Comparison of oyster shell and calcium hydroxide as liming materials for immobilizing cadmium in upland soil

Cadmium is both readily available and highly toxic to plants and animals. Our objectives were to evaluate the effect of oyster shell as a liming material on reducing plant cadmium (Cd) uptake and to compare oyster shell and Ca(OH)₂, a common liming material in Korea. Ground oyster shell and Ca(OH)₂ were applied at 0, 2, 4, and 8 Mg Ca per hectare to an upland soil contaminated manually with CdSO₄ (total Cd 8.96 mg kg^?1). Radish (Raphanus sativa L.) was sown on the contaminated soil. Oyster shell was less effective at increasing soil pH and net negative charge than Ca(OH)₂, but more effective at suppressing radish Cd uptake in both roots and shoots. The portion of Cd that is strongly bound to soil (fraction 5) increased more with oyster shell than with Ca(OH)₂. Radish plant Cd concentration was positively correlated with 0.1 N HCl-extractable Cd and negatively correlated with the residual Cd fraction (F5), indicating that an increase in the strongly bound Cd fraction played an important role in reducing radish Cd uptake in soil to which oyster shell was applied. The greater potential of oyster shell to decrease Cd extractability in soil and plant Cd uptake compared to Ca(OH)₂ might be attributed to the layered morphology of oyster shells. Based on these results, oyster shell could be a very good alternative liming material to reduce Cd phytoavailability in Cd-contaminated soil.     

Kepler-36: a pair of planets with neighboring orbits and dissimilar densities

In the solar system, the planets' compositions vary with orbital distance, with rocky planets in close orbits and lower-density gas giants in wider orbits. The detection of close-in giant planets around other stars was the first clue that this pattern is not universal and that planets' orbits can change substantially after their formation. Here, we report another violation of the orbit-composition pattern: two planets orbiting the same star with orbital distances differing by only 10% and densities differing by a factor of 8. One planet is likely a rocky "super-Earth," whereas the other is more akin to Neptune. These planets are 20 times more closely spaced and have a larger density contrast than any adjacent pair of planets in the solar system.     

Alteration of gymnosperm and angiosperm lignin during decomposition in forest humus layers

In the present investigation an attempt was made to characterize lignin decomposition in three forest humus profiles by the examination of their contents of simple lignin-derived phenolic compounds obtained from alkaline CuO oxidation. The total amounts of p-hydroxybenzoic, syringic, vanillic, p-coumaric and ferulic acids, p-hydroxybenzaldehyde, syringaldehyde and vanillin were determined. The acid to aldehyde weight ratios of the syringyl and vanillyl units, the weight ratio p-coumaric/ferulic acids and the weight ratios of syringyl and cinnamyl phenols, respectively, to vanillyl phenols were used for the characterization of the gymnosperm and angiosperm lignin in different stages of the decomposition process. The patterns of these parameters with depht point to a considerable decomposition and chemical alteration of the lignin molecule during biodegradation.     

Quantitative and qualitative aspects of a developing rhizosphere microflora of hydroponically grown maize seedlings

The roots of 7-day-old hydroponically grown maize seedlings inoculated with a soil suspension 2 days after sowing are mostly inhabited by shorter rods and occasionally by actinomycete-like filaments, as seen by scanning electron microscopy. The density of the bacterial cover increases from 39 × 10³ bacteria/mm² in the region where root hairs are just emerging to 63 × 10³ in the root hair zone 10 mm below the emerging secondary roots, and 188 × 10³ in the oldest part 10 mm below the grain. In this region the bacterial cover can locally form a coherent multilayer. The average area covered by 1 bacterium is 1.04μm² as measured by means of an image analyser. The percentage of the root area covered by its microflora, presuming a monolayer, is therefore 4%, 7% and 20%, respectively, of the three root zones under investigation. With an average dry weight of 0.64pg/cell all the 1.2 × 10⁹ rhizoplane bacteria/g root dry matter only account for less than 0.1% of the root weight. The microbial population adapted to the rhizosphere has very simple nutritional demands. Whereas 65% of the soil microflora isolated on yeast extract grows on the simple aforementioned medium, the value is 92% for the rhizosphere organisms. In spite of appreciable amounts of vitamins found in the inoculated nutrient solution, the growth of vitamin requiring species is not stimulated compared to the soil population. The same is true for amino acids.     

Interaction of maize roots and rhizosphere microorganisms

The interaction between the roots of Zea mays L. and its rhizosphere microflora was studied in nutrient solution with respect to two exemplary aspects - water soluble vitamins and the four most frequent carbohydrates. The exudation of vitamins and sugars into the medium is increased in a solid substrate (glass-ballotini simulating soil structure) in comparison with nutrient solution only. The amounts of vitamins released (1 to 421 ng per plant) are high enough for a pronounced influence on the rhizosphere microflora to be expected. However, the microbial population feeding on the exudates has very simple nutritional demands. In spite of appreciable amounts of vitamins found in the inoculated nutrient solution, the growth of vitamin requiring species is not stimulated compared to the soil population. The roots are mostly inhabited by shorter rods and occasionally by actinomycete-like filaments. The percentage of the root area covered by its microflora, assuming a monolayer, is 4% in the root region where root hairs are just emerging, 7% in the root hair zone and 20% in the oldest part of the roots, 10 mm below the grain. In the presence of rhizosphere microorganisms, root dry weight is lower than that of axenically grown plants because the diameter of the primary root is diminished. In addition, the vitamin and sugar content of the root is affected by rhizosphere microorganisms. The results can be interpreted as an indication that phytohormones may participate in interactions between roots and bacteria.     

