Water calorimetry: a correction to the heat defect calculations.In a recent publication, we used a reaction. model (model III) to calculate the heat defect defect - bug for the irradiation irradiation /ir·ra·di·a·tion/ (i-ra?de-a´shun) 1. radiotherapy. 2. the dispersion of nervous impulse beyond the normal path of conduction. 3. of aqueous aqueous /aque·ous/ (a´kwe-us) 1. watery; prepared with water. 2. see under humor. a·que·ous adj. solutions with ionizing radiation i·on·i·zing radiation n. High-energy radiation capable of producing ionization in substances through which it passes. Ionizing radiation at 21 [degrees]C. Subsequent work has revealed that the literature value used for one of the rate constants in the model was incorrect. A revised model (model IIIR IIIR Independent International Investment Research (UK) IIIR Integration of Internet Information Resources ) incorporates the correct rate constant for 21 [degrees]C. Versions of models III and IIIR were created for irradiations at 4 [degrees]C. For our current water calorimetry calorimetry (kăl'ərĭm`ətrē), measurement of heat and the determination of heat capacity protocol, the values of the heat defect for [H.sub.2]/[O.sub.2]-water (water saturated saturated /sat·u·rat·ed/ (sach´ah-rat?ed) 1. denoting a chemical compound that has only single bonds and no double or triple bonds between atoms. 2. unable to hold in solution any more of a given substance. with a flow of 43 % [H.sub.2] and 57 % [O.sub.2], by volume) at 21 [degrees]C predicted by model III and model IIIR are similar but the value for 4 [degrees]C predicted by III is 30 % smaller than the value predicted by IIIR. Model IIIR predicts that the values of the heat defect at 21 [degrees]C and 4 [degrees]C lie within the range -0.023[+ or -]0.002, in agreement with the values obtained from our water calorimetry measurements done usin g pure water and [H.sub.2]-saturated water at 21 [degrees]C and 4 [degrees]C. The yields of hydrogen peroxide hydrogen peroxide, chemical compound, H2O2, a colorless, syrupy liquid that is a strong oxidizing agent and, in water solution, a weak acid. It is miscible with cold water and is soluble in alcohol and ether. in [H.sub.2]/[O.sub.2]-water at 21 [degrees]C and 4 [degrees]C were measured and agree with the predictions of model IIIR. Our water calorimetry measurements made with pure water and [H.sub.2]-saturated water are now of sufficient quality that they can be used to determine the heat defect for [H.sub.2]/[O.sub.2]-water better than can be done by simulations. However, consistency between the three systems continues to be an excellent check on water purity Purity: see Pearl, The. Purity See also Modesty. almond symbol of the Virgin Mary’s innocence. [O.T.: Numbers 17: 1–11; Art: Hall, 14] crystal its transparency symbolizes pureness. which is crucial, especially for the pure water system. Key words: dose rate; heat defect; radiation chemistry; water calorimetry. 1. Introduction Using a water calorimeter calorimeter: see calorimetry. calorimeter Device for measuring heat produced during a mechanical, electrical, or chemical reaction and for calculating the heat capacity of materials. , the absorbed dose ab·sorbed dose n. The quantity of radiation energy, expressed in rads, that is administered or absorbed per unit mass of target. absorbed dose to water from low LET (linear energy transfer) ionizing radiation such as high energy x rays and by [gamma] rays is obtained by measuring the temperature rise produced in the water by the absorbed dose and correcting for the effect of other materials (walls, etc.) on the temperature rise. This corrected temperature rise may be greater or lower than that which corresponds exactly to the absorbed dose because the chemical changes in the irradiated solution may be exothermic exothermic /exo·ther·mic/ (-ther´mik) marked or accompanied by evolution of heat; liberating heat or energy. ex·o·ther·mic or ex·o·ther·mal adj. 1. or endothermic endothermic /en·do·ther·mic/ (-ther´mik) characterized by or accompanied by the absorption of heat. en·do·ther·mic or en·do·ther·mal adj. 1. and must be accounted for by a correction factor called the heat defect ([K.sub.HD]), [K.sub.HD] = ([E.sub.a] - [E.sub.h])/[E.sub.a], where [E.sub.a] is the energy absorbed by the water and [E.sub.h] is the energy which appears as heat. If pure water (water saturated with nitrogen or argon argon (är`gŏn) [Gr.,=inert], gaseous chemical element; symbol Ar; at. no. 18; at. wt. 39.948; m.p. −189.2°C;; b.p. −185.7°C;; density 1.784 grams per liter at STP; valence 0. ), or [H.sub.2]-water (water saturated with [H.sub.2]), is used in the calorimeter, the temperature rise, after a small priming dose, will correspond exactly to the energy deposited by the absorbed dose and the heat defect will equal zero [1]. However, small amounts of oxygen or organic impurities can result in a significant heat defect. [H.sub.2]-water is less sensitive than pure water to most organic impurities. [H.sub.2]/[O.sub.2]-water (water saturated with a gas mixture of 43 % [H.sub.2] and 57 % [O.sub.2], by volume) is quite insensitive in·sen·si·tive adj. 1. Not physically sensitive; numb. 2. a. Lacking in sensitivity to the feelings or circumstances of others; unfeeling. b. to organic impurities but [H.sub.2]/[O.sub.2]-water has a significant heat defect of about-0.[O.sub.2] which must be calculated but which is fairly constant for the first few hundred Gy and is insensitive to small changes in the ratio of [H.sub.2] to [O.sub.2] in the gas stream used to saturate sat·u·rate v. Abbr. sat. 1. To imbue or impregnate thoroughly. 2. To soak, fill, or load to capacity. 3. To cause a substance to unite with the greatest possible amount of another substance. the water. In our previous publication, heat defects were calculated by a computer simulation which used model III to describe the radiation chemistry [1]. If simulations predict a heat defect for [H.sub.2]/[O.sub.2]-water relative to the predictions for pure water and [H.sub.2]-water, which agree with the calorimetric cal·o·rim·e·ter n. 1. An apparatus for measuring the heat generated by a chemical reaction, change of state, or formation of a solution. 