Potential terrain controls on soil color, texture contrast and grain-size deposition for the original catena landscape in Uganda     

David J. Brown  Murray K. Clayton  Kevin McSweeney 《Geoderma》2004,122(1):51-72

Inspired by the catena concept, we returned to the landscape of origin for this idea in central Uganda and applied quantitative soil-landscape-modeling techniques to the study of soil formation. In particular, we employed Generalized Least Squares (GLS) regression to identify potential terrain (and other) controls on surface texture with the goal of explaining texture contrast formation for well-drained red soils, and fluvial deposition for yellow-gray lowland soils. Well-drained red soils and poorly drained yellow-gray soils were identified using a high-resolution spectroradiometer and soil redness was highly correlated with a measure of elevation above the valley floor. For the yellow-gray soils, sand content and sand grain size increased with greater slope gradient and in converging areas—evidence supporting fluvial control of surface soil composition. For red soils, texture contrast increased on lower backslopes, decreased over ferricrete-rich parent material, and had no significant association with either infiltration- or runoff-influenced locations. Surprisingly, texture contrast was also reduced or even inverted on fine scale convexities (<18 m in diameter). These findings were consistent with the following theoretical processes: (1) sand deposition on lower-backslopes, increasing texture contrast; (2) ferricrete weathering at the soil surface, reducing texture contrast; and (3) texture contrast inversion through termite turbation. A number of techniques proved useful in this study: (a) the use of GLS regression supported the interpretation of model coefficients in an explicitly spatial context; (b) thin-plate splines provided a flexible means of controlling the spatial scale of terrain index computation; and (c) the development of a new downslope-looking Elevation Above Stream (EASy) terrain index provided a powerful tool for the identification of poorly drained soils—a tool that could have applications in a variety of landscapes and environments. Overall, we found that the catena concept as a soil-terrain-modeling approach worked best on lower, less well-drained, depositional landscape components. For the well-drained portion of this landscape, there was little evidence to suggest that soil formation was controlled by hillslope hydrology as proposed by the catena concept. The catena concept interpreted in a broad sense challenges pedologists to explicitly link soil geographic patterns with specific soil forming processes and environmental controls—an approach that proved valuable in this study.  相似文献   

Fish species identification using PCR-RFLP analysis and lab-on-a-chip capillary electrophoresis: application to detect white fish species in food products and an interlaboratory study   总被引：1，自引：0，他引：1  

Dooley JJ  Sage HD  Clarke MA  Brown HM  Garrett SD 《Journal of agricultural and food chemistry》2005,53(9):3348-3357

Identification of 10 white fish species associated with U.K. food products was achieved using PCR-RFLP of the mitochondrial cytochrome b gene. Use of lab-on-a-chip capillary electrophoresis for end-point analysis enabled accurate sizing of DNA fragments and identification of fish species at a level of 5% (w/w) in a fish admixture. One restriction enzyme, DdeI, allowed discrimination of eight species. When combined with NlaIII and HaeIII, specific profiles for all 10 species were generated. The method was applied to a range of products and subjected to an interlaboratory study carried out by five U.K. food control laboratories. One hundred percent correct identification of single species samples and six of nine admixture samples was achieved by all laboratories. The results indicated that fish species identification could be carried out using a database of PCR-RFLP profiles without the need for reference materials.  相似文献   

Gel filtration and disc gel electrophoresis of tomato pectic substances.     

E R Stein  H E Brown 《Journal of agricultural and food chemistry》1975,23(3):526-529

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Variation of glucosinolates in vegetable crops of Brassica oleracea   总被引：10，自引：0，他引：10  

Kushad MM  Brown AF  Kurilich AC  Juvik JA  Klein BP  Wallig MA  Jeffery EH 《Journal of agricultural and food chemistry》1999,47(4):1541-1548

