On-road and laboratory investigation of low-level PM emissions of a modern diesel particulate filter equipped diesel passenger car

Modern diesel particulate filter (DPF) systems are very effective in reducing particle emissions from diesel vehicles. In this work low-level particulate matter (PM) emissions from a DPF equipped EURO-4 diesel vehicle were studied in the emission test laboratory as well as during real-world chasing on a high-speed test track. Size and time resolved data obtained from an engine exhaust particle sizer (EEPS) and a condensation particle counter (CPC) are presented for both loaded and unloaded DPF condition. The corresponding time and size resolved emission factors were calculated for acceleration, deceleration, steady state driving and during DPF regeneration, and are compared with each other. In addition, the DPF efficiency of the tested vehicle was evaluated during the New European Driving Cycle (NEDC) by real time pre-/post-DPF measurements and was found to be 99.5% with respect to PM number concentration and 99.3% for PM mass, respectively. PM concentrations, which were measured at a distance of about 10 m behind the test car, ranged from 1 to 1.5 times background level when the vehicle was driven on the test track under normal acceleration conditions or at constant speeds below 100 kmh^?1. Only during higher speeds and full load accelerations concentrations above 3 times background level could be observed. The corresponding tests in the emission laboratory confirmed these results. During DPF regeneration the total PM number emission of nucleation mode particles was 3–4 orders of magnitude higher compared to those emitted at the same speed without regeneration, while the level of the accumulation mode particles remained about the same. The majority of the particles emitted during DPF regeneration was found to be volatile, and is suggested to originate from accumulated sulfur compounds.     

Bestimmung von Mineralölkohlenwasserstoffen in Bodenproben mit Hilfe der Dünnschichtchromatographie

A thin-layer chromatographic method for the determination of mineral oil hydrocarbons (aliphatic compounds and naphtenes) of medium and low volatility in soil samples is presented which is based on their separation and quantitative determination. The extraction of the soil samples is effected by means of an n-hexane-acetone mixture (10∶1) supported by ultrasonics. The evaluation can be made visually or densitometrically by means of a thin-layer scanner. The applicability and restrictions of the method are shown. The advantage of the method lies in its low requirements pertaining to apparatus and chemicals, as well as in its rapidness which makes it suitable for quick in-situ analyses as, for example, for the assessment of the mineral oil content of a contaminated site.     

Phthalatkonzentrationen in Böden naturnaher Standorte des Sollings (Niedersachsen)

The phthalat concentrations in soil samples from the Solling (Ecological Research Project Solling) were measured. The samples were collected from a beech and a spruce forest and aTrisetum flavescens meadow. The distance from the tree trunks and the different horizons were taken into consideration as well. Dimethylphthalat, diethylphthalat, dibutylphthalat, butylbenzylphthalat, di-(2-ethylhexyl) phthalat and dioctylphthalat were determinated using GC/MS. From the six phthalates investigated, four were detected in the samples. Dimethyl and diethylphthalat were found at very low concentrations in only one sample. Dibutyl- and di-(2-ethylhexyl)phthalat were detected in eight of 21 samples. No phthalates were found in the samples from theTrisetum flavescens meadow. Two of the nine samples from the beech forest showed phthalates. In six of the nine samples from the spruce forest phthalates were detected. Phthalate concentrations in the spruce forest were always higher than those found in the beech forest.     

Improved degradation of azo dyes by lignin peroxidase following mutagenesis at two sites near the catalytic pocket and the application of peroxidase-coated yeast cell walls

• Mutations in Lignin peroxidase Trp171 environment improved azo dyes degradation. • Expression on yeast cell surface and cell lysis allowed reusability of biocatalyst. • Aga2-LiP chimeric variants were characterized. The enzymatic degradation of azo dyes is a promising alternative to ineffective chemical and physical remediation methods. Lignin peroxidase (LiP) from Phanerochaete chrysosporium is a heme-containing lignin-degrading oxidoreductase that catalyzes the peroxide-dependent oxidation of diverse molecules, including industrial dyes. This enzyme is therefore ideal as a starting point for protein engineering. Accordingly, we subjected two positions (165 and 264) in the environment of the catalytic Trp171 residue to saturation mutagenesis, and the resulting library of 10⁴ independent clones was expressed on the surface of yeast cells. This yeast display library was used for the selection of variants with the ability to break down structurally-distinct azo dyes more efficiently. We identified mutants with up to 10-fold greater affinity than wild-type LiP for three diverse azo dyes (Evans blue, amido black 10B and Guinea green) and up to 13-fold higher catalytic activity. Additionally, cell wall fragments displaying mutant LiP enzymes were prepared by toluene-induced cell lysis, achieving significant increases in both enzyme activity and stability compared to a whole-cell biocatalyst. LiP-coated cell wall fragments retained their initial dye degradation activity after 10 reaction cycles each lasting 8 h. The best-performing mutants removed up to 2.5-fold more of each dye than the wild-type LiP in multiple reaction cycles.     

