Toluene penetration

Figure 14.4.1.4. Schematic picture of toluene penetration and efflux in the solvent-tolerant PseurfomonospMftV/a...

It is obvious that solvent tolerance is caused by a combination of the mechanisms described above. Figure 14.4.1.4 shows a schematic picture of toluene penetration and efflux in the solvent tolerant strain P. putida S12. Toluene enters the cell through the outer membrane. At present, it is unclear whether toluene passes through porins or through the phospholipid part of the cell. The efflux piunp recognizes and interacts with toluene in the cytoplasmic membrane. Toluene is then pxunped into the extracellular medium. 

Figure 13.4.1.4. Schematic picture of toluene penetration and efflux in the so tnX-Xo sxaat Pseudomonasputida S12. [Adapted, by permission, from J.A.M. de Bont, Trends Biotechnol, 16,493 (1998).]...

Laminates. Laminate manufacture involves the impregnation of a web with a Hquid phenoHc resin in a dip-coating operation. Solvent type, resin concentration, and viscosity determine the degree of fiber penetration. The treated web is dried in an oven and the resin cures, sometimes to the B-stage (semicured). Final resin content is between 30 and 70%. The dry sheet is cut and stacked, ready for lamination. In the curing step, multilayers of laminate are stacked or laid up in a press and cured at 150—175°C for several hours. The resins are generally low molecular weight resoles, which have been neutralized with the salt removed. Common carrier solvents for the varnish include acetone, alcohol, and toluene. Alkylated phenols such as cresols improve flexibiUty and moisture resistance in the fused products. 

As the name implies, these stains are sprayed on and require Httie if any wiping. The solvent itself penetrates into the pore and allows the pigment and a small amount of binder to remain on the surface. These stains usually are composed of an oil-type vehicle and a combination of earth pigments reduced in a combination of aHphatic and aromatic hydrocarbons such as naphtha and toluene. The solvent system itself plays a big role in the appearance of the stain owing to the varying degrees to which solvents penetrate. Restrictions on the use of certain aromatic hydrocarbons have affected the manner in which these stains work. 

Coal-tar pitches generally soften around 110°C, are about 70 wl% soluble in toluene and 12 wt% insoluble m quinoline. Excessive amounts of primary qumohne insolubles (QI) would contribute to increased carbon yield, but such a pitch may not wet coke well and could hinder the penetration of pitch into the coke voids. 

We have also determined the delivery sites of alkylbenzenes by NMR. As already described in Section III.A, PrBe are deeply transported to the chain tail region in the bilayer core and the delivery site can be classified into category III [46]. Benzene, however, cannot deeply penetrate into the hydrophobic core, zone III, but is trapped preferentially at the interfacial site of the bilayer, zone II the delivery site can be classified into category II. Although benzene is generally considered to be hydrophobic, the delivery site of benzene determined by NMR is reasonable in the sense of the 7r-electrons with some affinity for the hydrophilic sites of the bilayer. Both drug and lipid sides of the H NMR spectra show that alkylbenzenes can deeply penetrate into the bilayer interior in the order PrBe > ethylbenzene > toluene > benzene, which is consistent with the sequence of the insolubility in water. 

For this study, p-xylene and triisopropylcyclohexane (TIPcyC6) were the two molecular probes chosen, using toluene as a solvent. Their molecular dimensions were obtained from the shadow of the three-dimensional molecule projected onto a plane according to the method of Rohrbaurgh et al. [5] (Table 2). A molecular probe is considered not to penetrate into a cylindrical pore if two of its dimensions are greater than the pore diameter [6], As the free diameter of the window of the supercage of the Y zeolite is equal to 0.74 nm, it is considered that only TIPCyC6 cannot penetrate into the zeolite microporosity. 

One synthesis approach that does not rely on CNT formation from the gas phase is molten salt synthesis. The reactor consists of a vertically oriented quartz tube that contains two graphite electrodes (i.e. anode is also the crucible) and is filled with ionic salts (e.g. LiCl or LiBr). An external furnace keeps the temperature at around 600 °C, which leads to the melting of the salt. Upon applying an electric field the ions penetrate and exfoliate the graphite cathode, producing graphene-type sheets that wrap up into CNTs on the cathode surface. Subsequently, the reactor is allowed to cool down, washed with water, and nanocarbon materials are extracted with toluene [83]. This process typically yields 20-30 % MWCNTs of low purity. 

