The gas-phase reaction of hydrazine and ozone: A nonphotolytic source of OH radicals for measurement of relative OH radical rate constants

The homogeneous gas-phase reaction of N₂H₄ with O₃ in air atmospheric pressure has been used to generate OH radicals in the dark, allowing the determination of relative OH radical rate constants for compounds which photolyze rapidly. This technique was first validated by determining the OH radical rate constant ratios for n-butane/cyclohexane and methanol/dimethyl ether, both of which are in excellent agreement with the literature values. The rate constant for the reaction of OH radicals with methyl nitrite at 300 ± 3 K was then determined relative to those for the reaction of OH radicals with n-hexane and dimethyl ether. The resulting rate constant of 1.8 × 10^?13 cm³/molecule·s is about seven times lower than those of previous measurements which employed a different nonphotolytic relative rate method.     

Quinoxalines and related compounds—X : The formation of indolo[2,3-b]quinoxalines and 2-p-aminophenyl-3-anilinoquinoxalines from 2-anilinoquinoxalines

The reactions which occur when 2-chloroquinoxaline is heated with an excess of aromatic amine are unexpectedly complex. For example, when 2-chloroquinoxaline is heated with excess aniline a mixture of the expected anilino derivative (1), 6H-indolo[2,3-b]quinoxaline (7), 2,3-dianilinoquinoxaline (11), and 2-p-ainino-phenyl-3-anilinoquinoxaline (16) is obtained.     

An investigation of the dark formation of nitrous acid in environmental chambers

The formation of nitrous acid (HONO) in the dark from initial concentrations of NO₂ of 0.1–20 ppm in air, and the concurrent disappearance of NO₂, were monitored quantitatively by UV differential optical absorption spectroscopy in two different environmental chambers of ca.4300- and 5800-L volume (both with surface/volume ratios of 3.4 m^?1). In these environmental chambers the initial HONO formation rate was first order in the NO₂ concentration and increased with the water vapor concentration. However, the HONO formation rate was independent of the NO concentration and relatively insensitive to temperature. The initial pseudo-first-order consumption rate of NO₂ was (2.8 ± 1.2) × 10^?4 min^?1 in the 5800-L Teflon-coated evacuable chamber and (1.6 ± 0.5) × 10^?4 min^?1 in a 4300-L all-Teflon reaction chamber at ca.300 K and ca.50% RH. The initial HONO yields were ca.40–50% of the NO₂ reacted in the evacuable chamber and ca.10–30% in the all-Teflon chamber. Nitric oxide formation was observed during the later stages of the reaction in the evacuable chamber, but ca.50% of the nitrogen could not be accounted for, and gas phase HNO₃ was not detected. The implications of these data concerning radical sources in environmental chamber irradiations of NO_x? organic-air mixtures, and of HONO formation in polluted atmospheres, are discussed.     

Some relationships between the correlation coefficients of planar sources and of their far fields

Two new correlation coefficients are introduced, that characterize the correlations between the spatial frequency components of the source distribution and of the field distribution respectively, in the plane of a two-dimensional source. It is then shown that except possibly for a simple phase factor depending on the magnitudes of the spatial frequencies, the two correlation coefficients are equal to each other. It is further shown that the degree of spatial coherence of the far field generated by the source is equal, except possibly for a simple geometrical phase factor, to either of the two new correlation coefficients relating to the distributions in the source plane.     

Investigation of a novel solid-phase chemiluminescent analytical system, incorporating photographic detection, for the measurement of glucose

A method has been developed for the rapid determination of substances by use of solid-phase reagents and a luminescence indicator reaction coupled with photographic detection of the light. The viability of the assay has been demonstrated for glucose estimations. The method uses small sample sizes (5-20 mul) and shows good sensitivity, e.g., detection of glucose down to 28 nmole.     

Rapid comparison of diacetylmorphine on banknotes by tandem mass spectrometry

A procedure is described for the determination of the distribution of the contamination of banknotes with controlled drugs using tandem mass spectrometry. The method is illustrated using diacetylmorphine, which is the major active component of heroin. A series of banknotes is introduced into the mass spectrometer and the intensities of two product ions (m/z 328 and 268) derived from the precursor protonated molecule (m/z 370) are recorded. A banknote is considered contaminated if it shows a significant peak for both product ions, and if the ratio of intensities of these two peaks falls within accepted limits. The distribution of diacetylmorphine on sterling banknotes taken from general circulation within the UK can be modelled by an arcsin (square root) transformation of the data or by a log transformation of the data with a higher proportion of contamination. The two models were found to be in close agreement, predicting an upper limit (at 99.9% confidence) of contamination on banknotes from general circulation between 9 and 10%. The percentage contamination in a case study was calculated and compared to the background distribution using the two models proposed. This comparison revealed that the contamination present in the case study was inconsistent with that present on banknotes in general circulation.     

Enhanced relaxation of nanoparticle-bound supercoiled DNA in X-ray radiation

A therapeutic methodology was developed based on the large X-ray absorption cross-section of gold nanoparticles at high photon energies (>81 keV). Experimental results showed that the amounts of the relaxed circular supercoiled DNA (scDNA) for gold nanoparticle-bound scDNA were more than doubled compared to that for free scDNA under otherwise identical radiation conditions.     

Kinetics of the reactions of O3 and OH radicals with furan and thiophene at 298 ± 2 K

Rate constants for the reactions of O₃ and OH radicals with furan and thiophene have been determined at 298 ± 2 K. The rate constants obtained for the O₃ reactions were (2.42 ± 0.28) × 10^?18 cm³/molec·s for furan and <6 ×10^?20 cm³/molec·s for thiophene. The rate constants for the OH radical reactions, relative to a rate constant for the reaction of OH radicals with n-hexane of (5.70 ± 0.09) × 10^?12 cm³/molec·s, were determined to be (4.01 ± 0.30) × 10^?11 cm³/molec·s for furan and (9.58 ± 0.38) × 10^?12 cm³/molec·s for thiophene. There are to date no reported rate constant data for the reactions of OH radicals with furan and thiophene or for the reaction of O₃ with furan. The data are compared and discussed with respect to those for other alkenes, dialkenes, and heteroatom containing organics.