随地表气压的变化趋势。相比较CO2,CH4及CO分子,XH2O对地表气压的敏感性较弱,地表气压改变1 hPa,XH2O,XCO2,XCH4及XCO分别变化0.027 8%,0.065 9%,0.068 6%和0.062%;观测期间,H2O,CO2的浓度变化幅度波动较大,XCH4,XCO变化较小,XH2O平均值在2 000×10-6~6 000×10-6变化,而XCO2平均值在407.27×10-6~417.60×10-6变化,敦煌站点XH2O,XCO2,XCH4及XCO的测量精度分别为2.3%,0.14%,0.12%及1.7%,XCO2及XCH4的测量精度均优于TCCON网的测量精度;与GOSAT卫星数据对比结果显示,地基反演的XCO2,XCH4值均偏大,XCO2的绝对偏差为7.07×10-6,XCH4的绝对偏差为0.025×10-6;与WACCM数据对比显示,地基反演XCO2结果多数大于WACCM值,最大绝对偏差可以达到8.0×10-6,地基反演XCH4值小于WACCM值,最大绝对偏差为0.032×10-6。实时观测数据更能反映当地的具体情况,研究结果可为我国温暖带干旱性气候温室气体源与汇的研究提供数据支撑和理论基础。     

A STUDY OF MULTI-FUNCTIONAL ELECTROLYTIC OLIGOMERS AS DISPERSANTS FOR CONCENTRATED AQUEOUS ALUMINA SUSPENSIONS

ABSTRACT

The effects of dispersant charge density, active binding site density, and hydrophilic/hydrophobic balance on the rheology of concentrated aqueous alumina suspensions have been studied. Twenty-one three- and four-component oligomeric dispersants with varying monomer composition were synthesized by free-radical telomerization of acrylic acid (AA), acrylamide (AAm), methyl acrylate (MA), and sodium acrylamido-2-methyl-propanesulfonate (NaAMPS). The monomer compositions for the dispersants were varied between 40 and 75%, 3 and 50%, 3 and 30%, and 0 and 15% for AA, AAm, MA, and NaAMPS, respectively. Aqueous alumina suspensions of volume fraction 0.50 at pH 9.5 were obtainable with all the dispersants. Rheological measurements of these suspensions revealed that most of these dispersants produced suspensions with similar viscosity with only a few exceptions. Rheological comparison of these suspensions with suspensions produced with poly(acrylic acid) of molecular weight 1800 (PAA-1800) showed that a good number of the multi-component were more effective than the PAA-1800, This material is recognized as being one of the most effective dispersants for alumina suspensions under conditions used in this study, according to the unpublished ERC results. Zeta-potential measurements and adsorption studies gave a good indication that differences between PAA-1800 and the multi-component dispersants may be due to steric forces brought about by differences in dispersant conformation and adsorption behavior.     

Antioxidant activity of the fractions separated from the unsaponifiable matter of bene hull oil

The unsaponifiable matter (USM) of bene hull oil were separated into hydrocarbons (7.3%), carotenes (7.1%), tocols (48.4%), linear and triterpenic alcohols (1.7%), methyl sterols (11.2%), sterols (6.2%), and triterpenic dialcohols (18.0%). Regardless hydrocarbons fraction, the whole USM and all fractions had the EC₅₀ (mg/ml) value significantly lower than (USM, 0.99; tocols, 1.05; carotenes, 3.93; triterpenoids, 1.74–9.89) that of α-tocopherol (36.7). α-Tocopherol, the whole USM, and all fractions were able to increase significantly the stability of sunflower oil at 50 °C, so that the highest stabilizing effect belonged to the USM fractions with no significant differences amongst them, followed by the whole USM and α-tocopherol. The sunflower oil had an OSI (oil/oxidative stability index) of 3.54 h, which was considerably promoted by some of components (tocols, 4.35; hydrocarbons, 4.43 h; USM, 4.5 h; triterpenic alcohols, 5.1 h; carotenes, 5.49 h). The FRAP and DPPH tests showed nearly similar results.     

