Products of the OH radical-initiated reactions of furan, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran in the presence of NO.

Products of the gas-phase reactions of OH radicals with furan, furan-d4, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran have been investigated in the presence of NO using direct air sampling atmospheric pressure ionization tandem mass spectrometry (API-MS and API-MS/MS), and gas chromatography with flame ionization and mass spectrometric detectors (GC-FID and GC-MS) to analyze samples collected onto annular denuders coated with XAD solid adsorbent and further coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine for derivatization of carbonyl-containing compounds to their oximes. The products observed were unsaturated 1,4-dicarbonyls, unsaturated carbonyl-acids and/or hydroxy-furanones, and from 2,5-dimethylfuran, an unsaturated carbonyl-ester. Quantification of the unsaturated 1,4-dicarbonyls was carried out by GC-FID using 2,5-hexanedione as an internal standard, and the measured molar formation yields were: HC(O)CH═CHCHO (dominantly the E-isomer) from OH + furan, 75 ± 5%; CH3C(O)CH═CHCHO (dominantly the E-isomer) from OH + 2-methylfuran, 31 ± 5%; HC(O)C(CH3)═CHCHO (a E-/Z-mixture) from OH + 3-methylfuran, 38 ± 2%; and CH3C(O)C(CH3)═CHCHO from OH + 2,3-dimethylfuran, 8 ± 2%. In addition, a formation yield of 3-hexene-2,5-dione from OH + 2,5-dimethylfuran of 27% was obtained from a single experiment, in good agreement with a previous value of 24 ± 3% from GC-FID analyses of samples collected onto Tenax solid adsorbent without derivatization.

Interactions of gaseous HNO3 and water with individual and mixed alkyl self-assembled monolayers at room temperature.

The major removal processes for gaseous nitric acid (HNO3) in the atmosphere are dry and wet deposition onto various surfaces. The surface in the boundary layer is often covered with organic films, but the interaction of gaseous HNO3 with them is not well understood. To better understand the factors controlling the uptake of gaseous nitric acid and its dissociation in organic films, studies were carried out using single component and mixtures of C8 and C18 alkyl self-assembled monolayers (SAMs) attached to a germanium (Ge) attenuated total reflectance (ATR) crystal upon which a thin layer of SiOx had been deposited. For comparison, diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) studies were also carried out using a C18 SAM attached to the native oxide layer on the surface of silicon powder. These studies show that the alkyl chain length and order/disorder of the SAMs does not significantly affect the uptake or dissociation/recombination of molecular HNO3. Thus, independent of the nature of the SAM, molecular HNO3 is observed up to 70-90% relative humidity. After dissociation, molecular HNO3 is regenerated on all SAM surfaces when water is removed. Results of molecular dynamics simulations are consistent with experiments and show that defects and pores on the surfaces control the uptake, dissociation and recombination of molecular HNO3. Organic films on surfaces in the boundary layer will certainly be more irregular and less ordered than SAMs studied here, therefore undissociated HNO3 may be present on surfaces in the boundary layer to a greater extent than previously thought. The combination of this observation with the results of recent studies showing enhanced photolysis of nitric acid on surfaces suggests that renoxification of deposited nitric acid may need to be taken into account in atmospheric models.

Infrared studies of the reaction of methanesulfonic acid with trimethylamine on surfaces.

Organosulfur compounds generated from a variety of biological as well as anthropogenic sources are oxidized in air to form sulfuric acid and methanesulfonic acid (MSA). Both of these acids formed initially in the gas phase react with ammonia and amines in air to form and grow new particles, which is important for visibility, human health and climate. A competing sink is deposition on surfaces in the boundary layer. However, relatively little is known about reactions after they deposit on surfaces. We report here diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) studies of the reaction of MSA with trimethylamine (TMA) on a silicon powder at atmospheric pressure in synthetic air and at room temperature, either in the absence or in the presence of water vapor. In both cases, DRIFTS spectra of the product surface species are essentially the same as the transmission spectrum obtained for trimethylaminium methanesulfonate, indicating the formation of the salt on the surface with a lower limit to the reaction probability of γ > 10(-6). To the best of our knowledge, this is the first infrared study to demonstrate this chemistry from the heterogeneous reaction of MSA with an amine on a surface. This heterogeneous chemistry appears to be sufficiently fast that it could impact measurements of gas-phase amines through reactions with surface-adsorbed acids on sampling lines and inlets. It could also represent an additional sink for amines in the boundary layer, especially at night when the gas-phase reactions of amines with OH radical and ozone are minimized.