Eating at fast-food restaurants is associated with dietary intake, demographic, psychosocial and behavioural factors among African Americans in North Carolina

OBJECTIVE: To examine associations of the frequency of eating at fast-food restaurants with demographic, behavioural and psychosocial factors and dietary intake in African American adults. METHODS: Self-reported data from a population-based cross-sectional survey of 658 African Americans, aged 20-70 years, in North Carolina. An 11-page questionnaire assessed eating at fast-food restaurants, demographic, behavioural and diet-related psychosocial factors, and dietary intake (fruit, vegetable, total fat and saturated fat intakes, and fat-related dietary behaviours). RESULTS: The participants were aged 43.9+/-11.6 years (mean+/-standard deviation), 41% were male, 37% were college graduates and 75% were overweight or obese. Seventy-six per cent reported eating at fast-food restaurants during the previous 3 months: 4% usually, 22% often and 50% sometimes. Frequency of eating at fast-food restaurants was positively associated with total fat and saturated fat intakes and fat-related dietary behaviours (P<0.0001) and inversely associated with vegetable intake (P<0.05). For example, mean daily fat intake was 39.0 g for usually/often respondents and 28.3 g for those reporting rare/never eating at fast-food restaurants. Participants who reported usual/often eating at fast-food restaurants were younger, never married, obese, physically inactive and multivitamin non-users (all P<0.01). Frequency of eating at fast-food restaurants was positively associated with fair/poor self-rated health, weak belief in a diet-cancer relationship, low self-efficacy for healthy eating, weight dissatisfaction, and perceived difficulties of preparing healthy meals and ordering healthy foods in restaurants (all P<0.05). Frequency of eating at fast-food restaurants did not differ significantly by sex, education, smoking, ability to purchase healthy foods or knowledge of the Food Guide Pyramid. CONCLUSIONS: Eating at fast-food restaurants is associated with higher fat and lower vegetable intakes in African Americans. Interventions to reduce fast-food consumption and obesity in African Americans should consider demographic and behavioural characteristics and address attitudes about diet-disease relationships and convenience barriers to healthy eating.     

Immunopathogenesis and immunotherapy of Culicoides hypersensitivity in horses: an update

Culicoides hypersensitivity (CH) is a strongly pruritic dermatitis of horses, characterised histologically by mixed perivascular to diffuse cellular infiltrates of mononuclear cells and eosinophils, and caused by helper T cell (Th)2, immunoglobulin (Ig)E-mediated reactions to antigens present in the saliva of biting Culicoides midges. As treatment of CH is still not satisfactory, a better knowledge of the pathogenesis of CH is needed for the development of new therapeutic modalities. Accordingly, availability of pure Culicoides allergens instead of crude whole body extracts is essential for the improvement of in vitro diagnosis of CH and development of a more effective allergen immunotherapy (AIT). Beside the Th2 cytokines interleukin (IL)-4 and IL-13, recent studies have shown the involvement of thymic stromal lymphopoietin, IL-5 and IL-31 in the pathogenesis of CH. The importance of IL-5 and IL-31 has been confirmed through targeting these cytokines by active immunisation of CH patients, resulting in a significant decrease of CH lesion scores. Thirty Culicoides salivary allergens have been described over the last 10 years and produced as pure recombinant (r-) proteins. Use of a protein microarray has allowed the identification of the most relevant Culicoides r-allergens for CH in central and northern Europe. An immunisation protocol has been developed for preventive AIT against CH. Small amounts of r-Culicoides allergens injected into the submandibular lymph nodes with Alum/MPLA as adjuvants seem to induce a suitable immune response for both preventive and therapeutic AIT. The next years will reveal whether these recent advancements will translate into an improved diagnosis, treatment and prevention of CH.     

QUANTITATIVE CONTRAST HARMONIC ULTRASOUND IMAGING OF NORMAL CANINE LIVER

Eight adult dogs with no evidence of liver disease, weighing between 8 and 25 kg were imaged after injection of a microbubble contrast medium using harmonic ultrasound imaging. All dogs received three separate bolus contrast injections, and six dogs also received three separate constant rate infusions each. Time/Mean Pixel Value curves were generated for selected regions of the liver. Upslope, downslope, baseline, peak, change, and time to peak were calculated. For bolus injection (averaging all subjects), upslope was 3.85 +/- 1.50 Mean Pixel Values/s, downslope was -0.71 +/- 0.30 Mean Pixel Values/s, baseline was 72.38 +/- 17.82 Mean Pixel Values, peak was 120.26 +/- 17.44 Mean Pixel Value, change from baseline to peak was 47.88 +/- 6.92 Mean Pixel Values, time to peak (from injection) was 22.88 +/- 6.79 s, and time to peak (from first upslope) was 13.88 +/- 1.55 s. Data acquisition and analysis from constant rate infusions was more cumbersome than for bolus, and results were less repeatable. There were significant differences (p < .005) in upslope, downslope, peak values, and time to peak between the two methods. These baseline data may prove useful in the evaluation of dogs with diffuse hepatic disease.     

Interface structure and atomic bonding characteristics in silicon nitride ceramics

Direct atomic resolution images have been obtained that illustrate how a range of rare-earth atoms bond to the interface between the intergranular phase and the matrix grains in an advanced silicon nitride ceramic. It has been found that each rare-earth atom bonds to the interface at a different location, depending on atom size, electronic configuration, and the presence of oxygen at the interface. This is the key factor to understanding the origin of the mechanical properties in these ceramics and will enable precise tailoring in the future to critically improve the materials' performance in wide-ranging applications.