Electrical response of mortar with different degrees of saturation and deicing salt solutions during freezing and thawing

2015 ◽  
Vol 59 ◽  
pp. 49-59 ◽  
Author(s):  
Yaghoob Farnam ◽  
Heather Todak ◽  
Robert Spragg ◽  
Jason Weiss
Keyword(s):  
Electrical Response ◽  
Salt Solutions ◽  
Freezing And Thawing ◽  
Deicing Salt

Effectiveness of sealers in counteracting alkali-silica reaction in highway median barriers exposed to wetting and drying, freezing and thawing, and deicing salt

2002 ◽  
Vol 29 (2) ◽  
pp. 329-337 ◽  
Author(s):  
Marc-André Bérubé ◽  
Dominique Chouinard ◽  
Michel Pigeon ◽  
Jean Frenette ◽  
Michel Rivest ◽  
...  
Keyword(s):  
Salt Water ◽  
Alkali Silica Reaction ◽  
Freezing And Thawing ◽  
Wetting And Drying ◽  
Deicing Salt ◽  
Concrete Members ◽  
Aesthetic Appearance ◽  
Concrete Cylinders ◽  
The Aesthetic ◽  
High Alkali

This study follows another experimental study where different types of sealers were applied on plain and air-entrained large concrete cylinders made with high-alkali contents and highly alkali–silica reactive limestone aggregates. The main objective was to determine the effectiveness of these sealers in counteracting concrete expansion and surface deterioration due to alkali–silica reaction under various exposure conditions. This study indicated that all three sealers tested, the silane-, oligosiloxane-, and polysiloxane-based sealers, could stop concrete expansion due to ASR and even produced contraction, even for concrete cylinders subjected to wetting and drying, freezing and thawing, and sodium chloride solutions. In 1991, the same silane, oligosiloxane, and polysiloxane were applied on sections of median barriers showing various degrees of deterioration due to ASR. These sections were subjected to wetting and drying, freezing and thawing, and, during winter, to deicing salt. The silane was also applied on other sections of the same barriers in 1994. Observations and measurements over 10 years indicate that the aesthetic appearance of these median barriers, particularly those sealed with the silane, was greatly improved, while internal humidity was significantly reduced, and concrete expansion as well, when not arrested. The period of time during which the above three sealers were capable to stop ASR expansion varies with the sealer used and the degree of concrete deterioration at the time of sealing. For instance, the silane, which was the best among all products tested, caused concrete contraction for at least 6 years in median barriers that were severely affected by ASR, and likely for more than 10 years in moderately affected barriers. The overall results confirm the conclusions obtained previously in the laboratory: a good sealer such as the silane tested may greatly improve the aesthetic appearance and stop the expansion of non-massive ASR-affected concrete members, at least up to about 300 mm in thickness, and subjected to wetting and drying, freezing and thawing, and salt water. However, the poor result obtained in the field with another silane-based sealer indicates that a sealer cannot be selected based on its composition only.Key words: alkali–silica reaction, concrete; cracking, expansion, internal humidity, median barrier, sealer, silane, siloxane.

Migration of ions of chemical elements in freezing and frozen soils

Polar Record ◽  
1999 ◽  
Vol 35 (192) ◽  
pp. 59-66 ◽  
Author(s):  
E. M. Chuvilin
Keyword(s):  
Chemical Elements ◽  
Salt Solutions ◽  
Freezing And Thawing ◽  
Frozen Soils ◽  
Ionic Permeability

AbstractThis paper examines the behaviour of ions of chemical elements in freezing and thawing soils and in ice, and analyzes the mechanisms and laws that govern the transfer of ions. Data are given on the ionic permeability of frozen soils and ice. The features characteristic of the interaction of frozen soils with salt solutions are described.

scholarly journals REVERSIBLE INACTIVATION OF TYPHUS RICKETTSIAE

1954 ◽  
Vol 38 (2) ◽  
pp. 169-179 ◽  
Author(s):  
Marianna R. Bovarnick ◽  
Emma G. Allen
Keyword(s):  
Salt Solution ◽  
Hemolytic Activity ◽  
Coenzyme A ◽  
Salt Solutions ◽  
Freezing And Thawing ◽  
Reversible Inactivation ◽  
Low Concentrations ◽  
Isotonic Salt Solution

Rickettsiae that have been frozen and thawed in isotonic salt solutions show greatly decreased toxicity for mice, hemolytic activity, respiration, and infectivity for eggs. All these properties can be partially restored by incubation of the rickettsiae in the presence of DPN and coenzyme A for 2 hours at 34°C. The extent of both inactivation and of subsequent reactivation is markedly affected by the presence of low concentrations of sucrose during the process of freezing and thawing. It has been shown that DPN is present in rickettsial suspensions and that in preparations that have not been frozen, the DPN sediments with the rickettsiae. After freezing in isotonic salt solution the DPN becomes non-sedimentable.

