Obtenção de um material adsorvente para íons de metais pesados, através da eletropolimerização de 2-mercaptobenzimidazol à superfície de carbono vítreo reticulado

Electrochemical methods applied to organic species transformation has been used as excellent synthesis tools. C-C bonds can be established, making possible polymer synthesis by both anodic and cathodic reactions of suitable monomer species at the working electrode surface. In this study, anodic procedure was used to electropolymerization of 2-mercaptobenzimidazole at reticulated glassy carbon (RGC) surface. 2-mercaptobenzimidazole presents ligand sites towards Hg2+, Ag+ and Cu2+ ions. The obtained material has been able to adsorb the above mentioned ions in aqueous solution.

Ager Tarraconensis 5. Paisatge, poblament, cultura material i història = Landscape, Settlement, Material Culture and History Proceedings of the International Symposium

Aquesta obra recull 28 comunicacions presentades al Simposi internacional «L’ager Tarraconensis. Paisatge, poblament, cultura material i història», celebrat a Tarragona el 27 i 28 d’octubre del 2010, organitzat per l’Institut Català d’Arqueologia Clàssica a la seu de l’Institut i a la Diputació de Tarragona. Les aportacions al simposi se centren en l'evolució del paisatge al Camp de Tarragona i en altres regions del món romà, en la varietat de les primeres estratègies de control romà del territori, en les tipologies i evolució dels establiments, en aspectes econòmics i en la dinàmica del poblament, sense faltar-hi alguna aportació de l'epigrafia. Tot plegat fa referència molt especialment al territori de Tarraco, tot i que el simposi també va comptar amb comunicacions sobre altres territoris de l'àrea catalana i saguntina i d'altres províncies romanes, com la Lusitània, les Gàl·lies i la Transpadana; les comparacions entre diferents regions han donat una riquesa notable al debat. Entre els resultats més suggerents comptem amb la constatació de la similitud en els models de romanització del territori en les diferents àrees d'àmbit català i valencià, que contrasten significativament amb els models de territoris d'Andalusia, França i Portugal.

Els Gèneres de la narrativa oral en prosa: material didàctic d’aula ordinària d’ESO amb presència d’alumat que té el català com a segona llengua

En aquest treball proposem crear materials didàctics per a l’alumnat de les aules de secundària que en molts casos és heterogeni i inclou estudiants que surten de l’aula d’acollida amb un coneixement del català informal i que tenen dificultats per a incorporar-se al ritme habitual de l’aula ordinària

Estudi per a la implantació d'un ERP en una empresa de fabricació de material per a minusvàlids

Un sistema ERP és una aplicació que ens permet fer la gestió dels processos de negoci de una forma àgil. Aquest projecte tracta sobre l’estudi per a la implantació d’un ERP en una empresa de fabricació de material per a minusvàlids. Inicialment es farà una part teòrica sobre el que són els sistemes ERP. A continuació, s’analitza el funcionament de l’empresa on es realitzarà l’estudi. Finalment, s’estudien tres solucions ERP del mercat actual i es selecciona la que millor s’adapta a les necessitats i requeriments en vistes a una possible implantació.

Dissulfeto de molibdênio, um material multifuncional e surpreendente

The aim of this work is to review the chemical and physical properties of layered molybdenum disulfide. The three polymorphic/polytypic modifications of the compound were found, the polytypes 2H (molybdenite) and 3R are semiconductors while the polymorph 1T is an electronic conductor. 2H-MoS2 has several important industrial applications as hydrotreatment catalysts, energy storage devices, solar cells, solid lubricants, among others. When intercalated, the 2H phase changes to a distorted 1T phase, producing unstable intercalation compounds that can be exfoliated in solution, producing single layers and consequently nanocomposites. The direct synthesis of the 1T phase produces stable intercalation compounds. Recently molybdenum disulfide was prepared as nanotubes and fulerene-like structures that bring new insights in the investigation of this important material.

