Reduced inorganic sulfur speciation in drain sediments from acid sulfate soil landscapes

We examined processes regulating reduced inorganic sulfur (RIS) speciation in drain sediments from coastal acid sulfate soil (ASS) landscapes. Pore water sulfide was undetectable or present at low levels (0.6-18.8 microM), consistent with FeS(s) precipitation in the presence of high concentrations of Fe2+ (generally >2 mM). Acid-volatile sulfide (AVS), with concentrations up to 1019 micromol g(-1), comprised a major proportion of RIS. The AVS to pyrite-S ratios were up to 2.6 in sediment profiles containing abundant reactive Fe (up to approximately 4000 micromol g(-1)). Such high AVS:pyrite-S ratios are indicative of inefficient conversion of FeS(s) to pyrite. This may be due to low pore water sulfide levels causing slow rates of pyrite formation via the polysulfide and H2S oxidation pathways. Overall, RIS speciation in ASS-associated drain sediments is unique and is largely regulated by abundant reactive Fe.     

The potential energy of a superconducting ring system locking magnetic flows in a gravity field

The possibility of creating a magnetic system of a plasma trap with levitating magnetic coils is under consideration. For this purpose, the analytical function of the potential energy of the system of several superconducting rings, which lock the required flows (at that, the one ring is fixed), versus the coordinates of free rings in the homogeneous gravity field under approximation of thin rings. Using calculations in the Mathcad medium, it is shown that, under definite values of parameters, there are equilibrium states of such a system. In the positions that corresponded to the calculated values, stable levitation states of the superconducting ring are observed experimentally in the field of another superconducting ring. The obtained results prove that a magnetic system can be created on the basis of a levitating quadrupole.     

Morphological and phase dependence of nanotitania materials generated under extreme pH conditions for large scale production of TiO<Subscript>2</Subscript> nanowires (basic) and nanosquares or nanrods (acidic)

The effect that the phase of the starting nanoseed titania (TiO₂), the pH of the solvent solution, and the processing methodology employed have on the properties of the resultant TiO₂ nanomaterials were explored. This led to the development of a new process to produce large-scale, phase pure, thin nanowires of TiO₂ at high pH and nanosquares at low pH. Anatase, rutile, and Degussa P25^TM TiO₂ nanoparticle starting materials (or nanoseeds) were processed in strongly basic (10 M KOH) and strongly acidic (conc. HX, where X = Cl, Br, I) solutions using solvothermal (SOLVO) and solution precipitation (SPPT) methodologies. Under basic SOLVO conditions, the nanoseeds were converted to H₂Ti₂O₅·H₂O nanowires. The SPPT basic conditions also produced the same phased nanowires for the rutile and anatase nanoseeds, while the Degussa nanomaterial yielded mixed phased [anatase:rutile (9:1)] nanowires. The SPPT method was found to produce substantially thinner nanowires in comparison to the SOLVO route, with comparable surface areas but the strong basic media led to etching of the glassware yielding HK₃Ti₄O₄(SiO₄)₃·4H₂O nanorods. Hybridization of these two processing routes led to the use of Nalgene^TM bottle as the reaction flask termed the hybrid (HYBR) route, yielding even thinner H₂Ti₂O₅·H₂O nanowires on a large-scale. Switching to a concentrated halide acid (HX, where X = Cl, Br, I) system, SOLVO, SPPT, and HYBR routes were investigated. The resultant TEM images revealed that the rutile starting material yielded short rods, whereas the anatase seeds formed square or faceted materials.     

Dielectric properties of Sr3CuNb2O9 perovskite ceramics

The dielectric constant ? and loss tangent tanδ of Sr₃CuNb₂O₉ perovskite ceramics prepared by solid-state reactions have been measured at temperatures from 300 to 900 K and frequencies from 25 to 1 × 10⁶ Hz. The results demonstrate that the samples slowly cooled from the temperature of the final, high-temperature firing (1200°C) have relatively low permittivity (? ? 10) and dielectric losses (tanδ ? 0.005 at 1 kHz) at room temperature, with no strong dielectric dispersion and no prominent maxima in the temperature dependences of their permittivity and dielectric loss. The ceramics quenched from 1300°C exhibit a pronounced Debye-type low-frequency relaxation and strong dielectric dispersion in conjunction with high permittivity ? ? 2000 at low frequencies and/or high temperatures. The observed dielectric anomalies in the Sr₃CuNb₂O₉ ceramics can be understood in terms of Maxwell-Wagner relaxation at dielectric inhomogeneities associated with the quenching-induced difference in oxygen-vacancy concentration between the grain bulk and surface layer.     

