The measurement of volatile organic compounds during ICARTT 2004 and experimental studies of chlorine atom reactions with alpha- and beta-pinene

Proton transfer reaction mass spectrometry (PTR-MS) has been shown to be a reliable and efficient method for determining atmospheric mixing ratios of volatile organic compounds (VOCs). As a part of AIRMAP, two PTR-MS instruments were used in field and laboratory studies. A high sensitivity instrument showed improved limits of detection by 3-5 times when compared to a standard sensitivity instrument. Agreement for quantification of VOCs by PTR-MS to other methods was good. Average atmospheric mixing ratios, diurnal profiles, and deposition velocities of methanol, acetone, acetaldehyde, acetic acid, isoprene, alpha-pinene, beta-pinene, methylethyl ketone, methylvinyl ketone and methacrolein were determined at two locations in New England. Laboratory studies utilizing an environmental chamber and PTR-MS were used to identify and quantify products from the chlorine initiated oxidation of alpha- and beta-pinene. Products observed in the oxidation of alpha-pinene included pinonaldehyde (8%) and acetone (10%), and acetone (10%) for the beta-pinene case

PNA hybridizes to complementary oligonucleotides obeying the Watson-Crick hydrogen-bonding rules

DNA ANALOGUES are currently being intensely investigated owing to their potential as gene-targeted drugs1-3. Furthermore, their properties and interaction with DNA and RNA could provide a better understanding of the structural features of natural DNA that determine its unique chemical, biological and genetic properties3,4. We recently designed a DNA analogue, PNA, in which the backbone is structurally homomorphous with the deoxyribose backbone and consists of N-(2-aminoethyl)glycine units to which the nucleobases are attached5-9. We showed that PNA oligomers containing solely thymine and cytosine can hybridize to complementary oligonucleotides, presumably by forming Watson-Crick-Hoogsteen (PNA)2-DNA triplexes, which are much more stable than the corresponding DNA-DNA duplexes5-7, and bind to double-stranded DNA by strand displacement5,8. We report here that PNA containing all four natural nucleobases hybridizes to complementary oligonucleotides obeying the Watson-Crick base-pairing rules, and thus is a true DNA mimic in terms of base-pair recognition

Optimization of adsorptive removal of α-toluic acid by CaO2 nanoparticles using response surface methodology

The present work addresses the optimization of process parameters for adsorptive removal of α-toluic acid by calcium peroxide (CaO2) nanoparticles using response surface methodology (RSM). CaO2 nanoparticles were synthesized by chemical precipitation method and confirmed by Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis which shows the CaO2 nanoparticles size range of 5–15 nm. A series of batch adsorption experiments were performed using CaO2 nanoparticles to remove α-toluic acid from the aqueous solution. Further, an experimental based central composite design (CCD) was developed to study the interactive effect of CaO2 adsorbent dosage, initial concentration of α-toluic acid, and contact time on α-toluic acid removal efficiency (response) and optimization of the process. Analysis of variance (ANOVA) was performed to determine the significance of the individual and the interactive effects of variables on the response. The model predicted response showed a good agreement with the experimental response, and the coefficient of determination, (R2) was 0.92. Among the variables, the interactive effect of adsorbent dosage and the initial α-toluic acid concentration was found to have more influence on the response than the contact time. Numerical optimization of process by RSM showed the optimal adsorbent dosage, initial concentration of α-toluic acid, and contact time as 0.03 g, 7.06 g/L, and 34 min respectively. The predicted removal efficiency was 99.50%. The experiments performed under these conditions showed α-toluic acid removal efficiency up to 98.05%, which confirmed the adequacy of the model prediction