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- El-Ghoul, Zoel-Fikar, et al.
(författare)
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Wear analysis of pin and roller surfaces
- 2019
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Ingår i: 16th International Conference on Metrology and Properties of Engineering Surfaces (Met and Props 2017). - Bristol, UK : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- In this paper three different combinations were evaluated: (i) steel pin vs steel roller, (ii) steel pin vs tungsten disulfide (WS2) coated roller and (iii) PVD pin vs steel roller. The aim of this paper is to properly quantify the topographical variations of the pin/roller surfaces and asses the appropriateness of the measuring technique before and after the tribological tests primarily performed for friction reduction. In-house tribometer was used to test the friction/wear performance of the three different combinations. Surface topographies were measured by white light interferometer (3D) and mechanical stylus (2D). To enable fast relocation on the stylus and interferometer, a 3D printed mask was used. Regarding the pins, Sa, Sk and Svk have been found to follow the wear changes: the lowest wear change for the combination (ii) and highest for the combination (i) but less for the combination (iii). Regarding the changes of Ra on the pin locations where edge contact occurs, the largest changes were found to be for combination (i), followed by combination (ii) and (iii). Ra and Rk change less significantly for the roller surfaces. Good correlations among the friction, initial/final roughness and radial displacements were also found.
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| 2. |
- van den Berg, Johannes, et al.
(författare)
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Peripherally inserted central catheter in extremely preterm infants : Characteristics and influencing factors
- 2017
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Ingår i: Journal of Neonatal-Perinatal Medicine. - : IOS Press. - 1934-5798 .- 1878-4429. ; 10:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the duration of catheter stay, incidence of non-elective removal and rates of complications associated with peripherally inserted central catheters (PICCs) in relation to different catheter positions in extremely preterm infants (EPT, <28 weeks of gestation).METHODS: A retrospective analysis of Peripherally Inserted Central Catheters (PICCs) inserted in EPT infants over a 10-year period, from January 2004 through December 2013 (mean gestational age, 25.2 weeks; mean birth weight, 727g).RESULTS: Of the 379 PICCs analyzed, the majority of lines (68%) were placed in the central position, and 259 PICCs (56%) were removed electively after fulfilment of the treatment. Significantly more PICCs in the lower extremities compared to the upper extremities were in central positions (86% vs 61%, p<0.001, respectively). Significantly more PICCs that were removed electively after fulfilment of the treatment were in a central position compared to a non-central position (p<0.001). Of the 166 catheters that were removed because of complications, most (71%) of them had mechanical problems, and 13% had sepsis resulting in an incidence rate of 4.4/1000 catheter days.CONCLUSION: PICCs inserted in the lower extremity were more likely to have a centrally placed tip position compared to PICC lines inserted in the upper extremities.
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| 9. |
- Iftekhar, Shahriar, et al.
(författare)
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Phase formation of CaAl2O4 from CaCO3-Al2O3 powder mixtures
- 2008
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 28:4, s. 747-756
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Tidskriftsartikel (refereegranskat)abstract
- Calcium aluminate is the main constituent in calcium aluminate cements, used in a wide range of applications in construction and mining industries and recently also as biomedical implant. In applications that demand very precise reaction features, such as the biomedical ones, the phase purity is of very high importance. In this paper the formation of CaAl2O4 from CaCO3–Al2O3 powder mixtures has been studied, varying holding times between 1 and 40 h and temperatures between 1300 and 1500 °C. Phase formation was studied in samples both quenched from the holding temperatures and in samples slowly cooled. Samples were characterized by X-ray powder diffraction (XRPD), using Guinier-Hägg film data and the Rietveld method, and scanning (SEM) and transmission (TEM) electron microscopy. Samples for TEM with very high site accuracy were produced using focused ion beam microscopy. In addition to CA (CaAl2O4) the samples contained major amounts of CA2 (CaAl4O7), C12A7 (Ca12Al14O33) and minor amounts of un-reacted A (Al2O3). Trace amounts of C3A (Ca3Al2O6) were observed only for samples heated to 1500 °C. The amount of the Ca-rich phase C12A7 was found to decrease with time as it reacts with A and, to a less degree, CA2 to form CA. In agreement with previous studies the amount of CA2 formed decreases comparatively slowly with time. Its un-reactivity is due to that it is concentrated in isolated porous regions of sizes up to 100 μm. The formation of the Ca aluminates is found to be in response to local equilibriums within small inhomogeneous regions, with no specific phase acting as an intermediate phase. Samples quenched from 1500 °C were found to contain smaller amounts of poorly crystallized phases. A reaction between C and A takes place already at 900 °C, forming a meta-stable orthorhombic modification of CA. The orthorhombic unit cell with a = 8.732(2) Å, b = 8.078(2) Å, c = √3·a = 15.124(4) Å was verified by electron diffraction, revealing frequent twinning and disorder of the crystallites.
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| 10. |
- Lagerberg, Johan W., et al.
(författare)
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Evaluation of the quality of blood components obtained after automated separation of whole blood by a new multiunit processor
- 2013
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Ingår i: Transfusion. - : Wiley. - 0041-1132 .- 1537-2995. ; 53:8, s. 1798-1807
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Reveos system (Terumo BCT) is a fully automated device able to process four whole blood (WB) units simultaneously into a plasma unit, a red blood cell (RBC) unit, and an interim platelet (PLT) unit (IPU). Multiple IPUs can be pooled to form a transfusable PLT product. The aim of our study was to evaluate the quality of components made with the Reveos system from either fresh (2-8hr) or overnight-held WB. STUDY DESIGN AND METHODS: A prototype of the Reveos system was used to process WB. RBCs were resuspended in SAGM, leukoreduced, and assayed for in vitro quality variables during a 42-day storage period at 2 to 6 degrees C. Twenty-four-hour in vivo recovery was determined on Day42. Plasma was assayed for cellular contamination and activation variables. IPUs were pooled with SSP+ additive solution for in vitro quality assessments during a 7-day storage period at room temperature. RESULTS: Reveos-produced RBCs and plasma units met the predefined requirements. RBC recovery was superior to control units. On Day42, hemolysis was below 0.8% and in vivo recovery was above 75% for all RBCs. Cellular contamination was lower for Reveos-produced plasma. PLT yield was higher with overnight-stored WB. PLT quality was well maintained during storage with no significant differences between the two groups. Conclusion: Blood components prepared with the Reveos from fresh or overnight-held WB meet quality criteria without any relevant difference between the two groups. The Reveos system has the potential to increase efficacy and standardization of blood component preparation.
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