Influência do material do destilador na composição química das aguardentes de cana: parte II

The quantitative chemical analysis of the Brazilian sugar cane spirit distilled from glass column packaged with copper, stainless steel, aluminum sponge, or porcelain balls is described. The main chemical compounds determined by gas chromatography coupled with flame ionization (FID) and flame photometric (FPD) detectors and liquid chromatography coupled with diode array detector are aldehydes, ketones, carboxylic acids, alcohols, esters and dimethylsulfite (DMS). The spirits produced either in columns filled with copper or aluminum pot still exhibits the lowest DMS contents but the higher sulfate and methanol contents, whereas spirits produced in stainless steel or porcelain showed higher DMS concentration and lower teors of sulfate ion and methanol. These observations are coherent with DMS oxidation to sulfate, with methanol as by product, in the presence of either copper or aluminum.

Determination of the HMX and RDX content in synthesized energetic material by HPLC, FT-MIR, and FT-NIR spectroscopies

A new method has been developed for determining the content of mixtures of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), the HMX/RDX ratio, in explosive compositions by Fourier transform infrared spectroscopy (FT-IR), in the regions MIR (mid infrared) and NIR (near infrared) with reference values obtained by chromatographic analysis (HPLC). Plots of relative MIR (A917 / A783) or NIR absorbance values (A4412 / A4317) versus HMX/RDX ratio determined by HPLC analysis revealed good linear relationships.

Fish colonization of artificial reefs in a large Neotropical reservoir: material type and successional changes

Artificial reefs have barely been used in Neotropical reservoirs (about five studies in three reservoirs), despite their potential as a fishery management tool to create new habitats and also to understand fish ecology. We experimentally assessed how reef material (ceramic, concrete, and PVC) and time modulated fish colonization of artificial reefs deployed in Itaipu Reservoir, a large reservoir of the mainstem Parana´ River, Brazil. Fish richness, abundance, and biomass were significantly greater in the reef treatments than at control sites. Among the experimental reefs, ceramic followed by the concrete treatments were the materials most effectively colonized, harboring the majority of the 13 fish species recorded. Although dependent on material type, many of the regularities of ecological successions were also observed in the artificial reefs, including decelerating increases in species richness, abundance, mean individual size, and species loss rates with time and decelerating decreases of species gain and turnover rates. Species composition also varied with material type and time, together with suites of life history traits: more equilibrium species (i.e., fishes of intermediate size that often exhibit parental care and produce fewer but larger offspring) of the Winemiller-Rose model of fish life histories prevailed in later successional stages. Overall, our study suggests that experimental reefs are a promising tool to understand ecological succession of fish assemblages, particularly in tropical ecosystems given their high species richness and low seasonality

Validation and statistical analysis of two high performance liquid chromatography methods for the determination of indinavir sulfate raw material and capsules

Two high performance liquid chromatography (HPLC) methods for the quantitative determination of indinavir sulfate were tested, validated and statistically compared. Assays were carried out using as mobile phases mixtures of dibutylammonium phosphate buffer pH 6.5 and acetonitrile (55:45) at 1 mL/min or citrate buffer pH 5 and acetonitrile (60:40) at 1 mL/min, an octylsilane column (RP-8) and a UV spectrophotometric detector at 260 nm. Both methods showed good sensitivity, linearity, precision and accuracy. The statistical analysis using the t-student test for the determination of indinavir sulfate raw material and capsules indicated no statistically significant difference between the two methods.

Estudo de homogeneidade de lote de material silício metálico candidato a material de referência

From the perspective of the uncertainties in chemical measurements all uncertainty sources should be part of the uncertainty of the reference material. When the primary methods are not available, interlaboratorial comparisons are used as a means of certification. The material to be distributed to the laboratories should have its homogeneity confirmed. The uncertainty due to this factor will be added to the characterization uncertainty. This work presents a homogeneity study of a lot of silicon metal of chemical degree where the uncertainty due to inhomogeneity is obtained using analysis of variance.

Influência do material e volume do porta-amostra na determinação termogravimétrica do teor de cinzas em mel

The results suggest that the two variables studied are significant and that they may be independently optimized. The material of the sample holder interferes with the incineration process only due to the amount of heat transfered. The sample holder volume aids diffusion of the atmosphere to the honey sample, minimizing the foaming effect. According to the results, for the thermogravimetric analysis of ash content in honey, sample holders of platinum or alumina of 150 µL are indicated.

