Showing papers in "Advanced Materials Research in 2009"
TL;DR: It is demonstrated that the fluorescence silica nanoprobe biomarker will have been potential for rapid diagnosis applications on plant diseases.
Abstract: Fluorescent silica nanoprobe as a biomarker for detection has attracted much attention in the field of nano-biotechnology recently but no further research applications using fluorescent silica nanoparticles (FSNP) combined with antibody molecules reported to detect pathogen detection. In this study, silica nanoparticles were prepared using the water-in-oil (w/o) microemulsion method. The silica nanoparticles were circular in diameter of 50 ± 4.2 nm. The organic dye, tris-2, 2' -bipyridyl dichlororuthenium (II) hexahydrate (Rubpy), could be incorporated efficiently into the core of silica nanoparticles. The fluorescence of Rubpy-doped silica nanoparticles was photostable using a collisional quenching fluorescence test. The Rubpy-doped silica nanoparticles were conjugated with the secondary antibody of goat anti-rabbit immunoglobulin G (IgG) and successfully detected plant pathogen such as Xanthomonas axonopodis pv. vesicatoria that causes bacterial spot disease in Solanaceae plant. These results demonstrated that the fluorescence silica nanoprobe biomarker will have been potential for rapid diagnosis applications on plant diseases.
116 citations
TL;DR: In this article, the authors reviewed three-dimensional printing for generation of prototype for casting applications and revealed that the time and cost of developing new foundry tools could be greatly reduced.
Abstract: Rapid prototyping (RP) is being widely used in diverse areas, from the building of aesthetic and functional prototypes to the production of tools and moulds for prototypes. Many RP techniques like stereo lithography, laminated object manufacturing, three dimensional printing etc. are commercially available. The implication of these technologies revealed that the time and cost of developing new foundry tools could be greatly reduced. The purpose of the present research paper is to review three dimensional printing for generation of prototype for casting applications.
62 citations
TL;DR: Bioleaching the biooxidised e-waste significantly improved gold recovery, especially by C. violaceum, particularly at high pulp density, and the ratio of gold/copper in leachates after bioleaching of theBiooxidized e-Waste was also found to be increased.
Abstract: This work compares gold bioleaching from e-waste containing gold and copper by Chromobacterium violaceum and Pseudomonas fluorescens. The effect of pulp density (ranging from 0.5 to 8%w/v) was examined. Although C. violaceum produced more cyanide than P. fluorescens in the absence of e-waste, P. fluorescens showed higher growth rate, cyanide production and gold leaching efficiency at all pulp densities. Pretreatment with biooxidation of the e-waste using Acidithiobacillus ferrooxidans resulted in the removal in excess of 80% of the copper present in the waste, and increased the gold/copper ratio in the residual solid. Bioleaching the biooxidised e-waste significantly improved gold recovery, especially by C. violaceum, particularly at high pulp density. For example, at pulp densities of 2 and 4% w/v, gold recovery from non-biooxidzed e-waste was 0.22 and 0.14% respectively. Higher gold recovery, at 8%, was obtained for bioleaching of the biooxidised e-waste at both these pulp densities. The ratio of gold/copper in leachates after bioleaching of the biooxidized e-waste was also found to be increased.
51 citations
TL;DR: In this paper, the effect of bagasse ash (BA) admixture on the engineering properties of lime treated black cotton soil was carried out and the results obtained show that the moisture density relationship follows a trend of increasing optimum moisture content (OMC)/decreasing maximum dry density (MDD) at the Standard Proctor compaction energy.
