Effects of Sub-Lethal High Temperature on An Insect, Rhodnius Prolixus (Stål.)

1968 ◽  
Vol 48 (3) ◽  
pp. 465-473
Author(s):  
A. Y. K. OKASHA
Keyword(s):  
Cell Division ◽  
High Temperature ◽  
Mitotic Activity ◽  
High Temperatures ◽  
Critical Period ◽  
Rhodnius Prolixus ◽  
Epidermal Cells ◽  
Complete Development ◽  
Moulting Hormone ◽  
The Brain

1. In Rhodnius larvae, when moulting is delayed under normal temperature conditions by exposure to high temperature directly after feeding, the brain is needed for a period longer than normal to complete development, i.e. the critical period is postponed. 2. This is associated with a delay in the activation of the thoracic glands and in the mitotic activity in the epidermis. 3. It is suggested that high temperature may act directly on the brain thus inhibiting the secretion of its hormone, although other possibilities are also discussed. 4. The process of wound heating at normal and high temperatures is compared. Injury of the integument results in the ‘activation’ of the epidermal cells and their migration towards the wound. Consequently, a zone of sparse cells is formed which persists at high temperature, since cell division in the epidermis is inhibited. 5. The bearing of the inhibition of cell division on the cessation of moulting at high temperature, even in the presence of the moulting hormone, is discussed.

scholarly journals The Thoracic Gland in Rhodnius Prolixus (Hemiptera) and Its Role in Moulting

1952 ◽  
Vol 29 (4) ◽  
pp. 561-570
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Critical Period ◽  
Fat Body ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Diffuse Layer ◽  
Moulting Hormone ◽  
The Brain

The ‘moulting hormone’ in Rhodnius is composite. The factor secreted in the dorsum of the brain activates a gland in the thorax which then produces the factor initiating growth and moulting. Implantation of the thoracic gland will induce moulting in the isolated abdomen; implantation of the brain is effective only if the thorax is intact. This system agrees with that described in Lepidoptera and Diptera and is probably widespread in insects. The thoracic gland in Rhodnius consists of a loose network of very large cells, richly supplied with tracheae, spread as a single diffuse layer over the surface of the inner lobes of the thoracic fat-body. These cells go through a cycle of secretory activity which reaches its peak during the critical period. They break down and disappear within 2 days after the insect becomes adult. The adult Rhodnius is caused to moult by implantation of the thoracic gland from a moulting larva; it is not caused to moult by implantation of the brain.

Memoirs: The Physiology of Ecdysis in Rhodnius Prolixus (Hemiptera). II. Factors controlling Moulting and ‘Metamorphosis’

1934 ◽  
Vol s2-77 (306) ◽  
pp. 191-222
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
Critical Period ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Corpus Allatum ◽  
Whole Process ◽  
Definite Interval ◽  
Moulting Hormone ◽  
Moulting Cycle ◽  
The Brain ◽  
Complete Metamorphosis

The five nymphal stages of Rhodnius prolixus are more or less alike. The adult differs markedly from the nymphs. There are thus two phenomena to be considered: simple moulting and moulting coupled with metamorphosis. 1. Causation of Moulting. Moulting occurs at a definite interval after feeding, only one meal being necessary in each stage. There is a ‘critical period’ in the moulting cycle (about 7 days after feeding in the fifth nymph, about 4 days in the earlier nymphs) and removal of the head of the insect before this period prevents moulting. The critical period corresponds with the time when mitotic divisions in the epidermis begin. The blood of insects that have passed the critical period contains a factor or hormone which will induce moulting in insects decapitated soon after feeding. It is suggested that this moulting hormone may be secreted by the corpus allatum, since the cells of this gland show signs of greatest secretory activity during the critical period. Stretching of the abdominal wall provides the stimulus which causes secretion of the moulting hormone. This stimulus is conveyed by nerves to the brain: moulting is prevented by section of the nerve-cord in the prothorax. Section of the nerves between the brain and the corpus allatum appears to prevent moulting; but these experiments were inconclusive. Insects sharing the same blood moult simultaneously. The whole process of growth must therefore be co-ordinated by chemical means; the factors concerned being produced presumably by the growing cells themselves. 2. Causation of Metamorphosis. If fourth or even first nymphs, decapitated soon after feeding, receive the blood from moulting fifth nymphs, they suffer a precocious metamorphosis and develop adult characters. Metamorphosis is therefore brought about by chemical differences in the blood. If fifth nymphs decapitated soon after feeding receive blood from moulting fourth nymphs, they also moult; showing that the moulting factor is the same at all stages. The absence of metamorphosis in normal nymphs before the fifth stage must therefore be due to an inhibitory factor or hormone in the blood. This is proved by the fact that if a fifth nymph decapitated soon after feeding receives the blood from a moulting fourth nymph (not deprived of its head) it develops characters much more like those of a nymph than an adult. The inhibitory hormone is normally produced in such small quantities that simple dilution of the blood of a moulting fourth nymph with that of another fourth nymph (decapitated soon after feeding) causes them both to suffer metamorphosis. The head is necessary for the secretion of the inhibitory hormone. This hormone seems to be secreted after the moulting hormone. Thus if series of fourth, third, second, or first nymphs are decapitated around the critical period, some of them show more or less complete metamorphosis. Others show characters intermediate between those of nymphs and adults. The bearing of these results on the phenomena of diapause and prothetely is discussed.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

