The kinetics of the reactions of the OH radical with propene and 1-butene are studied at T = 103 K. The low-temperature environment is provided by a pulsed Laval nozzle supersonic expansion of nitrogen with admixed radical precursor and reactant gases. The gas number density and temperature distributions in the flow are characterized by both dynamic pressure measurements and laser-induced fluorescence (LIF) spectroscopy of OH radicals excited in the (1,0) band of the A2Σ+−X2Πi transition. For the kinetic measurements, the OH radical decay profiles in the presence of reactants are monitored by LIF. The rate constants of the reactions of OH with propylene and 1-butene are measured at T = 103 K to be (0.81 ± 0.18) × 10-10 and (1.24 ± 0.27) × 10-10 cm3 molecule-1 s-1, respectively. The observed negative temperature dependences of the rate constants for both reactions studied by the pulsed Laval nozzle system show good agreement with both low-temperature and high-temperature kinetic data available in the literature.

A pulsed Laval nozzle, low Mach number supersonic expansion kinetics apparatus has been constructed to study neutral–neutral kinetics by a rather general laser photolysis initiation and laser photoionization detection of the product species. This new apparatus permits laboratory studies of low temperature rate coefficients (e.g., 70–170 K) on condensable gases that have insufficient vapor pressures at low temperatures for conventional methods of kinetic measurements. The design considerations, the uniformity of the reaction zone over 10–20 cm, and the skimmer sampling of the pulsed Laval expansion are examined. The direct measurement of a rate coefficient at 90 K is also demonstrated using this new apparatus.

The proportion of Korean ovarian cancer patients with a strong family history was significant, and the prevalence of BRCA1 and BRCA2 mutations in such patients was high.

Abstract. Photodynamic therapy ͑PDT͒ is a viable treatment option for a wide range of applications, including oncology, dermatology, and ophthalmology. Singlet oxygen is believed to play a key role in the efficacy of PDT, and on-line monitoring of singlet oxygen during PDT could provide a methodology to establish and customize the treatment dose clinically. This work is the first report of monitoring singlet oxygen luminescence in vivo in human subjects during PDT, demonstrating the correlation of singlet oxygen levels during PDT with the post-PDT photobiological response. Photodynamic therapy ͑PDT͒ is a viable treatment option for a variety of applications, including oncology, dermatology, and ophthalmology.1 In particular, 5-aminolevulinic acid ͑ALA͒-PDT is widely used to treat a range of dermatologic conditions.2 PDT is based on the interaction of a photosensitizer ͑PS͒, light, and oxygen, in which photoactivation of PS generates cytotoxic molecular species. Customized dosimetry could, in principle, impact the efficacy of treatment outcome and of the effective use of resources. Dosimetry in PDT is complex, as the treatment effect is generated by an interaction of multiple components.

Photodynamic therapy (PDT) is a promising cancer treatment. PDT uses the affinity of photosensitizers to be selectively retained in malignant tumors. When tumors, pretreated with the photosensitizer, are irradiated with visible light, a photochemical reaction occurs and tumor cells are destroyed. Oxygen molecules in the metastable singlet delta state O2(1Delta) are believed to be the species that destroys cancerous cells during PDT. Monitoring singlet oxygen produced by PDT may lead to more precise and effective PDT treatments. Our approach uses a pulsed diode laser-based monitor with optical fibers and a fast data acquisition system to monitor singlet oxygen during PDT. We present results of in vitro singlet oxygen detection in solutions and in a rat prostate cancer cell line as well as PDT mechanism modeling.

The need for patient-specific photodynamic therapy (PDT) in dermatologic and oncologic applications has triggered several studies that explore the utility of surrogate parameters as predictive reporters of treatment outcome. Although photosensitizer (PS) fluorescence, a widely used parameter, can be viewed as emission from several fluorescent states of the PS (e.g., minimally aggregated and monomeric), we suggest that singlet oxygen luminescence (SOL) indicates only the active PS component responsible for the PDT. Here, the ability of discrete PS fluorescence-based metrics (absolute and percent PS photobleaching and PS re-accumulation post-PDT) to predict the clinical phototoxic response (erythema) resulting from 5-aminolevulinic acid PDT was compared with discrete SOL (DSOL)-based metrics (DSOL counts pre-PDT and change in DSOL counts pre/post-PDT) in healthy human skin. Receiver operating characteristic curve (ROC) analyses demonstrated that absolute fluorescence photobleaching metric (AFPM) exhibited the highest area under the curve (AUC) of all tested parameters, including DSOL based metrics. The combination of dose-metrics did not yield better AUC than AFPM alone. Although sophisticated real-time SOL measurements may improve the clinical utility of SOL-based dosimetry, discrete PS fluorescence-based metrics are easy to implement, and our results suggest that AFPM may sufficiently predict the PDT outcomes and identify treatment nonresponders with high specificity in clinical contexts.

This paper describes a comprehensive, multispecies diagnostic suite for the characterization of chemical and electrical oxygen-iodine laser kinetics. Oxygen-iodine lasers involve reactions and energy transfer among several key species, including electronically excited O 2 (a) and O 2 (b), the reagent I 2 , ground-state I, electronically excited I * , and, in the case of electric-discharge driven systems, atomic oxygen. We have implemented highly sensitive and accurate methods for the measurement of all of these species in a chemically reacting flow system. We have used quantitative near-infrared emission spectroscopy to detect O 2 (a), O 2 (b), and I * , ultra-high precision absorption spectroscopy to detect I 2 , ultra-high precision tunable diode laser absorption spectroscopy to detect I:I * small-signal gain, and a chemiluminescent titration method to detect O. All of these methods provide well-resolved species concentrations, and the spectral emission and laser absorption measurements also provide spectroscopic determinations of gas temperature. Multispecies measurements of this type constrain reacting flow models so that gaps in our understanding of these systems can be identified and resolved. Through accurately calibrated spectral emission measurements, we have shown that high yields of O 2 (a) (>20%) can be attained via microwave discharge excitation of flowing dilute mixtures of O 2 and Ar. For these conditions, we have observed positive small-signal gain on the I *-I transition, however the multispecies concentration data clearly show the existence of previously unknown kinetics limitations related to the presence of O. We discuss the calibration and accuracy of the diagnostic methods, and the implications of the results for the kinetics of discharge-driven oxygen-iodine laser systems.

Photodynamic therapy (PDT) is a promising cancer treatment that involves optical excitation of photosensitizers that promote oxygen molecules to the metastable O 2 (a 1 Δ) state (singlet oxygen). This species is believed to be responsible for the destruction of cancerous cells during PDT. We describe a fiber optic-coupled, pulsed diode laser-based diagnostic for singlet oxygen. We use both temporal and spectral filtering to enhance the detection of the weak O 2 (a →X) emission near 1.27 µm. We present data that demonstrate real-time singlet oxygen production in tumor-laden rats with chlorin e6 and 5-aminolevulinic acid-induced protoporphyrin photosensitizers. We also observe a positive correlation between post-PDT treatment regression of the tumors and the relative amount of singlet oxygen measured. These results are promising for the development of the sensor as a real-time dosimeter for PDT.