Incubation times

which is the same for any applied Kj, after a waiting time that depends on the initial value of Kji. Wei et al. [13] mention non published results obtained by Novak on WOL specimens of 1,260 MPa yield strength steel in sea water at ambient temperature, presented in Fig. 15.15 [13]. The influence of Kj on the incubation time is evident. At Kj — 176 MPa.ym the incubation time is about 300 h that become 1,400 h ( 58 days) if the applied Kj reduces to 147 MPa m and grows to even 3,500 h ( 146 days) under an applied Kj of 88 MPa,ym. It can be thought that the total waiting time preceding the final fracture is composed of 

This is schematically shown in Fig. 15.16. For applied Kj values higher than Kiscc the corrosive process initiates. The higher the applied Kj, the shorter both the incubations time and the growth time 

The upper limit assumed in Fig. 15.16 for the applied Kj is, obviously, that of the static toughness of the material Kje- Once this value is reached brittle fracture is triggered. The lower bound of Kj is Kj cc so that it is Kj cc Kic- When this is the case, Kjsec replaces Kje as the controlling factor for the safety assessment of a structure since SCC is so fast that time to failure cannot be considered in a structural analysis. The ratio of KjscJKjc is, therefore, a measure of toughness reduction caused by SCC. In reality it is not precisely a toughness reduction since Kje remains the same, but rather a substitution of Kje with Kjsec- 

Since SCC is a thermally activated phenomenon, measurements of activation energies from crack growth rate studies. It was found that for high strength steel, even dough the threshold stress intensity factor Kjscc for SCC is similar in both water and hydrogen, the activation energy differs in the two environments. 

At that critical nuclei of the phase 2 are constantly arising at the boundary of the growing phase 1 and B. Taking Equation 3.24 into account, the rate dAxildt for these nuclei is determined by 

The thickness Axi increases, such a moment comes when 

It is quite natural for the time T2 of phase 2 suppression to be referred to as incubation time, if one disregards the time of first critical nuclei formation. 

If D AQ at least approximately fits the Arrhenius dependence ((exp(—Q/feT), for more details see [1]), then the exponential term is given by 

Let us specify the method of calculation of the critical nucleus size. Consider the formation of a phase 1 nucleus at the planar interface a and ff. The formation involves an Gibbs bulk energy gain (decrement) 

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Pyridine herbicides are not strongly sorbed to soils and ate readily leached. The mobiUty of flutoxypyt [69377-81-7] has been found to decrease with increasing incubation time (399) this is attributed to entrapment of the herbicide within the soil organic matter. 

Under certain conditions hydrogen cyanide can polymerize to black soHd compounds, eg, hydrogen cyanide homopolymer [26746-21-4] (1) and hydrogen cyanide tetramer [27027-02-2], C H N (2). There is usually an incubation period before rapid onset of polymer formation. Temperature has an inverse logarithmic effect on the incubation time. Acid stabilizers such as sulfuric and phosphoric acids prevent polymerization. The presence of water reduces the incubation period. 

Tuberculocidal Test. The tubercle bacillus is resistant to disinfectants because the cells are protected with a waxy coating that is not readily penetrated. The tuberculocidal test is a use dilution practical type test that employs porcelain cylinders. The bacteria are different from those in the use dilution method (Table 10), the incubation time is longer, and the details of the procedure are different. For example, in the tuberculocidal test the test is divided into two parts, a presumptive test and a confirmatory test. The former employs Mycobacterium smegmatis and the latter employs Mycobacterium bovis (BCG). For the presumptive test the incubation time is 12 days, as against 48 hours for other bacteria used in the use-dilution method. For the confirmatory test the incubation time is 60 days, with an additional 30 days in case there is no growth. As shown in Table 10, the concentrations of the phenol standard are higher than used with other bacteria. 

