Specific activity, calculation

For a series of silica-supported metals, the specific activity, calculated as the rate coefficient at 100° C referred to unit area of metal, has been found [155] to decrease in the order Pd > Rh > Pt > Ni > Co > Ru > Ir Fe, Os = 0. For pumice-supported metals, the corresponding... 

The final protein content of the solution is 2.8 mg/ml. The solution has 7 U/ml of specific activity, calculated using azocasein as substrate (see Basic Protocol 2, steps 1 to 8). All enzymes are available from Sigma. 

Nafion SAC-13 exhibited the highest specific activity calculated by taking into account the number of acidic sites. 

In the fourth experiment incorporation of intermolecularly doubly labeled phenylalanine (at carboxyl carbon and at the / carbon of the side chain) was investigated. The labeled decodine and decinine contained radioactivity only at the expected four carbon atoms C-l, C-3, C-l 1, and C-13 which were isolated and assayed for radioactivity. The ratios of relative specific activities calculated from these data (C-3/C-1, C-11/C-l3) were in good agreement with the activity ratio of the precursor (C02H// -CH2). 

Purification level. This parameter is a measure of the increase in purity and is obtained by dividing the specific activity, calculated after each purification step, by the specific activity of the initial extract. 

From the results of Figure 4a, it can be seen that different contact time are necessary to achieved similar ethane conversion. Thus, it can be concluded that the activity, per gram of catalyst, decreases in the following trend V/MgO > VAPO-5 > MgVAPO-5. However, when the specific activities, calculated per vanadium atom, are considered, it can be seen that the activity of vanadium atoms decrease in the trend VAPO-5 > MgVAPO-5 > V/MgO. 

It may be appropriate to use less substrate when trying to detect very low levels of ATase since less substrate will produce lower background counts. It is important that ATase specific activity calculations are based on the linear part of the protein dependence curves. 

Oxidation of methane on ceria has been studied by C. Bozo [44]. Ceria prepared by a precipitation method developed a BET area of 80 mVg after 500°C calcination and only ImVg when treated at 1000°C. Specific activities calculated at 500°C and 700 C were found to be IS.IO mol(CH4).h m- and 5.10 mol(CH4).h-... 

Specific activity calculation based on molar extinction coefficient of 14o7Xl(P for AMP at 257nm. Fraction contains 10% xanthine. Rechromatographed inosine was free of xanthine. 

Tajima and co-workers [108] determined the surface excess of sodium dode-cyl sulfate by means of the radioactivity method, using tritiated surfactant of specific activity 9.16 Ci/mol. The area of solution exposed to the detector was 37.50 cm. In a particular experiment, it was found that with 1.0 x 10" Af surfactant the surface count rate was 17.0 x 10 counts per minute. Separate calibration showed that of this count was 14.5 X 10 came from underlying solution, the rest being surface excess. It was also determined that the counting efficiency for surface material was 1.1%. Calculate F for this solution. 

If both frequency and consequence values are calculated and reported on an absolute basis, then they may be reported graphically in combination with one another (Chapter 3), or simply as the product of frequency and consequence. Table 5 contains some examples of typical risk estimates (frequency and consequence products). Based on absolute risk estimates, you can decide whether the risk of a specific activity exceeds your threshold of risk tolerance (risk goal). If so, analysts can estimate the reduction in risk, given that certain improvements are made, assumptions changed, or operating circumstances eliminated. 

Quantum yield and luciferase activity The quantum yield of coelenterazine in the luminescence reaction catalyzed by Oplophorus luciferase was 0.34 when measured in 15 mM Tris-HCl buffer, pH 8.3, containing 0.05 M NaCl at 22°C (Shimomura et al., 1978). The specific activity of pure luciferase in the presence of a large excess of coelenterazine (0.9pg/ml) in the same buffer at 23°C was 1.75 x 1015 photons s 1 mg-1 (Shimomura et al., 1978). Based on these data and the molecular weight of luciferase (106,000), the turnover number of luciferase is calculated at 55/min. 