Production of gas phase NO2 and halogens from the photolysis of thin water films containing nitrate, chloride and bromide ions at room temperature.

Nitrate and halide ions coexist in particles generated in marine regions, around alkaline dry lakes, and in the Arctic snowpack. Although the photochemistry of nitrate ions in bulk aqueous solution is well known, there is recent evidence that it may be more efficient at liquid-gas interfaces, and that the presence of other ions in solution may enhance interfacial reactivity. This study examines the 311 nm photolysis of thin aqueous films of ternary halide-nitrate salt mixtures (NaCl-NaBr-NaNO3) deposited on the walls of a Teflon chamber at 298 K. The films were generated by nebulizing aqueous 0.25 M NaNO3 solutions which had NaCl and NaBr added to vary the mole fraction of halide ions. Molar ratios of chloride to bromide ions were chosen to be 0.25, 1.0, or 4.0. The subsequent generation of gas phase NO2 and reactive halogen gases (Br2, BrCl and Cl2) were monitored with time. The rate of gas phase NO2 formation was shown to be enhanced by the addition of the halide ions to thin films containing only aqueous NaNO3. At [Cl(-)]/[Br(-)] ≤ 1.0, the NO2 enhancement was similar to that observed for binary NaBr-NaNO3 mixtures, while with excess chloride NO2 enhancement was similar to that observed for binary NaCl-NaNO3 mixtures. Molecular dynamics simulations predict that the halide ions draw nitrate ions closer to the interface where a less complete solvent shell allows more efficient escape of NO2 to the gas phase, and that bromide ions are more effective in bringing nitrate ions closer to the surface. The combination of theory and experiments suggests that under atmospheric conditions where nitrate ion photochemistry plays a role, the impact of other species such as halide ions should be taken into account in predicting the impacts of nitrate ion photochemistry.

Thermal and photochemical reactions of NO2 on chromium(III) oxide surfaces at atmospheric pressure.

While many studies of heterogeneous chemistry on Cr(2)O(3) surfaces have focused on its catalytic activity, less is known about chemistry on this surface under atmospheric conditions. We report here studies of the thermal and photochemical reactions of NO(2) on Cr(2)O(3) at one atm in air. In order to follow surface species, the interaction of 16-120 ppm NO(2) with a 15 nm Cr(2)O(3) thin film deposited on a germanium crystal was monitored in a flow system using attenuated total reflectance (ATR) coupled to a Fourier transform infrared (FTIR) spectrometer. Gas phase products were monitored in the effluent of an ~285 ppm NO(2)-air mixture that had passed over Cr(2)O(3) powder in a flow system. A chemiluminescence NO(y) analyzer, a photometric O(3) analyzer and a long-path FTIR spectrometer were used to probe the gaseous products. In the absence of added water vapor, NO(2) formed nitrate (NO(3)(-)) ions coordinated to Cr(3+). These surface coordinated NO(3)(-) were reversibly solvated by water under humid conditions. In both dry and humid cases, nitrate ions decreased during irradiation of the surface at 302 nm, and NO and NO(2) were generated in the gas phase. Under dry conditions, NO was the major gaseous product while NO(2) was the dominant species in the presence of water vapor. Heating of the surface after exposure to NO(2) led to the generation of both NO(2) and NO under dry conditions, but only NO(2) in the presence of water vapor. Elemental chromium incorporated into metal alloys such as stainless steel is readily oxidized in contact with ambient air, forming a chromium-rich metal oxide surface layer. The results of these studies suggest that active photo- and thermal chemistry will occur when boundary layer materials containing chromium(III) or chromium oxide such as stainless steel, roofs, automobile bumpers etc. are exposed to NO(2) under tropospheric conditions.

2-Formylcinnamaldehyde formation yield from the OH radical-initiated reaction of naphthalene: effect of NO(2) concentration.

