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Base Material (base + material)
Kinds of Base Material Selected AbstractsJoining Strategies for Open Porous Metallic Foams on Iron and Nickel Base Materials,ADVANCED ENGINEERING MATERIALS, Issue 8 2007S. Longerich Within the Collaborative Research Centre (SFB) 561 "Thermally highly loaded, porous and cooled multilayer systems for combined cycle power plants" open porous Ni-based structures are developed for the requirements of an effusion cooling. A two-dimensional cooling strategy for the walls of combustion chambers, that allows the outflow of the cooling medium over the complete wall area of the combustion chamber, could be realized by an open porous metallic foam structure. The challenge is to join the porous foam structure with the solid substrate material. Capacitor discharge welding and laser beam welding/-brazing methods seems to be promising methods due to a minimum input of energy and, connected with this, a small joining zone. [source] Corrosion of coating materials in oxidizing and hydrogen chloride containing atmospheresMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2002S.C. Cha The boiler tubes in waste incinerator plants and power plants are mainly corrosive strained. This paper presents the corrosion behaviour of various coating materials in two corrosive atmospheres at 500°C. In a first test, Ni-based materials applied by High Velocity Oxygen Fuel Flame (HVOF)-spraying and Atmospheric Plasma Spraying (APS) as well as Cr-based materials obtained by diffusion coating process are tested in oxidizing atmosphere with water saturation. The results of the corrosion test in this H2O-O2 -N2 -atmosphere show that NiCr applied by HVOF is less oxidized than that applied by APS-coating, whereas NiCrBSi coating by APS shows higher resistance than that applied by HVOF-spraying. The diffusion coating of Cr/Si is better than that of pure Cr. In a second test, metallic Mo and W-based materials applied by thermal spraying are tested to verify their corrosion resistance in HCl-H2O-O2 -N2 -atmosphere. It is shown that pure Mo applied by APS on 13 CrMo 44 and WCrNi sprayed on 15 Mo 3 by HVOF as well as on 13 CrMo 44 show relatively high corrosion resistance, whereas Mo sprayed by APS on 15 Mo 3 is not resistant. Both tungsten-cobalt-chromium mixtures show extremely high oxidation rates. Base materials in both tests were the standard boiler tube materials 15 Mo 3 and 13 CrMo 44. But even the low corrosion rates of the best materials in these tests are higher compared to those of materials already presented by Cha et al. in an earlier paper. Korrosion von Beschichtungswerkstoffen in oxidierenden und chlorwasser-stoffhaltigen Atmosphären Die Wärmetauscherrohre von Müllverbrennungsanlagen und Kraftwerken sind hauptsächlich korrosiv beansprucht. Die vorliegende Veröffentlichung stellt das Korrosionsverhalten von verschiedenen Beschichtungswerkstoffen in zwei korrosiven Atmosphären bei einer Temperatur von 500°C vor. Zuerst wurden die durch Hochgeschwindigkeitsflammspritzen (HVOF) und atmosphärisches Plasmaspritzen (APS) aufgetragenen Ni-Basiswerkstoffe und die diffusionsbeschichteten Cr-Basiswerkstoffe in oxidierender Atmosphäre mit Wassersättigung getestet. Die Ergebnisse der Korrosionsversuche in der H2O-O2 -N2 -Atmosphäre zeigen, dass NiCr (HVOF) resistenter ist als durch APS Beschichtung, wobei die Beschichtung mit NiCrBSi durch APS höhere Beständigkeit als die durch HVOF zeigt. Eine diffusionsbeschichtete Cr/Si-Schicht zeigt höhere Beständigkeit als eine reine Cr-Schicht. In einer zweiten Versuchsreihe wurden metallisches Mo und W-Basiswerkstoffe auf Korrosionsbeständigkeit in HCl-H2O-O2 -N2 -Atmosphäre untersucht. Dabei zeigt sich, dass die Proben mit Mo (APS) auf 13 CrMo 44, sowie WCrNi (HVOF) auf 15 Mo 3 und 13 CrMo 44 relativ hohe Korrosionsbeständigkeiten besitzen. Dagegen ist Mo (APS) auf 15 Mo 3 nicht beständig. Beide W-Co-Verbindungen zeigen extrem hohe Oxidationsraten. Als Basiswerkstoffe wurden die Standard Kesselrohr-Werkstoffe 15 Mo 3 und 13 CrMo 44 gewählt. Aber auch die niedrigsten Korrosionsraten der besten Werkstoffe in dieser Untersuchung sind höher als diejenigen der in einer früheren Arbeit von Cha et al. vorgestellten Werkstoffe. [source] Microwave Assisted Synthesis of Yb:Y2O3 Based Materials for Laser Source Application,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Anna Luisa Costa Yb:Y2O3 submicrometric particles were synthesized through co-precipitation of Yb and Y nitrate in water. Microwave