Pau-rosa (Aniba rosaeodora Ducke) Lauraceae): informações sobre o sistema de plantio e o manejo sustentável da espécie.

Dados da espécie. Produtividade. Valor econômico. Produção de mudas e plantio de pau-rosa. Produção de biomassa. Produção de essência a partir de folhas e galhos.

Prevalence of Asthma Symptoms and Associated Factors in Schoolchildren from Brazilian Amazon Islands

Objectives. To determine the prevalence of asthma symptoms among schoolchildren living on two different Brazilian Amazon islands and to identify the risk factors related to this condition. Methods. A cross-sectional study of 400 schoolchildren (5-8 years old) using written questionnaires produced by the International Study of Asthma and Allergies in Childhood, a skin prick test (allergic sensitization), and a stool examination (for helminthic infection). Nonparametric tests were carried out, and the risk factors were identified by logistic regression. Results. the prevalence of active asthma symptoms was markedly higher in children living on Outeiro Island (OI) than those living on Comb Island (CBI) (30.5% and 16.5%, respectively). the logistic regression identified several risk factors of asthma symptoms on CBI: parental history of asthma, night coughing in the past year, and currently have a cat. On OI, the major risk factors were parental history of asthma, personal history of eczema, having two or more older siblings, and night coughing in the past year. the risk factors in common on both the islands were night coughing in the past year and parental history of asthma. Conclusions. the prevalence of asthma symptoms was higher in those with a lifestyle closer to that observed in urban areas (i.e., better sanitation and hygiene), reinforcing the protective effect of a rural environment. Different risk factors were associated with asthma symptoms in schoolchildren living on OI and on CBI. This fact may reflect the environmental individuality and particularities of each island.

An investigation into the tropospheric chemistry of acidic aerosols and ammonia in the laboratory

This thesis describes a broad range of experiments based on an aerosol flow-tube system to probe the interactions between atmospherically relevant aerosols with trace gases. This apparatus was used to obtain simultaneous optical and size distribution measurements using FTIR and SMPS measurements respectively as a function of relative humidity and aerosol chemical composition. Heterogeneous reactions between various ratios of ammonia gas and acidic aerosols were studied in aerosol form as opposed to bulk solutions. The apparatus is unique, in that it employed two aerosol generation methods to follow the size evolution of the aerosol while allowing detailed spectroscopic investigation of its chemical content. A novel chemiluminescence apparatus was also used to measure [NH4+]. SO2.H2O is an important species as it represents the first intermediate in the overall atmospheric oxidation process of sulfur dioxide to sulfuric acid. This complex was produced within gaseous, aqueous and aerosol SO2 systems. The addition of ammonia, gave mainly hydrogen sulfite tautomers and disulfite ions. These species were prevalent at high humidities enhancing the aqueous nature of sulfur (IV) species. Their weak acidity is evident due to the low [NH4+] produced. An increasing recognition that dicarboxylic acids may contribute significantly to the total acid burden in polluted urban environments is evident in the literature. It was observed that speciation within the oxalic, malonic and succinic systems shifted towards the most ionised form as the relative humidity was increased due to complete protonisation. The addition of ammonia produced ammonium dicarboxylate ions. Less reaction for ammonia with the malonic and succinic species were observed in comparison to the oxalic acid system. This observation coincides with the decrease in acidity of these organic species. The interaction between dicarboxylic acids and ‘sulfurous’/sulfuric acid has not been previously investigated. Therefore the results presented here are original to the field of tropospheric chemistry. SHO3-; S2O52-; HSO4-; SO42- and H1,3,5C2,3,4O4-;C2,3,4O4 2- were the main components found in the complex inorganic-organic systems investigated here. The introduction of ammonia produced ammonium dicarboxylate as well as ammonium disulfite/sulfate ions and increasing the acid concentrations increased the total amount of [NH4+].

Broadband optical cavity absorption spectroscopy in the near-ultraviolet: applications in atmospheric chemistry

A novel spectroscopic method, incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS), has been modified and extended to measure absorption spectra in the near-ultraviolet with high sensitivity. The near-ultraviolet region extends from 300 to 400 nm and is particularly important in tropospheric photochemistry; absorption of near-UV light can also be exploited for sensitive trace gas measurements of several key atmospheric constituents. In this work, several IBBCEAS instruments were developed to record reference spectra and to measure trace gas concentrations in the laboratory and field. An IBBCEAS instrument was coupled to a flow cell for measuring very weak absorption spectra between 335 and 375 nm. The instrument was validated against the literature absorption spectrum of SO2. Using the instrument, we report new absorption cross-sections of O3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably owing to the extremely weak absorption. The instrument was also applied to quantifying low concentrations of the short-lived radical, BrO, in the presence of strong absorption by Br2 and O3. A different IBBCEAS system was adapted to a 4 m3 atmosphere simulation chamber to record the absorption cross-sections of several low vapour pressure compounds, which are otherwise difficult to measure. Absorption cross-sections of benzaldehyde and the more volatile alkyl nitrites agree well with previous spectra; on this basis, the cross-sections of several nitrophenols are reported for the first time. In addition, the instrument was also used to study the optical properties of secondary organic aerosol formed following the photooxidation of isoprene. An extractive IBBCEAS instrument was developed for detecting HONO and NO2 and had a sensitivity of about 10-9 cm-1. This instrument participated in a major international intercomparison of HONO and NO2 measurements held in the EUPHORE simulation chamber in Valencia, Spain, and results from that campaign are also reported here.

