Solvation in Supercritical Fluids

2005 ◽  
Author(s):  
Eldred H. Chimowitz
Keyword(s):  
Carbon Dioxide ◽  
Molecular Weight ◽  
Supercritical Fluids ◽  
Acceptable Alternative ◽  
Fluid Systems ◽  
Organic Solid ◽  
Large Molecular Weight ◽  
Halogenated Solvents ◽  
Miscible Liquids ◽  
Solute Species

The use of supercritical fluids as solvent media is driven mainly by the need to reduce the use of organic and halogenated solvents in chemical processes. In the future, one of the main aims of research in this area will be to supplant organic solvent use in many of these processes with solvents such as supercritical carbon dioxide, environmentally a much more acceptable alternative. One of the most common engineering requirements in this area is the need to predict solubility, and other thermodynamic behavior, in high-pressure mixtures where the solvent is close to its critical point and contains nonvolatile solute species of large molecular weight present in small amounts. In this chapter, we address this problem focusing upon solvation in organic solid–supercritical fluid systems which are among the most technologically interesting. The extension of the analyses presented here to situations where the condensed phase may be a mixture of miscible liquids, for example, is straightforward and left to a problem in the additional exercises.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

RFID-Based Thermal Bubble Non-Floating Type Accelerometer with Semi-Cylindrical Chamber and Filled with Xenon Gas

2011 ◽  
Vol 317-319 ◽  
pp. 1153-1162
Author(s):  
Jium Ming Lin ◽  
Po Kuang Chang ◽  
Cheng Hung Lin ◽  
Qi Kun Zhang
Keyword(s):  
Carbon Dioxide ◽  
Molecular Weight ◽  
Response Time ◽  
Flexible Substrate ◽  
Thermal Sensors ◽  
Cylindrical Chamber ◽  
Floating Structure ◽  
Key Technology ◽  
Impact Condition ◽  
Floating Type

This research proposes a wireless RFID-based thermal bubble accelerometer design, and relates more particularly for the technology to manufacture and package it on a flexible substrate. The key technology is to integrate both a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for fabrication and usage. In this paper the heaters as well as the thermal sensors are directly adhering on the surface of the flexible substrate without the traditional floating structure. Thus the structure is much simpler and cheaper for manufacturing, and much more reliable in large acceleration impact condition without broken. Furthermore, the molecular weight of xenon gas is much larger than carbon dioxide, thus the performance of the accelerometer will be increased. In addition, the shape of the chamber is changed as a semi-cylindrical one instead of the conventional rectangular type. Comparisons of sensitivity and response time are also made; one can see the performances of the proposed new design with either semi-cylindrical chamber or filled with xenon gas are better.

scholarly journals Association of large molecular weight proteasome 7 gene polymorphism with ankylosing spondylitis

1998 ◽  
Vol 41 (3) ◽  
pp. 560-562 ◽  
Author(s):  
A. Fraile ◽  
A. Nieto ◽  
J. Vinasco ◽  
Y. Bera�n ◽  
J. Mart�n ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ankylosing Spondylitis ◽  
Gene Polymorphism ◽  
Large Molecular Weight

The Influence of Temperature and Concentration on Copper Deposition Kinetics in Supercritical Carbon Dioxide

2004 ◽  
Vol 812 ◽  
Author(s):  
Yinfeng Zong ◽  
James J. Watkins
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluids ◽  
Zero Order ◽  
Copper Deposition ◽  
Deposition Kinetics ◽  
Zero Order Kinetics ◽  
Concentration Interval ◽  
Kinetics Of ◽  
Supercritical Carbon

AbstractThe kinetics of copper deposition by the hydrogen-assisted reduction of bis(2,2,7- trimethyloctane-3,5-dionato)copper in supercritical carbon dioxide was studied as a function of temperature and precursor concentration. The growth rate was found to be as high as 31.5 nm/min. Experiments between 220 °C and 270 °C indicated an apparent activation energy of 51.9 kJ/mol. The deposition kinetics were zero order with respect to precursor at 250 °C and 134 bar and precursor concentrations between 0.016 and 0.38 wt.% in CO2. Zero order kinetics over this large concentration interval likely contributes to the exceptional step coverage obtained from Cu depositions from supercritical fluids.

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