Leachable material

Acid aqueous solution, % by mass Powder liquid, g cm Setting time, minutes Compressive strength (24 hour), MPa Water-leachable material," % mass... 

Water-leachable material 7 minute cure, % mass 0-88 2-1 0-74 1-25... 

Water-leachable material 1 hour cure, % mass 0-40 0-45 0-46 0-70... 

Y-intercept and the slope, respectively, and are listed in Table I. The results of the dissolution rate determination method (method 2) are presented in Figure 3. As can be seen, the maximum removable mineral (P0) by dilute acid is independent of the size of the shale particles. However, the carbonate fraction in the shale mineral matrix is very close to this figure. This could mean that the accessibility of the leaching agent to the leachable materials in shale is complete in the size ranges studied in this experiment—but at different rates. This could also indicate that the carbonate deposit sites are not isolated but can, perhaps, be thought of as interconnected by minerals built of the dilute acid-resistant minerals. 

The adsorbent used in this study is Filtrasorb 400 activated carbon obtained from Calgon Corporation, Pittsburg, Pennsylvania. The adsorbent was sieved and the size fraction 30/35 mesh -particles passing 30 mesh sieve and retained on a 35 mesh sieve -was used in all rate studies. Adsorption equilibrium is independent of particle size, and equilibrium data were obtained with both 30/35 and 60/100 mesh size fractions. The carbon was washed in distilled water to remove fines and leachable material and dried to constant weight at 105°C prior to use. 

The higher viscosity of semisolid dosage forms and transdermal systems may cause the rate of migration of leachable substances into these dosage forms to be slower than for aqueous solutions. Due to extended contact, the amount of leach-ables in these drug products may depend more on a leachable material s affinity for the liquid/semisolid phase than on the rate of migration. 

Extractables and Leachables — Materials or components derived from the container and closure that have been transferred into the contained drag substance or drug product. Forced Degradation Testing Studies [ICH Q1B] — Studies undertaken to degrade the sample deliberately. These studies, which may be undertaken in the development phase normally on the drug substances, are used to evaluate the overall photosensitivity of the material for method development purposes or degradation pathway elucidation. 

Landfills are simply buried containers designed to hold solid wastes while at the same time preventing waste materials from having a negative environmental impact. Such precautions are necessary, especially if land reuse for alternate purposes is a key issue. Consequently, it is best to regard a landfill site as merely a temporary disposal facility. For example, if the contents of a landfill site present an environmental contamination problem, they may have to be either relocated or rendered environmentally neutral (i.e., having no residual biodegradable oil and no residual content of leachable material). 

In these tests, the form and area of the material, the thickness, and the surface area to extraction vehicle volume are critical considerations in the testing protocol. Appropriate extraction vehicles, that is, solvents, should be chosen to yield a maximum extraction of leachable materials to conduct the testing. Mice, rats, or rabbits are the usual animals of choice for the conduct of these tests and depending on the intended application of the biomaterial, oral, dermal, inhalation, intravenous, intraperitoneal, or subcutaneous application of the test substance may be used. Acute toxicity is considered to be the adverse effects that occur after administration of a single dose or multiple doses of a test sample given within 24 h. Subacute toxicity (repeat dose toxicity) focuses on adverse effects occurring after administration of a single dose or multiple doses of a... 

The best method for protecting soils from heavy metal contamination is prevention. It is very expensive and difficult to clean contaminated sods. Some treatments include high temperature methods to produce a non-leachable material, solidifying agents to make cement-like material, and a washing process to remove contaminants. Several other techniques involve soil and crop management by adjusting the pH of the soil and the use of plants to remove metals from soil and water. 

