Evaluation of a method for quantification of Pythium aphanidermatum in cucumber roots at different temperatures and inoculum densities

2006 ◽  
Vol 113 (3) ◽  
pp. 113-119 ◽  
Author(s):  
M. A. Kyuchukova ◽  
C. Büttner ◽  
J. Gabler ◽  
B. Bar-Yosef ◽  
R. Grosch ◽  
...  
Keyword(s):  
Pythium Aphanidermatum ◽  
Different Temperatures ◽  
Cucumber Roots

Fungi associated with roots of cucumber grown in different greenhouse root substrates

2005 ◽  
Vol 83 (1) ◽  
pp. 80-92 ◽  
Author(s):  
J G Menzies ◽  
D L Ehret ◽  
C Koch ◽  
J W Hall ◽  
K A Seifert ◽  
...  
Keyword(s):  
Root Zone ◽  
Pythium Aphanidermatum ◽  
Common Species ◽  
Penicillium Oxalicum ◽  
Trichoderma Spp ◽  
Pythium Irregulare ◽  
Penicillium Janthinellum ◽  
Cucumber Seedlings ◽  
Root Diseases ◽  
Cucumber Roots

Hydroponic soilless culture systems are commonly used in the greenhouse industry to mitigate soilborne root pathogens, but root diseases continue to be a major problem. A thorough knowledge of the root zone ecology of greenhouse crops is needed for the successful biological control of root diseases. The objectives of this study were to characterize the fungi associated with symptomless cucumber roots grown using different greenhouse substrates and to determine the effects of these fungi on plant growth. A total of 1250 fungal isolates were collected from cucumber roots grown in soil, rockwool, sawdust, or nutrient film and identified to genus and species. There was a greater density of fungal colonies on roots grown in soil than on roots grown in other substrates. Penicillium (87.2% of all isolates), Trichoderma (4.6%), and Pythium (3.0%) were the most common genera isolated from the cucumber roots. The two most common species were Penicillium oxalicum Currie & Thom (69.9%) and Penicillium janthinellum Biourge(13.4%). Pythium group F, Pythium group G, Pythium aphanidermatum (Edson) Fitzp., and Pythium irregulare Buisman were also isolated from healthy cucumber roots and all except Pythium group F were pathogenic to germinating cucumber seedlings. Treatment of cucumber seeds with Penicillium spp. resulted in significantly greater shoot length, root length, and seedling fresh weight of the resulting cucumber seedlings than did treatment with Trichoderma spp. One isolate of Penicillium janthinellum and one of Aspergillus sp. significantly improved survival of cucumber seedlings growing in a Pythium aphanidermatum-infested medium.Key words: hydroponics, Penicillium, Trichoderma, Pythium, Cucumis sativus.

scholarly journals Differential Suppression of Damping-off Caused by Pythium aphanidermatum, P. irregulare, and P. myriotylum in Composts at Different Temperatures

Plant Disease ◽  
1999 ◽  
Vol 83 (4) ◽  
pp. 356-360 ◽  
Author(s):  
Yephet Ben-Yephet ◽  
Eric B. Nelson
Keyword(s):  
Variable Temperature ◽  
Pythium Aphanidermatum ◽  
Temperature Cycle ◽  
Damping Off ◽  
Temperature Dependent ◽  
Negative Interaction ◽  
Different Temperatures ◽  
Host Origin ◽  
Municipal Biosolids ◽  
Effects Of Temperature

