Time Fractionation of Minor Lipids from Cold-Pressed Rapeseed Cake Using Supercritical CO<Subscript>2</Subscript>

This work explored the possibility of using supercritical carbon dioxide (SC-CO₂) to achieve fractionation of pre-pressed rapeseed (Brassica napus) cake oil at 30–50 MPa, at 40 or 80 °C, and increase the concentration of minor lipids (sterols, tocopherols, carotenoids) in the oil. Minor lipids are partially responsible for desirable antioxidant effects that protect against degradation and impart functional value to the oil. The weight and concentration of minor lipids in oil fractions collected during the first 60 min were analyzed. Cumulative oil yield increased with pressure, and with temperature at ≥40 MPa, but was lower at 80 °C than at 40 °C when working at pressure ≤35 MPa. Differences in solubility between the oil and minor lipids explained fractionation effects that were small for tocopherols. Unlike tocopherols, which are more soluble in SC-CO₂ than the oil, sterols and carotenoids are less soluble than the oil, and their concentration increased in the later stages of extraction, particularly at ≥40 MPa, when there was not enough oil to saturate the CO₂ phase. Because of the fractionating effects on rapeseed oil composition, there was an increase in the antioxidant activity of the oil in the second half as compared to the first half of the extraction. Consequently, this study suggests that SC-CO₂ extraction could be used to isolate vegetable oil fractions with increased functional value.     

Ethanol-Modified Supercritical Carbon Dioxide Extraction of the Bioactive Lipid Components of <Emphasis Type="Italic">Camelina sativa</Emphasis> Seed

Camelina sativa seed is an underutilized oil source that attracts a growing interest, but it requires more research on its composition and processing. Its high omega‐3 content and growing demand for clean food processing technologies make conventional oil extraction less attractive. In this study, the effect of extraction methods on the bioactive lipid composition of the camelina seed lipid was investigated, and its bioactive lipid composition was modified at the extraction stage using ethanol‐modified supercritical carbon dioxide (SC‐CO₂). Ethanol‐modified SC‐CO₂ extractions were carried out at varying temperatures (50 and 70 °C), pressures (35 and 45 MPa), and ethanol concentrations (0–10%, w/w), and were compared to SC‐CO₂, cold press, and hexane extraction. The highest total lipid yield (37.6%) was at 45 MPa/70 °C/10% (w/w) ethanol. Phospholipids and phenolic content increased significantly with ethanol‐modified SC‐CO₂ (p < 0.05). SC‐CO₂ with 10% (w/w) ethanol concentration selectively increased phosphatidylcholine (PC) content. Apparent solubility of camelina seed lipids in SC‐CO₂, determined using the Chrastil model, ranged from 0.0065 kg oil/kg CO₂ (35 MPa/50 °C) to 0.0133 kg oil/kg CO₂ (45 MPa/70 °C). Ethanol‐modified SC‐CO₂ extraction allowed modification of the lipid composition that was not possible with the conventional extraction methods. This is a promising green method for extraction and fractionation of camelina seed lipids to separate and enrich its bioactives.     

切题知识原则简论

本文第一部分简论知识的切题性及语境、总体性属性、多维度属性与复杂性等影响认知的因素;第二部分简论一般性智能及二十世纪高等教育中学科专业化对切题性知识的肢解;第三部分分析二十世纪(高等)教育中影响切题知识获取的三个基本问题:知识分割与封闭式专业化、还原与分离、虚假合理性。     

Degradation of atrazine using metalloporphyrins supported on TiO2 under visible light irradiation

A combined solar photo-Fenton and biological treatment is proposed for the decontamination of a mixture of five commercial pesticides commonly used in intensive agriculture Vydate (10% Oxamyl), Metomur (20% Methomyl), Couraze (20% Imidacloprid), Ditimur-40 (40% Dimethoate) and Scala (40% Pyrimethanil). Photo-Fenton experiments were conducted in a solar pilot reactor consisting of four compound parabolic collectors in which the pesticide mixture was treated at an original dissolved organic carbon (DOC) concentration of 200 mg/L in the presence of Fe²⁺ or Fe³⁺ concentration of 5, 20 and 55 mg/L. Ferrous ions were marginally more active than ferric in terms of active ingredient degradation, which followed zero order kinetics, more so in the early reaction stages. Photo-Fenton was also far more effective (by at least two orders of magnitude) than the respective dark reaction under identical experimental conditions.Irradiation for 50–100 min (normalized at 30 W/m² light intensity) at 20 mg/L Fe²⁺ was able to completely eliminate the active ingredients, and reduce DOC by about 15–50% and COD by 40–70%, respectively. At these conditions, ecotoxicity to the marine bacteria V. fischeri was substantially lessened, while aerobic biodegradability in tests with activated sludge was enhanced.     

