Influence Of TiO2 Nanoparticles Research Articles

Influence of TiO2 Nanoparticles on the Physical, Mechanical, and Structural Characteristics of Cementitious Composites with Recycled Aggregates.

The aim of this study is to analyze the effect of the addition of TiO2 nanoparticles (NTs) on the physical and mechanical properties, as well as the microstructural changes, of cementitious composites containing partially substituted natural aggregates (NAs) with aggregates derived from the following four recycled materials: glass (RGA), brick (RGB), blast-furnace slag (GBA), and recycled textolite waste with WEEE (waste from electrical and electronic equipment) as the primary source (RTA), in line with sustainable construction practices. The research methodology included the following phases: selection and characterization of raw materials, formulation design, experimental preparation and testing of specimens using standardized methods specific to cementitious composite mortars (including determination of apparent density in the hardened state, mechanical strength in compression, flexure, and abrasion, and water absorption by capillarity), and structural analysis using specialized techniques (scanning electron microscopy (SEM) images and energy dispersive X-ray spectroscopy (EDS)). The analysis and interpretation of the results focused primarily on identifying the effects of NT addition on the composites. Results show a decrease in density resulting from replacing NAs with recycled aggregates, particularly in the case of RGB and RTA. Conversely, the introduction of TiO2 nanoparticles resulted in a slight increase in density, ranging from 0.2% for RTA to 7.4% for samples containing NAs. Additionally, the introduction of TiO2 contributes to improved compressive strength, especially in samples containing RTA, while flexural strength benefits from a 3-4% TiO2 addition in all composites. The compressive strength ranged from 35.19 to 70.13 N/mm2, while the flexural strength ranged from 8.4 to 10.47 N/mm2. The abrasion loss varied between 2.4% and 5.71%, and the water absorption coefficient varied between 0.03 and 0.37 kg/m2m0.5, the variations being influenced by both the nature of the aggregates and the amount of NTs added. Scanning electron microscopy (SEM) images and energy dispersive X-ray spectroscopy (EDS) analysis showed that TiO2 nanoparticles are uniformly distributed in the cementitious composites, mainly forming CSH gel. TiO2 nanoparticles act as nucleating agents during early hydration, as confirmed by EDS spectra after curing.

The Influence of TiO2 Nanoparticles on the Physico–Mechanical and Structural Characteristics of Cementitious Materials

The urgent need for sustainable construction that corresponds to the three pillars of sustainable development is obvious and continuously requires innovative solutions. Cementitious composites with TiO2 nanoparticles (NT) addition show potential due to their improved durability, physico–mechanical characteristics, and self-cleaning capacity. This study aimed to evaluate the influence of NT on cementitious composites by comparing those with 2%–5% nanoparticles with a similar control sample without nanoparticles, as well as an analysis of cost growth. The experimental results showed an increase in bulk density of the material (4.7%–7.4%), reduction in large pore sizes by min. 12.5%, together with an increase in cumulative volume and cumulative specific surface area of small pore sizes, indicating densification of the material, also supported by SEM, EDS, and XRD analyses indicating acceleration of cement hydration processes with formation of specific products. The changes at microstructural level support the experimental results obtained at macrostructural level, i.e., modest but existent increases in flexural strength (0.6%–7.9%) and compressive strength (0.2%–2.6%) or more significant improvements in abrasion resistance (8.2%–58%) and reduction in water absorption coefficient (37.5%–81.3%). Following the cost–benefit analysis, it was concluded that, for the example case considered of a pedestrian pavement with a surface area of 100 m2, using 100 mm thick slabs, if these slabs were to be made with two layers, the lower layer made of cementitious composite as a reference and the upper layer with a thickness of 10 mm made of cementitious composite with 3% NT or 4% NT, the increase in cost would be acceptable, representing less than 15% compared to the cost for the exclusive use of cementitious composite without NT.

Titanium Dioxide Promotes the Growth and Aggregation of Calcium Phosphate and Monosodium Urate Mixed Crystals.