Naphthalene, typically the most abundant polycyclic aromatic hydrocarbon in the atmosphere, reacts with OH radicals by addition to form OH-naphthalene adducts. These OH-naphthalene adducts react with O(2) and NO(2), with the two reactions being of equal importance in air at an NO(2) mixing ratio of ∼60 ppbv. 2-Formylcinnamaldehyde [o-HC(O)C(6)H(4)CH═CHCHO] is a major product of the OH radical-initiated reaction of naphthalene, with a yield from the reaction of OH-naphthalene adducts with NO(2) of ∼56%. We have measured, on a relative basis, the formation yield of 2-formylcinnamaldehyde from the OH radical-initiated reaction of naphthalene in air at average NO(2) concentrations of 1.2 × 10(11), 1.44 × 10(12), and 1.44 × 10(13) molecules cm(-3) (mixing ratios of 0.005, 0.06, and 0.6 ppmv, respectively). These NO(2) concentrations cover the range of conditions corresponding to the OH-naphthalene adducts reacting ∼90% of the time with O(2) to ∼90% of the time with NO(2). The 2-formylcinnamaldehyde formation yield decreased with decreasing NO(2) concentration, and a yield from the OH-naphthalene adducts + O(2) reaction of 14% is obtained based on a 56% yield from the OH-naphthalene adducts + NO(2) reaction. Based on previous measurements of glyoxal and phthaldialdehyde from the naphthalene + OH reaction and literature data for the OH radical-initiated reactions of monocyclic aromatic hydrocarbons, the reactions of OH-naphthalene adducts with O(2) appear to differ significantly from the OH-monocyclic adduct + O(2) reactions.

Kinetics of the reactions of OH radicals with 2- and 3-methylfuran, 2,3- and 2,5-dimethylfuran, and E- and Z-3-hexene-2,5-dione, and products of OH + 2,5-dimethylfuran.

Furan and alkylfurans are present in the atmosphere from direct emissions and in situ formation from other volatile organic compounds. The OH radical-initiated reactions of furan and alkylfurans have been proposed as relatively clean in situ sources of unsaturated 1,4-dicarbonyls, some of which are otherwise not readily available. Using a relative rate method, rate constants at 296 ± 2 K for the gas-phase reactions of OH radicals with 2- and 3-methylfuran, 2,3- and 2,5-dimethylfuran, and Z- and E-3-hexene-2,5-dione have been measured, of (in units of 10(-11) cm(3) molecule(-1) s(-1)): 2-methylfuran, 7.31 ± 0.35; 3-methylfuran, 8.73 ± 0.18; 2,3-dimethylfuran, 12.6 ± 0.4; 2,5-dimethylfuran, 12.5 ± 0.4; Z-3-hexene-2,5-dione, 5.90 ± 0.57; and E-3-hexene-2,5-dione, 4.14 ± 0.02. Products of the OH radical-initiated reaction of 2,5-dimethylfuran were investigated, with 3-hexene-2,5-dione being formed with molar yields of 24 ± 3% in the presence of NO and 34 ± 3% in the absence of NO. Direct air sampling atmospheric pressure ionization mass spectrometry showed the formation of additional products of molecular weight 114, attributed to CH(3)C(O)CH ═ CHC(O)OH and/or 5-hydroxy-5-methyl-2-furanone, and 128, attributed to CH(3)C(O)OC(CH(3)) = CHCHO.

Nitrate ion photolysis in thin water films in the presence of bromide ions.

