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  • rhizosphere  (5)
  • 81.20.Lb  (2)
  • Cytochemistry  (2)
  • Springer  (9)
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  • Springer  (9)
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  • 1
    Electronic Resource
    Electronic Resource
    Effects of particle packing on the sintered microstructure (1988)
    Springer
    Applied physics 45 (1988), S. 271-275 
    Details
    ISSN: 1432-0630
    Keywords: 81.20.Ev ; 81.20.Lb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The sintering process is shown to be critically dependent on particle-packing density and porosity uniformity. Sintering experiments were conducted on compacts consisting of monodisperse, spherical TiO2 particles. Densification kinetics and microstructure evolution for two initial packing densities, 55% and 69% of theoretical, were investigated. The lower-density compacts sintered rapidly to theoretical density, yet improved particle-packing density and uniformity significantly enhanced densification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617931
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on the ovotestis of the slug Agriolimax reticulatus (Müller) (1976)
    Springer
    Cell & tissue research 173 (1976), S. 465-482 
    Details
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Cytochemistry ; Oocytes ; Molluscs ; Vitellogenesis ; Nucleoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovarian oocytes of Agriolimax reticulatus (Müller) have been studied by light and electron microscopy and electron cytochemistry. The development of the oocyte in the ovotestis may be divided into three stages. During Stage I the oocyte cytoplasm contains mainly ribosomes and also strands of endoplasmic reticulum, scattered mitochondria and Golgi systems. The nucleus contains both a paranucleolus and an eunucleolus. By Stage II the oocyte has enlarged, especially in a plane parallel to the basement membrane. In addition to the above mentioned organelles, the cytoplasm contains lipid, glycogen and early yolk platelets. During Stage III, the oocyte continues to enlarge, but mainly in a plane perpendicular to the basement membrane. A considerable degree of cytoplasmic differentiation has also taken place. The plasma membrane of the oocyte has become specialized with the appearance of a polysaccharide-rich glycocalyx, microvilli and pinocytotic tubules. Elsewhere, much of the background cytoplasm, containing Golgi-derived, polysaccharide and acid phosphatase-rich multivesiculate bodies, lipid and glycogen, is sequestered by smooth membranes and ultimately fuses with the growing yolk platelets. The nucleus contains an amphinucleolus, characteristic of many gastropods. The findings of this study are discussed in relation to results from other studies on oogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224309
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of starvation on the planarian worm Polycelis tenuis iijima (1976)
    Springer
    Cell & tissue research 169 (1976), S. 193-209 
    Details
    ISSN: 1432-0878
    Keywords: Planaria ; Starvation ; Fine structure ; Biochemistry ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Employing a combination of microscopical, biochemical and autoradiographic techniques, the primary effects of starvation on adult Polycelis tenuis have been studied. Over a five week period of starvation there is on average a 32% decrease in the size of the organism. This decrease is contributed to by a reduction in mitosis and an increase in cell shrinkage autolysis and death. During starvation (following a sharp rise in RNA synthesis) there is a distinct sequence of events; four peaks of acid phosphatase activity can be resolved. The first is associated with the immediate response of the gastrodermis to feeding; the second (after 6 to 7 days) with increased autophagy and dedifferentiation in the gland cells and with muscle lysis; the third peak (after 14 to 15 days) is contributed to largely by the lysis of cells in the gut and the fourth peak (after 25 to 26 days) is caused by an extensive lysis of the reproductive system. Fine structural changes involving increased intracellular vacuolation, autophagy, crinophagy, atrophy of muscle, increased intercellular space and loss of basement membrane matrix have been related to changes in enzyme pattern. Nerve cells appear unchanged throughout the first five weeks of starvation. Pigment and gland cells loose their characteristic granules, dedifferentiate and become morphologically similar to the undifferentiated neoblasts. Dedifferentiation and the mechanisms involved in the survival of starvation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214208
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  • 4
    Electronic Resource
    Electronic Resource
    Intra-specific variation in growth and P accumulation of Leucaena leucocephala and Gliricidia sepium as influenced by soil phosphate status (1991)
    Springer
    Plant and soil 133 (1991), S. 201-208 
    Details