The increased utilization of titanium dioxide (TiO2) nanoparticles (TNPs) in various industrial and consumer products has raised concerns regarding its harmful effect due to its accumulation within the different systems of the human body. Here, we focused on the influence of TNPs on the growth and aggregation of two crucial crystalline substances, calcium phosphate (CaP) and monosodium urate (MSU), particularly its implications in gout disease. In this study, we adopted microscopic techniques and generated kinetic models to examine the interactions between TNPs, CaP and MSU, and crystallization, under controlled laboratory conditions. Our findings reveal that TNPs not only facilitate the growth of these crystals but also promote their co-aggregations. Crystal dissolution kinetics also exhibit that an increase in TNPs concentration corresponds to a reduction in the dissolution rate of CaP and MSU crystals in presence of the dissoluting agent hydroxycitrate (Hcit). These observations suggest that TNPs can stabilize CaP+MSU mixed crystals, which underscores the significance of TNPs' exposure in the pathogenesis of gout disease.

Incorporation of TiO2 nanoparticles in CoWP coating for improved wear and corrosion resistance via electrodeposition

The CoWP/TiO2 composite coating is prepared by electrodeposition by adding TiO2 nanoparticles in the plating solution. The influence of TiO2 nanoparticles on the composition, thickness, roughness, surface morphology, mechanical performance and corrosion resistance of CoWP/TiO2 composite coating is investigated. It is found that adding proper amount of TiO2 nanoparticles in the plating solution can improve the deposition rate, increase the coating thickness, and enhance the wear resistance and corrosion resistance of composite coating. TiO2 nanoparticles in the plating solution can enter the crystal lattice of CoWP alloy and induce heterogeneous nucleation during electrodeposition, which plays the role of refining grain, so as to obtain compact surface morphology with smaller surface roughness. The CoWP/TiO2 composite coating electrodeposited from the plating solution with 15 g/L TiO2 nanoparticles has the best wear resistance and corrosion resistance with the smallest wear scar depth (17.04 µm) and minimum corrosion current density (12.92 μA/cm2). When the TiO2 nanoparticles in the solution are up to 20 g/L, the agglomeration phenomenon of TiO2 nanoparticles inhibits the electrodeposition, resulting in the decline of deposition rate, the increase of alloy surface roughness, and the decrease of wear and corrosion resistance performance.

Experiments on the Electrical Conductivity of PEG 400 Nanocolloids Enhanced with Two Oxide Nanoparticles.

This paper aims to provide some insights into the pH and electrical conductivity of two classes of nanocolloids with PEG 400 as the base fluid. Thus, nanoparticles of two oxides-MgO and TiO2-were added to the base fluid in 5 mass concentrations in the range 0.25-2.5 %wt. The stability was evaluated in terms of pH at ambient temperature, while the electrical conductivity was discussed at both ambient temperature and up to 333.15 K. The electrical conductivity of PEG 400 was previously discussed by this group, while the behavior of the new nanocolloids was debated in terms of the state of the art. More precisely, the influence of MgO increases electrical conductivity, and an enhancement of up to 48% for 0.25% MgO was found, while the influence of TiO2 nanoparticles was found to be in similar ranges. In conclusion, electrical conductivity varies with temperature and the addition of nanoparticles to the base fluid, although the mechanisms that are driving the nanoparticle type and concentration influence are not yet entirely assumed in the available literature.

TiO2 Blended Membranes Used in Wastewater Nanofiltration Systems from Medical Sector

The study aims to investigate the influence of TiO2 nanoparticles on the permeation and retention properties of polymeric membranes used in wastewater nanofiltration systems from the medical sector. The research is focused on the influence of the TiO2 nanoparticles concentration on the membrane properties. Additives in general determine enhanced membrane properties like permeation and retention capacity. Hydrophobicityhowever, is decreasing due to the nanoparticles affinity for water and this have an important effect on the permeation properties, at the same time with the decrease in surface roughness, with an important influence on the fouling effect. Membranes with four different concentrations of TiO2 nanoparticles were studied, from 0 to 2% nanoparticles. Results showed that small percent of nanoparticles have an important impact on the permeation properties of the membranes, finding that at 2% nanoparticles the permeation decreases due to the nanoparticles aggregations which are blocking the pores.

