The determination of flight-lane separations for the aerial application of herbicides

Deposits of chemical on the target must achieve a satisfactory degree of uniformity for economic and effective weed control, especially when contact-activity chemicals are applied. Methods of measuring spray deposits include droplet-stain measurement, colorimetry and fluorimetry. Deposit data have been obtained over several years from a wide range of fixed-wing and rotary-wing aircraft, using a system designed to produce rapid results. The choice of suitable flight-lane separations, and the need to make adjustments to the spray equipment, were assessed by measuring spray deposits from a single flight line and analysing the results by either an electronic calculator or microcomputer. The analysis can establish the probable degree of unevenness for the overall spray application for various flight-lane separations and, with the additional input of dose-response characteristics, can also indicate the likely level of weed control. The economic penalties arising from the maldistribution of herbicides by the use of incorrect flight-lane separations are illustrated by an example of a residual herbicide applied to a winter cereal in the United Kingdom. The use of non-optimum flight-lane separations may cause large reductions both in crop yield and in return on the farmer's investment.     

Phase II-Inducing,Polyphenols Content and Antioxidant Capacity of Corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) from Phenotypes of White,Blue, Red and Purple Colors Processed into Masa and Tortillas

White, blue, red and purple corns (Zea mays L.) were lime-cooked to obtain masa for tortillas. The total phenolics and anthocyanins content, antioxidant activity expressed as total reducing power (TRP), peroxyl radical bleaching (PRAC), total antioxidant activity (TAA) and quinone reductase (QR) induction in the murine hepatoma (Hepa 1 c1c7 cell line) as a biological marker for phase II detoxification enzymes were investigated. Among the extracts prepared from raw corn varieties the highest concentration of total phenolics, anthocyanins, antioxidant index and induction of QR-inducing activity were found in the Veracruz 42 (Ver 42) genotype. The nixtamalization process (masa) reduced total phenolics, anthocyanins and antioxidant activities and the ability for QR induction when was compared to raw grain. Processing masa into tortillas also negatively affected total phenolics, anthocyanin concentration, antioxidant activities, and QR induction in the colored corn varieties. The blue variety and its corresponding masa and tortillas did not induce QR. Ver 42 genotype and their products (masa and tortilla) showed the greatest antioxidant activity and capacity to induce QR     

Evaluation of a Geonics EM31-3RT probe to delineate hydrologic regimes in a tile-drained field

A world-wide need to use water resources efficiently necessitates more effective approaches to study water and contaminant transport in soil. This study examined the effectiveness of a multi-receiver electromagnetic induction probe (Geonics EM31-3RT) and modeling software (EMIGMA) to delineate hydrological regimes at field scale. The site consisted of 20 (15 m × 15 m) tile-drained plots in Southern Ontario, Canada. Measurements of apparent soil electrical conductivity (EC_a) and magnetic susceptibility were obtained using the EM31-3RT in each plot at four distances (0, 2.25, 4.5 and 7.5 m) from the tile drain, and on three occasions (August 22, 26 and 29) in 2003. The EMIGMA was used to simulate a depth profile of electrical conductivity (EC_s) from EM31-3RT readings. The near-surface soil showed significantly (p < 0.01) smaller EC_a values than at greater depth. The EC_a measurements made directly over the tile drains were smaller than those observed further away due to the presence of the drains. Cluster analysis indicated that the largest EC_a values were at the lower elevations of the site related to the redistribution of moisture from higher elevations. The effect of tile drains and rainfall events on EC_a was simulated well by EMIGMA, with smaller EC_s values above the drains compared to further away, and showing an increase in EC_s in the near-surface soil after rain. This study suggests that EM31-3RT measurements combined with EMIGMA simulation of electrical conductivity can provide valuable information on depth profiles of EC_a and water dynamics in soil.     

Fate and kinetic modeling of reactivity of alkanesulfenic acids and thiosulfinates in model systems and onion homogenates

The dynamic changes in thiosulfinate profiles were studied in reaction systems containing a crude onion alliinase, S-alk(en)yl-L-cysteine sulfoxide substrates (1) and preformed thiosulfinates (4). Regioisomeric excesses of one of two possible heterologous 4 species (RS(O)SR', where R does not equal R') could be manipulated under conditions where alliinase, 1, and 4 levels were varied. Regioisomeric excesses could be explained by a thiosulfinate (4)/alkanesulfenic acid (2) trapping mechanism, with the greatest control over product profile governed by the rate of 2 generation in the system. The series of reactions existing in this dynamic reaction system was kinetically modeled with reasonable fits to the experimental data. The application of the 4/2 trapping strategy to manipulate thiosulfinate and related organosulfur product profiles in diluted onion homogenates was demonstrated using exogenous MeS(O)SMe (4a), PrS(O)SPr (4c), and AllS(O)SAll (4d) as the preformed thiosulfinate.     

