Abstract  The nomadic herding population of the Darhad Valley, in northern Mongolia, collects and utilizes a salt precipitate, called hujir, which develops at the saline system, Tohi. This culturally important indigenous dietary supplement is consumed daily as an ingredient in a salty milk-tea and because of its essential micro- and macronutrients it is a beneficial and necessary part of their daily diet. Despite its benefits, there are increasing health concerns among the Darhad people as a result of consuming hujir. Therefore, we conducted a dietary risk assessment. Consumption rates were obtained from interviews with nomadic herders of the valley and a chronic exposure assessment was completed using chemical analyses on hujir samples. A combination of chronic toxicity threshold values, dietary reference intake recommendations, and drinking water guidelines were used to estimate dietary risks related to hujir consumption. Exposures to arsenic, fluoride, and nitrate were as high as 33, 1.2, and 1.3 times the chronic oral reference dose, respectively. Exposures to antimony, arsenic, and lead were 1.7, 19, and 14 times the drinking water guidelines, respectively. Given these results, additional studies are needed to better understand possible health effects associated with hujir consumption in the Darhad population, especially for arsenic.

Abstract  An ultrasensitive chronoamperometric method for quantitative determination of trace amounts of lead (down to 20 ppb) in acidic solutions is proposed in this paper. The method is based on observations that a complete under-potentially deposited (UPD) lead layer inhibits the electroreduction of nitrate on a bare Cu(111) electrode. To asses the limits of the method, both the electroreduction of nitrate and UPD of lead monolayer on copper single (111) and polycrystalline electrodes in perchloric acidic solution are studied by means of cyclic voltammetry, chronoamperometry, and rotating disk electrode (RDE) experiments. It is found that an inexpensive polycrystalline copper electrode is sensitive enough for analytical detection of lead traces in electrolytes down to 1 x 10(-8) M. Analytical results obtained by the proposed method in 2 orders of magnitude concentration range are compared to atomic absorption spectroscopy measurements to evaluate and assess the sensitivity of the employed experimental protocol. The excellent match between both analytical approaches validates the applicability of the proposed method.

Abstract  A study was made of the sandy and loamy soils of the woodland areas of the Wielkopolski National Park (Poland) affected by acid rain. The basic properties of the soils were determined, revealing their strong acidification, poor buffering power, and the possibility of aluminium release. An analysis was made of the content of soluble, exchangeable, organic, amorphous, and free forms of aluminium. The concentration of exchangeable aluminium exceeded that of the form dissolved in soil water several times to tens of times. In soil solutions Ca/Al ratios in some horizons show very low values that could induce a nutrient deficit. In the sandy profiles the ratio even drops below the critical level of 0.1. In the surface horizon the dominant cation at all the sites is the aluminium ion. An analysis of anions shows a dominance of sulphate and chloride ions. In autumn nitrites were recorded at all depth levels, while in spring only in the surface layers. The highest fluoride concentrations were found to occur in profiles situated the closest to the emission source of fluorine compounds. The markedly higher concentrations of ammonium than nitrate ions can lead to increased acidification and eutrophication of the soil. (C) Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved.

Abstract  Ozone and UV/O3 were employed to mineralize dinitrotoluene (DNT) isomers and 2,4,6-trinitrotoluene (TNT) in spent acid from toluene nitration process. The oxidative degradation tests were carried out to elucidate the influence of various operating variables on the performance of mineralization of total organic compounds (TOC) in spent acid, including reaction temperature, intensity of UV (254 nm) irradiation, dosage of ozone and concentration of sulfuric acid. It is remarkable that the nearly complete mineralization of organic compounds can be achieved by ozonation combined with UV irradiation. Nevertheless, the hydroxyl radicals (OH) would not be generated by either ozone decomposition or photolysis of ozone under the experimental condition of this study. According to the spectra identified by gas chromatograph/mass spectrometer (GC/MS) and further confirmed by gas chromatograph/flame ionization detector (GC/FID), the multiple oxidation pathways of DNT isomers are given, which include o-, m-, p-mononitrotoluene (MNT) and 1,3-dinitrobenzene, respectively. In addition, oxidative degradation of 2,4,6-TNT leads to a 1,3,5-trinitrobenzene intermediate.

