They have a relatively high level of hydrophilicity. Conversely, cationic surfactants such as cetyltrimethyl ammonium bromide (CTAB) release a positive charge in an aqueous solution. On the other hand, in alkali pH, amphoteric surfactants act as anionic while in acid pH, it act as cationic. Non-ionic surfactants such as partially hydrolyzed PVA (polyvinyl alcohol) have no charge (Li et al, 2008). Among four types of surfactants, partially hydrolyzed PVA is most frequent used because it gives the smallest microsheres (Jeffrey et al, 1991).
An important feature of stimulation microelectrodes is its safe charge injection limit. The microelectrodes cannot exceed a certain limit of current density, otherwise gas evolution of oxygen or hydrogen may occur. Polycrystalline electrodes are limited to 5mC/cm2 whilst the conventional Tin electrodes have a safe limit of 20mC/cm2. The Au electrodes have a limit of 3mC/cm. However, polycrystalline electrodes can only cause an evolution when a negative potential is applied, thus demonstrating that these are well suited for the stimulation of electrogenic cells.
When the shock pressure and temperature are too low, the shock waves can not generate sufficient energy to produce carbon phase. An increase of pressure and temperature was observed to be favorable for the synthesis of carbon phases. Appropriate high pressure and low temperature are favorable for the synthesis of
2. Ferritic stainless steel - Ferritic stainless steels has good engineering properties when compared with austenitic stainless steel grades. In Ferritic stainless steel nickel and chromium content is low so it has low corrosion resistance. Ferritic stainless steels are normally less
Adsorption is one of the major process used for the removal of Cr(VI) worldwide because it is inexpensive, widely applicable, efficient and creates little amount of sludge(Kannan and Rengasamy, 2005). Chromium can be removed using adsorbents of natural as well as chemical origin. However, these bio-adsorbents have various disadvantages like waste may itself contain various toxicants and subsequently increase the organic content of water. Studies have showed adsorption capacities and applicability for some low-cost materials, among others like alluminium oxide, chitosan, bentonite, saw dust and waste slurry (Dubey and Gopal, 2007). Activated carbon is an effective inexpensive adsorbent which has use in various industries to purify water (D Mohan and Chander, 2001; Yoshihara et al.,2007; Yin et al., 2007).
Bubbles are round because they are ‘minimal surface structures’, which means that bubbles hold the least possible surface area they can. Out of all the geometric shapes, a sphere has the least surface area. Bubble soap is mostly made of water, soap, and glycerin. Glycerin is an organic compound, and its common sources are animal fat and vegetable oil. It is a clear, odorless liquid, and has a sweet taste.
Another chemical, Hydrofluorocarbons (HFCs), having no chlorine atoms which does not bring harm to the ozone layer is considered the best alternative since they are not flammable, such as CF3CH2F,1,1,12 tetrafluoroethane. As CFCs are replaced by HFCs, the remaining CFCS will reduce as the ozone recovers
The mixture is ‘spotted’ at the bottom of the TLC plate and allowed to dry. The plate is placed in a closed vessel containing solvent (the mobile phase) so that the liquid level is below the spot. TLC has advantages over paper chromatography in that its results are more reproducible, and that separations are very efficient because of the much smaller particle size of the stationary phase. The solvent ascends the plate by capillary action, the liquid filling the spaces between the solid particles. This technique is usually done in a closed vessel to ensure that the atmosphere is saturated with solvent vapour and that evaporation from the plate is minimised before the run is complete.
For all adhesives, decontamination of contaminated cured adhesives by “washing and drying” resulted in the lowest bond strength. But, each of the two decontamination procedures, “slow drying” or “washing, drying and reapplication of adhesive,” was acceptable. They related this result to removal of the adhesive layer during washing and drying, leaving a surface that was demineralized but non-infiltrated by monomers. Scanning electron microscopic evaluation also showed minimal resin infiltration on the fractured
Biodiesel is much safer than diesel from petroleum when biodiesel is escaped to the surrounding environment; moreover, it is much less inflammable as biodiesel’s flashpoint is 130°C as compared to petroleum diesel which is only 52°C. As a result, biodiesel is low-risk to be stored, kept, and delivered (U.S Department of Energy). Trans-esterification reaction can be illustrated as following: Triglyceride + Alcohol → Methyl esters (biodiesel) + Glycerol (Vegetable oil) (Methanol) FIGURE 1.1 Typical trans-esterification reaction is carried out to produce Biodiesel (AOCS Lipid Library) Furthermore, biodiesel can be produced from the tobacco seed and soya bean which tobacco seed oil reduces the