Application of a soil core method to investigate the effect of oxygen concentration on denitrification

The effect of O₂ concentration on denitrification rate was investigated in sandy loam and clay loam soils. Oxygen at different concentrations and acetylene were recirculated through freshly-collected soil cores. Denitrification rates under anaerobic conditions with argon as the recirculating gas were also determined. The effect of O₂ on denitrification rate among cores could then be normalized by expressing the data as percent of the anaerobic rate. Denitrification rates were less than 2% of the anaerobic rate for O₂ concentrations greater than 3%, but greatly increased at concentrations below 0.5% O₂. For individual cores the denitrification rate increased 2- and 4-fold as the O₂ content of the recirculating gas was decreased from 20 to 5%. The pattern of denitrification rate versus O₂ concentration was very similar to that generated from the theoretical model of K. A. Smith, which describes the proportional anaerobic volume of soil aggregates as a function of O₂ concentration. A soil gas sampling probe is described which uses porous Gortcx tubing buried in horizontal soil layers. The recirculating gas in the denitrificating assay 4system could then be adjusted to match the soil O₂ content measured at the time of sampling.     

The magnetic stability of spin-dependent tunneling devices

The tunneling resistance between two ferromagnetic metal layers that are separated by a thin insulator depends on the relative orientation of the magnetization M of each layer. In a memory device, independent switching of the magnetically soft layer is achieved by making the other layer either exchange-biased or magnetically hard. The repeated reversal of M of the soft layer by field cycling can demagnetize the other magnetically hard layer and thus erase the tunnel junction's memory. The M of exchange-biased structures was stable at least to 10(7) cycles, whereas in hard structures, M generally decayed logarithmically with the number of field cycles. The decay was very sensitive to the thickness of the hard layer and the composition of the soft layer. However, no decay was observed when the moment reversal was accomplished by coherent rotation, establishing that demagnetization results from the formation and motion of domain walls in the soft layer during field cycling.     

West African HIV-2-related human retrovirus with attenuated cytopathicity

Clinical and seroepidemiological studies in West Africa indicate that human immunodeficiency virus type 2 (HIV-2) is widespread and associated with immunodeficiency states of variable degree. In this study, an isolate of HIV-2 from a patient in Senegal was molecularly cloned and characterized. This isolate (HIV-2ST) was shown by hybridization and restriction enzyme analysis to be more related to the prototype HIV-2ROD than to other human or primate retroviruses. Cultures of HIV-2ST showed genotypic polymorphism, and clones of the virus had transmembrane envelope glycoproteins of 30 and 42 kilodaltons. Unlike other immunodeficiency viruses, HIV-2ST did not cause cell death or induce cell fusion in peripheral blood lymphocytes or in any of four CD4+ cell lines tested. Although HIV-2ST entered cells by a CD4-dependent mechanism and replicated actively, cell-free transmission of the virus was retarded at the level of cell entry. These findings suggest that immunodeficiency viruses prevalent in West African populations are members of the HIV-2 virus group and that certain strains of this virus have attenuated virulence.     

External characteristics of the lateral aspect of the hoof differ between non-lame and lame horses

During a pre-purchase examination (PPE) there is always a debate about how clinical findings of the hoof different from ideal should be interpreted in relation to future lameness risk and/or unsuitability of the horse for the potential purchaser. The objectives of this study were to describe and compare external angular measurements, linear ratios and hoof capsule characteristics of non-lame and lame feet. Photographs of feet from 300 horses with foot pain and 25 non-lame horses were analysed. Hoof wall, heel and coronary band angles and hoof wall length and height, weight-bearing length, coronary band length and height of the coronary band at dorsal and palmar locations were measured and expressed as linear ratios.Mean hoof wall, heel and coronary band angles were larger in lame compared with non-lame feet; only the ratio of dorsal to palmar coronary band heights and the shape of the coronary band were significantly different between lame and non-lame horses. Growth rings were divergent and horn tubules were non-parallel in lameness of >3 months. At a PPE, a larger ratio of dorsal to palmar coronary band heights in one limb may be indicative of previous lameness in that foot. Changes in coronary band shape and divergent growth rings and horn tubules would suggest a longer duration.