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The cutting and functionalization of carbon nanotubes is described, applying a single-step ball-mill based process. Very short carbon nanotubes bearing primary amine functions were produced, characterized and incorporated in polymeric membranes. The gas separation performance of the composite membranes was tested.

An efficient synthesis of the marine metabolite 3-bromoverongiaquinol (1) and the first total synthesis of 5-monobromocavernicolin (2), both isolated from the marine sponge Aplysina cavernicola, have been described based on the 1,2 addition of the lithium enolate of N,O-bistrimethylsilylacetamide (BSA, 4) to 1,4-benzoquinone (3). Bromination and purification of the crude product on silica gel chromatography provided 3-bromoverongiaquinol (1) in 50% overall yield. Under alkaline conditions, the crude product of the bromination reaction was converted to 5-monobromocavernicolin (2) in 20% yield which was also obtained in 13% yield (25% yield based on recovered starting material) from 3-bromoverongiaquinol (1).

Cu (I) phenyl acetylide was used as a source of copper to achieve a homogeneous distribution of Cu2O nanocrystals (10–80 nm) decorated on multiwalled carbon nanotubes (MWCNTs) having an average diameter of 10 nm. Pristine MWCNTs were first oxygen-functionalized by treating them with a mixture of concentrated (H2SO4/HNO3 : 3/1) acids and the products were characterized by X-ray powder diffraction, transmission and scanning electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy and thermogravimetric analysis. An easy, efficient and one-step impregnation method was followed to produce copper-containing nanoparticles on the MWCNTs. The copper-treated MWCNTs dried at room temperature were seen to be well decorated by copper-containing nanoparticles on their outer surface. The MWCNTs were then heat-treated at 400 °C in a nitrogen atmosphere to produce a homogeneous distribution of cuprous oxide nanocrystals on their surface. By varying the ratio of copper to oxygen-functionalized MWCNTs, Cu2O nanocrystals decorated on MWCNTs with different copper content can be obtained.

This paper presents the fundamental principles, instrumentation and selected applications of comprehensive two-dimensional gas chromatography (GC × GC). In this technique, introduced in 1991, two capillary columns are coupled and proper modulating interfaces continuously collect the eluate from the first column, transferring it to the second column. The result is a geometric increment in the chromatographic resolution, ensuring separation of extremely complex mixtures in time periods shorter or comparable to those of analysis using conventional gas chromatography and with better detectabilities and sensitivities.

A method to detect potential adulteration of commercial gasoline (Type C gasoline, available in Brazil and containing 25% (v/v) ethanol) is presented here. Comprehensive two-dimensional gas chromatography with flame ionization detection (GC × GC–FID) data and multivariate calibration (multi-way partial least squares regression, N-PLS) were combined to obtain regression models correlating the concentration of gasoline on samples from chromatographic data. Blends of gasoline and white spirit, kerosene and paint thinner (adopted as model adulterants) were used for calibration; the regression models were evaluated using samples of Type C gasoline spiked with these solvents, as well as with ethanol. The method was also checked with real samples collected from gas stations and analyzed using the official method. The root mean square error of prediction (RMSEP) for gasoline concentrations on test samples calculated using the regression model ranged from 3.3% (v/v) to 8.2% (v/v), depending on the composition of the blends; in addition, the results for the real samples agree with the official method. These observations suggest that GC × GC–FID and N-PLS can be an alternative for routine monitoring of fuel adulteration, as well as to solve several other similar analytical problems where mixtures should be detected and quantified as single species in complex samples.

In brazil, gasoline is usually adulterated by diesel oil, ethanol (in addition to the amount legally specified), petrochemical raffinates, and kerosene. This is an illegal action performed mainly in an attempt to raise profits. Therefore, methods for reliable identification of adulterated gasoline are very attractive. The aim of this work was to propose a method to quantify kerosene in gasoline through N-way multivariate analysis and a homemade Comprehensive Two-Dimensional Gas Chromatography with Flame Ionization Detection (GC × GC-FID). Models generated by Parallel Factor Analysis (PARAFAC), PARAFAC2, and Multi-way Partial Least Squares (N-PLS) allowed the quantification of kerosene in gasoline with Root Mean Square Error of Cross-Validation (RMSECV) values of 2.98%, 2.65%, and 2.08%, respectively.

Carbon nanotubes (CNT) are very promising nano-objects due to their exceptional properties. However, their tendency to form bundles as well as their insolubility in common solvents makes them difficult to handle. The main way to solve the problem is chemical or physical CNTs functionalisations, with all the problems inherent to the methods. In this contribution, we present a new approach that allows predicting the solubility of carbon nanotubes in many solvents but also predicting the most appropriate solvents to use for given samples of CNTs. Solubilisation and dispersion being directly connected, the present approach of solubilisation proves also to be efficient in dispersing the CNTs bundles. This contribution is a first step toward the control of carbon nanotube's dispersion in polymers and their homogenous functionalisation. Moreover, we also report here a new method, based on solvents, to separate carbon nanotubes by size, the use of mixture of non-solvents in order to obtain good solvents and the use of mixture of good solvents to obtain higher solubility. The use of mixture of good solvents allowed us to obtain high solubility, up to three times higher then that reported in literature. We have also measured and analysed the solubility of some functionalised carbon nanotubes.