Análise de fármacos em material biológico: acoplamento microextração em fase sólida "no tubo" e cromatografia líquida de alta eficiência

A new solid phase microextraction (SPME) system, known as in-tube SPME, was recently developed using an open tubular fused-silica capilary column, instead of an SPME fiber, as the SPME device. On-line in-tube SPME is usually used in combination with high performance liquid chromatography. Drugs in biological samples are directly extracted and concentrated in the stationary phase of capillary columns by repeated draw/eject cycles of sample solution, and then directly transferred to the liquid chromatographic column. In-tube SPME is suitable for automation. Automated sample handling procedures not only shorten the total analysis time, but also usually provide better accuracy and precision relative to manual techniques. In-tube SPME has been demonstrated to be a very effective and highly sensitive technique to determine drugs in biological samples for various purposes such as therapeutic drug monitoring, clinical toxicology, bioavailability and pharmacokinetics.

Determinação de manganês em material particulado atmosférico de ambientes de trabalho utilizando eletrodo de diamante dopado com boro e voltametria de onda quadrada com redissolução catódica

A boron-doped diamond electrode is used for determination of Mn(II) in atmospheric particulate matter by square wave cathodic stripping voltammetry. The analytical curve was linear for Mn(II) concentrations between 5.0 and 37.5 µg L-1, with quantification limit of 3.6 µg L-1. The precision was evaluated by the relative standard deviation, with values between 5.1% and 9.3%. The electrode is free of adsorption, minimizing memory effects. Samples collected in the workplace atmosphere of a foundry had Mn(II) concentrations between 0.4 and 4 µg m-3. No significant differences were observed between the proposed method and inductively coupled plasma optical emission spectroscopy.

Non-resorbable glass fibre-reinforced composite with porous surface as bone substitute material: Experimental studies in vitro and in vivo focused on bone-implant interface

The development of load-bearing osseous implant with desired mechanical and surface properties in order to promote incorporation with bone and to eliminate risk of bone resorption and implant failure is a very challenging task. Bone formation and resoption processes depend on the mechanical environment. Certain stress/strain conditions are required to promote new bone growth and to prevent bone mass loss. Conventional metallic implants with high stiffness carry most of the load and the surrounding bone becomes virtually unloaded and inactive. Fibre-reinforced composites offer an interesting alternative to metallic implants, because their mechanical properties can be tailored to be equal to those of bone, by the careful selection of matrix polymer, type of fibres, fibre volume fraction, orientation and length. Successful load transfer at bone-implant interface requires proper fixation between the bone and implant. One promising method to promote fixation is to prepare implants with porous surface. Bone ingrowth into porous surface structure stabilises the system and improves clinical success of the implant. The experimental part of this work was focused on polymethyl methacrylate (PMMA) -based composites with dense load-bearing core and porous surface. Three-dimensionally randomly orientated chopped glass fibres were used to reinforce the composite. A method to fabricate those composites was developed by a solvent treatment technique and some characterisations concerning the functionality of the surface structure were made in vitro and in vivo. Scanning electron microscope observations revealed that the pore size and interconnective porous architecture of the surface layer of the fibre-reinforced composite (FRC) could be optimal for bone ingrowth. Microhardness measurements showed that the solvent treatment did not have an effect on the mechanical properties of the load-bearing core. A push-out test, using dental stone as a bone model material, revealed that short glass fibre-reinforced porous surface layer is strong enough to carry load. Unreacted monomers can cause the chemical necrosis of the tissue, but the levels of leachable resisidual monomers were considerably lower than those found in chemically cured fibre-reinforced dentures and in modified acrylic bone cements. Animal experiments proved that surface porous FRC implant can enhance fixation between bone and FRC. New bone ingrowth into the pores was detected and strong interlocking between bone and the implant was achieved.

Composição elementar do material particulado presente no aerossol atmosférico do município de Sete Lagoas, Minas Gerais

The main objective of this study was the identification of sources generating particulate matter in the atmospheric aerosols of Sete Lagoas, Minas Gerais. The measurement of the mineral composition was accomplished by X-ray diffractometry and the elemental concentration by neutron activation analysis. The results showed that Al, Cl, Cu, Fe, K, Mg and Na are the predominant chemical elements in the total suspended particles (TPS). The presence of Na, Ba, Cl, Cu, Eu, Fe and Sm in those particles with aerodynamic diameter smaller than 10 µm (PM10), indicates that soil dust and ceramic and pig iron industries are the main sources of air quality degradation in the region.