Residues of different gel formulations on dentinal walls: A SEM/EDS analysis

The aim of this study was to evaluate the presence of residues of sodium hypochlorite gel, chlorhexidine gel, and EDTA gel on dentinal walls after canal preparation through chemical SEM‐ elemental chemical microanalysis (EDS) analysis. Forty‐eight single‐rooted teeth were selected. They had their crowns sectioned and were instrumented with a reciprocating system. The canals were irrigated with 5 mL of saline solution during root canal preparation. After instrumentation, the root canals were irrigated with 3 mL 17% EDTA followed by 1 min of ultrasonic passive activation (3× 20 sec) to remove the smear layer, and then irrigated with 3 mL of saline solution. The specimens were randomized into three groups (n = 12) according to the chemical substance that filled the root canal for 30 min: GI: 5.5% sodium hypochlorite gel; GII: 2% chlorhexidine gel; GIII: 24% EDTA gel; Negative control group: no substance was used. Then, the root canals were irrigated with 6 mL of saline solution followed by 1 min of ultrasonic passive activation (3× 20 sec). After ultrasonic activation, the canals were irrigated with 2 mL saline. The roots were sectioned, and the percentage of each chemical element present in the samples was analyzed through chemical SEM‐EDS microanalysis. All experimental groups showed a significantly higher percentage of chemical elements (Na and/or Cl) than the control group (P < 0.03). This in vitro study has shown that, regardless of chemical solutions used even after the final irrigation protocol, chemical residues of different substances remained attached to the root canal walls. Microsc. Res. Tech. 78:495–499, 2015. © 2015 Wiley Periodicals, Inc.     

Chain extension reaction in solid‐state polymerization of recycled PET: The influence of 2,2′‐bis‐2‐oxazoline and pyromellitic anhydride

Conventional and chain extended‐modified solid‐state polymerization (SSP) of postconsumer poly(ethylene terephthalate) (PET) from beverage bottles was investigated. SSP was carried out at several temperatures, reaction times, and 2,2′‐bis‐2‐oxazoline (OXZ) or pyromellitic anhydride (ANP) concentrations. The OXZ was added by impregnation with chloroform or acetone solution. Higher molecular weights were reached when the reaction was carried out with OXZ, resulting in bimodal distribution. The molecular weights of the flakes reacted at 230°C for 4 h were 85,000, 95,000, and 100,000 for samples impregnated with 0, 0.5, and 1.25 wt % OXZ solution, respectively. In the case of reactions with ANP, branched chains were obtained. The thermal and thermal‐mechanical‐dynamic properties of these high‐molecular‐weight recycled PET were determined. For OXZ‐reacted samples, the reduction of crystallinity was observed as the reaction time was increased, becoming evident the destruction of the crystalline phase. The chain extended samples did not show changes in thermal relaxations or thermal degradation behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ecological and biological determinants of trace elements accumulation in liver and kidney of Pontoporia blainvillei

The present work tested whether ecological and biological variables have an influence on the assimilation of trace elements by the tissues of a cetacean from the Western South Atlantic Ocean. No significant differences were observed in the concentrations for both sexes. As individuals from the two sampling areas belong to distinct genetic and morphological populations, animals of similar body length were older on the southeastern than on the southern coast. The liver showed the highest concentrations of mercury, whereas the highest levels of cadmium were found in the kidney. Hepatic mercury, cadmium and selenium in individuals from the south coast were about four times as high as those from the southeast coast. However, arsenic in the liver and kidney were similar in both coastal areas. Hepatic mercury, cadmium and selenium concentrations increased with body length in individuals from the southeastern coast, although no significant correlations (P>0.05) were observed between body length from either area and the renal and hepatic As concentrations. A significant positive linear relationship was observed between molar concentrations of Hg and Se in the liver of all individuals from both areas (r2=0.93; P<0.001), presenting Se:Hg ratios close to 4. Differences found among the concentrations of Hg, Cd and Se in dolphins from both areas were probably due to the preferred prey, bioavailability of elements in each marine environment, and environment variables (water temperature, net primary production). As a consequence, concentrations of trace elements in the tissues of this species can be considered to be a result of the surrounding environment.     

