scholarly journals The Electrical Resistance of the Lower Consolute System 2,6-Lutidine?Water

1984 ◽  
Vol 37 (5) ◽  
pp. 549 ◽  
Author(s):  
AF Collings ◽  
N Bajenov ◽  
BD Inglis
Keyword(s):  
Binary Mixtures ◽  
Electrical Resistance ◽  
Critical Fluctuations ◽  
Temperature Range ◽  
Separation Temperature ◽  
The One ◽  
Glass Surfaces ◽  
Weak Divergence ◽  
Reduced Temperature

The one-phase electrical resistance of the lower consolute system 2,6-lutidine-water has been measured in the reduced temperature range 2x 10-6 < 8 < 0�11. Particular attention has been given to the drift in resistance and separation temperature caused by the leaching of ' ions during long contact with glass surfaces. When correction is made for this effect, no contribution to the electrical resistance due to critical fluctuations is observed. The effect of the leaching of ions has not been taken into account in previously published studies which have observed, and attempted to characterize, a weak divergence in the electrical resistance of critical binary mixtures.

Phase separation of binary mixtures induced by soft centrifugal fields

2021 ◽  
Author(s):  
Thomas Zemb ◽  
Rose Rosenberg ◽  
Stjepan Marčelja ◽  
Dirk Haffke ◽  
Jean-François Dufrêche ◽  
...  
Keyword(s):  
Phase Separation ◽  
Critical Point ◽  
Binary Mixtures ◽  
Liquid Mixture ◽  
Model System ◽  
Binary Liquid Mixture ◽  
Miscibility Gap ◽  
Critical Fluctuations ◽  
Binary Liquid

We use the model system ethanol–dodecane to demonstrate that giant critical fluctuations induced by easily accessible weak centrifugal fields as low as 2000g can be observed above the miscibility gap even far from the critical point of a binary liquid mixture.

Scanning UV microspectrophotometry as a tool to study the changes of lignin in hydrothermally modified wood

Holzforschung ◽  
2016 ◽  
Vol 70 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Bruno Andersons ◽  
Guna Noldt ◽  
Gerald Koch ◽  
Ingeborga Andersone ◽  
Anete Meija-Feldmane ◽  
...  
Keyword(s):  
Cell Wall ◽  
Degradation Products ◽  
Middle Lamella ◽  
Temperature Range ◽  
Wood Protection ◽  
Lower Temperature Range ◽  
Lower Temperature ◽  
The One ◽  
S2 Layer ◽  
Uv Microspectrophotometry

Abstract Thermal modification (TM) of wood has occupied a relatively narrow but stable niche as an alternative for chemical wood protection. There are different technological solutions for TM and not all details of their effects on wood tissue have been understood. The one-stage hydrothermal modification (HTM) at elevated vapour pressure essentially changes the wood’s composition and structure. In the present paper, the changes in three hardwood lignins (alder, aspen, and birch) were observed within the cell wall by means of cellular UV microspectrophotometry. The lignin absorbances in the compound middle lamella (CML) of unmodified wood are 1.7- to 2.0-fold higher than those in the fibre S2 layer. The woods were modified in the temperature range from 140 to 180°C, while in the lower temperature range (140°C/1 h), the UV absorbances are little affected. Essential changes occur in the range of 160–180°C and the UV data reflect these by absorbtion changes, while the absorbances at 278 nm rise with factors around 2 more in the S2 layer than in the CML. The absorbance increments are interpreted as polycondensation reactions with furfural and other degradation products of hemicelluloses with the lignin moiety of the cell wall.

scholarly journals Investigations of the Temperature Influence on Formation of Compounds from the BTEX Group During the Thermal Decomposition of Furan Resin / Badania wpływu temperatury na powstawanie związków z grupy BTEX podczas termicznego rozkładu żywicy furanowej

2013 ◽  
Vol 13 (2) ◽  
pp. 85-90 ◽  
Author(s):  
M. Kubecki ◽  
M. Holtzer ◽  
S. Żymankowska-Kumon
Keyword(s):  
Thermal Decomposition ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Temperature Influence ◽  
Temperature Range ◽  
Furan Resin ◽  
Volatile Organic ◽  
Synthetic Resins ◽  
Temperature Ranges ◽  
The One

