Effects Of nano-TiO Research Articles

Effects of Nano-TiO 2 particles on bioaccumulation of 133 Cs from the contaminated soil by Soybean ( Glycine max )

This study investigated the effects of nano-TiO2 particles on cesium uptake by soybean plant, which was conducted in a plant growth chamber with adding different concentrations of 133Cs to the soil. This study identified compositional and functional group changes of the elements contained in the soybean root and shoot due to the accumulation of 133Cs. With use of nano-TiO2, the accumulation of 133Cs identified in the shoot (731.7 μg/g dw) was higher than that in the root (597.8 μg/g dw). The Cs 3d peaks identified in the XPS spectrum analysis of the shoot and root biomass could be an evident for 133Cs accumulation. The appearance of the new FTIR peaks on the root and shoot biomass can be explained by new bond formation of 133Cs or nano-TiO2 with biomass matrix. Therefore, the application of nano-TiO2 in Cs contaminated soil can significantly enhance 133Cs uptake and its accumulation in plants.

Nanocomposites of NR/SBR Blend Prepared by Latex Casting Method: Effects of Nano-TiO2 and Polystyrene-Encapsulated Nano-TiO2 on the Cure Characteristics, Physical Properties, and Morphology

Nanocomposites of 80/20 (w/w) natural rubber (NR)/styrene butadiene rubber (SBR) blend with four loadings of either nanosized titanium dioxide (nTiO2) or polystyrene-encapsulated nTiO2 (PS-nTiO2), ranging from 3 to 9 parts by weight per hundred of rubber (phr), were prepared by latex casting method. The PS-nTiO2 synthesized via in situ differential microemulsion polymerization displayed a core-shell morphology (nTiO2 core and PS shell) with an average diameter of 42 nm. The cure characteristics (scorch time, cure time, and cure rate index), mechanical properties (tensile properties, tear strength, and hardness), thermal stability, glass transition temperature, and morphology of the prepared nanocomposites were quantified and compared. The results showed that the cure characteristics of all the nanocomposites were not significantly changed compared to those of the neat NR/SBR blend. The inclusion of an appropriate amount of either nTiO2 or PS-nTiO2 into the NR/SBR blend apparently improved the tensile strength, modulus at 300% strain, tear strength, hardness, and thermal stability but deteriorated the elongation at break of the nanocomposites. Based on differential scanning calorimetry, the glass transition temperature of all the nanocomposites was similar to that of the neat NR/SBR blend. Moreover, the morphology of the PS-nTiO2-filled rubber nanocomposites fractured surface analyzed by scanning electron microscopy showed an improvement in the interfacial adhesion between the rubber phase and the nanoparticles.

Effects of Nano-TiO2on the Toughness and Durability of Cement-Based Material

The effects of nano-TiO2(NT) on microstructures and mechanical properties of cement mortars were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). Results show that 3% NT can remarkably increase the tensile/flexural strengths (i.e., the toughness is improved) and promote the precipitation of AFt crystal. The flexural and tensile strengths have significant positive correlation to the formation amount of AFt. The pores of mortars can be significantly refined and shift to harmless pores by controlling the growth of CH crystal and increasing the hydration reaction rate. The durability of cement-based materials is discussed by testing their water absorption and water-vapour permeability. Results show that the addition of 3% NT can decrease the water absorption ratio by 40–65%, water absorption coefficients by more than 40%, and water-vapour permeability coefficients by 43.9%, indicating that 3% NT can effectively improve the compactness and durability of cement-based materials.

Toxicity assessment of TiO2 nanoparticles in zebrafish embryos under different exposure conditions

