Golo von Basum

Radboud University Nijmegen, Nijmegen, Provincie Gelderland, Netherlands

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Publications (14)22.44 Total impact

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    ABSTRACT: The level of exhaled carbon monoxide (eCO) is considered a marker of oxidative stress in diabetes. Previous findings indicated that eCO levels correlated with blood glucose level. The aim of this work was to apply and compare two independent analyzing methods for eCO after oral glucose administration. Glycemia, eCO, and exhaled hydrogen were measured before and after oral administration of glucose. Six healthy nonsmoking volunteers participated. For eCO analysis, we used two methods: a commercially available electrochemical sensor, and a high-precision laser spectrometer developed in our laboratory. The precision of laser-spectroscopic eCO measurements was two orders of magnitude better than the precision of the electrochemical eCO measurement. eCO levels measured by laser spectrometry after glucose administration showed a decrease of 4.1%+/-1.5% compared to the baseline (p<0.05). Changes in the eCO measured by the electrochemical sensor were not significant (p=0.08). Exhaled hydrogen levels increased by 40% within the first 10 min after glucose administration (p<0.05). The previous finding that the glycemia increase after glucose administration was associated with a significant increase in eCO concentrations was not confirmed. We propose that previous eCO measurements with electrochemical sensors may have been affected by cross sensitivity to hydrogen.
    Journal of Biomedical Optics 01/2008; 13(3):034012. · 2.75 Impact Factor
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    ABSTRACT: We present a high-power (2.75W), broadly tunable (2.75–3.83μm) continuous-wave optical parametric oscillator based on MgO-doped periodically poled lithium niobate. Automated tuning of the pump laser, etalon and crystal temperature results in a continuous wavelength coverage up to 450cm-1 per poling period at <5×10-4cm-1 resolution. The versatility of the optical parametric oscillator as a coherent light source in trace-gas detection is demonstrated with photoacoustic and cavity ring-down spectroscopy. A 17-cm-1-wide CO2 spectrum at 2.8μm and multi-component gas mixtures of methane, ethane and water in human breath were measured using photoacoustics. Methane (at 3.2μm) and ethane (at 3.3μm) were detected using cavity ring-down spectroscopy with detection limits of 0.16 and 0.07parts per billion by volume, respectively. A recording of 12CH4 and 13CH4 isotopes of methane shows the ability to detect both species simultaneously at similar sensitivities.
    Applied Physics B 01/2006; 85(2):173-180. · 1.78 Impact Factor
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    ABSTRACT: We present a ring-down absorption spectrometer based on a continuous-wave CO laser in the mid-infrared spectral region near lambda = 5 microm. Using a linear ring-down cavity (length: 0.5 m) with high reflective mirrors (R = 99.988 %), we observed a noise-equivalent absorption coefficient of 3 x 10(-10) cm(-1)Hz(-1/2). This corresponds to a noise-equivalent concentration of 800 parts per trillion (ppt) for (14)NO and 40 ppt for (15)NO in 1 s averaging time. We achieve a time resolution of 1 s which allows time resolved simultaneous detection of the two N isotopes. The delta(15)N value was obtained with a precision of +/-1.2 per thousand in a sample with a NO fraction of 11 ppm. The simultaneous detection enables the use of (15)NO as a tracer molecule for endogenous biomedical processes.
    Isotopes in Environmental and Health Studies 01/2006; 41(4):303-11. · 0.70 Impact Factor
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    D Halmer, G von Basum, P Hering, M Mürtz
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    ABSTRACT: We present a ringdown absorption spectrometer based on a continuous-wave CO laser in the mid-infrared spectral region near lambda = 5 microm. Using a linear ringdown cavity (length, 0.5 m) with R > = 99.99% mirrors, we observed a noise-equivalent absorption coefficient of 7 x 10(-11) cm(-1) Hz(-1/2). This is 2 orders of magnitude improved compared with previous values. With this setup we studied the spectroscopic detection of carbonyl sulfide (here abbreviated OCS) traces in ambient air and in exhaled breath. We achieved a detection limit of 7 parts in 10(12) (parts per trillion) OCS in ambient air, which is unprecedented and shows great promise for environmental and biomedical applications.