Abstract Organic binders applied in foundry plants based on synthetic resins, from the one side influence obtaining the required technological properties by the moulding sand and - in consequence - obtaining good quality castings, and on the other side are the source of volatile organic compounds (VOC). Together with synthetic resins their hardeners, which although added in very small amounts emit during their thermal decomposition substances negatively influencing the natural environment, are also used. Both, resins and hardeners only at the influence of high temperatures accompanying moulds pouring with liquid metal generate harmful volatile organic compounds including compounds from the BTEX group. Investigations of the temperature influence on the kind and amount of organic compounds formed during the thermal decomposition of selected binders and hardeners and their mixtures allow to determine temperature ranges the most favourable for emitting harmful substances as well as to compare their emission from the selected materials. The aim of this study was the determination the temperature influence on formation substances from the BTEX group, during thermal decomposition of the selected binder, its hardener and their mixture. The BTEX group emission constitutes one of the basic criteria in assessing the harmfulness of materials applied for moulding and core sands and it can undergo changes in dependence of the applied system resin-hardener. Investigations were carried out on the specially developed system for the thermal decomposition of organic substances in the temperature range: 500ºC - 1300ºC, at the laboratory scale. The investigations subject was the furan resin, its hardener and hardened furan resin. The assessment of the emission degree of the BTEX group in dependence of the system subjected to the temperature influence was performed, within the studies. The temperature range, in which maximal amounts of benzene, toluene, ethylbenzene and xylenes were emitted from tested materials - was defined. The qualitative and quantitative analysis of the BTEX group were carried out with using the gas chromatography technique coupled with the mass spectrometry (GC/MS).

Thermoelectric Properties of High Density Sintered Ca3Co2O6

2008 ◽  
Vol 54 ◽  
pp. 211-215 ◽  
Author(s):  
Takeo Uesugi ◽  
Hitoshi Kohri ◽  
Ichiro Shiota ◽  
Masahiko Kato ◽  
Isao J. Ohsugi
Keyword(s):  
Solid State ◽  
Thermoelectric Properties ◽  
Solid State Reaction ◽  
Hot Pressing ◽  
Temperature Limit ◽  
Thermoelectric Oxide ◽  
Temperature Range ◽  
Seebeck Coefficients ◽  
The One ◽  
Lower Resistivity

Ca3Co4O9 is a promising material for thermoelectric generation, as it is stable up to 1173 K in the air, and shows good thermoelectric properties. Recently, it was found that Ca3Co2O6 was stable up to 1300 K in the air. The Ca3Co2O6 is decomposed phase of Ca3Co4O9 and the temperature limit is higher than one of Ca3Co4O9. The electrical resistivity of Ca3Co2O6 was, however, higher than the one of Ca3Co4O9. Not only high power generation performances but also excellent strength is required for practical use of the thermoelectric oxide materials. Polycrystalline samples of Ca3Co2O6 were prepared by solid-state reaction (SSR) and hot pressing (HP). Relative density of Ca3Co2O6 (HP) was over 98%, which is larger than the one of Ca3Co2O6 (SSR). Ca3Co2O6 (HP) showed larger strength and lower resistivity than Ca3Co2O6 (SSR). The resistivity (ρ) of Ca3Co2O6 (HP) in perpendicular to the pressurized direction decreased from 64 Ωcm to 4.0×10-2 Ωcm at the temperature range between 373 and 1173 K. In addition, the resistivity of this sample was decreased by heat treatment in the air. The Seebeck coefficients (S) of Ca3Co2O6 (HP) was positive value and more than 160 μVK-1 at the temperature range between 373 and 1173 K. Ca3Co1.8M0.2O6 (M= Mn or V) were prepared by solid state reaction and hot pressing. The resistivity of Mn-substituted Ca3Co2O6 (HP-Mn) and V-substituted Ca3Co2O6 (HP-V) were lower than the one of non-substituted Ca3Co2O6 (HP) at the temperature below 523 K for the Mn-substituted sample or 723 K for V-substituted sample. The latter showed the lowest value 1.53 Ωcm of all specimens at 383 K. The power factor (S2ρ-1) of Ca3Co2O6 (HP) was 88.3 μWm-1K-2, which is the largest of all specimens at 1176 K, but S2ρ-1 of V-substituted Ca3Co2O6 (HP-V) is the largest of all specimens up to 773 K.

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