Abstract  Additive or multiplicative models of crop response on which salinity management theory have been developed may lead to an erroneous perception regarding compensative interaction among salinity and other growth factors. We present results from studies of biomass production and transpiration of corn (Zea mays L. cv. Jubilee), melon (Cucumis melo L. subsp. meto cv. Galia), tomato (Lycopersicon esculentum Mill. cv. 5656), onion (Allium cepa L. cv. HA 944), and date palms (Phoenix dactylifera L. cv. Medjool) under salinity combined with water or nitrate (growth promoters) or with boron (growth inhibitor). The measured crop responses were to the more severe stress rather than to combinations of the individual effects of the various stresses. Consequences of shifting management of saline water to a dominant factor approach include reduction of environmental contamination and conservation of water resources.

Abstract  Despite reduction in its exposure, lead remains a major health problem. The primary target of lead toxicity is the central nervous system. The cellular, intracellular and molecular mechanisms of lead neurotoxicity are numerous, such as induction of apoptosis and interfering with Ca2+ dependent enzyme like nitric oxide synthase (NOS). To investigate the cytotoxic effect of lead on rat pheochromocytoma (PC12) cells, as a suitable model for neuroscience study, and possible correlation between lead toxicity and nitric oxide (NO) production, this study was performed. The current results showed that lead could induce cytotoxicity as well as NO production in a dose dependent manner in PC12 cells after 24h. The cytotoxicity was positively correlated with increased NO, (nitrite and nitrate) production in these cells. L-NAME, a NOS inhibitor, treatment (2.5 mM) could reverse this cytotoxicity. It can be concluded that lead-induced cytotoxicity in PC12 cells could partly be mediated by higher NO production. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

Abstract  Parkinson's disease ( PD) is characterized by progressive degeneration of dopaminergic neurons and a substantial decrease in the neurotransmitter dopamine in the nigro-striatal region of the brain. Increased markers of oxidative stress, activated microglias and elevated levels of pro-inflammatory cytokines have been identified in the brains of patients with PD. Although the precise mechanism of loss of neurons in PD remains unclear, these findings suggest that microglial activation may contribute directly to loss of dopaminergic neurons in PD patients. In the present study, we tested the hypothesis that activated microglia induces nitric oxide-dependent oxidative stress which subsequently causes death of dopaminergic neuronal cells in culture. We employed lipopolysaccharide ( LPS) stimulated mouse macrophage cells ( RAW 264.7) as a reactive microglial model and SH-SY5Y cells as a model for human dopaminergic neurons. LPS stimulation of macrophages led to increased production of nitric oxide in a time and dose dependent manner as well as subsequent generation of other reactive nitrogen species such as peroxynitrite anions. In co-culture conditions, reactive macrophages stimulated SH-SY5Y cell death characterized by increased peroxynitrite concentrations and nitration of alpha-synuclein within SH-SY5Y cells. Importantly 1400W, an inhibitor of the inducible nitric oxide synthase provided protection from cell death via decreasing the levels of nitrated alpha-synuclein. These results suggest that reactive microglias could induce oxidative stress in dopaminergic neurons and such oxidative stress may finally lead to nitration of alpha-synuclein and death of dopaminergic neurons in PD.

