微藻基因工程在高价值化合物生产上的应用

微藻在生产蛋白质、油脂、色素等方面具有作为细胞工厂的潜力,在解决传统生物量生产和市场未来的一些局限性方面发挥着推进作用。基因工程促进了微藻的改良,推动了微藻的产业化进程。本文综述了近年来微藻基因工程的研究进展以及基因工程在微藻生产生物燃料、医药等方面的应用。本文能为基因工程技术在微藻中的研究及应用提供思路,从而使微藻以及微藻产品变得更具有经济竞争力。     

The Effect of Atmospheric Organic Compounds on the Fe-Catalyzed S(IV) Autoxidation in Aqueous Solution

Laboratory experiments were conducted with real atmospheric aerosol particles as well as with synthetic solutions under dark conditions, to simulate some of the chemical features of aerosols. In solutions obtained by the leaching of aerosols (size range >D _ae: 0.4–1.6 m) that contained sufficient amounts of transition metal ions (e.g. Fe) and organic species (e.g. oxalate), S(IV) oxidation rates were significantly lower than those expected from the Fe-catalyzed S(IV) autoxidation in Milli-Q water. The results suggest that oxalate is responsible for much of the observed inhibition. Acetate and formate also inhibit the reaction, but to a much lesser extent. Oxalate has a strong inhibiting effect on the Fe-catalyzed S(IV) autoxidation at all investigated pH values (2.8, 3.7 and 4.5). It was established that Fe(III)-oxalato complexes affect the redox cycling of Fe(II)/Fe(III) and that the observed decrease of the reaction rate is caused by the reduced amount of catalytically active Fe(III) due to the complexation with oxalate. For the system Fe-S(IV)-O₂-oxalate at initial pH 3.7 the reaction rate was calculated using exponential simplification to account for oxalate influence on the amount of free Fe(III) by the following equation:–r_S(IV) = k · [S(IV)] · [Fe(III))] · e ^-b·[Ox]     

运用原油吡咯类含氮化合物研究塔里木盆地塔中地区石油的二次运移

在塔里木盆地塔中地区的原油中分离和检测到咔唑类含氮化合物,并成功地将其应用于油气运移研究,烷基咔唑类化合物大量存在于所分析的样品中,苯并咔唑只在部分样品检测到且含量小,而二苯并卟唑则未发现,根据Ｃ２烷基咔唑的Ｇ１,Ｇ２和Ｇ３结构类型的分布,Ｃ３－咔唑／Ｃ２－咔唑比值以及烷基咔唑与苯并烷基咔唑的相对含量可知,塔中地区石炭系Ｃ３油组的石油分别从北西和南东两个方向向塔中４号构造的高点侧向运移,研究还表明     

TECHNICAL NOTE An experimental investigation of air flow patterns in saturated soils during air sparging

Air sparging is an emerging method used to remediate saturated soils and groundwater that have been contaminated with volatile organic compounds (VOCs). During air sparging, air is injected into the subsurface below the lowest known depth of contamination. Due to buoyancy, the injected air will rise through the zone of contamination. Through a variety of mechanisms, including volatilization and biodegradation, the air will serve to remove or help degrade the contaminants. The contaminant-laden air will continue to rise towards the ground surface, eventually reaching the vadose zone, where the vapours are collected and treated using a soil vapour extraction (SVE) system.Air sparging performance and ultimately contaminant removal efficiency is highly dependent on the pattern and type of subsurface air flow. This paper presents the results of a laboratory experimental study which investigated the injected air flow pattern development within an aquifer simulation apparatus. The test apparatus consisted of a tank measuring 61 cm long by 25.4 cm wide by 38.1 cm high. The apparatus was equipped with one air injection well and two vapour extracton wells. Three different soils were used to simulate different aquifer conditions, including a sand, a fine gravel and a medium gravel. Experiments were performed with different injected air pressures combined with different vacuum and groundwater flow conditions. Experiments were also conducted by injecting air into simulated shallow aquifers with different thicknesses. The air flow patterns observed were found to depend significantly on the soil type, groundwater flow conditions and system controls, including injected air pressure, flow rate and applied vacuum. © Rapid Science Ltd. 1998     

南极拉斯曼丘陵莫愁湖和团结湖水中有机物剖析(英)

Information on the organic compounds in water of Mochou Lake and Heart Lake, Antarctica is given in this paper. 93 organic compounds were identified from 121 chemical constituents in lake water, including n-alkanes, lipidal isopentadienes, aromatic hydrocarbons, polycyclic aromatics, alcohols, aldehydes, ketones, esters, monocarboxylic acids and phthalic esters in the range of 0. 027～4. 97 μg/L. Organic compounds of global occurrence like BHC, DDT and PCBs were detected in the water,at the concentration of 0. 012～0. 356 μg/L.     