Mapping northern land cover fractions using Landsat ETM+

The goal of fractional mapping is to obtain land cover fraction estimates within each pixel over a region. Using field, Ikonos and Landsat data at three sites in northern Canada, we evaluate a physical unmixing method against two modeling approaches to map five land cover fractions that include bare, grass, deciduous shrub, conifer, and water along an 1100 km north-south transect crossing the tree-line of northern Canada. Error analyses are presented to assess factors that affect fractional mapping results, including modeling method (linear least squares inversion (LLSI) vs. linear regression vs. regression trees), number of Landsat spectral bands (3 vs. 5), local and distant fraction estimation using locally and globally calibrated models, and spatial resolution (30 m vs. 90 m). The ultimate purpose of this study is to determine if reliable land cover fractions can be obtained for biophysical modeling over northern Canada from a three band, resampled 90 m Landsat ETM+ mosaic north of the tree-line. Of the three modeling methods tested, linear regression and regression trees with five spectral bands produced the best local fraction estimates, while LLSI produced comparable results when unmixing was sufficiently determined. However, distant fraction estimation using both locally and globally calibrated models was most accurate using the three spectral bands available in the Landsat mosaic of northern Canada at 30 m resolution, and only slightly worse at 90 m resolution. While local calibrations produced more accurate fractions than global calibrations, application of local calibration models requires stratification of areas where local endmembers and models are representative. In the absence of such information, globally calibrated linear regression and regression trees to estimate separate fractions is an acceptable alternative, producing similar root mean square error, and an average absolute bias of less than 2%.     

Pyrolysis characteristics of bio-oil fractions separated by molecular distillation

Molecular distillation was used to separate bio-oil into a light fraction, a middle fraction and a heavy fraction. The chemical composition of the three fractions and the crude bio-oil was analyzed by gas chromatography coupled with mass spectrometry (GC–MS). The diversity of the components reflected the complexity of the bio-oil and the necessity for fractionation. The pyrolysis characteristics of the bio-oil fractions were determined with a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG–FTIR). The weight loss of components was in agreement with the chemical composition. The light fraction evaporated fastest with the formation of water, CO₂, hydrocarbons and alcohols. The heavy fraction had the slowest rate of decomposition and the highest char residue yield due to the presence of phenols and saccharides, and the pyrolysis products included CO₂ and alcohols or phenols, which was similar to the middle fraction except the formation of water and formic acid. The release of CO or methane, evidence of a secondary reaction, began at ∼450 °C in the pyrolysis of the light and middle fractions.     

Development of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) on sorghum milling fractions

A series of tests was conducted to determine if Tribolium castaneum (Herbst), the red flour beetle, could survive on six milled sorghum fractions: Bran, Coarse Grits, Fine Grits, Flour, Red Dogs, and Shorts. In the first test, parental adults were exposed on the fractions, removed, and then the fractions were held for six-seven weeks at 27 °C. Late instar larvae and progeny adults were present in all fractions. In the second test, at least 80% of single neonates (1-2-day-old larvae) held on 1 g of a fraction at 27 °C for seven weeks were able to complete development to the adult stage. In the final test, individual neonates were held on 1 g of a fraction at 37 °C, 32 °C, 27 °C, or 22 °C. Time to adult emergence at each temperature ranged from 17 to 23 days, 21–27 days, 28–50 days, and 67–113 days, respectively, depending on the specific fraction. Logistic functions were compared for mean developmental times for each temperature-fraction combination. The six fractions were also analyzed for ash, fat, fiber, moisture, protein, and starch content. The fractions varied with respect to these chemical constituents; fat and moisture content were negatively correlated with development in some comparisons, though overall there was no correlation between these chemical components and neonate development on the fractions. Temperature had an obvious effect on neonate development, which has implications for assessing risk of pest infestations inside sorghum mills during warmer months of the calendar year. In addition, T. castaneum will reproduce and develop on all of the sorghum fractions included in this study, which are commonly generated during the sorghum milling process. Sanitation and removal of residual materials such as the measured fractions could also help with overall pest management of T. castaneum.