COMPARATIVE SURVIVAL AND DECOMPOSING ABILITY OF FOUR FUNGI ISOLATED FROM LEAF LITTER AT LOW TEMPERATURES

1974 ◽  
Vol 54 (3) ◽  
pp. 245-253 ◽  
Author(s):  
K. C. IVARSON
Keyword(s):  
Leaf Litter ◽  
Low Temperatures ◽  
Room Temperature ◽  
Abundant Species ◽  
Decomposition Process ◽  
The Other ◽  
Natural Conditions ◽  
Cold Temperatures ◽  
Available Energy ◽  
Cold Tolerant

The survival and decomposing ability of the four dominant fungi found in low-temperature decomposing leaf litter was studied over a 46-mo period, at temperatures ranging from 1 C to room temperature. A Rhizoctonia sp. by itself and in association with the three other fungi disappeared. When alone it brought about no decomposition. Over the temperature range a Penicillium sp. that appeared to be a member of the Penicillium terrestre series showed strong survival properties in association with the other fungi, and by itself decomposed about the same amount of litter as the natural microbial flora of the unaltered litter, indicating that under natural conditions and at temperatures above 1 C this fungus is an important colonizer and decomposer of organic matter. Mucor spinescens alone and in association survived at room temperature and 10 C, but was absent at 4 and 1 C. By itself it decomposed a small amount of litter. The most abundant species, Chrysosporium pannorum (50% of all isolates at cold temperatures), a cellulolytic fungus, was not able to survive in litter in the absence of the other fungi. In their presence, it not only survived but increased in number as temperature decreased. The facts that pH changes and litter extract did not affect its growth suggest that C. pannorum does not possess the ability to be a pioneer colonist, and it is only after associated fungi begin the initial breakdown and perhaps supply easily available energy sources or growth factors that C. pannorum is able to take part in the decomposition process and survive. Thus, as temperature decreases, there is perhaps less competition for this cold-tolerant fungus, and its role in the decomposition process increases.

scholarly journals The principal magnetic susceptibilities of neodymium sulphate octahydrate at low temperatures

1939 ◽  
Vol 170 (941) ◽  
pp. 266-271 ◽  
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Energy Levels ◽  
Constant Factor ◽  
The Other ◽  
Crystalline Field ◽  
Cubic Symmetry ◽  
The Subject ◽  
The Difference ◽  
The One

The magnetic and other related properties of neodymium sulphate have been the subject of numerous investigations in recent years, but there is still a remarkable conflict of evidence on all the essential points. The two available determinations of the susceptibility of the powdered salt at low temperatures, those of Gorter and de Haas (1931) from 290 to 14° K and of Selwood (1933) from 343 to 83° K both fit the expression X ( T + 45) = constant over the range of temperature common to both, but the constants are not the same and the susceptibilities at room temperature differ by 11%. The fact that the two sets of results can be converted the one into the other by multiplying throughout by a constant factor suggested that the difference in the observed susceptibilities was due to some error of calibration. It could, however, also be due to the different purity of the samples examined though the explanation of the occurrence of the constant factor is then by no means obvious. From their analysis of the absorption spectrum of crystals of neodymium sulphate octahydrate Spedding and others (1937) conclude that the crystalline field around the Nd+++ ion is predominantly cubic in character since they find three energy levels at 0, 77 and 260 cm. -1 .* Calculations of the susceptibility from these levels reproduce Selwood’s value at room temperature but give no agreement with the observations-at other temperatures. On the other hand, Penney and Schlapp (1932) have shown that Gorter and de Haas’s results fit well on the curve calculated for a crystalline field of cubic symmetry and such a strength that the resultant three levels lie at 0, 238 and 834 cm. -1 , an overall spacing almost three times as great as Spedding’s.

scholarly journals EFFECT OF FREEZING ON THE FREE AMINO ACIDS IN SOIL

1966 ◽  
Vol 46 (2) ◽  
pp. 115-120 ◽  
Author(s):  
K. C. Ivarson ◽  
F. J. Sowden
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Room Temperature ◽  
Amino Acid Content ◽  
Soil Freezing ◽  
Prolonged Storage ◽  
Cold Temperatures ◽  
Available Energy ◽  
Decomposition Of Organic Matter

Five soils were subjected to temperatures of 1° and −14 °C for 3 weeks. Freezing caused a marked increase in the total amount of free amino acids extracted. The amounts of free amino acids released were greater in soils where decomposition of organic matter was more complete. While prolonged storage of soil at 1 °C had no measurable effect on the free amino acids released, storage over a long period at −14 °C decreased the free amino acid content. Equilibration of wetted soil at room temperature prior to storage at cold temperatures decreased the extractable free amino acids. The data support the contention that part of the effect of soil freezing on the acceleration of microbial activity is due to release of available energy sources.