Abstract: Laboratory studies to investigate the effect of Bagasse Ash (BA) admixture on the engineering properties of lime treated black cotton soil was carried out. Black cotton soil is classified as A-7-6 or CH respectively. Bagasse ash is obtained from burning the fibrous residue from the extraction of sugar juice from sugarcane. The results obtained show that the moisture density relationship follows a trend of increasing optimum moisture content (OMC)/decreasing maximum dry density (MDD) at the Standard Proctor compaction energy. California bearing ratio (CBR) values obtained are lower than the 80% CBR criterion for untreated base course materials. The peak CBR value obtained was 31% at 8 %lime/ 4%BA. This value meets the recommended criteria for subgrade materials. The Unconfined compressive strength (UCS) at 7 days is lower than the 1034.25kN/m2 evaluation criterion for adequate lime stabilization. On the basis of the soaked CBR and durability values, it is recommended that black cotton soil can be stabilized for road construction using a 8 % lime/ 4 % BA blend of admixture at standard proctor compaction. However, due to the relative high cost of lime and large quantity that shall be required to achieve stabilization, further study and consideration should therefore be given to the use another additive such as cement to augment and lower the percentage of lime and thus the cost of stabilization.
45 citations
TL;DR: In this paper, the effect of the main process parameters (laser power, scan speed, scan spacing, hatch spacing, scanning strategy) and of thermal treatments on the quality of built parts in terms of hardness, density, microstructure, and mechanical properties was investigated.
Abstract: Selective Laser Sintering (SLS), has become one of the most popular technique in the layer manufacturing processes because of the ability to build complex geometries models with a wide range of materials. Recently, the interest in SLS is mainly focused into metals because of the possibility of producing models not only for the prototyping step but also as functional parts. Driven by the need to process nearly full dense objects, with mechanical properties comparable to those of bulk materials and by the desire to avoid long post processing cycles, Selective Laser Melting (SLM) has been developed. SLM represents an evolution of the SLS process: in the first one the complete melting of powder occurs rather than sintering or partial melting of the second one. SLM, is mainly suitable to produce tools and inserts with internal undercuts and channels for conformal cooling for injection molding. A careful control of the parameters which influence the melting and the amount of energy density involved in the process is necessary to get parts with optimized quality. The aim of this paper was to study the effect of the main process parameters (laser power, scan speed, scan spacing, hatch spacing, scanning strategy) and of thermal treatments on the quality of built parts in terms of hardness, density, microstructure, and mechanical properties. The 18 Ni Marage 300 steel, one of the most used materials in the die industry was investigated, using a Nd:YAG laser with a maximum power of 100W.
38 citations
TL;DR: In this article, the authors evaluated kinetic and adsorption physicochemical models for the biosorption process of lanthanum, neodymium, europium, and gadolinium by Sargassum sp.
Abstract: This work evaluated kinetic and adsorption physicochemical models for the biosorption process of lanthanum, neodymium, europium, and gadolinium by Sargassum sp. in batch systems. The results showed: (a) the pseudo-second order kinetic model was the best approximation for the experimental data with the metal adsorption initial velocity parameter in 0.042-0.055 mmol.g-1.min-1 (La
34 citations
TL;DR: In this article, a novel way to describe the complexity of biological and engineering approaches depending on the number of different base materials is proposed: either many materials are used (material dominates) or few materials (form dominates), or just one material (structure dominates).
Abstract: A novel way to describe the complexity of biological and engineering approaches depending on the number of different base materials is proposed: Either many materials are used (material dominates) or few materials (form dominates) or just one material (structure dominates). The complexity of the approach (in biology as well as in engineering) increases with decreasing number of base materials. Biomimetics, i.e., technology transfer from biology to engineering, is especially promising in MEMS development because of the material constraints in both fields. The Biomimicry Innovation Method is applied here for the first time to identify naturally nanostructured rigid functional materials, and subsequently analyse their prospect in terms of inspiring MEMS development.
33 citations
TL;DR: In this paper, the microstructure and electrical properties of the varistor ceramics were studied by a solid reaction route, and the results showed with addition of 0-1.00mol% La2O3 and 0.08mol% ZnO-based varistor Ceramics exhibit comparatively ideal comprehensive electrical properties such as the threshold voltage was 320V/mm, the nonlinear coefficient was 36.8 and the leakage current was 0.29μA.