heating and controlled release of ammonia through urea decomposition at reaction temperature leaded to the formation of disaggregated, monosized spherical particles of carbo-hydroxy-nitrate precursors. Pure crystalline Yb:Y2O3 powder that preserved the described morphology was obtained after calcination in air at 800,°C for 30,min. This powder mixed with commercial alumina powder was used to produce transparent Yb:YAG ceramics. Improved properties in terms of powder morphology and reactivity were presented in comparison with powders obtained by traditional heating. [source] Enhanced Properties of Tin(IV) Oxide Based Materials by Field-Activated SinteringJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003Oana Scarlat The densification of SnO2 (0.9 mol),Sb2O3 (0.1 mol) solid solution without any additives was studied by conventional and field-activated sintering technique (FAST). FAST sintering achieved a relative density value of 92.4% at 1163 K for 10 min versus 61.3% in conventional sintering at 1273 K for 3 h. An abnormal reduction of the IR transmittance and a semiconductor defect structure with only one donor level in the SnO2 energy gap were noticed in the FAST-sintered as compared with the conventionally sintered Sn0.82Sb0.18O2 solid solution. A high charge carrier concentration (i.e., electronic conduction) was shown in the FAST-sintered sample by conductivity measurements and the negative values of the Seebeck coefficient. [source] The Decomposition of some RDX and HMX Based Materials in the One Dimensional Time to Explosion Apparatus.PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2007Part 2. Abstract Various methods of assessment have been applied to the One Dimensional Time to Explosion (ODTX) apparatus and experiments with the aim of allowing an estimate of the comparative violence of the explosion event to be made. Non-mechanical methods used were a simple visual inspection, measuring the increase in the void volume of the anvils following an explosion and measuring the velocity of the sound produced by the explosion over 1 metre. Mechanical methods used included monitoring piezo-electric devices inserted in the frame of the machine and measuring the rotational velocity of a rotating bar placed on the top of the anvils after it had been displaced by the shock wave. This last method, which resembles original Hopkinson Bar experiments, seemed the easiest to apply and analyse, giving relative rankings of violence and the possibility of the calculation of a "detonation" pressure. [source] Influence of anisotropy on a limit load of weld strength overmatched middle cracked tension specimensFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2003S. ALEXANDROV ABSTRACT A plane-strain upper bound limit load solution for weld strength overmatched middle cracked tension specimens (M(T) specimens), is found. It is assumed that the weld material is isotropic, but the base material is orthotropic and its axes of orthotropy are straight and parallel to the axes of symmetry of the specimen. A quadratic orthotropic yield criterion is adopted. The solution is based on a simple discontinuous kinematically admissible velocity field and is an extension of the corresponding solution for the specimen made of isotropic materials. These two solutions are compared to demonstrate the influence of anisotropy on the magnitude of the limit load. [source] Cover Picture: TiO2 Nanoparticle,Photopolymer Composites for Volume Holographic Recording (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 10 2005Mater. Abstract TiO2 nanoparticle,photopolymer composites have been employed for volume holographic recording, as reported by Sánchez and co-workers on p.,1623. Photoinduced segregation of the high refractive index, grafted nanoparticles between polymer-rich areas leads to improved refractive-index modulation amplitudes with respect to the base material without nanoparticles. The cover schematically shows a holographic grating registered in this nanocomposite material. These nanocomposite materials should enable the production of holographic optical elements to efficiently control light with angle and wavelength selectivity. This could be used, for example, in liquid-crystal display technology. A new and efficient photopolymer for the recording of volume holograms is presented. The material comprises a mixture of UV-sensitive acrylates and grafted titanium dioxide nanoparticles with an average size of 4,nm. We report the formation of holographic gratings with refractive-index modulation