Competitive degradation and detoxification of carbamate insecticides by membrane anodic Fenton treatment

The competitive degradation of six carbamate insecticides by membrane anodic Fenton treatment (AFT), a new Fenton treatment technology, was carried out in this study. The carbamates studied were dioxacarb, carbaryl, fenobucarb, promecarb, bendiocarb, and carbofuran. The results indicate that AFT can effectively degrade these insecticides in both single component and multicomponent systems. The carbamates compete for hydroxyl radicals, and their kinetics obey the previously developed AFT kinetic model quite well. Hydroxyl radical reaction rate constants were obtained, and they decrease in the following order: dioxacarb approximately carbaryl > fenobucarb > promecarb > bendiocarb > carbofuran. The AFT is shown to have higher treatment efficiency at higher temperature. Degradation products of the carbamates were determined by gas chromatography/mass spectrometry, and it appears that degradation can be initiated by hydroxyl radical attack at different sites in the molecule, depending on the individual structure of the compound. Substituted phenols are the commonly seen degradation products. The AFT treatment can efficiently remove the chemical oxygen demand of the carbamate mixture, significantly increasing the biodegradability. Earthworm studies show that the AFT is also an effective detoxification process.     

Regulation of enzymes involved in the sulphur-assimilatory pathway

The regulation of enzymes involved in sulphate assimilation in plants has been investigated. Extractable activity of ATP sulphurylase (the first enzyme of the assimilatory pathway) has been shown to be regulated by sulphate availability and O-acctylserine (OAS) supply. OAS addition to the medium increased extractable activity and was able, at least partially, to overcome the repression of extraclable activity observed by supply of sulphate and cysteine. Cysteine synthase, the final enzyme of the cysteine biosynthetic pathway, was not regulated under these conditions.     

An update of the mercury inventory and atmospheric mercury fluxes to and from Finland

Finland, the northern-most agricultural/industrial country in the world, has been for some time steadily improving environmental mercury (Hg) research. This paper focuses upon Hg recovery during zinc production, uses of Hg, updating of information on Hg emissions and atmospheric transport of Hg to and from Finland. The recovery of Hg as a by-product of zinc production began in 1970. The highest amount of recovered Hg was noted to be 160 t in 1989. Total uses of Hg in different sectors were about 7.4 t in 1992, which had decreased by 50% since the year 1987. In 1992, the estimated Hg emission to air was 2 t yr^?1, whereas to water and land the emission was about 0.20 and 3.67 t yr^?1, respectively. Natural Hg emission in Finland was estimated to be about 0.4 t yr^?1 (range: 0.3 to 0.5 t yr^?1). In addition, an initial attempt was made to estimate the atmospheric Hg flux to and from Finland; these values were noted to be 2.7 and 2.1 t yr^?1, respectively.     

Plant pathogens in recycled irrigation water in commercial plant nurseries and greenhouses: their detection and management

With water conservation and reuse a priority for communities worldwide, recycling irrigation water in commercial plant nurseries and greenhouses is a logical measure. Plant pathogenic microorganisms may be present in the initial water source, or may accrue and disperse from various points throughout the irrigation system, constituting a risk of disease to irrigated plants. The continual recycling of this water is exacerbating this plant disease risk. Accurate and timely detection of plant pathogenic propagules in recycled irrigation water is required to assess disease risk. Both biological and economic thresholds must be established for important plant-pathosystems. Plant pathogens in recycled irrigation water can be managed by a variety of treatment methods that can be arranged in four broad categories: cultural, physical, chemical, and biological. An integrated approach using one or more techniques from each category is likely to be the most effective strategy in combating plant pathogens in recycled irrigation water.     

Generation of a large combinatorial library of the immunoglobulin repertoire in phage lambda

A novel bacteriophage lambda vector system was used to express in Escherichia coli a combinatorial library of Fab fragments of the mouse antibody repertoire. The system allows rapid and easy identification of monoclonal Fab fragments in a form suitable for genetic manipulation. It was possible to generate, in 2 weeks, large numbers of monoclonal Fab fragments against a transition state analog hapten. The methods described may supersede present-day hybridoma technology and facilitate the production of catalytic and other antibodies.     

Dynamic pore-pressure fluctuations in rapidly shearing granular materials

Results from two types of experiments show that intergranular pore pressures fluctuated dynamically during rapid, steady shear deformation of water-saturated granular materials. During some fluctuations, the pore water locally supported all normal and shear stresses, while grain-contact stresses transiently fell to zero. Fluctuations also propagated outward from the shear zone; this process modifies grain-contact stresses in adjacent areas and potentially instigates shear-zone growth.     

Initiating and cancer-propagating cells in TEL-AML1-associated childhood leukemia

Understanding cancer pathogenesis requires knowledge of not only the specific contributory genetic mutations but also the cellular framework in which they arise and function. Here we explore the clonal evolution of a form of childhood precursor-B cell acute lymphoblastic leukemia that is characterized by a chromosomal translocation generating a TEL-AML1 fusion gene. We identify a cell compartment in leukemic children that can propagate leukemia when transplanted in mice. By studying a monochorionic twin pair, one preleukemic and one with frank leukemia, we establish the lineal relationship between these "cancer-propagating" cells and the preleukemic cell in which the TEL-AML1 fusion first arises or has functional impact. Analysis of TEL-AML1-transduced cord blood cells suggests that TEL-AML1 functions as a first-hit mutation by endowing this preleukemic cell with altered self-renewal and survival properties.     

Effects of basal debris on glacier flow

Glacier movement is resisted partially by debris, either within glaciers or under glaciers in water-saturated layers. In experiments beneath a thick, sliding glacier, ice containing 2 to 11% debris exerted shear traction of 60 to 200 kilopascals on a smooth rock bed, comparable to the total shear traction beneath glaciers and contrary to the usual assumption that debris-bed friction is negligible. Imposed pore-water pressure that was 60 to 100% of the normal stress in a subglacial debris layer reduced shear traction on the debris sufficiently to halt its deformation and cause slip of ice over the debris. Slip resistance was thus less than debris shearing resistance.