2. measurements, we can assume with reasonable certainty that (a) there were no significant impurities in the pure water or the [H.sub.2]-water and (b) the heat defect was calculated correctly for the [H.sub.2]/[O.sub.2]-water. Since the publication of model III for 21 [degrees]C, a version of model III was created which conforms to the radiation chemistry at 4 [degrees]C, at which temperature it predicts heat defects of -0.016 for [H.sub.2]/[O.sub.2]-water and zero for pure water and [H.sub.2]-water. This is contrary to our water calorimetry measurements at 4 [degrees]C which indicate that [H.sub.2]/[O.sub.2]-water has a heat defect of -0.023. if a value of zero is assumed for pure water and [H.sub.2]-wate r. This disagreement led to finding an incorrect rate constant in the literature used to create model III. The correct rate constant is given here and the revised version Revised Version n. A British and American revision of the King James Version of the Bible, completed in 1885. Revised Version Noun of model III is called model IIIR. Although the error caused by using model HI at 21 [degrees]C was minor, it is possible that model III could lead to significant errors at any temperature, depending on the irradiation protocol. The predictions of the previous publication [1] were recalculated using model IIIR and compared to calculations using model III and an earlier model, model II [2]. Many water calorimeters are operated at 4 [degrees]C. The 4 [degrees]C version of model IIIR is presented. The yields of [H.sub.2][O.sub.2] in [H.sub.2]/[O.sub.2]-water were measured at both 4 [degrees]C and 21 [degrees]C and compared to the predictions of model IIIR. Different software is now being used to do the simulations. Results using the present and previous software are presented. 2. Experimental The materials and experimental procedures have been described [1]. The water used in this study was purified by passage through a Millipore RO10 reverse osmosis reverse osmosis n. The movement of a solvent in the opposite direction from osmosis in such a manner that the solvent moves from a solution of greater concentration through a membrane to a solution of lesser concentration. unit followed by a Millipore Milli-Q UY system. (1) Ultrapure grade [N.sub.2], [O.sub.2], and [H.sub.2] were used for bubbling See DOM. the solutions. Gas flowrates were measured using a Matheson model 8141 mass flowmeter See flow meter. . Water, saturated with [N.sub.2] to remove air, is referred to as "pure water" because the dissolved dis·solve v. dis·solved, dis·solv·ing, dis·solves v.tr. 1. To cause to pass into solution: dissolve salt in water. 2. [N.sub.2] plays no significant role in the radiolysis ra·di·ol·y·sis n. pl ra·di·ol·y·ses Molecular decomposition of a substance as a result of radiation. ra . In order to measure the [H.sub.2][O.sub.2] (hydrogen peroxide) produced when [H.sub.2]/[O.sub.2] water was irradiated, 6.0 mL of the solution was irradiated in a Pyrex irradiation tube of 20 mm o.d. A silicone rubber Noun 1. silicone rubber - made from silicone elastomers; retains flexibility resilience and tensile strength over a wide temperature range synthetic rubber, rubber - any of various synthetic elastic materials whose properties resemble natural rubber seal at the top of the tube formed a leak-proof seal through which were inserted two concentric Coming from the center, or circles within circles. For example, tracks on a hard disk are concentric. Tracks on optical media are concentric or spiral shaped (in a coil) depending on the type. Pyrex tubes, sealed together, and constructed in such a way so as to permit gas to be bubbled through the 6.0 mL of water and then to exit the vessel. The solution was bubbled for 25 mm to ensure saturation saturation, of an organic compound saturation, of an organic compound, condition occurring when its molecules contain no double or triple bonds and thus cannot undergo addition reactions. and then the tube assembly was raised above the water level without stopping the gas flow or causing any leak (programming) leak - With a qualifier, one of a class of resource-management bugs that occur when resources are not freed properly after operations on them are finished, so they effectively disappear (leak out). This leads to eventual exhaustion as new allocation requests come in. at the silicone silicone, polymer in which atoms of silicon and oxygen alternate in a chain; various organic radicals, such as the methyl group, CH3, are bound to the silicon atoms. seal. A valve between the mass flowmeter and the irradiation vessel was then partially opened to allow some of the gas to escape before reaching the vessel, thereby reducing the flow of gas across the surface of the water (to reduce evaporation evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at a rate that depends on the amount of surface exposed, the humidity ) without changing the relative flowrates. This flow was maintained until the end of the irradiation. The irradiation tube was reprod ucibly positioned inside a Lucite tube of 37 mm o.d. and 30 mm i.d. through which water was pumped by a Neslab model RTE- 111 constant temperature circulating cir·cu·late v. cir·cu·lat·ed, cir·cu·lat·ing, cir·cu·lates v.intr. 1. To move in or flow through a circle or circuit: blood circulating through the body. 2. water bath (Neslab Instruments Inc., Portsmouth, NH, USA) to control the temperature of the irradiated solution to [+ or -]0.05 [degrees]C. The solutions were irradiated with [Co.sup.60] [gamma] rays from an Eldorado 6 therapy unit (Atomic Energy atomic energy: see nuclear energy. of Canada) at a dose rate of about 2.2 Gy [min.sup.-1] Calibration calibration /cal·i·bra·tion/ (kal?i-bra´shun) determination of the accuracy of an instrument, usually by measurement of its variation from a standard, to ascertain necessary correction factors. of the dose rate was done by irradiating Fricke dosimeter do·sim·e·ter n. An instrument that measures the amount of radiation absorbed in a given period. dosimeter an instrument used to detect and measure exposure to radiation. solutions [1, 3] in the same setup See BIOS setup and install program. . Measurement of the [H.sub.2][O.sub.2] was done using the potassium iodide potassium iodide n. A white crystalline compound used as a source of iodine to treat thyrotoxic crisis and to prevent thyroid cancer in the event of overexposure to nuclear radiation. It is also used as an expectorant and antifungal. method [4]. 3. Results We have published two reaction models for calculating the heat defect for aqueous solutions used in water calorimeters. Model II was published in 1991 (2) and an "improved" model, model III, in 1997 (1). All computer simulations followed the measurement protocol in use at the time, i.e., the same dose rate, irradiation duration and interval between irradiations. The current protocol is a set of 10 irradiation periods, of 120 s each, at a dose rate of 1.54 Gy [min.sup.