| 1. |
- Pettersson, Gunilla, et al.
(författare)
-
Upgrading the strength properties of sheets from hardwood high yield pulps
- 2018
-
Ingår i: Pan Pacific Fibre Value Chain Conference 2018, Proceedings. - : Appita Inc.. - 9780975746998 ; , s. 142-147
-
Konferensbidrag (refereegranskat)abstract
- In the current paper it is shown that tensile and compression strength of sheets from hardwood high yield pulps (HYP), which has been manufactured at a low energy input in refining, can be multiplied by improving the fibre-fibre bond strength and the number of contact areas between fibre surfaces in the sheet structure. At fibre surface treatment with cationic starch the properties are improved at almost preserved bulk (i.e., preserved density). Remarkable improvements are achieved at densification of the sheet structures by pressing in a hot press nip at temperatures well above the softening temperature of wet lignin. The former technique is above all to prefer in manufacturing of middle plies in paperboard composites, whereas the latter technique is of special interest in manufacturing of packaging papers with high demands upon strength. For instance, it is shown in the paper how tensile index on sheets of CTMP from birch (CSF 480 ml) can be enhanced from 20 to 50 kNm/kg and compression index (SCT) from 10 to 35 kNm/kg by the tested techniques.
|
|
| 2. |
- Sundbom, Per, et al.
(författare)
-
Sound analysis of a left ventricular assist device: A technical evaluation of iOS devices
- 2018
-
Ingår i: International Journal of Artificial Organs. - : SAGE PUBLICATIONS LTD. - 0391-3988 .- 1724-6040. ; 41:5, s. 254-260
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: The use of left ventricular assist device (LVAD) has grown rapidly. Adverse events do continue to occur. In recent years, analysis of LVAD sound recordings emerged as a means to monitor pump function and detect pump thrombosis. The aim of this study was to characterize the sounds from HeartMate II and to evaluate the use of handheld iOS devices for sound recordings. Method: Signal analysis of LVAD sound recordings, with dedicated recording equipment and iOS devices, was performed. Two LVADs running in mock loop circuits were compared to an implanted LVAD. Spectral analysis and parametric signal models were explored to quantify the sound and potentially detect changes in it. Results: The sound recordings of two LVADs in individual mock loop circuits and a third one implanted in a patient appeared to be similar. Qualitatively, sound characteristics were preserved following changes in pump speed. Recordings using dedicated equipment showed that HeartMate II sound comprises low-frequency components corresponding to pump impeller rotation, as well as high-frequency components due to a pulse width modulation of the electric power to the pump. These different signal components interact and result in a complicated frequency spectrum. The iPhone and iPod recordings could not reproduce the sounds as well as the dedicated equipment. In particular, lower frequencies were affected by outside disturbances. Discussion: This article outlines a systematic approach to LVAD sound analysis using signal processing methods to quantify and potentially detect changes, and describes some of the challenges, for example, with the use of inexpensive recording devices.
|
|
| 3. |
- Sundbom, Per, 1981-, et al.
(författare)
-
Sound analysis of the magnetically levitated left ventricular assist device HeartMate 3™
- 2019
-
Ingår i: International Journal of Artificial Organs. - : Sagamore Publishing. - 0391-3988 .- 1724-6040. ; 42:12, s. 717-724
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The HeartMate 3™ has shown lower rates of adverse events compared to previous devices due to the design and absence of mechanical bearings. For previous devices, sound analysis emerged as a way to assess pump function. The aims of this study were to determine if sound analysis can be applied to the HeartMate 3 in vivo and in vitro and to evaluate an electronic stethoscope.METHOD: Sound recordings were performed with microphones and clinical accessible electronic stethoscope. The recordings were studied in both the time and the frequency domains. Recordings from four patients were performed to determine if in vivo and in vitro recordings are comparable.RESULTS: The results show that it is possible to detect sound from HeartMate 3 and the sound spectrum is clear. Pump frequency and frequency of the pulsatile mode are easily determined. Frequency spectra from in vitro and in vivo recordings have the same pattern, and the major proportion (96.7%) of signal power is located at the pump speed frequency ±40 Hz. The recordings from the patients show low inter-individual differences except from location of peaks originating from pump speed and harmonics. Electronic stethoscopes could be used for sound recordings, but the dedicated equipment showed a clearer sound spectrum.DISCUSSION: The results show that acoustic analysis can also be performed with the HeartMate 3 and that in vivo and in vitro sound spectrum is similar. The frequency spectra are different from previous devices, and methods for assessing pump function or thrombosis need further evaluation.
|
|
| 4. |
- Vikholm, Per, 1985-, et al.
(författare)
-
Validity of the Swedish Cardiac Surgery Registry
- 2018
-
Ingår i: Interactive Cardiovascular and Thoracic Surgery. - : OXFORD UNIV PRESS. - 1569-9293 .- 1569-9285. ; 27:1, s. 67-74
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Our goal was to validate the Swedish Cardiac Surgery Registry by reviewing the reported cardiac operations to assess the completeness and quality of the registered data and the EuroSCORE II variables. METHODS: A total of 5837 cardiac operations were reported to the Swedish Cardiac Surgery Registry in Sweden during 2015. A randomly selected sample of 753 patient records (13%) was scrutinized by 3 surgeons at all 8 units in Sweden performing open cardiac surgery in adults. RESULTS: Coverage was excellent with 99% [95% confidence interval (CI) 98-99%] of the performed procedures found in the registry. Reported waiting times for surgery were correct in 78% (95% CI 76-79%) of the cases. The main procedural code was correctly reported in 96% (95% CI 95-97%) of the cases. The correlation between reported and monitored logistic EuroSCORE II had a coefficient of 0.79 (95% CI 0.76-0.82), and the median difference in EuroSCORE II was 0% (interquartile range -0.4% to 0.4%). The majority of EuroSCORE II variables had good agreement and coherence; however, New York Heart Association functional class, preoperative renal dysfunction, left ventricular ejection fraction, Canadian Cardiovascular Society Class IV angina and poor mobility were less robust Postoperative complications were rare and in general had a high degree of completeness and agreement. CONCLUSIONS: The reliability of the variables in the national Swedish Cardiac Surgery Registry was excellent. Thus, the registry is a valuable source of data for quality studies and research. Some EuroSCORE II variables require improved and stricter definitions to obtain uniform reporting and high validity.
|
|