Multi-walled carbon nanotubes functionalized with F3C-(CF2)5-(CH2)2-SiCl3, a molecule bearing a fluorinated terminal group is found to favor the carbon nanotubes dispersion in three perfluoropolyether fluids (Galden SV70, Fomblin Y25 and Fomblin YR1800). The stability of the suspension appears to be related to the perfluoropolyether viscosity. With respect to time, Fomblin YR1800, the more viscous fluid, leads to the most stable solutions, followed in order by Fomblin Y25 and Galden SV70. In general the smallest particles stay in suspensions. Stability extending over more than one year is observed in the case of Fomblin YR1800.

Multiwall carbon nanotubes have been grown on montmorillonite clay catalysts through anchoring on FeCo nanoparticles. The starting clay is a commercial sodium-rich montmorillonite in which the intercalated sodium ion was exchanged for cobalt(II) and iron(III) ions via mechanical agitation or sonication, both with and without subsequent centrifugation. The cobalt-iron intercalate clay was used as a catalyst for the synthesis of carbon nanotubes via decomposition of ethylene at 700 °C. The largest carbon deposit was obtained for catalysts prepared with 3 or 4 cation exchange equivalents. X-ray diffraction indicates both that the basal spacing of the clay increases from 12.43 A to 16.4 A upon intercalation of cobalt and iron. Atomic absorption analysis of the catalysts indicates that virtually all of the sodium ions originally present in the clay have been replaced by iron(III) and cobalt(II). Transmission electron micrographs show the presence of multiwall carbon nanotubes with inner and outer diameters of ca. 10 nm and 20 nm grown on metal particles present on the plates of catalysts. The iron-57 Mossbauer spectra indicate that the intercalated clay contains iron(III) in octahedral and tetrahedral sites and iron(II) in octahedral sites, the catalysts contain an extensive amount of small superparamagnetic particles of α-Fe2O3 and that the carbon-nanotube catalyst composites show the presence of iron(II) and iron(III) paramagnetic doublets, characteristic of a reduced montmorillonite, and of sextets that are characteristic of an FeCo alloy and of Fe3C cementite. The Mossbauer spectra indicate that the carbon nanotubes grow on FeCo metallic nanoparticles and bond to these particles through the formation of cementite.

This paper reports a 4.5 fold increase in the Young’s modulus of a semi-crystalline polymer, poly(vinyl alcohol), with the addition of carbon nanotubes. The importance of nanotube diameter is addressed with the production of four composite solutions with each solution containing carbon nanotubes of a specific diameter. Thin films were cast for tensile tests while Differential Scanning Calorimetry (DSC) measured the crystallinity of the composite material. Nanotubes were observed to increase polymer crystallinity such that the Young’s modulus of the composite also increased. Thus it is suggested here that in semi-crystalline polymer/nanotube systems, with non-covalent bonding between the filler and matrix, the formation of nanotube induced crystalline polymer domains is the dominant reinforcement mechanism and not stress transfer to the nanotube: the role of the nanotube lies in nucleating crystallization. In addition, the calorimetry data indicates that nanotube diameter and quality of dispersion determines the increase in crystallinity which in turn determines the mechanical properties of the composite. Furthermore, Transmission Electron Microscopy (TEM) images confirm an excellent dispersion and wetting of the various nanotube types in the polymer solution.

Localization of PdCl2 clusters supported on multi-wall carbon nanotubes (MWCNT) has been investigated using 129Xe NMR of adsorbed xenon. As-made MWCNTs with channels initially inaccessible for adsorption and ball-milled MWCNTs with the totally accessible internal surface were used as supports. The observed 129Xe NMR spectra were determined by the dynamics of xenon exchange between the aggregate pores and nanotube channels. No considerable changes of the 129Xe NMR spectrum with the concentration of supported PdCl2 were observed for the as-made MWCNT, while an additional resonance appeared for the ball-milled nanotubes. The 129Xe NMR experiments evidenced the supported species to be localized on the internal surface of the ball-milled MWCNT.

Multi-walled carbon nanotubes, chemically functionalized with 7-octenytrichlorosilane, are dispersed in one of the two reactive parts used to form a silicone elastomer. Links between the functionalized carbon nanotubes and the polymer matrix are created in situ during the curing step. Electrical and electrochemical properties of the silicone elastomer loaded with raw, purified, oxidized and functionalized carbon nanotubes are compared.

More than four boron per unit cell has been introduced into the framework of silicalite-1, using fluorine containing media. The initial gels were of composition 9MF–xH3BO3–10SiO2–1.25TPABr–330 H2O with M = NH4, Na, K and Cs and x = 0.1–10. The syntheses were carried out in hydrothermal conditions at 170°C. The amount of incorporated TPA+ ions remains quasi constant (3.5–3.8/u.c.) up to 4 B/u.c., while it decreases with increasing boron content. The amount of tetrahedral B/u.c. can be as high as 8 in presence of K+ or Cs+ ions in the as-synthesized samples. It is observed that the preferential countercations to framework negative charges related to the presence of tetrahedral boron, [SiOB]−, are TPA+, K+ and Cs+ ions. It is interpreted, that the −4.0 ppm versus BF3.OEt2 NMR line stems from tetrahedral framework boron, while the −2.9 ppm NMR line represents both extraframework and/or tetracoordinated deformed framework boron in the structure.