Nitrate ions commonly coexist with halide ions in aged sea salt particles, as well as in the Arctic snowpack, where NO(3)(-) photochemistry is believed to be an important source of NO(y) (NO + NO(2) + HONO + ...). The effects of bromide ions on nitrate ion photochemistry were investigated at 298 ± 2 K in air using 311 nm photolysis lamps. Reactions were carried out using NaBr/NaNO(3) and KBr/KNO(3) deposited on the walls of a Teflon chamber. Gas phase halogen products and NO(2) were measured as a function of photolysis time using long path FTIR, NO(y) chemiluminescence and atmospheric pressure ionization mass spectrometry (API-MS). Irradiated NaBr/NaNO(3) mixtures show an enhancement in the rates of production of NO(2) and Br(2) as the bromide mole fraction (χ(NaBr)) increased. However, this was not the case for KBr/KNO(3) mixtures where the rates of production of NO(2) and Br(2) remained constant over all values of χ(KBr). Molecular dynamics (MD) simulations show that the presence of bromide in the NaBr solutions pulls sodium toward the solution surface, which in turn attracts nitrate to the interfacial region, allowing for more efficient escape of NO(2) than in the absence of halides. However, in the case of KBr/KNO(3), bromide ions do not appreciably affect the distribution of nitrate ions at the interface. Clustering of Br(-) with NO(3)(-) and H(2)O predicted by MD simulations for sodium salts may facilitate a direct intermolecular reaction, which could also contribute to higher rates of NO(2) production. Enhanced photochemistry in the presence of halide ions may be important for oxides of nitrogen production in field studies such as in polar snowpacks where the use of quantum yields from laboratory studies in the absence of halide ions would lead to a significant underestimate of the photolysis rates of nitrate ions.

Formation yields of glyoxal and methylglyoxal from the gas-phase OH radical-initiated reactions of toluene, xylenes, and trimethylbenzenes as a function of NO2 concentration.

Aromatic hydrocarbons comprise 20% of non-methane volatile organic compounds in urban areas and are transformed mainly by atmospheric chemical reactions with OH radicals during daytime. In this work we have measured the formation yields of glyoxal and methylglyoxal from the OH radical-initiated reactions of toluene, xylenes, and trimethylbenzenes over the NO2 concentration range (0.2-10.3) × 1013 molecules cm(-3). For toluene, o-, m-, and p-xylene, and 1,3,5-trimethylbenzene, the yields showed a dependence on NO2, decreasing with increasing NO2 concentration and with no evidence for formation of glyoxal or methylglyoxal from the reactions of the OH-aromatic adducts with NO2. In contrast, for 1,2,3- and 1,2,4-trimethylbenzene the glyoxal and methylglyoxal formation yields were independent of the NO2 concentration within the experimental uncertainties. Extrapolations of our results to NO2 concentrations representative of the ambient atmosphere results in the following glyoxal and methylglyoxal yields, respectively: for toluene, 26.0 ± 2.2% and 21.5 ± 2.9%; for o-xylene, 12.7 ± 1.9% and 33.1 ± 6.1%; for m-xylene, 11.4 ± 0.7% and 51.5 ± 8.5%; for p-xylene, 38.9 ± 4.7% and 18.7 ± 2.2%; for 1,2,3-trimethylbenzene, 4.7 ± 2.4% and 15.1 ± 3.3%; for 1,2,4-trimethylbenzene, 8.7 ± 1.6% and 27.2 ± 8.1%; and for 1,3,5-trimethylbenzene, 58.1 ± 5.3% (methylglyoxal).

Yields of glyoxal and ring-cleavage co-products from the OH radical-initiated reactions of naphthalene and selected alkylnaphthalenes.

Naphthalene and alkylnaphthalenes are the most abundant polycyclic aromatic hydrocarbons present in ambient air and are transformed mainly by chemical reaction with hydroxyl (OH) radicals during daylight hours. To better understand the reaction mechanisms, we have quantified glyoxal from the OH radical-initiated reactions of naphthalene, 1-methylnaphthalene, 1,4-dimethylnaphthalene, acenaphthene, and acenaphthylene as a function of the NO(2) concentration and, for the naphthalene reaction, also in the absence of NO(2). Glyoxal was formed as a first-generation product from the naphthalene, 1-methylnaphthalene, 1,4-dimethylnaphthalene, and acenaphthene reactions, and its yields were independent of the NO(2) concentration over the ranges employed, being 5% in the presence of NO(2) and 3% in the absence of NO(2) from naphthalene; approximately 3% from 1-methylnaphthalene; approximately 2% from 1,4-dimethylnaphthalene; approximately 10-15% from acenaphthene; and <2% from acenaphthylene. Second-generation formation of glyoxal was evident in the 1-methylnaphthalene, 1,4-dimethylnaphthalene, and acenaphthene reactions. For the naphthalene reaction, our results suggest that the reactions of the OH-naphthalene adducts with NO(2) and O(2) both lead to glyoxal formation in similar yield. Simultaneous measurements of phthaldialdehyde from naphthalene, 2-acetylbenzaldehyde from 1-methylnaphthalene, and 1,2-diacetylbenzene from 1,4-dimethylnaphthalene suggest that these C(n-2)-dicarbonyls are coproducts to glyoxal.