Chemistry of B1- and B10- boranes containing halogen or pseudohalogen groups

The research described in this thesis involved the chemistry of borane-species which contain one or more halide or pseudohalide groups. Both monoboron species e.g. [BH3X]- and "cluster" borane species e.g. [B10H9X]2- and I-Se B11H10 were studied. The first chapter is a review of the syntheses, properties and reactions of halide and pseudohalide species containing from one to ten boron atoms. Chapter Two is a theoretical investigation of' the electronic and molecular structures of two series of boranes i. e. [BH3X]- and [B10H9X]2- where X = H, CI, CN, NCS, SCN and N3. The calculational method used was the Modified Neglect of Differential Overlap (MNDO) method of Dewar et al. The results were compared where possible with experimental results such as the X-ray crystallographically determined structures of [BH3CI]- and [B10H10]2-. Chapter Three concerns halogenated selenaborane clusters and reports an improved synthesis of 12-Br-SeB11H10 and the first structural data for a simple non-metal containing selenaborane cage with the X-ray crystallographically determined structure of 12-1-SeB11H10. Finally, an indepth n.m.r. study of Se2B9H9 is also reported together with attempts to halogenate this compound. The last two chapters are based on single boron systems. Chapter Four concerns the synthetic routes to amine-boranes and -cyanoboranes from [BH4]- and [BH3CN]- substrates. This chapter discusses some difficulties encountered when polyamines were used in these reactions. The characterisation of an unusual ketone isolated from some of these reactions, the X-ray crystallographically determined structure of 4-dimethylamino-pyridine-cyanoborane and a new route to pyrazabole dimeric species are also discussed. The final chapter reports on work carried out at producing BH2X (X = H, CN) adducts of aminophosphines. Three routes were attempted to generate P-B and N-B bonded species with varying degrees of success. Some unusual products of these reactions are discussed including [Ph2(O) PPPh2 ] [Ph2NH]2, the structure of which was determined by X-ray crystallography.

Precursor chemistry for oxide related materials

This thesis describes modelling, synthesis, spectroscopic and physical characterisation, as well as application of Magnesium, Calcium and Copper β-diketonate, β-ketoiminate, β-diiminate, Schiff base, amide and fluorenyl compounds. The selected compounds could potentially find application in materials deposition using Atomic Layer Deposition (ALD), MOCVD, CVD and Sol-Gel techniques. Quantum chemical modelling was used as a tool to perform the comprehensive and rapid study of magnesium and calcium precursor molecules in order to predict which of them would be more successful in ALD of metal oxides. Precursor chemistry plays a key role in ALD, since precursors must be volatile, thermally stable, chemisorb on the surface and react rapidly with existing surface groups. This Thesis describes one aspect of this, surface reactivity between ligands and hydroxyl groups, via a gas-phase model with energetics computed at the level of Density Functional Theory (DFT). A number of different synthetic strategies, both aerobic and anaerobic, were investigated for the synthesis of the described metal complexes. These included the use of different metal starting reagents such as, anhydrous and hydrated inorganic metal salts, metal alkyls and Grignard reagents. Some of previously unreported metal complexes of homoleptic and heteroleptic magnesium, calcium and copper β-diketonates, β-ketoiminates, β-diiminates, amides and Schiff base type were synthesised and characterised: [Mg(hfpd)2(DipPa)], [Mg(hfpd)2(MapH)2], [Mg(hf-ebp)(THF)2], [Mg(tf-Pap)Cl(THF)2], [Ca(PhNacnac)2], [Cu(tf-Pap)2], [Cu(PhNacnac)2], [Cu(hf-ebp)], [Cu(DipPa)] and [Cu(DipPa)2(4,4’-bypy)]. A comprehensive study on the thermal properties of magnesium, calcium and copper β-diketonates, β-ketoiminates, β-diiminates, Schiff base, amide and fluorenyl complexes was performed using TGA and sublimation of selected compounds. Atomic Layer Deposition of MgO using magnesium β-ketoiminate – [bis{(4-N-phenyl)-2-pentonato} magnesium] and β-diketonate - [bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)(THF)magnesium hydrate] was performed on Si(100) substrates at 180°C and 0.2 Torr using O2 plasma.