| 1. |
- Ion, John, et al.
(författare)
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Laser surface modification of a 13.5% Cr, 0.6% C steel
- 1991
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 26:1, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- A 13.5% Cr, 0.6% C steel, with an initial microstructure of chromium carbides in a ferrite matrix, was heat-treated by scanning a high-power laser beam over the surface. The aim was to compare the physical and chemical properties produced by this type of selective surface treatment with those resulting from a conventional furnace desensitization and quench-hardening heat treatment. Surface heating homogenized the carbon originally bound in the carbides sufficiently to produce martensite, giving hardening to levels comparable with a conventional heat treatment. Chromium-rich zones, carbides and retained austenite were also detected in the heated microstructure. Surface melting produced complete homogenization of both carbon and chromium, which resulted in the retention of large amounts of austenite in the microstructure on cooling to room temperature. Subsequent refrigeration at - 196 °C transformed some of the austenite to martensite. Pitting corrosion and local reductions in hardness were observed adjacent to treated areas under certain conditions, due to precipitation of secondary carbides and elevated tempering, respectively.
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| 2. |
- Wieslander, Anders P, et al.
(författare)
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In vitro toxicity of biomaterials determined with cell density, total protein, cell cycle distribution and adenine nucleotides
- 1993
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Ingår i: Artificial Cells, Blood Substitutes, and Biotechnology. - : Informa UK Limited. - 1055-7172. ; 21:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Inhibition of cell growth is the most commonly used endpoint for in vitro toxicity of biomaterials. The use of several different endpoints might however generate more information concerning the nature of the toxicity. Thus, we examined the toxicity of two biomaterials, Polyvinylchloride (PVC) and Polyoximethene (POM), with different selected endpoints. The influence of cell growth on these endpoints was also investigated. Water extracts from the polymeric materials were tested on the continuous cell line L-929. Cell density, total protein, total protein per cell, fraction of cells in G0/G1- or S-phase, the concentration of ATP, ADP and AMP were used as endpoints. The PVC material did not significantly influence any of these endpoints until after 72 hours of exposure and the main part of the toxicity at 72 hours was related to higher proliferation rate in control cultures. After the cells had been incubated for 8 hour with POM the main toxic effect was on the energy parameters. In conclusion the PVC material was less toxic than the POM material. Our results also implies that the choice of endpoint will influence the evaluation of cytotoxicity.
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| 3. |
- Baker, T. C., et al.
(författare)
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Identification and bioassay of sex pheromone components of carob moth, Ectomyelois ceratoniae (Zeller)
- 1991
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Ingår i: Journal of Chemical Ecology. - 0098-0331. ; 17:10, s. 1973-1988
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Tidskriftsartikel (refereegranskat)abstract
- Three sex pheromone components of the carob moth were isolated and identified from the extract of female pheromone glands, using a variety of techniques including coupled gas chromatographic-electroantennographic recordings, coupled gas chromatographic-mass spectrometric analysis, microozonolysis, electroantennographic assays of monounsaturated standards, wind-tunnel bioassays, and field trials. The major component was identified as (Z,E)-9,11,13-tetradecatrienal, a novel lepidopterous pheromone component structure. Two minor components, either one of which improves the upwind flight response of males when blended with the major component, were identified as (Z,E)-9,11-tetradecadienal, and (Z)-9-tetra-decenal.
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| 4. |
- Blomberg, L, et al.
(författare)
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Improved removal of anti-A and anti-B antibodies from plasma using blood-group-active haptens
- 1993
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Ingår i: Vox Sanguinis. - 1423-0410. ; 65:2, s. 126-135
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Tidskriftsartikel (refereegranskat)abstract
- Highly efficient anti-blood group A and B immunoadsorbents for extracorporeal treatment were developed by immobilizing A and B trisaccharide and A tetrasaccharide haptens on Sepharose 4FF and Fractogel TSK using three different methods. The adsorption of the IgG and IgM anti-A antibodies was essentially the same regardless of the A hapten used or the method of oligosaccharide coupling. The adsorption of IgM anti-A was found to be more sensitive than IgG anti-A to changes in column flow rate. The binding of both the IgM and IgG antibodies was slightly lower at 37 degrees C than at 22 degrees C. An anti-A/anti-B adsorbent column potentially suitable for treatment of patients was prepared. A column switching system resulted in a more efficient adsorption of antibodies. Hapten leakage from the column was very low. No nonspecific adsorption of plasma proteins to the column (other than traces of albumin) could be detected.