Abstract: La2O3-doped ZnO-Bi2O3-based varistor ceramics were obtained by a solid reaction route, and the microstructure and electrical properties of the varistor ceramics were studied in this paper. The results showed with addition of 0-1.00mol% La2O3, La2O3-doped ZnO-based varistor ceramics were prepared in this paper with the voltage gradient of 77-503V/mm, the nonlinear coefficient of 2.4-36.8, and the leakage current of 0.09-494μA. The results also showed with addition of 0.08mol% La2O3, La2O3-doped ZnO-based varistor ceramics exhibit comparatively ideal comprehensive electrical properties. Such as the threshold voltage was 320V/mm, the nonlinear coefficient was 36.8 and the leakage current was 0.29μA. The doping of La2O3 affects the form and decomposition of the pyrochlore.
30 citations
TL;DR: The potential of periwinkle shell as coarse aggregate for concrete was studied in this article, where concrete cubes were made and tested at hydration periods of 7, 14, 21 and 28 days.
Abstract: The potential of periwinkle shell as coarse aggregate for concrete was studied in this paper. The properties of concrete made with periwinkle shell as coarse aggregate were examined. Test conducted on the concrete was compressive strength test. Prescribed mix designs of 1:1:2, 1:2:3, 1:4:6, 1:2:4 and 1:3:5 were used to produce concrete cubes used for testing. The different constituents that make up the periwinkle concrete are presented in ratio form as cement: sharp Sand: Periwinkle shell. Batching was done by volume and the corresponding weight recorded. The cubes were made and tested at hydration periods of 7, 14, 21 and 28 days to determine the compressive strength of the periwinkle shell concrete. The results show that periwinkle shell has a bulk density of 517kg/m3 and specific gravity of 2.05. The results also shows that design mix of 1:1:2, 1:2:3 and 1:2:4 with compressive strength of 25.67 N/mm2, 19.50N/mm2 and 19.83N/mm2 at 28 days hydration period respectively met the ASTM-77 recommended minimum strength of 17N/mm2 for structural light weight concrete while mix design of 1:4:6, and 1:3:5 with compressive strength of 14.00N/mm2 and 16.50N/mm2 respectively did not met the standard.
27 citations
TL;DR: The 16S rDNA analysis showed that most of the cultivated Fe(II)-oxidizers belong to four genera: Acidithiobacillus, Acidimicrobium, “FerrimicroBium” and Leptospirillum, and several strains related to Acidiphilium acidophilum have been detected and form one 16SrDNA cluster.
Abstract: More than 100 cultures of acidophilic Fe(II)- and/or sulfur-oxidizing microorganisms from mine waste dumps in 10 different countries all over the world have been maintained in liquid media in the BGR-strain collection for many years. Our 16S rDNA analysis showed that most of the cultivated Fe(II)-oxidizers belong to four genera: Acidithiobacillus, Acidimicrobium, “Ferrimicrobium” and Leptospirillum. All analyzed Acidithiobacillus strains were identified as At. ferrooxidans. The Leptospirillum strains were affiliated with L. ferriphilum or L. ferrooxidans. The Gram-positive strains related to Acidimicrobium or ”Ferrimicrobium” were phylogenetically more diverse than the strains of the genera Acidithiobacillus and Leptospirillum and fell into three separate clusters. While several strains could be identified as syngeneic (16S rDNA) with “Ferrimicrobium acidiphilum”, two other 16S rDNA clusters were distantly related and might represent new species or even new genera. In addition, one new Sulfobacillus strain and one new Alicyclobacillus strain could be identified. Furthermore several strains related to Acidiphilium acidophilum have been detected and form one 16S rDNA cluster.
26 citations
TL;DR: In this article, a simple and easily understandable model was proposed for predicting the relative importance of different factors (composition of the steels and Electro Discharge Machining processing conditions) in order to obtain an efficient pieces.
Abstract: Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and an electrode. There are various types of products which can be produced by using the EDM such as dies and moulds. Today many parts used in aerospace and automotive industry and also final processes of surgical components can be finished by EDM process. A simple and easily understandable model was proposed for predicting the relative importance of different factors (composition of the steels and Electro Discharge Machining processing conditions) in order to obtain an efficient pieces. A detail application on the tool steels machined by EDM was given in this study. This model is based on thermal, metallurgical and mechanical and also in situ test conditions. It gives detail information on the effect of electrochemical parameters on the surface integrity and sub-surface damage of the material (Heat Affected Zone, HAZ), the level of residual stresses, and the surface texture. This approach is an efficient way to separate the responsibilities of the steel maker and machining process designer for increasing the reliability of the machined structures.
