Slow release control

Artificial heart, artificial muscle, iris, clip for surgery, missile drug Breathing wall, heat-absorbing material Enzyme immobilization, slow release control... 

Slow-Release Fertilizers. Products containing urea—formaldehyde are used to manufacture slow-release fertilisers. These products can be either soHds, Hquid concentrates, orHquid solutions. This market consumes almost 6% of the formaldehyde produced (115) (see Controlled release TECHNOLOGY, AGRICULTURAL). 

Vinyl Phosphates. Dichlorvos [62-73-7] 0,0-dimethyl 0-(2,2-dichloroviayl) phosphate, (CH20)2P(0)0CH=CCl2 (bp 140°C at 27 kPa, d 1.314, vp 1.6 Pa at 20°C), is soluble ia water to about 10 g/L. The half-hfe ia water is 8 h. The rat oral LD qS are 80, 56 mg/kg. Dichlorvos is used ia aerosols and sugar baits to control flies and mosquitoes. Slow release formulations have been used ia plastic strips and pet collars to control animal ectoparasites. 

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

Other. 2-Nitro-1-butanol is an excellent solvent for many polyamide resins, cellulose acetate butyrate, and ethylceUulose. It can be utilized in paint removers for epoxy-based coatings. 2-Hydroxymethyl-2-nitro-l,3-propanediol is usebil for control of odors in chemical toilets. Its slow release of formaldehyde ensures prolonged action to control odor, and there is no reodorant problem which sometimes is associated with the use of free formaldehyde. 2-Hydroxymethyl-2-nitro-l,3-propanediol solutions are effective preservative and embalming fluids. The slow Uberation of formaldehyde permits thorough penetration of the tissues before hardening. 

According to model calculations, the diffusion coefficient plays an Important role in controlling the carbon dioxide concentration in the paint film. Experiments with "slow releasing solvents, meant to influence the diffusion coefficient, confirm this calculated trend. 

The lack of simple and reliable application systems is a major problem to be solved before the introduction of this biocontrol agent into practical control strategies. Mixing fungal chlamydospores into a feed supplement was used in most plot and field studies as an application system (Larsen, 2000). Incorporation into various types of feed blocks or mineral licks, as well as slow-release devices, may also become feasible (Thamsborg et al., 1999 Chandrawathani et al., 2003). 

The current state-of-the-art CBD process for CdS consists of cadmium ions, thiourea, and ammonia. The deposition of a uniform CBD CdS thin film occurs because of a chemical reaction of controlled sulfur and cadmium ions in the alkaline solution. The slow release of sulfur from thiourea via decomposition and slow release of Cd2+ ions from CdfNI I3)2 allow the following chemical reactions ... 

Bailey, D.L., G.C. Labrecque, and T.L. Whitfield. 1970. Slow-release and emulsifiable formulations of Dursban and Abate for controlling larvae of Culex pipiens quinquefasciatus. Mosq. News 30 465-467. 

The transformations of SbClj caused by a one-electron transfer from an aromatic compound have been described earlier. If the pure Lewis acid SbClj is used, its reactivity is very difficult to control, and single-electron oxidation as well as chlorination of various aromatic donors can occur readily (Mori et al. 1998). Meanwhile, in the case of EtjO SbClg", the slow release of the active monomer SbClj occurs. In the case of SbClj as such, the 2SbCl5 — C Sb—CI2—SbCl4 dimerization occurs (Cotton and Wilkinson 1988, p. 395). The dimeric form may lead to the following electrophilic chlorination ... 

Sugar-coated products have been marketed that contain KCl in a wax matrix (Slow-K and Kaon-Ct) and are purportedly slow- and controlled-release preparations. Available evidence indicates that these slow-release forms of KCl are occasionally capable of causing local tissue damage and therefore prol5ably should be used with caution for K+ supplementation. Solutions of potassium gluconate, like the tablets, also have been associated with intestinal ulceration. Microencapsulated KCl preparations Micro-K, K-Dur) that are neither enteric coated nor contained within a wax matrix appear to be superior to the wax matrix formulation. 

C.Y.C. Pak, K. Sakheee, B. Adams-Huet, V. Piziak, R.D. Peterson, J.R. Poindexter, Treatment of postmenopausal osteoporosis with slow-release sodium fluoride Final report of a randomized controlled trial, Ann. Intern. Med. 123 (1995) 401-408. 

A conflict arises from two claims the first, that fluoride stimulates new bone growth and hence is useful therapeutically in controlling osteoporosis, and the other, that it is the cause of the increasing prevalence of hip fractures in the elderly [6]. Fluoride is currently not recommended for the treatment of osteoporosis, although slow release fluoride therapy is reportedly beneficial. The long-term benefit of the latter is unknown [7]. 

Polyelectrolytes have been widely used for the preparation of controlled/sus-tained release of drugs. It is therefore not surprising that attempts have been made to use dental implants for the slow-release of antibiotics and fluorides. It... 

In principle, silica growth kinetics may be controlled by (1) slow release of monomer via alkoxide hydrolysis in the particle-free reverse micelles, (2) slow surface reaction of monomer addition to the growing particle, and (3) slow transport processes as determined by the dynamics of intermicellar mass transfer. There is strong experimental evidence to support the view that the rate of silica growth in the microemulsion environment is controlled by the rate of hydrolysis of TEOS (23,24,29). Silica growth kinetics can be analyzed in terms of the overall hydrolysis and condensation reactions ... 

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