amplitudes of up to 15.5,×,10,3,an improvement of more than a factor of four over the base material without nanoparticles,while maintaining a low level of scattering and a high transparency in the visible-wavelength range. The influence of the composition of the acrylate system on the final properties of the holographic material is also investigated and discussed. The presence of multifunctional monomers favors the compositional segregation of the different components, while the addition of monofunctional acrylate, highly compatible with the grafting of the nanoparticles, favors the dilution of these nanoparticles. [source] Biocompatibility of various formula root filling materials for primary teethJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007Tsui-Hsien Huang Abstract The aim of this study was to compare the effects of different materials used in primary root canal fillings on the cell viability of human osteosarcoma cell lines. The experimental group contained six different types of root canal filling materials, including zinc oxide (ZnO) + eugenol + formocresol (FC), Ca(OH)2 + FC, Ca(OH)2 + Iodoform, Ca(OH)2 + Iodoform + camphorated parachlorophenol (CPC), Ca(OH)2 + CPC, and Vitapex. Cell viability tests were performed using tetrazolium bromide colorimetric (MTT) assay on human osteosacorma cell lines (U2OS). The results were analyzed using one-way analysis of variance (ANOVA) and Student,Newman,Keul's test with p < 0.05 showed statistical differences. The ZnO + eugenol + FC group and Ca(OH)2 + FC group showed the lowest survival rates (p < 0.05). The Ca(OH)2 + Iodoform + CPC group and Ca(OH)2 + CPC group showed significantly lower survival rates at concentrations above 6 ,L/mL (p < 0.05). The Ca(OH)2 + Iodoform group and Vitapex group showed the highest survival rates (p < 0.05). We concluded that the use of calcium hydroxide with iodoform as a root filling base material is a better option than other medications. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] The effect of the addition of poly(methyl methacrylate) fibres on some properties of high strength heat-cured acrylic resin denture base materialJOURNAL OF ORAL REHABILITATION, Issue 3 2003D. Jagger summary, The self-reinforcement of acrylic resin with butadiene styrene surface treated poly(methyl methacrylate) fibres has been reported to have the potential to substantially improve the transverse bend strength of conventional heat-cured acrylic resin. The aim of this study was to investigate the effect of the addition of butadiene styrene surface treated poly(methyl methacrylate) fibres in cross-ply arrangement to high impact acrylic resin on the transverse and impact strength. Specimens were prepared as specified in the International Standard Organization and British Standards for the Testing of Denture Base Resins (ISO 1567, 1988; BS 2487, 1989) and the British Standard Specification for Orthodontic resins (BS 6747, 1987) for transverse bend and impact testing. The impact strength was measured using a Zwick pendulum impact tester and the transverse bend strength measured using a Lloyds Instruments testing machine. The results showed that the impact strength was not improved with the addition of fibres, high impact acrylic resin with fibres (LF) 11·1 kJ m,2 and high impact acrylic resin (L) (12·5 kJ m,2). The modulus of rupture was decreased with the addition of fibres (57·8 MPa) for (LF) compared with (60·4 MPa) for (L). The modulus of elasticity was also reduced with the addition of fibres (1834·9 MPa) (LF) and 2086·2 MPa (L) as was the peak load (LF) (50·8 N) and (L) (55·8 N). It was concluded that the addition of surface treated poly(methyl methacrylate) fibres in cross-ply arrangement to high strength acrylic resin did not produce an improvement in the impact or transverse strength and cannot be recommended as a method of reinforcement. [source] Bonding strength between a hard chairside reline resin and a denture base material as influenced by surface treatmentJOURNAL OF ORAL REHABILITATION, Issue 12 2001C. R. Leles Direct relining of dentures made with hard chairside reline resins is faster than laboratory-processed reline systems and the patient is not without the prosthesis for the time necessary to perform the laboratory procedures. However, a weak bond between the autopolymerizing acrylic reline resins and the denture base material has been observed. This study evaluated the effect of six different surface treatments on the bond strength between a hard chairside reline acrylic resin and