    Optics Letters 09/2005; 30(17):2314-6. · 3.39 Impact Factor
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    ABSTRACT: We present a frequency stability and linewidth analysis of two different setups of continuous-wave pump and signal-resonant optical parametric oscillators (pump resonant, singly resonant OPO, PR-SRO). Both designs, a common-cavity and a dual-cavity version, utilize a frequency-stable and narrow-linewidth pump laser and are stabilized without using an external reference. A long-term frequency stability better than 30MHz is reached over more than 30 minutes for both designs. The frequency jitter on a one-second time-scale is 56kHz for the common-cavity PR-SRO and about 10MHz for the dual-cavity PR-SRO. The short-term linewidths were measured using an external high-finesse cavity and are (92)kHz and (61)kHz in 20s, respectively. To our knowledge, these are the lowest values demonstrated so far for a widely continuously wavelength-tunable all-solid-state laser source.
    Applied Physics B 01/2005; 80(3):307-313. · 1.78 Impact Factor
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    ABSTRACT: A 2 W, continuous-wave, widely and continuous tunable, singly frequency, mid-infrared optical parametric oscillator is used in combination with cavity ring down spectroscopy for the fast and sensitive detection of trace gases.
    01/2005;
  • G. Von Basum, D. Halmer, P. Hering, M. Mürtz
    Breath Analysis for Clinical Diagnosis and Therapeutic Monitoring; 01/2005
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    ABSTRACT: An all-solid-state infrared trace gas sensor is presented combining a continuous-wave optical parametric oscillator (OPO) with Cavity Leak-Out spectroscopy (CALOS), a cw version of Cavity Ring Down spectroscopy. The PPLN based pump resonant, singly resonant OPO is pumped at 1064 nm (2 W). Dual cavity design allows to select any desired wavelength within the emission range of the OPO (3.1 - 3.8 μm) and to use different tuning schemes in order to scan absorption features. To detect the CALOS signals the OPO frequency is scanned over the cavity resonance at kHz rates. The high power of the OPO (up to 100 mW at each end of the cavity) allows a strong excitation of the TEM00 mode of the cavity, yielding large detector signals. A noise-equivalent absorption coefficient of 1.6*10-10cm-1/√Hz is reached for integration times up to 180 sec. This corresponds to a detection limit for ethane at sub-ppt level. Measurements at reduced pressure (100 mbar) combined with a scanning of the OPO over cm-1 wide regions allows a multi-gas analysis of ambient air and human breath samples without a cooling-trap.
    Proc SPIE 06/2004;
  • Daniel Halmer, Golo von Basum, Peter Hering
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    ABSTRACT: We report on a very fast fitting algorithm for single exponential functions which is based on the method of successive integration. The algorithm corrects the systematic error of trapezoidal integration. The new algorithm needs only 150 μs for a dataset of 1536 points and is around 700 times faster than the nonlinear Levenberg–Marquardt fit provided by LABVIEW. This makes it suitable for real-time instrumental use. Beside the better time resolution, the acceleration allows more averaging, which leads to higher precision. In our experiment instrumental sensitivity was improved by a factor of 3.7.
    Review of Scientific Instruments 05/2004; 75(6). · 1.60 Impact Factor
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    ABSTRACT: Spectroscopic detection of ethane in the 3-microm wavelength region was performed by means of a cw optical parametric oscillator and cavity leak-out. We achieved a minimum detectable absorption coefficient of 1.6 x 10(-10) cm 1/square root of Hz, corresponding to an ethane detection limit of 6 parts per trillion/square root of Hz. For 3-min integration time the detection limit was 0.5 parts per trillion. The levels are to our knowledge the best demonstrated so far. These frequency-tuning capabilities facilitated multigas analysis with simultaneous monitoring of ethane, methane, and water vapor in human breath.