Enhanced n.m.r. of Cs 2 NaPrCl 6 , Cs 2 NaTbCl 6 and Cs 2 NaTmCl 6

1982 ◽  
Vol 381 (1780) ◽  
pp. 1-16 ◽  
Keyword(s):  
Ground State ◽  
Low Temperatures ◽  
Room Temperature ◽  
Electric Quadrupole ◽  
The Other ◽  
Electric Quadrupole Interaction ◽  
Cubic Field ◽  
Singlet States ◽  
First Excited State ◽  
Cubic Structure

Elpasolite compounds with the formula Cs 2 NaLnCl 6 , where Ln is a lantha­nide ion, have the cubic structure Fm3m (O 5 h ) at room temperature, but some compounds (La, Ce, Pr, Nd) are known to have phase transitions at temperatures between 100 and 160 K to a lower symmetry (Anistratov et al . 1978, Nevald et al . 1979). On the other hand, Cs 2 NaHoCl 6 remains cubic at least down to 0.6 K (Bleaney et al . 1981 a ), although its ground state is a Γ 3 doublet. The compounds of the non-Kramers ions Pr 3+ , Tb 3+ , Tm 3+ have singlet states Γ 1 and we have investigated the enhanced n. m. r. spectra at low temperatures of 141 Pr ( I = 5/2), 159 Tb ( I = 3/2) and 169 Tm ( I = 1/2). The results are interpreted in terms of a predominantly cubic field with a small tetragonal distortion which splits the first excited state, the triplet Γ 4 . The magnitude of this splitting and its sign are consistent with a small elongation along the tetragonal axis for Cs 2 NaPrCl 6 . A novel feature is that the sign of the nuclear electric quadrupole interaction for Pr can be deduced from variations in the line width, ascribed to small, linked variations in the values of P and γ .

The Rate of Movement of Planaria alpina

1935 ◽  
Vol 12 (3) ◽  
pp. 271-285
Author(s):  
R. S. A. BEAUCHAMP
Keyword(s):  
Low Temperatures ◽  
Muscular Contraction ◽  
The Other ◽  
Normal Rate ◽  
Effect Of Temperature ◽  
Inhibitory Process ◽  
Natural Conditions ◽  
Anterior Border ◽  
External Stimuli ◽  
Rate Of Movement

1. The rate of movement and the length of the periods of activity of Pl. alpina are increased by raising the temperature, except at very low temperatures. 2. The normal rate of movement appears to be controlled by a balance between two nervous processes, one being excitatory, the other being inhibitory. 3. The inhibitory process is broken down at the higher temperatures before the excitatory or muscular mechanisms are damaged. 4. Starvation may lead to a slight increase in the rate of movement. 5. External stimuli affect the rate of movement. 6. The chemo-receptors are situated on the extreme anterior border of the head. 7. The effect of temperature on the normal rate of movement gives no information regarding the chemical reactions responsible for muscular contraction. 8. Pl. alpina cannot tolerate indefinitely temperatures higher than 12° C. 9. Under natural conditions Pl. alpina is never found at temperatures above 15° C

Effect of Sodium Exposure On the Mechanical Properties of Zirconium

CORROSION ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 31t-34t ◽  
Author(s):  
J. C. BOKROS
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Tensile Properties ◽  
High Temperatures ◽  
Low Temperatures ◽  
Hydrogen Absorption ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Surface Oxide ◽  
The Other

Abstract It was found that surface oxide which developed on zirconium in impure sodium significantly lowered the fatigue life at elevated temperatures. Hydrogen absorption, on the other hand, had little effect on the fatigue life at elevated temperatures but lowered the fatigue life at room temperature. Also, critical recrystallization which occurred above 950 F in zirconium (a phenomenon unrelated to the presence of sodium) reduced the fatigue life at elevated as well as low temperatures. The effects attributable to sodium (i.e., the formation of surface oxide and absorption of reasonable amounts of hydrogen), did not significantly alter the tensile properties of zirconium at high temperatures. 6.3.20, 4.7, 3.5.8, 3.2.3

Colonization of the Krakatau Islands by Psocoptera (Insecta)

1988 ◽  
Vol 322 (1211) ◽  
pp. 427-443 ◽  
Keyword(s):  
Leaf Litter ◽  
Secondary Forest ◽  
Abundant Species ◽  
The Other ◽  
Diverse Families ◽  
Progressive Development ◽  
Vegetational Succession ◽  
Forest Habitats ◽  
Colonizing Ability ◽  
Faunal Similarity

