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- Lekholm, Ville, 1976-, et al.
(författare)
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Investigation of a zirconia co-fired ceramic calorimetric microsensor for high-temperature flow measurements
- 2015
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 25:6
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the design, fabrication and characterization of a flow sensor for high-temperature, or otherwise aggressive, environments, like, e.g. the propulsion system of a small spacecraft. The sensor was fabricated using 8 mol% yttria stabilized zirconia (YSZ8) high-temperature co-fired ceramic (HTCC) tape and screen printed platinum paste. A calorimetric flow sensor design was used, with five 80 mu m wide conductors, separated by 160 mu m, in a 0.4 mm wide, 0.1 mm deep and 12.5 mm long flow channel. The central conductor was used as a heater for the sensor, and the two adjacent conductors were used to resistively measure the heat transferred from the heater by forced convection. The two outermost conductors were used to study the influence of an auxiliary heat source on the sensor. The resistances of the sensor conductors were measured using four-point connections, as the gas flow rate was slowly increased from 0 to 40 sccm, with different power supplied through the central heater, as well as with an upstream or downstream heater powered. In this study, the thermal and electrical integrability of microcomponents on the YSZ8 substrate was of particular interest and, hence, the influence of thermal and ionic conduction in the substrate was studied in detail. The effect of the ion conductivity of YSZ8 was studied by measuring the resistance of a platinum conductor and the resistance between two adjacent conductors on YSZ8, in a furnace at temperatures from 20 to 930 degrees C and by measuring the resistance with increasing current through a conductor. With this design, the influence of ion conductivity through the substrate became apparent above 700 degrees C. The sensitivity of the sensor was up to 1 m Omega sccm(-1) in a range of 0-10 sccm. The results show that the signal from the sensor is influenced by the integrated auxiliary heating conductors and that these auxiliary heaters provide a way to balance disturbing heat sources, e.g. thrusters or other electronics, in conjunction with the flow sensor.
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| 2. |
- Thornell, Anders, 1976
(författare)
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Laparoscopic Lavage - A Paradigm Shift for the Treatment of Perforated Diverticulitis with Purulent Peritonitis?
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Perforated diverticulitis of the colon is a condition that sometimes requires surgical treatment. Traditionally Hartmann’s procedure is the recommended treatment. Laparoscopic lavage has lately evoked interest as a definite treatment for perforated diverticulitis with purulent peritonitis. Aim: To evaluate the surgical treatment for perforated diverticulitis and to assess laparoscopic lavage as a definite treatment for perforated diverticulitis with purulent peritonitis. Patients and Methods: Paper I explores the morbidity and mortality of patients operated due to perforated diverticulitis at Sahlgrenska University Hospital 2003 to 2008. Papers II-IV describe the conception, structure and the results of the randomised controlled trial DILALA, which compares laparoscopic lavage to Hartmann’s procedure as a treatment for perforated diverticulitis with purulent peritonitis. Results: Paper I found that 44% of the patients were re-operated after surgical treatment for perforated diverticulitis. The mortality rate during first admission was 6%. The stoma, a result from Hartmann’s procedure, became permanent in 40% of the patients. The DILALA-trial showed that for laparoscopic lavage 28% were re-operated compared to 63% for the Hartmann’s procedure, a relative risk reduction of 59% for re-operation (RR 0.41, 95% CI 0.23-0.72) (p=0.004) There was also significantly shorter operating time and shorter length of hospital stay. No differences were found in mortality, morbidity or quality of life. Conclusion: The scientific evidence for laparoscopic lavage is still limited but our results indicate that laparoscopic lavage is superior to Hartmann’s procedure when treating perforated diverticulitis with purulent peritonitis.
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