-1], each irradiation period after the first one beginning 600 s after the start of the previous one. For both measurements and simulations, the linear regressions Linear regression A statistical technique for fitting a straight line to a set of data points. of the temperature readings from 120 s to 20 s before the start of each irradiation, and from 20 s to 120 s after the end of each irradiation, were extrapolated to the time of mid-irradiation. In the measurements, the difference between the extrapolated values at mid-irradiation represents the temperature rise caused by the absorbed dose as well as the effect of the heat defect (5). T he simulations predict the chemical changes throughout the run and the temperature changes due to these chemical changes are calculated and extrapolated to mid-irradiation. The simulations include slow chemical changes, initiated by previous irradiations, but which are still occurring during later irradiations. We now use FACSIMILE facsimile (făksĭm`əlē) or fax, in communications, system for transmitting pictures or other graphic matter by wire or radio. version H012 (AEA Technology AEA Technology plc was formed in 1996 as the privatised offshoot of the United Kingdom Atomic Energy Authority. Originally it consisted of divisions with expertise in a wide variety of areas, mostly the products of nuclear-related research. , U.K.) to run the simulations. Previously, we used MACKSIM (Atomic Energy of Canada). MACKSIM computes the chemical changes due to radiolysis and we used these changes to manually calculate the heat defect. The MACKSIM output contains the rounded-off values of the simulation and, if the change in the concentration of a species was small compared to its initial concentration, approximations had to be made to the output values in order to calculate the heat defect. FACSIMILE computes both the heat defect and the chemical changes using its full precision. The heat defects calculated by FACSIMILE and MACKSIM for common irradiation conditions at 4 [degrees]C and 21 [degrees]C never differed by more than 0.2 %. Recently, the decision was made to operate the NRC NRC abbr. 1. National Research Council 2. Nuclear Regulatory Commission Noun 1. NRC - an independent federal agency created in 1974 to license and regulate nuclear power plants "sealed" water calorimeter at 4 [degrees]C in order to avoid the convective heat transfer Convective heat transfer is a mechanism of heat transfer occurring because of bulk motion (observable movement) of fluids. This can be contrasted with conductive heat transfer, which is the transfer of energy molecule by molecule through a solid or fluid, and radiative heat that occurs at 21 [degrees]C (6). The heat defect had to be calculated for [H.sub.2]/[O.sub.2]-water irradiated at 4 [degrees]C. To do this, model III was adjusted to conform to Verb 1. conform to - satisfy a condition or restriction; "Does this paper meet the requirements for the degree?" fit, meet coordinate - be co-ordinated; "These activities coordinate well" 4 [degrees]C using the temperature dependencies of the G-values (2) and rate constants given by Elliot (7). The concentration of [O.sub.2] in water saturated at 101.325 kPa is 1.40x[10.sup.-3] mol [L.sup.-1] at 21 [degrees]C and 1.90x[10.sup.-3] mol [L.sup.-1] at 4 [degrees]C (8). The concentration of [H.sub.2] in water saturated at 101.325 kPa is 8.50x[10.sup.-4] mol [L.sup.-1] at 21 [degrees]C and 9.30x[10.sup.-4] mol [L.sup.-1] at 4 [degrees]C (9). The pH of pure water is 7.07 at 21 [degrees]C and 7.39 at 4 [degrees]C (10). The density of water was taken as 0.998 g [cm.sup.-3] at 21 [degrees]C and 1.000 at 4 [degrees]C (11). Account was taken of the fact that the calorimeter was saturated wit h gases at room temperature and cooled to 4 [degrees]C after sealing off the calorimeter. Simulations using model III, done for our current irradiation protocol, predicted a heat defect for [H.sub.2]/[O.sub.2]-water of -0.023 at 21 [degrees]C and -0.016 at 4 [degrees]C. However, the water calorimetry of pure water and [H.sub.2]-water, assuming a zero heat defect, consistently indicated that the heat defect for [H.sub.2]/[O.sub.2]-water should be -0.023 at both 21 [degrees]C and 4 [degrees]C (12). The fact that the experimental results were unchanged for many refills of pure water and [H.sub.2]-water was a strong indication that the solutions were adequately pure. This led us to conclude that the heat defect predicted for [H.sub.2]/[O.sub.2]-water at 4 [degrees]C using model III was incorrect. Extensive testing revealed that the problem stemmed stemmed adj. 1. Having the stems removed. 2. Provided with a stem or a specific type of stem. Often used in combination: stemmed goblets; long-stemmed roses. from the rate constants in the equilibrium equilibrium, state of balance. When a body or a system is in equilibrium, there is no net tendency to change. In mechanics, equilibrium has to do with the forces acting on a body. defined by reactions 37 and 38 of model III (1). To avoid confusion, we shall retain the same reaction numbers as in our earl ier publication (1). [HO.sub.2] + [OH.sup.-] [right arrow] [O.sup.-.sub.2] + [H.sub.2]O (37) [O.sup.-.sub.2] + [H.sub.2]O [right arrow] [HO.sub.2] + [OH.sup.-] (38) The rate constants for these reactions in pure water have not been measured. Elliot (7) concluded that [k.sub.37], the rate constant for reaction (37), was likely to be similar to [k.sub.33]. OH + [OH.sup.-] [right arrow] [O.sup.-] + [H.sub.2]O (33) Taking [k.sub.37] = [k.sub.33], Elliot evaluated [k.sub.38] using the established values of equilibrium constants Noun 1. equilibrium constant - (chemistry) the ratio of concentrations when equilibrium is reached in a reversible reaction (when the rate of the forward reaction equals the rate of the reverse reaction) (7). Due to the inadvertent replacement of the value of one equilibrium constant with that of another, Elliot calculated [k.sub.38] = 1.36X[10.sup.6] L [mol.sup.-1] [s.sup.-1] at 21 [degrees]C. The correct calculation yields [k.sub.38] = 1.44X[10.sup.-1] L [mol.sup.-1] [s.sup.-1] at 21 [degrees]C and 1.94X[10.sup.-2] L [mol.sup.-1] [s.sup.-1] at 4 [degrees]C. Although never measured in water, the rate constant [k.sub.38] has been measured in dimethyl di·meth·yl n. An organic compound, especially ethane, containing two methyl groups. formamide and in acetonitrile acetonitrile /ac·e·to·ni·trile/ (as?e-to-ni´tril) a colorless liquid with an etherlike odor used as an extractant, solvent, and intermediate; ingestion or inhalation yields cyanide as a metabolic product. for solutions which contained up to 0.6 mol [L.sup.-1] [H.sub.2]O (13,14). The values reported for [k.sub.38] in these solvents ranged from 0.5X[10.sup.-3] L [mol.sup.-1] [s.sup.