Annealing behavior of ferritic-martensitic 9%Cr-ODS-Eurofer steel

Oxide dispersion strengthened ferritic-martensitic steels are potential candidates for applications in future fusion power plants. High creep resistance, good oxidation resistance, reduced neutron activation and microstructural long-term stability at temperatures of about 650-700 degrees C are required in this context. In order to evaluate its thermal stability in the ferritic phase field, samples of the reduced activation ferritic-martensitic 9%Cr-ODS-Eurofer steel were cold rolled to 50% and 80% reductions and further annealed in vacuum from 300 to 800 degrees C for 1 h. The characterization in the annealed state was performed by scanning electron microscopy in the backscattered electron mode, high-resolution electron backscatter diffraction and transmission electron microscopy. Results show that the fine dispersion of Y-based particles (about 10 nm in size) is effective to prevent recrystallization. The low recrystallized volume fraction (<0.1) is associated to the nuclei found at prior grain boundaries and around large M(23)C(6) particles. Static recovery was found to be the predominant softening mechanism of this steel in the investigated temperature range. (c) 2010 Elsevier B.V. All rights reserved.

Three-dimensional analysis of fracture, corrosion and wear surfaces

A brief look at the history of fractography has shown a recent trend in the quantification of topographic parameters through the use of three-dimensional reconstruction techniques, which associate SEM stereoscopy and stereophotogrammetry software, allowing the calculation of the elevation measurement at numerous points of the topography due to the parallax that takes place during the tilting of the sample along the microscope eucentric plane. Several investigators have used reconstruction techniques to correlate some fractographic parameters, such as fractal dimension and fractured to projected area ratio, to the mechanical properties of materials, such as fracture toughness and tensile strength. So far, the search for a clear relationship between the fracture topography and mechanical properties has provided ambiguous results. The present work applied a surface metrology software to reconstruct three-dimensionally fracture surfaces (transgranular cleavage, intergranular and dimple fracture), corrosion pits and tribo-surfaces in order to explore the potential of this stereophotogrammetry technique. The existence of a variation in the calculated topographic parameters with the conditions of SEM image acquisition reinforces the importance of both good image acquisition and accurate calibration methods in order to validate this 3D reconstruction technique in metrological terms. Preliminary results did not indicate the existence of a clear relationship between either the true to project area ratio and CVN absorbed energy or the fractal dimension and CVN absorbed energy. It is likely that each fracture mechanism presents a proper relationship between the fractographic parameters and mechanical properties. (C) 2009 Elsevier Ltd. All rights reserved.

ANNEALING EFFECTS ON THE MICROSTRUCTURE OF FERRITIC-MARTENSITIC ODS-EUROFER STEEL

Oxide dispersion strengthened (ODS) ferritic/martensitic (FM) steels are promising candidates for structural applications in future fusion power reactors. In order to evaluate the thermal stability of 80% cold-rolled ODS-EUROFER, samples were annealed for 1 h at temperatures up to about 0.9 T(m), where T(m) is the absolute melting point. The characterization of the annealed samples was performed using transmission electron microscopy and electron backscatter diffraction. Results show that static recovery is the main softening mechanism of this steel when annealed below 800 degrees C. The volume fraction of recrystallized grains is quite small (below 0.10). Above 900 degrees C, martensitic transformation takes place causing pronounced hardening. Large M(23)C(6) particles are found at the grain boundaries after tempering at 750 degrees C for 2 h.

Effect of the processing conditions and the addition of trans-polyoctenylene rubber on the properties of natural rubber/styrene-butadiene rubber blends

In this study, the influence of the processing conditions and the addition of trans-polyoctenylene rubber (TOR) on Mooney viscosity, tensile properties, hardness, tearing resistance, and resilience of natural rubber/styrene-butadiene rubber blends was investigated. The results obtained are explained in light of dynamic mechanical and morphological analyses. Increasing processing time produced a finer blend morphology, which resulted in an improvement in the mechanical properties. The addition of TOR involved an increase in hardness, a decrease in tear resistance, and no effect on the resilience. It resulted in a large decrease in the Mooney viscosity and a slight decrease in the tensile properties if the components of the compounds were not properly mixed. The results indicate that TOR acted more as a plasticizer than a compatibilizer. (c) 2008 Wiley Periodicals, Inc.