scholarly journals Denaturation of proteins in muscle juice by freezing

1932 ◽  
Vol 111 (772) ◽  
pp. 396-411 ◽  
Keyword(s):  
Freezing Point ◽  
Salt Solutions ◽  
Freezing And Thawing ◽  
Excellent Opportunity ◽  
Point Curve ◽  
Protein Particles ◽  
Frozen State ◽  
Denaturation Of Proteins ◽  
Number Of Particles

During an investigation on the freezing point curve of ox muscle juice, it was observed that upon thawing a sample which had been held in the frozen state at — 3° C. for some time, a flocculent precipitate of protein formed. Further experiments showed that the precipitation depended upon the conditions of freezing. A search of the literature yielded little information regarding the phenomenon, practically the only investigation bearing directly on it being that of Vickery (1926), who, though he did not observe precipitation, states that the number of particles visible under the ultra microscope diminished after freezing and thawing, owing, as he thought, to an aggregation of protein particles. The precipitated protein was found to be insoluble in salt solutions, and was, n fact, denatured. The circumstances of this denaturation are interesting, for nothing more is involved than the removal of water from the system by freezing, and as this factor can be quantitatively controlled, the system affords an excellent opportunity for studying the mechanism of denaturation.

scholarly journals Effects of Cardiac Glycosides on Electrical Activity in the Isolated Retina of the Frog

1967 ◽  
Vol 50 (6) ◽  
pp. 1585-1606 ◽  
Author(s):  
Robert N. Frank ◽  
Timothy H. Goldsmith
Keyword(s):  
Atpase Activity ◽  
Electrical Activity ◽  
Cardiac Glycosides ◽  
Time Course ◽  
Sodium Pump ◽  
Electrical Response ◽  
Irreversible Change ◽  
Salt Solutions ◽  
Frog Retina ◽  
Isolated Retina

Ouabain added to physiological salt solutions bathing the isolated frog retina irreversibly abolishes the electrical response to light (the electroretinogram or ERG). The time course of abolition depends on the concentration of ouabain in the medium and the surface of the retina to which it is applied. When the glycoside is placed on the receptor surface, in 7 min the ERG is completely eliminated by 10-4 M ouabain and more than 90% inhibited by 3 x 10-5 M ouabain. The effect is slower at lower concentrations and when the solution is applied to the vitreous surface of the retina. The evidence suggests that abolition of the ERG by ouabain is due principally to inhibition of the active transport of sodium: (a) Structurally modified glycosides which are considerably less potent inhibitors of alkali cation-activated ATPase activity in preparations of frog retinal outer segments are also poorer inhibitors of electrical activity in isolated retinas. (b) Replacing much of the sodium in the medium bathing the retina by choline, Tris, or sucrose significantly protects the retina from ouabain. It is suggested that in a standard sodium environment essentially constant activity of the sodium pump is required to prevent rapid and irreversible change. The cellular sites most critically dependent on the sodium pump have not been identified.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Three-Dimensional Structure of Cloned T3 Connector Protein at 1.6nm Resolution

1990 ◽  
Vol 48 (1) ◽  
pp. 282-283
Author(s):  
José L. Carrascosa ◽  
José M. Valpuesta ◽  
Hisao Fujisawa
Keyword(s):  
Dna Sequences ◽  
Expression Vector ◽  
Three Dimensional ◽  
Deae Cellulose ◽  
Dna Packaging ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Freezing And Thawing ◽  
Three Dimensional Structure ◽  
Dimensional Reconstruction

The head to tail connector of bacteriophages plays a fundamental role in the assembly of viral heads and DNA packaging. In spite of the absence of sequence homology, the structure of connectors from different viruses (T4, Ø29, T3, P22, etc) share common morphological features, that are most clearly revealed in their three-dimensional structure. We have studied the three-dimensional reconstruction of the connector protein from phage T3 (gp 8) from tilted view of two dimensional crystals obtained from this protein after cloning and purification.DNA sequences including gene 8 from phage T3 were cloned, into Bam Hl-Eco Rl sites down stream of lambda promotor PL, in the expression vector pNT45 under the control of cI857. E R204 (pNT89) cells were incubated at 42°C for 2h, harvested and resuspended in 20 mM Tris HC1 (pH 7.4), 7mM 2 mercaptoethanol, ImM EDTA. The cells were lysed by freezing and thawing in the presence of lysozyme (lmg/ml) and ligthly sonicated. The low speed supernatant was precipitated by ammonium sulfate (60% saturated) and dissolved in the original buffer to be subjected to gel nitration through Sepharose 6B, followed by phosphocellulose colum (Pll) and DEAE cellulose colum (DE52). Purified gp8 appeared at 0.3M NaCl and formed crystals when its concentration increased above 1.5 mg/ml.

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