Penetration experiments

Mortar specimens were prepared to determine the effectiveness of MRI in a time resolved lithium penetration experiment [15]. This work used a non-reactive aggregate and commercially available LiN03 solution to simulate topical treatments to concrete. These results will aid the development of a more general measurement of concrete core extracted from a lithium treated structure suffering from ASR. 

Fig. 2 Schematic diagram of vertically oriented linear penetration experiment for Ci2(EO)5/H20 at 28 °C. a Initial contact b later showing intermediate lamellar phase...

Fig. 13.36 The fractional coverage during nonisothermal gas-penetration experiments in PB-300, where the gas was injected after different F0 = at/R, that is, dimensionless delay times, following the step bath temperature switchover from 60° to 0°C. [Reprinted by permission from K. W. Koelling, V. Gauri, M. Tendulkar, R. Kaminski, and O. Becker, Understanding the Controlling Mechanisms of Gas-assisted Injection Molding through Visualization, SPE ANTEC Tech Papers, 43, 3697 (1997).]...

More recent penetration experiments were carried out in biological systems, that is, large intact nuclei [35], giant liposomes [36], and mammalian cells [37]. Such experiments can provide information about the distribution of electroactive species inside the cell, potentials, and ion transfers across biological membranes (see Section V.F). 

Although disk-shaped tips are typically most useful for SECM experiments, it is not always possible to produce such tips, especially when they have to be nanometer sized. For some special applications (e.g., penetration experiments), one may want to purposely fabricate tips with different geometries. To characterize nondisk shaped tips, experimental approach curves were obtained and then compared to simulated ones [12]. A number of UME tip geometries including hemispheres [14, 15], spheres [16], rings [17], ring-disks [18], and etched electrodes [19, 33] have been characterized in this way. 

Capillary penetration experiments. Using a series of nonpolar and polar probe liquids, the solid surface tension of unmodified and modified particles was evaluated by capillary penetration experiments [35,36], The strategy is based on a modified Washburn equation ... 

The components in a simple penetration experiment consist of a surfactant, water-soluble herbicide, and water. Since the surfactant is at a concentration of 0.5 to 1%, it interacts with water and forms micelles. Since micelles are formed, these could solubilize some of the herbicide inside the micelle. Now we have five components, (1) water, (2) surfactant monomer, (3) surfactant micelle, (4) micelle with solubilized herbicide, and (5) an herbicide in anhydrous or hydrated form which all come in contact with the plant. Which one or more of these components has the greatest effect on the plant Before a thorough understanding of this phenomenon can be achieved, the interaction of each of these components with a plant must be investigated separately, and perhaps the plant is too complex for initial study. Perhaps a homogeneous semipermeable membrane could be used instead. 

The sample was dried completely and a second water penetration experiment was carried out. The maximum uptake of water occurred once again after 24 h of soaking however, the slope of the profile was less pronounced, as illustrated in Fig. 17. Furthermore, the peak intensity was lower in the second experiment, which is evidence of a smaller pore size distribution in the sample, suggesting that some degree of rehydration took place in this sample during the course of the first water penetration study. This result was further verified by mercury intrusion porosimetry. 

Fig. 17. Comparison of the peak water uptake into the w/c = 0.4 sample during the first and second water penetration experiments.

Techniques for phase identification are similar to those employed for thermotropic liquid crystals, although there are differences. Thus, optical microscopy is the most common technique used, but rather than prepare multiple samples at a range of concentrations it is more common to perform Lawrence Penetration Experiments [189]. In this experiment, some solid surfactant (maybe up to 50 mg) is placed on a microscope slide and a cover slip placed on the top. Water (or which ever solvent is to be used) is placed at the end of the cover slip and proceeds from one end to the other by capillary action, thus, setting up a concentration gradient across the sample. Now, at any given temperature, it is possible to have a snapshot of the whole phase diagram, and clear phase boundaries can often be seen. This experiment can be very... 

Analysis of Penetration Experiments According to the Classical Approach... 

TiTuch of our understanding of the phase behavior of insoluble - monolayers of lipids at the air-water interface is derived from Adam s studies of fatty acid monolayers (I). It is now clear that the phase behavior of phospholipid monolayers (2) parallels that of the fatty acids we make use of these structure variations in our study of the interactions of phosphatidylcholine (lecithin) monolayers with proteins. Because of the biological significance of the interfacial behavior of lipids and proteins, there is a long history of studies on such systems. When Adam was studying lipid monolayers, other noted contemporary surface chemists were studying protein monolayers (3) and the interactions of proteins with lipid monolayers (4). The latter interaction has been studied by many so-called 4 penetration experiments where the protein is injected into the substrate below insoluble lipid monolayers that are spread on the... 

There are two principal problems with penetration experiments the adsorption characteristics of the protein have to be understood, and the amount of protein that adsorbs to the interface when lipid is present has to be determined. Previously, most researchers used the change in film pressure (Atr) as a measure of the amount of protein that interacted with the lipid monolayer. However, this approach implicitly assumes that the adsorption of protein can be described by Gibbs adsorption equation, but as pointed out by Colacicco (6), this is invalid for proteins which adsorb irreversibly. Because the surface concentration of protein is unknown, radiolabeled proteins have been used (8, 9, 10). This work has been concerned exclusively with highly water-soluble proteins whose prime mode of interaction with monolayers (and bilayers) is electrostatic. In these cases a simple description of the packing in the mixed lipid-protein films was impossible (6). 

Industry uses acid cleavage of esters on a large scale for saponification of fats, favoring certain catalysts such as the rapid-acting Twitchell reagent. Schlutius76 carried out penetrating experiments on the nature and mode of action of these catalysts. 

The TMA technique can be used for Tg-value determinations, resin cure studies, penetration experiments or orientation effect determinations. The most important application is thought to be the linear thermal expansion coefficient (l.e.c.) determination of engineering polymers. An example of this application is given in chapter 3.1.2. The results of a polymer shrinkage experiment monitored by TMA are described in chapter 3.1.3. 

Hall proposed an experimental procedure, in which changes in the area of the monolayer in equilibrium with the soluble surfactants should be performed to keep constant or control the chemical potential of the first component when the activity of the second component is varied. To summarise, the rigorous thermodynamic analysis of the penetration equilibrium, based on the Gibbs equation, can neither provide an equation of state of the monolayer, nor an adsorption isotherm for the soluble component. This analysis only enables one to formulate the conditions for a penetration experiment, which are, however, very difficult to implement. Therefore, to describe the thermodynamic behaviour of real mixed monolayers, at present one should use some approximate theoretical models. 

Penetration systems at the air-water interface in which a dissolved amphiphile (surfactant, protein) penetrates into a Langmuir monolayer are interesting models for a better understanding of various complex processes. Most of all, penetration systems can simulate properties of biological membranes typically comprised of lipids mixed with proteins. First penetration experiments have been described by Schulman and Hughes in 1935 [110]. In the... 

Quantitative information on penetrated layers under dynamic and equilibrium conditions require much attention in respect to the experimental technique. There are a number of penetration experiments with different advantages and drawbacks. The classical experiment is the injection technique where a soluble component is injected into the subphase below a spread monolayer. Experiments can then be performed at constant monolayer coverage [212, 213, 214] or by compression and expansion cycles [215, 216]. Another possibility is to exchange the subphase below a spread monolayer using a laminar pumping system. Other experiments were performed by using the sweeping technique as described in [217, 218]. 

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