Electrical and Mechanical Properties of Post-annealed SiC(x)N(y) Films

Amorphous SiC(x)N(y) films have been deposited on (100) Si substrates by RF magnetron sputtering of a SiC target in a variable nitrogen-argon atmosphere. The as-deposited films were submitted to thermal anneling in a furnace under argon atmosphere at 1000 degrees C for 1 hour. Composition and structure of unannealed and annealed samples were investigated by RBS and FTIR. To study the electrical characteristics of SiC(x)N(y) films, Metal-insulator-semiconductor (MIS) structures were fabricated. Elastic modulus and hardness of the films were determined by nanoindentation. The results of these studies showed that nitrogen content and thermal annealing affect the electrical, mechanical and structural properties of SiC(x)N(y) films.

Effects of mechanical properties, residual stress and indenter tip geometry on instrumented indentation data in thin films

In this work, an axisymmetric two-dimensional finite element model was developed to simulate instrumented indentation testing of thin ceramic films deposited onto hard steel substrates. The level of film residual stress (sigma(r)), the film elastic modulus (E) and the film work hardening exponent (n) were varied to analyze their effects on indentation data. These numerical results were used to analyze experimental data that were obtained with titanium nitride coated specimens, in which the substrate bias applied during deposition was modified to obtain films with different levels of sigma(r). Good qualitative correlation was obtained when numerical and experimental results were compared, as long as all film properties are considered in the analyses, and not only sigma(r). The numerical analyses were also used to further understand the effect of sigma(r) on the mechanical properties calculated based on instrumented indentation data. In this case, the hardness values obtained based on real or calculated contact areas are similar only when sink-in occurs, i.e. with high n or high ratio VIE, where Y is the yield strength of the film. In an additional analysis, four ratios (R/h(max)) between indenter tip radius and maximum penetration depth were simulated to analyze the combined effects of R and sigma(r) on the indentation load-displacement curves. In this case, or did not significantly affect the load curve exponent, which was affected only by the indenter tip radius. On the other hand, the proportional curvature coefficient was significantly affected by sigma(r) and n. (C) 2010 Elsevier B.V. All rights reserved.

Thin titanium oxide films deposited by e-beam evaporation with additional rapid thermal oxidation and annealing for ISFET applications

Titanium oxide (TiO(2)) has been extensively applied in the medical area due to its proved biocompatibility with human cells [1]. This work presents the characterization of titanium oxide thin films as a potential dielectric to be applied in ion sensitive field-effect transistors. The films were obtained by rapid thermal oxidation and annealing (at 300, 600, 960 and 1200 degrees C) of thin titanium films of different thicknesses (5 nm, 10 nm and 20 nm) deposited by e-beam evaporation on silicon wafers. These films were analyzed as-deposited and after annealing in forming gas for 25 min by Ellipsometry, Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM), Rutherford Backscattering Spectroscopy (RBS) and Ti-K edge X-ray Absorption Near Edge Structure (XANES). Thin film thickness, roughness, surface grain sizes, refractive indexes and oxygen concentration depend on the oxidation and annealing temperature. Structural characterization showed mainly presence of the crystalline rutile phase, however, other oxides such Ti(2)O(3), an interfacial SiO(2) layer between the dielectric and the substrate and the anatase crystalline phase of TiO(2) films were also identified. Electrical characteristics were obtained by means of I-V and C-V measured curves of Al/Si/TiO(x)/Al capacitors. These curves showed that the films had high dielectric constants between 12 and 33, interface charge density of about 10(10)/cm(2) and leakage current density between 1 and 10(-4) A/cm(2). Field-effect transistors were fabricated in order to analyze I(D) x V(DS) and log I(D) x Bias curves. Early voltage value of -1629 V, R(OUT) value of 215 M Omega and slope of 100 mV/dec were determined for the 20 nm TiO(x) film thermally treated at 960 degrees C. (C) 2009 Elsevier B.V. All rights reserved.

Three-Dimensional Stress Distribution in the Human Periodontal Ligament in Masticatory, Parafunctional, and Trauma Loads: Finite Element Analysis

Background: The presence of the periodontal ligament (PDL) makes it possible to absorb and distribute loads produced during masticatory function and other tooth contacts into the alveolar process via the alveolar bone proper. However, several factors affect the integrity of periodontal structures causing the destruction of the connective matrix and cells, the loss of fibrous attachment, and the resorption of alveolar bone. Methods: The purpose of this study was to evaluate the stress distribution by finite element analysis in a PDL in three-dimensional models of the upper central incisor under three different load conditions: 100 N occlusal loading at 45 degrees (model 1: masticatory load); 500 N at the incisal edge at 45 degrees (model 2: parafunctional habit); and 800 N at the buccal surface at 90 degrees (model 3: trauma case). The models were built from computed tomography scans. Results: The stress distribution was quite different among the models. The most significant values (harmful) of tensile and compressive stresses were observed in models 2 and 3, with similarly distinct patterns of stress distributions along the PDL. Tensile stresses were observed along the internal and external aspects of the PDL, mostly at the cervical and middle thirds. Conclusions: The stress generation in these models may affect the integrity of periodontal structures. A better understanding of the biomechanical behavior of the PDL under physiologic and traumatic loading conditions might enhance the understanding of the biologic reaction of the PDL in health and disease. J Periodontol 2009;80:1859-1867.