-1] to 3.5X[10.sup.-3] L [mol.sup.-1] [s.sup.-1] with an indication in one report (14) that the value might increase with increase in water concentration. The corrected values of [k.sub.37] and [k.sub.38] ensure that, in neutral solutions, the equ ilibrium is greatly in favor of upon the side of; favorable to; for the advantage of. See also: favor reaction (37) with the result that there is no rapid conversion of [O.sup.-.sub.2] into [HO.sub.2] during the irradiation. For this reason, the difference between the values we now accept for [k.sub.38] and the smaller, published values for dimethyl formamide and acetonitrile solutions containing some water, does not affect the predicted heat defects. We created model IIIR for 21 [degrees]C which is identical to model III (1) except that it contains the recalculated value of [k.sub.38]. In view of the fact that water calorimetry is often carried out at 4 [degrees]C, it is essential to have a 4 [degrees]C version of Model IIIR. This was created using Elliot's values for the temperature dependencies of the rate constants and G-values (7). The reactions and rate constants for the 4 [degrees]C version of IIIR are given in Table 2. and the G-values are given in Table 2. The enthalpies of formation were published earlier (2). For [H.sub.2]/[O.sub.2]-water, the concentration of [O.sub.2] was taken to be 8.1X[10.sup.-4] mol [L.sup.-1] at 21 [degrees]C and 8.2X[10.sup.-4] mol [L.sup.-1] at 4 [degrees]C and the concentration of [H.sub.2] was taken to be 3.5X[10.sup.-4] mol [L.sup.-1] at 21 [degrees]C and 3.4X[10.sup.-4] mol [L.sup.-1] at 4 [degrees]C. These concentrations are a function of several factors, the gas space volume at both temperatures, the water volume at both temperatures, the solubility solubility Degree to which a substance dissolves in a solvent to make a solution (usually expressed as grams of solute per litre of solvent). Solubility of one fluid (liquid or gas) in another may be complete (totally miscible; e.g. of the gases at both temperatures and the fact that the water was close to room temperature when it was saturated with gas. Figure 1 shows the heat defects for [H.sub.2]/[O.sub.2]-water versus time, at 4[degrees]C and 21 [degrees]C, predicted by model IIIR for 2 different dose rates, 1.54 Gy [min.sup.-1] and 4.62 Gy [min.sup.-1]. For our current irradiation protocol, the predicted heat defects are similar whether reactions (37) and (38) are included or not, which is why simulations using model II [2] did not show the same inconsistency in·con·sis·ten·cy n. pl. in·con·sis·ten·cies 1. The state or quality of being inconsistent. 2. Something inconsistent: many inconsistencies in your proposal. at 4[degrees]C as experienced with model III. Both model III and model IIIR predict close to the same values for the chemical changes at long times after the irradiation. The error in model III results in a greater slope for the linear regression used to extrapolate extrapolate - extrapolation to mid-irradiation. This can be seen by comparing Fig. 1 in the previous publication [1] to Fig. 1 in the present paper. Figure 1 shows that a plot of the heat defect versus time is almost identical for the 1st and the 10th irradiations of a set. The value of the heat defect, extrapolated to mid-irradiation in the same manner as the calorimetry protocol, is the value which is applied to the experimental results. The extrapolated value of the 1st run of each set is indicated to the left of the data points in Fig. 1. It can be seen that the heat defect does depend significantly on the dose rate. For our current protocol, the heat defect is predicted to be -0.0252 at 21[degrees]C and -0.0212 at 4 [degrees]C. Careful measurements could probably determine if this predicted difference is real, i.e., whether the conversion of model IIIR from 21 [degrees]C to 4[degrees]C is reliable. The relationship between the G-values in the model and the predicted heat defect is complicated by the fact that [H.sub.2][O.sub.2] is produced from three different molecules [H.sub.2]O, [H.sub.2], and [O.sub.2], by processes, some of which are exothermic and some of which are endothermic. In order to get some idea of the dependence of the heat defect on the G-values chosen for the model, we calculated the heat defect using model IIIR for 4 [degrees]C using both the G- values in Table 2 and the G- values assigned as·sign tr.v. as·signed, as·sign·ing, as·signs 1. To set apart for a particular purpose; designate: assigned a day for the inspection. 2. to 21 [degrees]C [1]. The heat defect predicted for 4 [degrees]C using the G-values in Table 2 was--0.021 (see Fig. 1) compared to a value of--0.023 when the G- values for 21 [degrees]C were used. We may ask whether the G- values, and their temperature dependencies are sufficiently well known that the difference predicted between the heat defect at 4 [degrees]C and at 21 [degrees]C is meaningful. The G- values for model IIIR at 4 [degrees]C are about 2 % different than the values at 21 [degrees]C. Careful measurements of G- values have uncertainties of 2 % to 3 % [15]. However, the conditions under which the G- value of one species is measured are not the same as the conditions for the measurement of the G-value of another species. Because of this, Elliot [7] found the measured value of G([H.sub.2][O.sub.2]) to be 6 % greater than the value that gave a material balance. The material balance which is required is that the total number of hydrogen atoms and oxygen atoms in the system must not change. We were able to achieve a predicted heat defect of -0.023 at both 21 [degrees]C and 4 [degrees]C by changing the individual G- values at both temperatures in an arbitrary way, while maintaining a material ba lance, and ensuring that none of the G- values was changed by more than 4 %. However, when they are created in this way, there is no logical connection between the set of G- values at 4 degrees]C and the set at 21 [degrees]C, so this method cannot be recommended. Neither were we able to find any particular rate constants in model IIIR that could account for the difference between the predicted heat defects at 4 [degrees]C and 21 [degrees]C. The difference in the predicted heat defects as the rate constants and G- values were varied between the values assigned to 4 [degrees]C and 21 [degrees]C was taken to be a measure of the uncertainty in the predicted heat defects. We conclude that the precision of the G- values and rate constants in model IIIR is insufficient to reduce the uncertainty in our calculated heat defects for [H.sub.2]/[O.sub.2]-water at 4 [degrees]C or 21 [degrees]C to less than [+ or -]0.003. All