Determination of sodium,potassium, calcium,magnesium, zinc and iron in emulsified chocolate samples by flame atomic absorption spectrometry

In this study, oil-in-water formulations were optimized to determine sodium, potassium, calcium, magnesium, zinc, and iron in emulsified chocolate samples by flame atomic absorption spectrometry (FAAS). This method is simpler and requires fewer reagents when compared with other sample pre-treatment procedures and allows the calibration to be carried out using aqueous standards. Octyl stearate was used as oily phase. Tween 80 and Triton X100 were tested as surfactants. The optimum type and proportion of formulations were determined and their choice depended on the element studied. The emulsion preparation was performed by a conventional method that involves mixing both phases at 75 ± 5 °C by magnetic stirring and phase inversion to change the water-to-oil ratio by increasing the volume of the surfactant-water external phase and correspondingly decreasing the volume of internal phase. The validation of the method was performed against a baking chocolate standard reference material (SRM 2384) and recoveries ranged from 88.6% for K to 105.5% for Zn. The proposed method allowed the evaluation of the essential metal status of chocolate with minimum sample manipulation and was reproducible and economical.     

MASS TRANSFER AND DIFFUSION COEFFICIENT DETERMINATION IN THE WET AND DRY SALTING OF MEAT

ABSTRACT

Dehydrated salted meat is widely used in Brazil as a very important source of animal protein. The main objective of this kind of processing is water removal. initially by osmotic pressure changes and then by drying, resulting in a product with intermediate moisture levels.

In this work, mass transfer and salt diffusion in pieces of meat submitted to wet and dry salting were studied. Slabs of beef m. trapezius with an infinite plate geometry were salted in a NaCl saturated solution or in a dry salt bed, at two temperatures (10 and 20°C) and different time exposures (120 min and 96 hours). Equilibration studies were extended up to six days.

It was observed that water loss increased with salt uptake, for increasing periods of times. At 20°C the moisture loss was higher than it was at 10°C in both salting processes. On the other hand, the kinetics of salt uptake and moisture loss were of greater importance in the process of dry salting than in that of wet salting.

The salt diffusion coefficient for wet salting was 0.26 × 10^?10m²/s at20°C and 0.25 × 10^?10 m²/s at 10°C and for the dry salting the values were 19.37 × 10^?10 m²/s at 20°C and 17.21 × 10^?10 m²/s at 10°C.     

Presynchronization with Double-Ovsynch improves fertility at first postpartum artificial insemination in lactating dairy cows

The objective of this study was to compare circulating progesterone (P4) profiles and pregnancies per AI (P/AI) in lactating dairy cows bred by timed artificial insemination (TAI) following Ovsynch-56 after 2 different presynchronization protocols: Double-Ovsynch (DO) or Presynch-Ovsynch (PS). Our main hypothesis was that DO would increase fertility in primiparous cows, but not in multiparous cows. Within each herd (n = 3), lactating dairy cows (n = 1,687; 778 primiparous, 909 multiparous) were randomly assigned to DO [n = 837; GnRH-7d-PGF_2α-3d-GnRH-7d-Ovsynch-56 (GnRH-7d-PGF_2α-56h-GnRH-16hTAI)] or PS (n = 850; PGF_2α-14d-PGF_2α-12d-Ovsynch-56). In 1 herd, concentrations of P4 were determined at the first GnRH (GnRH1) of Ovsynch-56 and at d 11 after TAI (n = 739). In all herds, pregnancy was diagnosed by palpation per rectum at 39 d. In 1 herd, the incidence of late embryo loss was determined at 74 d, and data were available on P/AI at the subsequent second service. Presynchronization with DO reduced the percentage of animals with low P4 concentrations (<0.50 ng/mL) at GnRH1 of Ovsynch-56 (5.4 vs. 25.3%, DO vs. PS). A lesser percentage of both primiparous and multiparous cows treated with DO had low P4 concentrations at GnRH1 of Ovsynch-56 (3.3 vs. 19.7%, DO vs. PS primiparous; and 8.8 vs. 31.9%, DO vs. PS multiparous). Presynchronization with DO improved P/AI at the first postpartum service (46.3 vs. 38.2%, DO vs. PS). Statistically, a fertility improvement could be detected for primiparous cows treated with DO (52.5 vs. 42.3%, DO vs. PS, primiparous), but only a tendency could be detected in multiparous cows (40.3 vs. 34.3%, DO vs. PS, multiparous), consistent with our original hypothesis. Presynchronization treatment had no effect on the incidence of late embryo loss after first service (8.5 vs. 5.5%, DO vs. PS). A lower body condition score increased the percentage of cows with low P4 at GnRH1 of Ovsynch-56 and reduced fertility to the TAI. In addition, P4 concentration at d 11 after TAI was reduced by DO. The method of presynchronization at first service had no effect on P/AI at the subsequent second service (34.7 vs. 36.5%, DO vs. PS). Thus, presynchronization with DO induced cyclicity in most anovular cows and improved fertility compared with PS, suggesting that DO could be a useful reproductive management protocol for synchronizing first service in commercial dairy herds.     