    Optics Letters 05/2004; 29(8):797-9. · 3.39 Impact Factor
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    ABSTRACT: A method is described for rapidly measuring the ethane concentration in exhaled human breath. Ethane is considered a volatile marker for lipid peroxidation. The breath samples are analyzed in real time during single exhalations by means of infrared cavity leak-out spectroscopy. This is an ultrasensitive laser-based method for the analysis of trace gases on the sub-parts per billion level. We demonstrate that this technique is capable of online quantifying of ethane traces in exhaled human breath down to 500 parts per trillion with a time resolution of better than 800 ms. This study includes what we believe to be the first measured expirograms for trace fractions of ethane. The expirograms were recorded after a controlled inhalation exposure to 1 part per million of ethane. The normalized slope of the alveolar plateau was determined, which shows a linear increase over the first breathing cycles and ends in a mean value between 0.21 and 0.39 liter-1. The washout process was observed for a time period of 30 min and was modelled by a threefold exponential decay function, with decay times ranging from 12 to 24, 341 to 481, and 370 to 1770 s. Our analyzer provides a promising noninvasive tool for online monitoring of the oxidative stress status.
    Journal of Applied Physiology 01/2004; 95(6):2583-90. · 3.48 Impact Factor
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    ABSTRACT: We report a portable, all-solid-state, mid-infrared spectrometer for trace-gas analysis. The light source is a continuous-wave optical parametric oscillator based on PPLN and pumped by a Nd:YAG laser at 1064nm. The generated single-frequency idler output covers the wavelength region between 2.35 and 3.75μm. With its narrow line width, this light source is suitable for precise trace-gas analysis with very high sensitivity. Using cavity leak-out spectroscopy we achieved a minimum detectable absorption coefficient of 1.2×10-9/cm (integration time: 16s), corresponding, for example, to a detection limit of 300 parts per trillion ethane. This sensitivity and the compact design make this trace-gas analyzer a promising tool for various in situ environmental and medical applications.
    Applied Physics B 01/2002; 75(6):751-754. · 1.78 Impact Factor
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    ABSTRACT: We report the spectroscopic detection of formaldehyde in ambient air using cavity leak-out spectroscopy, a cw variant of cavity ring-down spectroscopy. This technique proved to be suitable for a real-time quantitative analysis of polluted air without any preprocessing of the air sample. Using a tunable CO-overtone sideband laser for the λ=3μm spectral region and a ring-down cell with R=99.95% mirrors, we achieved a detection limit of 2 parts per billion formaldehyde in ambient air, corresponding to a minimum detectable absorption coefficient of 7×10-9/cm (sampling time: 2 s). Calibration problems arising from the polarity of the molecule and due to HITRAN database uncertainties are discussed.