TL;DR: Bioremediation can be applied for the treatment of metal/metalloid and radionuclide bearing water streams in order to immobilize the targeted species and bioprecipitation and bioreduction are the basis of technologies for the rehabilitation of contaminated sites.
Abstract: Bioremediation can be applied for the treatment of metal/metalloid and radionuclide bearing water streams in order to immobilize the targeted species. Interactions of microbial cells with soluble targeted species may occur during the microbial metabolism and result to the reduction of their mobility and toxicity. The most important metabolically mediated immobilization processes for metal/metalloid and radionuclide species are bioprecipitation and bioreduction. Bioprecipitation includes the transformation of soluble species to insoluble hydroxides, carbonates, phosphates and sulfides as a result of the microbial metabolism. In the case of biological reduction, the cells use the species as terminal electron acceptors in anoxic environments to produce energy and/or reduce the toxicity of the cells microenvironment. These processes can be the basis of technologies for the rehabilitation of contaminated sites both for surface and groundwater aquifers, soils and industrial water streams. Such technologies are recently developed and applied both in pilot and full scale, although the related mechanisms are complicated and not always fully understood.
TL;DR: In this article, a review of these options in relation to the degree of grain refinement in ferritic stainless steel weld is conducted in order to have a better understanding about the grain refining phenomenon in the weld microstructure.
Abstract: The ferritic stainless steel is a low cost alternative to the most often adopted austenitic stainless steel due to its higher strength, better ductility and superior corrosion resistance in caustic and chloride environments. However, the application of ferritic steel is limited because of poor ductility and notch impact toughness of its weld section with differential grain structures. Several techniques have been explored to control the grain features of the weld to minimize these problems. In the present effort, a review of these options in relation to the degree of grain refinement in ferritic stainless steel weld is conducted in order to have a better understanding about the grain refining phenomenon in the weld microstructure. So far, the most effective technique is found to be the pulse AC TIG welding which can produce weld with mechanical properties equivalent to 65% to those of the base metal. The refinement in this process occurred through dendrite fragmentation and grain detachment in the weld pool producing small-grained microstructures with a large fraction of equiaxed grains. However, in friction welding process where heat input and heat transfer are effectively controlled, the strength can be as high as 95% of the parent metal. This suggests that the total energy input for welding and heat transfer phenomenon mainly control the development of microstructural feature in the weld pool and hence the strength.
TL;DR: The extensive dissolution of pyrite during autotrophic growth contrasted with a requirement for yeast extract for significant growth of the related Acidimicrobium ferrooxidans.
Abstract: Novel iron- and sulfur-oxidizing, moderate thermophiles were isolated from an acidic geothermal site and from a previously studied, pyrite-enrichment mixed culture (which also contained the related actinobacterium Acidimicrobium ferrooxidans). The novel species (proposed genus “Acidithiomicrobium”) grew autotrophically with ferrous iron at an optimum temperature of about 50°C, efficiently degraded pyrite at 55°C and also grew well autotrophically on sulfur. The extensive dissolution of pyrite during autotrophic growth contrasted with a requirement for yeast extract for significant growth of the related Acidimicrobium ferrooxidans.
TL;DR: In this article, a study on 120 MeV Ag9+ irradiated thin films of zinc oxide (ZnO), obtained by sol-gel spin coating onto TCO glass plates, was conducted.