Abstract  STUDY OBJECTIVE: To determine the safety and efficacy of diltiazem CD 180 mg administered once/day in patients with chronic stable angina inadequately controlled with P-blockers, long-acting nitrates, or both. DESIGN: Multicenter, randomized, double-blind, placebo-controlled, parallel-group trial. SETTING: Medical clinics in the private and academic sectors. PATIENTS: Of 172 patients, 170 completed the 2-week double-blind treatment period. INTERVENTION: . Patients received either diltiazem CD 180 mg or placebo once/day in combination with existing antianginal therapy. MEASUREMENTS AND MAIN RESULTS: The time to termination of exercise tolerance testing, 24 hours after the dose increased significantly in the diltiazem CD group (37.2 sec) compared with the placebo group (21.3 sec, p=0.0438). Time to onset of angina during exercise testing also increased (57.6 vs 35.0 sec, respectively, p=0.0324), as did time to moderate angina (37.5 vs 20.6 sec, respectively, p=0.0354). The rates of total angina attacks and of angina attacks on exertion were significantly reduced in the diltiazem CD group versus placebo (p<0.05). Significant reductions in systolic and diastolic blood pressures and heart rate-blood pressure product measured at rest, submaximum exercise, and exercise termination were observed in diltiazem CD-treated patients compared with placebo (p<0.05). The frequency of treatment-related adverse events was identical in the two groups, 15.1%. CONCLUSION: Diltiazem CD 180 mg once/day is an effective, safe, and beneficial initial dosage when added to existing antianginal therapy.

Abstract  In this research the applicability of two different water quality concepts, a QUAL2E-based and a RWOM1-based water quality model is evaluated in terms of management decisions. The Dender river in Belgium serves as a case study for the application of the methodology. By using sensitivity analysis on both model concepts the important processes are revealed. Further, the differences between the predictions for a future scenario are analysed. The scenario chosen here is a reduction in fertiliser use of 90%, which reduces the diffuse pollution. This way, the advantages or disadvantages of using one concept against the other for this scenario are formulated. It was found that the QUAL-based models are more focussing on algae processes while the RWQM1 also takes into account processes in the sediment. Further the QUAL-based models are easier to calibrate, especially when only a small amount of data is available. Both concepts lead to more or less the same conclusions. However for some periods the differences become important and to reduce the uncertainty in those periods, more efforts should be spent in calibration and in better detection of parameters concerning sediment processes and diffusion.

Abstract  The derivatization method of thiazolidine-4-carboxylic acid (TZCA) and methyl-thiazolidine-4-carboxylic acid (Me-TZCA) in urine with alcohol/chloroformate was achieved. TZCA and Me-TZCA were derivatized in one step in urine with ethyl chloroformate in 1 min at room temperature. The derivatives of TZCA and Me-TZCA had very good chromatographic properties and offered very sensitive response for gas chromatography-electron impact ionization-mass spectrometry (GC-EI-MS). On the basis of derivatization, the method for simultaneous determination of TZCA and Me-TZCA in human urine was developed. Deuterated Me-TZCA (Me-TZCA-d4) was synthesized as the internal standard (IS) for the analysis of urine samples. TZCA and Me-TZCA were derivatized and extracted from urine at pH 9.5 with toluene, and then the dried extract was dissolved with 100 µl ethyl acetate and injected in GC/MS system. The recoveries of TZCA and Me-TZCA were about 102 and 103%, respectively, at the concentration of 0.05 mg/l. The method detection limits (MDL) were 1.0 and 0.5 µg/l, respectively, for TZCA and Me-TZCA in 1 ml human urine. The coefficients of variation of TZCA and Me-TZCA were less than 6% at the concentrations of 0.05 and 0.2 mg/l, respectively. To assess the formation of TZCA during inhalation with formaldehyde (FA) (about 3.1 and 38.1 ppm FA in air), urine samples from rats were taken during 3 days after initiation of treatment. The mean amount of TZCA determined was 0.07 mg/l in control group and 0.18 mg/l during treatment with 3.1 ppm. The TZCA levels increased up to about 1.01 mg/l during treatment with 38.1 ppm. It is planned to study whether urinary TZCA can be used as an indicator in the biological monitoring of exposure to FA.