Rastreamento simultâneo de muitos objetos e necessario nos casos de investigacao do comportamento de organismos vivos, principalmente insetos [1]. Os metodos atuais apresentam dificuldades em registrar com precisao este tipo de comportamento e/ou sao de alto custo monetario[2-4]. O objetivo deste trabalho foi o de desenvolver um algoritmo e uma ferramenta computacional capaz de registrar com precisao o movimento simultâneo de dezenas de insetos. Foi desenvolvido um novo metodo a partir da combinacao de tecnicas de estimacao de fundo e iluminacao, operacoes de morfologia matematica e rastreamento usando criterio de minimizacao da distância global. No inicio e estimado o fundo estatico por meio da criacao de um modelo da iluminacao do ambiente com o uso de calculo da entropia local. O fundo estimado e subtraido do valor de luminância de todos os quadros do video. Apos uma limiarizacao das imagens, e aplicada uma serie de operacoes morfologicas com o objetivo de segmentar somente os insetos, e sao registrados os componentes conectados que representam os insetos. A posicao de cada elemento e registrada e a cada um determinado intervalo de tempo, a criterio do usuario, e calculada a trajetoria dos insetos. O algoritmo de rastreamento escolhe a configuracao que minimiza a distância global, ou seja, a soma de todas as trajetorias. O sistema proposto foi testado em setup de experimentos realizados no campo da biologia comportamental de insetos, especificamente, cupins. Foram utilizados videos de cupins em condicoes experimentais de iluminacao infravermelha. O movimento dos cupins registrado pelo sistema e diversos parâmetros foram calculados, entre numero total, numero de cupins entrando e saindo da arena, velocidade, tempo na arena, distância percorrida e tamanho dos cupins. A Figura 1 apresenta algumas destas medidas: (1a) o numero de cupins que entraram ou sairam da arena ao longo do tempo; (1b) a velocidade media dos cupins em a cada trecho de 10 segundos dos videos. Em ambas figuras sao apresentados resultados para dois videos em situacoes comportamentais diferentes, inicio e meio do experimento comportamental. Os resultados foram satisfatorios, correspondendo aos valores esperados e apresentando o nivel de precisao necessario para a area. Foi desenvolvida ainda uma intuitiva interface grafica para usuarios a fim de facilitar a operacao de usuarios nao especializados na area em computacao, com controle sobre diversos parâmetros da execucao (Fig. 2). Os resultados como um todo sugerem que o novo sistema auxiliara pesquisadores no registro de comportamento animal e resultara em uma grande economia em tempo de registro manual [...]

The focus of this chapter is the application of multiway calibration with GC × GC data. The amount of information contained on a GC × GC chromatogram is considerably larger, which causes manual interpretation of a data set into a very difficult task (or, in many cases, virtually impossible), especially for complex samples. Two basic categories for multiway calibration have been used in data from 2D separations: a two-step approach, where chemometric deconvolution techniques are first applied and then a univariate calibration model is developed, and a direct approach, where multivariate calibration models are directly generated from the data set. Algorithms and applications of both strategies are presented in this chapter.

MCM-22 or MCM-49 zeolites were directly prepared using NaOH or KOH as mineralizing agents. The initial batch composition was 30SiO 2 – v Al(OH) 3 – x NaOH(or x KOH)– y HMI– z H 2 O, with v = 1, 1.5, 2, 3; x = 2.7, 5.4, 9, 10.5, 12, 15, 18; y = 10.6, 15; z = 1050, 1200, 1350; HMI = hexamethyleneimine. The products were obtained by hydrothermal synthesis at 150 °C in stirring conditions. For HMI/Na ratio greater than 2 MCM-22(P) is formed, while for a lower HMI/Na ratio MCM-49 is formed. In presence of K + ions only MCM-22(P) could be obtained. In addition, the Al content of the MCM-22(P) samples is much lower (ca. 10 mol%) than those obtained with Na + ions (ca. 20 mol%). The MCM-22(P) zeolites prepared in presence of Na + ions are formed much faster than those prepared in presence of K + ions. The formation of MCM-22(P) is more difficult with increasing Al-content in the gel. The 27 Al NMR spectra show two lines at 55.5 ppm and 49.9 ppm. Both are due to framework tetrahedral species. No extraframework octahedral species were detected in any of the samples. The 29 Si NMR spectra could be decomposed using eight crystallographically different sites.

Significant increases in the Young's modulus of nanotube–polymer composites have been associated with the formation of an ordered polymer layer coating the nanotubes. Polyvinyl alcohol (PVA) is known to display nanotube-induced ordering. It is used here as a model matrix to investigate how the polymer coating influences the mechanical reinforcement of the composite material. Young's modulus and calorimetry measurements were carried out on films of PVA-based composites reinforced with different types of nanotubes. An unmistakable correlation between polymer ordering and reinforcement was found. This is supported by the introduction of a model capable of establishing, on quantitative grounds, how the ordered phase affects the increase in the Young's modulus. Rather than acting as intrinsically stiffer reinforcing agents, our results suggest that the major role played by the nanotubes in improving the mechanical properties of composites is to nucleate an ordered polymer coating. It is the presence of this stiff ordered phase that dominates the reinforcement mechanism.

Carbon nanotubes with the Stone-Wales defects were generated, and molecular dynamics simulations of the nanotubes have been performed at temperature of 300 K using the reactive empirical bond order potential and Lennard–Jones one. The carbon configurations obtained from the simulations were used to calculate the powder diffraction patterns, which have been converted to a real space representation, yielding a pair correlation function. The theoretical results are compared with the pulsed neutrons experimental data for the carbon nanotubes synthesised by catalytic chemical vapour deposition. These comparisons show important influence of the Stone-Wales defects on the simulated results and their best agreement with the experimental data is obtained for 0.87% concentration of the defects.