    ISSN: 1573-5036
    Keywords: isolines ; nodulation ; N2 fixation ; P uptake ; P use efficiency ; provenances ; Rhizobium ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Twenty-three provenances of Gliricidia sepium and eleven isolines of Leucaena leucocephala were examined at a low and at high phosphate levels (20 and 80 mg P kg-1 soil) for growth, phosphate (P) uptake and use efficiency. Large differences in growth at the low P level, and in growth response to the higher P rate occurred among L. leucocephala isolines and G. sepium provenances. Shoot dry weight at low P varied from 1.30 to 3.01 g plant-1 for L. leucocephala and from 1.44 to 3.07 g plant-1 for G. sepium. Leucaena isolines had only half the root weight of G. sepium provenances yet produced approximately 90% of the shoot weight of the corresponding G. sepium treatments, i.e. more than a 2-fold difference in root/shoot ratios. Total P in shoots of G. sepium was some 85% greater than of the respective L. leucocephala isolines in corresponding treatments. Physiological phosphate use efficiency (g shoot/mg P in shoots) (PPUE) was not a simple reciprocal relation, being markedly lower at higher shoot % P and content. However, for the same shoot P both species produced the same shoot weight. Nevertheless, there were apparent genotypic differences within species in the root development, shoot P and PPUE. In another study, the numbers of rhizobia in the rhizosphere of L. leucocephala, nodulation, N2 fixation at five different levels of P were determined. The numbers of rhizobia in the rhizosphere of inoculated L. leucocephala during the first two weeks were lower when P was added but later became similar to those without added P. Nodules formed earlier than inoculated plants fertilized with P and in greater numbers (4- to 5-fold) and dry weights than in those without P. However, the percentage of N2 derived from fixation did not change with increasing levels of P application. These results suggest that the observed P effect did not operate via stimulated growth of rhizobia in the rhizosphere, nor through increased N2 fixation rate. The major effect appeared to be due to effects via plant growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009192
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of selected geocarposphere bacteria for biological control of Aspergillus flavus in peanut (1995)
    Springer
    Plant and soil 175 (1995), S. 291-299 
    Details
    ISSN: 1573-5036
    Keywords: Arachis hypogaea ; Aspergillus flavus ; biological control ; geocarposphere ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Selected bacterial strains isolated from the region of peanut pod development (geocarposphere) and two additional bacterial strains were screened as potential biological control agents against Aspergillus flavus invasion and subsequent aflatoxin contamination of peanut in laboratory, greenhouse, and field trials. All 17 geocarposphere strains tested delayed invasion of young roots and reduced colonization by the fungus in a root-radicle assay used as a rapid laboratory prescreen. In a greenhouse study, seven bacterial strains significantly reduced pod colonization by A. flavus compared to the control. In a field trial, conducted similarly to the greenhouse assay, pods sampled at mid-peg from plants seed-treated with suspensions of either 91A-539 or 91A-550 were not colonized by A. flavus, and the incidence of pods invaded from plants treated with either 91A-539 or 91A-599 was consistently lower than nonbacterized plants at each of five sampling dates. At harvest, 8 geocarposphere bacterial strains significantly lowered the percentage of pods colonized (〉 51%) compared to the control. Levels of seed colonization ranged from 1.3% to 45% and did not appear related to aflatoxin concentrations in the kernels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011365
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  • 6
    Electronic Resource
    Electronic Resource
    Quantification of the geocarposphere and rhizosphere effect of peanut (Arachis hypogaea L.) (1991)
    Springer
    Plant and soil 136 (1991), S. 103-109 
    Details
    ISSN: 1573-5036
    Keywords: Archis hypogaea ; Aspergillus flavus ; geocarposphere ; groundnut ; peanut ; Pseudomonas ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots and pods of field-grown peanut (groundnut) (Arachis hypogaea L.) were sampled at the R3, R5, and R7 developmental stages and examined in comparison to root- and pod-free soil for microbial population densities to assess the geocarposphere and rhizosphere effects. G/ S (no. geocarposphere microorganisms/no. soil microorganisms) and R/S (no. rhizosphere microorganisms/no. soil microorganisms) ratios were calculated for total fungi,Asperigillus flavus, spore-forming bacilli, coryneform bacteria, fluorescent pseudomonads, and total bacteria isolated on low- and high-nutrient media. A clear geocarposphere effect was evidenced by increased population densities of bacteria and fungi associated with developing pods compared to