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Gas Storage in Metal–Organic Frameworks
Published in T. Grant Glover, Bin Mu, Gas Adsorption in Metal-Organic Frameworks, 2018
Darren P. Broom, Jacob W. Burress
For gravimetric measurement, the accuracy of the microbalance fundamentally limits the accuracy of an adsorption measurement; although, in practice, long-term stability is the most important factor. If, for instance, the microbalance has sub-microgram resolution and is calibrated correctly, but the reading drifts with time, it is the magnitude of the drift that is important, not the measurement resolution. Testing the microbalance stability under conditions where no adsorption is likely to occur, for example, for helium at room temperature, is therefore important to establish the susceptibility of the microbalance to drift and random variation.
Data-driven optimization of manufacturing processes
Published in S. Thirumalai Kumaran, Tae Jo Ko, S. Suresh Kumar, Temel Varol, Materials for Lightweight Constructions, 2023
T. Ramkumar, M. Selvakumar, S. K. Ashok, M. Mohanraj
The test surface of the wear specimens was made flat by mechanical polishing and cleaned using acetone. The wear surface of the samples and wear track are cleaned using acetone and weighed using a microbalance before and after each test. The microbalance has an accuracy of +0.0001 gm. The wear samples are held against the rotating disc by applying the load and adjusting the sliding speed. The procedure is repeated for all the samples by keeping the test parameters constant. The calculated mass loss, wear rates, and specific wear rates of the samples are shown in Table 10.1.
Design and qualification of a bench-scale model for municipal waste-to-energy combustion
Published in Journal of the Air & Waste Management Association, 2022
Robert J. Giraud, Philip H. Taylor, R. Bertrum Diemer, Chin-Pao Huang
While methanol can be fed continuously, pyrolysis and gasification via the pyroprobe is effectively a batch operation, requiring establishment of targets for test material mass and experimental run duration. Readable to 1 µg, the microbalance was capable of measuring 100 µg of test material loaded into a pyroprobe cartridge. Monitoring requirements for full-scale waste-to-energy plants (EPA 2018a) point to 15 minutes as a minimum run duration. With this as a minimum along with a typical European value for full-scale flue gas (prior to air pollution control) HF concentration of 10 mg Nm−3 (Kamuk 2009) in mind, a duration of 16 minutes corresponds to combustion of 100 µg of PTFE. Hence, 16 minutes was set as the run duration. With run duration set, TGA results for a test material provide the basis for pyroprobe temperature programming to assure continuous gasification of a nominal 100 µg batch of material over the course of the run.
Particle transfer and adherence to human skin compared with cotton glove and pre-moistened polyvinyl alcohol exposure sampling substrates
Published in Journal of Environmental Science and Health, Part A, 2021
Aleksandr B. Stefaniak, Eleanor E. Wade, Robert B. Lawrence, Elizabeth D. Arnold, M. Abbas Virji
A microbalance (Model XS205 Dualrange, Mettler Toledo) capable of reading to 10 µg was used to prepare all powder samples. The microbalance was calibrated using its internal standard at the start of each sampling day and immediately verified using an independent ASTM Class 1 calibration weight (Denver Instrument, Bohemia, NY, USA). To ensure reproducible powder sample masses and levels for each contact, metal hardware washers (17 mm inner diameter, 2 mm thickness) were used to limit the spread of powder across a substrate. Briefly, a clean dry washer was glued (Gorilla Glue, The Gorilla Glue Company, Sharonsville, OH, USA) to a test surface, the glued assembly weighed on the calibrated microbalance, and the appropriate mass of Al2O3 powder added to the well created by the washer on the surface. Note that this well ensured reproducible experimental conditions; however, it effectively reduced the area for palm skin contact from 4 cm2 (area of hole in contact plate of the hand bracket) to 2.26 cm2 (area of the well). Three types of surfaces were evaluated: glass as a smooth surface (Cat. No. 12-544-4, 75 mm x 25 mm microscope slides, Fisher Scientific, Pittsburgh, PA, USA), sanded wood as a semi-rough surface (Cat. No. 10049505, 1.5-inch diameter woodcraft disks, ArtMinds®, The Michaels Companies, Irving, TX, USA), and coarse-grit sandpaper as a rough surface (60 grit, Ace Hardware, Oak Brook, IL, USA). Three masses of Al2O3 powder were evaluated, nominally 0.1, 0.2, and 0.4 g. These masses correspond to simulated surface contamination levels of 44, 88, and 177 mg/cm2, respectively. The contamination level that corresponded to the 0.1 g applied load approximated levels of metal contamination observed in a hard metal production facility;[20] the higher masses were chosen as a factor of two progression to test the influence of this variable.