Organic polymers - carbon nanotubes nanocomposites are synthesized either by mechanical mixing of the two components or by covalently linking the nanotubes to the matrix. The various procedures will be overviewed and the determining factors will be identified for the best mechanical properties of the composites. On the other hand, it will be shown that for highest electrical conductivity much smaller amounts of carbon nanotubes are needed if the nanotubes can be aligned. The thermal conductivity of the nanocomposites will also be overviewed. Finally, together with nanoclay particles, nanotubes are inducing remarkable flame retardant properties in the nanocomposites materials.

Carbon nanotubes (CNTs) currently attract intense research efforts because of their unique properties which make them suitable for many industrial applications. When inhaled, CNTs constitute a possible hazard to human health. Several studies have shown that when instilled in the lung of experimental animals, CNTs induced an inflammatory and fibrotic response similar to that caused by other toxic particles which might be the result of oxidative stress caused by particle- and/or cell-derived free radicals. There is, however, no direct experimental evidence of a capacity of carbon nanotubes to generate directly free radicals. Here we report that multiwall carbon nanotubes (MWCNT) in aqueous suspension do not generate oxygen or carbon-centered free radicals in the presence of H2O2 or formate, respectively, as detected with the spin-trapping technique. Conversely, we observed that, when in contact with an external source of hydroxyl or superoxide radicals, MWCNT exhibit a remarkable radical scavenging capacity. It is therefore possible that the inflammatory reaction reported in vivo must be ascribed to MWCNT features other than particle-derived free radical generation.

Carbon nanotubes containing non-hexagonal rings have been computer generated and relaxed by minimization of the energy using the conjugate–gradient method. Then the powder diffraction patterns have been computed and converted to a real-space representation by the Fourier transform, yielding pair correlation functions which are compared with the pulsed neutrons experimental data for the single-wall carbon nanotubes produced by catalytic chemical vapour deposition. Effects of defective graphene cylinders on the interatomic distances and the resulting structures are discussed. The obtained results are also discussed in relation to previously reported paracrystalline behaviour of the nearest-neighbours distance fluctuations.

Carbon nanotubes focus the attention of many scientists because of their huge potential of industrial applications, but there is a paucity of information on the toxicological properties of this material. The aim of this experimental study was to characterize the biological reactivity of purified multi-wall carbon nanotubes in the rat lung and in vitro. Multi-wall carbon nanotubes (CNT) or ground CNT were administered intratracheally (0.5, 2 or 5 mg) to Sprague-Dawley rats and we estimated lung persistence, inflammation and fibrosis biochemically and histologically. CNT and ground CNT were still present in the lung after 60 days (80% and 40% of the lowest dose) and both induced inflammatory and fibrotic reactions. At 2 months, pulmonary lesions induced by CNT were characterized by the formation of collagen-rich granulomas protruding in the bronchial lumen, in association with alveolitis in the surrounding tissues. These lesions were caused by the accumulation of large CNT agglomerates in the airways. Ground CNT were better dispersed in the lung parenchyma and also induced inflammatory and fibrotic responses. Both CNT and ground CNT stimulated the production of TNF-alpha in the lung of treated animals. In vitro, ground CNT induced the overproduction of TNF-alpha by macrophages. These results suggest that carbon nanotubes are potentially toxic to humans and that strict industrial hygiene measures should to be taken to limit exposure during their manipulation.

The statistical distribution of a large number of helically coiled carbon nanotubes was analyzed in a cross-correlated way in their geometrical configuration space defined by diameter and pitch. Stability islands were identified, in which the number of coils exceeds about 15–10 times the value corresponding to a uniform distribution. When comparing our data with data from literature, a good agreement is found. The statistical findings are interpreted as indirect evidence that the geometric configuration of coiled carbon nanotubes is rather decided by the atomic structure of carbon layers building up the coils than by the external parameters which on the other hand may induce the particular conditions under which coiling occurs. The possible effect of impurities like N and S on the incorporation of non-hexagonal rings and tubular growth is pointed out.

Helical carbon nanotubes were produced on silica-supported Co catalysts by chemical vapour decomposition of acetylene. Coiled nanotubes were examined. They have been found to be of various shapes, diameter, and pitch. Some of them are extremely long, up to 5 mu m, with regular helices. The average outer diameter of coils are about 30-50 nm, the pitch is in the range 50-200 nm and the length about 1- 1.4 mu m. The helix-shaped windings of the helical carbon nanotubes reveal characteristic mechanical resonances, which are determined by the elastic modulus, mass, shape, and dimensions.

In this paper we demonstrate the functionalization of single-walled carbon nanotubes prepared by chemical vapor deposition. The chosen functionalization agents were alkyl-halides such as trifluoromethane (TFM) and trichloromethane (TCM); or double bond containing alkyl-halides as tetrachloroethylene (TCE) and hexafluoropropene (HFP) that can easily form radicals. Functionalization of samples was carried out under mild conditions, by ball milling of nanotubes in an atmosphere of functionalization agent, at room temperature. For the sake of comparison, chlorination was also performed by chlorine gas. In this process the cleavage of nanotube C–C bonds results in active sites, which can activate molecules in gas phase or adsorbed on the surface of carbon nanotubes. Halogenated samples were characterized by means of particle induced γ-ray emission, transmission electron microscopy, thermogravimetry, and X-ray photoelectron spectroscopy. We concluded that this method gives functionalized single-walled carbon nanotubes in the range of 0.3–3.5 wt.% of fluorine and 5.5–17.5 wt.% of chlorine.