Formation and reactions of 2-formylcinnamaldehyde in the OH radical-initiated reaction of naphthalene.

2-Formylcinnamaldehyde [O-HC(O)C6H4CH=CHCHO] is a major product of the OH radical-initiated reaction of naphthalene, the atmospherically most abundant polycyclic aromatic hydrocarbon. Previous studies indicate that 2-formylcinnamaldehyde undergoes photolysis as well as reaction with OH radicals. We have used direct air sampling atmospheric pressure ionization mass spectrometry (API-MS) to monitor 2-formylcinnamaldehyde as its protonated molecular ion during OH radical-initiated reactions of naphthalene. From the time-dependent behavior of the 2-formylcinnamaldehyde signal, ratios of (2-formylcinnamaldehyde removal rate/naphthalene reaction rate) were determined over a range of approximately 3 in (OH radical concentration/ light intensity). With an estimated rate constant for the reaction of OH radicals with 2-formylcinnamaldehyde of 5.3 x 10(-11) cm3 molecule(-1) s(-1), the photolysis rate of 2-formylcinnamaldhyde by blacklamps was determined to be approximately equal to that of NO2. Photolysis of 2-formylcinnamaldehyde will be the dominant loss process in the atmosphere, with an estimated lifetime of 2-formylcinnamaldehyde of approximately 120 s at a solar zenith angle of 30 degrees. Our data were used to re-evaluate the previous 2-formylcinnamaldehyde measurements of Sasaki et al. (Environ. Sci. Technol. 1997, 31, 3173-3179) and derive a 2-formylcinnamaldehyde formation yield from the OH radical reaction of naphthalene in the presence of NO of 56(-10)(+15)%.

A brief parental education for shaping sleep habits in 4-month-old infants.

OBJECTIVE: To examine the effectiveness of a simple behavioral intervention with an educational booklet on the modification of parenting behaviors and the prevention of sleep disturbance in 4-month-old infants. DESIGN: A prospective cohort design with cluster sampling controls in a primary care setting. PARTICIPANTS: A total of 136 mothers with 4-month-old infants who visited a local health check-up clinic and responded to the 3-month follow-up survey. METHODS: At the health check-up, an intervention group was provided with 10 minutes of group guidance and a simple educational booklet designed to encourage parents to promote favorable sleep patterns in their infants. A control group was provided with standard education alone. The two groups were questioned 3 months later through a survey sent by mail. Main measurements were parenting behaviors of parents and night waking of infants. RESULTS: Two undesirable maternal behaviors that reinforce night waking in infants exhibited a significantly greater improvement in the intervention group than in the control group. "Feed or check diaper promptly" behavior and "hold and soothe immediately" behavior after "night waking" in the infant were significantly decreased in the intervention group. CONCLUSIONS: Our findings suggest that increased night waking in infants was prevented in the intervention group. Our results indicate that the proportion of infant night waking was significantly higher in the control group, and there was also a tendency toward an increase in the proportion of infants who woke frequently and cried. These infant behaviors were not changed in the intervention group at the 3-month follow-up stage.

Rate constants for the gas-phase reactions of OH radicals with a series of C6-C14 alkenes at 299 +/- 2 K.

