Rapid injection

The catalysts are primarily DCPD-soluble derivatives of tungsten and molybdenum and the activators are aluminum alkyls (63—64). Polymerization is accompHshed by mixing equal amounts of Hquid DCPD (at >32° C), one part of which contains the catalyst and the other of which contains the activator. The mixture is rapidly injected into a mold, where the polymerization takes place. Polymerization times are from under 30 seconds to several minutes, depending on the size of the part, mold temperature, and modifiers added to the polymerizate. 

The foam effect is achieved by the dispersion of inert gas throughout the molten resin directly before moulding. Introduction of the gas is usually carried out by pre-blending the resin with a chemical blowing agent which releases gas when heated, or by direct injection of the gas (usually nitrogen). When the compressed gas/resin mixture is rapidly injected into the mould cavity, the gas expands explosively and forces the material into all parts of the mould. An internal cellular structure is thus formed within a solid skin. 

When the compressed gas/resin mixture is rapidly injected into the mould cavity, the gas expands explosively and forces the material into all parts of the mould. 

Fig. 3.3.3 Effects of temperature on the activities of luciferase ( ) and the quantum yields of coelenterazine (o) in the Oplophorus bioluminescence reaction. The activity was measured with coelenterazine (4.5 pg) and luciferase (0.05 pg), and the quantum yields with coelenterazine (0.2 pg) and luciferase (200 pg), in 5 ml of 15 mM Tris-HC1 buffer, pH 8.3 (at 25°C), containing 50 mM NaCl. Coelenterazine was first added to the buffer solution at the designated temperature, then the luminescence reaction was started by a rapid injection of 0.1 ml of luciferase solution. Replotted from Shimomura et al., 1978, with permission from the American Chemical Society.

Research studies over the past several years have shown that least three possible methods exist for terminating propellant combustion—rapid depressurization of the combustion chamber, the L method, and rapid injection of a vaporizable fluid. Each of these methods initiates pressure and temperature disturbances within the combustion zone which disrupt the balance between the rate of heat generation by chemical reactions and the rate of heat loss. If the disturbances cause the heat loss to exceed the heat input, combustion will be extinguished. These three methods for achieving termination merely differ in the mechanism by which the pressure and temperature disturbances are created. 

Experimental determination of the density function requires rapid injection of tracer molecules at the inlet to the system. Ideally, a finite number of molecules will be injected in an infinitesimal period of time. Think of quick injection using a syringe. 

Use of water sprays or very rapid injection of suppressant gas or powder. 

Figure 39.4a represents schematically the intravenous administration of a dose D into a central compartment from which the amount of drug Xp is eliminated with a transfer constant kp. (The subscript p refers to plasma, which is most often used as the central compartment and which exchanges a substance with all other compartments.) We assume that mixing with blood of the dose D, which is rapidly injected into a vein, is almost instantaneous. By taking blood samples at regular time intervals one can determine the time course of the plasma concentration Cp in the central compartment. This is also illustrated in Fig. 39.4b. The initial concentration Cp(0) at the time of injection can be determined by extrapolation (as will be indicated below). The elimination pool is a hypothetical compartment in which the excreted drug is collected. At any time the amount excreted must be equal to the initial dose D minus the content of the plasma compartment Xp, hence ...

Figure 12. An example of use of to assess the rate and depth of sediment mixing from a core on the slopes of the Bahamas (Henderson et al. 1999b). The exponential decrease in Pbxs seen in the upper 6 cm of the sediment reflects decay of °Pb as it is mixed downward. The diffusional model of mixing described in the text indicates a mixing rate, D, of 51 cm kyr for this core. The two circled points at greater depth reflect rapid injection of surface material to depth in a process known as conveyor-belt feeding (Robbins 1988 Smith et al. 1997).

Hot needle or solvent flush method. Rapid injection. Reproduce injection time as close as possible. 

Acids are sometimes used ahead of fracturing fluids to dissolve mineral fine particles and allow more rapid injection of the fracturing fluid. When used as the initial stage of a squeeze cementing treatment, the acid-promoted mineral and drilling mud particle dissolution can result in increased entry of the cement slurry into the desired portions of the formation. 

Levenspiel and Smith Chem. Eng. Sci., 6 (227), 1957] have reported the data below for a residence time experiment involving a length of 2.85 cm diameter pyrex tubing. A volume of KMn04 solution that would fill 2.54 cm of the tube was rapidly injected into a water stream with a linear velocity of 35.7 cm/sec. A photoelectric cell 2.74 m downstream from the injection point is used to monitor the local KMn04 concentration. Use slope, variance, and maximum concentration approaches to determine the dispersion parameter. What is the mean residence time of the fluid ... 

Perhaps the simplest solvent dispersion method is that developed by Batzri and Korn (1973). Phospholipids and other lipids to be a part of the liposomal membrane are first dissolved in ethanol. This ethanolic solution then is rapidly injected into an aqueous solution of 0.16M KC1 using a syringe, resulting in a maximum concentration of no more than 7.5 percent ethanol. Using this method, single bilayer liposomes of about 25 nm diameter can be created that are... 