uncertainties are quoted as 1 [sigma]. Once pure water and [H.sub.2]-water have been given a suffic iently large dose to reach a steady state of chemical composition, the prediction that they have a heat defect within n0.001 of zero is independent of the model used. Consequently, the uncertainty of the predicted heat defect would be about 0.001 for pure water and [H.sub.2]-water if the water in the calorimeter were as pure as the water in the model. Pure water and H2-water are more susceptible to trace impurities than is [H.sub.2]/[O.sub.2]-water. We believe that we can now determine the heat defect for [H.sub.2]/[O.sub.2]-water more reliably by basing it on the water calorimetry of pure water and [H.sub.2]-water than by basing it on model simulations as long as the calorimetry results for these three systems are consistent with one another over several fills of the calorimeter. The radiolysis of [H.sub.2]/[O.sub.2]-water produces [H.sub.2][O.sub.2] whose concentration can be measured with high accuracy and precision [4]. We measured the yields of [H.sub.2][O.sub.2] in [H.sub.2]/[O.sub.2]-water at 4 [degrees]C and 21 [degrees]C. In these measurements, unlike the calorimetry measurements, the irradiated water was saturated at the temperature of the irradiation, hence, the concentrations of [H.sub.2] and [O.sub.2] were slightly different in the two cases. Simulations were carried out mimicking the conditions of the irradiations. Ten measurements each were made at 4 [degrees]C and 21 [degrees]C using dose rates of 2.22 Gy [min.sup.-1] and irradiation times of 15 min, 30 min, and 60 min. The measured yields of [H.sub.2][O.sub.2] and the yields predicted by simulation are given in Table 3. The average ratio of the simulated [H.sub.2][O.sub.2] yields to the measured yields was 1.028[+ or -]0.010 at 21 [degrees]C and 0.983[+ or -]0.008 at 4 [degrees]C. When we retained the 4 [degrees]C rat e constants but replaced the G- values in the 4 [degrees]C simulation with the G-values for 21 [degrees]C, the average ratio changed from 0.983[+ or -]0.008 to 1.004[+ or -]0.008. The latter values are shown in parentheses See parenthesis. parentheses - See left parenthesis, right parenthesis. in Table 3. This suggests that the G- values chosen for 4 [degrees]C and 21 [degrees]C differ more than they ought to. Figure 5 of our earlier publication (1) compared the simulation (model III) against the measurements of the [H.sub.2][O.sub.2] concentration versus dose for the irradiation of water that was saturated with [H.sub.2] except that it contained 6X[10.sup.-7] M [O.sub.2]. The use of model IIIR caused no significant change to this figure. The irradiation of water containing [H.sub.2] and a little [O.sub.2] results in the production of [H.sub.2][O.sub.2] until the [O.sub.2] is depleted de·plete tr.v. de·plet·ed, de·plet·ing, de·pletes To decrease the fullness of; use up or empty out. [Latin d . At that point, a chain reaction reduces the concentration of [H.sub.2][O.sub.2] to a low level (16), a process that produces heat. The dose at which the concentration of [H.sub.2][O.sub.2] decreases most rapidly produces heat the most rapidly and also corresponds to a minimum in the differential heat defect. Krauss and Roos (17) have reported both the simulation and measurement of the heat defect for the irradiation of water containing 7.6X[10.sup.-5] mol[L.sup.-1] [O.sup.2] and 8.0X[10.sup.-4] mol[L.sup.-1] [H.sub.2] at 20 [degrees]C. Our simulation using model IIIR is in good agreement with their results. However, a simulation of the same aqueous system at 4 [degrees]C, indicated that the minimum differential heat defect would occur at a 5.9 % higher dose at 4 [degrees]C than at 21 [degrees]C. If the radiolysis were simulated perfectly and the time at which t he minimum differential heat defect occurred were measured, one might imagine using these values to calculate the dose rate. Several obstacles stand in the way of doing this with a precision of better than a few percent. If the dose rate is not identical throughout the vessel, the concentrations of [H.sub.2][O.sub.2] and [O.sub.2] will change at different rates throughout the vessel and [H.sub.2][O.sub.2] and [O.sub.2] will diffuse diffuse /dif·fuse/ 1. (di-fus´) not definitely limited or localized. 2. (di-fuz´) to pass through or to spread widely through a tissue or substance. dif·fuse adj. from regions of higher concentration to regions of lower concentration. This explanation was used by Krauss and Roos to explain a second "exothermal exothermal /exo·ther·mal/ (ek?so-ther´mal) exothermic. exothermal, exothermic marked or accompanied by the evolution of heat; liberating heat or energy. peak" which occurred when the irradiation was stopped after the first minimum and restarted 16 h later. Oxygen can also enter the water from the small gas bubble A bit in bubble memory or a symbol in a bubble chart. in the vessel and change the concentration of dissolved [O.sub.2]. The possibility exists that diffusion diffusion, in chemistry, the spontaneous migration of substances from regions where their concentration is high to regions where their concentration is low. Diffusion is important in many life processes. of [O.sub.2] from the air through the seals can occur. The permeability permeability /per·me·a·bil·i·ty/ (per?me-ah-bil´i-te) the property or state of being permeable. per·me·a·bil·i·ty n. 1. The property or condition of being permeable. 2. of polyethylene polyethylene (pŏl'ēĕth`əlēn), widely used plastic. It is a polymer of ethylene, CH2=CH2, having the formula (-CH2-CH2-)n to [O.sub.2] is known (18). The presence in the system of plastic which has been exp exp abbr. 1. exponent 2. exponential osed to significant oxygen concentrations before the irradiation means that oxygen dissolved in the plastic will diffuse into the system. Krauss and Roos concluded that the effects of diffusion were negligible  This article or section is written like a personal reflection or and may require .Please [ improve this article] by rewriting this article or section in an . for the irradiation protocol they used. Two other problems remain. The precision of the simulation will limit the precision with which the dose rate can be measured in this way and, as shown in Table 3, our model predictions for [H.sub.2][O.sub.2] production in [H.sub.2]/[O.sub.2]-water at 21 [degrees]C and 4 [degrees]C differ from our measurements by about +3 % and -2 %, respectively. The other problem concerns the fact that the precision with which the [O.sub.2] concentration can be measured is usually several percent. A study of the oxygen meter used by Krauss and Roos has been reported (19). An error of 2.4 % in the measured [O.sub.2] concentration was found for an [O.sub.2] concentration of about 2.5X[10.sup.