The triplet-state energy level of oxytetracycline, the excitation maximum (412 nm), lifetimes of Eu-OxTc (58 p.s) and Eu-OxTc-Cit (158 p.s), were determined. A 25-fold luminescence enhancement at 615 nm occurs upon addition of citrate within a short 5-min incubation time at neutral pH. It s accompanied by a threefold increase of the luminescence decay time. The optimal conditions for determination of OxTc are equal concentrations of Eu(III) and citrate (C = T lO mol-E ), pH 7.2. Eor determination of citrate, the optimal conditions concentrations of Eu(HI) and OxTc are 1 0,5 (Cg = MO Huol-E-i, = 5-10-HuohE-i) at pH 7.2. 

Subsequent investigations proved that identical hydration reactions occur on bare aluminum surfaces and bonded surfaces, but at very different rates of hydration [49]. An Arrhenius plot of incubation times prior to hydration of bare and buried FPL surfaces clearly showed that the hydration process exhibits the same energy of activation ( 82 kJ/mole) regardless of the bare or covered nature of the surface (Fig. 11). On the other hand, the rate of hydration varies dramatically, de-... 

Fig. 11. Arrhenius plot of incubation times prior to hydration of FPL aluminum under various conditions. Adapted from Ref. [49).

Typically, sterol concentrations of 3 to 4 g l 1 are used and incubation times of about lOOh. Yields are dependent upon the species and substrates used. Some data relating to the yields of l,4-androstadiene-3,17-dione from various sterols and steroids using cultures of Arthrobacter simplex are reported in Table 9.3. 

Microbial growth was discovered with replication of each cell to three daughter cells. With the growth data define the mean time for the cell divisions. Table E.10.1 shows the cell dry weight increases with culture incubation time. 

Measure the optical cell density of S. cerevisiae at a wavelength of 520 nm. Try to collect data based on information required in Table 10.1. Draw a growth curve based on incubation time and cell dry weight. The cell concentration is an indication of microorganism growth. A standard calibration curve is needed before any actual experiment. 

Figure 13 shows that the analogous dependence on temperature after longer incubation time at 1 °C becomes nonlinear with higher oligomers. Helix formation starts with n = 6. The ellipticity, depending on the chain lengths at random coil conditions, is shown in Fig. 14. 

To answer the question whether the ds-transisomerization of the bridged polypeptides with a Ala-Gly-Pro sequence represents the rate-determining step, the following experiment was carried out The polypeptide with a chain length n = 8 was denaturated in a rapid reaction with a temperature jump from 9.2 to 30 °C and subjected to renatura-tion at 9.2 °C after an incubation time of 25 s. In a second and a third experiment, the incubation in the coiled state was prolonged respectively to 75 and 125 s. It could be observed that the amplitude of the rapid phase depends on the time that lapses between the denaturation and renaturation (Fig. 32). 

A quantitative interpretation of aldonolactone inhibition in terms of an adaptation of the active site to a transition state approaching a planar, glycosyl oxocarbonium ion is made difficult for several reasons. Due to the interconversion between the 1,4- and 1,5-lactones, and their hydrolysis to the aldonic acids, their use is limited to kinetic studies with incubation times of 10 min or less. This was not realized by most investigators prior to 1970. In many cases, only the 1,4-lactone can be isolated its (partial) conversion into... 

Cherry and Crandall in 1932 (86) used olive oil as substrate with gum acacia as the emufsTfier. This method has served as the basis for a number of modifications that increased the stability of the emulsion, decreased incubation time and gave better precision. When a serum sample is incubated with a stabilized olive oil emulsion, lipase acts at the interface of substrate and water to hydrolyze olive oil into fatty acid plus diglycerides, and to a small extent to monoglycerides and glycerol. The bile salt sodium deoxycholate activates the reaction. These methods measure the liberated fatty acids by titration with a standardized NaOH solution. An indicator such as phenolphatalein, thymolphthalein or methyl red or a pH meter are used to detect the end point. 

The long incubation times of many human virus diseases indicate that they replicate slowly in host cells. In tissue culture systems it has been shown that most human viruses take from 4 to 24 hours to complete a single replication cycle, contrasting with the 30 or so minutes for many bacterial viruses. 