Three Dimensional Finite Element Analyses of Oral Structures by Computerized Tomography

Our aim was to document the benefits of three dimensional finite element model generations from computed tomography data as well as the realistic creation of all oral structures in a patient. The stresses resulting from the applied load in our study did not exceed the structure limitations, suggesting a clinically acceptable physiological condition.

Thermal Behavior, Microstructure, Polymorphism, and Crystallization Properties of Zero Trans Fats from Soybean Oil and Fully Hydrogenated Soybean Oil

Blends of soybean oil (SO) and fully hydrogenated soybean oil (FHSBO), with 10, 20, 30, 40, and 50% (w/w) FHSBO content were interesterified under the following conditions: 20 min reaction time, 0.4% sodium methoxide catalyst, and 500 rpm stirring speed, at 100 A degrees C. The original and interesterified blends were examined for triacylglycerol composition, thermal behavior, microstructure, crystallization kinetics, and polymorphism. Interesterification produced substantial rearrangement of the triacylglycerol species in all the blends, reduction of trisaturated triacylglycerol content and increase in monounsaturated-disaturated and diunsaturated-monosaturated triacylglycerols. Evaluation of thermal behavior parameters showed linear relations with FHSBO content in the original blends. Blend melting and crystallization thermograms were significantly modified by the randomization. Interesterification caused significant reductions in maximum crystal diameter in all blends, in addition to modifying crystal morphology. Characterization of crystallization kinetics revealed that crystal formation induction period (tau (SFC)) and maximum solid fat content (SFC(max)) were altered according to FHSBO content in the original blends and as a result of the random rearrangement. Changes in Avrami constant (k) and exponent (n) indicated, respectively, that-as compared with the original blends-interesterification decreased crystallization velocities and modified crystallization processes, altering crystalline morphology and nucleation mechanism. X-ray diffraction analyses revealed that interesterification altered crystalline polymorphism. The interesterified blends showed a predominance of the beta` polymorph, which is of more interest for food applications.

Zero trans fats from soybean oil and fully hydrogenated soybean oil: Physico-chemical properties and food applications

Blends of soybean oil (50) and fully hydrogenated soybean oil (FHSBO), with 10%, 20%, 30%, 40% and 50% FHSBO (w/w) content were interesterified under the following conditions: 0.4% sodium methoxide, 500 rpm stirring, 100 degrees C, 20 min. The original and interesterified blends were examined for triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused considerable rearrangement of triacylglycerol species, reduction of trisaturated triacylglycerol content and increase in monounsaturated and diunsaturated triacylglycerols, resulting in lowering of respective melting points. The interesterified blends displayed reduced SFC at all temperatures and more linear melting profiles as compared with the original blends. Yield values showed increased plasticity in the blends after the reaction. Isosolid diagrams before and after the reaction showed no eutectic interactions. The 90:10, 80:20, 70:30 and 60:40 interesterified SO:FHSBO blends displayed characteristics suited to application, respectively, as liquid shortening, table margarine, baking/confectionery fat and all-purpose shortenings/biscuit-filing base. (C) 2009 Elsevier Ltd. All rights reserved.

Nitric oxide donor trans-[RuCl([15]aneN(4))NO]2+as a possible therapeutic approach for Chagas` disease

