scholarly journals An electric furnace for experiments in vacuo at temperatures

1912 ◽  
Vol 87 (598) ◽  
pp. 519-524
Keyword(s):  
High Temperatures ◽  
Electric Furnace ◽  
Cuprous Oxide ◽  
The Other ◽  
Resistance Furnace ◽  
Heterogeneous Equilibrium ◽  
Other Hand ◽  
Large Current ◽  
Dissociation Pressures ◽  
Reduction Of Oxides

This furnace was designed with a view to investigating at temperatures up to 1500° C. certain cases of heterogeneous equilibrium in which the equilibrium is defined by the pressure of the system. Instances are the dissociation of certain oxides, nitrides, and carbonates, and the reduction of oxides by carbon. The furnace could not be constructed of carbon, as carbon would react with some of the gases of which the pressure had to be measured, and also because it is almost impossible to remove the adsorbed gases from large quantities of carbon. Tubes of Royal Berlin porcelain in a platinum-wound resistance furnace may be used for temperatures up to 1200°, but at about this temperature they become soft, while the glaze runs and combines with any boat or other substance in the furnace. Tubes of silica are not suitable, because they are porous at high temperatures, and because they disintegrate owing to crystallisation taking place. It was decided to make the furnace of a platinum tube and to heat it by passing a large current through it. As some of the substances which it would be necessary to place in the furnace react with platinum, e. g . copper formed by the dissociation of cuprous oxide, it was necessary to make the furnace sufficiently large to take a boat or crucible of magnesia large enough to contain the reacting substance and thick enough to protect the tube. On the other hand, the tube ought to be as small as possible, in order that in determining the dissociation pressures all the charge should not be decomposed before the equilibrium is attained.

scholarly journals Effects of Heating Rate on Formation of Globular and Acicular Austenite during Reversion from Martensite

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 266 ◽  
Author(s):  
Xianguang Zhang ◽  
Goro Miyamoto ◽  
Yuki Toji ◽  
Tadashi Furuhara
Keyword(s):  
Heating Rate ◽  
High Temperatures ◽  
The Other ◽  
Growth Mode ◽  
High Heating Rate ◽  
Heating Rates ◽  
Other Hand ◽  
High Heating ◽  
Martensite Matrix

The effects of heating rate on the formation of acicular and globular austenite during reversion from martensite in Fe–2Mn–1.5Si–0.3C alloy have been investigated. It was found that a low heating rate enhanced the formation of acicular austenite, while a high heating rate favored the formation of globular austenite. The growth of acicular γ was accompanied by the partitioning of Mn and Si, while the growth of globular γ was partitionless. DICTRA simulation revealed that there was a transition in growth mode from partitioning to partitionless for the globular austenite with an increase in temperature at high heating rate. High heating rates promoted a reversion that occurred at high temperatures, which made the partitionless growth of globular austenite occur more easily. On the other hand, the severer Mn enrichment into austenite at low heating rate caused Mn depletion in the martensite matrix, which decelerated the reversion kinetics in the later stage and suppressed the formation of globular austenite.

The Role of the Haemocytes in the Growth and Moulting of an Insect, Rhodnius Prolixus (Hemiptera)

1955 ◽  
Vol 32 (4) ◽  
pp. 649-663
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
High Temperatures ◽  
Blood Cells ◽  
Trypan Blue ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Crystalline Material ◽  
The Other ◽  
Full Activity ◽  
Other Hand

Moulting in Rhodnius is greatly delayed by the injection of trypan blue, indian ink or iron saccharate, which are taken up by the phagocytic blood cells (amoebocytes). This delay occurs only when the injections are made during the first 3 days after feeding, not on the fourth day or later. On the fourth day after feeding the amoebocytes become filled with secretory vacuoles which restrict the uptake of indian ink or iron saccharate. When the amoebocytes are blocked by such injections within a day after feeding, the secretory activity of the thoracic gland is greatly reduced. This is proved histologically and experimentally. On the other hand, moulting induced by implantation of a fully active thoracic gland is not delayed by blocking the haemocytes. It is therefore concluded that some substance secreted by the haemocytes is necessary for the full activity of the thoracic glands. The crystalline hormone isolated by Butenandt & Karlson from the silkworm will induce moulting in the decapitated Rhodnius larva and in the isolated abdomen. Its action is not inhibited or delayed by the injection of indian ink or iron saccharate. This supports the conclusion that it is the product of the thoracic gland. Sublethal high temperatures will inhibit moulting in Rhodnius even when it is provided with abundant hormone by injection of the crystalline material or by joining in parabiosis with a moulting larva.