Grafting polymerization of 2‐[3‐(2h‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate on vinyltriethoxysilane‐treated cotton for the preparation of ultraviolet‐protective fabrics

Vinyltriethoxysilane was used to modify the surface of cotton to provide polymerizable vinyl groups on the fiber surface. An ultraviolet‐absorbing monomer, 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate, was polymerized on the vinyltriethoxysilane‐treated fabric to prepare ultraviolet‐protective cotton. The effects of the amounts of the solvent, silane coupling agent, and 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate on the surface morphology and ultraviolet‐protection factor of the treated cotton fabric were investigated. With a suitable process, poly{2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate} was successfully coated onto the fabric, and it significantly reduced ultraviolet transmission through the fabric, resulting in a cotton fabric with excellent ultraviolet‐protection properties. The use of a silane coupling agent helped to ensure a polymer coating with good uniformity and good resistance to washing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Degradation of trichloroethene in water by electron supplementation

Trichloroethene (TCE) is a common and recalcitrant contaminant in groundwater. Microbially catalyzed reductive dechlorination is a dominant pathway for TCE degradation, in which substrates and electron donors are essential. In this study, extraneous electron supplementation was attempted to enhance reductive dechlorination of TCE and its derivatives. Reactors were established with groundwater containing TCE, and a 6-V battery was used to supply an average current of 29 μA of dc power to feed electrons to the microcosms. We measured 80–90% depletion of TCE within 70 d in reactors (both sterile and non-sterile) containing 300–400 μg TCE/l and from 97 to 98% depletion in microcosms containing 10 mg TCE/l. No intermediate products such as dichloroethylene or vinyl chloride were detected during this study. Results demonstrate that electron-supplemented degradation of TCE appears to be an abiotic process that is unassociated with microbial populations or indigenous redox conditions. No apparent accumulation of TCE daughter products were observed and overall efficiency of this electroremediation process was calculated to be 6.9 g TCE degraded/kW h. This efficiency would make electron supplementation an attractive alternative to the substrate-amended biological reductive dechlorination of TCE.     

TWO-SIDED DRYING OF COATINGS ON POROUS WEBS

A relatively simple spreadsheet-based model of the drying of coated webs has been extended to cover coatings on porous webs Two cases have been modeled. In one the coating is assumed to fully saturate the porous web, with the drying being completely symmetrical about the center plane except for differences in the air velocities and temperatures. The drying rate in the constant rate period is then increased, but because of the greater thickness that the coating now occupies, diffusion is much slower and the falling rate drying can be slower, even though it takes place on both sides. In the other case the coating is assumed to lie on top of the porous web, with solvent vapor diffusing through the web. Here the constant rate drying is only slightly faster than in the base case, but in the falling rate period the drying can be greatly accelerated Both models predict the temperatures and solvent levels throughout the length of the dryer.     

Surfactant-like Properties of Alkaline Extracts from Wastewater Biosolids

In order to assess the potential for utilizing wastewater biosolids as a source of useful substances, the surface activity of materials extracted from wastewater biosolids (activated sludge) by simple incubation with sodium hydroxide solutions at room temperature was assessed. The surface activity, measured by surface and interfacial tension methods, of the extracts was shown to be dependent on the extraction pH and the concentration of the organic matter solubilized in the alkaline solution. Increasing the extraction pH increased the surface activity of the extract (lower surface tensions), which is linked to the presence of more hydrophobic species in the extract. After adjusting the pH to more acidic values (e.g., pH = 4), the extracts retained their surface activity. The apparent CMC (critical micelle concentration) of pH 12.6 extracts was approximately 1,000 mg/L (based on total organic carbon or TOC), and the surface tension after CMC approximately 35 mN/m. While the CMC of the extract is significantly higher, when compared to a conventional surfactant, sodium dodecyl benzene sulfonate (SDBS, CMC ~ 25 mg/L), its surface tension at CMC was comparable. Above its CMC, the pH 12.6 extract had similar interfacial tensions than SDBS against toluene, heptane and hexadecane. Furthermore, the extract and SDBS had similar detergency performance for the removal of hexadecane from cotton. Skin corrosivity tests of the neutralized extracts show that they have comparable toxicity to conventional anionic surfactants such as sodium dodecyl sulfate. The potential use of these extracts in commercial products is discussed.     

Silicon Encapsulated Carbon Nanotubes

A dual stage process of depositing bamboo-like carbon nanotubes (BCNTs) by hot filament chemical vapor deposition (HFCVD) and coating Si using Radio frequency sputtering (RFS) technique. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron field emission studies (EFE). SEM results suggest a dense network of homogeneous silicon-coated BCNTs. From the comprehensive analysis of the results provided by these techniques emerges the picture of Si encapsulated BCNTs.