Comparison of media to isolate Staphylococcus aureus from teat skin and milking unit liners.

Four procedures were compared for isolation of Staphylococcus aureus from swabbing solutions of teat skin and milking unit liners from commercial dairies. In 2 procedures, 0.1 ml of swabbing solutions were added to either 5 ml Vogel-Johnson or Baird Parker broth media and enriched at 37 degrees C, 4 h. Following enrichment, 0.1 ml culture was transferred to modified Baird-Parker agar and incubated at 37 degrees C, 48 h. In the other 2 procedures, 0.1 ml of swabbing solution was directly placed on either blood or modified Baird-Parker agar plates and incubated at 37 degrees C 48 h. Combining results from all methods, Staphylococcus aureus were isolated from 72 of 913 (7.9%) skin samples, and 34 of 268 liners (12.6%). On average, 43.1% (31/72) of the S. aureus isolates were found by the enrichment in liquid Vogel-Johnson procedure. The average isolation percentage for other methods ranged from 19.4% to 25.0%. Isolation of S. aureus from milking unit liner or teat skin swabbing solutions was approximately twice as likely after enrichment in Vogel-Johnson liquid media as opposed to other methods of isolation. This indicates that enrichment in Vogel-Johnson liquid media improved recovery of S. aureus from swabbing solutions.     

Effect of Mixing Time and Speed on Experimental Baking and Dough Testing with a 200 g Pin Mixer

Undermixing or overmixing the dough results in varied experimental loaf volumes. Bread preparation requires a trained baker to evaluate dough development and determine the stop points of the mixer. Instrumentation and electronic control of the dough mixer would allow for automatic mixing. This study used a 200 g mixer that provided an output signal during dough mixing to evaluate potential mixing stop points. The effect of varied mixing time on the baked loaf volume was tested by using three flours with protein contents of 10.6, 12.4, and 13.8%. Dough samples were undermixed, mixed to peak, and overmixed. Overmixing by 0.6 min reduced the loaf volume in all flours tested, by 16–50 cm³ at 90 rpm and by 29–68 cm³ at 118 rpm. When the high‐protein flour sample was undermixed, the largest baked loaves were produced, with an average volume of 922 cm³. A second objective studied the similarities and differences between a 200 g mixer and a 35 g mixograph. The same flours were mixed on both units. The mixing peaks for the 200 g mixer were normalized with the 35 g mixograph peaks. When flour and water were used, the mixing times for the 200 g mixer averaged 0.7, 1.2, and 1.6 min shorter than the 35 g mixograph, at 90, 104, and 118 rpm, respectively. Although both the 200 g mixer and the 35 g mixograph system look mechanically similar, they both have unique mechanical motion, speeds, and sample sizes. Their results may show similar trends, but their measured values are usually different. However, when other baking ingredients were included in the 200 g mixer at 90 rpm, the mixing times were within 0.2 min of the 35 g mixograph times for three of four flours.     

Spatial pattern and heterogeneity of soil properties in sand dunes under grazing and restoration in Horqin Sandy Land, Northern China

Applying a combination of classical and geostatistical methods, we identified soil properties and their spatial variation in a 5-year grazed sand dune (GSD5) and a 20-year recovered sand dune (RSD20) in Horqin Sandy Land, northern China. The paper assesses the effect of grazing, topography and vegetation restoration on spatial heterogeneity of soil properties. The results showed that soil organic carbon, total nitrogen, very fine sand (0.1–0.05 mm) content and their coefficients of variation were lower in GSD5 than in RSD20, while soil water contents (0–20 cm and 20–40 cm depths) were higher in GSD5 than in RSD20. Geostatistical analysis revealed that the spatial structured variance accounted for the largest proportion of total sample variance in soil properties at the measured scale under grazing and restoration. The spatial autocorrelation ranges were 66.30 m for soil organic carbon and 50.80 m for total nitrogen in GSD5 less than those in RSD20 (70.00 m and 76.10 m, respectively), while the spatial autocorrelation ranges of soil particle size fractions and soil water contents in RSD20 were less than those in GSD5. Kriging-interpolated maps also showed that the heterogeneity of soil organic carbon and total nitrogen and their degree of patch fragmentation were higher in GSD5 than in RSD20. These results suggested that continuous grazing resulted in an increase in spatial variability of soil nutrient and a decrease in spatial variability of soil particle size fractions and soil water content. Soil organic carbon and total nitrogen of sand dunes are associated closely with soil particle size fractions, relative height of sampling site and vegetation cover. Spatial patterns of soil properties are most strongly related to grazing, topography and plant-induced heterogeneity in sand dune ecosystems prone to wind erosion.     

Wind erosion and sand accumulation effects on soil properties in Horqin Sandy Farmland,Inner Mongolia

Rain-fed agriculture is widespread in Inner Mongolia, northern China, where wind erosion of farmland is very common because of sandy soil and dry, windy weather. However, very little is known about the effects of wind erosion on soil physical and chemical properties in this region. A field experiment was conducted in sandy farmland, where erosional and depositional gradients were established to evaluate the effects of wind erosion and leeward sand accumulation on soil texture, nutrient content, soil water, and soil temperature. The research showed that long term wind erosion could result in significant soil coarseness, infertility and dryness. Severe erosion reduced clay by 59.6%, organic C by 71.2%, total N by 67.4%, total P by 31.4%, available N by 64.5%, available P by 38.8%, and average soil water content by 51.8%, compared with non-eroded farmland in the study region. The sand fraction (particles > 0.05 mm), pH and ground-surface temperature increased by 6.2%, 3.7%, and 2.2 °C, respectively. Accumulated sand also caused a decrease in nutrients and soil water content. Under severe sand accumulation, clay was reduced by 2.0%, organic C by 19.3%, total N by 21.7%, total P by 13.7%, available N by 52.5%, and average soil water content by 26.6%. The sand fraction, pH, available P, and ground-surface temperature increased by 0.2%, 0.9%, 5.8% and 2.8 °C, respectively.     

