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At least 19 recordsLinked to original sources
PubMed1996

[A study on the control of air toxic chemicals in workplace for bakelite manufacturing and casting].

Air concentrations of phenol, formaldehyde and ammonia related to the contents of free phenol, formaldehyde in raw material, and solidifying agent-urotropine in bakelite. Due to the solubility of phenol and formaldehyde, in the manufacture process, water was added to lower contents of phenol and formaldehyde in bakelite, and content of urotropine was reduced in bakelite sand presceription to lower air concentrations of phenol, formaldehyde and ammonia. As contents of phenol and formaldehyde in bakelite reduced to 4.9% and 0.037% from 6.32% and 0.062%, respectively, air concentrations of phenol, formaldehyde and ammonia lowered to 0.61 mg/m3, 0.69 mg/m3, and 5.1 mg/m3 from 2.94 mg/m3, 1.72 mg/m3, and 12.9 mg/m3, respectively, and incidence rate of skin disease in the employees of the workplace decreased to zero from 80.2%. It is recommended that a hygienic standard for allowable concentration of mixed toxic chemicals in the workplace air for bakelite manufacturing be formulated as soon as possible.

Air Pollutants, Occupational↗
PubMed2002

[Extraction and gas chromatographic analysis of residual trimethylamine(TMA) in the bakelite-type macromolecule complex material].

A method for the determination of residual TMA in the bakelite-type macromolecule complex material has been established. The whole process includes sample pretreatment, TMA extraction and GC analysis. After the samples have been pretreated, the TMA in them was extracted at (38 +/- 2) degrees C for 16 hours. Then the content of TMA in the liquid can be determined directly. From the experimental results we can conclude that the whole method is cheap, simple and accurate. It meets the requirement of microanalysis and can be used to determine real samples.

Air Pollutants↗
PubMedDate not supplied

Can the AAPM Task Group 21 protocol lead to optimum ion chamber designs?

The recently published AAPM Task Group 21 protocol for high-energy dosimetry is complicated in that it requires the physicist to obtain the values of about a dozen different physical variables by looking them up in tables or graphs. This should be compared with the procedure of earlier protocols using the concept of a single multiplier C lambda. We have investigated how the physical principles outlined in the improved AAPM protocol could be utilized for the redesign of the therapy-level ion chambers in such a way that one can reduce the number of factors that need to be looked up in tables or graphs for the calibration of high-energy teletherapy photon beams. In our analysis presented in this paper we found that one such design could be for an ion chamber having a wall acrylic or Bakelite of a thickness not exceeding 0.1 g/cm2 and having an inner diameter of 6 mm, and used in conjunction with a cobalt-60 buildup cap of thickness 0.35 g/cm2 made of acrylic, Bakelite, or Tufnol. If a chamber of such a design is used in a water phantom, the dosimetry practically reduces to the simplicity of the former protocols of depending on a single value of energy-dependent multiplier to be obtained from a table. With the above design parameters, it becomes possible to eliminate the explicit need to incorporate the factors Pwall, Prepl, Awall, beta wall, and the variable alpha, representing the fraction of ionization due to electrons from the wall material of the chamber.

Animals↗
PubMed2003

Development of a computer model using the EGS4 simulation code to calculate scattered X-rays through some materials.

In this paper a computer model based on the use of the well-known Monte Carlo simulation code EGS4 was developed to simulate the scattering of polyenergetic X-ray beams through some materials. These materials are: lucite, polyethylene, polypropylene and aluminium. In particular, the ratio of the scattered to total X-ray fluence (scatter fraction) has been calculated for X-ray beams in the energy region 30-120 keV. In addition scatter fractions have been determined experimentally using a polyenergetic superficial X-ray unit. Comparison of the measured and the calculated results has been performed. The Monte Carlo calculations have also been carried out for water, bakelite and bone to examine the dependence of scatter fraction on the density of the scatterer. Good agreement (estimated statistical error < 5%) was obtained between the measured and the calculated values of the scatter fractions for materials with Z < 20 that were studied in this paper.

Absorptiometry, Photon↗