-4] mol [L.sup.-1] when the CellOx 325 was calibrated cal·i·brate tr.v. cal·i·brat·ed, cal·i·brat·ing, cal·i·brates 1. To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument): in accord with the manufacturer's ins tructions. Careful temperature control and equilibration equilibration /equi·li·bra·tion/ (e-kwil?i-bra´shun) the achievement of a balance between opposing elements or forces. occlusal equilibration was required to reduce the error to less than 1 %. The difficulties increase as the [O.sub.2] concentration goes down because the sensor A device that measures or detects a real-world condition, such as motion, heat or light and converts the condition into an analog or digital representation. An optical sensor detects the intensity or brightness of light, or the intensity of red, green and blue for color systems. reading at zero oxygen concentration must be subtracted from all readings. Table 4 of our previous publication (1) listed the accumulated ac·cu·mu·late v. ac·cu·mu·lat·ed, ac·cu·mu·lat·ing, ac·cu·mu·lates v.tr. To gather or pile up; amass. See Synonyms at gather. v.intr. To mount up; increase. pre-doses required to bring the heat defect to within [+ or -]0.001 of unity for pure water and water containing traces of [O.sub.2]. These simulations were repeated using model IIIR and the results for 21 [degrees]C and 4 [degrees]C are given in Table 4 for dose rates of 1 Gy [min.sub.-1] and 20 Gy [min.sub.-1]. It should be noted that these pre-doses do not remove the 02. Rather, the pre-dose establishes steady state concentrations of the species present and, in fact, the concentration of [O.sub.2] is higher at the end of a pre-dose than it is initially. 4. Conclusions The earliest measurements of water calorimetry (20) encountered problems of water purity. When [H.sub.2]/[O.sub.2] water was shown to be insensitive to impurities, it was used as a standard system for which the heat defect was calculated using simulations (21). If we accept a heat defect of zero for our pure water and [H.sub.2]-water, our experimental calorimetry forces us to accept a heat defect of -0.023 for [H.sub.2]/[O.sub.2]-water at both 21 [degrees]C and 4 [degrees]C. Simulations show that there are no simple changes to the C-values and rate constants which can reconcile this value of -0.023 with the values of -0.025 and -0.021 predicted for 21 [degrees]C and 4 [degrees]C, respectively, at 1.54 Gy [min.sub.-1] by model IIIR. Previously, we placed a value of [+ or -] 0.005 on the uncertainty in the predicted heat defect for [H.sub.2]/[O.sub.2]-water (2). We have attempted, over the years, to improve the model and an uncertainty of [+ or -]0.003 on a predicted heat defect of about -0.023 now seems reason able. Recently, it became clear that our water purity is sufficiently good that water calorimetry with pure water and [H.sub.2]-water consistently measure the same dose rate and that their response is stable, for many refills, when compared to [H.sub.2]/[O.sub.2]-water. This suggests that the uncertainty in the simulation of the heat defect of [H.sub.2]/[O.sub.2]-water need not be taken as the major source of uncertainty in the calculated dose rate. We conclude that water calorimetry using pure water and H2-water can now provide us with a better measure of the heat defect of [H.sub.2]/[O.sub.2]-water than do our simulations. We assign a value of zero to the heat defect of pure water and [H.sub.2]-water when the water meets our criteria for purity. In this regard, [H.sub.2]/[O.sub.2]-water still plays an important role as a test of the purity of the water. If [H.sub.2]/[O.sub.2]-water continues to be used in this role, simulations of [H.sub.2]/[O.sub.2]-water will still be required because the heat defect of [H.sub.2]/[O.sub.2]-water is sufficiently sensitive to the dose rate that one must carry out simulations for the operational dose rate. [FIGURE 1 OMITTED]
Table 1
Model IIIR: reactions and rate constants (4 [degrees]C)
Reactions (a)
1 [e.sup.-.sub.aq] + [right arrow] [H.sub.2] +
[e.sup.-.sub.aq] [OH.sup.-]
+ [OH.sup.-]
2 [e.sup.-.sub.aq] + H [right arrow] [H.sub.2] +
[OH.sup.-]
3 [e.sup.-.sub.aq] + OH [right arrow] [OH.sup.-]
4 [e.sup.-.sub.aq] + [right arrow] [OH.sup.-] + OH
[H.sub.2][O.sub.2]
5 [e.sup.-.sub.aq] + [O.sub.2] [right arrow] [O.sup.-.sub.2]
6 [e.sup.-.sub.aq] + [right arrow] [HO.sup.-.sub.2]
[O.sup.-.sub.2] + [OH.sup.-]
7 [e.sup.-.sub.aq] + [HO.sub.2] [right arrow] [HO.sup.-.sub.2]
8 H + H [right arrow] [H.sub.2]
9 H + OH [right arrow] [H.sub.2]O
10 H + [H.sub.2][O.sub.2] [right arrow] OH + [H.sub.2]O
11 H + [O.sub.2] [right arrow] [HO.sub.2]
12 H + [HO.sub.2] [right arrow] [H.sub.2][O.sub.2]
13 H + [O.sup.-.sub.2] [right arrow] [HO.sup.-.sub.2]
14 OH + OH [right arrow] [H.sub.2][O.sub.2]
15 OH + [H.sub.2] [right arrow] [H + [H.sub.2]O
16 OH + [H.sub.2][O.sub.2] [right arrow] [H.sub.2]O +
[H.sub.2]O
17 OH + [HO.sub.2] [right arrow] [H.sub.2]O +
[O.sub.2]
18 OH + [O.sup.-.sub.2] [right arrow] [OH.sup.-] +
[O.sub.2]
19 [HO.sub.2] + [HO.sub.2] [right arrow] [H.sub.2][O.sub.2]
+ [O.sub.2]
20 [HO.sub.2] + [O.sup.-.sub.2] [right arrow] [H.sub.2][O.sub.2] +
[O.sub.2] + [OH.sup.-]
21 [H.sub.2]O [right arrow] [H.sup.+] +
[OH.sup.-]
22 [H.sup.+] + [HO.sup.-.sub.2] [right arrow] [H.sub.2]O
23 [H.sub.2][O.sub.2] [right arrow] [H.sup.+] +
[HO.sup.-.sub.2]
24 [H.sub.+] + [HO.sup.-.sub.2] [right arrow] [H.sub.2][O.sub.2]
25 [H.sub.2][O.sub.2] + [OH.sup.-] [right arrow] [HO.sup.-.sub.2] +
[H.sub.2]O
26 [HO.sup.-.sub.2] + [H.sub.2]O [right arrow] [H.sub.2][O.sub.2] +
[OH.sup.-]
27 H [right arrow] [e.sup.-.sub.aq] +
[H.sup.+]
28 [e.sup.-.sub.aq] + [H.sup.+] [right arrow] H
29 [e.sup.-.sub.aq] + [H.sub.2]O [right arrow] H + [OH.sup.-]
30 H + [OH.sup.-] [right arrow] [e.sup.-.sub.aq] +
[H.sub.2]O
31 OH [right arrow] [H.sup.+] + [O.sup.-]
32 [H.sup.+] + [O.sup.-] [right arrow] OH
33 OH + [OH.sup.-] [right arrow] [O.sup.-] +
[H.sub.2]O
34 [O.sup.-] + [H.sub.2]O [right arrow] [OH.sup.-] + OH
35 [HO.sub.2] [right arrow] [O.sup.-.sub.2] +
[H.sup.+]
36 [O.sup.-.sub.2] + [H.sup.+] [right arrow] [HO.sub.2]
37 [HO.sub.2] + [OH.sup.-] [right arrow] [O.sup.-.sub.2] +
[H.sub.2]O
38 [O.sup.-.sub.2] + [H.sub.2]O [right arrow] [HO.sub.2] +
[OH.sup.-]
39 [O.sup.-] + [H.sub.2] [right arrow] H + [OH.sup.-]
40 [O.sup.-] + [H.sub.2][O.sub.2] [right arrow] [O.sup.-.sub.2] +
[H.sub.2]O
41 OH + [HO.sup.-.sub.2] [right arrow] [OH.sup.-] +
[HO.sub.2]
42 OH + [O.sup.-] [right arrow] [HO.sup.-.sub.2]
43 [e.sup.-.sub.aq] + [right arrow] [O.sup.-] +
[HO.sup.-.sub.2] [OH.sup.-]