We report on the controllable growth of individual, uniform carbon nanotubes using thermal chemical vapor deposition (CVD). We performed a detailed study of the various factors influencing the growth of single nanotubes. In particular, we investigated the role played by catalyst layer thickness, catalyst dot size, deposition temperature, and gas source pressure on the growth process of straight, single nanotubes. Straight, individual nanotubes with uniform diameter can be obtained by decomposition of 0.1 mbar of acetylene at a temperature of 800 °C over a 5 nm thick nickel film that is patterned into square dots with dimensions below 500 nm. We compare the performance of thermal CVD and of plasma enhanced CVD for growing individual nanotubes.

Multiwall carbon nanotubes containing carbon–zeolite composite materials have been obtained by ethylene catalytic chemical vapor deposition (CCVD) on Co-modified beta zeolite powder. High carbon selectivity to nanotubes was achieved. The combined physical characterisation through several techniques, such as TEM, HRTEM, SEM, XRD, N2 adsorption–desorption, allows to determine the geometric characteristics of nanotubes and their dependence of catalyst and synthesis conditions.

DISTRIBUIÇÃO DO VOLUME DE ÁGUA APLICADO PELO MICROASPERSOR DAN 2001 Marco Antônio Fonseca Conceição1; Rubens Duarte Coelho21Empresa Brasileira de Pesquisa Agropecuária, Uva e Vinho,Estação Experimental de Viticultura Tropical, Jales, São Paulo, marcoafc@cnpuv.embrapa.br2Departamento de Engenharia Rural, Escola Superior de Agricultura “ Luiz de Queiroz”, Universidade de São Paulo 1 RESUMO Na irrigação por microaspersão deve-se conhecer a distribuição do volume de água aplicado pelos emissores, a fim de se realizar um manejo eficiente do sistema. O objetivo do presente estudo foi determinar a distribuição radial do volume de água aplicada por microaspersores autocompensantes que utilizam rotores. As avaliações experimentais foram realizadas no laboratório de irrigação do Departamento de Engenharia Rural (DER) da ESALQ/USP em Piracicaba, SP. Foram empregados microaspersores DAN 2001 com rotores preto (bocais violeta, cinza e marrom) e azul (bocais azul, verde, laranja e amarelo). Os maiores percentuais dos volumes de água aplicados ficaram entre as distâncias de 1,2 m e 1,8 m, para os bocais violeta, cinza e marrom; entre 1,8 m e 2,4 m para o bocal azul; e entre 2,4 m e 3,0 m, para os bocais verde, laranja e amarelo. UNITERMOS: Distribuição de água, eficiência de irrigação, irrigação localizada. CONCEIÇÃO, M. A. F; COELHO, R. D. WATER VOLUME DISTRIBUTION USING DAN 2001 MICROSPRINKLERS 2 ABSTRACT In microprinkler irrigation it is necessary to know the water volume distribution to implement an efficient system management. The purpose of the present study was to determine the radial water volume distribution applied by pressure compensating microsprinklers with swivels. Experimental evaluations were carried out at the irrigation laboratory of the Dept. of Rural Engineering/ESALQ/USP,Piracicaba, SP. Dan 2001 microsprinklers with black swivel (violet, gray and brown nozzles) and blue swivel (blue, green, orange and yellow nozzles) were used. The largest applied water volumes were verified at the distance of 1.2 m to 1.8 m from the emitter, for violet, gray and brown nozzles; 1.8 m to 2.4 m for blue nozzle; and 2.4 m to 3.0 m for green, orange and yellow nozzles. KEYWORDS: Irrigation efficiency, Microirrigation, Water distribution.

In this study, a new type of materials, based on ethylene–vinyl acetate (EVA) copolymers, commercial organo-modified clays (organoclays) and multi-walled carbon nanotubes (MWNTs) has been prepared via direct melt blending. Both crude and purified MWNTs have been investigated. Thermal, flame retardant and tensile properties of the resulting new ternary nanocomposites have been measured and compared to the corresponding binary systems, i.e., EVA filled with either clays or carbon nanotubes. This new family of composites exhibits enhanced properties even at very low filler level usually inferior to 5 wt%. Interestingly, a synergistic effect arising from the combination of MWNTs and organoclays has been evidenced in some cases.

Carbon nanotubes were synthesised within the pores of an alumina membrane. The membrane had 200 nm diameter pores and 60 microm thickness, and ethylene was used as carbon source. Membrane dissolution by HF results in a bundle of parallel open tubes, aligned without macroscopic defects. The external diameter of the tubes is uniform and there is no evidence of any amorphous carbon. Wall thickness control was obtained by varying the reaction time, length by the thickness of alumina membrane, and external tube diameter by the membrane pore size. Scanning (SEM) and transmission (TEM) electron microscopy, atomic force microscopy (AFM), X-ray diffraction, thermogravimetric analysis (TG) and surface area evaluation by nitrogen adsorption were used for the characterization of membrane and nanotubes.