Abstract: This paper deals with a study on 120 MeV Ag9+ irradiated thin films of zinc oxide (ZnO), obtained by sol-gel – spin coating onto TCO glass plates. Films irradiated at fluence 5×1011, 3×1012, 5×1012 and 2×1013 ions cm-2, were optically characterized for band gap determination. XRD analysis revealed polytypism as both wurtzite and zincblend phases co-evolved. Scherrer’s calculations indicated grain size in nanodimensions, while SEM analysis indicated smooth surface morphology of films. Flat band potentials and donor densities were evaluated by Mott-schottky calculations. For PEC studies, thin films of ZnO were employed as working electrode in conjunction with Platinum Counter electrode, Saturated Calomel Reference electrode, 13 pH aqueous solution of NaOH as electrolyte and 150W Xenon Arc light source for illumination. A significant gain in photoelectrochemical current was recorded on SHI irradiation. The films irradiated at fluence 3×1012 ions cm-2 yielded maximum increase in photocurrent that was nearly five times compared to unirradiated samples.
TL;DR: In this article, a maximum dimensionless figure of merit of 0.8 was obtained for the Bi-doped Mg2Si nanocomposite with 50 wt % nanopowder inclusions at 823K, about 63% higher than that of Bi-druged Mg 2Si sample without nanopowder and 119% higher higher than micro-sized Mg 1.5Si sample with inclusions, respectively.
Abstract: Nanocomposites and heavy doping both are regarded as effective way to improve materials’ thermoelectric properties. 0.7at% Bi-doped Mg2Si nanocomposites were prepared by spark plasma sintering. Results of thermoelectric properties tests show that the doping of Bi atom effectively improves the electrical conductivity of Mg2Si，and the nanocomposite structures are helpful to reduce thermal conductivity and increase Seebeck coefficient, hence improving the thermoelectric performance. A maximum dimensionless figure of merit of 0.8 is obtained for the Bi-doped Mg2Si nanocomposite with 50 wt % nanopowder inclusions at 823K, about 63% higher than that of Bi-doped Mg2Si sample without nanopowder inclusions and 119% higher than that of microsized Mg2Si sample without Bi-doped, respectively.
TL;DR: The concept of functional bionanomaterials is introduced in this paper, where waste treatment along with nanocatalysis or other applications can be summarized as Environmental Bionanotechnology.
Abstract: Over the past 30 years the literature has burgeoned with bioremediation approaches to heavy metal removal from wastes. The price of base and precious metals has dramatically increased. With the resurgence of nuclear energy uranium has become a strategic resource. Other ‘non-carbon energy’ technologies are driven by the need to reduce CO2 emissions. The ‘New Biohydrometallurgy’ we describe unites these drivers by the concept of conversion of wastes into new materials for environmental applications. The new materials, fashioned, bottom-up, into nanomaterials under biocontrol, can be termed ‘Functional Bionanomaterials’. This new discipline, encompassing waste treatment along with nanocatalysis or other applications, can be summarized as ‘Environmental Bionanotechnology’. Several case histories illustrate the scope and potential of this concept.
TL;DR: In this article, the effects of fiber volume fraction on mechanical properties and macroporosity, and the biocompatibility of a calcium phosphate cement (CPC)-fiber composite were investigated.
Abstract: Calcium phosphate cement (CPC) sets in situ to form solid hydroxyapatite, can conform to complex cavity shapes without machining, has excellent osteoinductivity, and is able to be resorbed and replaced by new bone. Therefore, CPC is promising for craniofacial and orthopaedic repairs. However, its low strength and lack of macroporosity limit its use. This study investigated CPC reinforcement with absorbable fibers, the effects of fiber volume fraction on mechanical properties and macroporosity, and the biocompatibility of CPC-fiber composite. The liquid phase of CPC in this study was the weak acidic solution of chitosan. Chitosan has favourable biocompatibility, which has high viscosity in solution. The incorporation of chitosan could improve the handling properties of CPC. The liquid phase contained citric acid could strongly improve the hydration rate of CPC, which shortened the setting time and increased the compressive strength of CPC. In addition, the weak acidic environment around the biomaterials could accelerate the degradation of CPC, which was important to bone tissue engineering. The rationale was that large-diameter absorbable fibers would initially strengthen the CPC graft, then dissolve to form long cylindrical macropores for colonization by osteoblasts. Compressive strength was measured vs. fiber volume fraction from 0% (CPC Control without fibers) to 70%. Animal experiment showed that the material had osteoinductivity and biodegradability when the material was implanted into the muscle pouches in the thigh of rabbits. Compressive strength (mean ± SD; n=3) of CPC with 70% fibers was 0.8± 0.1 MPa. Long cylindrical macropores 100~300 μm in diameter were created in CPC after fiber dissolution, and the CPC-fiber scaffold reached a total porosity of 75.1±1.2% with 70% fibers. The new CPC-fiber formulation had good potentiality of ectopic bone induction. The method of using large-diameter absorbable fibers in bone graft for mechanical properties and formation of long cylindrical macropores for bone ingrowth may be applicable to other tissue engineering materials.