Rate constants for the gas-phase reactions of OH radicals with the C(6)-C(14) 2-methyl-1-alkenes and the C(6)-C(10) trans-2-alkenes have been measured at 299 +/- 2 K and atmospheric pressure of air using a relative rate technique. The rate constants obtained (in units of 10(-11) cm(3) molecule(-1) s(-1)) were as follows: 2-methyl-1-pentene, 5.67 +/- 0.21; 2-methyl-1-hexene, 6.50 +/- 0.11; 2-methyl-1-heptene, 6.71 +/- 0.21; 2-methyl-1-octene, 7.02 +/- 0.16; 2-methyl-1-nonene, 7.28 +/- 0.21; 2-methyl-1-decene, 7.85 +/- 0.26; 2-methyl-1-undecene, 7.85 +/- 0.21; 2-methyl-1-dodecene, 7.96 +/- 0.26; 2-methyl-1-tridecene, 8.06 +/- 0.37; trans-2-hexene, 6.08 +/- 0.26; trans-2-heptene, 6.76 +/- 0.32; trans-2-octene, 7.23 +/- 0.21; trans-2-nonene, 7.54 +/- 0.16; and trans-2-decene, 7.80 +/- 0.26, where the indicated errors are two least-squares standard deviations and do not include the uncertainty associated with the rate constant for the reference compound alpha-pinene. Our data show that the rate constants for the reactions of OH radicals with 2-methyl-1-alkenes and trans-2-alkenes increase with increasing carbon number, suggesting that this is in part due to H-atom abstraction from the C-H bonds of the alkyl substituent groups. Combined with previous literature data for the reactions of OH radicals with a series of 1-alkenes, we propose that the increase in rate constant with increasing carbon number is due to H-atom abstraction from the C-H bonds of the alkyl substituent groups and to enhancement of the rate constant for OH radical addition to the C=C bond, which increases with carbon number of a C(n)-alkyl substituent group up to a maximum at approximately C(8).

[Impact of parenting behavior relevant to infant's sleep on maternal sleep and health].

BACKGROUND: Maternal health is affected by infant's sleep problems like night awakening or bedtime difficulties. Previous studies indicated that infant's sleep problems are affected by particular parenting behaviour (hereinafter referred to as parenting). However, the relation between maternal sleep and infant's sleep has been unclear and there is only limited information on the interaction between parenting, infant's sleep, maternal sleep, and maternal health. The purpose of this study was: 1. to examine the relationship between infant's sleep problems and maternal sleep and health; and 2. to investigate comprehensive relations of four parameters; maternal sleep, maternal health, infant's sleep, and parenting. METHODS: The subjects were 194 mothers who attended health checkup for 4month old infants. The questionnaire consisted of 3 components: 1) infant's and mother's sleep habits and sleep problems; 2) maternal health; 3) parenting. There were 15 items for parenting, divided into desirable and undesirable behavior. Subjects were classified into Problem Group (n = 40) or Control Group (n = 142) according to the infants' sleep problems. Maternal sleep, maternal health, parenting were compared between two groups. In addition, we examined relationships among the four parameters using path analysis. RESULTS: Over 60% of mothers experienced some sleep problems and about 30% were suspected of being at high risk of insomnia. The most common mother's sleep problem was "poor sleep quality". Over 80% of mothers had some health problems, that most frequently observed being "Shoulder stiffness". Desirable parenting like "Feed fully and checking the diaper before bedtime" was observed in 80% of mothers, while undesirable parenting like "Feeding or checking a diaper immediately" was seen in 71% of mothers. Maternal sleep problems, maternal health problems, and undesirable parenting were more frequent in the Problem Group than the Control Group. As a result of path analysis, the following relations were found: undesirable parenting affected infant's sleep problems, infant's sleep problems influenced maternal sleep, and mother's sleep influenced maternal health. CONCLUSIONS: Thirty percent of mothers were suspected of having sleep disorder and more than half practiced undesirable parenting. Undesirable parenting affected infant's sleep problems which in turn directly affected mothers' sleep and indirectly affected mother's health.

Formation of nitro products from the gas-phase OH radical-initiated reactions of toluene, naphthalene, and biphenyl: effect of NO2 concentration.

Aromatic hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), are released into the atmosphere principally during incomplete combustion and account for approximately 20% of nonmethane organic compounds in urban air. Reaction with OH radicals is the dominant atmospheric chemical loss process for aromatic hydrocarbons, leading mainly to the formation of an OH-aromatic or OH-PAH adduct which then reacts with O2 and/or NO2. For OH-monocyclic aromatic adducts, reaction with O2 dominates under atmospheric conditions; however, no data are available concerning the relative importance of reactions of OH-PAH adducts with O2 and NO2. We have measured formation yields of 3-nitrotoluene, 1- and 2-nitronaphthalene, and 3-nitrobiphenyl from the OH radical-initiated reactions of toluene, naphthalene, and biphenyl as a function of NO2 concentration. Our data showthatthe OH-aromatic adduct reactions with O2 and NO2 are of equal importance in the atmosphere at NO2 mixing ratios of approximately 3.3 ppmV for toluene, approximately 0.06 ppmV for naphthalene, and approximately 0.6 ppmV for biphenyl. Ambient concentrations of toluene, naphthalene, and biphenyl and their nitrated products measured at a site in the Los Angeles air basin are consistent with our laboratory measurements.