The suppressiveness of compost amendments to pre-emergence damping-off of cucumber incited by isolates of Pythium aphanidermatum, P. myriotylum, and P. irregulare was studied. Growth chamber experiments were designed to examine the effects of temperature (20, 24, 28, and 32°C), compost type (municipal biosolids [MC] and leaves [LC]), and compost dose (40, 80, 160, and 320 mg/cm3) on suppression of damping-off (i.e., increase in seedling stands) caused by different Pythium isolates obtained from different hosts. In dose-response experiments, LC was suppressive at dosage rates ≥80 mg compost/cm3 of sand, whereas MC was suppressive at rates ≥40 mg/cm3. Damping-off severity induced by each of the three Pythium spp. was temperature-dependent. For example, P. aphanidermatum and P. myriotylum caused damping-off at each of the four temperatures tested, whereas P. irregulare caused disease only at 20 and 24°C. MC was suppressive to P. aphanidermatum at 20 and 24°C, whereas LC was suppressive at 28 and 32°C. Both composts significantly suppressed damping-off caused by P. irregulare at 20°C (85% suppression in MC and 60% suppression in LC) and at 24°C (approximately 60% suppression in both composts), and by P. myriotylum at all temperatures tested. In experiments with a variable temperature cycle (32°C for 14 h, day and 22°C for 10 h, night), only P. aphanidermatum and P. myriotylum caused damping-off of cucumber seedlings. Under these conditions, LC significantly suppressed damping-off caused by P. aphanidermatum (20% suppression) or P. myriotylum (37% suppression) but MC was not suppressive. In experiments where the two composts were mixed, a significant negative interaction between the two composts was observed for the suppression of P. myriotylum and P. irregulare at 20°C and of P. irregulare at 24°C, but not for P. aphanidermatum at any of the tested temperatures. There was no difference in aggressiveness among isolates within each of the three Pythium spp., regardless of their host origin. However, a significant variation in suppressiveness of LC was observed among isolates of P. aphanidermatum (11 isolates) derived from the same host, but not for P. irregulare (9 isolates) or P. myriotylum (7 isolates).

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Quantitative Assessment of Soluble Fibrin in Plasma by Affinity Chromatography – A Comparative Study with desAA-Fibrin, desAABB-Fibrin and Fibrinogen

1985 ◽  
Vol 54 (02) ◽  
pp. 533-538 ◽  
Author(s):  
Wilfried Thiel ◽  
Ulrich Delvos ◽  
Gert Müller-Berghaus
Keyword(s):  
Affinity Chromatography ◽  
Calcium Ions ◽  
Quantitative Assessment ◽  
Fluid Phase ◽  
Soluble Fibrin ◽  
Binding Characteristics ◽  
Different Temperatures ◽  
Immobilized Proteins ◽  
Sepharose 4B

SummaryA quantitative determination of soluble fibrin in plasma was carried out by affinity chromatography. For this purpose, desAA-fibrin and fibrinogen immobilized on Sepharose 4B were used at the stationary side whereas batroxobin-induced 125I-desAA-fibrin or thrombin-induced 125I-desAABB-fibrin mixed with plasma containing 131I-fibrinogen represented the fluid phase. The binding characteristics of these mixtures to the immobilized proteins were compared at 20° C and 37° C. Complete binding of both types of fibrin to the immobilized desAA-fibrin was always seen at 20° C as well as at 37° C. However, binding of soluble fibrin was accompanied by substantial binding of fibrinogen that was more pronounced at 20° C. Striking differences depending on the temperature at which the affinity chromatography was carried out, were documented for the fibrinogen-fibrin interaction. At 20° C more than 90% of the applied desAA-fibrin was bound to the immobilized fibrinogen whereas at 37° C only a mean of 17% were retained at the fibrinogen-Sepharose column. An opposite finding with regard to the tested temperature was made with the desAABB-fibrin. Nearly complete binding to insolubilized fibrinogen was found at 37° C (95%) but only 58% of the desAABB-fibrin were bound at 20° C. The binding patterns did not change when the experiments were performed in the presence of calcium ions. The opposite behaviour of the two types of soluble fibrin to immobilized fibrinogen at the different temperatures, together with the substantial binding of fibrinogen in the presence of soluble fibrin to insolubilized fibrin in every setting tested, devaluates affinity chromatography as a tool in the quantitative assessment of soluble fibrin in patients’ plasma.

Heat wave effects on biomass and vegetative growth of macrophytes after long-term adaptation to different temperatures: a mesocosm study

2015 ◽  
Vol 66 (3) ◽  
pp. 265-274 ◽  
Author(s):  
Y Cao ◽  
ÉM Neif ◽  
W Li ◽  
J Coppens ◽  
N Filiz ◽  
...  
Keyword(s):  
Heat Wave ◽  
Vegetative Growth ◽  
Wave Effects ◽  
Different Temperatures

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

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