Extraction, direct

For combustible dusts, the explosibility limits do not have the same meaning as with flammable gases and flammable vapors, owing to the interaction between dust layers and suspended dust. This protective measure can, for example, be used when dust deposits are avoided in operating areas or in the air stream of clean air lines after filter installations WTiere in normal operation the lower explosibility limit is not reached. However, dust deposits must be anticipated with time. When these dust deposits are whirled up in the air, an explosion hazard can arise. Such a hazard can be avoided by regular cleaning. The dust can be extracted directly at its point of origin by suitable ventilation measures. 

For modern derrick and mast designs, API Standard 4F is the authoritative source of information, and much of this section is extracted directly from this standard. Drilling and well servicing structures that meet the requirements of API Standard 4F are identified by a nameplate securely affixed to the structure in a conspicuous place. The nameplate markings convey at least the following information ... 

In Fig. 42.9 we show the simulation results obtained by Janse [8] for a municipal laboratory for the quality assurance of drinking water. Simulated delays are in good agreement with the real delays in the laboratory. Unfortunately, the development of this simulation model took several man years which is prohibitive for a widespread application. Therefore one needs a simulator (or empty shell) with predefined objects and rules by which a laboratory manager would be capable to develop a specific model of his laboratory. Ideally such a simulator should be linked to or be integrated with the laboratory information management system in order to extract directly the attribute values. 

In a study on the identification of organic additives in rubber vulcanisates using mass spectrometry, Lattimer et al. [22] used direct thermal desorption with three different ionisation methods El, Cl and FI. Also, rubber extracts were examinated directly by four ionisation methods (El, Cl, FD and FAB). The authors did not report a clear advantage for direct analysis as compared to analysis after extraction. Direct analysis was a little faster, but the extraction methods were considered to be more versatile. 

Fresh leaves of rue were collected from the plants grown in the Botanical Garden, Naples. Two hundreds grams (fresh weight) of leaves were extracted directly by dipping them for 10 min in 1 litre of hot water (95°C). The resulting infusion was subsequently used for the germination experiments. 

Despite the undoubted advantages of recombinant production, it remains the case that many protein-based products extracted directly from native source material remain on the market. In certain circumstances, direct extraction of native source material can prove equally/more attractive than recombinant production. This may be for an economic reason if, for example, the protein is produced in very large quantities by the native source and is easy to extract/purify, e.g. human serum albumin (HSA Chapter 12). Also, some blood factor preparations purified from donor blood actually contain several different blood factors and, hence, can be used to treat several haemophilia patient types. Recombinant blood factor preparations, on the other hand, contain but a single blood factor and, hence, can be used to treat only one haemophilia type (Chapter 12). 

Proteins produced by recombinant DNA technology are usually purified by means identical to those available for purification of traditional non-recombinant proteins extracted directly from... 

Cocaine can be extracted from the leaves with almost any organic solvent. Moisten the dried, powdered leaves with Na carbonate solution and extract with cold benzene or petroleum ether. Extract the organic solution with small amounts of dilute sulfuric acid and basify the extract with Na carbonate (the alkaloids precipitate). Dissolve the precipitate in ether, separate the ether from the aqueous Na carbonate and dry and evaporate in vacuum the ether. Dissolve the residue in methanol and heat with sulfuric acid or methanol-HCl dilute with water and extract with CHC13. Concentrate and neutralize the aqueous layer and cool to precipitate methylecgonine sulfate, which is converted to cocaine in one step. The alkaloids can also be extracted directly from the powder with dilute sulfuric acid. 

Hcxanc can be determined in biological fluids and tissues and breath using a variety of analytical methods. Representative methods are summarized in Table 6-1. Most methods utilize gas chromatographic (GC) techniques for determination of -hexane. The three methods used for preparation of biological fluids and tissues for analysis are solvent extraction, direct aqueous injection, and headspace extraction. Breath samples are usually collected on adsorbent traps or in sampling bags or canisters prior to analysis by GC. 

Lipids from liquid samples or cell suspensions may be extracted directly into organic solvents but solid samples will require prior treatment, such as homogenization or ultrasonication. The solvents are chosen with reference to the nature of the lipids present and to some extent, the type of sample, e.g. animal or vegetable tissue. Ethanol-diethyl ether (3 1) with subsequent extraction... 

Some industrial operations involving bubble and drop formation are extraction, direct contact heat exchange, distillation, absorption, sparger reactors, spray drying and atomization, fluidization, nucleate boiling, air lifts, and flotation. 

The thermochemical data for the chemical compounds that follow in this appendix are extracted directly from the JANAF tables [ JANAF thermochemical tables, 3rd Ed., Chase, M. W., Jr., Davies, C. A., Davies, J. R., Jr., Fulrip, D. J., McDonald, R. A., and Syverud, A. N.,./. Phys. Chem. Ref. Data 14, Suppl. 1 (1985)]. The compounds chosen from the numerous ones given are those believed to be most frequently used and those required to solve some of the problem sets given in Chapter 1. Since SI units have been used in the JANAF tables, these units were chosen as the standard throughout. Conversion to cgs units is readily accomplished by use of the conversion factors in this appendix (Table Al). Table A2 contains the thermochemical data. 

For semivolatile constituents of petrolenm, the gas chromatograph is generally eqnipped with either a packed or a capillary colnmn. Either neat or dilnted organic liqnids can be analyzed via direct injection, and componnds are separated dnring movement down the column. The flame ionization detector nses a hydrogen-fneled flame to ionize compounds that reach the detector. For PAHs a method is available (EPA 8100) in which injection of sample extracts directly onto the colnmn is the preferred method for sample introdnction for this packed-colnmn method. 

Cloud point extraction of metal ions. The use of cloud point extraction as a separation technique was first introduced by Watanabe for the extraction of metal ions forming sparingly water soluble complexes [109], Since then, the technique has been applied successfully to the extraction of metal chelates for spectrophotometric, atomic absorption, or flow injection analysis of trace metals in a variety of samples [105-107,110]. Other metal complexes such as AUCI4 or thiocyanato-metal complexes can be extracted directly using nonionic surfactants such as polyoxyethylene... 

Bromine is the 62nd most abundant element found on Earth. Although it is not found uncombined in nature, it is widely distributed over the Earth in low concentrations. It is found in seawater at a concentration of 65 ppm. This concentration is too low for the bromine to be extracted directly, so the salt water must be concentrated, along with chlorine and other salts, by solar evaporation, distillation, or both. 

Sugar cane wax is an interesting by-product of the sugar industry and one which has for the most part been neglected. It occurs in the so-called factory mud, which is usually discarded. It has been shown, however, that extraction of the wax is possible and that the product can be resolved into a fatty substance and a wax proper. The mud is extracted with benzene and the crude wax resolved into a pure wax and a fatty portion which is soluble in cold acetone. Indian workers have preferred to use an initial extraction with petroleum ether and to purify the extract by treatment with nitric acid. Alternatively the wax may be extracted directly from the expressed juice before the latter is processed for sucrose manufacture. The wax is of good quality approaching that... 

While these steroids can be extracted directly from human tissue, in most instances they can also be synthesized chemically. Direct chemical synthesis methodology has also facilitated the development of synthetic steroid analogues. Many such analogues exhibit therapeutic advantages over the native hormone, e.g. they may be more potent, be absorbed intact from the digestive tract, or exhibit a longer duration of action in the body. The majority of sex steroid hormones now used clinically are chemically synthesized. 

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