TL;DR: A brief review of some of the key aspects of abrasive polishing, including adaptability and sustainability of artificial materials to human body, selection of materials, precision fabrication and efficient replacement operation are provided.
Abstract: To produce lifelong, harmless hip joint prostheses, considerable cross-disciplinary studies have been carried out. The research includes adaptability and sustainability of artificial materials to human body, selection of materials, precision fabrication and efficient replacement operation. This paper provides a brief review of some of these key aspects with some details in abrasive polishing.
TL;DR: In this article, a stable and homogeneneous aqueous suspension of carbon nanotubes was prepared and the stability of the nanofluids was improved greatly due to the use of a new dispersant.
Abstract: The stable and homogeneneous aqueous suspension of carbon nanotubes was prepared in this study. The stability of the nanofluids was improved greatly due to the use of a new dispersant, humic acid. The thermal conductivity of the aqueous suspension was measured with the 3ω method. The experimental results showed that the thermal conductivity of the suspensions increases with the temperature and also is nearly proportional to the loading of the nanoparticles. The thermal conductivity enhancement of single-walled carbon nanotubes (SWNTs) suspensions is better than that of the multi-walled carbon nanotubes (MWNTs) suspensions. Especially for a volume fraction of 0.3846% SWNTs, the thermal conductivity is enhanced by 40.5%. Furthermore, the results at 30°C match well with Jang and Choi’s model.
TL;DR: In this paper, the effect of xenon-arc light irradiation with water spray on the changes in color, thickness and mechanical properties of reconstituted bamboo lumber was investigated.
Abstract: Reconstituted bamboo Lumber suffers surface and mechanical properties degradation after exposure to outdoor environment. In this paper, Neosinocalamus affinis bamboo bundles was selected to thermo-treated at three temperature levels (160,180 and 200°C) for 2 hours and investigated the effect of xenon-arc light irradiation with water spray on the changes in color, thickness and mechanical properties of reconstituted bamboo lumber. The results indicated that the surface color of the samples changed rapidly during the irradiation process and the change rate decreased as the increasing of thermo-treated temperature. The mechanical properties analysis indicated that MOE wasn’t much affected by the thermo-treated and artificial weathering test, whereas MOR and shear strength decrease after exposure. The thickness swelling after exposure was improved by the thermo-treatment and decreased as the treated temperature increased.
TL;DR: All TiO2 nanomaterial groups had no effect on lives’ morphology and oxidative stress, with no obvious histopathological changes observed in heart, lung, liver and kidney, and these tissues presented no vacuolar degeneration, necrosis edema, engorgement and inflammation.
Abstract: TiO2 nanomaterials with different dimensions(zero and one), sizes(20nm, 50nm and 100nm in diameter) and crystal structures(100% rutile, 100% anatase and combination of 20% rutile and 80% anatase) were confected to suspensions and ointment with varied concentrations and evaluated in animal model (Balb-c mouse). These mouse were divided into various groups randomly, with suspension intraperitoneally injected or ointment transdermally daubed. Heart, lung, liver and kidney were collected and prepared to HE sample after one week. Spectrophotometry was applied to study total antioxide capability and catalase activity of blood and tissues. It has been shown that all TiO2 nanomaterial groups had no effect on lives’ morphology and oxidative stress, with no obvious histopathological changes observed in heart, lung, liver and kidney, and these tissues presented no vacuolar degeneration, necrosis edema, engorgement and inflammation.
TL;DR: The combined biologically performed technology of phosphorus leaching and separation from toxic metals by simultaneous bioaccumulation developed in this study is a promising process for economical and ecological recovery of phosphorus from waste solids.