Effect of different surface processing protocols in three-dimensional images for rapid prototyping

The aim of the study was to evaluate the accuracy of virtual three-dimensional reconstructions of human dry mandibles, produced with different surface processing protocols. Three-dimensional images were built from computed tomography scans of 10 dry mandibles, and the surface was smoothed, refined, or both, generating 30 different images. Linear measurements from anatomical landmarks were calculated and compared with the corresponding measurements of the original dry mandible (gold standard). The results showed no differences between the models that were just refined or just smoothed (p > 0.05), when compared to the gold standard. When these two tools were applied together, there was a statistically significant difference (p < 0.01). In conclusion, the application of a single processing tool (smoothing or refinement) in the virtual models does not affect the anatomical measures. However, the simultaneous application of both tools increases the differences between the reconstructions and the original anatomical parts.     

Effect of Amphipathic HIV Fusion Inhibitor Peptides on POPC and POPC/Cholesterol Membrane Properties: A Molecular Simulation Study

T-20 and T-1249 fusion inhibitor peptides were shown to interact with 1-palmitoyl-2-oleyl-phosphatidylcholine (POPC) (liquid disordered, ld) and POPC/cholesterol (1:1) (POPC/Chol) (liquid ordered, lo) bilayers, and they do so to different extents. Although they both possess a tryptophan-rich domain (TRD), T-20 lacks a pocket binding domain (PBD), which is present in T-1249. It has been postulated that the PBD domain enhances FI interaction with HIV gp41 protein and with model membranes. Interaction of these fusion inhibitor peptides with both the cell membrane and the viral envelope membrane is important for function, i.e., inhibition of the fusion process. We address this problem with a molecular dynamics approach focusing on lipid properties, trying to ascertain the consequences and the differences in the interaction of T-20 and T-1249 with ld and lo model membranes. T-20 and T-1249 interactions with model membranes are shown to have measurable and different effects on bilayer structural and dynamical parameters. T-1249’s adsorption to the membrane surface has generally a stronger influence in the measured parameters. The presence of both binding domains in T-1249 appears to be paramount to its stronger interaction, and is shown to have a definite importance in membrane properties upon peptide adsorption.     

Natural silica fiber as reinforcing filler of nylon 6

Short silica fiber (SF) content on the mechanical and morphological properties of composites based on nylon 6 and rubber-toughened nylon 6 matrices was examined. Binary nylon 6/SF and ternary [nylon 6/EPDM-g-MA (ethylene–propylene–diene grafted with maleic anhydride)/SF] composites containing 0–20 wt% SF were formulated. The flexural modulus increased with the SF content at all fiber compositions investigated; however, the value of this property gradually diminished when 20 wt% rubber was added to the polymer. Notched Izod impact strength of 80/20 nylon 6/EPDM-g-MA blend was reduced up to 50% with the addition of 5 wt% SF. However, these composites still retained good stiffness and toughness and presented a good interfacial adhesion between the phases. The results suggest that silica fibers can be employed as an alternative reinforcement of nylon 6 matrices, resulting in materials with useful properties.     

Novel supports for nickel-based catalysts for the partial oxidation of methane

Zirconia-supported nickel catalysts with different amounts of aluminum (Al/Zr = 0.2, 1 and 2) were studied in this work in order to find alternative supports for nickel-based catalysts for the partial oxidation of methane. This reaction is a promising route for producing hydrogen and syngas for different applications. Samples were prepared by precipitation and impregnation techniques, characterized by several techniques and evaluated in the partial oxidation of methane in the range of 450–750 °C and 1 atm. It was found that aluminum affects the textural and catalytic properties of zirconia-supported nickel catalysts. The tetragonal phase of zirconia was stabilized by aluminum and gamma-alumina was also found in the aluminum-richest samples. Aluminum increased the porosity and the specific surface area of the solids. The catalytic activity also increased with the amount of aluminum in solids probably due to the stronger interaction of nickel with the support, which slowly generates active sites during the reduction step. The methane conversion and hydrogen selectivity increased with temperature, indicating no deactivation. The hydrogen to carbon monoxide molar ratio decreased due to aluminum but was not significantly affected by temperature. The coke produced was not harmful to the catalysts and aluminum affected its amount, although no simple relationship was found between these parameters. The most promising catalyst was the sample with aluminum to zirconium molar ratio of 2, which showed high activity and hydrogen selectivity and was stable under the reaction condition.