Search

In this paper, we report the preparation of polyethylene composites with organically modified montmorillonite. Three different Na+-montmorillonites were modified in order to obtain organoclays and two grades of high-density polyethylene were used as composite matrices. All composites were prepared by melt blending, and their physical and mechanical properties were thoroughly characterized. The extent of clay platelet exfoliation in the composites was confirmed by X-ray diffraction (XRD). Mechanical properties under static and impact conditions were evaluated to assess the influence of the reinforcement on the properties of polyethylene.

No abstract available.

The intake and retention of 89Sr and 90Sr from airborne particles were estimated for eight infants, ranging in age from 1 to 9 months, during the period April-July 1963. These infants are a part of a more extensive study to measure retention of 90Sr, other radionuclides, and stable elements entering the body under normal environmental conditions by ingestion from food and water and inhalation from air. Levels of 89Sr and 90Sr were measured in airborne particles, water and prepackaged baby foods. The amounts of these radionuclides inhaled as airborne particles and retained were computed from the concentration of 89Sr and 90Sr in airborne particles, and from the amounts of these radionuclides that were ingested and excreted. The intake of 90Sr and 89Sr with airborne particles was 0.6–1.7 and 3–14 pc/day, respectively. The volume of air inhaled daily was computed from this intake to be 11 ± 4 m3.

The variation in the average dose from an internally deposited radionuclide with the radionuclide, its chemical form and route of administration is fairly well known. Maximum permissible dose levels are normally based upon the administration of a given quantity of radionuclide to “standard man”, a hypothetical adult of average weight and height, as well as chemical composition. This study considers dose levels for infants and children. A series of standard children of various ages was derived by supplementing values of the fiftieth percentile for heights and weights of certain ages with pertinent information on organ weights and physiology. Age groups selected for this study include: newborn, 1, 5, 10 and 15 years old. Average absorption doses in mrad/μc administered were then calculated for the whole body and/or critical organ using the general beta and gamma dose formulae. The average whole body doses ranged from 10 to 20 times greater in the newborn than standard man for a given quantity of administered radioactivity. Furthermore, since infants and children breathe more air on a per weight basis than an adult and since their water intake is also greater on a per weight basis, maximum permissible concentration guides based upon standard man do not apply to younger individuals.

Review: 128 refs.

Isolated cases of pneumothorax or pneumomediastinum have been reported following therapeutic pneumoperitoneum (Stein, 1951) and of course diagnostic pneumoperitoneum may be used to prove a suspected defect in the diaphragm, but the following is believed to be the first case reported of pneumothorax complicating pelvic pneumography.A 36-year-old woman was referred for pelvic pneumography because of pelvic pain and suspicion of a right adnexal mass.