a heat-cured acrylic resin. Specimens of the heat-cured acrylic resin were divided into seven groups. One of these groups remained intact. In the other groups, a 10-mm square section was removed from the centre of each specimen. The bonding surfaces were then treated with (i) methyl methacrylate monomer, (ii) isobutyl methacrylate monomer, (iii) chloroform, (iv) acetone, (v) experimental adhesive and (vi) no surface treatment , control group. Kooliner acrylic resin was packed into the square sections and polymerized. The bonding strength was evaluated by a three-point loading test. The results were submitted to one-way analysis of variance (ANOVA) followed by a Tukey multiple range test at a 5% level of significance. No significant difference was found between the surface treatment with Lucitone 550 monomer or chloroform, but both were stronger than the majority of the other groups. The bond strength provided by all the surface treatments was lower than that of the intact heat-cured resin. [source] Polymer film formulations for the preparation of enteric pharmaceutical capsulesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2010Alan M. Smith Abstract Objectives Standard pharmaceutical capsules are designed to dissolve in the acidic environment of the stomach releasing the encapsulated contents for absorption. When release is required further along the gastrointestinal tract capsules can be coated with acid insoluble polymers to enable passage through the stomach and dissolution in the intestine. This paper describes formulations that have the potential to be used to produce two-piece hard capsules for post-gastric delivery without the requirement of an exterior coat. Methods The formulation uses three polysaccharides: sodium alginate, hypromellose and gellan gum to provide acid insolubility and the ability to form capsules using standard industrial equipment. Key findings The rheological profile, on cooling, of the base material, water content and thickness of the films were shown to be comparable with those of commercial capsules. The capsules remained intact for 2 h in 100 mm HCl at pH 1.2, and within 5 min of being removed from the acid and submerged in phosphate-buffered saline at pH 6.8 were ruptured. Conclusions Selected formulations from this study have potential for use as delayed release capsules. [source] Effect of Aluminum Oxide Addition on the Flexural Strength and Thermal Diffusivity of Heat-Polymerized Acrylic ResinJOURNAL OF PROSTHODONTICS, Issue 6 2008Ayman E. Ellakwa BDS Abstract Purpose: This work was undertaken to investigate the effect of adding from 5% to 20% by weight aluminum oxide powder on the flexural strength and thermal diffusivity of heat-polymerized acrylic resin. Materials and Methods: Seventy-five specimens of heat-polymerized acrylic resin were fabricated. The specimens were divided into five groups (n = 15) coded A to E. Group A was the control group (i.e., unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with aluminum oxide (Al2O3) powder to achieve loadings of 5%, 10%, 15%, and 20% by weight. Specimens were stored in distilled water at 37°C for 1 week before flexural strength testing to failure (5 mm/min crosshead speed) in a universal testing machine. Results were analyzed by one-way analysis of variance and post hoc Tukey paired group comparison tests (p < 0.05). Weibull analysis was used to calculate the Weibull modulus, characteristic strength, and the required stress for 1% and 5% probabilities of failure. Cylindrical test specimens (5 specimens/group) containing an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). Results: The mean flexural strength values of the heat-polymerized acrylic resin were (in MPa) 99.45, 119.92, 121.19, 130.08, and 127.60 for groups A, B, C, D, and E, respectively. The flexural strength increased significantly after incorporation of 10% Al2O3. The mean thermal diffusivity values of the heat-polymerized acrylic resin (in m2/sec) were 6.8, 7.2, 8.0, 8.5, and 9.3 for groups A, B, C, D, and E, respectively. Thermal diffusivities of the composites were found to be significantly higher than the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler, which suggested that the proper distribution of alumina powders through the insulating polymer matrix might form a pathway for heat conduction. Conclusion: Al2O3 fillers have potential as added components in denture bases to provide increased flexural strength and thermal diffusivity. Increasing the flexural strength and heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction. [source] Hot Isostatic Pressing of Cubic Boron Nitride,Tungsten Carbide/Cobalt (cBN,WC/Co) Composites: Effect of cBN Particle Size and Some Processing Parameters on their Microstructure and PropertiesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2007V. Martínez Cubic boron nitride (cBN)-cemented carbide composites have gained attraction over the last few years because of their potential uses as wear parts. The densification behavior of cBN,hard metal composites by glass encapsulation hot isostatic pressing,has been investigated. Composites with different cBN grades (from 0/0.5 to 6/12 ,m particle sizes) and cBN content (up to 50 vol%) were selected for this study. Near-full densification was obtained at temperatures between 1100° and 1200°C, and pressures between 150 and 200 MPa, respectively, while no phase transformation of cBN into the low-hardness hexagonal form has been detected by X-ray diffraction. The addition of cBN to the hard metal base material led to an increase of hardness, a significant increase of fracture toughness (KIC measured by Vickers indentation), and a moderate decrease of mechanical strength (determined by three-point bending). [source] In vitro adhesion of Candida species to denture base materialsMYCOSES, Issue 2 2006X. Y. He Summary Adhesion of Candida species to prosthetic acrylic resins is an essential first step in the pathogenesis of denture stomatitis. Data on the relative adhesion of pathogenic non- albicans Candida species to different denture base materials are sparse. The purpose of the present study was to investigate in vitro adhesion of C. albicans, C. glabrata, C. krusei and C. dubliniensis to four different denture base materials. Specimens of both heat-cured resins (VertexTM Rapid Simplified and ProBaseTM Hot) and cold-cured resins (Paladur® A and Paladur® B) were prepared using a novel method and the adhesion of four strains each of the foregoing Candida species evaluated microscopically using a soft imaging system. There was a significant difference in yeast adherence between Vertex and the other resins. Only C. glabrata attached to Vertex, while all the remainder of the tested species adhered to all other resins tested except ProBase, which resisted C. krusei adhesion. There was a significant difference in candidal adhesion between cold-cured and heat-cured resins for three Candida species (C. albicans, P = 0.039; C. glabrata, P = 0.002 and C. krusei, P = 0.000). The type of denture base material and whether they are heat-cured or cold-cured play an important role in modifying candidal adhesion. [source] From electronic grade to solar grade silicon: chances and challenges in photovoltaicsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2005S. Pizzini Abstract Photovoltaics is a promising but challenging opportunity for the environmentally clean production of electric energy, as the cost of the produced energy is still too high to compete with conventional thermal and nuclear sources, in spite of the scientific and technological progress occurred in this field after the first oil crisis of 1973. Among the problems which should be solved to make photovoltaics fully competitive, a breakthrough concerning the cost reduction of the base material is compulsory. Aim of this paper is to discuss the scientific and technological problems encountered in the development of solar silicon for its use in high efficiency and low cost solar cells, and to give some firm experimental evidences about its potentialities. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Evaluation of Adhesion and Wear Resistance of DLC Films Deposited by Various MethodsPLASMA PROCESSES AND POLYMERS, Issue 6-7 2009Takahiro Horiuchi Abstract Diamond-like carbon (DLC) coatings are currently being used in a wide variety of industrial fields because of their outstanding properties, such as high hardness and low friction coefficient, among others. DLC coatings have various characteristics depending on the deposition method used. However, they have a problem regarding adhesion with the base material, which is a major factor hindering their expanded application in other fields. The adhesion of DLC coatings is generally evaluated using Rockwell indentation tests and scratch tests. These test methods induce damage in the specimen with the application of a single load. Accordingly, there is a problem of low correlation between such test results and evaluations of the adhesion of coatings on actual components that undergo repeated sliding