Distribution profiles of endocrine disrupting PAHs/APEOs in river sediments: is there a potential ecotoxicological problem?

The endocrinic/mutagenic potencies of the endocrine disrupting chemicals (EDCs) polycyclic aromatic hydrocarbons (PAHs), alkylphyenol ethoxylates (APEOs) and their metabolites are well documented. Less so is the endocrinic ecotoxicological/health risk potential of these persistent organic pollutants (POPs) in river sediments. From approximately 5 x 10(8) m3/y of sewage produced in Israel, approximately 70% are reused, mainly in agriculture, following a conventional activated sludge treatment (AST). A major related question is: does this practice conform to sustainability? We have found the APEOs concentration profiles of Israel's rivers/streams, Mediterranean Sea coastal water and groundwater, to be 12.5-74.6, 4.5-25.0 and trace-20.2 microg/L, respectively. In two "representative" rivers, in the central coastal region of the country, the total concentrations of the PAHs and APEOs were found to be (in the upper layers of their sediments) 1.02-1.59, 1.78-2.30, 1.48-3.12 and 31.27-376.23, 2.40-91.70, 62.99-63.63 microg/g, respectively. The distribution of the PAHs in the co-presence of APEOs in rivers and their sediments, can be rationalized in terms of the hydrophobicity/nonbiodegradability of the former and the hydrophilicity-CMC/nonbiodegradability of the latter. Based on (a) the zebrafish egg production test (ZFEPT) - a long-term exposure of zebrafish to actually found environmental concentrations of EDCs; and (b) the low effectiveness of POPs removal in AST, our preliminary conclusions are that (1) there is a potential ecotoxicological/health risk problem; and (2) the practice of conventional wastewater treatment plants (WWTPs)-treated water reuse is incompatible with sustainability.     

Determination of band offsets in heterostructured colloidal nanorods using scanning tunneling spectroscopy

The ability to tailor the properties of semiconductor nanocrystals through creating core/shell heterostructures is the cornerstone for their diverse application in nanotechnology. The band-offsets between the heterostructure components are determining parameters for their optoelectronic properties, dictating for example the degree of charge-carrier separation and localization. So far, however, no method was reported for direct measurement of these factors in colloidal nanocrystals and only indirect information could be derived from optical measurements. Here we demonstrate that scanning tunneling spectroscopy along with theoretical modeling can be used to determine band-offsets in such nanostructures. Applying this approach to CdSe/CdS quantum-dot/nanorod core/shell nanocrystals portrays its type I band structure where both the hole and electron ground state are localized in the CdSe core, in contrast to previous reports which predicted electron delocalization. The generality of the approach is further demonstrated in ZnSe/CdS nanocrystals where their type II band alignment, leading to electron-hole separation, is manifested.     

A two-state electronic antigen and an antibody selected to discriminate between these states

Inspired by biology where pathways are triggered and suppressed by specific binding of two molecules, we realize a functional interface between electronics and biology by replacing one of the pair molecules with a two-state "electronic antigen" device comprising a hydroquinone monolayer assembled on gold, and choosing for the pair molecule an antibody that discriminates between the two electrically selected redox states of the monolayer. Application of an oxidative +0.6 V pulse to the antigen switches it to its benzoquinone state where antibodies bind the layer. A subsequent -0.6 V pulse reduces the monolayer back to the unbinding hydroquinone state, releases the specifically bound antibody molecules, and prevents further binding.     

Measurement of wavelengths with phosphor storage image plates on a grazing incidence spectrograph

We recorded the spectra emitted by a Ne/Mg Penning discharge and by sliding spark discharges of Y and Mo in the 150-450 A range with phosphor storage image plates on a 10.7 m grazing incidence spectrograph. To obtain better conformance of the image plates to the focal surface of the concave grating, the plates were mounted on the curved surface with a backing of flexible steel plates. The exposed plates were read by a rotary drum scanner. With these techniques we achieved a wavelength accuracy of approximately 0.003 A. This is comparable to what is normally obtained with photographic plates on this instrument.     

Conservation practices in US agriculture and their implication for global climate change

Increase in the use of conservation practices by agriculture in the United States will enhance soil organic carbon and potentially increase carbon sequestration. This, in turn, will decrease the net emission of carbon dioxide. A number of studies exist that calibrate the contribution of various individual, site-specific conservation practices on changes in soil organic carbon. There is a general absence, however, of a comprehensive effort to measure objectively the contribution of these practices including conservation tillage, the Conservation Reserve Program and conservation buffer strips to an change in soil organic carbon. This paper fills that void. After recounting the evolution of the use of the various conservation practices, it is estimated that organic carbon in the soil in 1998 in the United States attributable to these practices was approximately 12,200,000 metric tons. By 2008, there will be an increase of approximately 25%. Given that there is a significant potential for conservation practices to lead to an increase in carbon sequestration, there are a number of policy options that can be pursued. These include education and technical assistance, financial assistance, research and development, land retirement and regulation and taxes.     

A Novel Rodent Model of Hypertensive Cerebral Small Vessel Disease with White Matter Hyperintensities and Peripheral Oxidative Stress

Cerebral small vessel disease (CSVD) is the second most common cause of stroke and a major contributor to dementia. Manifestations of CSVD include cerebral microbleeds, intracerebral hemorrhages (ICH), lacunar infarcts, white matter hyperintensities (WMH) and enlarged perivascular spaces. Chronic hypertensive models have been found to reproduce most key features of the disease. Nevertheless, no animal models have been identified to reflect all different aspects of the human disease. Here, we described a novel model for CSVD using salt-sensitive ‘Sabra’ hypertension-prone rats (SBH/y), which display chronic hypertension and enhanced peripheral oxidative stress. SBH/y rats were either administered deoxycorticosteroid acetate (DOCA) (referred to as SBH/y-DOCA rats) or sham-operated and provided with 1% NaCl in drinking water. Rats underwent neurological assessment and behavioral testing, followed by ex vivo MRI and biochemical and histological analyses. SBH/y-DOCA rats show a neurological decline and cognitive impairment and present multiple cerebrovascular pathologies associated with CSVD, such as ICH, lacunes, enlarged perivascular spaces, blood vessel stenosis, BBB permeability and inflammation. Remarkably, SBH/y-DOCA rats show severe white matter pathology as well as WMH, which are rarely reported in commonly used models. Our model may serve as a novel platform for further understanding the mechanisms underlying CSVD and for testing novel therapeutics.     

Model-free dynamic contrast-enhanced MRI analysis: differentiation between active tumor and necrotic tissue in patients with glioblastoma

Magnetic Resonance Materials in Physics, Biology and Medicine - Treatment response assessment in patients with high-grade gliomas (HGG) is heavily dependent on changes in lesion size on MRI....