Use of metal-reducing bacteria for bioremediation of soil contaminated with mixed organic and inorganic pollutants

Mixed contamination by organic and inorganic compounds in soil is a serious problem for remediation. Most laboratory studies and field-scale trials focused on individual contaminant in the past. For concurrent bioremediation by biodegradation and bioleaching processes, we tested metal-reducing microorganism, Geobacter metallireducens. In order to prove the feasibility of the coupled process, multiple-contaminated soil was prepared. Mineralogical analyses have shown the existence of labile forms of As(V) as amorphous and/or weakly sorbed phases in the secondary Fe oxides. In the biotic experiment using G. metallireducens, biodegradation of toluene and bioleaching of As by bacteria were observed simultaneously. Bacteria accelerated the degradation rate of toluene with reductive dissolution of Fe and co-dissolution of As. Although there have been many studies showing each individual process, we have shown here that the idea of concurrent microbial reaction is feasible. However, for the practical use as a remediation technology, more details and multilateral evaluations are required in future studies.     

干旱胁迫下5种三叶草的生理反应(英文)

为了解三叶草属抗旱的生理机理,寻找适宜干旱地区种植的三叶草品种,比较了地三叶草(Trifoliumsubterraneum L.)、大花三叶草(T.michelianum Savi)、白三叶草(T.repens L.)、高加索三叶草(T.ambiguum M.Bieb.)和草莓三叶草(T.fragiferum L.)在人工干旱条件下4 wk的生长和生理反应.结果表明,干旱处理下大花三叶草、草莓三叶草和白三叶草地上部分干重严重减少,分别降低了70%、66%和64%,而高加索三叶草和地三叶草减少不到50%;高加索三叶草叶片水势降低到-2.0 MPa以下,而其他4种三叶草只降低到-1.5MPa左右;高加索三叶草和草莓三叶草叶片光合速率降低25%,而地三叶草、白三叶草和大花三叶草下降35%~63%.此外,干旱条件下,5种供试三叶草叶片中游离脯氨酸含量普遍增加,其中高加索三叶草和白三叶草分别增加到2.5倍和3.1倍.研究显示高加索三叶草在多项重要生长和生理指标中表现出很强的抗旱性,因此认为其可作为干旱地区栽培白叶草的补充或替代种.图1表3参22     

Stability and self-organization of proteins

X-ray crystallography and NMR provide insight into the three-dimensional structure of proteins at high resolution yielding a relatively small number of stable "topologies". Their free energies of stabilization are minute compared to the total molecular energy. Molecular adaptation to extremes of physical conditions at the protein level refers to marginal alterations of the intramolecular interactions; clearcut predictions with respect to the correlation of protein structure and protein stability are at present not possible. The acquisition of the native structure of proteins is determined by the kinetically accessible minimum of potential energy. The overall mechanism may be described as a hierarchical condensation with elements of secondary/super-secondary structure and subdomains/domains as intermediate stages. In the case of oligomeric and multimeric proteins, folding and association of subunits follow a consecutive uni-bimolecular mechanism, the kinetics of which can be simulated with high precision. The "code of protein folding" is still unknown.     

Die Technik der Nukleinsäurehybridisierung und ihre Bedeutung für diagnostische Fragestellungen

Nucleic acid hybridization techniques (e.g., Southern blotting and in situ hybridization) gain increasing importance in laboratory medicine, as demonstrated by examples in this paper. The molecular basis of this approach to detect nucleic acids homologous to known DNA probes is explained. It is concluded that this technique has advantages in the detection of pathogens compared to other methods used in laboratory medicine.