Iron and molybdenum containing sol–gel catalysts were prepared using various methods, i.e. different solvents, metal salts and different drying processes – including the application of chelating agent or freeze-drying – and investigated in the synthesis of single wall carbon nanotubes. The quality and quantity of the product proved to be very sensitive to the synthesis parameters and also to the composition and preparation way of the catalyst. It was demonstrated that there is no significant correlation between the catalytic activity and the specific surface area, while the texture of the catalyst influenced by the preparation way is a much more important factor.

After adsorption on a silicon substrate, coiled multiwalled nanotubes retain a 3D structure with sections of freely suspended windings. Electrical gold contacts attached to the nanotubes turn out to be sensitive to vibrations (i.e., the contacts reveal a piezoresistive-like response). When exciting the nanotube windings either electrically or acoustically, the fundamental resonances (ranging from 100 to 400 MHz) can be detected. The resonators are sensitive to mass changes as small as a few tens of attograms.

Four complementary and independent methods are used to characterize nanotube samples: (i) TEM observation coupled with image analysis, (ii) nitrogen and krypton adsorption isotherm analysis, (iii) thermogravimetry and (iv) wide angle X-ray scattering. The methodology is discussed on the basis of two multi-walled carbon nanotube samples produced by the CCVD technique with very different reaction rates. It is shown that the total amount of deposited carbon is larger for the sample produced at the higher rate, that the fraction of nanotubes in the deposited carbon does not seem to be significantly different, but that the crystallinity of the nanotubes wall is larger for the sample produced at the lowest reaction rate.

In this paper, the chemical functionalization of multi-walled carbon nanotubes by a fluorinated trichlorosilane ((tridecafluoro-1,1,2,2-tetrahydrooctyl)trichlorosilane) is investigated. The chlorosilane has been shown to react with carboxylic acid moieties, created by an oxidative process on the nanotube walls, as well as with alcohol groups obtained by a reductive reaction of these previous oxidized nanotubes. The derivatizations were directly confirmed by x-ray photoelectron spectroscopy and thermogravimetry analyses. Little difference in the functionalization was observed for the oxidized or reduced nanotubes. However, the amount of grafted silane seems to be slightly more important when the silanization is carried out with reduced nanotubes.

EFEITO DO VENTO SOBRE A DISTRIBUIÇÃO DE ÁGUA PORMICROASPERSORES DAN 2001 Marco Antônio Fonseca Conceição1; Rubens Duarte Coelho21Estação Experimental de Viticultura Tropical, Empresa Brasileira de Pesquisa Agropecuária - Uva e Vinho, Jales, SP, marcoafc@cnpuv.embrapa.br2Departamento de Engenharia Rural, Escola Superior de Agricultura, Universidade de São Paulo, Piracicaba, SP. 1 RESUMO A ocorrência de ventos pode modificar a distribuição da água aplicada por microaspersores, comprometendo a eficiência e a uniformidade de aplicação. O presente trabalho teve como objetivo avaliar a distribuição de água aplicada por microaspersores operando sob condição de vento, comparando-a com a distribuição sem vento. As avaliações experimentais foram realizadas em condições de laboratório empregando-se microaspersores da marca DAN 2001, com diâmetros de bocais iguais a 0,84 mm (violeta), 1,00 mm (cinza), 1,10 mm (marrom), 1,25 mm (azul), 1,33 mm (verde), 1,48 mm (laranja) e 1,75 mm (amarelo). Os bocais violeta, cinza e marrom trabalharam com rotor preto e os demais bocais trabalharam com rotor azul. O efeito do vento foi provocado artificialmente empregando-se um conjunto de quatorze ventiladores de 200 W de potência e 0,50 m de diâmetro interno. As áreas molhadas e os volumes coletados em condições de vento foram inferiores aos obtidos na ausência de vento, enquanto que as intensidades médias de precipitação com vento foram superiores às sem vento. UNITERMOS: eficiência de aplicação, irrigação, microaspersão. CONCEIÇÃO, M. A. F.; COELHO, R. D. WIND EFFECT ON WATER DISTRIBUTION USING MICROSPRINKLERS 2 ABSTRACT Wind occurrence can modify water distribution using micro sprinklers, reducing application efficiency and uniformity. The present work had as a general objective to evaluate the water distribution using micro sprinklers under windy condition. Experimental tests were carried out in laboratory using DAN 2001 micro sprinklers with nozzle sizes of 0.84 mm (violet), 1.00 mm (gray), 1.10 mm (brown), 1.25 mm (blue), 1.33 mm (green), 1.48 mm (orange) and 1.75 mm (yellow). The violet, gray and brown nozzles operated using black spin and the others used blue spin. The wind effect was artificially simulated using fourteen fans (200 W power). Windy wetted areas and collected volumes were smaller than those obtained in windless conditions, whereas the average precipitation intensities were higher than those without wind. KEY WORDS: application efficiency, irrigation, micro irrigation.

This paper reports on structural characterisation of single and multi-wall carbon nanotubes, synthesised by catalytic decomposition of methane and acetylene, by wide-angle pulsed neutron scattering, extended up to a maximum scattering vector of Qmax=60 A−1. The intensity data were converted to real space via the Fourier transform yielding the radial distribution functions (RDFs) with the resolution of approximately 0.1 A. The structural parameters defining the interatomic distances, their standard deviations and the coordination numbers have been derived from the experimental data by a curve-fitting method based on a least-squares algorithm. The nearest-neighbour carbon–carbon distance 1.41 A is practically the same as that of graphite and clearly shorter than the value of 1.44 A found for fullerenes. The results provide experimental evidence for the hexagonal structure within a single tubule and turbostratic stacking of successive tubules. The derived RDFs can be fitted using a model based on a hexagonal network with disorder increasing with square root of the interatomic distance.

