[en] This work aimed to compare two different catalysts in the production of a long chain ketone, intermediate in the production of hydrocarbons, during pyrolysis of tetradecanoic acid as a model fatty acid. The studied variables were the temperature, 450 and 600 deg C, and catalysts, γ-Al₂O₃ and Nb₂O₅, the latter has never been studied under such conditions. Pyrolysis experiments were performed in a micro-pyrolyzer coupled to a gas chromatograph with mass spectrometry detector (GC-MS). In all pyrolysis conditions, 14-heptacosanone was formed in varied amounts. Under the best conditions, for pyrolysis at 600 deg C, using γ-Al₂O₃ as catalyst, the yield of 14-heptacosanone was 18% and the yield of hydrocarbons 24%. The major hydrocarbon product obtained was 1-dodecene. Among the partially deoxygenated compounds, the main products were the ketones 14-heptacosanone and 2-pentadecanone. The present experimental work confirmed also the possibility to obtain hydrocarbons having a chain length longer than the chain length of the original fatty acid reagent, due to a ketonization route followed by decarbonylation. (author)

[en] Resonance Ionization-Mass spectrometry (RIMS) of atoms sputtered from solids has three main and well known advantages: high sensitivity, low interferences and freedom from matrix effects. With these unique features, RIMS is used to successfully characterize modern semiconductor devices which contain very thin films (<10 nm). For example, dopant tracking via depth profiling through ultra thin layers of materials is possible at the sub ppm level, thus assisting in device development and fundamental materials studies. RIMS is also used to investigae the effects of ion bombardment such as charging of samples, which may affect the transmission efficiency of resonantly generated ions and consequently the reproducibility of the instrument. Sample charging that induce voltage changes as small as 10 V during sputtering of GaAs can be monitored in real time via the Stark shift of Ga RIMS lines. Continuous and pulsed sputtering produce different voltage shifts under a variety of incident primary ion types, energies and doses. Charging semi-insulating GaAs is significant enough to deflect a 2 keV ion beam out of the analysis area in the ion source. High energy beams are not deflected as much even though the amount of charging is about the same

[en] The 50-mm superconducting dipole magnet approximately 1.3 m in length was fabricated at LBL to provide a background field up to 7 T in the Cable Test Facility at SSCL. The dipole has a stainless steel beam tube with a 47.88-mm OD and a wall thickness of 2.095 mm which significantly reduced the usefulness of this magnet. There were many unsuccessful attempts to remove this tube at 300 K and 80 K. The authors have devised a method of an ordinary multi-cutting process inside the magnet without its disassembly. In this article, tooling construction details with regulating cutting depths will be discussed

[en] A gamma ray tomograph design to reconstruct the catalyst concentration in an experimental riser was elaborated. An automated source/ riser/ detector arrangement, by means of a computational program, according to the defined irradiation parameters under the required mechanical precision, was projected. The data were obtained in an experimental arrangement in which the scanning was manually done. The basic parameters are gamma source intensity, beam diameter and source to detector distance. The criterion for parameter definition was the spectrum quality, quantified by the photopeak to total spectrum ratio and peak resolution. The ¹³⁷Cs nuclide is the source of major industrial riser applications, having only one gamma emission in an adequate energy (0.662 MeV) range. The geometry of the arrangement was formulated by the known equations of a solid angle between a punctual source and a detector. With the source and detector positioned on the same axis and source on a surface was also formulated. Arrangement conditions were specifically evaluated, such as the collimated gamma beam and its penetration through the aperture of detector collimator. The design and construction of adequate collimators was required mainly due to the important Compton scattering effects. Experimental data included source shape and position, resolution and efficiency related to beam diameter and gamma intensity reaching detector. The optimal scanning positions were studied by evaluating mathematical functions that reconstruct the catalyst concentration according to experimental conditions. The matrix of the data is obtained by a combination of parallel and angular dislocation, around riser, keeping source and detector on the same axis. The catalyst concentration measurement deals with a Beer-Lambert based equation in which the gamma intensities are for empty riser and flow conditions. Trying to reach such equation requirements, static experiments and simulated catalyst flow were carried out. The ¹³⁷Cs gamma source was of (3.7 x 10⁷ Bq.) or 10 mCi, a NaI 2^' x 2^' detector coupled to a multichannel analyzer positioned on the arrangement and the FCC catalyst in a stainless tube of 168 mm diameter. The tomograph design aims at the construction of a demonstration model with 1. 40 m of base height, maximum source detector distance of 0. 45 m and rotational angle of 50 deg, providing a spatial resolution of 5 mm and a density resolution of 40 kg/m³. (author)

