Infusion process, chemical

Rather than an in-depth technical description of the mechanics of extraction, this section presents briefly a typical infusion process, focusing on the factors that make extracts different from single-chemical components. Extracts by then nature are complex mixtures of (often) diverse active compounds contained within a plant matrix which are brought into solution by the extraction process. The aim of the extractor is to produce, over a period of time, batches of an extract meeting a customer s individual specification with as little variation as possible. There are parameters over which the extractor has some control, and these can be used to help achieve product consistency and also to fine-tune an extract to a particular customer s needs. 

The chemical infusion process was first developed to smooth the surfaces of PMMA rod for use as mandrels for physical vapor deposition of thin metal foils. This technique requires selection of an appropriate solvent for the polymer to act as the solvent component. A second solvent is chosen as a poor solvent for the polymer and will be referred to as the non-solvent component. The non-solvent component must be miscible with the solvent and any additives must be initially soluble in the solvent/non-solvent mixture. This starting solution causes the polymer matrix to swell and, thereby, facilitates the diffusion of the insoluble additives into the treated sector. As the infusion process proceeds, the initial solution is gradually replaced with the non-solvent mixture until the solution consists of greater than 95% diluent. During this latter phase of the process, the solvent diffuses out of the polymer, which results in the restoration of the polymer s surface rigidity. At the end of the process, the polymer samples are removed from the bath, rinsed with the non-solvent to remove additives adsorbed on the surface, and allowed to dry. 

Figure 4. Three PMMA disks after treatment by the chemical infusion process with 35% PVP and (a) 0, (b) 5, and (c) 50% titanium (IV) isopropoxide in the diluent solution.

The chemical infusion process can modify a significant fraction (-38%) of the treated region and the surface of PMMA as indicated in the cell adherence assay. This was elucidated by the detection of titanium in... 

The sterile peritoneal dialysis solutions are infused continuously into the abdominal cavity, bathing the peritoneum, and are then continuously withdrawn. The purpose of peritoneal dialysis is to remove toxic substances from the body or to aid and accelerate the excretion function normal to the kidneys. The process is employed to counteract some forms of drug or chemical toxicity as well as to treat acute renal insufficiency. Peritoneal dialysis solutions contain glucose and have an ionic content similar to normal extracellular fluid. Toxins and metabolites diffuse into the circulating dialysis... 

Parent (unsubstituted) PF was first synthesized electrochemically by anodic oxidation of fluorene in 1985 [266] and electrochemical polymerization of various 9-substituted fluorenes was studied in detail later [220,267]. Cyclic voltammogram of fluorene ( r1ed= 1.33 V, Eox = 1.75 V vs. Ag/Ag+ in acetonitrile [267]) with repetitive scanning between 0 and 1.35 V showed the growth of electroactive PF film on the electrode with an onset of the p-doping process at 0.5 V (vs. Ag/Ag+). The unsubstituted PF was an insoluble and infusible material and was only studied as a possible material for modification of electrochemical electrodes. For this reason, it is of little interest for electronic or optical applications, limiting the discussion below to the chemically prepared 9-substituted PFs. 

Statistical copolymerization of ethylene glycol and 1,4-butanediol with dimethyl ter-ephthalate results in products with improved crystallization and processing rates compared to poly(ethylene terephthalate). Polyarylates (trade names Ardel, Arylon, Durel), copolymers of bisphenol A with iso- and terephthalate units, combine the toughness, clarity, and proce-sibility of polycarbonate with the chemical and heat resistance of poly(ethylene terephthalate). The homopolymer containing only terephthalate units is crystalline, insoluble, sometimes infusible, and difficult to process. The more useful copolymers, containing both tere- and isophthalate units, are amorphous, clear, and easy to process. Polyarylates are used in automotive and appliance hardware and printed-circuit boards. Similar considerations in the copolymerization of iso- and terephthalates with 1,4-cyclohexanedimethanol or hexa-methylene diamine yield clear, amorphous, easy-to-process copolyesters or copolyamides,... 

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