Volatilised tin species were trapped from the same or replicate water samples following rapid injection of aqueous, excess sodium borohydride solution directly into the P/T sparging vessel immediately prior to beginning the P/T cycle. 

Levenspiel and Smith (1957) conducted an experiment with a 2.85cm diameter (internal) tube. 16.2 cm3 of a solution of KMnC>4 was rapidly injected into a water stream which flowed through the tube at a velocity of 0.357 m s-1. A photoelectric cell positioned 2.75 m downstream from the injection point was used to monitor the effluent concentration (cKMn04) from the tube. Determine, using the data given below,... 

Possibility that rapid injection rates may cause severe adverse reactions. 

Arnett and coworkers later examined the reaction of lithium pinacolone enoiate with substituted benzaldehydes in THE at 25 °C. The determination of the heat of reaction indicated that the Hammett p value for the process is 331. Although the aldol reaction was instantaneous in THF at 25 °C, the reaction with o- or p-methylbenzaldehyde could be followed using a rapid injection NMR method in methylcyclohexane solvent at —80 °C. Application of Eberson s criterion based on the Marcus equation, which relates the free energy of ET determined electrochemically and the free energy of activation determined by kinetics, revealed that the barriers for the ET mechanism should be unacceptably high. They concluded that the reaction proceeds via the polar mechanism . Consistent with the polar mechanism, cyclizable probe experiments were negative . The mechanistic discrepancy between the reactions of benzaldehyde and benzophenone was later solved by carbon kinetic isotope effect study vide infraf. ... 

Neonates and children (younger than 2 years of age) - Rapid injection (10 mL/min) of hypertonic sodium bicarbonate solutions may produce hypernatremia, a decrease in cerebrospinal fluid pressure and possible intracranial hemorrhage. Do not administer more than 8 mEq/kg/day. A 4.2% solution is preferred for such slow administration. 

Ofofox/c/fy. Tinnitus, reversible and irreversible hearing impairment, deafness, and vertigo with a sense of fullness in the ears have been reported. Deafness is usually reversible and of short duration (1 to 24 hours) however, irreversible hearing impairment has occurred. Usually, ototoxicity is associated with rapid injection, with severe renal impairment, with doses several times the usual dose, and with concurrent use with other ototoxic drugs. 

Cardiac effects Cardiorespiratory arrest or anaphylaxis has occurred, possibly because of excessively rapid administration in some cases. Rapid injection of undiluted miconazole may produce transient tachycardia or arrhythmia. 

Moertel CG, Schutt AJ, Reitemeier RJ, et al. A comparison of 5-fluorouracil administered by slow infusion and rapid injection. Cancer Res 1972 32 2717-2719. 

Assume that 1.0 x 10-3 mol of sodium naphthalene is dissolved in tetrahydrofuran and then 2.0 mol of styrene is introduced into the system by a rapid injection technique. The final total volume of the solution is 1 liter. Assume that the injection of styrene results in instantaneous homogeneous mixing. It is found that half of the monomer is polymerized in 2000 s. Calculate the propagation rate constant. Calculate the degree of polymerization at 2000 and at 4000 s of reaction time. 

RTD studies were carried out by Jagadeesh and Satyanarayana (lEC/PDD 11 520, 1972) in a tubular reactor (L = 1.21 m, 35 mm ID). A squirt of NaCl solution (5 N) was rapidly injected at the reactor entrance, and mixing cup measurements were taken at the exit. From the following results calculate the vessel dispersion number also the fraction of reactor volume taken up by the baffles. 

Cisplatin (dx-Diamminedichloroplatinum) is a divalent water-soluble platinum containing complex. It reacts directly with DNA, resulting in both intra-and inter-strand cross-links. It also causes DNA breaks and it inhibits DNA replication and RNA transcription. A mechanism for the occurrence of resistance appears to be an increased of the levels of DNA-excision repair enzymes. Cisplatin is used in combination therapies with other anticancer drugs in the treatment of testicular and ovarian cancers and it has also shown high activity against cancers of the bladder, head, neck and endometrium. It is administered intravenously by rapid injection or by continuous infusion. It is for more that 90% bound to... 

Red-neck" syndrome (redness on face, neck, arms, and back chills fever tachycardia nausea or vomiting pruritus rash unpleasant taste) may result from too-rapid injection. 

Diazoxide is similar chemically to the thiazide diuretics but has no diuretic activity. It is bound extensively to serum albumin and to vascular tissue. Diazoxide is partially metabolized its metabolic pathways are not well characterized. The remainder is excreted unchanged. Its half-life is approximately 24 hours, but the relationship between blood concentration and hypotensive action is not well established. The blood pressure-lowering effect after a rapid injection is established within 5 minutes and lasts for 4-12 hours. 

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