scholarly journals Is the initial nest depth adapted to favorable conditions for the incipient colony in leaf-cutting ants?

Sociobiology ◽  
2016 ◽  
Vol 63 (2) ◽  
pp. 792 ◽  
Author(s):  
Roberto Camargo ◽  
Luiz Carlos Forti ◽  
Carlos Alberto Oliveira Matos ◽  
Nadia Caldato ◽  
Otavio Silvaston Fonseca
Keyword(s):  
Lipid Content ◽  
Colony Development ◽  
Atta Sexdens ◽  
Brood Production ◽  
Symbiotic Fungus ◽  
Temperature Range ◽  
Different Temperatures ◽  
Nest Depth ◽  
Incipient Colony ◽  
Favorable Conditions

The nest dug by the leaf-cutter ant queen of the genus Atta is a vertical tunnel interconnected to a small chamber to hold its offspring and the symbiotic fungus. The depth of the initial chamber of the Atta sexdens rubropilosa ranges from 10 to 30 cm below the soil surface. This available information, could it be that the ideal initial nest depth is adapted to favorable conditions for the initial colony? We hypothesized this depth can provide a minimum temperature range with almost constant temperature, leading to the development of symbiotic fungus and brood yet to emerge. To test this hypothesis, laboratory experiments were carried out and the soil temperature was measured at different depths. The colony development at different temperatures was studied in the laboratory and the brood production (number of eggs, larvae, pupae and adults) was measured until the first workers emergency. Additionally, lipid content and the survival of queens at different temperatures were determined. Our results show an suitable temperature range (ranging from 24.82±3.14°C to 24.11±1.30°C) at a depth of 5 to 25 cm from the ground, an ideal brood development at temperatures of 24 and 28 °C, and consequently a reduction in lipid content of the queens at high temperatures, without affecting their survival in the trial period. These results indicate that the depth of the initial chamber excavated by the queen is suitable for the success of the incipient colony.

The Design of AlGaN/GaN HEFT-Micro-Accelerometer and Temperature- Dependence Electrical Performance

2011 ◽  
Vol 483 ◽  
pp. 174-179 ◽  
Author(s):  
Ting Liang ◽  
Jian Jun Tang ◽  
Qian Qian Zhang ◽  
Yong Wang ◽  
Jing Li ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Electrical Performance ◽  
Saturation Current ◽  
Temperature Range ◽  
Different Temperatures ◽  
Piezoresistance Coefficient ◽  
Micro Accelerometer

In this paper, We use a novel principle to detect acceleration and report how I-V characteristics and piezoresistance coefficient of AlGaN/GaN HEFT-micro-accelerometer are affected by setting different temperatures. It is shown that saturation current of device would go down if the temperature goes up, which is about 0.028mA/°C, based on the research. However, the device can work well at the temperature range of -50°C to 50°C, which indicates that it can work safely in the larger temperature range.

scholarly journals A Study on the Effect of Ultrasonic Treatment on the Microstructure of Sn-30 wt.% Bi Alloy

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1870
Author(s):  
Shuo Wang ◽  
Jinwu Kang ◽  
Xiaopeng Zhang ◽  
Zhipeng Guo
Keyword(s):  
Ultrasonic Treatment ◽  
Acoustic Streaming ◽  
Eutectic Structure ◽  
Eutectic Phase ◽  
Ultrasonic Cavitation ◽  
Mixed Effect ◽  
Temperature Range ◽  
Different Temperatures

The effect of ultrasonic treatment on the microstructure of Sn-30 wt.% Bi alloy was studied at different temperatures. Results showed that the ultrasonic treatment could effectively refine the microstructure of Sn-30 wt.% Bi alloy at a temperature range between the liquidus and solidus. Application of the ultrasound could fragment the primary Sn dendrites during solidification due to a mixed effect of ultrasonic cavitation and acoustic streaming. The divorced eutectic formed when the ultrasonic treatment was applied for the whole duration of the solidification. The eutectic phase grew and surrounded the primary Sn dendrite, and pure Bi phase grew in between the Sn dendritic fragments. The mechanism of the fragmentation of dendrites and the divorced eutectic structure by ultrasonic treatment was discussed.

