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effect of ph on hydrogen peroxide

The reaction rate of catalase on hydrogen peroxide was measured on a scale of 0-5 (0 being no reaction and 5 being fastest rate) based off the observation of bubbles during the reaction. Overview. As the H2O2 level was lowered, the influence of the pH of the solution on the rate of E. coli destruction was more notorious. Mean Values and Standard Deviation (SD) of the Parameter ΔE for Wine and Tobacco Solutions. ). The walls are lined with white standardized background (Leneta). With the completion of the reaction, all of the peroxide is converted to water. PH 7 allows the reaction to take place faster as enzyme-substrate complexes can be formed to produce a product. During the pilot study, it was observed that it takes more time for a significant lightening of the tobacco solution compared with wine, and because of this, a longer time was set for it. There were significant differences among the different pH values for the wine and tobacco solutions (p=0.0001). (i) Pour distilled water into a clean boiling tube until it is half full. The efficacy of hydrogen peroxide bleaching is directly proportional to the increase in its pH. Copyright © 2021 Elsevier B.V. or its licensors or contributors. Products that are stored in separate bottles and mixed at time of use seem to be the best option, keeping the peroxide at an acidic pH for stability and immediate alkalinization during clinical use. The hydroxyl radicals react with more peroxide and result in the formation of more perhydroxyl radicals and water (equation 3). The hypothesis was that hydrogen peroxide will be broken down by catalase into hydrogen and oxygen, where a higher concentration of inhibitor will yield less oxygen, resultant of a lower rate of reaction. Clinical application of whitening products with an alkaline pH needs further study since other variables inherent to in vivo treatment may represent changes in the bleaching efficacy. By using buffer solutions at pH 6. Figure 4 shows the mean values of ΔE for the different pH values of tobacco solution. Aim. The experiment involves measuring the quantity of oxygen produced, using the following method. On the other hand, other studies have shown similar efficacy comparing whitening gels with acid and neutral pH.6,32  These results might be due to the use of manufactured bleaching gels with different formulations, which may contain other ingredients in the formula, such as thickeners, fluoride, potassium nitrate, and others (depending on the manufacturer), which could interfere with the final result of bleaching in a more expressive way than just the pH. The entire set was covered with a dark chamber adapted to the shape of the spectrophotometer so that the reading of the solution's color was held in the dark (Figure 1). 0 % hydrogen peroxide throughout the experiment. The waiting time between the first and second readings of the spectrophotometer was determined based on previous tests, performed in order to determine a significant color variation, that is, ΔE ≥ 3.0, which is visually perceptible.24,25  The variation in the color of solutions containing the chromogen agents after bleaching can be seen in Figure 2. The null hypothesis of this study was that pH values of bleaching agents have no significant influence on the outcomes of tooth-bleaching procedures. The concentration of the enzymes. This is due to the fact that this pH does not affect the active site. With a further increase of pH and excess of alkalinity, these hydroxides are redissolved and release the metal ions, which increase the catalytic activity even more, therefore increasing the bleaching effect.39. The pure hydrogen peroxide pH must be below 4.5 to make the compound stable. Search for other works by this author on: Erica Crastechini, DDS, MS, UNESP – Univ. The pH of this mixture was measured with a pH meter (SevenMulti, Mettler Toledo, Schwerzenbach, Switzerland), equipped with an electrode (Inlab Viscous, Mettler Toledo), which was calibrated using solutions with pH 4.01 and 6.86. 