    Applied Physics B 01/2002; 75(2):311-316. · 1.78 Impact Factor
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    Golo von Basum
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    ABSTRACT: Diese Arbeit befasst sich mit der Weiterentwicklung eines Cavity-Leak-Out-Spektrometers (CALOS) für die höchstempfindliche Echtzeit-Spurengasanalytik, der Erweiterung des Einsatzgebiets dieser Methode für die medizinische Diagnostik durch Verwendung einer Strahlungsquelle im Bereich von 5µm Wellenlänge und dem Einsatz eines transportablen Festkörper-Lasers zusammen mit der CALOS-Technik. Bei der CALOS-Technik wird das Licht eines durchstimmbaren Lasers in einen optischen Resonator gefüllt, der aus zwei hochreflektierenden Spiegeln besteht. Nach Abschalten des Lasers wird das Abklingen der im Resonator gespeicherten Energie beobachtet. Wird ein absorbierendes Gas zwischen die Resonatorspiegel gebracht, klingt die Energie schneller ab. Aus dieser Zeitdifferenz können sehr geringe Absorptionen bestimmt werden. Im Wellenlängenbereich um 3µm wurde ein CO-Oberton-Laser eingesetzt, der schon bei früheren Arbeiten verwendet wurde. Die Empfindlichkeit des Spektrometers konnte um den Faktor 20 verbessert werden und beträgt z.B. für Ethan momentan 42ppt/Hz<sup>1/2</sup>. Bei Kooperationen mit verschiedenen medizinischen Arbeitsgruppen wurde der Einsatz des CALOS-Spektrometers getestet. Der Schwerpunkt lag dabei auf dem Nachweis von Ethan als Biomarker für den oxidativen Stress Status. Untersucht wurden zum einen kranke Patienten, wie z.B. Diabetiker oder Personen mit Nierenschädigungen, und zum anderen gesunden Probanden unter extremen Umständen, wie z.B. sportlicher Belastung, UV-Bestrahlung oder hyperbarem Sauerstoff. Dank speziell entwickelter Probenahmesysteme hat sich die Analysemethode bei allen Untersuchungen bewährt. Eine besondere Herausforderung für die Spurengasanalytik stellt die atemzugsaufgelöste Messung des menschlichen Atems bei gleichzeitig höchster Empfindlichkeit dar. Im Rahmen dieser Arbeit konnte diese Aufgabe mit dem CALOS-Spektrometer erstmals für den Ethannachweis erfüllt werden. Erreicht wurde eine Zeitauflösung von 790ms bei einer Nachweisgrenze von nur 500ppt Ethan. Mit diesen, bisher einzigartigen Fähigkeiten, eröffnen sich weitreichende neue Möglichkeiten für die medizinische Diagnostik. Es wurden Untersuchungen an Probanden durchgeführt, bei denen der zeitliche Konzentrationsverlauf atemzugsaufgelöst analysiert wurde. Dabei konnten erstmals Exspirogramme für Ethan aufgezeichnet werden. Um den Bereich der nachweisbaren Moleküle zu erweitern, wurde ein CO-Laser im Wellenlängenbereich um 5µm eingesetzt. Es konnte gezeigt werden, dass mit diesem Aufbau minimal nachweisbare Absorptionskoeffizienten bis zu 7x10<sup>-11</sup>cm<sup>-1</sup>/Hz<sup>1/2</sup> messbar sind. Um die Einsatzmöglichkeiten für die Spurengasanalytik zu demonstrieren, wurden die Detektionsgrenzen für OCS, NO und CO untersucht. Beim Nachweis von NO ist es möglich, nahezu simultan die Konzentration von <sup>14</sup>NO und <sup>15</sup>NO zu bestimmen. Dabei werden Nachweisgrenzen von 700ppt für <sup>15</sup>NO und 140ppb für <sup>14</sup>NO erreicht. Die Detektionsgrenzen sind für OCS mit 3ppt/Hz<sup>1/2</sup> und für CO mit 90ppt//Hz<sup>1/2</sup> mindestens eine Größenordnung besser als bei allen bisher bekannten Verfahren. Die Echtzeitfähigkeit des CALOS-Spektrometers konnte auch für die Experimente im 5µm Bereich genutzt werden. Abschließend wurde in einer Kooperation mit dem Institut für Angewandte Physik der Universität Bonn und dem Institut für Experimentalphysik der Universität Düsseldorf der Einsatz eines optisch-parametrischen Oszillators (OPO) für die CALOS-Spektroskopie evaluiert. Diese Lichtquelle liefert Strahlung im Wellenlängenbereich um 3µm. Es wurde eine bisher unerreichte Nachweisempfindlichkeit für Ethan von 6ppt/Hz<sup>1/2</sup> erzielt. Diese ist um mindestens eine Größenordnung besser als bei allen anderen bisher bekannten Methoden. Auch der Nachweis von Aceton wurde demonstriert. Insgesamt stellt der Einsatz des OPOs einen wichtigen Schritt in Richtung eines mobilen, schnellen und höchstempfindlichen Spurengasdetektors dar.