The Experts below are selected from a list of 600705 Experts worldwide ranked by ideXlab platform
M Alaopas - One of the best experts on this subject based on the ideXlab platform.
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mr urography in evaluation of acute flank pain
American Journal of Roentgenology, 2012Co-Authors: M Sudah, Ritva Vanninen, Kaarina Partanen, A Heino, Petri Vainio, M AlaopasAbstract:OBJECTIVE. The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain.SUBJECTS AND METHODS. Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference.RESULTS. Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the det...
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mr urography in evaluation of acute flank pain t2 weighted sequences and gadolinium enhanced three dimensional flash compared with urography fast low angle shot
American Journal of Roentgenology, 2001Co-Authors: M Sudah, Ritva Vanninen, Kaarina Partanen, A Heino, Petri Vainio, M AlaopasAbstract:OBJECTIVE. The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain.SUBJECTS AND METHODS. Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference.RESULTS. Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the det...
R H Müller - One of the best experts on this subject based on the ideXlab platform.
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Characterization of nebulized buparvaquone nanosuspensions - effect of nebulization technology
2005Co-Authors: Hernandez-trejo N, Kayser O, Steckel H, R H MüllerAbstract:The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis carinii pneumonia (PCP) lung infections. Physically stable nanosuspensions were formulated in order to deliver the drug at the site of infection using nebulization. The aerosolization characteristics of two buparvaquone nanosuspensions were determined with commercial jet and ultrasonic nebulizer devices. Aerosol droplet size distribution was determined with laser diffractometry (LD). Nebulization of the nanosuspensions and dispersion media surfactant solutions produced aerosol droplets diameters in the range from 3 to 5 mu m for Respi-jet Kendall, Pari Turbo Boy system and Multisonic nebulizers and particles around 9-10 mm with Omron U1. Fractions of the nanosuspensions from the nebulizer reservoir and of aerosol produced were collected to investigate changes in the size of the drug nanocrystals influenced by the nebulization technology. Comparisons were performed measuring the drug nanocrystals with photon correlation spectroscopy (PCS) and LD of the samples. Drug particle aggregates were detected in the fractions of aerosol collected from jet nebulizers. Nebulizer technology ( jet vs. ultrasonic) showed influence on the stability of the drug particle size distribution of buparvaquone nanocrystals during the nebulization time evaluated
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characterization of nebulized buparvaquone nanosuspensions effect of nebulization technology
Journal of Drug Targeting, 2005Co-Authors: Norma Hernandeztrejo, Hartwig Steckel, Oliver Kayser, R H MüllerAbstract:The poorly soluble drug buparvaquone is proposed as an alternative treatment of Pneumocystis carinii pneumonia (PCP) lung infections. Physically stable nanosuspensions were formulated in order to deliver the drug at the site of infection using nebulization. The aerosolization characteristics of two buparvaquone nanosuspensions were determined with commercial jet and ultrasonic nebulizer devices. Aerosol droplet size distribution was determined with laser diffractometry (LD). Nebulization of the nanosuspensions and dispersion media surfactant solutions produced aerosol droplets diameters in the range from 3 to 5 μm for Respi-jet Kendall, Pari Turbo Boy system and Multisonic nebulizers and particles around 9–10 μm with Omron U1. Fractions of the nanosuspensions from the nebulizer reservoir and of aerosol produced were collected to investigate changes in the size of the drug nanocrystals influenced by the nebulization technology. Comparisons were performed measuring the drug nanocrystals with photon correlat...
Bengt Johansson - One of the best experts on this subject based on the ideXlab platform.
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investigation of performance and emission characteristics of a heavy duty natural gas engine operated with pre chamber spark plug and dilution with excess air and egr
SAE International journal of engines, 2012Co-Authors: Ashish Shah, Per Tunestal, Bengt JohanssonAbstract:This article deals with application of turbulent jet ignition technique to heavy duty multi-cylinder natural gas engine for mobile application. Pre-chamber spark plugs are identified as a promising means of achieving turbulent jet ignition as they require minimal engine modification with respect to component packaging in cylinder head and the ignition system. Detailed experiments were performed with a 6 cylinder 9.4 liter turbo-charged engine equipped with multi-point gas injection system to compare performance and emissions characteristics of operation with pre-chamber and conventional spark plug. The results indicate that ignition capability is significantly enhanced as flame development angle and combustion duration are reduced by upto 30 % compared to those with conventional spark plugs at certain operating points. Maximum possible dilution (limited by combustion stability index, Coefficient of Variation (COV) of Gross Indicated Mean Effective Pressure (IMEPg)) with excess air and EGR were investigated experimentally at engine speed of 1500 rpm and 5, 12 and 18 bar IMEPg operating load and results indicate that the lean limit is extended by 0.8-1 Lambda unit and 5-8% EGR rate units. It was also observed that pre-chamber spark plugs cause charge pre-ignition at loads exceeding 10-12 bar IMEPg. To avoid this, the minimum amount of dilution, with excess air and then EGR, which is required to operate above 10 bar IMEPg was estimated experimentally. Finally, to compare performance and emission characteristics of operation with these two ignition techniques, the engine was tested on an ESC-like (European Stationary Cycle) 12 mode cycle. Results indicated marginal reduction in cycle averaged NOx emissions with maximum excess air dilution and about 50% reduction with maximum EGR dilution, whereas CO and HC emissions increased. Other operating characteristics like the flame development angle, combustion duration, brake efficiency etc. are also compared for the tested operating range of the test engine. (Less)
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applicability of ionization current sensing technique with plasma jet ignition using prechamber spark plug in a heavy duty natural gas engine
SAE 2012 International Powertrains Fuels & Lubricants Meeting, 2012Co-Authors: Ashish Shah, Per Tunestal, Bengt JohanssonAbstract:This article deals with study of ionization current sensing technique's signal characteristics while operating with pre-chamber spark plug to achieve plasma jet ignition in a 6 cylinder 9 liter turbo-charged natural gas engine under EGR and excess air dilution. Unlike the signal with conventional spark plug which can be divided into distinct chemical and thermal ionization peaks, the signal with pre-chamber spark plug shows a much larger first peak and a negligible second peak thereafter. Many studies in past have found the time of second peak coinciding with the time of maximum cylinder pressure and this correlation has been used as an input to combustion control systems but the absence of second peak makes application of this concept difficult with pre-chamber spark plug. However, it has been observed that the first peak is very strong and does not deteriorate much even under lean operation and hence ion current signal integral can be used to calculate real time combustion stability parameters for combustion control systems. The correlation between the coefficient of variation (COV) of indicated mean effective pressure (IMEP) and ion current integral for operation at 5, 12 and 18 bar IMEP load under stoichiometric and diluted operation with EGR and excess air is presented in this article. (Less)
M Sudah - One of the best experts on this subject based on the ideXlab platform.
