We present a systematic study of the heating and pre-sintering behavior of porous copper powder metal compacts. We employ a TE102 single mode microwave system to position the samples in the separated electric field (E) or magnetic field (H) anti-node of the cavity. We observe significant differences in the heating, pre-sintering, and microstructure evolution of the samples due to the individual fields. We note that sample history (whether heated first in the E-field or H-field) greatly effects a difference in heating trends and subsequent heating behavior and does not appear to be solely a thermal process.
The use of chlorinated water in swimming pools produces elevated chloroform levels in the water and air of the pools which can cause chloroform body burden of swimming individuals. Present study confirmed the chloroform body burdens from a 40-min swimming and evaluated the decay of chloroform breath concentration after the cessation of a 60-min swimming. Air and water concentrations were measured in the pools. The water and air chloroform concentrations ranged from 18.1 to 25.3 ㎍/ℓ and from 30.9 to 60.7 ㎍/㎥ for the confirmation study, respectively. The breath level after 40-min swimming was about 64 to 266 folds higher than the corresponding background breath. The breath concentration after the 40-min swimming ranged from 10.5 to 21.3 ㎍/㎥, while that prior to the corresponding swimming ranged from 0.07 to 0.19 ㎍/㎥. In addition, the post-exposure breath level varied with the subjects who swam in the pool on the same visiting day. Breath concentration increased gradually during 60-min swimming, then decreased rapidly within 5 minutes after the cessation of exposure, after that, decreased slowly, and finally approached to a background breath level at 1-2 hr after exposure.
To perform a long-term ambient sampling study at a residential site, an air sampler was constructed to collect 24-hour integrated air samples suitable for the volatile organic compounds (VOCs) analysis. It includes an esthetically acceptance due to proximity to homes, as well as providing the required sampling specifications. The VOCs sampler accomodates four 5/8 stainless steel(SS) traps packed with adsorbent(Tenax) and is capable of four flow rates in the range of 5 to 50 cc/min. Sintered metal filters(10 micrometer) were directly connected to the inlet of the trap adapters. Additional specifications include: 1) constructed of organically inert materials. 2) weatherproof, 3) battery operated, 4) collecting of VOCs at a breathing zone level, , and 5) quiet operation with micro diaphragm pumps wrapped by the sponge. The pump/battery system was separated from the sampling shelter. Sound levels measured for this system were below permissible sound levels (NJDEP) at a residential site. The sampler has been successfully operated at both ground level in a residential area and on the roof of a one story elementary school.