Glucosinolates were evaluated in 5 groups and 65 accessions of Brassica oleracea (50 broccoli, 4 Brussels sprouts, 6 cabbage, 3 cauliflower, and 2 kale) grown under uniform cultural conditions. Glucosinolates and their concentrations varied among the different groups and within each group. The predominant glucosinolates in broccoli were 4-methylsulfinylbutyl glucosinolate (glucoraphanin), 3-butenyl glucosinolate (gluconapin), and 3-indolylmethyl glucosinoate (glucobrassicin). Glucoraphanin concentration in broccoli ranged from 0.8 micromol g(-1) DW in EV6-1 to 21.7 micromol g(-1) DW in Brigadier. Concentrations of the other glucosinolates in broccoli varied similarly over a wide range. In Brussels sprouts, cabbage, cauliflower, and kale, the predominant glucosinolates were sinigrin (8.9, 7.8, 9.3, and 10.4 micromol g(-1) DW, respectively) and glucobrassicin (3.2, 0.9, 1.3, and 1.2 micromol g(-1) DW, respectively). Brussels sprouts also had significant amounts of gluconapin (6.9 micromol g(-1) DW). Wide variations in glucosinolate content among genotypes suggest differences in their health-promoting properties and the opportunity for enhancement of their levels through genetic manipulation.  相似文献   

Evaluation of methods to derive pesticide degradation parameters for regulatory modelling   总被引：2，自引：0，他引：2  

Sabine Beulke  Colin D. Brown 《Biology and Fertility of Soils》2001,33(6):558-564

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Hay strewing, brush harvesting of seed and soil disturbance as tools for the enhancement of botanical diversity in grasslands   总被引：1，自引：0，他引：1  

Andrew R. Edwards  Simon R. Mortimer  Clare S. Lawson  Duncan B. Westbury  Stephanie J. Harris  Ben A. Woodcock  Valerie K. Brown 《Biological conservation》2007,134(3):372-382

Since the middle of the last century agricultural intensification within Europe has led to a drastic decline in the extent of botanically diverse grasslands. Whilst measures to enhance the diversity of agriculturally-improved grasslands are in place, success has often been limited. One of the primary factors limiting success is the paucity of sources of propagules of desirable species in the surrounding landscape. The restoration of two contrasting grassland types (lowland hay meadow and chalk grassland) was examined using a replicated block experiment to assess the effectiveness of two methods of seed application (hay strewing and brush harvesting) and two methods of pre-treatment disturbance (power harrowing and turf stripping). The resulting changes in botanical composition were monitored for 4 years. Seed addition by both methods resulted in significant temporal trends in plant species composition and increases in plant species richness, which were further enhanced by disturbance. Power harrowing increased the effectiveness of the seed addition treatments at the lowland hay meadow site. At the chalk grassland site a more severe disturbance created by turf stripping was used and shown to be preferable. Whilst both hay strewing and brush harvesting increased plant species richness, hay strewing was more effective at creating a sward similar to that of the donor site. Soil disturbance and seed application rate at the recipient site and timing of the hay cut at the donor site are all factors to be considered prior to the commencement of restoration management.  相似文献   

Increased crop yields following application of Bacillus penetrans to field plots infested with Meloidogyne incognita     

Stephen M. Brown  James L. Kepner  Grover C. Smart 《Soil biology & biochemistry》1985,17(4):483-486

We found Bacillus penetrans to be pathogenic to Meloidogyne incognita under field conditions. B. penetrans was added to the soil of field plots into which tobacco, soybeans or winter vetch were planted in sequence during 1981 and 1982. Tobacco and winter vetch (1981 and 1982) and soybeans in 1982 showed trends of increasing yields with decreasing pathogenicity of M. incognita. There was insufficient evidence to enable one to declare a similar trend for soybeans in 1981. B. penetrans reduced yield losses caused by M. incognita 23% for tobacco 1981, 38% for winter vetch 1981, 24% for tobacco 1982, 35% for soybeans 1982 and 55% for winter vetch 1982.  相似文献   

Pharmacokinetics of a slow-release formulation of soybean isoflavones in healthy postmenopausal women     

Setchell KD  Brzezinski A  Brown NM  Desai PB  Melhem M  Meredith T  Zimmer-Nechimias L  Wolfe B  Cohen Y  Blatt Y 《Journal of agricultural and food chemistry》2005,53(6):1938-1944