Economics of the Abrasive Cutoff Operation

1967 ◽  
Vol 89 (3) ◽  
pp. 514-518
Author(s):  
D. A. Farmer ◽  
M. C. Shaw
Keyword(s):  
Wear Rate ◽  
High Temperatures ◽  
Feed Rate ◽  
Minimum Cost ◽  
The Other ◽  
Minimum Rate ◽  
Other Hand ◽  
The Cost ◽  
Minimum Wear

A minimum rate of wear exists at a particular downfeed rate in the abrasive cutoff operation. When the feed rate is lower than this value, wear is excessive due to high temperatures in the outer portions of the wheel. On the other hand, when the feed rate is higher than the minimum wear rate value, wear is also excessive due to insufficient space between active grains to accommodate the chips. In practice, a feed rate somewhat higher than the mininum wear rate value should be chosen since this will correspond to minimum cost per cut. Methods of arriving at the cost optimum downfeed rate for the abrasive cutoff operation are presented, including special charts for use in the workshop.

Electrochemical Hydriding of Mg-Based Alloys

2011 ◽  
Vol 312-315 ◽  
pp. 882-887
Author(s):  
Dalibor Vojtěch ◽  
Vítězslav Knotek ◽  
Pavel Novák
Keyword(s):  
Hydrogen Storage ◽  
High Temperatures ◽  
Room Temperature ◽  
Hydrogen Atmosphere ◽  
The Other ◽  
High Hydrogen ◽  
Hydrogen Saturation ◽  
Other Hand ◽  
Mechanism And Kinetics ◽  
Storage Methods

Mg-based alloys are prospective materials for reversible hydrogen storage in the form of metallic hydrides. Usually, hydrogen saturation is carried out at high temperatures and high hydrogen pressures. This is the reason for the high cost of metallic hydrides in comparison with other hydrogen storage methods. Electrochemical hydriding, on the other hand, can be realized at room temperature. Moreover, this process does not need any hydrogen atmosphere. In the presented work, electrochemical hydriding of several Mg-Ni-Mm-based alloys (Mm = mishmetal) is performed. Hydriding efficiency, mechanism and kinetics are described. It is shown that the additions of Ni, Mm and the formation of eutectic structures support hydriding of alloys.

Robustness of the Gaussian interferometric power in two optomechanical systems

2018 ◽  
Vol 16 (02) ◽  
pp. 1850015
Author(s):  
Y. Es-sahely ◽  
J. El Qars ◽  
M. Daoud ◽  
R. Ahl Laamara
Keyword(s):  
High Temperatures ◽  
Quantum Correlations ◽  
The Other ◽  
Optomechanical Systems ◽  
Separable States ◽  
Separability Criterion ◽  
Other Hand ◽  
Two Systems

In two optomechanical systems, we study the robustness of the Gaussian interferometric power (GIP) against thermal noises. We use the Mancini et al. criterion to distinguish between entangled and separable states. Also, we employ the GIP to capture the nonclassical feature of the two studied systems beyond entanglement. We evaluate explicitly these two indicators of nonclassicality as functions of parameters characterizing the environment and the optomechanical systems (temperature, coupling, etc). We show that the inseparable quantum correlations decay strongly enough than those existing in separable states under thermal noises. On the other hand, when the separability criterion failed, the GIP remains almost constant and nonzero in the two systems even for high temperatures. This show that the GIP is an appropriate measure to capture the quantumness of correlations especially for systems coupled to environment strongly affected by thermal noises.

Flower initiation in Trifolium subterraneum L. 1. Analysis of the partial processes involved

1959 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
LT Evans
Keyword(s):  
High Temperatures ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
Controlled Environment ◽  
Flower Initiation ◽  
Inhibitory Process ◽  
Inhibitory Effects ◽  
Other Hand ◽  
Short Days

The influence of various temperature and photoperiod regimes on flower initiation and flowering in eight strains of T. subterraneum has been examined, using the controlled environment facilities of the Earhart Laboratory. Flower initiation in subterranean clover appears to be under the control of three interacting partial processes, two of which are synergistic and promotive while the third is inhibitory. The promotive processes are possibly both light-independent, one being favoured by high temperatures and the other (the vernalization process) by low temperatures. The inhibitory process, on the other hand, is restricted to the diurnal dark period and is favoured by high temperatures. The interaction between the vernalization and dark inhibitory processes is such that in the absence of dark inhibition no vernalization is required by any strain, while on. the other hand sufficient vernalization can apparently overcome all dark inhibitory effects. Treatment with gibberellic acid eliminates the need for vernalization by plants of at least one early-flowering strain when. grown in short days at high temperatures. The strains of subterranean clover differ markedly in their responses to the three partial processes. In their response to the dark inhibitory process two strains are more affected by night temperature than by night length, while in two other strains the opposite is the case, which suggests that the dark inhibitory process could be resolved into more than one component.