Abstract  Uncomplicated urinary tract infections (uUTIs) are common in adult women across the entire age spectrum, with mean annual incidences of approximately 15% and 10% in those aged 15-39 and 40-79 years, respectively. By definition, UTIs in males or pregnant females and those associated with risk factors known to increase the risk of infection or treatment failure (e.g. acquisition in a hospital setting, presence of an indwelling urinary catheter, urinary tract instrumentation/interventions, diabetes mellitus or immunosuppression) are not considered herein. The majority of uUTIs are caused by Escherichia coli (70-95%), with Proteus mirabilis, Klebsiella spp. and Staphylococcus saprophyticus accounting for 1-2%, 1-2% and 5-10% of infections, respectively. If clinical signs and symptoms consistent with uUTI are present (e.g. dysuria, frequency, back pain or costovertebral angle tenderness) and there is no vaginal discharge or irritation present, the likelihood of uUTI is >90-95%. Laboratory testing (i.e. urinary nitrites, leukocyte esterase, culture) is not necessary in this circumstance and empirical treatment can be initiated. The ever-increasing incidence of antimicrobial resistance of the common uropathogens in uUTI has been and is a continuing focus of intensive study. Resistance to cotrimoxazole (trimethoprim/sulfamethoxazole) has made the empirical use of this drug problematic in many geographical areas. If local uropathogen resistance rates to cotrimoxazole exceed 10-25%, empirical cotrimoxazole therapy should not be utilized (fluoroquinolones become the new firstline agents). In a few countries, uropathogen resistance rates to the fluoroquinolones now exceed 10-25%, rendering empirical use of fluoroquinolones problematic. With the exception of fosfomycin (a second-line therapy), single-dose therapy is not recommended because of suboptimal cure rates and high relapse rates. Cotrimoxazole and the fluoroquinolones can be administered in 3-day regimens.... [ABSTRACT FROM AUTHOR] Copyright of Drugs is the property of ADIS International Limited and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)

Abstract  A novel approach to synthesize a single-phase orthorhombic perovskite, (La0.9Sr0.1) (Cr-0.85 Fe-0.05 Co0.05Ni0.05)O3-delta, is reported. Samples are synthesized using two groups of precursors, metal nitrates and metal acetates by various routes of sol-gel method. The effects of the anion and synthesis route on the perovskite structure and removal of impurity phase are investigated using X-ray diffractometry and Fourier-transform infrared spectroscopy. Impurity phases, SrCrO4 and CoCr2O4 are observed only for the samples prepared using metal nitrates and ascribed due to the pH dependence of citric acid and the cation-anion bonding character, which also affect the reactivity of the mixed solvents. Variation in cell volume with route is corroborative with route-dependent high frequency stretching modes. A mechanism using a partial-charge model is proposed to explain the results. (c) 2007 Elsevier B.V. All rights reserved.

Abstract  Introduction: Hyperbaric oxygen (HBO) therapy is known to increase oxygen concentration in tissues leading to induction of an adaptive increase in antioxidants, stimulation of angiogenesis, improvement of white blood cell action, and regulation of inflammatory process. Therefore, we tested the potential beneficial effect of HBO in neonatal rat model of necrotizing enterocolitis (NEC). Materials and Methods: Thirty newborn Sprague-Dawley rats, provided by the Experimental Research Council, Gulhane Military Medical Academy, Ankara,Turkey, were randomly divided into 3 groups as follows: NEC, NEC + HBO, and control. Necrotizing enterocolitis was induced by enteral formula feeding and exposure to hypoxia after cold stress at 4 degrees C and oxygen. The NEC + HBO group received HBO at 2.8 atmosphere absolute (ATA) for 90 minutes daily for 3 days. The pups were killed on the fourth day, and their intestinal tissues were harvested for biochemical and histopathologic analysis. Blood samples were also obtained from the pups. Results: The mortality rate was highest in the NEC group (3 pups in the NEC group vs I pup in the NEC + HBO group). Malondialdehyde and protein carbonyl content were significantly increased, whereas superoxide dismutase and glutathione peroxidase were significantly decreased in the NEC group. All these changes were similar to control levels in the NEC group by HBO treatment. Nitrate plus nitrite (NO.) levels and serum tumor necrosis factor a were increased in the NEC group and histopathologic injury score and apoptosis index in the NEC group were significantly higher than in the NEC + HBO group. Conclusion: Hyperbaric oxygen significantly reduced the severity of NEC in our study. (C) 2009 Elsevier Inc. All rights reserved.