8,10,32 As it concerns pH, the results reported in our study, directly measuring the color of the solution containing the chromogen, clearly show that the efficacy of hydrogen peroxide bleaching is directly proportional to the pH of the solution. Therefore the results from the investigation and the graphs show that the optimum pH is pH7. Therefore, to develop a more efficient dental bleaching gel, we have to improve the activity of the hydrogen peroxide molecule itself, boosting the chemical reaction that promotes the bleaching. One of the main polyphenol components of tobacco is rutin,29-31  whose structure is shown in Figure 5B.31  According to the measured values of ΔE, it is evident that the chromogen solution present in tobacco is more resistant to oxidation by hydrogen peroxide than the one present in wine. By continuing to use our website, you are agreeing to, http://www.oecd-ilibrary.org/environment/test-no-404-acute-dermal-irritation-corrosion_9789264070622-en. Effectiveness of H2O2 solutions against E. coli ATCC 35218 appeared to improve at both higher H2O2 concentrations and more acidic pH values. The possibility of burns is another reason for increasing attention to the total isolation from soft tissues to the teeth using a gingival barrier or a rubber dam. Adbel-Halim and Al-Deyab11  evaluated the bleaching in cotton fabrics using hydrogen peroxide and concluded that the rate of H2O2 decomposition elevates significantly with the increase of the pH from 5 to 11 and that the pH exhibits a large effect on the time required for the complete decomposition of the hydrogen peroxide and for the bleaching effect. However, with time, they can penetrate through the pores of the enamel and become intrinsic.1-3, Pigments, also called chromogens, have in common a structure shaped like a complex carbon chain, with many double bonds, which absorbs most ambient light affecting the tooth structure. Then, a final color reading was performed, and the software calculated the values of the general color variation (ΔE) using the formula ΔE = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2, according to the instructions of the Commission Internationale de l'Éclairage.23. When in contact with oral tissues, the molecule is decomposed, producing highly reactive free radicals. According to Brooker, Widmaier, Graham and Stili… Catalase is a heme containing enzyme usually found in high concentrations in cellular organelles called peroxisomes (www1). The factors that change the decomposition of hydrogen peroxide include impurities, temperature, pH, and metal ions from solutions. According to Brooks and Moore,35  hydrogen peroxide decomposes into H+ and perhydroxyl (equation 1). There were no significant differences in the bleaching effect, comparing the wine solutions with pH between 3 and 5. Factors such as the influence of high pH on the stability of other components of the formulation, the issue of potential pulp irritation caused by alkalinity, and product stability require further analysis. Effect of pH on catalase Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells (Castro, 2014). ABSTRACT. 404: Acute Dermal Irritation/Corrosion OECD Publishing; Retrieved online from: This site uses cookies. The pH of the hydrogen peroxide. (C): Cuvette with stained solution being positioned in support. After this time, the solution was filtered to remove the solid portion of tobacco and then stored in a capped bottle under refrigeration at 5°C until use. For that, we have to understand and control all variables that exert a direct effect on free radical generation and availability. By using the same quantity and focus of hydrogen peroxide, which is 2. The latter leads to the formation of free radicals (equation 2), which are the active species of oxidizing chromogens. Recipient(s) will receive an email with a link to 'Influence of pH on the Effectiveness of Hydrogen Peroxide Whitening' and will not need an account to access the content. According to the OECD Guidelines for Testing of Chemicals, related to acute dermal irritation/corrosion, substances exhibiting pH extremes such as <2.0 and >11.5 may have strong local effects, identifying those substances as corrosives to skin or mucosa.42  If the pH is >2.0 and <11.5, it is assumed as not corrosive or irritative in relation to pH. The effects of pH on the mechanism of hydrogen peroxide and lipid hydroperoxide consumption by myoglobin: a role for the protonated ferryl species. The efficacy of hydrogen peroxide bleaching is directly proportional to the increase of its pH. https://doi.org/10.1016/S0891-5849(01)00534-2. Conclusions: Despite the effectiveness of 35% hydrogen peroxide, changes on gel pH did not affect the whitening efficacy, and the enamel was superficially demineralized, regardless of pH values. 