Physical and Chemical Processes of Structure Formation of (BeO+TiO2)-Ceramics with the Addition of TiO2 Nanoparticles

This paper describes in detail the solid-phase sintering mechanism of BeO ++ ceramics in the 1520–1550 °C temperature range. It is shown that the structural elements are formed due to the processes of pore disappearance and grain growth in the process of ceramic shrinkage during sintering. It is found that under the influence of TiO2 nanoparticles it is possible to increase the sintering temperature of such ceramics by 30 °C, which promotes the transformation of the crystal structure of TiO2 into a more conductive Ti3O5 with an orthorhombic structure. The mechanism of the slowing down of the grain boundary movement by the second phase impurity as the segregation of nano impurities on the grain boundary is described. The calculation of binding energy of spontaneous chemical reactions during sintering of ceramics is performed, chemical elements and compounds related to conductive phase in ceramics of BeO ++ composition atsintering temperature 1550 °С are determined. It is shown that the specific conductivity of the synthesized nanocomposite material increases in comparison with the ceramics consisting of micropowders in the frequency range of 100 Hz–100 MHz, at a sintering temperature of 1550 °С.

Enhanced production of bacterial hydrolytic endoglucanase enzyme using waste leaves of water hyacinth and its thermal stability under the influence of TiO2 nanoparticles

Enhanced production of bacterial hydrolytic endoglucanase enzyme using waste leaves of water hyacinth and its thermal stability under the influence of TiO2 nanoparticles

Immobilization and redistribution process of As(V) during As(V)-bearing ferrihydrite reduction by Geobacter sulfurreducens under the influence of TiO2 nanoparticles

The redistribution process of arsenate (As(V)) and the variation in As(V) content in different locations must be clarified to ensure low mobility of As(V) during microbial ferrihydrite reduction. In this study, we investigated As(V) immobilization and redistribution processes when ferrihydrite was incubated with Geobacter sulfurreducens in the presence of titanium dioxide (TiO2) nanoparticles. Our study results showed that, As(V) in the aqueous phase and ferrihydrite were redistributed on light minerals (goethite), heavy minerals (ferrihydrite and magnetite), and extracellular polymeric substances (EPS) induced by G. sulfurreducens during ferrihydrite reduction. Interestingly, we found that As(V) in the form of arsenate ion (AsO43-) was adsorbed by the functional groups of the EPS, while the formed FeII3(AsVO4)2 was wrapped in the network structure of EPS. Moreover, the addition of TiO2 nanoparticles did not promote but delayed the entire ferrihydrite reduction, As(V) immobilization and redistribution processes. Furthermore, changes in the aqueous arsenic and iron concentrations are closely related to the formation time of secondary minerals. Our study findings provide new insights into the As(V) immobilization process mediated by G. sulfurreducens under anaerobic conditions.

Influence of TiO2 Nanoparticles on the Resistance of Cementitious Composite Materials to the Action of Fungal Species.

The development of mold films on the cement surfaces of buildings is a health and safety problem for the population, aesthetic but also in terms of their durability. The use of specific performance of cementitious composites containing TiO2 nanoparticles, photoactivated by UV radiation, can be a viable solution to mitigate to eliminate these problems. The experimental studies presented aim to analyze the capacity to inhibit the development of mold type Aspergillus and Penicillium on the surface of composite materials with nano-TiO2 content and the identification of the optimal range of nanomaterial addition. The identification and analysis of the inhibition halo (zone with a biological load of maximum 1–10 colonies of microorganisms) confirmed the biocidal capacity of the cementitious composites, but also indicated the possibility that an excess of TiO2 nanoparticles in the mixture could induce a development of cell resistance, which would be unfavorable both in terms of behavior and in terms of cost.