44 [e.sup.-.sub.aq] + [O.sup.-] [right arrow] [OH.sup.-] +
[OH.sup.-]
45 [O.sup.-] + [O.sub.2] [right arrow] [O.sup.-.sub.3]
46 [O.sup.-.sub.3] [right arrow] [O.sub.2] + [O.sup.-]
47 [O.sup.-] + [HO.sup.-.sub.2] [right arrow] [O.sup.-.sub.2] +
[OH.sup.-]
48 [O.sup.-] + [O.sup.-.sub.2] [right arrow] [OH.sup.-] +
[OH.sup.-] +
[O.sub.2]
49 [HO.sub.2] + [H.sub.2][O.sub.2] [right arrow] OH + [H.sub.2]O +
[O.sub.2]
50 [O.sup.-.sub.2] + [right arrow] [OH.sup.-] + OH +
[H.sub.2][O.sub.2] [O.sub.2]
Reactions (a) Rate constants (b)
1 [e.sup.-.sub.aq] + 3.48 X [10.sup.9]
[e.sup.-.sub.aq]
2 [e.sup.-.sub.aq] + H 1.73 X [10.sup.10]
3 [e.sup.-.sub.aq] + OH 2.38 X [10.sup.10]
4 [e.sup.-.sub.aq] + 8.84 X [10.sup.9]
[H.sub.2][O.sub.2]
5 [e.sup.-.sub.aq] + [O.sub.2] 1.16 X [10.sup.10]
6 [e.sup.-.sub.aq] + 8.48 X [10.sup.9]
[O.sup.-.sub.2]
7 [e.sup.-.sub.aq] + [HO.sub.2] 8.48 X [10.sup.9]
8 H + H 3.44 X [10.sup.9]
9 H + OH 1.21 X [10.sup.10]
10 H + [H.sub.2][O.sub.2] 3.18 X [10.sup.7]
11 H + [O.sub.2] 9.58 X [10.sup.9]
12 H + [HO.sub.2] 7.24 X [10.sup.9]
13 H + [O.sup.-.sub.2] 7.24 X [10.sup.9]
14 OH + OH 3.76 X [10.sup.9]
15 OH + [H.sub.2] 2.40 X [10.sup.7]
16 OH + [H.sub.2][O.sub.2] 1.79 X [10.sup.7]
17 OH + [HO.sub.2] 9.08 X [10.sup.9]
18 OH + [O.sup.-.sub.2] 7.89 X [10.sup.9]
19 [HO.sub.2] + [HO.sub.2] 3.72 X [10.sup.5]
20 [HO.sub.2] + [O.sup.-.sub.2] 5.84 X [10.sup.7]
21 [H.sub.2]O 2.22 X [10.sup.-6]
22 [H.sup.+] + [HO.sup.-.sub.2] 7.23 X [10.sup.10]
23 [H.sub.2][O.sub.2] 1.34 X [10.sup.-2]
24 [H.sub.+] + [HO.sup.-.sub.2] 3.13 X [10.sup.10]
25 [H.sub.2][O.sub.2] + [OH.sup.-] 7.56 X [10.sup.9]
26 [HO.sup.-.sub.2] + [H.sub.2]O 5.45 X [10.sup.5]
27 H 8.83 X [10.sup.-1]
28 [e.sup.-.sub.aq] + [H.sup.+] 1.88 X [10.sup.10]
29 [e.sup.-.sub.aq] + [H.sub.2]O 5.08 X [10.sup.0]
30 H + [OH.sup.-] 7.77 X [10.sup.6]
31 OH 1.34 X [10.sup.-2]
32 [H.sup.+] + [O.sup.-] 3.13 X [10.sup.10]
33 OH + [OH.sup.-] 7.56 X [10.sup.9]
34 [O.sup.-] + [H.sub.2]O 5.45 X [10.sup.5]
35 [HO.sub.2] 4.21 X [10.sup.5]
36 [O.sup.-.sub.2] + [H.sup.+] 3.13 X [10.sup.10]
37 [HO.sub.2] + [OH.sup.-] 7.91 X [10.sup.9]
38 [O.sup.-.sub.2] + [H.sub.2]O 1.94 X [10.sup.-2]
39 [O.sup.-] + [H.sub.2] 7.95 X [10.sup.7]
40 [O.sup.-] + [H.sub.2][O.sub.2] 3.44 X [10.sup.8]
41 OH + [HO.sup.-.sub.2] 5.17 X [10.sup.9]
42 OH + [O.sup.-] 6.02 X [10.sup.9]
43 [e.sup.-.sub.aq] + 2.19 X [10.sup.9]
[HO.sup.-.sub.2]
44 [e.sup.-.sub.aq] + [O.sup.-] 1.82 X [10.sup.10]
45 [O.sup.-] + [O.sub.2] 2.63 X [10.sup.9]
46 [O.sup.-.sub.3] 6.70 X [10.sup.2]
47 [O.sup.-] + [HO.sup.-.sub.2] 2.84 X [10.sup.8]
48 [O.sup.-] + [O.sup.-.sub.2] 4.26 X [10.sup.8]
49 [HO.sub.2] + [H.sub.2][O.sub.2] 2.90 X [10.sup.-1]
50 [O.sup.-.sub.2] + 9.30 X [10.sup.-2]
[H.sub.2][O.sub.2]
(a) All reactions are second order except for reactions 21, 23, 27, 31,
35, and 46, which are first order.
(b) Second order rate constants are in the unit L [mol.sup.-1]
[s.sup.-1]. First order rate constants are in the unit [s.sup.-1].
Table 2
Model IIIR: G-values of species
Species G-value at 4 [degrees]C (a)
[(mol [J.sup.-1]]
[H.sub.2] 0.4487 x [10.sup.-7]
[H.sub.2][O.sub.2] 0.6817 x [10.sup.-7]
[e.sup.-.sub.aq] 2.6666 x [10.sup.-7]
H 0.5645 x [10.sup.-7]
OH 2.7651 x [10.sup.-7]
[OH.sup.-] 0.4455 x [10.sup.-7]
[H.sup.+] 3.1121 x [10.sup.-7]
[H.sub.2]O -4.5740 x [10.sup.-7]
(a) The number of significant figures is more than is warranted by the
literature values but is needed for computer simulations in order that
the number of H atoms and O atoms in the solution remain constant
throughout a simulation.
Table 3
Simulation predictions and measurements of the production of
[H.sub.2][O.sub.2] caused by the irradiation of water which had been
saturated with a flow of 43 % [H.sub.2] and 57 % [O.sub.2], by volume
Temp. Exptl Irrad. Exptl ([H.sub.2][O.sub.2])
[degrees]C trials min [micro]mol [L.sup.-1]
4 4 15 11.28 [+ or -] 0.08
4 4 30 22.13 [+ or -] 0.17
4 2 60 43.59 [+ or -] 0.36
21 4 15 11.40 [+ or -] 0.11
21 4 30 22.20 [+ or -] 0.36
21 2 60 43.40 [+ or -] 0.01
Temp. IIIR simul. IIIR/exptl.
[degrees]C [micro]mol [L.sup.-1]
4 11.05 0.980
(11.29) (a) (1.001) (a)
4 21.96 0.992
(22.42) (a) (1.013) (a)
4 42.58 0.977
(43.44) (a) (0.997) (a)
21 11.60 1.018
21 23.05 1.038
21 44.62 1.028
(a) The values in parentheses were calculated using predicted values
from simulations for which the rate constants for 4 [degrees]C were used
with the G-values for 21 [degrees]C.
Table 4
Does to reach a heat defect of approximately 0.001 with pure water and
with water containing traces of [O.sub.2]
[O.sub.2] Dose at 21 Dose at 21 Dose at 4
concentration [degrees]C 1 Gy [degrees]C 20 [degrees]C 1 Gy
[min.sup.-1] Gy [min.sup.-1] [min.sup.-1]
mol [L.sup.-1] Gy Gy Gy
[10.sup.-7] 25 37 35
[10.sup.-8] 3 8 18
zero 2 7 3
[O.sub.2] Dose at 4
concentration [degrees]C 20
Gy [min.sup.-1]
mol [L.sup.-1] Gy
[10.sup.-7] 54
[10.sup.-8] 33
zero 28
Accepted: April 1, 2002 (1.) Certain commercial equipment, instruments, or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Research Council of Canada The National Research Council Canada (NRC) is Canada's leading organization for scientific research and development. History NRC was established in 1916, mainly to advise the government. Then, in the early 1930s, laboratories were built in Ottawa. nor the National Institute of Standards and Technology National Institute of Standards and Technology, governmental agency within the U.S. Dept. of Commerce with the mission of "working with industry to develop and apply technology, measurements, and standards" in the national interest. , nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. (2.) The value of G is defined as number of species created, or destroyed, per Joule joule (j  l, joul), abbr. J, unit of work or energy in the mks system of units, which is based on the metric system; it is the work done or energy expended by a force of 1 newton acting through of absorbed dose. The units of G are mol