The popularity of TiO2 nanoparticles (nano-TiO2) lies in their wide range of nanotechnological applications, together with low toxicity. Meanwhile, recent studies have shown that the photocatalytic properties of this material can result in alterations in their behavior in the environment, causing effects that have not yet been fully elucidated. The objective of this study was to evaluate the toxicity of two formulations of nano-TiO2 under different illumination conditions, using an experimental model coherent with the principle of the three Rs of alternative animal experimentation (reduction, refinement, and replacement). Embryos of the fish Danio rerio were exposed for 96h to different concentrations of nano-TiO2 in the form of anatase (TA) or an anatase/rutile mixture (TM), under either visible light or a combination of visible and ultraviolet light (UV). The acute toxicity and sublethal parameters evaluated included survival rates, malformation, hatching, equilibrium, and overall length of the larvae, together with biochemical biomarkers (specific activities of catalase (CAT), glutathione S-transferase (GST), and acid phosphatase (AP)). Both TA and TM caused accelerated hatching of the larvae. Under UV irradiation, there was greater mortality of the larvae of the groups exposed to TM, compared to those exposed to TA. Exposure to TM under UV irradiation altered the equilibrium of the larvae. Alterations in the activities of CAT and GST were indicative of oxidative stress, although no clear dose-response relationship was observed. The effects of nano-TiO2 appeared to depend on both the type of formulation and the illumination condition. The findings contribute to elucidation of the factors involved in the toxicity of these nanoparticles, as well as to the establishment of protocols for risk assessments of nanotechnology.

Nano-TiO2 Improve the Photosynthesis of Tomato Leaves under Mild Heat Stress

Nano-TiO(2) has been reported to promote photosynthesis in some crops; however, the mechanism behind this action remains unknown. In this research, the effects of nano-TiO(2) on leaf photosynthesis under mild heat stress were investigated. Results showed that the net photosynthetic rate, conductance to H2O, and transpiration rate of tomato leaves increased after application of an appropriate concentration of nano-TiO(2). Nano-TiO(2) also significantly decreased the minimum chlorophyll fluorescence and relative electron transport in leaves. Under mild heat stress, Nano-TiO(2) increased regulated photosystem II (PS II) energy dissipation and decreased non-regulated PS II energy dissipation. These results indicate that nano-TiO(2) plays a positive role in promoting photosynthesis in tomato leaves under mild heat stress.

Effects of nano-TiO2 on properties of cement-based materials

The effect of titanium dioxide (TiO2) nanoparticles on early age and long-term properties of cement-based materials is examined experimentally through isothermal calorimetry, chemical shrinkage, setting time, compressive strength and surface microhardness, where part of the cement is replaced with TiO2. Early age hydration is accelerated by TiO2 nanoparticles which also increase degrees of hydration of Portland cement, as evidenced by isothermal calorimetry and chemical shrinkage results. With increasing amounts of TiO2, setting time is reduced, despite decreasing cement content, due to TiO2 replacement, again showing accelerated hydration. Comparing TiO2–cement composites from two different TiO2 manufacturers, results suggest that size of nanoparticles and dispersability are critical in the rate of hydration, with smaller size agglomerates, but not necessarily smaller size particles, producing a greater effect. Compressive strength increases with higher TiO2 nanoparticle replacement at lower water-to-solids ratio (w/s = 0·40) and strength is not compromised by up to 10% TiO2 replacement at higher w/s = 0·60. However, microhardness of the composite decreases with higher TiO2 amount. Broadly, these results indicate that mineral addition as cement replacement can be optimised in terms of dosage and dispersability to achieve lower cement fractions without compromising strength, but that the potential for reductions in hardness should be considered.

Effects of Nano-TiO<sub>2</sub> on Microstructure and Properties of Ceramic-Lined Composite Steel Pipes Produced by Centrifugal Self-Propagating High-Temperature Synthesis

In order to improve the density and mechanical properties of ceramic-lined composite steel pipes produced by Centrifugal Self-propagating High-temperature Synthesis. Composite steel pipes were prepared by the method of centrifugal-SHS on the basic of Al-Fe2O3 system. With the condition of adding 6% SiO2 and 4% Na2B4O7, the effect of different amount of nano-TiO2 on the density and the mechanical properties of composite steel pipes was studied. By means of SEM analysis, XRD and mechanical tests, the results show that the ceramic layer consists of main crystal phase of α-Al2O3, with small amount phases of FeAl2O4, Al2SiO5 and B2O3. The surface of ceramic layer is smooth, without obvious crack and with good density. The shearing strength of the ceramic layer and the crushing strength of the composite pipe were 13.5 MPa under 8% (in mass) nano-TiO2 and 525Mpa. The density of ceramic layer is up to 94.2% under 8% (in mass) nano-TiO2.