Non‐isothermal crystallization kinetics of polypropylene/bamboo fiber/nano‐TiO2composites

AbstractNon‐isothermal crystallization kinetics of polypropylene/bamboo fiber/nano‐TiO2(PP/BF/nano‐TiO2) composites was investigated using differential scanning calorimetric technique with various cooling rates (2.5, 5, 10, 20, and 30°C min−1). The influence of different loading concentration (0, 0.1, 0.4, and 0.8 wt%) of TiO2nanoparticles on the nucleation ability of polypropylene was evaluated. The Avrami equation, Ozawa, and Mo model were applied to describe the non‐isothermal crystallization behaviors and to analyze the experimental data of the PP/BF/nano‐TiO2composites. The Friedman isoconversional model was employed to calculate the effective activation energy (Ea) of the samples. The experimental data were in perfect agreement with the Mo model during the investigated crystallization temperature and the loading concentration of TiO2nanoparticles. The TiO2nanoparticles concentration of 0.4 wt% was useful for improving crystallization process of the PP matrix in the composites by accelerating the crystallization rate along with the lower values of t1/2and Ea. However, we observed no significant changes in the onset crystallization temperature(To) and the crystallization peak temperature(Tp) with the incorporation of TiO2nanoparticles in the PP matrix, suggesting that the influence of TiO2nanoparticles was more remarkable at the crystal growth instead of nucleation stage for the PP/BF/nano‐TiO2composites system.

Influence of TiO2 Nanoparticles on the Resistance of Cementitious Composite Materials to the Action of Bacteria.

The formation of biofilms on cementitious building surfaces can cause visible discoloration and premature deterioration, and it can also represent a potential health threat to building occupants. The use of embedded biofilm-resistant photoactivated TiO2 nanoparticles at low concentrations in the cementitious composite matrix is an effective method to increase material durability and reduce maintenance costs. Zone of inhibition studies of TiO2-infused cementitious samples showed efficacy toward both Gram-negative and Gram-positive bacteria.

IR thermographic camera as useful and smart tool to analyse defects in organic solar cells

The main goal of this paper was to show that organic layers prepared for organic solar cells construction can be partially characterized by IR thermographic camera to detect dysfunctionalities of the active layer. Moreover, we used IR thermographic camera to check thermal and electrical behaviour of created simple solar cells to reduce time and cost in global production of solar cells. As model system organic compounds such as PTB7 polymer and small molecule PC71BM as commercial components and newly synthesized imine PV-BLJ-SC11 there were used, to construct simple devices. Full Text: PDF ReferencesK. D. G. I. Jayawardena, L. J. Rozanski, C. A. Mills, M. J. Beliatis, N. A. Nismy, S. R. P. Silva, "Inorganics-in-Organics’: recent developments and outlook for 4G polymer solar cells", Nanoscale, 2013, 5, 8411-8427. CrossRef Y. Lin, X. Zhan, "Oligomer Molecules for Efficient Organic Photovoltaics", Accounts of Chemical Research, 2016, 49, 175-183. CrossRef R. Steim, S. A. Choulis, P. Schilinsky, U. Lemmer, C. J. Brabec, "Formation and impact of hot spots on the performance of organic photovoltaic cells", Applied Physics Letters, 2009, 94, 043304. CrossRef J. Hepp, F. Machui, H. J. Egelhaaf, C. J. Brabec, A. Vetter, "Automatized analysis of IR‐images of photovoltaic modules and its use for quality control of solar cells", Energy Science and Engineering. 2016, 4, 363-371. CrossRef H. Hoppe, J. Bachmann, B. Muhsin, K. H. Drüe, I. Riedel, G. Gobsch, C. Buerhop-Lutz, C. J. Brabec, V. Dyakonov, "Quality control of polymer solar modules by lock-in thermography", Journal of Applied Physics, 2010, 107, 014505. CrossRef J. Bachmann, C. Buerhop-Lutz, C. Deibel, I. Riedel, H. Hoppe, C. J. Brabec, V. Dyakonov, "Organic solar cells characterized by dark lock-in thermography", Solar Energy Materials and Solar Cells, 2010, 94, 642-647. CrossRef A. Różycka, K. A. Bogdanowicz, N. Górska, J. Rysz, M. Marzec, A. Iwan, R. Pich, A. Januszko, "Influence of TiO2 Nanoparticles on Liquid Crystalline, Structural and Electrochemical Properties of (8Z)-N-(4-((Z)-(4-pentylphenylimino)methyl)benzylidene)-4-pentylbenzenamine", Materials, 2019, 12, 1097. CrossRef M. L. Petrus, R. K. M. Bouwer, U. Lafont, S. Athanasopoulos, N. C. Greenham, T. J. Dingemans, "Small-molecule azomethines: organic photovoltaics via Schiff base condensation chemistry", Journal of Materials Chemistry A, 2014, 2, 9474-9477. CrossRef K. A. Bogdanowicz, A. Iwan, "Symmetrical Imines with Trirphenylamine Core and the Method of Obtaining Thereof.", March 11th 2019, patent application P.429044. DirectLink K. P. Korona, T. Korona, D. Rutkowska-Zbik, S. Grankowska-Ciechanowicz, A. Iwan, M. Kamińska, "Polyazomethine as a component of solar cells-theoretical and optical study", Journal of Physics and Chemistry of Solids, 2015, 86, 186-193. CrossRef