Casting Finger Rings in Mycenaean Times: Two Unpublished Moulds at the National Archaeological Museum, Athens

2009 ◽  
Vol 104 ◽  
pp. 311-319 ◽  
Author(s):  
Eleni Konstantinidi-Syvridi ◽  
Maria Kontaki
Keyword(s):  
High Temperatures ◽  
Construction Method ◽  
The Other ◽  
Cylindrical Shape ◽  
Other Hand ◽  
Limited Class ◽  
Single Use

The recording of two unpublished moulds in the storeroom of the Prehistoric Collections of the National Archaeological Museum, Athens, presented here, provide the stimulus for a re-examination of the construction method of the bezeled/signet rings of Mycenaean times. The moulds, one of semi-cylindrical shape and the other rectangular, belong to a limited class of items from Crete, Mainland Greece, and Enkomi, Cyprus.It is possible that such moulds have served for the construction of the wax model of the artefacts, in the lost wax technique and not directly for the cast of gold, since the very construction of them, which is time-consuming and necessitates the skills of specialized craftsmen, indicates that they did not serve for a single use but rather for several uses. On the other hand, even steatite, the stone mostly used for such moulds, cannot adhere to continuous pressure to high temperatures, necessary for casting gold.Στην παρούσα μελετη καταγράφονται δύο αδημοσίευτες μήτρες από την αποθήκη της Προϊστορικής Συλλογής του Εθνικού Αρχαιολογικού Μουσείου στην Αθήνα, προσφέροντας το ερέθισμα για μία επανεξέταση της τεχνικής κατασκευής των δακτυλιδιών με σφενδόνη της Μυκηναϊκής εποχής. Οι μήτρες, από τις οποίες η μία είναι ημικυλινδρική και η άλλη ορθογώνια, ανήκουν σε μία περιορισμένη τάξη ευρημάτων, που προέρχονται από την Κρήτη, την Ηπειρωτική Ελλάδα και την Έγκωμη της Κύπρου.Είναι πιθανό ότι αυτές οι μήτρες να χρησιμοποιήθηκαν για την κατασκευή των κέρινων εκμαγείων των δακτυλιδιών κατά την τεχνική του «χαμένου κεριού» και όχι για την απευθείας χύτευση χρυσού. Η ίδια η κατασκευή τους, που προϋποθέτει πολύ χρόνο και ειδικευμένους τεχνίτες, υποδεικνύει ότι δεν χρησιμοποιήθηκαν μόνο για μία φορά. Από την άλλη πλευρά, ακόμη και ο στεατίτης, ο λίθος που κατεξοχήν χρησιμοποιήθηκε για την κατασκευή αυτών των αντικειμένων, δεν θα μπορούσε να αντέξει τις υψηλές θερμοκρασίες, που απαιτούντοα για την χύτευση του χρυσού σε διαδοχικές χρήσεις.

scholarly journals Deterioration rates of brazilwood seeds (Caesalpinia echinata Lam.) under high temperatures

Hoehnea ◽  
2017 ◽  
Vol 44 (3) ◽  
pp. 449-463 ◽  
Author(s):  
Márcia Regina Oliveira Santos ◽  
Claudio José Barbedo
Keyword(s):  
Mathematical Models ◽  
Ambient Temperature ◽  
Water Content ◽  
High Temperatures ◽  
The Other ◽  
Rapid Deterioration ◽  
Other Hand ◽  
Freezing Temperatures ◽  
Caesalpinia Echinata ◽  
Irregular Behavior

ABSTRACT Caesalpinia echinata seeds deteriorate in less than three months at ambient temperature, although they can remain viable for up to five years when kept under freezing temperatures. We studied the deterioration of brazilwood seeds when submitted to different conditions of temperature and humidity aiming to check the applicability of mathematical models for predicting loss of viability of those seeds. The results showed that the high temperatures preconized for the rapid deterioration and simulation of storability produced an irregular behavior, suggesting that the deteriorative metabolism of these seeds may not correspond to the metabolism during the natural storage. Applying the equations, seeds with 8% water content stored at 7 ºC could be stored for five years, while the literature shows that these seeds would not tolerate more than a year. On the other hand, the prediction of storage with 10% of water content at -18 ºC would be, by these equations, 128 years, while the literature shows that seeds under these conditions would lose viability in less than ten years. The results showed that the current models might present restrictions on their application, depending on the species and conditions.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

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