No abstract available

[en] A cluster for parallel computation with MATLAB software the COCGT - Cluster for Optimizing Computing in Gamma ray Transmission methods, is implemented. The implementation correspond to creation of a local net of computers, facilities and configurations of software, as well as the accomplishment of cluster tests for determine and optimizing of performance in the data processing. The COCGT implementation was required by data computation from gamma transmission measurements applied to fluid dynamic and tomography reconstruction in a FCC-Fluid Catalytic Cracking cold pilot unity, and simulation data as well. As an initial test the determination of SVD - Singular Values Decomposition - of random matrix with dimension (n , n), n=1000, using the Girco's law modified, revealed that COCGT was faster in comparison to the literature [1] cluster, which is similar and operates at the same conditions. Solution of a system of linear equations provided a new test for the COCGT performance by processing a square matrix with n=10000, computing time was 27 s and for square matrix with n=12000, computation time was 45 s. For determination of the cluster behavior in relation to 'parfor' (parallel for-loop) and 'spmd' (single program multiple data), two codes were used containing those two commands and the same problem: determination of SVD of a square matrix with n= 1000. The execution of codes by means of COCGT proved: 1) for the code with 'parfor', the performance improved with the labs number from 1 to 8 labs; 2) for the code 'spmd', just 1 lab (core) was enough to process and give results in less than 1 s. In similar situation, with the difference that now the SVD will be determined from square matrix with n1500, for code with 'parfor', and n=7000, for code with 'spmd'. That results take to conclusions: 1) for the code with 'parfor', the behavior was the same already described above; 2) for code with 'spmd', the same besides having produced a larger performance, it supports a larger work load. (author)

[en] Cupuaçu husk (CH) is the waste of a common fruit from a native species of the Brazilian Legal Amazon. The current study investigated the influence of ultrasound (US) combined with aqueous, acid, alkaline, and ionic liquid (IL) pretreatments on the chemical and physical aspects of CH and the yield of chemical platforms production, 5-hydroxymethylfurfural (HMF) and furfural (FF), using IL. Scanning electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy were used to feature the raw and pretreated biomass. The highest levels of glucose (9.90 g L^-1) were observed in the liquid fraction resulting from the acid + US pretreatment followed by acid hydrolysis. The IL + US pretreatment recorded the best performance in removing lignin. Based on XRD analyses, ultrasound increased crystallinity of all pretreated samples as a result of the removal of cellulose's amorphous fraction. However, it promoted accessibility to adopted reagents by increasing biomass exposure due to cavitation. The best yields of HMF and FF were recorded from hydrolysis of the solid fraction resulting from the acid + US (12.94%) and alkaline + US (48.84%) pretreatment, respectively. These results indicate satisfactory performance of ultrasound assisted pretreatments to the simplified and economic conversion of biomass into value-added products. (author)

[en] The aim of this work is to investigate the corrosion behavior of powder metallurgy produced Nd-Fe-B magnets and to evaluate the corrosion protection afforded by two different surface treatments: a phosphate conversion and a non-functional silane (BTSE) layer. The electrochemical tests were performed in a phosphate buffered solution (PBS) at neutral pH, which ionic concentration coincides with that of the human body. The corrosion behavior was monitored by means of electrochemical impedance spectroscopy (EIS) and anodic potentiodynamic polarization curves, and SEM-EDS analyses were used to monitor coating deposition. EIS response has evidenced a porous electrode behavior for the Nd-Fe-B magnets according to the de Levie theory. The results also indicated a good performance of the phosphate layer, whereas the BTSE layer did not improve the corrosion resistance of the magnets. The good anticorrosion performance of the phosphate layer was explained on the basis of the formation of an insoluble phosphate layer both on the electrode surface (identified by interference colors) and on the pore walls. Precipitation of insoluble Nd phosphate on the Nd-rich phase also contributes to the superior corrosion protection afforded by this coating. (author)

No abstract available

[en] In the present work five acetylene derivatives (1-5), including three unknowns (1, 3 and 4), were isolated from seeds of Porcelia macrocarpa (Annonaceae). The structures of isolated compounds were determined as docos-13-yn-21-enoic acid (1), 3-hydroxy-4-methylene-2-(eicos-11'-yn19'-enyl)but-2-enolide (2), 3-hydroxy-4-methylene-2-(octadec-9'-yn-17'-enyl)but-2-enolide (3), 3-hydroxy-4-methylene-2-(hexadec-7'-yn-15'-enyl)but-2-enolide (4), and (2S, 3R, 4R)-3-hydroxy4-methyl-2-(eicos-11'-yn-19'-enyl)butanolide (5) by analysis of nuclear magnetic resonance (NMR) and electrospray ionization high-resolution mass spectrometry (ESI-HRMS) data. Moreover, all isolated compounds demonstrated selectivity towards intracellular amastigotes of Leishmania (L.) infantum, especially 2-4 with 50% inhibitory concentration (IC₅₀) values of 9.2, 10.4 and 11.0 μM, respectively, indicating superior activity of that determined to positive control miltefosine (IC₅₀ of 17.8 μM). Furthermore, these compounds showed higher selectivity index (SI) in comparison with miltefosine. Since related acetylene fatty acid 1 displayed reduced antiparasitic potential (IC₅₀ of 48.5 μM), the obtained results suggested that the γ-lactone plays an important role in the antileishmanial activity. However, 2-4 exhibited cytotoxicity to mammalian NCTC cells (CC₅₀ ca. 80 μM), which could be a result of the presence of a conjugated carbonyl system in the lactone ring, since 5, the only acetogenin that presents the saturated ring, lacked mammalian cytotoxicity (CC₅₀ > 200 μM). (author)