Abstract: The recovery of phosphorus from sewage sludge incineration ash as well as the separation of heavy metals from ash was investigated by using the biotechnological process of bioleaching and bioaccumulation of released phosphorus by newly developed population of bioleaching bacteria, Acidithiobacillus sp. strains, and polyphosphate (poly-P) accumulating bacteria, the AEDS-population (Acidithiobacillus sp. enriched digested sludge). The biologically performed solubilization of phosphorus from sewage sludge incineration ash is accompanied by the release of toxic metals. Therefore a combined process to separate phosphorus from heavy metals by achieving a plant available phosphorus-enriched product and a metal depleted ash was designed. Leaching experiments were conducted in laboratory scaled leaching reactor containing a bacterial stock culture of Acidithiobacillus sp.. Next step was the enhancement of P-recovery in combining bioleaching with simultaneous bio-P-accumulation by AEDS-population. The uptake of phosphorus in biomass reaches up to 66 % of the mobilized phosphorus by bioleaching. The combined biologically performed technology of phosphorus leaching and separation from toxic metals by simultaneous bioaccumulation developed in this study is a promising process for economical and ecological recovery of phosphorus from waste solids.
Abstract: In this paper, 2.5D SiO2f/SiO2 composites were fabricated via sol-gel process employing 2.5D braided silica fiber fabrics as reinforcements and high pure silicasol as slurry. The process parameters are optimized and the optimal parameters are as follows: the silicasol of 30.8 wt. % as slurry, microwave drying, and sintering at 900 °C. Utilizing the optimal process parameters, the density and the flexural strength of the composites can reach 1.65 g•cm-3 and 80.68 MPa respectively. Dielectric properties of the 2.5D SiO2f/SiO2 composites were also measured, and the real part of the permittivity is 3.40 at 5 GHz. The excellent mechanical and dielectric properties of the 2.5D SiO2f/SiO2 composites can well meet the requirements of radome materials.
TL;DR: In this paper, the authors studied the effect of high-temperature oxidation on cracks in Al2O3 composites toughened by Ni nanoparticles and showed that crack disappearance depends on both annealing temperature and time.
Abstract: Crack disappearance by high-temperature oxidation was studied in alumina (Al2O3) composites toughened by Ni nanoparticles. This process is performed in air at temperature ranging from 1000 to 1300°C for 1 to 48 h. The results showed that crack disappearance depends on both annealing temperature and time. Complete crack disappearance in this composite was confirmed at lower temperatures for long oxidation period, 1100oC for 48 h, and higher temperature for shorter time, 1300oC for 1 h in air. The crack disappearance mechanism was explained on the basis of the formation of NiAl2O4 spinel on sample surfaces produced by the oxidation reaction during the heat treatment.
TL;DR: In this article, the compounding of rice husk and high density polyethylene (HDPE) was undertaken on a Sino PSM 30 co-rotating twin screw extruder.
Abstract: The compounding of rice husk and high density polyethylene (HDPE) was undertaken on a Sino PSM 30 co-rotating twin screw extruder. Four sizes of rice husk were studied at various compositions. The size ranged from 500 μm and below (coded A, B, C and D) while the content of rice husk in the composite varies from 30, 40 and 50 percent of weight. A fixed amount of Ultra-Plast TP10 as a compatibilizer and Ultra-Plast TP 01 as lubricant, were added into the bio-composite compound. The injection molding process ability of the bio-composite was studied through flow behavior on melt flow indexer and analyzed on JSW N100 B11 Injection Molding. Size A which has the largest particle is the most appropriate size as the bio-composite filler based on thermal stability test. The melt flow rate of rice husk/HDPE (RHPE) decreases with the increased in rice husk compositions and apparent viscosity also increases with composition for all filler size. Melt flow rate above 4g/10 min was found to be the lower limit for injection molding process. The smaller the filler size, the lower is the impact strength and the increased in the filler composition lowers the impact strength. A bio-composite at 30 weight percent rice husk size A (RH30PEA) was found to have optimum rheological properties with respect to impact strength.
