Carbon dioxide hydrate and floods on Mars

Ground ice on Mars probably consists largely of carbon dioxide hydrate, CO(2) . 6H(2)O. This hydrate dissociates upon release of pressure at temperatures between 0 degrees and 10 degrees C. The heat capacity of the ground would be sufficient to produce up to 4 percent (by volume) of water at a rate equal to that at which it can be drained away. Catastrophic dissociation of carbon dioxide hydrate during some past epoch when the near surface temperature was in this range would have produced chaotic terrain and flood channels.     

Soil compressibility and penetrability of an Oxisol from southern Brazil, as affected by long-term tillage systems

The precompression stress value defines the transition from the reloading curve to the virgin compression line in the stress–strain curve, which can be used to quantify the highest load or the most intense predrying previously applied to the soil. Thus, in soils with well-defined structured soil horizons, each layer can be characterized by such mechanical strength. Penetration resistance measurements, on the other hand, can be used to determine total soil strength profiles in the field. The effect of long-term tillage systems on physical and mechanical properties was determined in undisturbed and remolded samples collected at 5 and 15 cm depth, 6 months after applying no-till (NT), chisel plow (CP), and conventional tillage (CT) treatments, along with the application of mineral fertilizer and poultry litter. The compressibility tests were performed under confined conditions, with normal loads varying from 10 to 400 kPa after a defined predrying to −6 or −30 kPa. Penetration resistance was determined in the field, after seeding, in three positions: seeding row (SR), untrafficked interrow (UI), and recently trafficked interrow (TI). No-till system showed greater soil resistance to deformation than tilled treatments, as determined by the higher precompression stress and lower coefficient of compressibility. When original soil structure was destroyed (remolded samples), smaller differences were found. The application of extra organic matter (poultry litter) resulted in a reduction of precompression stress in undisturbed samples. Penetration resistance profiles showed greater differences among tillage treatments in the upper layer of the untrafficked interrow, where NT system showed the higher values. Smaller differences were found in the seeding row (with lower values) and in recently trafficked interrow (with higher values), showing that even traffic with a light tractor after soil tillage reduced drastically the effect of previous tillage by loosening up the soil. On the other hand, the tool used to cut the soil and to open the furrow for seeding, incorporated in the direct seeding machine, was sufficient to realleviate surface soil compaction.     

Heavy metals in recent sediments and bottom-fish under the influence of tanneries in South Brazil

Selected metals were evaluated in surface sediments from Cadeia and Feitoria Rivers (Brazil), potentially affected by tanneries. Statistical factor analysis of sediment data allowed the identification of critical} metals and priority areas for biological monitoring, i.e., chromium and mercury at the lower course of Feitoria River. Non-piscivorous bottom-fish from the species Rineloricaria cadeae (violinha) were collected at reference and contaminated sites. Chromium was undetected} in fish tissues, and mercury accumulated in individuals living in contact with contaminated deposits. Mercury contents in fish were below World Health Organization quality standard for human consumption (0.5 μg/g). The ratio of total mercury content in fish (wet weight) to sediment (dry weight, <63 μm) was 0.5 and 0.7 at reference and contaminated sites, respectively. A risk assessment based on hazard index showed that maximum consumption of fish from contaminated site by human population should be 32 g/day, while at reference site the allowable amount could reach 140 g/day.     

Toxicity and metabolism of the conjugates of 3-nitropropanol and 3-nitropropionic acid in forages poisonous to livestock

Glycosides of 3-nitro-1-propanol (nitropropanol) and glucose esters of 3-nitro-1-propanoic acid (nitropropionic acid) occur in many forages distributed throughout the world. Systemically, nitropropionic acid irreversibly inactivates succinate dehydrogenase, thereby blocking ATP formation. Nitropropanol is not toxic per se in mammals but is converted to nitropropionic acid by hepatic alcohol dehydrogenase. Nitrotoxins can be metabolized by rumen microbes, which may provide a mechanism for detoxification. At least 20 different ruminal bacteria are known to metabolize the nitrotoxins, but most appear to play a minor role in detoxification. Evidence suggests that an obligate anaerobic nitro-respiring bacterium, Denitrobacterium detoxificans, may be particularly important in conferring protection to animals consuming the nitrotoxins as this bacterium metabolizes the toxins at rates near those by mixed ruminal populations. Rates of ruminal nitrotoxin metabolism can be enhanced by modifying the rumen environment through dietary manipulations, which suggests in vivo enrichment of competent nitrotoxin-metabolizing bacteria such as D. detoxificans.     

Spatial patterns of magnetic susceptibility optimized by anisotropic correction in different Alisols in southern Amazonas,Brazil

Precision Agriculture - Changes in primary cover for agricultural crops in Amazonas region influence the phenomenon of spatial variability in soil properties. This phenomenon is still studied...     

Effects of hydroxycinnamic acid esters on sweetpotato weevil feeding and oviposition and interactions with Bacillus thuringiensis proteins

Journal of Pest Science - Sweetpotato weevil (SPW) pest management is challenging because the pest target is sub-terranean, so the application of pesticides is impractical and usually ineffective....     

Enrichment of (E)-resveratrol from peanut byproduct with molecularly imprinted polymers

Molecularly imprinted solid phase extraction (MISPE) has been employed to isolate and concentrate bioactive polyphenols from peanut press waste. To this end, a molecularly imprinted polymer (MIP) templated with the phytoalexin (E)-resveratrol has been prepared via self-assembly with the functional monomer 4-vinylpyridine (4VP) in a 1:3 molar ratio. Subsequent molecular interrogation of the MIP binding sites demonstrated preferential structural selectivity for (E)-resveratrol with respect to other structurally related naturally occurring compounds. This selectivity was subsequently exploited to achieve substantial sample cleanup of peanut press waste under aqueous conditions with significant enrichment of (E)-resveratrol (>60 fold) requiring minimal sample preparation.