cycles. With the aim of resolving that problem, this study evaluated the damage condition of three types of DLC coatings having different physical properties using newly devised cyclic sliding test methods involving the application of a continuously increasing load. The evaluation results obtained with these new methods differed from the results of Rockwell tests and scratch tests. These new test methods are more able to reproduce the damage done to DLC coatings in actual sliding cycles. This paper describes the test procedures and the evaluation results obtained. [source] The effect of polyoxypropylene-montmorillonite intercalates on polymethylmethacrylatePOLYMER COMPOSITES, Issue 1 2009Nehal Salahuddin Polymethylmethacrylate (PMMA)-layered silicate nanocomposites have been prepared by in situ polymerization of commercial type of methylmethacrylate monomer (MMA), for denture base material, into organoclay. Organoclay was prepared through an ion exchange process between sodium cations in montmorillonite and NH3+ groups in polyethertriamine hydrochloride and polyoxypropylene triamine hydrochloride with different molecular weight (5000, 440). X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the structure of the resulting composites. Both intercalated and exfoliated nanocomposites were obtained depending on the type and amount of organoclay. The thermal decomposition temperatures of the nanocomposites were found to be higher than that of pristine polymer. PMMA was strongly fixed to inorganic surfaces, due to cooperative formation of electrostatic bonding between NH3+ group and negatively charged surface of layered silicate and amide linkage between PMMA and polyethertriamine or polyoxypropylene triamine. The effect of the organoclay on the hardness, toughness, tensile stress, and elongation at break of the polymer was studied and was compared with pristine polymer. The hardness and Izod impact strength of PMMA-organoclay nanocomposites were enhanced with the inclusion of clay. Tensile properties appear to be enhanced at certain organoclay content. However, the water absorption is slightly higher than the pristine PMMA. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Effects of welding procedures on mechanical and morphological properties of hot gas butt welded PE, PP, and PVC sheetsPOLYMER ENGINEERING & SCIENCE, Issue 4 2008Onur Balkan Mechanical and morphological properties of hot gas butt welds on polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) sheets for four different procedures, which are single and double V-welds with and without a welding shoe, were investigated. Besides, weldabilities of base materials were evaluated by rheological measurements. These revealed that weldabilities of PE and PP sheets were better than that of PVC. Welding energy (Ew), which is transferred onto weld surfaces, was calculated to evaluate weld quality. The results of tensile, impact, and bending tests indicated that the weld strengths of PVC sheets were lower than those of PE and PP sheets. When the welding shoe was used, weld strength increased significantly for each material because of the presence of sufficient welding pressure and the effective heating on surfaces. The best results were attained for the double V-welds with the welding shoe. Morphology of welded regions was evaluated by polarized light, stereo, and scanning electron microscopy. Polarized light microscopy studies indicated that the heat-affected zone (HAZ) consisted of welding rod core, molten zone, and deformed spherulitic zone, and the welding interface was indistinguishable from the base material when the welding pressure was enough. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Molecular-selective adsorption property of chemically surface modified nanoporous alumina membrane by di(1-naphthyl)silanediol to anthracenesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2010Kenji Kakiage Abstract Nano-porous alumina membrane (NPAM) formed by the anodic oxidation of aluminum is an attractive composite as the base material for a functional filter, because of its honeycombed ordered structure with large surface area per weight and also high shape stability. In this work, we investigated the adsorption properties of the NPAM possessing ,-electron systems on the surface, which were produced through chemical surface modification by di(1-naphthyl)silanediol, to aromatic compounds using anthracenes as typical aromatic compounds. The chemically surface-modified NPAM exhibited strong affinity to anthracene molecules