| 1. |
- Ericsson, Olle, et al.
(författare)
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Clinical validation of a novel automated cell-free DNA screening assay for trisomies 21, 13, and 18 in maternal plasma.
- 2019
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Ingår i: Prenatal diagnosis. - : Wiley. - 1097-0223 .- 0197-3851. ; 39:11, s. 1011-1015
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate clinical performance of a new automated cell-free (cf)DNA assay in maternal plasma screening for trisomies 21, 18, and 13, and to determine fetal sex.Maternal plasma samples from 1200 singleton pregnancies were analyzed with a new non-sequencing cfDNA method, which is based on imaging and counting specific chromosome targets. Reference outcomes were determined by either cytogenetic testing, of amniotic fluid or chorionic villi, or clinical examination of neonates.The samples examined included 158 fetal aneuploidies. Sensitivity was 100% (112/112) for trisomy 21, 89% (32/36) for trisomy 18, and 100% (10/10) for trisomy 13. The respective specificities were 100%, 99.5%, and 99.9%. There were five first pass failures (0.4%), all in unaffected pregnancies. Sex classification was performed on 979 of the samples and 99.6% (975/979) provided a concordant result.The new automated cfDNA assay has high sensitivity and specificity for trisomies 21, 18, and 13 and accurate classification of fetal sex, while maintaining a low failure rate. The study demonstrated that cfDNA testing can be simplified and automated to reduce cost and thereby enabling wider population-based screening.
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| 2. |
- Borggren, Jesper, et al.
(författare)
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Temperature imaging in low-pressure flames using diode laser two-line atomic fluorescence employing a novel indium seeding technique
- 2016
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 122:3
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Tidskriftsartikel (refereegranskat)abstract
- The use of diode lasers for spatially resolved temperature imaging is demonstrated in low-pressure premixed methane–air flames using two-line atomic fluorescence of seeded indium atoms. This work features the advantages of using compact diode lasers as the excitation sources with the benefits of two-dimensional planar imaging, which is normally only performed with high-power pulsed lasers. A versatile and reliable seeding technique with minimal impact on flame properties is used to introduce indium atoms into the combustion environment for a wide range of flame equivalence ratios. A spatial resolution of around 210 µm for this calibration-free thermometry technique is achieved for three equivalence ratios at a pressure of 50 mbar in a laminar flat flame.
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| 3. |
- Kiefer, Johannes, et al.
(författare)
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Gas-Phase and Combustion Diagnostics by Infrared Laser-Induced Grating Spectroscopy
- 2016
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Ingår i: Optics and Photonics for Energy and the Environment, E2 2016. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- Infrared laser-induced grating spectroscopy (IR-LIGS) is a powerful method for the detection of molecules in atmospheric and combustion chemistry by exploiting their strong and species-specific fundamental vibrations. This work discusses potentials and limitations of the method.
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| 4. |
- Kiefer, Johannes, et al.
(författare)
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Misalignment Effects in Laser-Induced Grating Experiments
- 2016
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 70:12, s. 2025-2028
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced grating spectroscopy (LIGS) is an experimental method in which two pulsed laser beams and a continuous-wave laser beam have to be superimposed under well-defined angles to generate a coherent signal beam. In this Note, the possible effects of different forms of misalignment are examined. This includes the overlap of the pump lasers as well as the influence of the probe laser alignment on the temporal profile of the signal.
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| 5. |
- Sahlberg, Anna Lena, et al.
(författare)
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Investigation of ro-vibrational spectra of small hydrocarbons at elevated temperatures using infrared degenerate four-wave mixing
- 2016
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486. ; 47:9, s. 1130-1139
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Tidskriftsartikel (refereegranskat)abstract
- The ro-vibrational spectra around 3 µm of four small hydrocarbons (C2H2, CH4, C2H6 and C2H4) at 296, 550 and 820 K have been investigated using infrared degenerate four-wave mixing (IR-DFWM). The spectra were recorded in gas flows of nitrogen with small admixtures of the hydrocarbons. A fused silica glass tube surrounded by an electric heating wire was used to heat the gas flows. The recorded IR-DFWM spectra are compared with simulations using the spectral information available in the HITRAN database, in order to identify spectral lines. The measurements demonstrate good signal to noise ratio and good sensitivity even at elevated temperatures. Several weak hot lines were detected that are not included in the current database. This paper demonstrates the potential of IR-DFWM for purposes of investigating spectral lines at elevated temperatures, which is often a challenging task with conventional absorption spectroscopy techniques. The possibility of applying IR-DFWM for combustion diagnostics of small hydrocarbons is discussed from the detection limits of the measurements and the potential water line interference. Because of the non-linear nature of the DFWM technique, it provides much higher contrast for strong lines of small molecules over backgrounds of high-density weak lines, which commonly exist in hot gas flows of thermochemical reactions.
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| 6. |
- Sahlberg, Anna Lena, et al.
