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At least 1,423 records · Page 79Linked to original sources
PubMed1984

[Pressure control of a pressurized proportional counter for 4 pi beta-gamma coincidence counting--effects of pressure variation and study of a non-flow type system].

Effects of the pressure variation of counting gas on the efficiency function were examined using a 4 pi beta-gamma coincidence counting system with a pressurized proportional counter. The results showed that the pressure variation of about ten kPa could not give large effects on the efficiency function and that a non-flow type of pressurized proportional counter with a simple gas control system could work well in the case of the pressure higher than 1 MPa, an ordinary pressure for the counting.

Beta Particles↗
PubMed1985

Energy response of a thermoluminescent lithium fluoride disc dosimeter to beta-rays.

In order to eliminate some drawbacks of thin detector with suitable window for measuring radiations of low penetrating power, the thermoluminescent LiF disc dosimeter was fabricated from phosphor of LiF with activators of magnesium and copper and inorganic binder of silica and alumina. The energy response of the LiF disc dosimeters to beta-rays was investigated by comparing with theoretical calculations and measurements with a parallel-plate ionization chamber. From the results obtained, the LiF disc dosimeter significantly underestimated the doses for low beta-ray energy (below 0.3 MeV), while its reading agreed well with the calculated ones for high energy (above 0.8 MeV). Nevertheless, it is suggested that the fabricated LiF disc dosimeter is useful to evaluate the skin dose from the practical point of view, since beta-ray less than 0.6 MeV is completely absorbed before reaching the skin covered with clothing.

Beta Particles↗
PubMedDate not supplied

The influence of ionizing radiation on spore germination and emergent hyphal growth response reactions of microfungi.

The accident at the Chernobyl Atomic Energy Station resulted in radiation contamination of large tracts of land and particularly the reactor building itself. Sustained exposure of microfungi to radiation appears to have resulted in formerly unknown adaptive features, such as directed growth of fungi to sources of ionizing radiation. We evaluate here spore germination and subsequent emergent hyphal growth of microfungi in the presence of pure gamma or mixed beta and gamma radiation of fungi isolated from a range of long term background radiation levels. Conidiospore suspensions were exposed to collimated beams of radiation and percent spore germination and length of emergent hyphae were measured. All fungal species isolated from background radiation showed inhibition or no response in germination when irradiated. Isolates from sites with elevated radiation showed a stimulation in spore germination (69% mixed radiation and 46% for gamma irradiation). Most isolates from low background radiation sites showed a significant reduced or no response to exposure to either source of radiation, whereas the stimulatory effect of experimental exposure to radiation appeared to increase in magnitude as prior exposure to radiation increased. We propose that the enhanced spore germination and hyphal growth seen in the exposure trials is induced by prior long term exposure to radiation and these factors could be important in controlling the decomposition of radionuclide-bearing resources in the environment.

Beta Particles↗
PubMed1999

Compounds labelled with short-lived beta(+)-emitting radionuclides and some applications in life sciences. The importance of time as a parameter.

Some examples of recent development of the synthesis of compounds labelled with short-lived beta(+)-emitting radionuclides will be discussed with an emphasis on the importance of time in selecting a synthetic strategy. Furthermore the use of such labelled compounds to monitor certain processes in areas within the field of analytical chemistry and in various applications in drug development will be presented.

Animals↗
PubMed2002

Assessment of the potential for Listeria monocytogenes survival and growth during alfalfa sprout production and use of ionizing radiation as a potential intervention treatment.