Eighty species of Psocoptera, of 15 families, were collected on the four Krakatau islands in 1982—86, about a century after the 1883 eruption of Krakatau. The most abundant species on the Krakataus (in the families Lepidopsocidae, Ectopsocidae and Peripsocidae, which are also three of the four most diverse families on the Krakatau group) are typical early colonizing forms, but several ecologically more specialized taxa are also present, and some are limited to particular kinds of vegetation. Families characteristic of forest habitats, Pseudocaeciliidae, Myopsocidae and Psocidae, are poorly represented on the Krakataus. The faunas of Rakata and Panjang are markedly more diverse than those known for Sertung or Anak Krakatau, and the first pair of islands, the only one of the six possible pairs to consist wholly of mixed secondary forest, show the greatest faunal similarity. By reference to the presumed source faunas, there is evidence that the most diverse family on the Krakataus, Caeciliidae, (18 species present) is typical of the order as a whole in colonizing ability, whereas the Lepidopsocidae (11), Ectopsocidae (13) and Peripsocidae (11) are relatively good colonizers, and the Pseudocaeciliidae (3), Myopsocidae (2) and Psocidae (4) relatively poor ones. Within the archipelago, the same trends are apparent for the colonization of the young island of Anak Krakatau, which emerged from the sea in 1930. Taking the three other Krakatau islands as the source, the Caeciliidae again show average colonizing ability, and Lepidopsocidae and Ectopsocidae again are relatively good colonizers. The Peripsocidae, however, show up as rather poorer ones in this model. Because species of this family are predominantly bark dwellers their habitat would not be available as early as that for species of the other families, which are found largely on leaf litter and on living leaves. Progressive development of the psocopteran fauna of the archipelago is discussed in relation to vegetational succession.

ASCORBIC ACID AND ACCLIMATIZATION TO COLD ENVIRONMENT

1947 ◽  
Vol 25e (3) ◽  
pp. 111-136 ◽  
Author(s):  
Louis-Paul Dugal ◽  
Mercedes Thérien
Keyword(s):  
Ascorbic Acid ◽  
Acid Content ◽  
Low Temperatures ◽  
Guinea Pigs ◽  
Room Temperature ◽  
Prolonged Exposure ◽  
Ascorbic Acid Content ◽  
The Other ◽  
Cold Environment ◽  
Direct Relation

A large increase in the ascorbic acid content has been shown to occur in the tissues of the white rat (able to synthesize that vitamin) after prolonged exposure and adaptation to cold (+ 4° to − 4 °C.). The increase in ascorbic acid is much smaller if the rats exposed to low temperatures receive daily supplements of that vitamin. On the other hand, a decrease in ascorbic acid content of the tissues has been found in rats unable to adjust themselves to cold environment. From the above results obtained with the white rat, it seems that the acclimatization to low temperatures—and not only maintenance of life at the same temperatures—requires large quantities of ascorbic acid.That conclusion was confirmed by experiments with guinea-pigs (animals that do not synthesize ascorbic acid); the results obtained show that resistance and adaptation of the guinea-pig to cold environment depend on the amount of ascorbic acid received daily; besides, during the process of acclimatization to cold, more ascorbic acid is retained in the tissues of the guinea-pigs exposed to low temperatures than in the same tissues of control animals kept at room temperature; finally, a direct relation has been observed between adaptability to cold environment and the content of ascorbic acid in the adrenals.

Studies on the bionomics of Trichostrongylus axei (Cobbold) and its seasonal incidence on irrigated pastures

Parasitology ◽  
1938 ◽  
Vol 30 (4) ◽  
pp. 477-490 ◽  
Author(s):  
M. A. Stewart ◽  
J. R. Douglas
Keyword(s):  
Low Temperatures ◽  
Copper Sulphate ◽  
Room Temperature ◽  
Dry Season ◽  
Atmospheric Humidity ◽  
Natural Conditions ◽  
Seasonal Incidence ◽  
Copper Sulphate Solution ◽  
Infective Larvae ◽  
Relative Atmospheric Humidity