soil. G/S and R/S ratios were generally greater than 1.0 for all groups of microorganisms except bacilli. G/S ratios were greater for total bacteria than for total fungi at two of the three sample times, suggesting that bacteria were stimulated more than fungi in the zone around developing pods. In contrast, R/S ratios, were higher for total fungi than for total bacteria at two of three sample times. The preferential association of fungi and bacteria with early developmental stages of the pod indicates that some microorganisms are particularly well adapted for colonization of the peanut geocarposphere. These microorganisms are logical candidates for evaluation as biological control candiates forA. flavus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02465225
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative identification by fatty acid analysis of soil, rhizosphere, and geocarposphere bacteria of peanut (Arachis hypogaea L.) (1992)
    Springer
    Plant and soil 139 (1992), S. 85-90 
    Details
    ISSN: 1573-5036
    Keywords: Arachis hypogaea ; Aspergillus flavus ; geocarposphere ; groundnut ; peanut ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bacterial isolates were collected from the geocarposphere, rhizosphere, and root-free soil of field grown peanut (Arachis hypogaea L.) at three sample dates, and the isolates were identified by analysis of fatty acid methyl-esters to determine if qualitative differences exist among the bacterial microflora of these zones. Five bacterial genera were associated with isolates from soil, while pod and root isolates constituted 16 and 13 genera, respectively, indicating that bacterial diversity was higher in the rhizosphere and geocarposphere than in soil. The dominant (most frequently identified) genus across all three samples dates was Flavobacterium, for pods, Pseudomonas for roots, and Bacillus, for root-free soil. Sixteen bacterial taxa were only isolated from the geocarposphere, 7 only from the rhizosphere, and 5 only from soil. These results show that specific bacterial taxa are preferentially adapted to colonization of the geocarposphere and suggest that the soil, rhizosphere, and geocarposphere constitute three distinct ecological niches. Bacteria which colonize the geocarposphere should be examined as potential biological control agents for pod-invading fungi such as the toxigenic strains of Aspergillus flavus and A. parasiticus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012845
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  • 8
    Electronic Resource
    Electronic Resource
    The ecology of ectomycorrhiza formation and functioning (1994)
    Springer
    Plant and soil 159 (1994), S. 61-67 
    Details
    ISSN: 1573-5036
    Keywords: basidiospores ; fungus succession ; infection dynamics ; mycelial growth ; mycelial strands ; mycorrhizal responses ; rhizosphere ; sclerotia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Factors in inoculum potential/infection levels/plant growth response are analysed and experimental approaches to propagule germination, growth through soil and rhizosphere growth are indicated. It is suggested that seedling rhizosphere germination of basidiospores occurs particularly with early stage fungi, while late stage fungi may be advantaged by germination/growth on exudates from older parts of roots or on litter (and its associated microorganisms) and their tolerance of antimicrobial substances in litter. Relative growth in the rhizosphere is likely to dominate the mycorrhizal species composition and this may be a good selection method for organisms tolerant of stress and pollution conditions. As mycorrhizal function in nutrient uptake is largely determined by fungus growth into soil, there is need for much more experimental study of factors affecting this, and of the potential photosynthate drain this could represent. The possibility of selection/breeding mycorrhizal fungi with both ‘early stage’ and ‘late stage’ attributes is raised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000095
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  • 9
    Electronic Resource
    Electronic Resource
    An investigation of catalytic activity in mixed metal oxide nanophase materials (1993)
    Springer
    The European physical journal 26 (1993), S. 46-50 
    Details
    ISSN: 1434-6079
    Keywords: 82.65.Jv ; 81.20.Lb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present preliminary evidence for catalytic activity by unsupported mixed metal oxide nanocrystalline materials. The results of this study show that a nanophase form of Li-MgO has begun to exhibit catalytic activity by 300 °C. This is at least 200 degrees below the temperature at which conventional Li-MgO catalysts exhibit comparable activity. Furthermore, at higher temperatures, the same nanophase composition shows enhanced activities and somewhat improved hydrocarbon selectivities over conventional Li-MgO catalysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01429104
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