RELAÇÃO VAZÃO x PRESSÃO EM MICROASPERSORES DAN 2001 SOB CONDIÇÃO ADVERSA DE OPERAÇÃO Marco Antônio Fonseca ConceiçãoEmbrapa Uva e Vinho, Estação Experimental de Jales, Jales, SP. CP 241. CEP 15700-000.E-mail: marcoafc@cnpuv.embrapa.brRubens Duarte CoelhoDepartamento de Engenharia Rural, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, SP. CP 09, CEP 13418-900.E-mail: rdcoelho@esalq.usp.br 1 RESUMO Alguns microaspersores possuem membranas que regulam a sua pressão de operação, mantendo a vazão praticamente estável dentro de uma faixa de pressão na rede hidráulica. Operadores de irrigação no campo, muitas vezes com baixo nível de instrução e sem orientação profissional qualificada, visando reduzir problemas de entupimento ou para diminuir o tempo de irrigação, costumam retirar as membranas autocompensantes para aumentar a vazão do emissores, o que pode comprometer o desempenho hidráulico do sistema. Para avaliar o efeito da retirada da membrana sobre as vazões dos microaspersores, no presente trabalho determinou-se as relações entre pressão e vazão para sete bocais do microaspersor DAN 2001, operando na ausência da membrana autocompensante. As curvas pressão-vazão sem as membranas autocompensantes apresentaram comportamento potencial com expoentes variando entre 0,58 e 0,64. As vazões dos microaspersores sem as membranas aumentaram de forma inversamente proporcional aos diâmetros dos emissores, quando comparadas às vazões nominais com as membranas. UNITERMOS: Hidráulica, irrigação, microaspersão. CONCEIÇÃO, M.A.F.; COELHO, R.D. FLOW X PRESSURE RELATIONSHIP FOR DAN 2001 MICROSPRINKLERS UNDER ADVERSE CONDITION 2 ABSTRACT Many types of microsprinklers have a self-compensating membrane to regulate their pressure, keeping a stable flow. Many producers usually take the membranes off to reduce clogging problems or irrigation time. This procedure could endanger the system hydraulic performance. To evaluate the effect of taking off the self-compensating membrane from microsprinklers it was determined, in the present work, the pressure-flow relationship for seven Dan 2001 microsprinkler nozzles operating without the membrane. The pressure-flow curves presented a potential behavior with the exponents varying from 0.58 to 0.64. Microsprinkler flows without the membranes increased inversely proportional to the emitter diameters, comparing to the nominal flows using the membranes. KEYWORDS: Hydraulic, irrigation, microsprinkler.

The Petrobras management of safety, environment and health introduces in this paper its new strategy to reduce emissions, residues, effluents and to improve the prevention and control of accidents in all its units. With expected investments of more than US$ 1 billion from 2000 to 2003 the Program for Excellence in Environmental and Operational Safety Management is Petrobras’ strategy for becoming one of the best petroleum companies of the world, regarding safety and environmental protection.

Chemical and structural modifications induced by protons at the surface of polyacrylonitrile and carbon nanotube/polyacrylonitrile composite films are analysed by TEM, profilometry, IR and XPS. Changes induced in the film are related to the energy of incident particle and implanted dose. The irradiation of the composite films induces the emergence of the nanotubes outside of the polymer but with no increase of the surface roughness. Spectroscopic modifications in both films are globally similar, the most significant feature being a lower relative concentration of nitrogen with respect to carbon close to the surface.

A simple mechano-chemical modification of multiwall carbon nanotubes is described. The use of ball-milling in specific atmosphere allows us to introduce functional groups like thiol, amine, amide, carbonyl, chlorine, etc. onto carbon nanotubes. The resulted functional groups are characterized using infrared spectroscopy and X-ray photoelectron spectroscopy.

Single- and multi-wall carbon nanotubes synthesized by catalytic decomposition of methane and acetylene, respectively were studied for their hydrogen adsorption capacity in their hollow and on their outer surface. The hydrogen storage capacity of the samples was measured for pressures 0-9 bar at 295 K and at 77 K. The results at different temperatures on the crude sample (closed tubes 10-50 μm long), on the purified sample (open tubes 10-50 μm long) and on the purified and broken sample (open tubes 0.1-0.7 μm long) show that breaking the nanotubes allows one to adsorb hydrogen in their hollow. In addition, the relative amounts of hydrogen adsorbed in the hollow and outer parts of the nanotubes can be distinguished.

MgO-supported catalysts are used to produce high yield carbon nanotubes with few walls by the catalytic decomposition of acetylene. Low and high resolution transmission electron microscopy (TEM and HRTEM, respectively) reveals that the tubes possess many irregularities in their wall structure and that they appear as aggregates. The outer diameter of the multi-wall carbon nanotubes (MWNTs) obtained by this procedure is in the order of 5–10 nm while the inner diameter is less than 4 nm. Their resistance strongly depends on the post-synthetic treatments made upon them. Raw material obtained after synthesis is insensitive to ball-milling and tubes remain packed. The same feature appears after grinding the sample, treated with a concentrated acid in order to remove the support and the catalytic metal particles. The easy breaking of the tubes occurs after specific treatment of the sample.