1. T. axei eggs in sheep faeces hatch at a temperature of 38° C. and a relative atmospheric humidity of 29%, but all of the larvae are dead 96 hr. after the initiation of the exposure. Eggs kept in faeces at −7° C. are killed within 96 hr.2. Eggs do not hatch while under water but remain viable for 20 days under 15 mm. of water at temperatures ranging from 11 to 28° C. Under natural conditions the longevity would in all probability be influenced by such factors as depth of water, amount of decomposing organic debris, etc., which determine the amount of available oxygen present.3. Completely embryonated eggs in sheep faeces possess a high resistance to drying. It is apparent that ranges and pastures in California cannot be freed of eggs by keeping suitable hosts off them during a single dry season, because the eggs can survive desiccation for a period exceeding the dry season. It is possible, however, that if the eggs were directly exposed to the rays of the sun they might be killed.4. The non-infective larvae of T. axei are very much less resistant to desiccation than are the eggs. The population of non-infective larvae would, however, under the more common natural conditions, normally attain the infective stage before succumbing to desiccation.5. Infective larvae lived for more than 104 days at a temperature of 38° C. and a relative atmospheric humidity of 29%. At −7° C. they were alive at the end of 25 days but were dead on the thirty-ninth day. It is believed that under natural conditions such larvae would not be exterminated by high temperatures. At low temperatures the usual covering of snow might sufficiently protective to prevent death.6. T. axei infective larvae survived 230 days' submergence in 5 mm. of water at room temperature in diffused daylight. Direct sunlight appears have some lethal effect. The amount of oxygen available in the water appears to determine to a considerable degree the longevity of the larvae. Under natural conditions infective larvae can survive even greatly prolonged flooding.7. The survival of infective larvae to desiccation is dependent upon the actual degree of dryness attained. Larvae dried on glass slides at room temperature ranging from 17 to 27° C. with a relative atmospheric humidity of from 35 to 51% survived up to 16 days after the initiation of exposure.8. Different investigators have obtained different results in studying the longevity of infective larvae in soil. The writers believe that the infective larvae do not spend much time on soil or migrate through it unless to escape some unfavourable environmental factor such as particularly high or low temperatures or desiccation, or unless they are accidentally washed into it during heavy rainfall.9. No evidence of phototropic behaviour was observed. It is believed that vertical migration up vegetation is caused by a negatively geotropic reaction which may be conditioned or altered at times by stronger external stimuli resulting from extreme temperatures, bright sunlight, low atmospheric humidity, etc.10. It is believed that the seasonal incidence of trichostrongylosis on irrigated ladino clover pastures in California is determined by acquired resistance, age resistance, or both.11. A mixture of a 1% solution of 40% nicotine sulphate and 1% copper sulphate appears to be a more efficient anthelmintic against T. axei than a straight 1% copper sulphate solution. Changing from green feed to hay or rendering hay available along with green feed may possibly have a therapeutic effect. Spontaneous recovery, so far as clinical symptoms are concerned, from an acute trichostrongylosis, without the administration of a drug or changing the diet, seems to be common, if not the rule, in the majority of lambs in an infected band.

Stromatoporoids from the Famennian (Devonian) Wabamun Formation, Normandville oilfield, north–central Alberta, Canada

1988 ◽  
Vol 62 (03) ◽  
pp. 411-419 ◽  
Author(s):  
Colin W. Stearn
Keyword(s):  
Patch Reef ◽  
Abundant Species ◽  
The Other ◽  
North Central ◽  
Biotic Crisis

Stromatoporoids are the principal framebuilding organisms in the patch reef that is part of the reservoir of the Normandville field. The reef is 10 m thick and 1.5 km2in area and demonstrates that stromatoporoids retained their ability to build reefal edifices into Famennian time despite the biotic crisis at the close of Frasnian time. The fauna is dominated by labechiids but includes three non-labechiid species. The most abundant species isStylostroma sinense(Dong) butLabechia palliseriStearn is also common. Both these species are highly variable and are described in terms of multiple phases that occur in a single skeleton. The other species described areClathrostromacf.C. jukkenseYavorsky,Gerronostromasp. (a columnar species), andStromatoporasp. The fauna belongs in Famennian/Strunian assemblage 2 as defined by Stearn et al. (1988).

Electron microscope studies of the plastic deformation of ternary alloys based on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 1120-1120
Author(s):  
R. Haswell ◽  
U. Bangert ◽  
P. Charsley
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
The Other ◽  
Ternary Alloys ◽  
Dislocation Mobility ◽  
Semiconducting Materials ◽  
Micro Indentation

A knowledge of the behaviour of dislocations in semiconducting materials is essential to the understanding of devices which use them . This work is concerned with dislocations in alloys related to the semiconductor GaAs . Previous work on GaAs has shown that microtwinning occurs on one of the <110> rosette arms after indentation in preference to the other . We have shown that the effect of replacing some of the Ga atoms by Al results in microtwinning in both of the rosette arms.In the work to be reported dislocations in specimens of different compositions of Gax Al(1-x) As and Gax In(1-x) As have been studied by using micro indentation on a (001) face at room temperature . A range of electron microscope techniques have been used to investigate the type of dislocations and stacking faults/microtwins in the rosette arms , which are parallel to the [110] and [10] , as a function of composition for both alloys . Under certain conditions microtwinning occurs in both directions . This will be discussed in terms of the dislocation mobility.

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