and the affinity was observed to be weakened remarkably with the introduction of methyl and phenyl substituents to anthracene, indicating a molecular-selective adsorption property of the NPAM. Copyright © 2009 John Wiley & Sons, Ltd. [source] Urban [IM]plants Tactics for Recombining Landscape and Collective Space in Bonheiden, BelgiumARCHITECTURAL DESIGN, Issue 1 2008Els Verbakel Abstract Bonheiden, in the province of Antwerp in Belgium, lies in a region known for its exceptional natural beauty. Though the surrounding rural setting has remained protected this has often been to the detriment of urban life, as the built environment has been subject to a process of banal suburbanisation. Els Verbakel and Elie Derman explain how they propose to turn this situation around by creating public spaces that use the town's ,original landscape as the base material'. Copyright © 2008 John Wiley & Sons, Ltd. [source] Degradation of repaired denture base materials in simulated oral fluidJOURNAL OF ORAL REHABILITATION, Issue 3 2000C.-T. Lin This in vitro study evaluates the degradation of repaired denture bases upon immersion in a simulated oral fluid. Denture base materials (Luciton 199®), after being repaired by Repair Material® and Triad®, using three different joint surface designs (butt, round and 45 ° bevel), were immersed onto 99·5 vol.% ethanol/water solution (with similar solubility parameter) for various amounts of time (0,72 h). The flexural loads of the six combination of groups were measured by the three-point bending tests using a universal testing machine. Acoustic emission (AE) during sample fracturing were processed using the MISTRA 2001 system. The fracture pattern and surface details of the interface were examined with a scanning electronic microscope (SEM). Data were analysed using three-way anova and Tukey LSD tests. SEM micrographs of the fracture interface were used to differentiate the fracture mode. The flexural loads (2·72±0·51 Kgf) of the round joint specimens were significantly higher (P<0·05) than those (butt: 1·66±0·38 Kgf, 45 ° bevel: 1·93±0·41 Kgf) of the other two designs. This corresponds to the microscopic examination in which more cohesive failure mode was found for the round joint group after storage. The flexural loads (2·54±0·39 Kgf) of the specimens repaired with Triad® were significantly higher (P<0·05) than those (1·59±0·40 Kgf) of specimens repaired with Repair Material®. Significant progressive reduction of the flexural load and/or AE signals of the specimens was noted in proportion to the length of time of the immersion in the simulated oral fluid. Mechanical strength of a denture base repaired with a round joint design and light-cured material is significantly higher after immersion in simulated oral fluid. [source] Mechanical and corrosion properties of spot-welded high-strength austenitic stainless steel EN 1.4318MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 4 2008M. T. Alenius Abstract Mechanical and corrosion properties of spot-welded high-strength austenitic stainless steels EN 1.4318 2H/C1150 and EN 1.4318 2H/C850 were studied. Microhardness measurements, lap shear and cross-tension tests, corrosion fatigue tests and corrosion tests were carried out. The corrosion environment was 3.5% sodium chloride solution at +50,°C in the corrosion fatigue tests and 3.5% sodium chloride solution at ambient temperature in the electrochemical pitting corrosion tests. Stainless steel EN 1.4318 2H/C850, t,=,1.92 mm, exhibited better fatigue endurance than EN 1.4318 2H/C1150, t,=,1.2 mm, and EN 1.4318 2H/C850, t,=,1.0 mm, stainless steels did. There were no significant differences between the stainless steels of different strength levels (2H/C850 vs. 2H/C1150) in the line load range analysis of the fatigue data. High hardness gradient was found in the heat-affected zone (HAZ) of EN 1.4318 2H/C1150 stainless steels. EN 1.4318 2H/C1150, t,=,1.2 mm, stainless steels seemed to have slightly higher lap shear strength with the same nugget diameter as EN 1.4318 2H/850, t,=,1.9 mm, stainless steel. In the case of EN 1.4318 2H/C1150 stainless steel increase in the nugget diameter bigger than required 5,t did not increase the cross-tension force significantly. The pitting corrosion susceptibility of the spot-welded samples and the base materials of the steels EN 1.4318 2H/C850 and EN 1.4318 2H/C1150, t,=,1.2 mm, was investigated by measuring the corrosion current for 1 h at +100 mV versus saturated calomel electrode (SCE) in 3.5% sodium chloride solution at