Here again, diadsorbed seems preferable to complex,6 but good evidence supports surface intermediates which resemble -bonded diene and allyl.3-6We suggest that bicyclononane-dio and -d\% result from exchange of h,h and g,g. Adamantane (bicyclononane with carbon atoms 3 and 7 bridged by methylene) exchanges only one hydrogen atom per period of adsorption. Since all of its vicinal hydrogen atoms are rigidly staggered, this accords with predictions.2 Accordingly, the atoms at carbon atom 9 in bicyclononane will not exchange in conjunction with others barring some transannular reaction. In exchange of 1,1,3,3tetramethylcyclohexane on palladium,7 there is a maximum at da in addition to one at d¡ which results from alternation between A and B. Formation of bicyclononane-dio and -du is consistent with the proposal7 that dw in cyclopentane and d-a in tetramethylcyclohexane result from alternation between -bonded olefin and -bonded allyl. This cannot exchange h' and g'.These experiments were run in a flow apparatus with 5% palladium-on-alumina catalyst2 previously reduced in hydrogen at 350°. The partial pressures were cyclopentane, 93 mm.; bicyclononane, 8 mm.; adamantane, 5 mm.; and deuterium to 1 atm.Acknowledgment. This work was supported by the Petroleum Research Fund of the American Chemical Society, Grant 1579-C. We thank Dr.
Measurements of ambient levels of PAN (peroxyacetyl nitrate or, more properly, peroxyacetic nitric anhydride), C2–C5 alkyl nitrates, NOx (NO+NO2), HNO3, and NO3− particulates were made concurrently with a measurement of total reactive nitrogen species (NOy) at Scotia, Pennsylvania, from July 16 to August 31, 1988. Each of the organic nitrates exhibited a marked diurnal variation. The concentration of PAN varied from 0.05 to 3 ppbv (parts per billion by volume). The sum of the alkyl nitrate concentrations varied from less than 2 to 200 pptv (parts per trillion by volume). The NOy levels varied from 1 to 30 ppbv. During periods of high photochemical activity the contributions to NOy were 30–45% from HNO3, 20–25% from PAN, 15–25% from NOx, 5% from NO3−, and an additional 1.5% from the C2–C5 alkyl nitrates, on average. During these periods, about 15% of the measured NOy could not be accounted for by the sum of the individually measured species. The unidentified species that constitute this 15% exhibit behavior similar to that of the measured organic nitrates.
The mole fraction solubilities of ten copper(II) and five chromium(III) P-diketonates were measured in supercritical carbon dioxide with a spectroscopic technique and found to vary over 4 orders of magnitude. Observed trends indicate that the solubility in supercritical carbon dioxide is strongly dictated by the character of the hydrocarbon or fluorocarbon shell surrounding the central metal atom. A group-contribution approach was used to calculate the solubility parameter of the anion of the uncomplexed P-diketone that was correlated to the experimentally measured solubility. A regular solutions approach was used for Cr(acac)3 to quantitatively attempt to predict the solubility in supercritical carbon dioxide. Solubility data, solubility parameter trends, and limitations of regular solutions theory applied to supercritical fluids are discussed.1992, 64, 2875.
Measles remains an important cause of childhood mortality worldwide. Sustained high vaccination coverage is the key to preventing measles deaths. Because measles vaccine is delivered by injection, hurdles to high coverage include the need for trained medical personnel and a cold chain, waste of vaccine in multidose vials and risks associated with needle use and disposal. Respiratory vaccine delivery could lower these barriers and facilitate sustained high coverage. We developed a novel single unit dose, dry powder live-attenuated measles vaccine (MVDP) for respiratory delivery without reconstitution. We tested the immunogenicity and protective efficacy in rhesus macaques of one dose of MVDP delivered either with a mask or directly intranasal with two dry powder inhalers, PuffHaler and BD Solovent. MVDP induced robust measles virus (MeV)-specific humoral and T-cell responses, without adverse effects, which completely protected the macaques from infection with wild-type MeV more than one year later. Respiratory delivery of MVDP was safe and effective and could aid in measles control.aerosol delivery | protective immunity | multifunctional T cells | antibody avidity M easles is a highly contagious viral disease. Before the availability of measles virus (MeV) vaccines, more than 130 million cases and 7-8 million deaths occurred annually. Intensive immunization efforts with the live attenuated measles vaccine (LAMV) given by injection have resulted in substantial decreases in global measles disease. However, with an estimated 164,000 deaths in 2008 (1), measles continues to be an important cause of child mortality, especially in less-developed regions of the world. The key to prevention of measles is achieving and sustaining high levels of population immunity through vaccination, and substantial challenges for high coverage remain in many countries. Some of the challenges to providing a first dose of measles vaccine to at least 95% of each birth cohort, plus a second dose to older children, are related to the method of vaccine delivery.Measles vaccine is given by injection, and this creates hurdles to sustained high coverage in many developing countries. First, there is often a shortage of the trained personnel needed for sterile reconstitution and safe injection of vaccine. Second, in most developing countries, lyophilized vaccine is in 5-10 dose vials that, after reconstitution, lose 30-50% potency in an hour at 37°C (2), so unused doses must be discarded. Third, contaminated needles and syringes create risks for transmitting bloodborne disease and require safe disposal.As a potential improvement, respiratory delivery of reconstituted liquid LAMV has been studied for more than three decades (3) but has never been licensed or widely used. Aerosol administration of aqueous vaccine is highly effective in boosting preexisting antibody and holds promise for use in older children (4-11), but primary humoral and cellular immune responses vary with the age of vaccinees (12-15).We have developed a dry powder formulation of ...
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