Soil incubation time (weeks) Yield of nitrosoatrazine ( )... 

Figure 4. Digital autoradiogram of supernatants from time-points of Fig. 2. Lanes 1 - 10 = incubation times 0, 5, 15, 20, 30, 45, 60, 90, 120 min. Lane 11 = labelled UDP-Gal as reference.

Enzymatic liquefaction is a relatively new process for the production of juices from fruits and vegetables [1]. Essentially the process is as follows the material is crushed to obtun a pulp which is treated with a combination of pectinases and cellulases. After a certain incubation time, the material becomes a liquid and the Juice can be recovered by decantation. 

Pectin lyase (PNL) activity was measured spectrophotometrically by the increase in absorbance at 235 nm of the 4,5-unsaturated reaction products. Reaction mixtures containing 0.25 ml of culture filtrate, 0.25 ml of distilled water and 2.0 ml of 0.24% pectin from apple (Fluka) in 0.05M tris-HCl buffer (pH 8.0) with ImM CaCl2, were incubated at 37 C for 10 minutes. One unit of enzyme is defined as the amount of enzyme which forms Ipmol of 4,5-unsaturated product per minute under the conditions of the assay. The molar extinction coefficients of the unsaturated products is 5550 M cm [25]. Also viscosity measurements were made using Cannon-Fenske viscometers or Ostwald micro-viscosimeter, at 37°C. Reaction mixtures consisted of enzyme solution and 0.75% pectin in 0.05 M tris-HCl buffer (pH 8.0) with 0.5 mM CaCl2. One unit is defined as the amount of enzyme required to change the inverse specific viscosity by 0.001 min under the conditions of reaction. Specific viscosity (n p) is (t/to)-l, where t is the flow time (sec) of the reaction mixture and t is the flow time of the buffer. The inverse pecific viscosity (n p ) is proportional to the incubation time and the amount of enzyme used [26]. Units of enzyme activity were determined for 10 min of reaction. 

Changes in extracellular esterase activity with incubation time. Esterase activities were assayed using the following methyl esters MCA ( ), MpCA ( ), MSA(a) and MFA (a). 

Davis KER, SJ Joseph, PH Janssen (2005) Effects of growth medium, imoculum size, and incubation time on culturability and isolation of soil bacteria. ZlppZ Environ Microbiol 71 826-835. 

Isolated hepatocytes incubated with ionic iron rapidly undergo lipid peroxidation. Some studies have not shown a consequent decrease in viability (as indicated by uptake of trypan blue or release of enzymes). This is probably a result of short incubation times, as changes in viability lag behind increases in lipid peroxidation, and may not occur for more than 2 h after lipid peroxidation begins (Bacon and Britton, 1990). Recent studies have shown strong correlations between increased lipid peroxidation [production of thiobarbituric acid (TBA) reactants] and loss of cell viability (trypan blue staining) (Bacon and Britton, 1989). The significance of the lag between lipid peroxidation and decreases in cell viability is as yet uncertain. 

Preparation of microtiter plates. A constant amount of the coating antigen is bound to the surface of polystyrene microtiter plate wells by passive adsorption. After a predetermined incubation time, the plate is washed to remove unbound coating antigen. 

Color development too high Incubation too long or Decrease incubation time... 

Classical approaches to plant DNA isolation aim to produce large quantities of highly purified DNA. However, smaller quantities of crudely extracted plant DNA are often acceptable for PCR analysis. Another efficient method for preparation of plant DNA for PCR is a single-step protocol that involves heating a small amount of plant tissue in a simple solution. Several factors influence nucleic acid release from tissue salt, EDTA, pH, incubation time and temperature. These factors must be optimized for different sample substrates. EDTA in the sample solution binds the Mg + cofactor required by the Taq polymerase in the PCR, so the EDTA concentration in the solution, or the Mg + concentration in the PCR, must be carefully optimized. 

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