Pharmacokinetic studies of soybean isoflavones have shown that following oral ingestion, the two major isoflavones, daidzin and genistin, are hydrolyzed in the intestine, rapidly absorbed into the peripheral circulation, and eliminated from the body with a terminal half-life of 7-8 h. These characteristics make maintenance of steady-state plasma isoflavone concentrations difficult to attain unless there is repeated daily ingestion of foods or supplements containing isoflavones. In an attempt to sustain more constant plasma isoflavone concentrations, a new slow-release formulation of a soybean isoflavone extract was prepared by microencapsulation with a mixture of hydroxypropylcellulose and ethylcellulose to alter its dissolution characteristics. In vitro experiments confirmed slow aqueous dissolution of isoflavones from this formulation when compared with the conventional isoflavone extract. The pharmacokinetics of this slow-release isoflavone extract was studied in 10 healthy postmenopausal women after oral administration of a single capsule containing the equivalent of 22.3 mg of genistein and 7.47 mg of daidzein expressed as aglycons. A comparison of the key pharmacokinetic parameters obtained in this study with those established in extensive studies performed previously in this laboratory indicated that the mean residence time of genistein and daidzein increased 2-fold with microencapsulation. These findings are indicative of a decreased rate of absorption, consistent with the observed slow in vitro dissolution rate. These findings show that it is feasible to employ polymer matrices that slow the aqueous dissolution for preparing sustained-release formulations of soy isoflavones. Further studies to optimize such formulations are warranted.  相似文献   

Determination of caffeine, theobromine, and theophylline in standard reference material 2384, baking chocolate, using reversed-phase liquid chromatography     

Thomas JB  Yen JH  Schantz MM  Porter BJ  Sharpless KE 《Journal of agricultural and food chemistry》2004,52(11):3259-3263

A rapid and selective isocratic reversed-phase liquid chromatographic method has been developed at the National Institute of Standards and Technology to simultaneously measure caffeine, theobromine, and theophylline in a food-matrix standard reference material (SRM) 2384, Baking Chocolate. The method uses isocratic elution with a mobile phase composition (volume fractions) of 10% acetronitrile/90% water (pH adjusted to 2.5 using acetic acid) at a flow rate of 1.5 mL/min with ultraviolet absorbance detection (274 nm). Total elution time for these analytes is less than 15 min. Concentration levels of caffeine, theobromine, and theophylline were measured in single 1-g samples taken from each of eight bars of chocolate over an eight-day period. Samples were defatted with hexane, and beta-hydroxyethyltheophylline was added as the internal standard. The repeatability for the caffeine, theobromine, and theophylline measurements was 5.1, 2.3, and 1.9%, respectively. The limit of quantitation for all analytes was <100 ng/mL. The measurements from this method were used in the value-assignment of caffeine, theobromine, and theophylline in SRM 2384.  相似文献   

The effects of the insecticide chlorpyrifos on spider and Collembola communities     

Michelle T. Fountain  Valerie K. Brown  Alan C. Gange  William O.C. Symondson  Phil J. Murray 《Pedobiologia》2007,51(2):147-158

The effects of chlorpyrifos on aquatic systems are well documented. However, the consequences of the pesticide on soil food webs are poorly understood. In this field study, we hypothesised that the addition of a soil insecticide to an area of upland grassland would impact spider and Collembola communities by decreasing numbers of spiders, consequently, causing an increase in detritivore numbers and diversity.Chlorpyrifos was added to plots on an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps (activity density) and identified to species.Twelve species of Collembola were identified from the insecticide-treated and control plots. Species diversity, richness and evenness were all reduced in the chlorpyrifos plots, although the total number of Collembola increased ten-fold despite the abundance of some spider species being reduced. The dominant collembolan in the insecticide-treated plots was Ceratophysella denticulata, accounting for over 95% of the population.Forty-three species of spider were identified. There were a reduced number of spiders in insecticide-treated plots due mainly to a lower number of the linyphiid, Tiso vagans. However, there was no significant difference in spider diversity between the control and insecticide treatments.We discuss possible explanations for the increase in abundance of one collembolan species in response to chlorpyrifos and the consequences of this. The study emphasises the importance of understanding the effects of soil management practices on soil biodiversity, which is under increasing pressure from land development and food production. It also highlights the need for identification of soil invertebrates to an ‘appropriate’ taxonomic level for biodiversity estimates.  相似文献