[Sleep of 4-month-old infants: bedtime, night waking and sleep problems].

BACKGROUND AND OBJECTIVES: Recently, Japanese infant's bedtime has become late and it is reported that this might have a bad influence on infant's growth. The purpose of the present study was to investigate the actual situation and interrelationships between night waking and other sleep problems in Japanese 4-month -old infant. METHODS: The subjects were 194 mothers and infants who participated in health checkups at four months after delivery in Fukuoka City. The questionnaire consisted of 3 components: 1) infant's and mother's sleep practices and sleep problems; 2) coping behavior for infant's sleep; 3) perceptions of child-care and maternal health. Their responses were linked to health checkup's results. The subjects were divided into two groups; Waking Group (n = 111) who was wakening one or more times from 0-6 a.m. and Sleeping Group (n = 83) who was sleeping throughout the night. The proportion of Waking Group was constituted 57.2% in all infants. Infant's growth, sleep, and sleep problems were compared between two groups. RESULTS: The mean infant's bedtime was 10:28 p.m., and the proportion of infants reported to go to bed at 10 p.m. or later was 69.4%. The proportion of infants with irregular bedtimes was 16.5%. Twenty-eight point six percent of infants had sleep problems like difficulty settling, severe night waking and were suspected to be high risk of sleep disorders. Infants in the Waking Group were found to have more numbers of sleep problems than in the Sleeping Group. The proportion with difficulty settling was higher in the Waking Group. Additionally, the proportion with irregular bedtimes was higher in the Waking Group. However, infant's height and weight did not significantly differ between two groups. CONCLUSIONS: Late bedtime and high proportion of night waking in 4-month-old infants were found to be characteristic in Fukuoka city. There is a possibility that night waking reflects delayed development of circadian rhythms.

Kinetics and products of the OH radical-initiated reaction of 3-methyl-2-butenal.

Kinetics and products of the gas-phase reaction of OH radicals with 3-methyl-2-butenal [(CH3)2C=CHCHO] have been investigated at room temperature and atmospheric pressure of air. Using a relative rate method with methacrolein as the reference compound, a rate constant for the reaction of OH radicals with 3-methyl-2-butenal of (6.21 +/- 0.18) x 10(-11) cm3 molecule(-1) s(-1) at 296 +/- 2 K was measured, where the indicated error does not include the uncertainty in the rate constant for the methacrolein reference compound. Products of this reaction were investigated using in situ Fourier transform infrared (FT-IR) spectroscopy and solid phase microextraction (SPME) fibers coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine for on-fiber derivatization of carbonyl compounds, with subsequent thermal desorption and analysis by gas chromatography. The products observed and the molar formation yields were: glyoxal, 40 +/- 3%; acetone, 74 +/- 6%; 2-hydroxy-2-methylpropanal, 4.6 +/- 0.7%; CO2, 39% initially, decreasing to 30% at greater extents of reaction; peroxyacyl nitrate(s) [RC(O)OONO2], 5-8%, increasing with the extent of reaction and with the sum of the CO2 and RC(O)OONO2 yields being 38 +/- 6%; and organic nitrates [RONO2], 8.5 +/- 2.3%. The formation of these products is readily explained by a reaction mechanism based on those previously formulated for the corresponding reactions of the alpha,beta-unsaturated aldehydes acrolein, crotonaldehyde and methacrolein. Based on the mechanism proposed, at room temperature H-atom abstraction from the CHO group accounts for 40 +/- 6% of the overall reaction, and OH radical addition to the carbon atoms of the C=C bond accounts for 53 +/- 4% of the overall reaction. Hence 93 +/- 8% of the reaction products and pathways are accounted for.