Contact time prolonged

It is well known that exposure of the human body to cryogenic fluids or to surfaces cooled by cryogenic fluids can result in severe cold burns since damage to the skin or tissue is similar to that caused by an ordinary burn. The severity of the burn depends on the contact area and the contact time prolonged contact results in deeper burns. Severe burns are seldom sustained if rapid withdrawal is possible. 

Contact Time. Two factors are involved in considering the contact time. Prolonged contact of acid sludge and oil results in a poorer color and less stability, but too short a time may prevent complete utilization... 

Very recently, Bordiga et al. [99] designed and performed new experiments allowing the collection of FTIR spectra at low temperature and in the presence of CO, which is known to reduce the polymerization speed. Under these conditions, the reduced rate allowed the observation of shorter olygomeric chains [99]. hi Fig. 5 it is evident that, at the lowest reaction times, the v(CH2) peaks were located at 2931 and 2860 cm , i.e., at values distinctly different from those observed in the normal experiments (2920 and 2851 cm ), see Fig. 4. Only after prolonged contact time these new components were overshadowed by the usual bands of the long polymeric chains. In conclusion, these results demonstrate that the study of the reaction in the presence of the... 

Viscous formulations with a high-sucrose content are especially prone to contribute to caries formation because of their prolonged contact time in the oral... 

V f/T enfs - The primary purpose for an ophthalmic ointment vehicle is to prolong drug contact time with the external ocular surface. This is particularly useful for treating children, who may cry out topically applied solutions, and for medicating ocular injuries, such as corneal abrasions, when the eye is to be patched. Administer solutions before ointments. Ointments preclude entry of subseguent drops. 

Most of the readily soluble surface-associated elements may have been depleted in the Drax and Meaford weathered ashes, compared with the fresh ash from Drax, because of their prolonged contact time with water. The Drax ash samples have been deposited 17 years and the Meaford samples some 40 years. Loss of the readily soluble elements from the weathered fly ashes would therefore be anticipated. The results, shown in Table 3, clearly demonstrate that this is the case. The concentrations of Ca, Na, K, SO4-, B, Cr, Cu, Li, Ni, Hg, and Mo are all much lower, with some of the trace elements below the detection limits. The only exception is N03, and the field studies, discussed later, show that fertilizers are probably responsible. 

The duration of action of a local anaesthetic is proportional to the time that the drug remains bound to the sodium channels. Measures that prolong contact time will prolong the duration of the local anaesthetic effect. Cocaine has a vasoconstricting effect on blood vessels and prevents its own absorption. Many local anaesthetics are prepared with adrenaline (epinephrine) in order to achieve this effect. Concentrations are usually of the order of 1 200000 or more dilute than this. Care should be exercised when using adrenaline-containing solutions in the presence of halothane as it is known to sensitise the myocardium to the effects of catecholamines. 

Removes mildew stains and soap scum effectively by prolonging contact time... 

To optimize the formulation vehicles for prolonged drug retention in the precorneal area and increase the contact time between the administered drug and the conjunctival and corneal epithelia by the following methods ... 

Table V summarizes several reactions that have been demonstrated on a laboratory scale 1 know of no industrialized chemical process using Nafion as a superacid catalyst. Although many of the reactions were carried out with stirring a mixture of reactants and Nafion-H, several alkylation, disproportionation, rearrangement, and esterification reactions were performed by means of the flow-reaction method in the liquid or gas phase. For instance, in the esterification of carboxylic acids with alcohols, when a mixture of the acid and alcohol was allowed to flow over a Nafion-H catalyst at 95-125°C with a contact time 5 s, high yields, usually S90%, of the corresponding ester were obtained (82). It had been found that no reactivation of the catalyst was needed because the catalytic activity of the Nafion remained unchanged for prolonged periods of operation.

Loperamide is, therefore, the opioid antidiarrheal of first choice. The prolonged contact time for intestinal contents and mucosa may also improve absorption of fluid. With overdosage, there is a hazard of ileus. The drug is contraindicated in infants below age 2 years. 

In the small intestine, contact time with the absorptive epithelium is limited, and the small intestinel transit time is 3.5-4.5 h [32], The scintographic data show that many prolonged release products, particularly those intended for twice- or once-daily administration, actually release some of their drug contents in the colon where it may be absorbed into the systemic circulation for higher bioavailability. It is anticipated that conditions of dissolution, absorption, and metabolism in the distal portions of the intestine are different than in the proximal regions, due to differences in pH, lumen fluid, mucosal morphology, and motility. 

Various ocular delivery systems, such a ointments, suspensions, micro- and nanocarriers, and liposomes, have been investigated during the past two decades pursuing two main strategies to increase the corneal permeability and to prolong the contact time on the ocular surface [3],... 

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