| 1. |
- Ion, John, et al.
(författare)
-
Laser surface modification of a 13.5% Cr, 0.6% C steel
- 1991
-
Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 26:1, s. 43-48
-
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.
|
|
| 2. |
- Borrow, Julian, et al.
(författare)
-
Diagnosis of acute promyelocytic leukaemia by RT-PCR: detection of PML-RARA and RARA-PML fusion transcripts
- 1992
-
Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 82:3, s. 529-540
-
Tidskriftsartikel (refereegranskat)abstract
- Acute promyelocytic leukaemia (APL; AML M3) is identified by a unique t(15;17) translocation which fuses the PML gene to the retinoic acid receptor alpha gene (RARA). Reverse transcription coupled with the polymerase chain reaction (RT-PCR) has been used to develop a diagnostic test for APL based on the PML-RARA fusion message. Separate PCR assays were designed to amplify either PML-RARA (15q+ derived) or RARA-PML (17q- derived) chimaeric transcripts. PML-RARA transcripts were detected in every case from a series of 18 APL patients with cytogenetically confirmed t(15;17) translocations, whereas RARA-PML messages were detected in only 67% (12/18) of these patients. This suggests that it is the 15q+ derivative which mediates leukaemogenesis. Furthermore the PCR approach (or Southern analysis) may be used to identify in which of the alternative PML introns the breakpoint occurs; 52% of cases (15/29 patients) utilize a 5' PML intron and 48% the 3' intron (14/29 cases). Neither the choice of PML intron nor the expression of the 17q- derivative could be correlated with the microgranular variant of APL (M3V), overall survival rate, age, sex or presence of coagulopathy. Finally, the fusion message is undetectable in five remission samples. This indicates a possible use for RT-PCR in monitoring remission patients for evidence of relapse.
|
|
| 3. |
- Chen, F., et al.
(författare)
-
Evaluation of a workstation for letter sorting in the Beijing post office
- 1993
-
Ingår i: Occupational and environmental economics. - : Indian Society of Ergonomics.. - 819005080X ; , s. 61-66
-
Konferensbidrag (refereegranskat)abstract
- In the Chinese postal system, letters are sorted manually using a sorting frame, consisting of vertical and horizontal arrays of pigeon-holes of different dimensions. Letter sorting is a time consuming and a mentally intensive task involving repetitive movements of shoulder and hand muscles. Musculoskeletal complaints and disorders of the lower back, shoulder and hand occur frequently among the letter sorting workers. A total of 293 letter-sorters (71 males and 222 females) from Beijing Postal Sorting Office were subjected to a general health check-up including musculoskeletal disorders coupled with administration of a questionnaire. The worker's daily work load was evaluated by counting the number of letters sorted in each pigeon-hole in the sorting frame and also by considering their arm movements and body postures. The workplace dimensions were also measured. Results revealed that 62.1% of the workers complained of low back pain, 78.5% of shoulder pain and 48.8% of hand pain. A high percentage of workers seemed to have mental intensive symptoms, such as, headache, dizziness and drowsiness. Almost 25% of the female wokers indicated irregularity in their menstruation. An improved ergonomic design of the sorting frame is recommended.
|
|
| 4. |
|
|
| 5. |
- Ion, John, et al.
(författare)
-
Laser transformation hardening of low alloy hypoeutectoid steel
- 1992
-
Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 8:9, s. 799-804
-
Tidskriftsartikel (refereegranskat)abstract
- The principles of laser transformation hardening were investigated using a low alloy special steel having a microstructure of pearlite and proeutectoid ferrite. Temperature fields and phase transformations were modelled. Particular attention was paid to increases of the Ac1 and Ac3 transformation temperatures owing to the rapid thermal cycles produced by laser heating. Dissolution of proeutectoid ferrite is shown to control the formation of a homogeneous hardened case. Experimental data are in good agreement with the predictions of the model. A diagram was constructed which describes the case geometry and microstructure in terms of the process variables and is an aid to optimising practical processing parameters. The models are flexible and may be used for laser transformation hardening of other ferrous alloys having inhomogeneous microstructures.
|
|
| 6. |
- Steenfos, H, et al.
(författare)
-
Increased gene expression of scatter factor-hepatocyte growth factor and basic fibroblast growth factor in granulation tissue in the rat.
- 1993
-
Ingår i: Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society. - 1067-1927. ; 1:4, s. 231-5
-
Tidskriftsartikel (refereegranskat)abstract
- Scatter factor-hepatocyte growth factor is a protein secreted by fibroblasts which disperses colonies of epithelial cells and keratinocytes in culture. The factor is also a patent mitogen for hepatocytes, synthesized in the liver. Basic fibroblast growth factor, another heparin-binding factor, is most abundant in the brain but also plays a role in wound healing. Using a solution hybridization/RNAase protection assay, we have measured the abundance of messenger RNA for scatter factor-hepatocyte growth factor and basic fibroblast growth factor in granulation tissue obtained from subcutaneously Hunt-Schilling wound cylinders. The levels of scatter factor-hepatocyte growth factor messenger RNA increased after weeks 2 through 4 to a twofold higher level in weeks 5 through 7 after implantation of the cylinders, whereas no changes in basic fibroblast growth factor messenger RNA levels were noticed. At week 3 after implantation of the cylinders, scatter factor-hepatocyte growth factor messenger RNA levels in granulation tissue were more than threefold higher than in skin dermis fibroblasts but markedly lower than in the liver. The abundance of basic fibroblast growth factor messenger RNA was also significantly increased in granulation tissue compared with dermis but, as expected, markedly lower than in the brain. In conclusion, the gene expression of the scatter factor-hepatocyte growth factor, as well as basic fibroblast growth factor, is increased in granulation tissue. Because there was a time-dependent increase in the expression of scatter factor-hepatocyte growth factor, it is hypothesized that scatter factor-hepatocyte growth factor acts as a signal from fully developed granulation tissue to stimulate skin epithelial cells to scatter over the wound.
|
|