Over the past two decades, DMA has proven to be a useful technique for the characterisation of biomaterials since it not only gives a quantitative assessment of material properties such as stiffness and damping, but also provides structural information. This is because the dynamic mechanical properties of materials are sensitive to aU kinds of transitions, relaxation processes, structural heterogeneity and morphology of multi-phase systems such as crystalline polymers, polyblends and composites. DMA can also pinpoint thermal transitions for example, typical output of tan 8 versus temperature will display a peak at Tg. Above 7, peaks correspond to the crystalline regions and eventually Tm. As a technique, DMA is also sensitive for the characterisation of polymers of similar chemical compositions, as well as detecting the presence of moderate quantities of additives such as plasticisers or leachable materials. For example, PVC is very stiff, however, with the addition of plasticisers it can be made more flexible. 

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

Flange face areas experience stagnant conditions. Additionally, some gasket materials, such as asbestos fiber, contain leachable chloride ions. This creates crevice and stress corrosion cracking problems on sealing surfaces. Where necessary, flange faces that are at risk can be overlaid with nickel-based alloys. Alternatively, compressed asbestos fiber gaskets shrouded in PTFE may be used. 

Wilson, A. D. (1975c). Dental cements based on ion-leachable glasses. In von Fraunhofer, J. A. (ed.) Scientific Aspects of Dental Materials, Chapter 6. London and Boston Butterworths. 

Speciated Components Little information is available for RMs with respect to the chemical forms or species in which elements occur. In the first approximation, bioavaila-ble, extractable, or leachable levels of elements are of interest. Secondly, at a higher degree of sophistication, data on the levels of the actual species or inorganic moieties such as nitrate, ammonium, phosphate, bromide, bromate, iodide, iodate, and molecular species of which the elements are constituents would be of relevance to those conducting mechanistic and speciation research. Reference materials that are certified for extractable elemental concentrations are not available to monitor the usual procedures in soil science based on extraction. 

As to the analysis of trace elements in paper, cardboard and raw materials for the production of paper, high concentration elements such as Cu, Fe or Ti can easily be determined by FAAS Cd and Pb are frequently analysed by GFAAS. Cadmium in pulp and paper was determined by AAS after pressurised digestion with nitric acid [145]. An interlaboratory comparison of Cd in wrapping paper was reported, mainly based on pressure digestion in FIFE bombs with sub-boiled nitric acid, followed by ETAAS [59]. For wrapping paper used for foodstuffs, next to the total content of toxic heavy metals, the soluble or leachable fraction is of particular interest. 

Container size and physical design the concentration of materials leachable from glass decreases with increasing container size. The concentration of leached materials will increase with increasing surface-to-volume ratio for a given container size. In containers treated by the glass manufacturer, this extraction process can be significantly retarded [5]. 

Brixie JM, Boyd SA (1994) Treatment of contaminated soils with organoclays to reduce leachable pentachlorophenol. J Environ Qual 23 1283-1290 Brown MJ, Burris DR (1996) Enhanced organic contaminant sorption on soil treated with cationic surfactants. Ground Water 34 734-744 Burris DR, Antworth CP (1992) In situ modification of an aquifer material by a cationic surfactant to enhance retardation of organic contaminants. J Contam Hydrol 10 325-337... 

High temperature processes produce a slag, a non-leachable, non-hazardous material suitable for use as construction materials. most cases. 

Plasma gasification is a generic-type process that can accommodate virtually any input waste material in as-received condition, including liquids, gases, and solids in any form or combination. Also, moisture content is not a problem. Liquids, gases, and small particle-size waste materials are very easily and efficiently processed. Bulky items, such as household appliances, tires, and bedsprings, can also be readily accommodated without loss of destruction efficiency. The reactor vessel and waste feed mechanism are designed for the physical characteristics of the input waste stream. Even waste materials such as low-level radioactive waste can be processed to reduce the bulk and encapsulate the radioactive constituents to reduce leachability. 

Unlike glass-ionomers or compomers, composite resins are not inherently fluoride-releasing and they do not generally contain any fluoride compounds. However, they can be formulated with such compounds [281], for example NaF, YbFs or ion-leachable glass [201]. Organic fluorides can be used, too, such as methacryloyl fluoride-methyl methacrylate (MF-MMA) or tetrabutyl ammonium tetrafluoroborate. These latter substances impart the property of slow release of fluoride to the surrounding tissue without the creation of voids within the material. 

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