TL;DR: In this paper, an acidic saline drain in the Western Australian wheat belt was sampled and enriched for salt tolerant chemolithotrophic microorganisms in acidic media containing up to 100 gL-1 NaCl.
Abstract: In this study an acidic saline drain in the Western Australian wheat belt was sampled and enriched for salt tolerant chemolithotrophic microorganisms in acidic media containing up to 100 gL-1 NaCl. A mixed consortium was obtained which grows at pH 1.8 and oxidises iron (II) in the presence of up to 30 gL-1 NaCl. In comparative tests (growth rates and iron (II) oxidation rates) it was found that NaCl concentrations >3.5 gL-1 generally cause reduced growth and iron (II) oxidation rates in known biomining organisms. The results help to set a benchmark for NaCl tolerance in known biomining microorganisms and will lead to the generation of a consortium of microorganisms that can oxidise iron (II) effectively in saline process water.
TL;DR: Biosulfidogenesis (the generation of hydrogen sulfide by microorganisms) in acidic liquors was investigated using two metabolically-distinct bacteria, and the potential of using acidophilic sulfidogens for the selective recovery of metals from acidic waste streams is discussed.
Abstract: Biosulfidogenesis (the generation of hydrogen sulfide by microorganisms) in acidic liquors was investigated using two metabolically-distinct bacteria. One was a novel acidophilic sulfate-reducing bacterium (isolate CL4) that grew at pH 3.0 and above using glycerol as electron donor, and the other was the type strain of Acidithiobacillus ferrooxidans which was grown at pH 2.5 using hydrogen (derived from dissolution of metallic iron) as electron donor and elemental sulfur as electron acceptor. Both bacteria were grown in pH-controlled bioreactors. Isolate CL4 mediated the selective precipitation of zinc in situ, while the At. ferrooxidans bioreactor operated as an off-line system, generating hydrogen sulfide that precipitated copper in a separate reaction vessel. The potential of using acidophilic sulfidogens for the selective recovery of metals from acidic waste streams is discussed.
TL;DR: In this article, the authors compared the catalysts in different composition ratios with the grown deposits after CVD, and found that the optimum mol ratio between Fe and Sn is 6:0.1.
Abstract: Chemical vapor deposition, Catalyst, Carbon nanocoils, High efficient growth Abstract: Carbon nanocoils (CNCs) were prepared by thermal chemical vapor deposition (CVD) using a Fe and Sn containing solution as the catalyst predecessor. The solutions of Fe2(SO4)3/SnCl2, FeCl3/SnCl2 and Fe(NO3)3/SnCl2 with the mol ratios of 3:0.1 to 3:1 were used as catalysts. Comparing the catalysts in different composition ratios with the grown deposits after CVD, we found that the optimum mol ratio between Fe and Sn is 6:0.1. It is noted that the catalyst combination of Fe2(SO4)3 /SnCl2 obviously increases the quantity of the grown carbon deposits indicating that it has the largest catalytic activity among the three kinds of combinations. Large surface area of catalyst films formed by release of SO3 from the decomposition of Fe2(SO4)3 over the temperature of 480 °C is very good for the carbon nanocoils growth and the introduction of sulfide impurities are the key factors leading to the high efficient growth for carbon nanocoils. It is known that Fe-additions lead to the growth of carbon nanotubes or nanofibers, while Sn induces their helical growth and a little sulfur impurities may induce the efficient growth of carbon nanocoils.
TL;DR: In this article, two geometrically nonlinear finite plate elements incorporating piezoelectric layers are applied based either on first- or third-order transverse shear deformation theory.
Abstract: This paper deals with nonlinear finite element analysis of smart structures with integrated piezoelectric layers. Two geometrically nonlinear finite plate elements incorporating piezoelectric layers are applied based either on first- or third-order transverse shear deformation theory. Nonlinear strain-displacement relations are used that are valid for small strains and moderate rotations. Numerical tests are performed for the time histories of the tip displacement and sensor output voltage of a thin beam with a piezoelectric patch bonded to the surface.