Titanium dental implants coated with Bonelike®: Clinical case report

The aim of the study was to evaluate the direct bone bonding and osteointegration of the commercial pure (cp Ti) implants coated with Bonelike® synthetic bone graft by plasma spraying. The Bonelike® coated implant was placed in the mandible of a 40-year-old patient and it was removed after a healing period of 3 months with a trephine of 6 mm diameter. The structure of the coating and new bone/implant interface of retrieved samples were evaluated using scanning electron microscopy (SEM) and histological analysis using light microscopy. In vivo microstructure observations of Bonelike® coated retrieved implants showed excellent bone remnants on its surface without any tissue and inflammatory signs observed. The reported Bonelike® coated (cp Ti) implants improved primary stability, which may increase the lifetime of the implant. Bonelike® coated dental implants proved to be highly bioactive with extensive new bone formation and strongly bonded to Bonelike® coating.     

Effect of dendritic arm spacing on mechanical properties and corrosion resistance of Al 9 Wt Pct Si and Zn 27 Wt Pct Al alloys

It has been reported that the mechanical properties and the corrosion resistance (CR) of metallic alloys depend strongly on the solidification microstructural arrangement. The correlation of corrosion behavior and mechanical properties with microstructure parameters can be very useful for planning solidification conditions in order to achieve a desired level of final properties. The aim of the present work is to investigate the influence of heat-transfer solidification variables on the microstructural array of both Al 9 wt pct Si and Zn 27 wt pct Al alloy castings and to develop correlations between the as-cast dendritic microstructure, CR, and tensile mechanical properties. Experimental results include transient metal/mold heat-transfer coefficient (h _i), secondary dendrite arm spacing (λ₂), corrosion potential (E _Corr), corrosion rate (i _Corr), polarization resistance (R ₁), capacitances values (Z _CPE), ultimate tensile strength (UTS, σ _u ), yield strength (YS, σ _y ), and elongation. It is shown that σ _U decreases with increasing λ₂ while the CR increases with increasing λ₂, for both alloys experimentally examined. A combined plot of CR and σ _U as a function of λ₂ is proposed as a way to determine an optimum range of secondary dendrite arm spacing that provides good balance between both properties.     

Corrosion resistance evaluation of the UNS S31803 duplex stainless steels aged at low temperatures (350 to 550°C) using DLEPR tests

This work describes the investigation of the corrosion evaluation of UNS S31803 duplex stainless steels aged at low temperatures using double loop electrochemical potentiokinetic reactivation tests (DLEPR). A wrought duplex stainless steel (DSS) UNS S31803 was aged at four temperatures in the 350—550°C range for times up to 1000 h. The hardening and embrittlement effects due to aging were also determined. An important decrease in corrosion resistance was observed in the samples aged at 475 and 550°C, but the samples aged at 350 and 400°C were not affected. Healing was observed in the samples aged for long times (1000 h at 475°C and 500 h at 550°C).     

Multimode Equivalent Networks for the Design and Analysis of Frequency Selective Surfaces

A modular technique originally proposed for waveguide junctions, the multimode equivalent network approach based on the integral equation formulation (IEMEN), is extended to the analysis of multilayer frequency selective surfaces integrated with waveguide array antennas. This technique represents each layer and transition between layers in terms of a generalized impedance or admittance matrix, obtained directly from the solution of an integral equation with reduced kernel. Thanks to the adopted formulation, the integral equation needs to be solved only in a limited set of frequency points. The IEMEN method is validated by comparison with results available in literature.     

Localization of sensitive areas of power AC switch under thermal laser stimulation

Thermal laser stimulation (TLS) is a widely used tool in a failure analysis laboratory to detect defects in integrated circuits. TLS can also be used for good device characterization. In this paper, we apply TLS – and especially optical beam induced resistance change (OBIRCH) method – to localization of electrically high stressed areas. We test this process with a new product from power AC switch family without failure. We localize several sensitive areas involved during and after switching, which are similar to the ones obtained by electrical simulations.     

Copolymerization of methyl- and buthylmethacrylate with electron-donor N-(2-hydroxyethyl)carbazolyl methacrylate and electron-acceptor (β-hydroxyethyl)-3,5-dinitrobenzoyl methacrylate

Summary The radical copolymerization of methyl- and butyl methacrylates with an electrondonor monomer: N-(2-hydroxyethyl)-carbazolyl methacrylate and an electron-acceptor monomer: (β-hydroxyethyl)-3,5-dinitrobenzoyl-methacrylate respectively, in dioxane at 60°C was investigated. The reactivity ratios of the binary systems were computed by using the Kelen-Tüd?s method. The azeothropic compositions were established according to the respective copolymerization diagrams.     

Effectiveness of cement-based systems for stabilization and solidification of spent pot liner inorganic fraction

Approximately 7000 t of spent pot liner (SPL) wastes are generated annually from activities associated with Alumi;nio Brasileiro S.A. (ALBRAS) plant located at Barcarena, Pará state, Brazil. The inorganic fraction of SPL contains high level of toxic compounds like cyanide and fluoride; its safe disposal has been the subject of serious discussions in Brazil. This study evaluated the option of a cement-based stabilization/solidification system as an effective means for safe disposal of SPL inorganic fraction in the field. The studies were carried out with concrete hexagonal blocks manufactured with a constant mass of 10% (w/w) of waste, 20% (w/w) of cement, and varied percentages of water, coarse aggregate, sand, and additives. The concrete matrices porosity and compressive strength were controlled by using microsilica (MS) and superplaticizer (SP). The results showed an average pH values for the SPL inorganic fraction and fragmented blocks of 10.2 and 11.1, respectively. Mixing the waste with concrete ingredients the solidification/stabilization effectiveness for the leachable cyanides and fluorides were of 59.33 and 57.95%, respectively. The results showed that the water/cement (W/C) ratio reduction through superplasticizer addition improved the compressive strength and the required value of 35 MPa was reached with blocks manufactured with 10 and 15% (weight of cement) of microsilica, after 28 days of curing time.     

A zeolite with interconnected 8-, 10- and 12-ring pores and its unique catalytic selectivity

One of the major goals in catalysis is to improve the capabilities of microporous materials. This can be accomplished by synthesizing new zeolites with controlled pore architectures. In particular, zeolites containing channels of different sizes in the same structure are desirable. Here, we report a zeolite containing fully interconnected 8-, 10- and 12-membered-ring pores, synthesized by combining the structure-directing effect of the organic 1,5-bis-(methylpyrrolidinium)-pentane and the framework isomorphic substitution of germanium for silicon. Analysis of the crystal structure determined by direct methods from synchrotron powder diffraction data reveals 16 independent tetrahedrally coordinated atoms. This thermally and hydrothermally stable zeolite structure, when synthesized in its acidic form by incorporating aluminium in the framework, presents unique catalytic shape-selectivity effects derived from its particular pore topology.