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mr urography in evaluation of acute flank pain
American Journal of Roentgenology, 2012Co-Authors: M Sudah, Ritva Vanninen, Kaarina Partanen, A Heino, Petri Vainio, M AlaopasAbstract:OBJECTIVE. The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain.SUBJECTS AND METHODS. Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference.RESULTS. Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the det...
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mr urography in evaluation of acute flank pain t2 weighted sequences and gadolinium enhanced three dimensional flash compared with urography fast low angle shot
American Journal of Roentgenology, 2001Co-Authors: M Sudah, Ritva Vanninen, Kaarina Partanen, A Heino, Petri Vainio, M AlaopasAbstract:OBJECTIVE. The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain.SUBJECTS AND METHODS. Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference.RESULTS. Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the det...
Ashish Shah - One of the best experts on this subject based on the ideXlab platform.
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investigation of performance and emission characteristics of a heavy duty natural gas engine operated with pre chamber spark plug and dilution with excess air and egr
SAE International journal of engines, 2012Co-Authors: Ashish Shah, Per Tunestal, Bengt JohanssonAbstract:This article deals with application of turbulent jet ignition technique to heavy duty multi-cylinder natural gas engine for mobile application. Pre-chamber spark plugs are identified as a promising means of achieving turbulent jet ignition as they require minimal engine modification with respect to component packaging in cylinder head and the ignition system. Detailed experiments were performed with a 6 cylinder 9.4 liter turbo-charged engine equipped with multi-point gas injection system to compare performance and emissions characteristics of operation with pre-chamber and conventional spark plug. The results indicate that ignition capability is significantly enhanced as flame development angle and combustion duration are reduced by upto 30 % compared to those with conventional spark plugs at certain operating points. Maximum possible dilution (limited by combustion stability index, Coefficient of Variation (COV) of Gross Indicated Mean Effective Pressure (IMEPg)) with excess air and EGR were investigated experimentally at engine speed of 1500 rpm and 5, 12 and 18 bar IMEPg operating load and results indicate that the lean limit is extended by 0.8-1 Lambda unit and 5-8% EGR rate units. It was also observed that pre-chamber spark plugs cause charge pre-ignition at loads exceeding 10-12 bar IMEPg. To avoid this, the minimum amount of dilution, with excess air and then EGR, which is required to operate above 10 bar IMEPg was estimated experimentally. Finally, to compare performance and emission characteristics of operation with these two ignition techniques, the engine was tested on an ESC-like (European Stationary Cycle) 12 mode cycle. Results indicated marginal reduction in cycle averaged NOx emissions with maximum excess air dilution and about 50% reduction with maximum EGR dilution, whereas CO and HC emissions increased. Other operating characteristics like the flame development angle, combustion duration, brake efficiency etc. are also compared for the tested operating range of the test engine. (Less)
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applicability of ionization current sensing technique with plasma jet ignition using prechamber spark plug in a heavy duty natural gas engine
SAE 2012 International Powertrains Fuels & Lubricants Meeting, 2012Co-Authors: Ashish Shah, Per Tunestal, Bengt JohanssonAbstract:This article deals with study of ionization current sensing technique's signal characteristics while operating with pre-chamber spark plug to achieve plasma jet ignition in a 6 cylinder 9 liter turbo-charged natural gas engine under EGR and excess air dilution. Unlike the signal with conventional spark plug which can be divided into distinct chemical and thermal ionization peaks, the signal with pre-chamber spark plug shows a much larger first peak and a negligible second peak thereafter. Many studies in past have found the time of second peak coinciding with the time of maximum cylinder pressure and this correlation has been used as an input to combustion control systems but the absence of second peak makes application of this concept difficult with pre-chamber spark plug. However, it has been observed that the first peak is very strong and does not deteriorate much even under lean operation and hence ion current signal integral can be used to calculate real time combustion stability parameters for combustion control systems. The correlation between the coefficient of variation (COV) of indicated mean effective pressure (IMEP) and ion current integral for operation at 5, 12 and 18 bar IMEP load under stoichiometric and diluted operation with EGR and excess air is presented in this article. (Less)