Effects of nano TiO2 on the light reflectivity, morphology, and rheological behavior of LLDPE‐glass bead composites

AbstractHeat‐shield composites based on linear low density polyethylene (LLDPE) filled with micro‐hollow glass beads (HGB) and TiO2 nanoparticles were prepared through melt compounding. Two kinds of LLDPE were used as the matrix of these composites with a fixed weight ratio of 60 : 40. HGB loadings were fixed at 28 wt % of LLDPE matrix while TiO2 content varied between 8 and 28 wt % of LLDPE matrix. Interestingly, the results show with addition of TiO2 to LLDPE‐HGB composites, both the light reflectivity and the flow ability of composites show great enhancement. Especially when the TiO2 loading is 14 wt % of LLDPE, UV, and infrared reflectivity of the composites are more than 90%, showing a optimal heat‐shielding performance, and the rheological responses including the storage modulus, G′ and the complex viscosities, |η*| of this composite are the lowest among all LLDPE/HGB composites. When TiO2 content is more than 14 wt %; however, ultraviolet radiation resistance is almost unchanged while that two dynamic rheological parameters increase gradually. It is proposed that the TiO2 loading of 14 wt % should be taken as the optimal value of a light reflectivity in LLDPE matrix, which is helpful in improving the processing ability by reduction in melt viscosity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effects of Nano-TiO 2 Photocatalytic Oxidization on the Cell Cycle of BGC-823 Gastric Cancer Cells

In order to explore the mechanisms of killing cancer cells via nano-TiO2 photocatalytic oxidization,gastric cancer cell line BGC-823 was cultured as research object in this study.The morphologic changes were observed by inverted phase-contrast microscope,the apoptotic rates and cell cycle of BGC-823 cells were examined by flow cytometer.The results showed that nano-TiO2 photocatalytic oxidation caused the necrosis or secondary necrosis of BGC-823 cells,and inhibited the synthesis of DNA and their proliferation process,through arresting the G2/M phase and inducing apoptosis of BGC-823 cells.Significant arrest was observed and the apoptotic rates of BGC-823 cells reached 24.34% when the coated amount of TiO2 was 9.8×10-7 g/cm2 and the irradiation time was 40 min.

Effects of nano-TiO 2 in combination with ambient UV-irradiation on a leaf shredding amphipod

Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO 2), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO 2 as well as ecotoxicological consequences due to the interactions of nTiO 2 with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO 2 at concentrations as low as 0.2 mg L −1 on the leaf shredding amphipod Gammarus fossarum both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO 2 at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO 2 and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO 2 at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.

Effects of nanosized titanium dioxide on innate immune system of fathead minnow ( Pimephales promelas Rafinesque, 1820)

Effects of nanosized (<100 nm) titanium dioxide (TiO 2) particles on fish neutrophils and immune gene expression was investigated using the fathead minnow ( Pimpehales promelas). Expanded use of TiO 2 in the cosmetic industry has increased the potential exposure risk to aquatic ecosystems and human health. Effects of nano-TiO 2 on neutrophil function of the fathead minnow was investigated using oxidative burst, neutrophil extracellular traps (NETs) release and degranulation of primary granules. The innate immune gene expression was determined with quantitative PCR (qPCR). Application of 0.1 μg mL −1 of nano-TiO 2 in vitro stimulated oxidative burst and NET release. Intraperitoneal injection of 10 μg g −1 of nano-TiO 2 caused a significant decrease in oxidative burst, NETs release and degranulation (21%; 11%; and 30%, decrease, respectively). Fish exposed to nano-TiO 2 for 48 h in vivo had significantly increased expression of interleukin 11, macrophage stimulating factor 1, and neutrophil cytosolic factor 2 (4; 2.5; and 2 fold increase, respectively). Nano-TiO 2 has potential to interfere with the evolutionary conserved innate immune system responses, as evidenced with observed changes in gene expression and neutrophil function. This finding encourages the use of fish models in the studies of nanoparticle immunotoxicity. The lowest significant response concentration studied in vitro is four times greater than the estimated environmental concentration for TiO 2 (0.025 μg mL −1) causing concern about potential impact of nano-TiO 2 on aquatic animals and ecosystems.