Infectivity of populations of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis in relation to temperature, age and lipid content

Nematology ◽  
2000 ◽  
Vol 2 (5) ◽  
pp. 515-521 ◽  
Author(s):  
Hara Menti ◽  
Denis Wright ◽  
Roland Perry
Keyword(s):  
Lipid Content ◽  
Dose Response ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Steinernema Feltiae ◽  
Optimal Temperature ◽  
Temperature Range ◽  
Heterorhabditis Megidis ◽  
Before And After ◽  
The Uk

AbstractThe infectivity of populations of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis from Greece (GR) and the UK was compared using Galleria mellonella larvae as hosts. Dose-response tests showed that the two Steinernema populations did not differ in their establishment rates but they were more infective than H. megidis UK 211. The temperature range for infectivity was greater than that for development. However, the optimal temperature for infection and development for all populations was 23°C. Infectivity of Steinernema populations was not affected by storage for 12 weeks. However, 12 week-old H. megidis UK 211 infective juveniles (IJ) were less infective than fresh IJ. H. megidis GR showed very low establishment rates at all the doses and temperatures tested, before and after storage. The results are discussed in relation to the nematodes' climatic origin and lipid content. Pouvoir infestant de populations des nématodes entomopathogènes Steinernema feltiae et Heterorhabditis megidis suivant la température, l'âge et le contenu lipidique - Le pouvoir infestant de populations des nématodes entomopathogènes Steinernema feltiae et Heterorhabditis megidis provenant de Grèce et du Royaume Uni a été comparée, utilisant comme hôte Galleria mellonella. Les tests de dose/réaction ont montré que les taux d'établissement des deux populations ne diffèrent pas mais que leur pouvoir infestant était plus élevée que celle de H. megidis UK211. La plage des températures permettant l'infestation était plus étendue que celle relative au développement. Cependant, les températures optimales pour l'infestation et pour le développement étaient l'une et l'autre de 23°C pour toutes les populations. L'infestivité des populations de Steinernema n'a pas été affectée par un stockage de 12 semaines. Les juvéniles infestants de H. megidis UK211 âgés de 12 semaines montraient toutefois une infestivité plus faible que celle d'individus frais. Les specimens de H. megidis provenant de Grèce présentaient - que ce soit avant ou après le stockage - des taux d'établissement très faibles pour toutes les doses et les températures testées. Ces résultats sont discutés en relation avec l'origine climatique et le contenu lipidique des nématodes.

scholarly journals Application of headspace for research volatile organic compounds emitted from building materials

2018 ◽  
Vol 28 ◽  
pp. 01019
Author(s):  
Beata Kultys ◽  
Karolina Waląg
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Building Materials ◽  
Heating Temperature ◽  
Mineral Wool ◽  
Chromatography Method ◽  
Temperature Range ◽  
Volatile Organic ◽  
Different Temperatures

Headspace technique and gas chromatography method with mas detector has been used for the determination of volatile organic compounds (VOC) emitted from various building and finishing materials, such as sealing foams, mounting strips, paints, varnishes, floor coverings. The tests were carried out for different temperatures (in the temperature range of 60 to 180 °C) and the time of heated vials with tested materials inside. These tests were conducted to verify the possibility of use this method of determination the VOC emission. Interpretation of chromatograms and mass spectra allowed to identify the type of compounds emitted from the tested materials and the optimum time and temperature for each type of material was determined. The increase in heating temperature of the samples resulted in increase the type and number of identified compounds: for four materials the increase was in the whole temperature range, for others it was from 90 °C. On the other hand, emission from mineral wool was low in whole temperature range. 30-minutes heating of the samples was sufficient to identify emitted compounds for most of tested materials. Applying a longer time, i.e. 24 hours, significantly increased the sensitivity of the method.

The cracking of cyclo pentene on a silica-alumina catalyst

1960 ◽  
Vol 257 (1288) ◽  
pp. 132-145 ◽  
Keyword(s):  
Molecular Weight ◽  
Catalytic Cracking ◽  
Slow Step ◽  
Static System ◽  
Surface Complexes ◽  
Temperature Range ◽  
Carbonium Ions ◽  
Wide Range ◽  
Different Temperatures ◽  
Silica Alumina

The cracking of cyclo pentene on silica-alumina was studied in a flow system over the temperature range 368 to 505 °C. The analysis of the products was carried out by gas-liquid chromatographic techniques and the design of the apparatus made it possible to measure the pressures of compounds of low molecular weight at a series of points along the catalyst bed. Partial analyses were made of the extremely wide range of products of high molecular weight collected at the end of the reactor for reactions at three different temperatures. The results obtained were sufficiently detailed to provide activation energies for the for­mation of a number of the products and for the decomposition of cyclo pentene and to per­mit the application of thermodynamical calculations to ascertain the source of substances such as cyclo pentane and methyl cyclo pentane. The results of the flow experiments together with a subsidiary experiment on the reactions which occurred to cyclo pentene at 68 °C on the catalyst in a static system indicated that the formation, polymerization and isomerization of the surface complexes to condensed six-membered ring systems must be extremely rapid processes in the temperature range required for the catalytic cracking of cyclo pentene. These processes probably occur through the formation of carbonium ions and consequently the formation of these ions is unlikely to be the slow step in the catalytic cracking of olefins. The rate of the cracking reaction may depend on the rate of decomposition of carbonium ions considerably larger in size than the original olefin.