8 throughout the experiments. Catalase breaks down H 2 O 2 (hydrogen peroxide) into water and oxygen.. H 2 O 2 is a toxic substance formed during anaerobic respiration.. Catalase is an enzyme, found in the cells of animals, plants, and aerobic bacteria, which promotes the conversion of hydrogen peroxide to water and oxygen (Catalase). The results on tobacco holoperoxidase stabilization at pH 1.8 in the presence of calcium cations and drop in reaction rate constant for the enzyme interaction with hydrogen peroxide are explained by a hypothetical formation of ionic bonds between Glu-141 and the triad of aspartic acid residues via calcium cation lowering the accessibility of the active site and stabilizing the holoenzyme. Wine is produced from grapes and contains anthocyanin, which is responsible for the reddish and purple pigmentation in fruits and vegetables.26,27  The carbon chain of this chromophore is shown in Figure 5A.28  The polyphenols contained in tobacco plants play an important role in physiological processes of the plant metabolism. Effectiveness of H2O2 solutions against E. coli ATCC 35218 appeared to improve at both higher H2O2 concentrations and more acidic pH values. The constant for this process is strongly pH-dependent (k = 9.5 × 10−3s−1, pH 7: k = 2.3 × 10−1s−1, pH 5). Hydrogen peroxide 50% was mixed with red wine or with an alcoholic solution of tobacco in glass cuvettes, resulting in final peroxide concentrations of 16.97% and 21.12%, respectively. The activity of the enzyme is reduced when pH levels are increased or reduced from this optimal pH range. The pH of this mixture was measured and adjusted with 3.3 M HCl solution or 2.5 M NaOH solution to obtain the final pH values of 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0. If this contact occurs, a chemical burning is always expected by the oxidative effect of hydrogen peroxide, even in a neutral pH. Given the importance of objective parameters for the development of new formulations, the aim of this study was to determine the optimal pH to maximize the efficacy of the bleaching effect of hydrogen peroxide on chromogens. It is very important to develop and produce dental bleaching gels that are the most efficient and safe as possible, making the technique simpler for the dentist and more comfortable for the patient. Subject: Influence of pH on the Effectiveness of Hydrogen Peroxide Whitening, (Optional message may have a maximum of 1000 characters. The … Effect Of Ph Level And Hydrogen Peroxide On Catalase Essay Sample This essay has been submitted by a student The investigation was carried out to determine how different ph levels and hydrogen concentrations, affect the activity of catalase in potato during the decomposition of hydrogen peroxide to produce water and oxygen. The ANOVA test showed significant differences for color variation considering the different pH of wine (p=0.0001, F=37.61, df=6) and tobacco solutions (p=0.0001, F=281.22, df=6). The observer angle was set to 2° and ultraviolet emission at 100%. This in vitro study aimed to investigate the influence of pH as an isolate factor, but it is known that other factors as mentioned above also influence the efficacy of the bleaching solutions. The solution was allowed to rest for 24 hours in a closed container. Independent variable: pH of hydrogen peroxide. Myoglobin catalyses the breakdown of lipid hydroperoxides (e.g., HPODE) during which the absorption band of the lipid conjugated diene (234 nm) is partially bleached. The significant increase in bleaching outcomes occurs from pH 6.0, with maximum effectiveness achieved at pH 9.0, both for wine and tobacco solutions; thus, the null hypothesis was rejected. OECD Test No. The pH profile of this transition indicates ionization of two acid-base groups with close pK values of 6.7. By continuing you agree to the use of cookies. In conclusion, the evidence that was collected throughout the trials suggested that the PH 4,7,10 on which catalyst sourced from liver effect and acts on hydrogen peroxide, has a significant effect on the reaction that encountered throughout the experiment. (B): Chemical formula of rutin, tobacco chromogen. The effect of solution pH and the modification amount of Fe3O4@C/AuNPs on the performance of electrocatalytic H2O2 reduction was investigated. Among