Background and purpose: Benznidazole (Bz) is the therapy currently available for clinical treatment of Chagas` disease. However, many strains of Trypanosoma cruzi parasites are naturally resistant. Nitric oxide (NO) produced by activated macrophages is crucial to the intracellular killing of parasites. Here, we investigate the in vitro and in vivo activities against T. cruzi, of the NO donor, trans-[RuCl([15]aneN(4))NO]2+. Experimental approach: Trans-[RuCl([15]aneN(4))NO]2+ was incubated with a partially drug-resistant T. cruzi Y strain and the anti-proliferative (epimastigote form) and trypanocidal activities (trypomastigote and amastigote) evaluated. Mice were treated during the acute phase of Chagas` disease. The anti-T. cruzi activity was evaluated by parasitaemia, survival rate, cardiac parasitism, myocarditis and the curative rate. Key results: Trans-[RuCl([15]aneN(4))NO]2+ was 10- and 100-fold more active than Bz against amastigotes and trypomastigotes respectively. Further, trans-[RuCl([15]aneN(4))NO]2+ (0.1 mM) induced 100% of trypanocidal activity (trypomastigotes forms) in vitro. Trans-[RuCl([15]aneN(4))NO]2+ induced permanent suppression of parasitaemia and 100% survival in a murine model of acute Chagas` disease. When the drugs were given alone, parasitological cures were confirmed in only 30 and 40% of the animals treated with the NO donor (3.33 mu mol center dot kg-1 center dot day-1) and Bz (385 mu mol center dot kg-1 center dot day-1), respectively, but when given together, 80% of the animals were parasitologically cured. The cured animals showed an absence of myocarditis and a normalisation of cytokine production in the sera. In addition, no in vitro toxicity was observed at the tested doses. Conclusions and implications: These findings indicate that trans-[RuCl([15]aneN(4))NO]2+ is a promising lead compound for the treatment of human Chagas` disease. This article is commented on by Machado et al., pp. 258-259 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2010.00662.x and to view a related paper in this issue by Silva et al. visit http://dx.doi.org/10.1111/j.1476-5381.2010.00524.x.

Enantioselective analysis of praziquantel and trans-4-hydroxypraziquantel in human plasma by chiral LC-MS/MS: Application to pharmacokinetics

A simple enantioselective method for the determination of praziquantel (PZQ) and trans-4-hydroxypraziquantel (4-OHPZQ) in human plasma was developed and validated by high-performance liquid chromatography/mass spectrometry. The plasma samples were prepared by liquid-liquid extraction using a mixture of methyl-tert-butylether/dichloromethane (2:1, v/v) as extraction solvent. The direct resolution of PZQ and 4-OHPZQ enantiomers was performed on a Chiralpak AD column using hexane-isopropanol (75:25, v/v) as the mobile phase. Diazepam was used as internal standard. The method described here is simple and reproducible. The quantitation limit of 1.25 ng/ml for each PZQ enantiomer and of 12.5 ng/ml for each 4-OHPZQ enantiomer permits the use of the method in studies investigating the kinetic disposition of a single dose of 1.5g racemic PZQ. Enantioselectivity in the kinetic disposition of PZQ and 4-OHPZQ was observed in the clinical study. with the demonstration of a higher proportion of the (+)-(S)-PZQ and (-)-(R)-4-OHPZQ enantiomers in plasma. (C) 2009 Elsevier B.V. All rights reserved.

Preparation and characterization of chitosan-treated alginate microparticles incorporating all-trans retinoic acid

Chitosan treated alginate microparticles were prepared with the purpose of incorporating all-trans retinoic acid (ATRA) using an inexpensive, simple and fast method, enhancing dermal localization and sustaining the release of ATRA into the skin. Microparticles characterization, drug-polymer interaction, release profile and in vitro skin retention were investigated. Microparticles presented spherical shape and drug loading capacity of 47%. The drug content of these microparticles was affected by ATRA concentration and by the solvent used and it was more weakly affected by chitosan concentration. The release of ATRA was also affected by chitosan concentration. Microparticles prepared with 0.4% chitosan (w/w) resulted in drug release with a more sustained profile. The results of in vitro retention studies showed that chitosan treated alginate microparticles decreased the drug retention in the stratum corneum (SC), where occur the skin irritation, but maintained the ATRA concentration in the deeper skin layers, where occur the pathologies treated with ATRA. Then, the microparticles developed in this work can be a good candidate to improve the topical therapy with retinoid.

Trypanocidal structure-activity relationship for cis- and trans-methylpluviatolide

The trypanocidal activity of racemic mixtures of cis- and trans-methylpluviatolides was evaluated in vitro against trypomastigote forms of two strains of Trypanosoma cruzi, and in the enzymatic assay of T. cruzi gGAPDH. The cytotoxicity of the compounds was assessed by the MTT method using LLC-MK2 cells. The effect of the compounds on peroxide and NO production were also investigated. The mixture of the trans stereoisomers displayed trypanocidal activity (IC(50) similar to 89.3 mu M). Therefore, it was separated by chiral HPLC, furnishing the and (+) (-)-enantiomers. Only the (-)-enantiomer was active against the parasite (IC(50) similar to 18.7 mu M). Despite being inactive, the (+)-enantiomer acted as an antagonistic competitor. Trans-methylpluviatolide displayed low toxicity for LLC-MK(2) cells, with an IC(50) of 6.53 mM. Furthermore, methylpluviatolide neither inhibited gGAPDH activity nor hindered peroxide and NO production at the evaluated concentrations. (C) 2008 Elsevier Ltd. All rights reserved.