Influence of TiO2 nanoparticles (wt%) onto the physical and mechanical properties of the TiO2-geopolymer paste

The TiO2-geopolymer paste had been prepared by dry-mixing of the fly ash with various concentration (wt%) of TiO2 nanoparticles (2.5%, 5.0%, 10.0% and 15.0%). Those powder mixtures were then mixed with the alkali activator with the ratio of 2.5 and were cured at room temperature for 28 and 640 days. The phase and chemical bonding analysis revealed that the incorporation of TiO2 nanoparticles did not create any additional phase or functional group, but only physical interaction might have occurred in between the TiO2 and geopolymer matrix. However, the physical properties were depending on the TiO2 nanoparticles content where setting time of the geopolymer can be shortened by the addition of certain amount of TiO2 nanoparticles (up to 5.0 wt%). The water absorption also increased as a function of TiO2 content, due to the formation of the micro cracks as a result from the agglomeration of TiO2 nanoparticles. The compressive strength reaches its maximum value, 85.9 MPa with 5.0 wt% of TiO2 nanoparticles. Beyond 5wt%, the strength decreased almost half of the maximum value, where agglomeration becomes a main factor. While for 640 days of ageing, sample with 15.0 wt% shows triple increment from 30.6 MPa to 95.3 MPa.

Calcium phosphate formation on TiO2 nanomaterials of different dimensionality

Calcium phosphates (CaPs) composites with different TiO2 nanomaterials (TiNMs) have recently attracted attention due to their potential application as implant materials for hard tissue regeneration. Among different synthetic routes for such composites, biomimetic synthesis attracts special attention as a green synthesis route. To rationalize biomimetic synthesis, the influence of surface structure and surface charge density of different TiNMs on CaPs precipitation should be determined. In this paper, for the first time, the influence of TiO2 nanoparticles (TiNPs) and titanate nanotubes (TiNTs) on CaPs spontaneous precipitation was investigated. In addition, the ability of TiNMs to induce CaPs formation in corrected simulated body fluid (c-SBF) was tested. The advancement of the CaPs precipitation was followed by potentiometric measurements, while the obtained materials were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS), powder X-ray diffraction (PXRD), scanning (SEM) and transmission (TEM) electron microscopy, electron paramagnetic resonance spectroscopy (EPR), Brunauer-Emmett-Teller surface area analysis (BET), dynamic (DLS) and electrophoretic light scattering (ELS), atomic force microscopy (AFM) and thermogravimetric (TGA) analysis. Both TiNMs showed poor ability to promote CaPs formation in c-SBF which can be attributed to their low absolute zeta-potential value. However, during spontaneous precipitation, they exhibited uncommon dual influence on precipitation kinetics, i.e. inhibition of initially formed amorphous calcium phosphate (ACP) transformation at lower and promotion at higher concentrations. After one hour of reaction time, in the presence of both TiNMs, calcium deficient hydroxyapatite was formed (CaDHA). Morphology of the CaDHA depended on the type and concentration of TiNMs. However, PXRD, EPR and TGA characterization confirmed that there is no significant difference between CaDHA formed in the presence of different TiNMs, which indicates that CaDHA composites with different TiNMs could be prepared at similar conditions. In addition, they can be prepared in a much shorter time compared to the usual procedure with SBF. Obtained results confirm the importance of surface structure and charge in CaPs – TiNMs interactions. They as well contribute to a deeper insight into precipitation processes on the nanosurfaces, which enables a rational approach not only in the biomimetic synthesis of novel biocomposites for hard tissue regeneration but also of composites for other applications.