the tobacco solutions with pH values between 3 and 5, no significant variation was observed in the bleaching effect. Arylsulfatase and β-glucuronidase are two important enzymes in humans, which play an important role in the dynamic equilibrium of steroidal estrogens. The mean ΔE values for the wine solutions are shown in Figure 3. These positive results obtained with the increase in pH values can be explained based on the chemical reactions involved in the process. To evaluate the effect of hydrogen peroxide bleaching on the wine chromogens, 1.27 mL of wine, 1.27 mL of hydrogen peroxide to 50% (Cosmochemistry, Barueri, São Paulo, Brazil), and 1.20 mL of ultra-pure water (type 1) were mixed in a glass cuvette with an optical path of 10 mm and a total capacity of 4.0 mL (G4, Biocell Buckets, Taboao da Serra, São Paulo, Brazil), resulting in 16.97% final peroxide concentration. Several studies have shown that bleaching in acidic pH can produce changes in chemical composition and surface morphology, calcium loss, and reduction in hardness and fracture resistance.13-17  On the other hand, studies of dental bleaching agents with alkaline pH have shown an increased bleaching efficacy,18  reducing its deleterious effects on enamel surface properties.19  However, there is a lack of literature in relation to the influence of pH on bleaching of chromogens commonly found in the oral cavity that are responsible for tooth darkening, such as wine and tobacco. The significant increase in bleaching outcomes occurs from pH 6.0, with maximum effectiveness achieved with pH 9.0. The molar absorptivity of the H2O2-induced difference spectrum is virtually pH-independent in the Soret band and at 570 nm, whereas the peak at 607 nm increases approx. However, for the in-office technique, highly concentrated hydrogen peroxide gels, up to 38%, are applied over the enamel but with some kind of previous gingival isolation, preventing the gel from contacting the soft tissues. (D): Cuvette in position and in contact with the spectrophotometer's frame reading. Color changes (Delta E) were calculated. The catalase and hydrogen peroxide bond form water and oxygen successfully. Procedure: 1 g of the freshly prepared or combined potato is moved into a boiling pipe. The inactivation kinetics of Escherichia coli ATCC 35218 in hydrogen peroxide solutions at different concentrations (0–3.00% w/v) and pH values (3.0–7.2) at 25C was studied. However, different H2O2 solutions may have different pH levels depending on the content of the hydrogen peroxide and the presence of any additional components (e.g. These substances are deposited on the enamel's surface and can be removed by a simple prophylaxis. Moreover, highly electrocatalytic activity to the reduction of hydrogen peroxide (H 2 O 2 ) was also exhibited on the Fe 3 O 4 @C/AuNP-modified indium tin oxide (ITO) electrode. Changes in tooth color may be of intrinsic or extrinsic causes. Therefore, the aim of the present study was to investigate the effects of 30% hydrogen peroxide solutions with different pH values on enamel surface morphology, chemical composition, and color. To determine the effects of pH on catalase enzyme activity. Alkaline conditions stabilize the ferryl species, making myoglobin considerably less reactive towards lipids and lipid hydroperoxides. They showed that the decomposition was faster and more violent when the peroxide was mixed with 20% sodium hydroxide than when mixed with hydrochloric acid and ether. Thus, during the bleaching treatment, the direct contact between gel and soft tissues must be avoided. MetMb (10 μM) was mixed with H 2 O 2 (10 μM) and the absorbance changes monitored for 4.5 h. Fig. The perhydroxyl anion is the primary key species responsible for the bleaching outcomes. Y. Pong In connection with our studies on the darkening of fruit tissue, investi-gations have been made on the effect of hydrogen ion concentration and hy-drogen peroxide concentration on the behavior of the oxidase system of the apricot. Ten samples were prepared for each solution at each pH. The reading frame of the spectrophotometer was adjusted to contact the front part of the cuvette. Hydrogen peroxide solutions with a higher pH are used to increase the efficacy of the process.12  In relation to dental bleaching gels, a large number of products present an acidic pH in order to increase the product's shelf life, since