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TiO2 Particles (tio2 + particle)
Selected AbstractsFabrication of Three-Dimensional Micro Photonic Crystals of Resin-Incorporating TiO2 Particles and their Terahertz Wave PropertiesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2007Weiwu Chen Three-dimensional (3D) photonic crystals with a diamond structure made from 40 vol% TiO2,acrylate dielectric composites were formed by means of a CAD/CAM micro-stereolithography system. The lattice constant of the diamond unit cell was 500 ,m and the forming accuracy was 10 ,m. The photonic band gap in the ,,X ,100, direction measured by terahertz-time-domain spectroscopy appeared at 280,360 GHz, which agreed fairly well with the band gap calculated by the plane wave expansion method. [source] A Novel Hybrid Method of Sol,Gel and Ultrasonic Atomization Synthesis and Piezoelectric Properties of SrBi4Ti4O15 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2008Zhijun Xu SrBi4Ti4O15(SBTi) powders were synthesized by a novel hybrid method of sol,gel and ultrasonic atomization. TiO2 particle was used as a starting material to replace other expensive soluble titanium salts. X-ray diffraction results showed that the pure-phase SBTi powders were obtained at 700°C for 2 h, which is much lower than the calcination temperature (800°,850°C) required in solid-state reactions. The ceramics sintered at 1100°C for 1 h exhibited 94.5% of relative density and a piezoelectric coefficient of 21 pC/N. The results showed that this hybrid method could lead to an attractive method for the industrial fabrication of SBTi materials. [source] Study of PET/PP/TiO2 microfibrillar-structured composites, part 1: Preparation, morphology, and dynamic mechanical analysis of fibrillized blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Wenjing Li Abstract The objective of this study was to manufacture and investigate a novel microfibrillar-reinforced material based on fibrillized blends of polyethyleneterephthalate (PET), polypropylene (PP), and TiO2 nanoparticles (300 nm and 15 nm in size). The uncompatibilized and compatibilized blends (polypropylene grafted maleic anhydride as compatibilizer) were extruded and subsequently cold-drawn into strands with a draw ratio of 10. The effects of compatibilizer and TiO2 particles on the structure and properties of drawn strands were investigated. Upon addition of compatibilizer, the preferential location of TiO2 particles shifted from the PET-dispersed phase to the PP matrix, which brought about different structures of the drawn strands. Differential scanning calorimetry study provided indications for a heterogeneous nucleation effect of the PET fibrils on the PP matrix and of the TiO2 particles on the PET fibrils. Dynamic mechanical analysis demonstrated that the mechanical properties of the drawn strands are strongly dependent on the strand structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] In vivo acute toxicity of titanium dioxide nanoparticles to mice after intraperitioneal injectionJOURNAL OF APPLIED TOXICOLOGY, Issue 4 2009Jinyuan Chen Abstract Because of its excellent optical performance and electrical properties, TiO2 has a wide range of applications in many fields. It is often considered to be physiologically inert to humans. However, some recent studies have reported that nano-sized TiO2 may generate potential harm to the environment and humans. In this paper the in vivo acute toxicity of nano-sized TiO2 particles to adult mice was investigated. Mice were injected with different dosages of nano-sized TiO2 (0, 324, 648, 972, 1296, 1944 or 2592 mg kg,1). The effects of particles on serum biochemical levels were evaluated at various time points (24 h, 48 h, 7 days and 14 days). Tissues (spleen, heart, lung, kidney and liver) were collected for titanium content analysis and histopathological examination. Treated mice showed signs of acute toxicity such as passive behavior, loss of appetite, tremor and lethargy. Slightly elevated levels of the enzymes alanine aminotransferase and aspartate aminotransferase were found from the biochemical tests of serum whereas blood urea nitrogen was not significantly affected (P <0.05). The accumulation of TiO2 was highest in spleen (P <0.05). TiO2 was also deposited in liver, kidney and lung. Histopathological examinations showed that some TiO2 particles had entered the spleen and caused the lesion of spleen. Thrombosis was found in the pulmonary vascular system, which could be induced by the blocking of blood vessels with TiO2 particles. Moreover, hepatocellular necrosis and apoptosis, hepatic fibrosis, renal glomerulus swelling and interstitial pneumonia associated with alveolar septal thickening were also observed in high-dose groups. Copyright © 2009 John Wiley & Sons, Ltd. [source] Treatment of low turbidity water by sweep coagulation using bentoniteJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2005Yun-Hwei Shen Abstract A novel strategy of sweep coagulation to treat low turbidity water is presented herein. Study findings demonstrated that an Na+ -saturated bentonite with medium cation exchange capacity (CEC) resulted in significant turbidity removal at a bentonite dosage of 30 mg dm,3. Bentonite dispersion with fully delaminated platelets tended to undergo a more porous type of coagulation with intense face-to-face interactions of platelets and effectively entrapped TiO2 particles in band-type