ambient temperature. Pitting corrosion occurred in all spot-welded samples but not in the base materials. There was a difference between the investigated steels in the location of the pits. In stainless steels EN 1.4318 2H/C850 the pits appeared around the spot weld, but in the steel EN 1.4318 2H/C1150, t,=,1.2 mm, the pits are located mainly at the spot-weld area. [source] In vitro adhesion of Candida species to denture base materialsMYCOSES, Issue 2 2006X. Y. He Summary Adhesion of Candida species to prosthetic acrylic resins is an essential first step in the pathogenesis of denture stomatitis. Data on the relative adhesion of pathogenic non- albicans Candida species to different denture base materials are sparse. The purpose of the present study was to investigate in vitro adhesion of C. albicans, C. glabrata, C. krusei and C. dubliniensis to four different denture base materials. Specimens of both heat-cured resins (VertexTM Rapid Simplified and ProBaseTM Hot) and cold-cured resins (Paladur® A and Paladur® B) were prepared using a novel method and the adhesion of four strains each of the foregoing Candida species evaluated microscopically using a soft imaging system. There was a significant difference in yeast adherence between Vertex and the other resins. Only C. glabrata attached to Vertex, while all the remainder of the tested species adhered to all other resins tested except ProBase, which resisted C. krusei adhesion. There was a significant difference in candidal adhesion between cold-cured and heat-cured resins for three Candida species (C. albicans, P = 0.039; C. glabrata, P = 0.002 and C. krusei, P = 0.000). The type of denture base material and whether they are heat-cured or cold-cured play an important role in modifying candidal adhesion. [source] Effects of welding procedures on mechanical and morphological properties of hot gas butt welded PE, PP, and PVC sheetsPOLYMER ENGINEERING & SCIENCE, Issue 4 2008Onur Balkan Mechanical and morphological properties of hot gas butt welds on polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) sheets for four different procedures, which are single and double V-welds with and without a welding shoe, were investigated. Besides, weldabilities of base materials were evaluated by rheological measurements. These revealed that weldabilities of PE and PP sheets were better than that of PVC. Welding energy (Ew), which is transferred onto weld surfaces, was calculated to evaluate weld quality. The results of tensile, impact, and bending tests indicated that the weld strengths of PVC sheets were lower than those of PE and PP sheets. When the welding shoe was used, weld strength increased significantly for each material because of the presence of sufficient welding pressure and the effective heating on surfaces. The best results were attained for the double V-welds with the welding shoe. Morphology of welded regions was evaluated by polarized light, stereo, and scanning electron microscopy. Polarized light microscopy studies indicated that the heat-affected zone (HAZ) consisted of welding rod core, molten zone, and deformed spherulitic zone, and the welding interface was indistinguishable from the base material when the welding pressure was enough. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Haze of polyethylene films,effects of material parameters and clarifying agentsPOLYMER ENGINEERING & SCIENCE, Issue 5 2002Erik Andreassen Effects of material parameters on the haze of blown films were analyzed. Four linearlow-density polyethylenes (two metallocene grades and two Ziegler-Natta grades) were studied in combination with three additives (two sorbitol-based clarifying agents and a low-molecular-weight long-chain branched polyethylene). One of the sorbitol-based additives reduced the haze of both the metallocene materials in this study, but did not have any positive effect on the two Ziegler-Natta materials. The variation in haze among the four base materials was directly related to the root-mean-square surface roughness (,). When considering all 16 material/additive combinations, the link between haze and surface topography was not a simple ,-haze relationship, but the haze was correlated with the average distance between adjacent surface profile peaks, the average slope, and the power spectral density at high lateral frequencies. Both of the mechanisms referred to in the literature, extrusion-induced haze and crystallization-induced haze, were probably active for the films in this study. [source] | |||||||||||||||||||||||||||||||