NICROFER 5520 Co

Alloy Digest ◽  
1995 ◽  
Vol 44 (3) ◽  
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Temperatures ◽  
Heat Treating ◽  
High Temperature Corrosion ◽  
Creep Properties ◽  
Nickel Chromium ◽  
Temperature Performance

Abstract NICROFER 5520 Co is a nickel-chromium-cobalt-molybdenum alloy with excellent strength and creep properties up to high temperatures. Due to its balanced chemical composition the alloy shows outstanding resistance to high temperature corrosion in the form of oxidation and carburization. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ni-480. Producer or source: VDM Technologies Corporation.

CARLSON ALLOY C601

Alloy Digest ◽  
1994 ◽  
Vol 43 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
High Temperatures ◽  
Stress Corrosion Cracking ◽  
Heat Treating ◽  
Resistance To Stress ◽  
Extended Exposure ◽  
Sulfur Containing

Abstract Carlson Alloy C601 is characterized by high tensile, yield and creep-rupture strengths for high temperature service. The alloy is not embrittled by extended exposure to high temperatures and has excellent resistance to stress-corrosion cracking, to carburizing, nitriding and sulfur containing environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, and joining. Filing Code: Ni-458. Producer or source: G.O. Carlson Inc.

INCOTHERM TD

Alloy Digest ◽  
2005 ◽  
Vol 54 (11) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Rare Earths ◽  
Temperature Performance

Abstract Incotherm TD is a thermocouple-sheathing alloy with elements of silicon and rare earths to enhance oxidation resistance at high temperatures. This datasheet provides information on composition, physical properties, and tensile properties as well as deformation. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-628. Producer or source: Special Metals Corporation.

HASTELLOY ALLOY X

Alloy Digest ◽  
1954 ◽  
Vol 3 (12) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Heat Treating ◽  
Operating Conditions ◽  
Molybdenum Alloy ◽  
High Temperature Strength ◽  
Nickel Chromium

Abstract HASTELLOY Alloy X is a nickel-chromium-iron-molybdenum alloy recommended for high-temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on forming, heat treating, and machining. Filing Code: Ni-14. Producer or source: Haynes Stellite Company.

KUBOTA ALLOY HT

Alloy Digest ◽  
2011 ◽  
Vol 60 (11) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Nickel Alloy ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Temperature Performance ◽  
Iron Chromium

Abstract Kubota Alloy HT is an iron-chromium-nickel alloy that has both strength and oxidation resistance at high temperatures. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: SS-1108. Producer or source: Kubota Metal Corporation, Fahramet Division.

KENTANIUM K138A

Alloy Digest ◽  
1964 ◽  
Vol 13 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
High Temperature ◽  
Titanium Carbide ◽  
Physical Properties ◽  
Engineering Design ◽  
High Temperatures

Abstract Kentanium K138-A is a high temperature titanium carbide that greatly widens the scope of the engineering design where conditions of intermittent or continuous high temperatures in oxidizing atmospheres are combined with abrasion, and compressive or tensile loads. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength as well as fracture toughness, creep, and fatigue. It also includes information on machining and joining. Filing Code: Ti-40. Producer or source: Kennametal Inc..

RA 309

Alloy Digest ◽  
1963 ◽  
Vol 12 (4) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Temperatures ◽  
Heat Treating ◽  
Corrosion Resistant Steel ◽  
Resistant Steel ◽  
Corrosion Resistant ◽  
Temperature Performance

Abstract RA 309 is a chromium-nickel heat and corrosion resistant steel recommended for high temperatures applications. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-142. Producer or source: Rolled Alloys Inc..

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