structures. This type of coagulation usually results in a large volume of settled flocs with a fluffy structure and excellent turbidity removal efficiency for sweep coagulation. The sign and magnitude of electrical charge on TiO2 particles has a minor effect on the efficiency of sweep coagulation. Copyright © 2005 Society of Chemical Industry [source] Low-Temperature Atomic Layer-Deposited TiO2 Films with Low PhotoactivityJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2009Xinhua Liang Atomic layer deposition (ALD) has been successfully utilized for the conformal and uniform deposition of ultrathin titanium dioxide (TiO2) films on high-density polyethylene (HDPE) particles. The deposition was carried out by alternating reactions of titanium tetraisopropoxide and H2O2 (50 wt% in H2O) at 77°C in a fluidized bed reactor. X-ray photoelectron spectroscopy confirmed the deposition of TiO2 and scanning transmission electron microscopy showed the conformal TiO2 films deposited on polymer particle surfaces. The TiO2 ALD process yielded a growth rate of 0.15 nm/cycle at 77°C. The results of inductively coupled plasma atomic emission spectroscopy suggested that there was a nucleation period, which showed the reaction mechanism of TiO2 ALD on HDPE particles without chemical functional groups. TiO2 ALD films deposited at such a low temperature had an amorphous structure and showed a much weaker photoactivity intensity than common pigment-grade anatase TiO2 particles. [source] Synthesis and Optical Properties of Soluble Polyimide/Titania Hybrid Thin FilmsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 12 2006Chih-Ming Chang Abstract Summary: In this study high-refractive-index polyimide/titania hybrid optical thin films were successfully prepared using a sol-gel process combined with spin coating and multistep baking. The hybrid thin films were prepared from a soluble polyimide, a coupling agent, and a titania precursor. Transparent hybrid thin films can be obtained at TiO2 content as high as 40 wt.-%. The FE-SEM results suggest that the TiO2 particles in the hybrid thin films have diameters in the nanometer range. The thermal decomposition temperatures of the prepared hybrid materials are above those of the respective polyimide except for the highest TiO2 content hybrids. The refractive indices at 633 nm of the prepared hybrid thin films increase linearly from 1.66 to 1.82 with increasing TiO2 content. The excellent optical transparency, thermal stability, and tunable refractive index provide the potentials of the polyimide/titania hybrid thin films in optical applications. [source] Zeolite Encapsulation Decreases TiO2 -photosensitized ROS Generation in Cultured Human Skin Fibroblasts,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2006Biao Shen ABSTRACT Sunscreens protect skin against sunburn. However, studies have demonstrated that UV-irradiated sunscreen components such as titanium dioxide (TiO2) promote the photogeneration of reactive oxygen species (ROS). Because encapsulation of TiO2 within zeolites alters its photocatalytic activity, supra-molecular composites based on NaY zeolite hosts containing TiO2 guests were prepared, and the effects on ROS formation in cells under UVA-irradiation evaluated. DCFH-DA (2,,7,-dichlorofluorescein diacetate) was used as a profluorescent probe to monitor intracellular ROS. The detection of in-tracellular 2,,7,-dichlorofluorescein (DCF) fluorescence by confocal microscopy revealed that DCFH-DA was taken up, hydrolyzed and oxidized by yeast cells and cultured human skin fibroblasts within 20 and 6 min, respectively. Higher DCF fluorescence was observed in fibroblasts following UVA irra-diation in the absence but not in the presence of the radical nitroxide, TEMPOL (4-hydroxy-2,2,6,6-tetramethylpipery-dine-1-oxyl), which exhibits superoxide dismutase-mimetic and catalase-mimetic activity. UVA-induced fluorescence increased by -50% in the presence of 32-nm anatase TiO2 particles and decreased by essentially an equal amount in the presence of TiO2 encapsulated within NaY zeolites (TiO2@NaY). Addition of the uncomplexed NaY host also decreased (by ,30%) the amount of UVA-induced fluorescence but, un-expectedly, the combination of the free guest and host (TiO2@NaY) caused a doubling of the fluorescence. Protection of cells against TiO2 -induced intracellular ROS by encapsulation suggests that supramolecular species may be beneficial in photoprotection of the skin. In contrast, the potentiation of TiO2 -induced ROS by uncomplexed NaY points to a critical role for formulation when free TiO2 is used as a sun screen ingredient. [source] The structure of trititanate nanotubesACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2002Q. Chen A comprehensive chemical and structural analysis is made of a new type of trititanate nanotube, which is synthesized via the reaction of TiO2 particles with NaOH aqueous solution. It is found that the trititanate nanotubes are multi-walled scroll nanotubes with an inter-shell spacing of about 0.78,nm and an average diameter of about 9,nm. An atomic model of the nanotube is derived based on information from powder X-ray diffraction, selective-area electron diffraction, high-resolution electron microscopy and structure simulations. A model nanotube may be constructed by wrapping a (100) sheet of H2Ti3O7 along [001] with the tube axis parallel to [010]. [source] Separation and Mineralogical Analysis of Bayer Red MudASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2002T. Picaro This paper describes preliminary work to assess the potential for recovering valuable components from Queensland Alumina Limited (QAL) red mud by physical beneficiation. Upgrading of Weipa bauxites residue was trialed using a 50 mm hydrocyclone and a Mozley Multigravity Separator (MGS) to recover desilication product (DSP) and TiO2 fractions. The mineralogy of the original red muh and the various sub-fractions produced was studied by chemical assay, selective leaching, XRD and SEM techniques. DSP is present in QAL red mud in two forms: (i) as balls in the size range from 0.8 to 10 ,m that appear to be liberated; and (ii) as finely grained DSP intermixed with the other minerals. The hydrocycloning tests produced a DSP rich (39.5 wt%) fraction at 89% recovery from a feed containing 31.9 wt.% DSP. This represents an upgrade (enrichment) of 1.24 times. These results suggest that the greatest DSP enrichment will be achieved by targeting the 0.8 to 10 ,m DSP balls. The richest TiO2 fraction produced varied from 20 to 36 wt.% TiO2 from a feed value of 7 wt.% at a recovery of 7.5%. Mineralogical examination showed that most of the TiO2 in this fraction was as liberated particles in the size range 8 to 20 ,m. Most of the TiO2 particles in the other fractions were not fully liberated from mainly iron minerals. The present work indicates that it is possible to further upgrade DSP fractions by investigating finer particle separation techniques, e.g. smaller, 25 mm and 10 mm, hydrocyclones. [source] Heterometal Alkoxides as Precursors for the Preparation of Porous Fe, and Mn,TiO2 Photocatalysts with High EfficienciesCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2008Xiao-Xin Zou Abstract Transition-metal-doped titanium glycolates (M,TG, with M=Fe, Mn), which are the first non-stoichiometric heterometal alkoxides, have been synthesised through a solvothermal doping approach. X-ray diffraction, UV/Vis diffuse reflectance and ESR spectroscopy revealed that the dopant ion (Fe3+ or Mn2+) is substituted for Ti4+ in the TG lattice. Fe3+ prolongs the crystallisation time of Fe,TG, whereas Mn2+ has a smaller effect on the crystallisation time in comparison with Fe3+. The as-synthesised M,TG materials were used directly as single-source precursors for the preparation of metal-doped titania (M,TiO2) through a simple thermal treatment process. The as-prepared M,TiO2 materials maintain the rod-like morphology of the precursors and possess a mesoporous structure with high crystallinity. It has been proved that the dopant ions are incorporated into the TiO2 lattice at the Ti4+ positions. The photocatalytic activities of the M,TiO2 materials obtained were evaluated by testing the degradation of phenol under UV irradiation. From the photocatalytic results, it was concluded that high crystallinity, a large surface area and appropriate transition-metal-doping are all beneficial to the enhancement of the photocatalytic performance of the doped TiO2 material. In addition, it was noted that in comparison with Mn,TiO2, Fe,TiO2 shows higher photocatalytic activity due to the better inhibition effect of Fe3+ on recombination of photogenerated electron,hole pairs. In contrast to the conventional nanosized TiO2 photocatalyst, the micrometre-sized M,TiO2 particles we obtained can be easily separated and recovered after the photocatalytic reactions. [source] Kinetic and DFT Studies on the Photoinduced Desorption of Sulfur from Gold Nanoparticles Loaded on Titanium DioxideCHEMPHYSCHEM, Issue 12 2005Tomokazu Kiyonaga Cleaning poisoned gold catalysts: Kinetic analysis of the photoinduced desorption of sulfur from gold nanoparticles loaded on TiO2 particles in water revealed that the rate constant increases with increasing pH. Photoelectrochemical measurements and DFT calculations led to the conclusion that this reaction results from an upward shift in the Fermi energy of gold nanoparticles by irradiation. The picture shows a high-resolution TEM image of an Au nanoparticle on TiO2. [source] Environmentally friendly coloured materials: cellulose/titanium dioxide/inorganic pigment composite spherical microbeads prepared by viscose phase-separation methodCOLORATION TECHNOLOGY, Issue 6 2007Shoji Nagaoka In order to develop environmentally friendly coloured materials, cellulose composite spherical microbeads hybridised with titanium dioxide (TiO2) particles and inorganic pigment were prepared by a phase-separation method using viscose and an aqueous solution containing sodium polyacrylate. Findings regarding the relationships between cellulose xanthate and the electronic characteristics of TiO2 particles used in the cellulose/inorganic material composite sphering process are also reported. These findings suggest that the location of TiO2 particles in cellulose microbeads is related to electrical repulsion between the xanthate (CSS,) group and TiO2. The use of TiO2 powder as colour pigment is limited, as its colour is white. The cellulose composite spherical microbeads covered with TiO2 and Fe2O3 particles were developed by addition of iron oxide (Fe2O3). Their surfaces were viewed by laser microscope and using SEM images. These composite microbeads retained the photocatalytic property of TiO2. Cellulose/TiO2/Fe2O3 composite spherical microbeads with both colour function and photocatalytic properties were successfully prepared. [source] | |||||||||||||