Active Masses Breathing

This is the change in the active masses volume (active mass breathing). Oxidized and reduced forms do not usually have the same volumetric density. This may cause a defect in electronic percolation and loss of active mass. The lower the difference in density, the higher the cyclability. Usually, proton and lithium intercalation compounds have low volumetric variation on cycling. 

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D. Pavlov, and E. Bashtavelova, Structural Properties of the PbOj Active Mass Determining Its Capacity and the Breathing of the Positive Plate during Cycling, J. Electrochem. Soc.. 133 (1986), 241. 

Many researchers have attempted to determine mercury levels in the blood, urine, tissues, and hair of humans and animals. Most methods have used atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), or neutron activation analysis (NAA). In addition, methods based on mass spectrometry (MS), spectrophotometry, and anodic stripping voltametry (ASV) have also been tested. Of the available methods, cold vapor (CV) AAS is the most widely used. In most methods, mercury in the sample is reduced to the elemental state. Some methods require predigestion of the sample prior to reduction. At all phases of sample preparation and analysis, the possibility of contamination from mercury found naturally in the environment must be considered. Rigorous standards to prevent mercury contamination must be followed. Table 6-1 presents details of selected methods used to determine mercury in biological samples. Methods have been developed for the analysis of mercury in breath samples. These are based on AAS with either flameless (NIOSH 1994) or cold vapor release of the sample to the detection chamber (Rathje et al. 1974). Flameless AAS is the NIOSH-recommended method of determining levels of mercury in expired air (NIOSH 1994). No other current methods for analyzing breath were located. 

The UBT is based on HP urease activity. The carbon (nonradioac-tive isotope) and " carbon (radioactive isotope) tests require that the patient ingest radiolabeled urea, which is then hydrolyzed by HP (if present in the stomach) to ammonia and radiolabeled bicarbonate. The radiolabeled bicarbonate is absorbed in the blood and excreted in the breath. A mass spectrometer is used to detect carbon, whereas " carbon is measured using a scintillation counter. The stool antigen test is approved by the Food and Drug Administration (FDA), but availability in the United States is limited. It is less expensive and easier to perform than the UBT, and may be useful in children. Although comparable to the UBT in the initial detection of HP, the stool antigen test is less accurate when used to confirm HP eradication posttreatment. Salivary and urine antibody tests are under investigation. ... 

There are different kinds of DAFC operation conditions depending of the way the fuel and the oxidant (oxygen/air) are fed into the cell. In complete active fuel cells the liquid fuel (neat alcohol or aqueous solution) is pumped and gas is compressed, using auxiliary pumps and blowers, in order to improve mass transport and reduce concentration polarization losses in the system. On the other hand, in complete passive DAFC the alcohol reaches the anode catalyst layer by natural convection and the cathode breathes oxygen directly from the air. A number of intermediate options have been also studied and tested. 

The air malce up in the aeration tank is designed to meet the need for dissolved oxygen (around 2 mgd" ) to satisfy the BOD5 and so diat the bacterial mass can breathe. It is also designed to contribute to stirring and keeping the activated sludge in suspension. 

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