Application of Non-Ionic Solid Sorbents (XAD Resins) for the Isolation and Fractionation of Water-Soluble Organic Compounds from Atmospheric Aerosols

A detailed procedure using non-ionic macropourous XAD-8 and XAD-4 resins is presented for the isolation and fractionation of aerosol water-soluble organic compounds (WSOC) from aerosol samples. The procedure entails adsorption of WSOC fraction onto XAD-8 and XAD-4 resins, desalting of the adsorbed organic material with ultra-pure water, elution of the retained organic matter with 40% MeOH solution and freeze-drying. Due to resin’s different properties and to certain hydrophobic/hydrophilic interactions between the resin polymers and the organic matter, two major fractions were obtained; namely the XAD-8 and the XAD-4 eluates. The XAD-8 eluate, which accounts for 55–60% of total aerosol WSOC, is represented by partially acidic compounds with significant hydrophobic moieties. The XAD-4 fraction holds few conjugated systems and a higher content of hydrophilic structures with low molecular size, and accounts for 9% of total WSOC. The isolated WSOC sub-fractions were nearly free from inorganic species, and successful recoveries of organic matter from the resins were accomplished. With this procedure the XAD-8 eluate yields a mixture representative of those WSOC that are highly conjugated compounds in atmospheric aerosols. It also allows a successful characterisation of the organic material by advanced analytical techniques without the interference of inorganic species present in the original sample of atmospheric particles.     

Gas Chromatographic Determination of Extractable Compounds Composition and Emission Rate of Volatile Terpenes from Larch Needle Litter

A combination of solid-phase microextraction (SPME) and gas chromatography can be successfully used both for establishing the qualitative composition of volatile organic compounds (VOC) emitted by leaf litter and for determining their emission rates. Taking as an example European larch litter, it is shown that dead plant material contains considerable amounts of volatile components as well as non-volatile compounds that can be VOC precursors formed as a result of enzymatic reactions. It is proposed to include the determination of extractable compounds into the methodology of studying litter as a source of atmospheric VOC. Some data on litter mass are reported and it is concluded that this data may be included into special models for emission evaluation. In this work the distribution coefficients of monoterpene hydrocarbons between the gas phase and polydimethylsiloxane fiber coating necessary for quantitative determinations in SPME were estimated.     

Measurements of Atmospheric Concentrations of Reduced Sulphur Compounds in the All Saints Bay Area in Bahia,Brazil

Atmospheric concentrations of several reduced sulphur compounds (H₂S, COS, CH₃SH, CH₃SCH₃, CS₂) originating from both natural and anthropogenic sources were measured at a number of locations in the All Saints Bay area and Reconcavo Baiano, Brazil.The volatile reduced sulphur compounds were collected by pre-concentration using cryo-tubes. Analysis of these compounds was carried out at a later date using gas chromatography with a flame photometric detector. In areas dominated by biogenic sources, the COS concentration varied between 0.5 and 1.0 ppbv, consistent with its normal global distribution in the atmosphere.Areas without direct industrial influence showed low atmospheric concentrations for all volatile sulphur compounds ( 0.25 ppb_v).The anthropogenic influence of the Petrochemical Complex in Camaçari resulted in relatively high levels of some reduced sulphur compounds, such as COS (8 ppb_v), CH₃SH (1.50 ppb_v), H₂S (1.35 ppb_v) and CS₂ (0.3 ppb_v). In mangrove areas, the H₂S concentrations (0.2 ppb_v) were almost twice as high as those in the air masses arriving from the Atlantic Ocean. The maximum H₂S concentrations were found in the industrial area of the Petrochemical Complex in Camaçari, but did not reach the limit of human perception (0.14 ppb_v) and rarely reached the typical recognizable smelling level (0.40 ppb_v). Industrial emissions from the Landulfo Alves Refinery increased the COS, DMS and CS₂ concentrations to 2.0, 0.55 and 0.2 ppb_v, respectively.     

Oxygen consumption in the shrimp,Palaemonetes pugio,exposed to fluctuating temperatures and food contaminated with the diaromatic petroleum hydrocarbon,dimethylnaphthalene

Oxygen consumption rates (V?o₂) in the grass shrimp Palaemonetes pugio were determined after a 32 day exposure to fluctuating temperatures (FT) (18–22°C) and/or dimethylnaphthalene (DMN)-contaminated food (0·24 μg DMN g wet wt^?1) and again after a 16 day recovery period of stable temperatures (20°C) and uncontaminated food. Ingestion of DMN-contaminated food for 32 days resulted in elevated V?>o₂ in shrimp exposed to declining oxygen concentrations. After the 32 day exposure period, FT had no significant effect on V?o₂ at 15, 20 and 25°C, tissue V?o₂ and V?o₂ in declining oxygen. Hemolymph copper concentrations were significantly depressed in shrimp exposed to DMN-contaminated food. After the 16 day recovery period, shrimp from the FT regime exhibited depressed V?o₂ when exposed to 25°C but not to 15°C. These depressed respiratory rates were offset by the stimulatory effect of DMN-contaminated food.These respiration studies were generally unproductive in explaining the previously reported effects of FT and DMN-contaminated food on the survival of P. pugio under hypoxic conditions.     

X-ray photoelectron study of oxygen bonding in crystalline C–S–H phases

We recorded the photoelectron spectra of various crystalline calcium silicate hydrates (C–S–Hs) and have examined their O 1 s photoelectron spectra. The spectra are asymmetric, with contributions assigned primarily to bridging and non-bridging oxygen species. There is an increased contribution due to the presence of non-bonding oxygen atoms with increasing calcium:silicon ratio. Additionally, there are slight changes in theO 1s-binding energies with changes in calcium:silicon ratio. These changes are explained in terms of bonding and silicate structure.