Antioxidant content and free radical scavenging ability of fresh red pummelo [Citrus grandis (L.) Osbeck] juice and freeze-dried products

The antioxidative phytochemicals in various fruits and vegetables are widely recognized for their role in scavenging free radicals, which are involved in the etiology of many chronic diseases. Colored fruits are especially considered a quality trait that correlates with their nutritional values and health benefits. The specific aim of this study was to investigate the antioxidants in the juice and freeze-dried flesh and peel of red pummelo and their ability to scavenge free radicals and compare them with those in white pummelo juice. The total phenolic content of red pummelo juice extracted by methanol (8.3 mg/mL) was found to be significantly higher than that of white pummelo juice (5.6 mg/mL). The carotenoid content of red pummelo juice was also significantly higher than that in white pummelo juice. The contents of vitamin C and delta-tocopherol in red pummelo juice were 472 and 0.35 mug/mL, respectively. The ability of the antioxidants found in red pummelo juice to scavenge radicals were found by methanol extraction to approximate that of BHA and vitamin C with a rapid rate in a kinetic model. The ability of methanol extracts of freeze-dried peel and flesh from red pummelo to scavenge these radicals was 20-40% that of BHA and vitamin C effects. Fresh red pummelo juice is an excellent source of antioxidant compounds and exhibited great efficiency in scavenging different forms of free radicals including DPPH, superoxide anion, and hydrogen peroxide radicals.     

Colonization of buried cotton stems by microarthropods

Initial colonization of cotton stems by microarthropods proceeded more rapidly while buried in soil under laboratory conditions (20–23°C) than while buried in the field during the winter months when soil temperatures ranged from 5–10°C in the study area in the San Joaquin Valley of California. While 15 species were found frequently in cotton stems held in the laboratory for 20 weeks, only seven species were found in field buried stems. Arthropods found under both conditions were a species of pyemotid mite; an astigmatid mite, Tyrophagus dimidiatus; two collembolans, Proisotoma minuta and Tullbergia sp.; and a sciarid fly larval stage, Bradysia impatiens. Even though the soils at teh field sites possessed a number of microarthropods in common, the stem colonization at each site was restricted to a single group which differed from each of the other sites. Microenvironments affect stem colonization patterns by microarthropods but microarthropods did not appear to have a significant influence on early cotton stem decomposition rates nor was there evidence that their activities reduced Verticillium microsclerotia populations.     

Commercial Seed Lots Exhibit Reduced Seed Dormancy in Comparison to Wild Seed Lots of Echinacea purpurea

Seed germination patterns were studied in E. purpurea (L.) Moench grouped by seed source, one group of seven lots from commercially cultivated populations and a second group of nine lots regenerated from ex situ conserved wild populations. Germination tests were conducted in a growth chamber in light (40 μmol·m(-2)·s(-1)) or darkness at 25 °C for 20 days after soaking the seeds in water for 10 minutes. Except for two seed lots from wild populations, better germination was observed for commercially cultivated populations in light (90% mean among seed lots, ranging from 82% to 95%) and in darkness (88% mean among seed lots, ranging from 82% to 97%) than for wild populations in light (56% mean among seed lots, ranging from 9% to 92%) or in darkness (37% mean among seed lots, ranging from 4% to 78%). No germination difference was measured between treatments in light and darkness in the commercially cultivated populations, but significant differences were noted for treatments among wild populations. These results suggest that repeated cycles of sowing seeds during cultivation without treatments for dormancy release resulted in reduced seed dormancy in E. purpurea.     

Modeling the survival of two soilborne pathogens under dry structural solarization

ABSTRACT Structural (space) solarization of a closed, empty greenhouse for sanitation involves dry heating to 60 degrees C and higher and low relative humidity (RH), under a fluctuating temperature and RH regime. Survival of inocula of Fusarium oxysporum f. sp. radicis-lycopersici and Sclerotium rolfsii during structural solarization was studied for 4 years (total of 12 experiments) in an attempt to develop a dynamic model for expressing the thermal inactivation of the pathogens. After 20 days of exposure, the populations of F. oxysporum f. sp. radicis-lycopersici and S. rolfsii were reduced by 69 to 95% and by 47.5 to 100%, respectively. The Weibull distribution model was applied to describe pathogen survival. The Weibull rate parameter, b, was found to follow an exponential (for F. oxysporum f. sp. radicis-lycopersici) and the Fermi (for S. rolfsii) functions at constant temperatures. To improve the applicability of the model, fluctuating conditions of both temperature and RH were utilized. The Weibull distribution derivative, expressed as a function of temperature and moisture, was numerically integrated to estimate survival of inocula exposed to structural solarization. Deviations between experimental and calculated values derived from the model were quite small and the coefficient of determination (R (2)) values ranged from 0.83 to 0.99 in 9 of 12 experiments, indicating that ambient RH data should be considered. Structural solarization for sanitation could be a viable component in integrated pest management programs.