Michaelis constant K for D-glyca] hydration. Approximate value calculated from specific activity with M, 50,000. 

Specific activity was calculated by the rate of ILl-PS divided by that of PS-C. 

With respect to CO oxidation an activity order similar to that described above for CH4 combustion has been obtained. A specific activity enhancement is observed for Lai Co 1-973 that has provided a 10% conversion of CO already at 393 K, 60 K below the temperature required by LalMnl-973. This behavior is in line with literature reports on CO oxidation over lanthanum metallates with perovskite structures [17] indicating LaCoOs as the most active system. As in the case of CH4 combustion, calcination at 1373 K of LalMnl has resulted in a significant decrease of the catalytic activity. Indeed the activity of LalMnl-1373 is similar to those of Mn-substituted hexaaluminates calcined at 1573 K. Dififerently from the results of CH4 combustion tests no stability problems have been evidenced under reaction conditions for LalMnl-1373 possibly due to the low temperature range of CO oxidation experiments. Similar apparent activation energies have been calculated for all the investigated systems, ranging from 13 to 15 Kcal/mole, i.e almost 10 Kcal/mole lower than those calculated for CH4 oxidation. 

Figure 9.21 Specific activity and Pd-Pd bond distance calculated from XRD data against the concentration of Fe in Pd-Fe/C elecfrocatalysts treated at 500 °C. (Reproduced with permission from Shao et al. [2006c].)...

To minimize experiment time, the highest possible source activity is desirable, with the constraint that the source line width should not increase sigiuficantly (maximum by a factor of 2-3) over the 9-12 months duration of the mission. Calculations and tests indicate an optimum specific activity for Co at 1 Ci per cm [42, 43], Sources of 350 mCi Co/Rh with a specific activity close to this value and extremely narrow source fine width (<0.13 mm s at room temperature), given... 

Measurement of specific activity. The half-life of a nuclide can be readily calculated if both the number of atoms and their rate of decay can be measured, i.e., if the activity A and the number of atoms of P can be measured, then X is known from A = XP. As instrumentation for both atom counting and decay counting has improved in recent decades, this approach has become the dominant method of assessing half-lives. Potential problems with this technique include the accurate and precise calibration of decay-counter efficiency and ensuring sufficient purity of the nuclide of interest. This technique provides the presently used half-lives for many nuclides, including those for the parents of the three decay chains, U, U (Jaffey et al. 1971), and Th. 

Calorimetry. Radioactive decay produces heat and the rate of heat production can be used to calculate half-life. If the heat production from a known quantity of a pure parent, P, is measured by calorimetry, and the energy released by each decay is also known, the half-life can be calculated in a manner similar to that of the specific activity approach. Calorimetry has been widely used to assess half-lives and works particularly well for pure a-emitters (Attree et al. 1962). As with the specific activity approach, calibration of the measurement technique and purity of the nuclide are the two biggest problems to overcome. Calorimetry provides the best estimates of the half lives of several U-series nuclides including Pa, Ra, Ac, and °Po (Holden 1990). 

The specific activity is a measure of activity, and is fined as the activity per unit mass or per unit volume. This activity is usually expressed in curies per gram and may be calculated by... 

To determine the efficiency of aminoacylation of [14C]Phe-tRNA, 5 fil aliquots of the aminoacylation mixture are withdrawn before and after the reaction the samples taken from the reaction mixture at the end of the incubation are spotted onto 3-MM paper discs (Schleicher Schuell) and processed by the cold TCA precipitation method, while the sample taken before the reaction is spotted on a paper disc pretreated empty by the same cold TCA procedure. Determination of the radioactivity present on these filters by liquid scintillation counting allows one to calculate the aminoacylation efficiency of the reaction (which, for phenylalanine, should be >2% of total tRNA). The specific activity of the [14C] Phe-tRNA can be determined after one-step purification of Phe-tRNA by BD cellulose chromatography (Gillam et al., 1968), followed by determination of the radioactivity and of the A260. 

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