[J.sup.-1].5. References (1.) N. V. Klassen and C. K. Ross Ross , Sir Ronald 1857-1932. British physician. He won a 1902 Nobel Prize for proving that malaria is transmitted to humans by the bite of the mosquito. . Water calorimetry: the heat defect, J, Res. Natl. Inst. Stand. Technol. 102, 63-74 (1997). (2.) N. V. Klassen and C. K. Ross, Absorbed dose calorimetry using various aqueous solutions, Radiat. Phys. Chem. 38, 95-104 (1991). (3.) N. V. Klassen, K. R. Shortt, and C. K. Ross, Calibration of Fricke dosimetry dosimetry /do·sim·e·try/ (do-sim´e-tre) scientific determination of amount, rate, and distribution of radiation emitted from a source of ionizing radiation, in biological d. by water calorimetry, Proceedings of the Seventh Tihany Symposium symposium In ancient Greece, an aristocratic banquet at which men met to discuss philosophical and political issues and recite poetry. It began as a warrior feast. Rooms were designed specifically for the proceedings. on Radiation Chemistry 1990, Hungarian Chemical Society, Budapest, J. Dobo, L. Nyikos, and R. Schiller, eds. (1991) pp. 543-547. (4.) N. V. Klassen, D. Marchington, and H. C. E. McGowan, [H.sub.2][O.sub.2] determination by the [I.sup.-.sub.3] method and by [KMnO.sub.4] titration titration (tītrā`shən), gradual addition of an acidic solution to a basic solution or vice versa (see acids and bases); titrations are used to determine the concentration of acids or bases in solution. , Anal anal (a´n'l) relating to the anus. a·nal adj. 1. Of, relating to, or near the anus. 2. . Chem. 66, 2921-2925 (1994). (5.) J. S. Laughlin and S. Genna, Calorimetry. Radiation Dosimetry, II, F. H. Attix and W. C. Roesch, eds., Academic (1966) pp. 389-441. (6.) J. P. Seuntjens, I. Kawrakow, and C. K. Ross, Revisiting Convective Motion in Stagnant stagnant /stag·nant/ (stag´nant) 1. motionless; not flowing or moving. 2. inactive; not developing or progressing. Water Calorimeters Operated at Room Temperature., A. J. Williams and K. E. Rosser, eds., Proceedings of NPL 1. NPL - New Programming Language. IBM's original (temporary) name for PL/I, changed due to conflict with England's "National Physical Laboratory." MPL and MPPL were considered before settling on PL/I. Sammet 1969, p.542. 2. Workshop on Recent Advances in Calorimetric Absorbed Dose Standards., National Physical Laboratory, Teddington, U. K. (2000), pp. 103-119. (7.) A. J. Elliot, Rate constants and G-Values for the simulation of the radiolysis of light water over the range 0-300(degrees)C, Technical Report AECL-11073, Atomic Energy of Canada Ltd., Chalk River, Ontario Chalk River is a small town of about 800 people in Ontario 21 km NW of Petawawa, Ontario and 182.15 km NW of Ottawa, Ontario. It is about 15 km from Deep River, Ontario. Chalk River's elementary school is called St. Anthony's. K0J 1J0, Canada (1994). (8.) Oxygen and Ozone, Solubility Data Series Volume 7, R. Battino, ed., Pergamon Press, Oxford (1981). (9.) Hydrogen and Deuterium deuterium (d tēr`ēəm), isotope of hydrogen with mass no. 2. The deuterium nucleus, called a deuteron, contains one proton and one neutron. , Solubility Data Series Volume 5/6, C.
L. Young, ed., Pergamon Press, Oxford (1981).(10.) S. Glasstone, Textbook textbook Informatics A treatise on a particular subject. See Bible. of Physical Chemistry, van Nostrand, New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of (1946). (11.) N. E. Dorsey, Properties of Ordinary Water-Substance, Hafner, New York (1968). (12.) C. K. Ross, J. P. Seuntjens, N. V. Klassen, and K. R. Shortt, The NRC Sealed Water Calorimeter: Correction Factors and Performance, A. J. Williams and K. E. Rosser, eds., Proceedings of NPL Workshop on Recent Advances in Calorimetric Absorbed Dose Standards., National Physical Laboratory, Teddington, U.K. (2000) pp. 90-102. (13.) I. B. Afanas'ev and N. S. Kuprianova, Kinetics kinetics: see dynamics. Kinetics (classical mechanics) That part of classical mechanics which deals with the relation between the motions of material bodies and the forces acting upon them. and mechanism of the reactions of the superoxide superoxide /su·per·ox·ide/ (-ok´sid) any compound containing the highly reactive and extremely toxic oxygen radical O2-, a common intermediate in numerous biological oxidations. su·per·ox·ide n. ion in solution. II The kinetics of protonation protonation (prō`tənā'shən), in chemistry, addition of a proton to an atom, molecule, or ion. The proton is the nucleus of the hydrogen atom; the positive hydrogen ion, H+, consists of a single proton. of the superoxide ion by water and ethanol ethanol (ĕth`ənōl') or ethyl alcohol, CH3CH2OH, a colorless liquid with characteristic odor and taste; commonly called grain alcohol or simply alcohol. . Int. J. Chem. Kinetics 15, 1057-1062 (1983). (14.) D. H. Chin, G. Chiericato Jr., E. J. Nanni Jr., and D. T. Sawyer, Proton-induced disproportionation Disproportionation or dismutation is used to describe two particular types of chemical reaction:[1]
(15.) A. J. Elliot, M. P. Chenier, and D. C. Ouellette, Temperature dependence of g values for [H.sub.2]O and [D.sub.2]O irradiated with low linear energy transfer radiation, J. Chem. Soc., Faraday faraday /far·a·day/ (F ) (far´ah-da) the electric charge carried by one mole of electrons or one equivalent weight of ions, equal to 9.649 × 104coulombs. far·a·day n. Trans. 89, 1193-1197 (1993). (16.) A. W. Boyd, M. B. Carver carver /car·ver/ (kahr´ver) a tool for producing anatomic form in artificial teeth and dental restorations. carver (carving instrument), n , and R. S. Dixon, Computed and experimental product concentrations in the radiolysis of water radiolysis of water (rādēōl´isis), n a separation of water via radioactive activity. The end result is the production of hydrogen peroxide. , Radiat. Phys. Chem. 15, 177-185 (1980). (17.) A. Krauss and M. Roos, Heat conduction Heat conduction or thermal conduction is the spontaneous transfer of thermal energy through matter, from a region of higher temperature to a region of lower temperature, and hence acts to even out temperature differences. , convection and radiolysis of the [H.sub.2]/[O.sub.2] system in the water absorbed dose calorimeter, Thermochim, Acta 310, 53-60 (1998). (18.) C. E. Rogers, Permeation per·me·a·tion n. The process of spreading through or penetrating, as in the extension of a malignant neoplasm by continuous proliferation of the cells along the blood or lymph vessels. of gases and vapours in polymers. Polymer Permeability, J. Comyn, ed., Elsevier Applied Science Publishers, London (1985) pp. 11-73. (19.) P. Jeroschewski and D. z. Linden Linden, city, United States Linden, city (1990 pop. 36,701), Union co., NE N.J., in the New York metropolitan area; inc. 1925. During the first half of the 20th cent. , A flow system for calibration of dissolved oxygen sensors An oxygen sensor is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed. It was developed by Robert Bosch GmbH during the late 1960s under supervision by Dr. Günter Bauman. , Frescnius' J. Anal. Chem. 358, 677-682 (1997). (20.) S. R. Domen, An absorbed dose water calorimeter: theory, design, and performance, J. Res. Natl. Bur. Stand. (U.S.) 87, 211-235 (1982). (21.) C. K. Ross, N. V. Klassen, and G. D. Smith, The effect of various dissolved gases on the heat defect of water, Med. Phys. 11, 653-658 (1984). |
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