Abstract  Herein, we report the first detailed study of ²⁰⁹Bi solid-state NMR (SSNMR) spectroscopy of extremely broad central transition powder patterns. ²⁰⁹Bi ultrawideline SSNMR spectra of several bismuth-containing materials (bismuth oxyhalides, bismuth nitrate pentahydrate, nonaaquabismuth triflate, and bismuth acetate) were acquired at field strengths of 9.4 and 21.11 using frequency-stepped techniques. The ²⁰⁹Bi SSNMR experiments at 9.4 T yield powder patterns with breadths ranging from 0.9 to 14.6 MHz, from which quadrupolar coupling constants, CQ²⁰⁹Bi), between 78 and 256 MHz, were extracted via analytical simulations. The breadths of the quadrupolar-dominated spectra and overall experimental times are greatly reduced for experiments conducted at 21.1 T, which yield high signal-to-noise spectra in which the smaller effects of bismuth chemical shift anisotropy can be clearly observed. The ²⁰⁹Bi electric field gradient (EFG) and chemical shift (CS) tensor parameters extracted from these spectra are correlated to the molecular structures at the bismuth sites, via first principles calculations of ²⁰⁹Bi EFG and CS tensors performed using CASTEP for periodic solids and Gaussian 03 for molecular clusters. The rapidity with which ²⁰⁹Bi SSNMR spectra can be acquired at ultrahigh fields, the sensitivity of the ²⁰⁹Bi NMR parameters to the bismuth environment, and the predictive power of theoretically calculated NMR interaction tensors suggest that ²⁰⁹Bi SSNMR may be useful for the characterization of a variety of Bi-containing materials and compounds. [ABSTRACT FROM AUTHOR] Copyright of Journal of the American Chemical Society is the property of American Chemical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract  A bimolecular rate constant, k(OH+Benzyl alcohol), of (28 +/- 7) x 10 (12) cm(3) molecule (1) s(-1) was measured using the relative rate technique for the reaction of the hydroxyl radical (OH) with benzyl alcohol, at (297 +/- 3)K and 1 atm total pressure. Additionally, an upper limit of the bimolecular rate constant, k(O3+Benzyl alcohol), of approximately 6 x 10(-19)cm(3) molecule(-1) s (1) was determined by monitoring the decrease in benzyl alcohol concentration overtime in an excess of ozone (O-3). To more clearly define part of benzyl alcohol's indoor environment degradation mechanism, the products of the benzyl alcohol + OH were also investigated. The derivatizing agents O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and N,O-bis(trimethylsilyl) tr fluoroacetamide (BSTFA) were used to positively identify benzaldehyde, glyoxal and 4-oxopentanal as benzyl alcohol/OH reaction products. The elucidation of other reaction products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible benzyl alcohol/OH reaction mechanisms based on previously published volatile organic compound/OH gas-phase reaction mechanisms. Published by Elsevier Ltd.