Disordered Adsorbed Water Layers on TiO2 Nanoparticles under Subsaturated Humidity Conditions at 235 K.

The interaction of water with TiO2 is of substantial scientific and technological interest as it determines the activity of TiO2 in photocatalytic and environmental applications in nanoparticle suspensions in water, in complex appliances, or in pure form interacting with water vapor. The influence of TiO2 nanoparticles on the hydrogen bonding structure of water molecules is an important factor that controls hydration of other species, reactions, or nucleation processes. We use a combination of ambient-pressure X-ray photoelectron spectroscopy and electron yield near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the oxygen K-edge to investigate the hydrogen bonding structure of adsorbed water on titania nanoparticles in equilibrium with nearly saturated water vapor at 235 K. The results clearly show that the net NEXAFS spectrum of adsorbed water resembles that of liquid, disordered water at 235 K, a temperature at which both homogeneous and heterogeneous freezing of bulk water is anticipated.

Curing temperature: A key factor that changes the effect of TiO2 nanoparticles on mechanical properties, calcium hydroxide formation and pore structure of cement mortars

There are several studies about the effects of addition of TiO2 nanoparticles in mortar properties, but they were made at a given temperature. However, are the effects of this addition independent of curing temperature? The present research focused on the influence of TiO2 nanoparticles at three curing temperatures: 5 °C, 20 °C and 45 °C. Four different mortar mixtures were investigated: a reference mortar (without nanomaterial) and three mortars with different percentages of TiO2 (0.25%, 0.5% and 1%) by the total amount of cement for the reference mortar. For each curing temperature, the effect of TiO2 on (i) compressive and flexural strength at 7 days, (ii) calcium hydroxide (CH) formation at 1, 3 at 7 days and (iii) pore structure have been studied. The effect of TiO2 on compressive and flexural strength depends strongly on curing temperature: the higher the curing temperature, the lower the positive effect of TiO2. If this fact is not considered when curing temperature is higher than the standard (20 °C), improvements due to TiO2 substitution would not be as considerable as it is expected. TiO2 promotes CH carbonation during sample preparation. Results suggest that promotion of hydration is not the only effect of TiO2, which can contribute to enhance strength. A potential mechanism of these nanoparticles to enhance strength could be the modification of pore structure; according to 3D X-Ray microscope results, at 20 °C, TiO2 makes pores smaller, more homogeneous and spherical.