Naturally occurring contamination in the Mancos Shale

Some uranium mill tailings disposal cells were constructed on dark-gray shale of the Upper Cretaceous Mancos Shale. Shale of this formation contains contaminants similar to those in mill tailings. To establish the contributions derived from the Mancos, we sampled 51 locations in Colorado, New Mexico, and Utah. Many of the groundwater samples were saline with nitrate, selenium, and uranium concentrations commonly exceeding 250,?000, 1000, and 200 μg/L, respectively. Higher concentrations were limited to groundwater associated with shale beds, but were not correlated with geographic area, stratigraphic position, or source of water. The elevated concentrations suggest that naturally occurring contamination should be considered when evaluating groundwater cleanup levels. At several locations, seep water was yellow or red, caused in part by dissolved organic carbon concentrations up to 280 mg/L. Most seeps had (234)U to (238)U activity ratios greater than 2, indicating preferential leaching of (234)U. Seeps were slightly enriched in (18)O relative to the meteoric water line, indicating limited evaporation. Conceptually, major ion chemical reactions are dominated by calcite dissolution following proton release from pyrite oxidation and subsequent exchange by calcium for sodium residing on clay mineral exchange sites. Contaminants are likely released from organic matter and mineral surfaces during weathering.     

Loline alkaloids in tall fescue hay and seed and their relationship to summer fescue toxicosis in cattle

In three trials, young Holstein steers housed in restraint type crates in a controlled environment room were fed tall fescue hay or seed diets to determine the ability of the diets to produce signs of summer syndrome. Trial 1 examined the effects of dehydration and extended storage of G1-307 fescue compared to alfalfa on dairy steers. Calves fed G1-307 fescue had lower daily feed intake, higher rectal temperatures and respiration rates, and lost 13.4 kg more body weight during the experimental period as compared to those fed alfalfa hay. In trial 2, benomyl (a systemic fungicide) was used to eliminate the fungus Epichloe typhina from treated G1-307 fescue plants. Steers fed the treated G1-307 fescue progeny had higher daily intakes, lower rectal temperature, lower respiration rates, and lost less body weight over the trial period as compared with those fed untreated G1-307 fescue. Kenhy tall fescue seeds with and without analyzable N-acetyl and N-formyl loline alkaloids and a control diet were fed in trial 3. Steers fed the seed with the loline alkaloids had reduced intake, higher rectal temperatures, and lost 10.9 kg more body weight over the trial period than steers fed seed that did not contain loline alkaloids.     

烟草转化株烟碱含量对其向降烟碱转化程度的影响

在烟株生长早期鉴别转化株,需要对转化株的烟碱转化进行诱导以使转化性状充分表达,但同一基因型材料在不同生长条件下经诱导产生的烟碱转化程度存在较大差异。本试验旨在探讨转化株的烟碱基础含量对诱导后烟碱转化程度的影响。结果表明由于打顶和增施氮肥造成烟碱基础含量增高可显著降低诱导后的烟碱转化程度。在温室条件下,通过调节氮肥施用量获得具有不同烟碱含量的植株,以白肋烟TN90的高转化品系为材料的试验表明,当烟碱基础含量超过2.0%时,烟碱向降烟碱转化不完全,随着烟碱含量的增高,烟碱转化百分率几乎呈线形下降。采用由高转化系和非转化系杂交的F1植株为材料进行试验,发现烟碱转化百分率随烟碱含量下降的趋势更加明显。采用低转化株的自交分离后代进行试验,发现在低施氮水平下对转化株进行诱导和鉴别的有效性高于在高施氮条件下对转化株的诱导和鉴别。因此,使烟株维持较低的烟碱水平有利于转化株特别是低转化株的有效鉴别。      

Metal Residues in Farm-Raised Channel Catfish, Rainbow Trout, and Red Swamp Crayfish from the Southern U.S.

ABSTRACT: Farm-raised channel catfish (Ictalurus punctatus), rainbow trout (Oncorhynchus mykiss), and red swamp crayfish (Procambarus clarkii) were collected from production and processing sites across the southern U.S. and analyzed for barium, cadmium, copper, chromium, silver, lead, arsenic, selenium, and mercury. Average metal residues were much lower than recommended safety limits. Residues of barium, copper, and mercury were slightly higher in crayfish than catfish or trout. Selenium was higher in crayfish and trout than catfish, and lead was higher in catfish and trout than crayfish. Residues of mercury in all samples were much lower than the FDA's Action Limit (1 ppm) for mercury in the edible tissue of fish.     

Land-Use Planning’s Role in Urban Forest Strategies: Recent Local Government Approaches in Australia

Many urban development processes, supported by land-use planning, negatively impact urban trees. Urban forest strategies are one approach local governments take to protect and increase urban trees. We evaluate connections between urban forest strategies and land-use planning to achieve tree cover on private property, through a review of 18 Australian local government strategies. We highlight the importance of state-level policies for local land-use planning, and conclude that if state-level land-use planning is to aid the protection and enhancement of urban trees, more active engagement with and explicit links to urban forest strategies at both local and state levels is needed.     

Depression in adolescence.

Adolescence is an important developmental period for understanding the nature, course, and treatment of depression. Recent research concerned with depressive mood, syndromes, and disorders during adolescence is reviewed, including investigations of the prevalence, course, risk factors, and prevention and treatment programs for each of these 3 levels of depressive phenomena in adolescence. A broad biopsychosocial perspective on adolescent depression is recommended, and possible directions for future integrative research are proposed. Based on current research and knowledge, implications for research, program, and national policy are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)