Abstract  mdash;: In acute myocardial ischemia, regional blood flow and function are proportionally reduced. With prolongation of ischemia, function further declines at unchanged blood flow. We studied the involvement of an inflammatory signal cascade in such progressive dysfunction and whether dysfunction is intrinsic to cardiomyocytes. In 10 pigs, ischemia was induced by adjusting inflow into the cannulated left anterior coronary artery to reduce coronary arterial pressure to 45 mm Hg (ISCH); 4 pigs received the inducible nitric oxide synthase (iNOS) inhibitors aminoguanidine or l-N6-(1-iminoethyl)-lysine during ISCH (ISCH+iNOS-Inhib); 6 pigs served as controls (SHAM). Anterior (AW) and posterior (PW) systolic wall thickening (sonomicrometry) were measured. After 6 hours, nitric oxide (NO) synthase (NOS) protein expression, NOS activity, and NO metabolites (nitrite/nitrate/nitroso species) were quantified in biopsies isolated from AW and PW. Cardiomyocyte shortening and intracellular calcium (Indo-1 acetoxymethyl ester) were measured without and with the NOS substrate l-arginine (100 [mu]mol/L). In ISCH, AW wall thickening decreased from 42+/-4% (baseline) to 16+/-3% (6 hours). Wall thickening remained unchanged in ISCH-PW and SHAM-AW/PW. NOS2 (iNOS) protein expression and activity, but not NOS3 (endothelial NO synthase), were increased in ISCH-AW and ISCH-PW. iNOS expression correlated with increased nitrite contents. Cardiomyocyte shortening was reduced in ISCH-AW versus SHAM-AW (4.4+/-0.3% versus 5.6+/-0.3%). l-Arginine reduced cardiomyocyte shortening further in ISCH-AW (to 2.8+/-0.2%) and ISCH-PW (3.4+/-0.4% versus 5.4+/-0.4%) but not in SHAM or in ISCH+iNOS-Inhib; intracellular [Ca2+] remained unchanged. With l-arginine, in vitro AW cardiomyocyte shortening correlated with in vivo AW wall thickening (r=0.72). In conclusion, sustained regional ischemia induces myocardial iNOS expression in pigs, which contributes to contractile dysfunction at the cardiomyocyte level., (C) 2008 American Heart Association, Inc.

Abstract  Several fog episodes occurred in California's San Joaquin Valley during winter 2000/2001. Measurements revealed the fogs to generally be less than 50 m deep, but to contain high liquid water contents (frequently exceeding 200 mg/m(3)) and large droplets. The composition of the fog water was dominated by ammonium (median concentration = 608 mu N), nitrate (304 mu N), and organic carbon (6.9 ppmC), with significant contributions also from nitrite (18 mu N) and sulfate (56 mu N). Principal organic species included formate (median concentration = 32 mu N), acetate (31 mu N), and formaldehyde (21 mu M). High concentrations of ammonia resulted in high fog pH values, ranging between 5.8 and 8.0 at the core measurement site. At this high pH aqueous phase oxidation of dissolved sulfur dioxide and reaction of S(IV) with formaldehyde to form hydroxymethanesulfonate are both important processes. The fogs are also effective at scavenging and removal of airborne particulate matter. Deposition velocities for key solutes in the fog are typically of the order of 1-2 cm/s, much higher than deposition velocities of precursor accumulation mode aerosol particles. Variations were observed in deposition velocities for individual constituents in the order NO2-> fogwater > NH4+> TOC similar to SO42 > NO3-. Nitrite, observed to be enriched in large fog drops, had a deposition velocity higher than the average fogwater deposition velocity, due to the increase in drop settling velocity with size. Species enriched in small fog drops (NH4+, TOC, SO42-, and NO3-) all had deposition velocities smaller than observed for fogwater. Typical boundary layer removal rates for major fog solute species were estimated to be approximately 0.5-1 mu g m(-3) h(-1), indicating the important role regional fogs can play in reducing airborne pollutant concentrations.

Abstract  Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts

Abstract  Nitric acid (HNO3) and ozone (O3), secondary products of photochemical reactions of nitrogen oxides (NOx) and volatile organic compounds, are important pollutants in arid regions with large outputs from petrol combustion. In the Los Angeles (LA) air basin, nitrogen dry deposition rates in forests downwind of the urban areas can reach 35-40 kg ha-1 year-1, roughly equivalent to the amount of N used to fertilize agricultural fields. The marked decline in the lichen population of the LA air basin has previously been attributed to local O3 concentration gradients, which overlaid the patterns of species extirpation. Recent research in the air basin has shown that nitrate (NO3-) deposition gradients run parallel to the O3 concentration gradient, and that deposition of NO3- and HNO3 can have significant effects on forest health. Our research examines the effects of HNO3 dry deposition on the lichen Ramalina menziesii Tayl. in an effort to understand the loss of lichen species in southern California, and increase the usefulness of lichens as biomonitors of nitrogen pollutants. We transplanted healthy R. menziesii thalli from a "pristine" location into fumigation chambers and exposed them to HNO3 under humid and dry conditions, and moderate and high HNO3 fumigations. R. menziesii thalli treated with HNO3 in month-long fumigations experienced a significant decline in chlorophyll content and carbon exchange capacity compared to thalli in control chambers. Leachate conductivity, NO3- and K+ concentrations increased with HNO3 fumigation levels and time. We conclude that R. menziesii has an unequivocally negative response to HNO3 gas concentrations common to ambient summer conditions in the LA air basin.

