Hydrophobic treatments measurement

After eight years of exposure, an extensive examination was started in 1994 to evaluate the effectivity and durability of the water repellent treatments [4]. Macroscopic tests as water uptake measurements were carried out to determine the remaining effect of the protective organosilicon layer. Due to the fact that surface information from hydrophobic treatment of mineral surfaces is supplied by surface sensitive measuring techniques, TOF-SIMS and additional DRJFT-studies on treated and exposed material were performed. 

Analogously, correlations exist between the coefficient of water permeabihty k and that of capillary absorption S, but these lose their validity if the surface of the concrete is subjected to a hydrophobic treatment, which will reduce considerably capillary absorption but not permeation. For concrete obtained with Portland cement, correlations between the coefficient of water permeability (k) and conductivity (o = 1/p) measured for a given value of relative humidity are available. On the other hand, conductivity varies greatly in concrete made with blended cements or carbonated concrete, while there is no significant change in water permeability. 

In general, it can be concluded that hydrophobic treatment of concrete is an effective and low-cost preventative measure against corrosion that may be caused by chloride ingress. The beneficial effect is mainly a strong reduction of chloride ingress, both in semi-permanent contact and in wetting/drying situations. The effective life in fully exposed atmospheric conditions is at least five years and more, probably much more, when protected from UV radiation by a layer of asphalt... 

NTNU Internal test method KB 71127- Hydrophobic Surface Treatment. Measurements of Penetration Depth into Concrete, Trondheim (1998). 

Texturization is not measured directly but is inferred from the degree of denaturation or decrease of solubility of proteins. The quantities are determined by the difference in rates of moisture uptake between the native protein and the texturized protein (Kilara, 1984), or by a dyebinding assay (Bradford, 1976). Protein denaturation may be measured by determining changes in heat capacity, but it is more practical to measure the amount of insoluble fractions and differences in solubility after physical treatment (Kilara, 1984). The different rates of water absorption are presumed to relate to the degree of texturization as texturized proteins absorb water at different rates. The insolubility test for denaturation is therefore sometimes used as substitute for direct measurement of texturization. Protein solubility is affected by surface hydrophobicity, which is directly related to the extent of protein-protein interactions, an intrinsic property of the denatured state of the proteins (Damodaran, 1989 Vojdani, 1996). 

These data show clearly that the structure-property relationships which apply to hydrophobic organic chemicals such as the chloro- and alkyl-aromatics also apply to the phenols, but the relationships are more scattered and less well defined. The absolute values of properties differ greatly. This scatter is probably attributable, in part, to insufficient experimental data or errors in experimental measurements, to dissociation and to the greater polar character of these chemicals. It is not recommended that correlations developed for non-polar organic chemicals be applied to the phenols. Separate treatment of each homologous series is required. 

Artola-Garicano et al. [24] measured the free and total concentrations of AHTN and HHCB in the influent of a wastewater treatment plant in The Netherlands every 2 h over a 24-h period. Their data indicate that the variation in total concentration of AHTN and HHCB in influent was 19%, while the variation in free concentration was less than 10% over the 24-h period. These authors suggested that fluctuations in water volume cause fluctuations in total concentrations however, for hydrophobic FMs such as AHTN and HHCB, the solids act as a reservoir and stabilize the free concentrations. 

The surface of silica turns hydrophobic on treatment with organo-silicon chlorides. Water vapor adsorption isotherms measured by Stober (219) showed a very marked decrease in reversible adsorption. Less than 0.3 primary adsorption centers per 100 A remained in the surface after covering with the organosiloxane layer. Similar effects were observed in the adsorption of ammonia. About 2.2 silanol groups per 100 A had not reacted with the trimethylsilyl chloride. Nevertheless, the greater part of these had become unaccessible for water vapor. Apparently, they were hidden underneath a trimethylsilyl umbrella. ... 

DNA immobilized by organosilane chemistries has proven to be an effective method for measuring impedance changes upon hybridization using both gold and platinum electrodes [21,50]. The effect of different silane chemistries creates differences in the hydrophobicity and hydration levels of the modified surface. The organosilane treatment along with the ssDNA... 

The increase in the atomic concentration of oxygen (Table 1) suggests an increased amount of hydrophilic groups on the wool surface. This fact can be confirmed by the results of the contact angle measurements (Table 2). Following enzymatic treatment the contact angle is distinctly decreased, from 122.5° for untreated wool to 108° and even 102°, but the wool fabric surface is still hydrophobic (0 > 90°). The contact angle value obtained for wool after an intensive treatment (4% o.w.f. of enzyme) equals the one for wool samples with chitosan deposited. 

Figure 9. A. Thermotropic fluorescence spectra of E. coli DH1 cells using the hydrophobic probe, N-phenyl-1 -naphthylamine (NPN). (a) Mid-log phase cells (b) stationary phase cells (c) cells made genetically transformable by the method of Hanahan.146 NPN was added to 4 mL of cell culture to a final concentration of 1 pM and the thermotropic fluorescence spectra were recorded.24 Measurements were made at increasing temperature (ca. 2 °C per min). Excitation 360 nm emission 410 nm. Measurements were made at increasing temperature (ca. 2 °C per min). B. Effects of physical treatments on the thermotropic transitions in genetically competent E. coli DH1. (a) Thermotropic transitions at descending temperature (b) cells pelleted at low speed and suspended in supernatant (c) as in b but suspended in equal volume of distilled water (d) as in (b) but suspended in 10 mM phosphate buffer, pH 7.4. Excitation 360 nm emission 410 nm. Fluorescent probe was NPN. Measurement (a) was made at decreasing temperature and (b), (c), (d) at increasing temperatures (ca. 2 °C per min).

A report is presented on the fluorination of the inner surface of blood circulating tubes made from PVC using APG discharge treatment in order to enhance biocompatibility and suppress the bleeding of plasticisers from the PVC. A hydrophobic surface was produced on the inner surface of the tube by polymerising hexafluoropropylene or tetrafluoroethylene and the treated surfaces analysed by X-ray photoelectron spectroscopy, FTIR-ATR spectroscopy and contact angle measurements. 17 refs. 

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