Studies on the application of the quinhydrone electrode in formamide. IV. The ionization constants and related thermodynamic quantities of picric acid from E.M.F. measurements at different temperatures

1975 ◽  
Vol 28 (4) ◽  
pp. 797 ◽  
Author(s):  
UN Dash ◽  
B Nayak
Keyword(s):  
Picric Acid ◽  
Ionization Constants ◽  
Thermodynamic Quantities ◽  
Temperature Range ◽  
Pka Value ◽  
Different Temperatures

The e.m.f, of the cell ���������������� Ag-AgCl/KCl(m3), KPic(m2), HPic(m1), QH2-Q|Au in formamide has been measured at 5� intervals over the temperature range 5-45�C. The pKa value of picric acid ranges from 2.19 � 0.12 at 5� to 1.16 � 0.08 at 45�.

Methanogenesis in sediments from deep lakes at different temperatures (2–70°C)

1997 ◽  
Vol 36 (6-7) ◽  
pp. 57-64 ◽  
Author(s):  
Alla N. Nozhevnikova ◽  
C. Holliger ◽  
A. Ammann ◽  
A. J. B. Zehnder
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Methane Production ◽  
Low Temperatures ◽  
Main Question ◽  
Deep Lakes ◽  
Temperature Range ◽  
Wide Range ◽  
Thermophilic Conditions ◽  
Different Temperatures

Methanogenic degradation of organic matter occurs in a wide temperature range from psychrophilic to extreme thermophilic conditions. Mesophilic and thermophilic methanogenesis is relatively well investigated, but little is known about low temperature methanogenesis and psychrophilic methanogenic communities. The aim of the present work was to study methanogenesis in a wide range of temperatures with samples from sediments of deep lakes. These sediments may be considered deposits of different types of microorganisms, which are constantly exposed to low temperatures. The main question was how psychrophilic methanogenic microbial communities compare to mesophilic and thermophilic ones. Methanogenesis in a temperature range of 2–70°C was investigated using sediment samples from Baldegger lake (65 m) and Soppen lake (25 m), Switzerland. Methane production from organic matter of sediments occurred at all temperatures tested. An exponential dependence of methane production rate was found between 2 and 30°C. Methanogenesis occurred even at 70°C. At the same time stable methane production from organic matter of sediments was observed at temperatures below 10°C. Methanogenic microbial communities were enriched at different temperatures. The communities enriched at 4–8°C had the highest activity at low temperatures indicating that a specific psychrophilic community exists. Addition of substrates such as cellulose, volatile fatty acids (butyrate, propionate, acetate), methanol and H2/CO2 stimulated methane production at all temperatures. H2/CO2 as well as methanol were directly converted to methane under thermophilic conditions. At low temperatures these substrates were converted to methane by a two-step process. First acetate was formed, followed by methane production from acetate. When acetate concentrations were high, acetoclastic methanogenesis was inhibited at low temperatures. This reaction appears to be one of the “bottle neck” in psychrophilic methanogenesis.

scholarly journals Toxicity of sesame extracts to the symbiotic fungus of leaf-cutting ants

1990 ◽  
Vol 80 (3) ◽  
pp. 349-352 ◽  
Author(s):  
Fernando Carlos Pagnocca ◽  
Osvaldo Aulino da Silva ◽  
Maria Jose Hebling-Beraldo ◽  
Odair Correa Bueno ◽  
João Batista Fernandes ◽  
...  
Keyword(s):  
Sesamum Indicum ◽  
Atta Sexdens ◽  
Symbiotic Fungus ◽  
Atta Sexdens Rubropilosa ◽  
Leaf Cutting ◽  
Leucocoprinus Gongylophorus

AbstractExtracts of different sesame plant (Sesamum indicum) Linnaeus organs inhibited the in vitro growth of the fungus Leucocoprinus gongylophorus (Möller) (=Rozites gongylophora Möller), which is cultivated by the leaf-cutting ants of the species Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae). The presence of the factor responsible for this inhibition was detected in methanol or chloroform extracts and is constant in the plant.

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