Abstract  Dew was collected in Santiago City at different locations and over different surfaces. High pHs (ca 7.0) and nitrite concentrations were observed in all the samples, irrespective of the location of the sampler and the material of the collecting surface. pH of the samples correlates with sulfate, nitrate and ammonium concentrations. This parameter is the most important determinant of the amount of nitrite present in the collected dew. This suggests that transfer from the gas phase Could be relevant in HONO capture. The increase in nitrite concentrations in dew collected during the period from 1995 to 2006 can be explained in terms of an increase in the average samples' pH along this period. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  Up to 60 million people working indoors experience symptoms such as eye, nose and throat irritation, headache, and fatigue. Investigations into these complaints have ascribed the effects to volatile organic compounds (VOCs) emitted from building materials, cleaning formulations, or other consumer products. New compounds can result when the VOCs react with hydroxyl or nitrate radicals or ozone present in indoor environments. Several oxygenated organic compounds, such as glyoxal, methylglyoxal, glycolaldehyde, and diacetyl, have been identified as possible reaction products of indoor environment chemistry. Although research has previously identified diacetyl and glyoxal as sensitizers, additional experiments were conducted in these studies to further classify their sensitization potential. Sensitization potential of these four compounds was assessed using quantitative structure-activity relationship (QSAR) programs. Derek for Windows and National Institute for Occupational Safety and Health logistic regression predicted all compounds to be sensitizers, while TOPKAT 6.2 predicted all compounds except for methylglyoxal. All compounds were tested in a combined irritancy and local lymph node assay (LLNA). All compounds except for glyoxal were found to be irritants and all tested positive in the LLNA with EC3 values ranging from 0.42 to 1.9%. Methylglyoxal significantly increased both the B220(+) and IgE(+)B220(+) cell populations in the draining lymph nodes and total serum IgE levels. The four compounds generated by indoor air chemistry were predicted by QSAR and animal modeling to be sensitizers, with the potential for methylglyoxal to induce IgE. The identification of these compounds as sensitizers may help to explain some of the health effects associated with indoor air complaints.

Abstract  Open-ocean and surf-zone sea-salt aerosol (SSA) emissions algorithms are incorporated in the CAMx aerosol model and applied over an area with an extended Archipelago (Greece), with a fine grid nested over the highly populated Attica peninsula. The maximum indirect impact of SSA on PM10 mass (35%) is located over a marine area with moderate SSA production and elevated shipping emissions (central Aegean Sea) where SSA interacts with anthropogenic nitric acid forming sodium nitrate. SSA increases PM10 levels in the Athens city center up to 27% during stable onshore winds. Under such conditions both open-ocean and surf-zone mechanisms contribute to aerosol production over Attica. A hybrid scheme for gas-to-particle mass transfer is necessary for accurately simulating semi-volatile aerosol components when coarse SSA is included. Dynamically simulating mass transfer to the coarse particles leads to a quadrupling of predicted PM10 nitrate in the Athens city center and up to two orders of magnitude in its coarse mass in comparison to using a bulk equilibrium approach. ABSTRACT FROM AUTHOR Copyright of Atmospheric Chemistry & Physics Discussions is the property of European Geosciences Union and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)