Thermohydraulics of TiO2/Water Nanofluid in a Round Tube with Twisted Tape Inserts

The influence of TiO2 nanoparticles with different volume concentrations in water on heat transfer, friction and thermal performance is explored, and finite volume method is used to clarify the heat transfer in a tube inserted with twisted tape (TT). In the experiment, swirling tubes are generated by TT insert with the twisted ratio (y/w) of 3.0 in the range of Reynolds number between 5400 and 15,200. The mathematical modeling which involves the prediction of flow behaviors in a tube is also conducted. The concentration of nanofluid (ϕ) was varied from 0.07 % to 0.21 % by volume. The results revealed that TiO2 nanoparticles suspended in water enhanced thermal conductivity, and movement of TiO2 nanoparticles delivered energy exchange. Although an increase of TiO2 concentration led to an increase in friction due to small particles suspending in fluid, the heat transfer and thermal performance could enhance significantly. As compared to pure water, the presence of TT with TiO2 nanoparticles at ϕ = 0.07 %, ϕ = 0.14 % and ϕ = 0.21 % indicated a 0.7 %, 1.7 % and 3.1 % higher thermal performance, respectively. With a higher Reynolds number, the thermal performance would be less pronounced due to high flow friction. From the experimental results, the understanding in relation to the effects of TiO2 concentration and Reynolds number on Nusselt number (Nu), friction factor (f) and thermal performance factor (η) is presented for a wide range of thermophysics and heat transfer application.

Toxic effect of titanium dioxide nanoparticles on morphological characteristics of thymus

Aim. Study of effects of titanium dioxide nanoparticles administered orally on the rodent thymus morphological and functional state. Methods. The study used classical morphological approaches and specific markers of proliferation - Ki-67, apoptosis - p53 protein and macrophages - CD68, which allow adequately identifying not only the cells themselves, but also their functional state. The rodent thymus was analyzed after oral administration (10 mg/kg of body weight of the animal, 28 days) of the TiO2 nanoparticles (rutile form, 40-60 nm) obtained by diluting the TiO2 powder in distilled water. Aggregation of the nanoparticles was prevented by processing a suspension of nanodispersed TiO2 in an ultrasonic bath. The rats of the control group were orally injected with distilled water in the same volume. Serial paraffin sections of the thymus were stained with hematoxylin-eosin, picrofuxin according to Van Gieson, immunohistochemical staining was performed with antibodies to Ki-67, CD68, p53. Results. Significant changes of the tissue of thymus gland under the influence of TiO2 nanoparticles were revealed. In the thymus of experimental animals, a decrease in the proportion of cortex was found to be 17.6 %, a significant decrease in the density of the cell population due to decrease in the number of thymocytes was demonstrated. Immunohistochemical typing revealed that under the influence of TiO2 nanoparticles, a decrease in the number of Ki-67-positive cells in the cortex of the lobule of the thymus gland was observed, which indicates the inhibition of proliferation in these conditions. Under the influence of TiO2 nanoparticles, an increase of the amount of cells entering apoptosis in the cortex of the thymus segment of the experimental group by 5.18 times was observed, as evidenced by the results of immunohistochemical study of the expression of apoptosis marker p53 protein. Perhaps, as a compensatory mechanism there is a pronounced increase in the number of macrophages, as indicated by an increase in the average number of CD68 immunopositive cells in the cortex of the thymus of the test group by 2.61, and in the brain substance by 1.35. Conclusion. The revealed morphological and functional changes of the thymus with oral administration of TiO2 nanoparticles indicate their immunosuppressive effect.

Influence of Food and Industrial Grade Titanium Dioxide Nanoparticles on Microbial Diversity and Phenotypic Response in Model Septic System

Abstract This investigation focused on the affect that food-grade (FG) titanium dioxide (TiO2) nanoparticles (NPs), commonly found in consumer products, can have on the instrumental biological process of degrading household waste in septic systems. Microbial communities are instrumental in the sustainability of natural and engineered environments by degrading organic matter to products easily removed by other organisms. Wastewater treatment is one such engineered environment, where large-scale facilities use activated sludge and other processes to reduce organic matter and waste reintroduced into water systems. TiO2 NPs represent a commonly detected contaminant in the wastewater influent reaching treatment facilities. However, while influence of TiO2 NPs in large-scale, multistage treatment operations has been well studied, decentralized septic systems, utilized in 25% of U.S. homes, are neglected. Unlike centralized water treatment facilities, septic system function is entirely dependent on the health of...