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Thermochemistry, Electrochemistry, and Solution Chemistry
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
e quantity given in this table is -dil H, the negative of the enthalpy (heat) of dilution to in nite dilution for aqueous solutions of several common acids; i.e., the negative of the enthalpy change when a solution of molality m at a temperature of 25 °C is diluted with an in nite amount of water. e tabulated numbers thus represent the heat produced (or, if the value is negative, the heat absorbed) when the acid is diluted from the initial molality m to in nite dilution. It is sometimes useful to have the dilution ratio, which is the number of moles of water that must be added to one mole of acid to produce a solution of desired molality. is may be calucalated from the relation: dilution ratio = 55.506/m, where m is in mol/kg.
Short-range bioaerosol deposition and recovery of viable viruses and bacteria on surfaces from a cough and implications for respiratory disease transmission
Published in Aerosol Science and Technology, 2021
C. T. Wang, S. C. Fu, Christopher Y. H. Chao
For the E. coli experiment, the E. coli was cultured in advance in Tryptone soya broth (TSB) solution for 24 h in an incubator at a temperature of 37 °C. Then the E. coli solution was centrifuged at 4,000 RPM for 15 min to obtain E. coli pellets. The E. coli pellets were then resuspended in 200 mL artificial saliva solution. The E. coli concentration of the final solution for cough generator was 107 CFU/mL.Serial dilution was conducted to dilute the E. coli solution. Then, pour plate method was used to measure the E. coli concentration in a solution. First, target E. coli solution of 1 mL was transferred into a petri dish by a pipette. Then, melted sterilized Tryptone soya agar (TSA) solution of around 25 mL with temperature of around 52 °C was poured into the same petri dish. The solution was mixed by gentle shaking in the petri dish and the solution was then solidified by cooling to room temperature. Then the petri dish was inverted, sealed by the parafilm, and put in an incubator at a temperature of 37 °C for around 24 h. Then, the colony forming units (CFUs) on the petri dish were counted. The E. coli concentration in initial solution could be calculated by the CFU number on plate and the corresponding dilution ratio.
Flotation of oxidized coal using coal tar as a new collector
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zili Yang, Qi He, Guohui Chang, Yangchao Xia, Ming Li, Yaowen Xing, Xiahui Gui
The compositions of DO and HTCT were determined semi-quantitatively by conducting GC/MS (QP2010 ULTRA, Shimadzu, Japan). In general, the asphaltenes in HTCT are various polymers with high molecular weights and high melting points that are difficult to detect via GC/MS. Therefore, for the HTCT composition, only the results of volatile components with melting points less than 300°C, such as low molecular mass aliphatic and aromatic compounds, are reported here. Before the test, the collector sample was diluted with dichloromethane at a dilution ratio of 20:1 by volume. The GC/MS working parameters are as follows: high-purity helium (99.999%) was used as the carrier gas at a flow rate of 1 mL/min; the temperature of the oven was increased from 20 to 300°C at a speed of 10°C/min and maintained at 300°C for 10 min. The relative content of each component was determined by the peak area normalization method.
The Aitken counter: Revisiting its design and performance characteristics
Published in Aerosol Science and Technology, 2020
Dylan Leigh-Manuell, Philip K. Hopke, Suresh Dhaniyala
The PAC operation requires selection of a dilution ratio and this choice is dependent on the expected particle concentration. Ideally, the performance of the instrument would be independent of the choice of dilution ratio. To test instrument performance under different dilution ratios, we used DMA-generated 110 nm ammonium sulfate particles, corresponding to the cut-point size found in the previous experiment. The particle concentrations were measured by the TSI CPC and the PAC. The PAC was operated under different dilutions available in the instrument, 1/5 or 15 cm3 sample air, 1/10 or 7.5 cm3 sample air, 1/20 or 3.75 cm3 sample air, 1/50 or 1.5 cm3 sample air, 1/200 or 0.375 cm3 sample air, and 1/1000 or 0.075 cm3 sample air. The efficiency of the PAC under these different operations is shown in Figure 7. The efficiencies were consistently about 50% for the low dilution ratios of 1/5, 1/10, and 1/20, while they varied widely for the high dilution ratios of 1/50, 1/200, and 1/1000. We, thus, believe that measurements with the PAC were more precise under conditions of low concentrations than high concentrations.