Alfalfa seeds (Australian, nondormant, nonscarified) were treated with 20,000 ppm active chlorine, sprouted in canning jars for 5 days, and packaged and stored at 5 degrees C for up to 9 days. Seeds or sprouts were inoculated with a three-strain cocktail of Listeria monocytogenes at one of three points during the process-day 0 (before 24-h aqueous seed soak), day 1 (after 24-h aqueous seed soak), or day 5 (after sprouting, before prepackaging 10 ppm chlorine rinse)--or control (no inoculum), and the ability of the inoculum to survive and grow was evaluated. Total bacterial numbers on uninoculated seeds increased dramatically during the first 24-h the seeds were soaked, from 3.5 to ca. 8.0 log CFU/g, and remained at this level during refrigerated storage. When the seeds were inoculated with a cocktail of L. monocytogenes (log 5 CFU/10 ml) on day 0 or 1, the population of the pathogen increased dramatically, to within 1 to 2 logs of the total, and remained high during refrigerated storage. When sprouted seeds were inoculated with L. monocytogenes later in the process (day 5), the inoculum survived but did not grow more than ca. 1 log CFU/g, regardless of whether the inoculation level in each jar was low (10(3)) or high (10(5)). Irradiation of sprouts with beta radiation at 3.3 or 5.3 kGy, but not 1.5 kGy, was effective at eliminating L. monocytogenes from inoculated sprouts (6 log CFU/g) without causing noticeable changes in appearance or odor. In summary, L. monocytogenes can grow on sprouts during production, can survive on refrigerated sprouts, and may be eliminated on sprouts with beta radiation.

Beta Particles↗
PubMed2006

Effect of gamma or beta radiation on Salmonella DT 104 in ground pork.

Mixtures of six Salmonella Typhimurium DT 104 strains were inoculated into three ground pork products to determine the effect of fat content on the radiation resistance of Salmonella DT 104. The ground pork products were 90% lean, 50:50 fat:lean, and 100% fat. Inoculated products were irradiated using a gamma radiation source in a self-contained 137Cesium irradiator or a 10 MeV accelerator producing electrons (e-beam). The radiation D10-values (dose required for a 90% inactivation of viable CFU) for Salmonella DT 104 inoculated into 90% lean ground pork, 50:50 fat/lean ground pork, and 100% pork fat and subjected to beta radiation were 0.42 kGy, 0.43 kGy, and 0.43 kGy, respectively. The corresponding radiation D10-values for Salmonella DT 104 subject to gamma radiation were 0.56, 0.62, and 0.62 kGy, respectively. There was no statistical significant difference (P = 0.3) in radiation D10-values for Salmonella in the three products subject to either radiation treatment. Therefore, fat content had no effect. There was a significant difference (P = 0.001) between the radiation D10-values obtained with the two radiation sources. The radiation D10-values were within the reported range for irradiation destruction of Salmonella contaminated raw meat products.

Animals↗
PubMedDate not supplied

Hemophilic arthropathy.

The most common clinical manifestation of hemophilia is arthropathy secondary to recurrent hemarthroses and chronic synovitis. Joint-surface erosions secondary to chronic synovitis often occur in early childhood and progress to advanced arthropathy by late adolescence. The knee, elbow, ankle, hip, and shoulder are the most commonly involved joints. Management of hemophilic arthropathy has advanced with the development of purified clotting factor concentrates and procedures to prevent chronic synovitis. Radiosynovectomy using beta particle-emitting radiocolloids has been effective in dramatically reducing the frequency of hemarthroses and resolving chronic synovitis. The most common surgical procedures used to manage hemophilic arthropathy are synovectomy, joint debridement, fusion, and joint arthroplasty. Late infection and arthrofibrosis complicate joint arthroplasty more often in these patients than in patients with other forms of arthritis. The high incidence of late infection may relate to frequent intravenous self-infusion of clotting factor combined with immune suppression. Despite the medical and surgical complexities of hemophilic arthropathy, orthopaedic procedures have a high incidence of patient satisfaction.

Autoantibodies↗
PubMed1988

[Estimation of absorbed dose of beta radiation into the critical tissues by a single injection of tritiated water].

The biological effects of tritium in humans need to be clarified, because the chances of humans becoming exposed to tritium beta radiation may increase with the development of the nuclear fusion reactor. To evaluate the biological effects of tritium, it is necessary to estimate exactly the absorbed dose from the tritium beta rays in the tissue. In many reports, the absorbed dose of HTO in the tissues is estimated from the tritium content in body fluid and dose calculations are customarily based upon the water content of soft tissues, which is taken to be 0.7 to 0.8. However, these methods may not show the exact absorbed dose in the organs. In the present study, the radioactivity of the critical tissues was measured directly using a sample oxidizer and the absorbed dose was calculated from the radioactivity of tritium in the tissues. Details on the method for calculation of the absorbed dose in tissues of the mouse is shown in this report. The results suggest that the absorbed dose should be obtained from the radioactivity in the tissues.

Absorption↗