Kajian Awal Dekteksi Dini Penyakit dalam dengan Metode Non-invasive Spektroskopi Fotoakustik Laser

Telah dilakukan kajian awal deteksi dini penyakit dalam menggunakan spektrometer fotoakustik (SFA) laser yang dibangun di Laboratorium Fisika Atom-Inti Jurusan Fisika FMIPA UGM. Eksperimen dilakukan dengan metode pengambilan sampel yang non-invasive yaitu melalui hembusan nafas relawan. Analisa data dari hasil eksperimen dilakukan menggunakan metode Analisis Multikoponen Gas dengan menggunakan software Origin dan Matlab. Hasil analisis dapat menunjukkan tiga macam gas karakteristik berbeda yang dapat dipakai untuk mencirikan suatu jenis penyakit tertentu, yaitu gas Etilen, Aseton dan Amonia. Kata kunci: Fotoakustik laser dan Analisis multikomponen ga

Diode-laser Based Photo-acoustic Spectroscopy In Atmospheric No­2 Detection

We have developed a simple, low cost, and compact NO2 detection system. It\u27s based on photoacoustic spectroscopy (PAS) method uses a diode laser as a source of radiation. The PAS system has a detection limit of 10 ppbv for NO2. With this set-up we were able to detect the NO2 concentration from urban air near our campus. We have also investigated the NO2 dissociation effect on the PAS system via NO measurements using a direct absorption spectroscopy method on quantum cascade laser (QCL) system. Keywords: photoacoustic spectroscop

Continuous wave optical parametric oscillator for quartz-enhanced photoacoustic trace gas sensing

A continuous wave optical parametric oscillator, generating up to 300 mW idler output in the 3–4 μm wavelength region, and pumped by a fiber-amplified DBR diode laser is used for trace gas detection by means of quartz-enhanced photoacoustic spectroscopy (QEPAS). Mode-hop-free tuning of the OPO output over 5.2 cm-1 and continuous spectral coverage exceeding 16.5 cm-1 were achieved via electronic pump source tuning alone. Online monitoring of the idler wavelength, with feedback to the DBR diode laser, provided an automated closed-loop control allowing arbitrary idler wavelength selection within the pump tuning range and locking of the idler wavelength with a stability of 1.7×10-3 cm-1 over at least 30 min.\ud \ud Using this approach, we locked the idler wavelength at an ethane absorption peak and obtained QEPAS data to verify the linear response of the QEPAS signal at different ethane concentrations (100 ppbv-20 ppmv) and different power levels. The detection limit for ethane was determined to be 13 ppbv (20 s averaging), corresponding to a normalized noise equivalent absorption coefficient of 4.4×10-7 cm-1  W/Hz1/2

Small-Size Resonant Photoacoustic Cell of Inclined Geometry for Gas Detection

A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window background and noise are analyzed in demonstration experiments as functions of the modulation frequency for a prototype cell with the internal volume ~ 0.5 cm^3. The minimal detectable absorption for the prototype is estimated to be ~ 1.2 10^{-8} cm^{-1} W Hz^{-1/2}.Comment: 11 pages, 5 figure

Laser spectroscopy for breath analysis : towards clinical implementation

Detection and analysis of volatile compounds in exhaled breath represents an attractive tool for monitoring the metabolic status of a patient and disease diagnosis, since it is non-invasive and fast. Numerous studies have already demonstrated the benefit of breath analysis in clinical settings/applications and encouraged multidisciplinary research to reveal new insights regarding the origins, pathways, and pathophysiological roles of breath components. Many breath analysis methods are currently available to help explore these directions, ranging from mass spectrometry to laser-based spectroscopy and sensor arrays. This review presents an update of the current status of optical methods, using near and mid-infrared sources, for clinical breath gas analysis over the last decade and describes recent technological developments and their applications. The review includes: tunable diode laser absorption spectroscopy, cavity ring-down spectroscopy, integrated cavity output spectroscopy, cavity-enhanced absorption spectroscopy, photoacoustic spectroscopy, quartz-enhanced photoacoustic spectroscopy, and optical frequency comb spectroscopy. A SWOT analysis (strengths, weaknesses, opportunities, and threats) is presented that describes the laser-based techniques within the clinical framework of breath research and their appealing features for clinical use.Peer reviewe

Laser photoacoustic detection allows in planta detection of nitric oxide in tobacco following challenge with avirulent and virulent Pseudomonas syringae pathovars.

We demonstrate the use of laser photoacoustic detection (LPAD) as a highly sensitive method to detect in planta nitric oxide ( . NO) production from tobacco (Nicotiana tabacum . NO 1 O 3 / NO 2 1 O 2 ). The utility of the LPAD method was shown by examination of a nonhost hypersensitive response and a disease induced by Pseudomonas syringae (P. s.) pv phaseolicola and P. s. pv tabaci in tobacco. . NO was detected within 40 min of challenge with P. s. pv phaseolicola, some 5 h before the initiation of visible tissue collapse. The wildfire tobacco pathogen P. s. pv tabaci initiated . NO generation at 2 h postinfection. The use of . NO donors, the scavenger CPTIO ([4-carboxyphenyl]-4,5-dihydro-4,4,5,5-tetramethyl-3-oxide), and the mammalian nitric oxide synthase inhibitor L-NMMA (N G -monomethyl-L-arginine) indicated that . NO influenced the kinetics of cell death and resistance to both avirulent and virulent bacteria in tobacco. These observations suggest that

SAM levels, gene expression of SAM synthetase, methionine synthase and ACC oxidase, and ethylene emission from N. suaveolens flowers

S′adenosyl-l-methionine (SAM) is a ubiquitous methyl donor and a precursor in the biosynthesis of ethylene, polyamines, biotin, and nicotianamine in plants. Only limited information is available regarding its synthesis (SAM cycle) and its concentrations in plant tissues. The SAM concentrations in flowers of Nicotiana suaveolens were determined during day/night cycles and found to fluctuate rhythmically between 10 and 50 nmol g−1 fresh weight. Troughs of SAM levels were measured in the evening and night, which corresponds to the time when the major floral scent compound, methyl benzoate, is synthesized by a SAM dependent methyltransferase (NsBSMT) and when this enzyme possesses its highest activity. The SAM synthetase (NsSAMS1) and methionine synthase (NsMS1) are enzymes, among others, which are involved in the synthesis and regeneration of SAM. Respective genes were isolated from a N. suaveolens petal cDNA library. Transcript accumulation patterns of both SAM regenerating enzymes matched perfectly those of the bifunctional NsBSMT; maximum mRNA accumulations of NsMS1 and NsSAMS1 were attained in the evening. Ethylene, which is synthesized from SAM, reached only low levels of 1–2 ppbv in N. suaveolens flowers. It is emitted in a burst at the end of the life span of the flowers, which correlates with the increased expression of the 1-aminocyclopropane-1-carboxylate oxidase (NsACO)