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| 5. |
- Dubiel, T W, et al.
(författare)
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Mitral valve prosthetic implantation with preservation of native mitral valve apparatus
- 1994
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Ingår i: Scandinavian journal of thoracic and cardiovascular surgery. - 0036-5580. ; 28:3-4, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- To avoid postoperative morbidity and mortality often associated with left ventricular dysfunction after mitral valve replacement (MVR) for chronic mitral insufficiency, reconstruction or preservation of the native mitral valve apparatus may be attempted during mitral prosthetic implantation (MPI). The effects of mitral surgery on heart function, studied with echocardiography and radionuclide angiography, were compared in seven patients with MPI (study group) and five with MVR (control group) who underwent complete preoperative, early postoperative and 3-6 months follow-up examinations. Preoperatively there was significant intergroup difference only in right ventricular ejection fraction measured at radionuclide angiography, which was lower in the MPI group (p < 0.05). At follow-up the MPI group had improved as regards this fraction (p < 0.005) and stroke volume index (p < 0.05). The number of patients with improved NYHA class at follow-up was significantly greater in the MPI group. Our preliminary experience with preservation of the native mitral valve apparatus thus suggests that the method offers haemodynamic advantages for postoperative right ventricular function.
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| 6. |
- Hansson, T
(författare)
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Fuktsäkert trä-syll-system
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syllen är den byggnadsdel av trä som utsätts för den största risken att bli fuktig under byggnadstiden. Risken kan minskas med byggnadstekniska insatser och val av lämpliga produktionsmetoder, torrt byggande. Ett antal behandlingar av trä har studerats med olika laboratoriemetoder. Rekommendationer ges till lämpliga åtgärder att vidta för att åstadkomma ett fuktsäkert träsyllsystem.
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| 7. |
- Hansson, T., et al.
(författare)
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High temperature fracture of a SiC whisker-reinforced alumina in air and vacuum
- 1994
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 13:5, s. 427-436
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Tidskriftsartikel (refereegranskat)abstract
- The fracture behaviour of a SiCw/alumina composite was studied between room temperature and 1320°C in vacuum by four-point bend testing of specimens pre-cracked by bridge indentation. The results are compared to those of earlier work on a similar material in air. In vacuum, the composite begins to exhibit stable crack growth (SCG) and increasing apparent toughness at about 1100°C. Between 1100 and 1320°C, the extent of SCG increases and the toughness rises to almost three times the room temperature fracture toughness. The toughness enhancement is due mainly to such processes as crack deflection, crack branching, microcrack zone formation and crack tip blunting rather than any temperature-related increase in intrinsic fracture resistance of the material. In air, the fracture processes are similar to those in vacuum but the toughness increase is delayed by about 100°C and the level of toughening is lower. These differences arise from the formation of a glass phase in air which delays microcrack formation but reduces the resistance to stable crack growth.
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| 8. |
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| 9. |
- Risberg, B, et al.
(författare)
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Inter-institutional reproducibility of flow cytometric DNA-analysis in breast carcinomas
- 1994
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Ingår i: Analytical Cellular Pathology. - 0921-8912. ; 6:1, s. 23-36
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Tidskriftsartikel (refereegranskat)abstract
- In order to study interinstitutional reproducibility of flow cytometric DNA-analysis (DNA-FCM), frozen pieces from 30 consecutive breast carcinomas were analysed by 5 laboratories. Different instruments, preparation and DNA staining methods were used. A concordance in DNA-ploidy status was obtained in 26 of the 30 tumours. The discrepancy can mainly be explained by intratumoural DNA-heterogeneity since a complete agreement in ploidy status was obtained when four of the laboratories analysed the same cell suspension, where solid bits showed differing results. The sampling method seems therefore to be a crucial step for the results and needs further studies. As far as the estimation of S-phase fraction was concerned, one laboratory obtained significantly higher values compared to the other four. The correlation between the other four laboratories varied between r = 0.66-0.92.
