Search PubMed⌕ Search

Biomedical subjects

S Marklund

Publications and source records attributed to S Marklund.

77 records · Page 5Linked to original sources
PubMedDate not supplied

Removal of dioxins and related aromatic hydrocarbons from flue gas streams by adsorption and catalytic destruction.

The dioxin removing capacity of the shell dedioxin system (SDDS-a Ti/V oxidative type catalyst) has been tested using the Umeå lab-scale incinerator over the temperature range 100-230 degrees C and at space velocities of 8000 and 40,000 h(-1). Other analogous organic compounds, such as PCBs, PAHs, chlorobenzenes and chlorophenols have also been investigated. Results show a high degree of dioxin removal already at 100 degrees C (82%), which occurs mainly by adsorption. When the temperature is raised a transition towards destruction is seen and at 150 degrees C, gas hour space velocity (GHSV) 8000 and at 230 degrees C, GHSV 40,000 virtually all removal is by destruction. High PCDD/F destruction efficiencies are reported (> 99.9%, based on I-TEQ); the other dioxin-related species and PAHs are also removed and destroyed to a significant extent. The SDDS has proved to be an effective means of destroying organic compounds in the gas phase, particularly dioxins, at temperatures as low as 150 degrees C.

Journal Article↗
PubMedDate not supplied

Effects of oxygen on formation of PCB and PCDD/F on extracted fly ash in the presence of carbon and cupric salt.

The effect of oxygen-nitrogen atmosphere (N2 + 10%O2, N2 + 1%O2 and 99.999% N2) on the formation of PCB, PCDD and PCDF by the de novo synthetic reactions in the system consisting of extracted fly ash (from municipal waste incinerators--MWI), activated carbon, CuCl2 x 2H2O and NaCl at 340 degrees C was studied. The content of PCDD/F for systems with 10%O2, 1%O2 and 99.999% N2 was decreasing and corresponded to 17,304, 5544, and 1437 ng/sample. In all studied systems the isomer OCDD/F was prevailing. The content of PCBs in the same system was also decreasing from 1214 to 166 ng/g. Formation of nonortho PCB was relatively high compared to the system where only nitrogen was present. The possible mechanism of formation is outlined.

Air Pollution↗
PubMedDate not supplied

An intraindividual clinical comparison of 2 metal-ceramic systems.

PURPOSE: It has been questioned whether the surface and color of the ceramic and the metal-ceramic bond strength of a titanium-ceramic system are comparable to those of a conventional noble alloy-ceramic system. It was therefore the aim of this study to carry out an intraindividual clinical comparison between crowns fabricated according to the Procera system (titanium copings veneered with a low-fusing ceramic) and noble-alloy copings veneered with a medium-fusing ceramic. MATERIALS AND METHODS: Twenty-one crown pairs were fabricated for eighteen patients; three of the patients were each provided with two crown pairs. After 2 years nineteen crown pairs in sixteen patients could be compared. Clinical examinations were performed by two calibrated dentists who are long experienced in prosthetic dentistry. The crowns were rated according to the California Dental Association system. In addition, Bleeding Index and Margin Index were evaluated. RESULTS: After 2 years the quality of surface and color of the ceramic material seemed to have deteriorated more in titanium-ceramic crowns than in conventional metal-ceramic crowns, although the difference was not statistically significant. Regarding anatomic form, margin integrity, Bleeding Index, and Margin Index the differences between the two crown systems were small. CONCLUSION: The low-fusing ceramics have been subject to improvements during the last few years. Their bond strength to titanium seems to be comparable to that of conventional metal-ceramic systems. However, in the long run one problem may be the surface and color stability of low-fusing ceramics. To make extended long-term comparisons between the two metal-ceramic systems possible the present patient material will be followed for a longer period than the current 2 years.

Adult↗