Catalytic activity of iron, cobalt and a mixture of iron and cobalt supported on Al 2 O 3 and SiO 2 has been investigated in the production of carbon nanotubes (NTs). The supports are obtained from different methods. Acetylene was used as the source of carbon and nitrogen as the carrier gas. The pyrolysis of hydrocarbon was carried out at 500, 600 and 700 °C. The effect of other reaction parameters such as rate of flow of the hydrocarbon, carrier gas and the reaction time has also been investigated. Transmission electron microscope (TEM) was used to follow the quality and nature of NTs formed. It was observed that a good quality and quantity of multiwall carbon nanotubes (MWNTs) were produced when alumina prepared from aluminum isopropoxide and deposited with a mixture of iron and cobalt catalysts was used.

Carbon nanofibers with high surface area can be synthesized in a simple one-step reaction under relatively mild conditions using unsupported SnO-doped Fe 3 C catalyst. The highest activity and carbon fibers with high surface area were obtained with catalyst prepared by direct precipitation. Over this sample, selectivity of carbon deposit formation was close to 100%. It was concluded that the interaction of the two phases might be responsible for the catalytic activity, while the method of dispersal seemed to be important for the quality and surface area of the carbon deposit.

Multiwall carbon nanotubes grown by the catalytic decomposition of acetylene over supported Co catalyst were subjected to wet and dry oxidation in order to remove the unwanted products and the catalyst traces. The effects of the purification treatment on the Co content Ž. Ž . was monitored by physical methods: Rutherford Backscattering Spectrometry RBS , Particle Induced X-Ray Emission PIXE and Ž. X-Ray Fluorescence XRF . The purified products were investigated by microscopic methods: TEM, Scanning Electron Microscopy Ž. Ž . SEM , Energy Dispersive Spectroscopy EDS and STM. The KMnOrH SO aqueous oxidation procedure was found to be effective in 42 4 reducing the Co content while damaging only moderately the outer wall of the nanotubes. Treatment in HNO rH SO yields a 32 4 bucky-paper like product and produces the increase of the Si and S content of the sample. q 2002 Elsevier Science B.V. All rights reserved.

This paper aims at presenting an application developed in Java for optimizing the design of centralized solar water heating systems with forced circulation, based on the f-chart method. The program uses data from the Brazilian Solar Atlas, performance data of flat plate collectors and thermal reservoirs from the standardized tests run within the Brazilian Labeling Program, and values of water consumption of appliances defined by the ABNT. The program finds the inclination of the collector that maximizes the annual solar fraction, or for the winter, and enables the use of arrays in series and parallel collectors. From the investment costs and O & M (operations and maintenance) of solar heating systems, the program carries out economical analysis using classical parameters as net present value, discounted payback and internal rate of return. The program was validated through examples from the book of Duffie & Beckman and also by comparison with the results from a project developed at UFRGS, having obtained good agreement.

We introduce a method for atomic force microscopy (AFM)-based detection of mechanical resonances in helix-shaped multi-walled carbon nanotubes. After deposition on an oxidized silicon substrate, the three-dimensional structure of suspended nanotubes, which bridges an artificially created step on the surface, can be visualized using AFM operating in the non-contact mode. The suspended coiled nanotubes are resonantly excited, in situ, at the fundamental frequency by an ultrasonic transducer connected to the substrate. When the AFM tip is positioned above the coiled nanotube, the cantilever is unable to follow the fast nanotube oscillations. Nevertheless, an oscillation amplitude-dependent signal is generated due to the non-linear force-to-distance dependence. Measurement of the mechanical resonances of the helix-shaped carbon nanotubes can be used to quantitatively determine their elastic properties. Assuming that a coiled nanotube can be modeled as a suspended helix-shaped uniformly thin elastic beam, the obtained resonance frequency is consistent with a Young’s modulus of 0.17±0.05 TPa.

Catalytic synthesis and physicochemical characterization of multi- and single-wall carbon nanotubes are presented. Supported transition metal(s) catalysts were prepared by different methods and were tested in the production of nanotubes by decomposition of hydrocarbons at 700 and at 1000 °C, using a fixed bed flow reactor. The carbon deposits were measured and the quality of the nanotubes was characterized by transmission electron microscopy. The inner and outer diameters of the nanotubes were also measured and the diameters distribution histograms were established : Thick multi-wall straight and coiled nanotubes with inner diameters (minimum-[average]-maximum) of 4-[6]-10 nm, outer diameters of 8-[25]-50 nm and with lengths up to 50 mm. Thin multi-wall straight and coiled nanotubes with inner diameters of 3-[4]-7 nm, outer diameters of 5-[15]-25 nm and with lengths up to 50 mm. Very thin multi-wall straight and coiled nanotubes with inner diameters of 2-[4]-7 nm, outer diameters of 3-[10]-15 nm and with lengths up to 50 mm. Single-wall nanotubes isolated or as bundles with diameters of 1-[2]-4 nm and with lengths up to 1 mm. The influence of various parameters such as the way of catalyst preparation, the nature and the pore size of the support, the nature of the metal(s), the quantity of catalyst active particles and the reaction conditions on the nanotubes formation were studied.