Abstract  Modeling systems that are designed to investigate tropospheric air quality concerns must address several issues simultaneously: ozone, particulate matter, deposition and visibility. These modeling systems consist of three components: meteorology, emissions and air quality. A simulation was conducted for the July 1999 Southern Oxidants Study to evaluate one such modeling system, Models-3. Performance of the meteorological component, MM5, was evaluated against observations. Consistency of two emissions models, SMOKE and EPS 2.5, was evaluated by comparing their outputs. For comparison, the performance of CMAQ and three additional models (CMAQ-MADRID 1, CMAQ-MADRID 2, and REMSAD) was evaluated for the same time period. Nested simulations for a 32-km and an 8-km grid were conducted for CMAQ and CMAQ-MADRID 1. Results for CMAQ-MADRID 2 and REMSAD are available only for the 8-km grid. Performance was evaluated for PM and its components, ozone and wet deposition. Differences in model performance for PM2.5 and its components were greatest for OC and total PM2.5; performance was more consistent for the other components. Model performance was generally better on the 32-km grid than the 8-km grid for PM2.5 and its components. R-2 values ranged from 20 to 50% for NH4+ and EC and were lower for other PM2.5 components, indicating that the predictive capabilities of the models for PM2.5 are limited. Model performance for ozone met EPA guidance for MNB and MNE when a 60 ppb cutoff was used and was better on the 8-km grid than on the 32-km grid. Performance for wet deposition was good.

Abstract  Comamonas sp. strain JS765 can grow with nitrobenzene as the sole source of carbon, nitrogen, and energy. We report here the sequence of the genes encoding nitrobenzene dioxygenase (NBDO), which catalyzes the first step in the degradation of nitrobenzene by strain JS765. The components of NBDO were designated Reductase(NBZ), Ferredoxin(NBZ), Oxygenase(NBZalpha), and Oxygenase(NBZbeta), with the gene designations nbzAa, nbzAb, nbzAc, and nbzAd, respectively. Sequence analysis showed that the components of NBDO have a high level of homology with the naphthalene family of Rieske nonheme iron oxygenases, in particular, 2-nitrotoluene dioxygenase from Pseudomonas sp. strain JS42. The enzyme oxidizes a wide range of substrates, and relative reaction rates with partially purified Oxygenase(NBZ) revealed a preference for 3-nitrotoluene, which was shown to be a growth substrate for JS765. NBDO is the first member of the naphthalene family of Rieske nonheme iron oxygenases reported to oxidize all of the isomers of mono- and dinitrotoluenes with the concomitant release of nitrite.

Abstract  This work reports a genetic analysis of the expression of nitrobenzene dioxygenase (NBDO) in Comamonas sp. strain JS765 and 2-nitrotoluene dioxygenase (2NTDO) in Acidovorax sp. strain JS42. Strains JS765 and JS42 possess identical LysR-type regulatory proteins, NbzR and NtdR, respectively. NbzR/NtdR is homologous to NahR, the positive salicylate-responsive transcriptional activator of the naphthalene degradation genes in Pseudomonas putida G7. The genes encoding NBDO and 2NTDO in each strain are cotranscribed, and transcription starts at the same site within identical promoter regions for each operon. Results from a lacZ reporter gene fusion demonstrated that expression of NBDO and 2NTDO is induced by multiple aromatic compounds, including an array of nitroaromatic compounds (nitrobenzene, 2-, 3-, and 4-nitrotoluene, 2,4- and 2,6-dinitrotoluene, and aminodinitrotoluenes), as well as salicylate and anthranilate. The nitroaromatic compounds appear to be the actual effector molecules. Analysis of beta-galactosidase and 2NTDO activities with strain JS42 demonstrated that NtdR was required for induction by all of the inducing compounds, high basal-level expression of 2NTDO, and complementation of a JS42 ntdR null mutant. Complementation with the closely related regulators NagR (from Ralstonia sp. strain U2) and NahR restored only induction by the archetype inducers, salicylate or salicylate and anthranilate, respectively, and did not restore the high basal level of expression of 2NTDO. The mechanism of 2NTDO gene regulation in JS42, and presumably that of NBDO gene regulation in JS765, appear similar to that of NahR-regulated genes in Pseudomonas putida G7. However, NbzR and NtdR appear to have evolved a broader specificity in JS42 and JS765, allowing for recognition of nitroaromatic compounds while retaining the ability to respond to salicylate and anthranilate. NtdR is also the first example of a nitroarene-responsive LysR-type transcriptional activator.