(författare)
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Mid-infrared laser-induced thermal grating spectroscopy in flames
- 2017
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 36:3, s. 4515-4523
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, laser-induced thermal grating spectroscopy (LITGS) in the spectral range around 3. μm is demonstrated as a versatile diagnostic tool. This spectral region is of particular interest in combustion diagnostics as many relevant species such as hydrocarbons and water exhibit fundamental vibrational modes and hence can be probed with high sensitivity. Another benefit of the IR-LITGS is that it allows performing spectroscopy in the infrared combined with signal detection in the visible. Hence, the strong thermal radiation inherent in flames does not represent an interference. As the first step, we present the application of IR-LITGS to cold gas flows, where traces of ethylene and water vapor are detected. The time-resolved LITGS signals, which can be acquired in a single laser shot, are rich in information and allow deriving temperature and to some extend chemical composition. In the second step, the IR-LITGS technique is applied to ethylene/air flames stabilized on a flat flame burner. A proof-of-concept study is carried out, in which the temperature is determined in the burned region of flames with systematically varied equivalence ratio (0.72 < Φ <. 2.57). Moreover, in a highly sooty flame, LITGS signals were recorded as a function of height above the burner and allowed the determination of the temperature profile. The proposed IR-LITGS method has the potential for enabling single-shot measurements of several parameters at a time. Its applicability to sooty flame environments opens up new opportunities to study the complex formation of carbonaceous particles in flames.
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| 7. |
- Sahlberg, Anna-Lena, et al.
(författare)
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Mid-Infrared Polarization Spectroscopy Measurements of Species Concentrations and Temperature in a Low-Pressure Flame
- 2019
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 73:6, s. 653-664
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative measurements of CH4 mole fractions at different HAB in the flame were realized by a calibration measurement in a low pressure gas flow of N2 with a small admixture of known amount of CH4. A comprehensive study of the collision effects on the IRPS signal was performed in order to quantify the flame measurement. The concentration and temperature measurements were found to agree reasonably well with simulations using Chemkin. These measurements We demonstrate quantitative measurements of CH4 mole fractions in a low pressure fuel-rich premixed dimethyl ether/oxygen/argon flat flame (Φ =1.87, 37 mbar) using mid-infrared polarization spectroscopy (IRPS). Non-intrusive in situ detection of CH4, C2H2 and C2H6 in the flame was realized by probing the fundamental asymmetric C-H stretching vibration bands in the respective molecules in the spectral range 2970-3340 cm-1. The flame was stabilized on a McKenna-type porous plug burner hosted in a low pressure chamber. The temperature at different heights above the burner (HAB) was measured from the line ratio of temperature sensitive H2O spectral lines recorded using IRPS. prove the potential of IRPS as a sensitive, non-intrusive, in situ technique in low pressure flames.
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| 8. |
- Sahlberg, Anna Lena, et al.
(författare)
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Mid-infrared pumped laser-induced thermal grating spectroscopy for detection of acetylene in the visible spectral range
- 2016
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 70:6, s. 1034-1043
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Tidskriftsartikel (refereegranskat)abstract
- We present mid-infrared laser-induced thermal grating spectroscopy (IR-LITGS) using excitation radiation around 3 μm generated by a simple broadband optical parametric oscillator (OPO). Acetylene as a typical small hydrocarbon molecule is used as an example target species. A mid-infrared broadband OPO pumped by the fundamental output of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used to generate the pump beams, with pulse energies of 6-10 mJ depending on the wavelength. The line width of the OPO idler beam was ∼5 cm-1, which is large enough to cover up to six adjacent acetylene lines. The probe beam was the radiation of a 532 nm cw solid state laser with 190 mW output power. Signals were generated in atmospheric pressure gas flows of N2, air, CO2 and Ar with small admixtures of C2H2. A detection limit of less than 300 ppm was found for a point measurement of C2H2 diluted in N2. As expected, the oscillation frequency of the IR-LITGS signal was found to have a large dependency on the buffer gas, which allows determination of the speed of sound. Moreover, the results reveal a very strong collisional energy exchange between C2H2 and CO2 compared to the other gases. This manifests as significant local heating. In summary, the MIR-LITGS technique enables spectroscopy of fundamental vibrational transitions in the infrared via detection in the visible spectral range.
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| 9. |
- Sahlberg, Anna-Lena, et al.
(författare)
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Non-intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four-wave mixing
- 2015
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 1097-4555 .- 0377-0486. ; 46:8, s. 695-701
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the potential of infrared degenerate four-wave mixing (IR-DFWM) as a tool for non-intrusive in situ spatially resolved detection of CH3Cl in reactive hot gas flows especially feasible for applications to biomass combustion and gasification. IR-DFWM spectra of CH3Cl, by probing ro-vibrational transitions belonging to the fundamental stretching modes v(1) and v(4), have been successfully recorded in gas flows diluted with nitrogen at atmospheric pressure and elevated temperatures up to 820K. In order to identify the spectral lines of CH3Cl, the recorded IR-DFWM spectra are compared with simulations using molecular parameters extracted from the HITRAN database. The potential interference from water vapor is discussed from measurements of H2O spectrum at 820K combined with simulations of H2O IR-DFWM spectrum based on the HITEMP database, and it was found that the (Q)Q(6) line of the v(1) band is relatively free from water interference at elevated temperatures. At atmospheric pressure, the detection limits for temperatures at 296, 550 and 820K were estimated to be 2.1, 3.1 and 6.2 (x10(15) molecules/cm(3)), respectively, by scanning the (Q)Q(6) line of the v(1) band. These results show the potential of interference free detection of CH3Cl with IR-DFWM in harsh environments like combustion. Copyright (c) 2015 John Wiley & Sons, Ltd.
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| 10. |
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