Oxidative stress and apoptosis induced by nanosized titanium dioxide in PC12 cells

The nanosized titanium dioxide (nano-TiO 2) is produced abundantly and used widely in the chemical, electrical/electronic and energy industries because of its special photovoltaic and photocatalytic activities. Past reports have shown that the nano-TiO 2 can enter into the human body through different routes such as inhalation, ingestion, dermal penetration and injection. The effects of nano-TiO 2 on different organs are currently being investigated and the concerns on its large scale applications such as sunscreen, etc. indeed become more interesting for us to investigate and to find the possible right answers for right doses for a safer application. In this research, the cytotoxicity of the nano-TiO 2 was investigated in PC12 cells, a cell line used as a model in vitro for the brain neurons research. While the PC12 cells were treated with different concentrations of nano-TiO 2 (1, 10, 50 and 100 μg/ml), the viability of cells was significantly decreased in the periods of 6, 12, 24 and 48 h, showing a significant dose effect and time-dependent manner. Meanwhile, the flow cytometric assay gave indication that the nano-TiO 2 induced intracellular accumulation of reactive oxygen species (ROS) and the apoptosis of PC12 cells with the increasing concentration of nano-TiO 2. Interestingly, pretreatment of N-(mercaptopropionyl)-glycine (N-MPG), known as a type of ROS scavenger formulations, could somehow inhibit PC12 apoptosis induced by the nano-TiO 2. These results might have revealed a key mechanism in PC12 apoptosis under the effect of the nano-TiO 2 solutions.

Effects of titania nanoparticles on phosphorus fractions and its release in resuspended sediments under UV irradiation

Little is known about the effects of nano-TiO 2 on the transformation and transport of phosphorus (P) in resuspended sediments. Chemical sequential extraction was used to investigate P fractions and its release in resuspended sediments under the influence of nano-TiO 2 and UV irradiation. The results showed that the contents of sediment P in all fractions decreased with increasing nano-TiO 2 concentration in UV irradiation, while increased in the dark controls. Furthermore, P release from all fractions was greater in UV irradiation than in the controls. Elevated concentrations (10–50 mg L −1) of nano-TiO 2 in UV irradiation significantly facilitated the release of P from organic and Fe oxide fractions, possibly resulting from the partial photo-degradation of organic matter and photochemical transformation of Fe oxides. Apparently, nano-TiO 2 in UV irradiation did not immobilize the loosely sorbed P and reductant soluble P release from the resuspended sediments, possible because (1) some of P released from those fractions were refurnished by the P released from OM; (2) photocatalysis of nano-TiO 2 reduced binding capacity of the resuspended sediments. Our results suggest that the photocatalysis of nano-TiO 2 may offer the potential to regulate the transformation and transport of sediment P in the aquatic environment.

Effects of Nano-TiO 2 additions on thermal analysis, microstructure and tensile properties of Sn3.5Ag0.25Cu solder

For development of a lead-free composite solder for advance electrical components, a series of Sn3.5Ag0.25Cu (SAC) solders containing TiO 2 nanopowders have been studied. The results showed that the addition of 0.25–1 wt.% TiO 2 nanopowders into the lead-free SAC solder caused its liquidus temperature to increase by about 3.5–5.9 °C. Metallographic observations of the lead-free SAC composite solders revealed a reduction in the grain size of β-Sn, Ag 3Sn phase and Ag 3Sn phase located between the spacing lamellae. In terms of mechanical behavior, the addition of larger weight fractions of TiO 2 nanopowders in lead-free SAC solder matrix led to an improvement in microhardness, 0.2%YS and UTS. However, ductility of the lead-free SAC composite solders was observed to decrease.

Application of TiO 2 nano-particles on the electrode of dye-sensitized solar cells

In this study, nano-TiO 2 thin film electrode and solar cell have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible absorption spectra, contact angle, X-ray photoelectron spectroscopy (XPS), and current–voltage characteristics analyses. X-ray diffraction patterns show that the best sintering temperature of a nano-TiO 2 film is 600 °C, at which TiO 2 anatase phase forms best and the particle size of 8–10 nm can be obtained. The SEM images of a nano-TiO 2 thin film show that the surface of the film is smooth and porous, and the thickness of the nano-TiO 2 film is 4 μm. The measurements of contact angle between nano-TiO 2 film and deionized water (DI water) reveal that the nano-TiO 2 film is super-hydrophilic when solarized under ultraviolet. The electrode of dye-sensitized solar cell is used as a free-base porphyrin with carboxyl group, 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) as the sensitizer to adsorb onto the TiO 2 thin film. From the results of ultraviolet–visible absorption spectra and XPS analyses of the electrode, the effects of nano-TiO 2 particles’ addition to the electrode of dye-sensitized solar cell can improve the absorption of visible light (400–700 nm) and increase electrons transferred from TCPP to the conduction band of TiO 2, resulting in the enhancement of efficiency for dye-sensitized solar cells.