Although the cation-anion interaction of metallocenium ions is very weak, the counteranion is likely to remain in proximity with the metal cation to form a contact ion pair in low-permittivity solvents such as toluene (commonly used in polymerization reactions). If the metal cation allows the counteranion to penetrate into the first coordination sphere, it can form an inner-sphere ion pair (ISIP). When the counteranion is relegated to the second coordinating sphere, the ion pair becomes an outer-sphere ion pair (OSIP), which is more ionic in nature than ISIPs. A schematic representation of the relationship between ISIPs and OSIPs is depicted in Scheme 2. This simple scheme shows us the principal elements that affect the cation-anion interactions (e.g., counteranion (Y ), ancillary ligands (L ), transition metal (M), and alkyl ligand (R)), and the subtle balance between these elements in the dynamic equilibria. 

Since no data are available on humans except for skin penetration data in vitro, no direct comparison can be made. Because in humans most of the dose seems to be excreted as hippurate (lARC, 1986) and because the metabolism of the primary hydrolysis product of benzyl acetate, benzyl alcohol, is very similar in rodents and humans (see, e.g., the monograph on toluene (this volume)), it is to be expected that the fate of benzyl acetate in humans is very similar to that in rodents. 

The emission from the radioisotopes is often insufficient to penetrate the window of a Geiger-Muller counter. Therefore, the compound whose activity is to be measured is often mixed in solution with a scintillator, called a fluor, which transforms / rays into luminescence proportional to the number of /3 particles emitted. The sample is dissolved in a solvent (toluene, xylene or dioxane, the latter being used for water-soluble compounds) that acts as a relay to transfer the energy to the scintillator. The scintillation mixture contains PPO (2,5-diphenyloxazole), which emits in the UV and POPOP, which emits in the visible and is well adapted to detection with photomultiplier tubes (Fig. 17.2). The quantum yield of emission will depend on the energy of the emitted particles. 

Of the hydrocarbons toluene is the only one which nitrates sufficiently easily and yields a product which has the proper physical and explosive properties. Trinitrotoluene is the most widely used of the pure aromatic nitro compounds. It melts at such temperature that it can be loaded by pouring. It is easily and surely detonated, and is insensitive to shock, though not insensitive enough to penetrate armor-plate without exploding until afterwards. It is powerful and brisant, but less so than trinitrobenzene which would offer certain advantages if it could be procured in sufficient quantity. 

Surfactants disrupt the cell wall by solubilizing the lipids in the wall. Sodium dodecylsulfate (SDS), sodium sulfonate, Triton X-100, and sodium taurocholate are examples of the surfactants often employed in the laboratory. Alkali treatment disrupts the cell walls in a number of ways including the saponification of lipids. Alkali treatment is inexpensive and effective, but it is so harsh that it may denature the protein products. Organic solvents such as toluene can also rupture the cell wall by penetrating the cell wall lipids, swelling the wall. When red blood cells or a number of other animal cells are dumped into pure water, the cells can swell and burst due to the osmotic flow of water into the cells. 

Melanin compounds may appear brown, black, or red. The type of melanin determines hair color, and the density of melanin granules determines the shade. Dark shades of dyed hair contain higher concentrations of dyes. Most hair colors are combinations of organic compounds chosen to produce particular shades. Resorcinol produces a yellow color aminohydroxy-toluene produces a redder hair, and nitrophenylenediamine dye results in very red hair. Graded dyes favored by men often contain lead acetate. The lead ions penetrate into hair and form lead sulfide (PbS), a dark-colored compound. 

Jahnisch et al. used an IMM falling-film microreactor for photochlorination of toluene-2,4-diisocyanate [38] (see also Chapter 4.4.3.3, page 161). As a result of efficient mass transfer and photon penetration, chlorine radicals were well distributed throughout the entire film volume, improving selectivity (side chain versus aromatic ring chlorination by radical versus electrophilic mechanism) and spacetime-based yields of l-chloromethyl-2,4-diisocyanatobenzene compared to those obtained using a conventional batch reactor. 

Aromatic plant material is placed into organic solvents such as acetone (propanone) or hexane, which dissolve out the oils. Other solvents used are methanol, ethanol, toluene and petroleum ether. In some processes the plant material is broken up, to aid penetration of solvent into the tissues, by placing it in a rotating drum with internal blades to ensure thorough mixing. The materials that become dissolved include not only the essential oil but also natural waxes, resinous materials, chlorophyll and other pigments. 

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