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| 10. |
- Shimizu, T, et al.
(författare)
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Inhibitory effects of theophylline, terbutaline, and hydrocortisone on leukotriene B4 and C4 generation by human leukocytes in vitro.
- 1994
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Ingår i: Pediatric pulmonology. - 8755-6863. ; 18:3, s. 129-34
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Tidskriftsartikel (refereegranskat)abstract
- Leukotriene B4 (LTB4) and leukotriene C4 (LTC4) are considered to be important mediators in the pathophysiology of asthma. Theophylline, terbutaline, and hydrocortisone are drugs commonly used in the treatment of asthma. In the present study we have investigated the in vitro inhibitory effects of theophylline, terbutaline, and hydrocortisone on LTB4 and LTC4 generation from human leukocytes. After preincubation in the presence of these drugs, the cells were stimulated with the calcium ionophore A 23187 and the supernatants were analyzed for their LTB4 and LTC4 content using reverse-phase high-performance liquid chromatography (HPLC). Total leukotriene (LT) production (the combined amounts of LTB4 and LTC4) was dose-dependently inhibited by pretreatment with theophylline, terbutaline or hydrocortisone. Therapeutic levels of hydrocortisone (5 x 10(-6) M) plus theophylline (5 x 10(-5) M) inhibited LTB4 and LTC4 production in an additive way, as did the combination of hydrocortisone plus terbutaline (5 x 10(-8) M). A statistically significant effect of diminished LTB4 generation was obtained after preincubation with therapeutic levels of theophylline plus terbutaline, but no such effect was seen for LTC4 levels. The in vitro inhibitory effects on LTB4 and LTC4 generation from human leukocytes by theophylline, terbutaline, and hydrocortisone, as well as the additive effect of hydrocortisone plus theophylline or terbutaline, add to our understanding of the therapeutic effects of these drugs in the treatment of bronchopulmonary obstruction.
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| 11. |
- Widell, Anders, et al.
(författare)
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Antibody to hepatitis-C-virus-related proteins in sera from alanine-aminotransferase-screened blood donors and prospectively studied recipients
- 1991
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Ingår i: Vox Sanguinis. - 1423-0410. ; 60:1, s. 28-33
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Tidskriftsartikel (refereegranskat)abstract
- A prospective study of posttransfusion non-A, non-B hepatitis was conducted in Malmo, Sweden, in 1984-1985, in which donors were alanine aminotransferase (ALT) screened but not ALT selected. Among 741 patients studied at 0, 6, and 12 weeks after transfusion, 13 developed non-A, non-B hepatitis, and these were further followed up. Stored sera from the 13 hepatitis patients and their 123 donors were tested for anti-hepatitis C virus (HCV) by ELISA and if positive, analyzed by recombinant immunoblot assay (RIBA). All ALT-elevated blood units (n = 301) and a similar number of ALT-normal units were also tested. Only 4/13 patients with non-A, non-B hepatitis seroconverted to anti-HCV, all with ALT peaks greater than 10 times the upper normal. All seroconversions occurred within 5 months after transfusion and could be confirmed by RIBA. Hepatitis C in recipients occurred both after transfusion of blood that was strongly positive, weakly positive, and/or negative for anti-HCV by ELISA. In donors grouped by ALT levels, the anti-HCV prevalence varied between 0.4 (normal ALT) and 14% (ALT elevated greater than or equal to 2 times). Of the total of 9 donor units positive by ELISA, only 5 were confirmed by RIBA. Of the 5 recipients of the RIBA-positive blood units, 3 went into hepatitis, 1 remained normal at 10.5 weeks, and 1 showed a slight, transient ALT elevation at week 12. The recipients of ELISA-positive but RIBA-negative blood remained healthy.
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