Two-stage-type electrostatic precipitator re-entrainment phenomenaunder diesel flue gases

One of the applications of the electrostatic precipitator (ESP) is the cleaning of air to increase the visibility index in highway tunnels. Particles floating in air in highway tunnels are mainly carbon. Collection efficiency of a large particle diameter in an ESP often decreases when the ESP collects carbon particles which have low electric resistance. Collection efficiency often becomes negative in an experimental ESP. The negative collection efficiency means that the particle concentration flowing downstream is greater than that upstream in the ESP. This phenomenon is explained as the re-entrainment of particles. In this paper, experiments were carried out to investigate the cause of the decrease in efficiency of particle collection of the ESP. The time characteristic of the collection efficiency and the distribution of particle size on the collection electrodes were studied. Experimental results showed that the decrease in the collection efficiency was caused by re-entrainment of particles during the ESP operation. The effect of gas-flow velocity on the collection efficiency of the ESP was also investigated to study the cause of re-entrainment phenomena. The result showed that the re-entrainment phenomena depended on the gas-flow velocity     

Agglomeration of particles by ac corona discharge

Improving the collection efficiency for particles smaller than 1 μm on every precipitator is important. We sought to improve the collection of these particles on an ESP due to particle agglomeration. Particles are charged by ac corona discharge in a precharger and agglomerated by a dc electric field in an agglomerator downstream of the precharger. Diesel exhaust particles were used as particulate matter for the experiments. The distribution of particle size was measured using a particle counter and a scanning electron microscope. By these methods, particles as small as 0.01 μm could be counted. Results showed the agglomeration between particles at ac corona discharge operating mode. The concentration of particles smaller than approximately 0.35 μm decreases, and that of particles larger than approximately 0.35 μm increases in the agglomerator. The agglomeration rate increases with increasing applied voltage, then saturates. These results may be due to the size distribution and to decrease of concentration by agglomeration. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 30–37, 2000     

Serum globulin levels and activities of daily living in centenarians

Serum globulin levels in 101 centenarians (77 women, 24 men) were analyzed by zonal electrophoresis and immunoglobulin assays. Six subjects showed an M band in electrophoretograms. Five M bands were immunoglobulin G (IgG) type and one was IgA. One subject was suspected to suffer from IgG-type multiple myeloma, and the others were thought to have essential (benign) monoclonal gammopathy. The relationship between serum globulin levels and activities of daily living (ADL) was studied in remaining 95 subjects. There were 21 rank-J (free-living), 25 rank-A (unable to go outside without help), 23 rank-B (bedridden but able to sit on the bed), and 26 rank-C (completely bedridden) centenarians. The mean serum alpha 1-, alpha 2-, and beta-globulin level in the rank-J centenarians was at the upper limit of the normal adult range. The mean alpha 1-globulin levels in rank-B (3.3 +/- 0.4%) and C (3.4 +/- 0.5%) subjects were significantly higher than those in rank-J (2.9 +/- 0.3%) centenarians. The mean serum gamma-globulin level of rank-J centenarians (16.9 +/- 3.7%) was within the normal range. The mean gamma-globulin levels in rank-B (21.0 +/- 2.7%) and C (22.8 +/- 4.9%) subjects were significantly higher than that in rank-J centenarians. The mean immunoglobulin G concentrations in rank-B (1.620 +/- 304 mg/dl) and C (1.720 +/- 392 mg/dl) subjects were significantly higher than those in rank-J centenarians (1.320 +/- 361 mg/dl) and in normal adults (1.150 +/- 235 mg/dl). IgA concentrations in all centenarians were higher than in normal controls. There was no significant difference in IgA or IgM concentration between rank-J subjects and those in other ranks. Serum globulin levels measured with electrophoresis, and the immunoglobulin concentrations, can be valuable indicators of the ability to perform activities of daily living, and may be useful predictors of subclinical diseases or morbidity in centenarians.     

Serum albumin level and activities of daily living in centenarians

The relationship between serum albumin level and activities of daily living was studied in 95 centenarians. There were 73 women (12 rank J: free-living, 18 rank A: unable to go outside without help, 20 rank B: bedridden but able to sit on the bed, 23 rank C: completely bedridden) and 22 men (9 rank J, 7 rank A, 6 rank B or C). The serum albumin level (mean +/- S.D. 4.0 +/- 0.4 g/dl) of the rank J women was at the lower limit of normal for young adults. The albumin levels of rank A, rank B, and rank C were 3.7 +/- 0.4 g/dl, 3.5 +/- 0.3 g/dl, and 3.4 +/- 0.4 g/dl, respectively. The levels of rank B and rank C women were significantly lower than that of rank J women. The albumin level of rank J men (3.9 +/- 0.3 g/dl) was lower than that of young adults. The albumin level of ranks B and C men (3.1 +/- 0.3 g/dl) was significantly lower than that of rank J men. The A/G ratio or albumin fraction (%) measured by serum electrophoresis was similar to that of the serum albumin level of centenarians of both sexes. There were no significant differences in the serum protein level or in the peripheral hemoglobin level between rank J centenarians and those of other ranks, for both sexes. The serum albumin level is a valuable indicator of the ability to perform activities of daily living and may be a useful prognostic index in centenarians.     

Determination of hepatitis delta virus (HDV)-RNA in asymptomatic cases of HDV infection

OBJECTIVES: To assess the frequency of hepatitis delta virus (HDV) viremia in asymptomatic cases of HDV infection and the clinical significance of the HDV viremia, we conducted a cross-sectional, community-based study. METHODS: Of 2207 examinees, 210 (9.5%) were found to be positive for hepatitis B surface antigen (HBsAg). Antibody to HDV was detected in 47 (22.4%) of the 210 examinees, and 43 of the 47 were further evaluated for serum HDV-RNA by polymerase chain reaction. RESULTS: Twenty-one (48.8%) of the 43 had detectable levels of HDV-RNA in serum, and 22 (51.2%) were negative for serum HDV-RNA. The majority (61.9%) of the HDV-RNA-positive HBsAg carriers had high levels of serum ALT. In contrast, the frequency of an abnormally high level of serum ALT was only 9.1% in the HBsAg carriers positive for HDV antibody but negative for HDV-RNA, and the frequency did not differ from that seen in the HBsAg-negative individuals. The semiquantified HDV-RNA levels did not correlate with the serum ALT levels. CONCLUSION: Seropositivity of HDV-RNA was strongly associated with liver cell damage, even in asymptomatic cases. The absence of a detectable level of serum HDV-RNA might be related to previous HDV infection.