In vivo screening to determine hazards of nanoparticles: Nanosized TiO 2

A single-species laboratory test with terrestrial invertebrates was used to identify the hazard of nanosized TiO 2. Feeding parameters, weight change, mortality, and the activities of catalase and glutathione-S-transferase were evaluated after 3 or 14 days of dietary exposure. The effects of nano-TiO 2 were dependent on exposure concentration and duration, total consumed quantity, size and pre-treatment of particles. The intensity of a response was ruled by duration of exposure and not by consumed quantity of nano-TiO 2 or exposure concentration as expected. The response to nano-TiO 2 is described as threshold-like. The exposure concentrations 10–1000 μg TiO 2/g dry food (1.35–1025 μg of total consumed quantity of TiO 2/g animal wet wt.) were identified as safe for tested species after tested exposure period. We conclude that the response to nanoparticles is different from that of soluble chemicals therefore these two types of data should be interpreted and processed differently.

Direct continuous hydrothermal synthesis of high surface area nanosized titania

Nanosized TiO 2 powder of high surface area was prepared from an aqueous solution of titanium(IV) bis(ammonium lactato) dihydroxide using a continuous hydrothermal flow synthesis (CHFS) reactor which uses superheated water at 400 °C and 24.1 MPa as a crystallizing medium. Freeze-dried nano-TiO 2 was heat-treated in air over a range of temperatures and then the resulting powders were characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), BET surface area measurement, and Raman spectroscopy. The particle size of the ‘as-prepared’ TiO 2 made using CHFS was ca. 4.8 nm (by HR-TEM), and grew with increasing heat-treatment temperature. It was found that the onset of the anatase–rutile transition of heat-treated nano-TiO 2 in air occurred at 500 °C and reached 100% rutile at 900 °C. The Raman band ( E g) at ∼150 cm −1 of anatase (nano-TiO 2) softens as the particle size increases with heat-treatment temperature (up to 600 °C). The photocatalytic activity of the TiO 2 powders for the decolourisation of methylene blue dye was assessed. The effects of nano-TiO 2 anatase-rutile phase composition, crystallinity, and crystallite size on the catalytic activity were investigated.

Photobiological Effects of Nano-TiO&lt;SUB&gt;2&lt;/SUB&gt; Semiconductors Sol

Photobiological Effects of Nano-TiO&lt;SUB&gt;2&lt;/SUB&gt; Semiconductors Sol

Characterization of protective performance of epoxy reinforced with nanometer-sized TiO 2 and SiO 2

Nano-TiO 2 particles was uniformly dispersed and prepared into concentrated nano-paste. The effects of nano-TiO 2 particles on the performance of epoxy resin on 2024-T3 aluminum alloy were investigated. The effects of nano-SiO 2 with γ-glycidoxypropyltrimethoxy silane modification or without modification on the performance of epoxy resin were also studied. It was found that the hardness of epoxy resin was improved by the incorporation of 1 wt.% nano-TiO 2 particles or nano-SiO 2. The results of electrochemical impedance spectrum (EIS) and salt spray test indicated that the addition of nano-TiO 2/SiO 2 significantly improved the corrosion resistance of epoxy resin. Fourier transform infrared spectra (FT-IR) proved that the new absorptions at 1070 and 1090 cm −1 on silane-treated nano-SiO 2 particles, which can evidence the ring structure of Si O Si. The formation of layered ring structure of nano-SiO 2 can be explained for the enhancement of the corrosion resistance and hardness of nano-SiO 2/epoxy composite.

Effect of Nano-TiO&lt;SUB&gt;2&lt;/SUB&gt; on Strength of Naturally Aged Seeds and Growth of Spinach

The effects of nano-TiO(2) (rutile) and non-nano-TiO(2) on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.25-4% nano-TiO(2) treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation, the ribulosebisphosphate carboxylase/oxygenase activity, and the photosynthetic rate. The best results were found at 2.5% nano-TiO(2). The effects of non-nano-TiO(2) are not significant. It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO(2) improves the growth of spinach seeds still needs further study.