hydrogen peroxide is more stable in an acidic environment. The purpose of this experiment was to determine the optimal substrate concentrations and ph levels under which enzymatic reactions involving the enzyme catalase will occur successfully. ), *Carlos R G Torres, DDS, PhD, UNESP – Univ. In relation to the efficacy of the bleaching procedure, the oxidative activity of the hydrogen peroxide molecule is strongly dependent on several factors. Therefore, determining a pH that is safe and allows for bleaching of chromogenic substances available in the oral environment with maximum efficacy is very important for the development of new formulations and products. Estadual Paulista, Institute of Science and Technology, Department of Restorative Dentistry, São Paulo, Brazil, Fernanda Alves Feitosa, DDS, MS, UNESP – Univ. Peroxidase activity ceases at a pH of 2.5 or 8.5 to 9.5. Introduction. The H+ release explains their behavior as a weak acid. Estadual Paulista, Institute of Science and Technology, Department of Restorative Dentistry, São Paulo, Brazil, Alessandra Bühler Borges, DDS, MS, PhD, UNESP – Univ. The color change and pH of the in-office bleaching product during application was also evaluated. Thus, an in vitro method for testing the action of peroxide on chromogens without the use of tooth substrate is simple, and a larger number of combinations can be assessed, avoiding the complexities resulting from chemical diffusion and optical transmission within the tooth.18  When we use tooth structure, other variables are present, such as tooth age, mineralization status, initial color, diameter and number of dentin tubules, and differences in the numbers of organic and inorganic compounds. I think that when we test the surface area the bigger the surface area the quicker the reaction will be. Effect of changing substrate concentration on the amount of oxygen gas produced in the reaction between catalase and hydrogen peroxide. The activity of the peroxidase enzyme is dependent on pH. Mean ΔE values in relation to the increase in the pH of wine. The pH dependence for the auto-reduction of the ferryl species is the same as that of the myoblobin catalyzed breakdown of HPODE. The experiment tested the effects of catalase in liver on hydrogen peroxide at different temperatures and pH. Therefore, no irritative effects are expected for a bleaching compound in this range, with the possible aggressive effects related to the oxidative action of hydrogen peroxide by itself. Why we do the experiment: The body holds of thousands of different types of enzymes that regulate the chemical reactions in our body that we need to live. Objective: This in vitro study aimed to quantify the penetration of hydrogen peroxide (HP) into the pulp chamber in teeth submitted to in-office bleaching with varied pH and application techniques. Effect of pH and hydrogen peroxide produced by Lactobacillus hilgardii on Pediococcus pentosaceus growth Ana V. Rodriguez, Ana V. Rodriguez Centro de Referenda para Lactobacilos (CERELA), Chacabuco 145, 4000 San Miguel de Tucumán, … Chen and others8  investigated hydrogen peroxide decomposition using a system in which two bottles were connected and sealed. Constants: room temperature, 2 grams of potato, 15 mL of hydrogen peroxide, 10 mL of pH changing substance, and 2 minute for a reaction to occur. An initial reading of the L*a*b* chromatic coordinates was performed immediately after mixing and then after 10 minutes for wine and 20 minutes for the tobacco solution. However, this low pH can promote enamel demineralization. (A): Tobacco solution at baseline and after 20 minutes of bleaching. However, when the pH is high, there is the formation of insoluble iron hydroxide (colloidal hydroxide), which exerts higher catalytic activity for the peroxide decomposition than the complex peroxide or per-ions. It exhibits maximum activity at a pH between 6.5 and 7.0, depending on the source from which the peroxidase is derived. The L* value is a measure of lightness from 0 (perfect black) to 100 (full white), the a* axis represents red (positive a*) to green (negative a*), ranging from +120 to −120, and the b* axis represents yellow (positive b*) to blue (negative b*), also ranging from +120 to −120.23  The data were analyzed by the software Spectramagic NX (Konica Minolta Inc, Tokyo, Japan). After mixing, the color of these solutions was evaluated in a reflectance spectrophotometer; readings were repeated after 10 minutes for the wine solution and 20 minutes for the tobacco solution. THE EFFECT OF pH VALUE AND HYDKOGEN PEROXIDE CON-CENTRATION ON FRUIT OXIDASE ACTIVITY W. V. Cruess and W . ...of the enzyme catalase on hydrogen peroxide while subject to different concentrations of an inhibitor. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Obviously, the description above is simplified due to the possible formation of intermediates and other active species. The hydrogen peroxide molecule has strong oxidation activity. Table 1 presents the results of the Tukey test for the wine and tobacco solutions. Iron(II) is oxidized by hydrogen peroxide to iron(III), forming a hydroxyl radical and a hydroxide ion in the process. Different variables (independent, dependent and controlled) were put into consideration during the laboratory session to find out how much oxygen was produced. This aims to prevent the formation of oxygen and water inside the bottle, thus enhancing the validity of the product, although its whitening efficacy is suppressed.8,9,40,41  The high level of hydrogen peroxide stability and its reduced catalytic activity in acid systems were attributed to the lack of an initiator necessary to decompose hydrogen peroxide into free radicals.41  The perhydroxyl ion, which is supposed to start the decomposition of hydrogen peroxide in alkaline solutions, is present in insignificant amounts in acidic solutions since the ionization of hydrogen peroxide is not favored. Stoichiometric experiments showed that the formation of perhydroxyl ion is influenced by pH; thus, the higher the pH, the more ions are formed, leading to more free radical production. Due to the reversibility of the hydrogen peroxide reduction/oxidation processes, the initial potentials for hydrogen peroxide oxidation are the same except for pH 6.0, for which both reactions are hindered in the potential region from −0.43 V to 0.60 V. In contrast to hydrogen peroxide reduction, double wave in the polarization curves for hydrogen peroxide oxidation appears in alkaline solutions … 3-fold upon alkalinization in a narrow pH range 6.0-7.2, the effect being reversible. Catalase disproportionate: 2H2O2 → 2H2O + O2 Catabolic reactions provide raw materials and energy to start up various anabolic activities (www2). We propose that the protonated form of ferryl myoglobin (Fe4+ − OH−) is the reactive species regulating the peroxidatic activity of myoglobin. (a) Investigating the effect of pH on the rate of decomposition of hydrogen peroxide by catalase. It is known that the color observed in any structure actually corresponds to the light wavelength being reflected by it. Effect of pH on the rate constants of hydrogen peroxide catalyzed formation of ferryl myoglobin ( ) and on the rate constant of ferryl auto-reduction (•). Clinical significance: Independently of the pH value of whitening gel, enamel undergoes superficial demineralization and with a reduction in superficial microhardness that does not return to the initial … 5cm3of 3. A free radical mechanism. (A): Support for the spectrophotometer with the device positioned. There are also gels on the market in which an alkalizing agent should be mixed with hydrogen peroxide during clinical use, so that it is used with a higher pH,30  thereby improving the bleaching efficacy and preventing dental surface demineralization.18  The effects of alkaline pH in soft tissues range from mild irritation to severe ulcers. The data were analyzed using statistical parametric tests of one-way analysis of variance (ANOVA) and Tukey, with a significance level of 5%. Mean ΔE values in relation to the increase in the pH of the tobacco. stabilizers, etc. The final concentration of hydrogen peroxide solution into the wine mixture was 20% (w/v) and of the tobacco mixture was 25% (w/v). pH. doi: https://doi.org/10.2341/13-214-L. To evaluate the influence of pH on the bleaching effect of hydrogen peroxide on chromogen agents. Copyright © 2001 Elsevier Science Inc. All rights reserved. The two variables I am going to look at are temperature and surface area. Without the enzymes working at A custom-made device for adjustment in the spectrophotometer was used at the time of color reading, so that three sides of the cuvette were covered with a standard white background, which had the chromaticity coordinates L* = 93.10, a* = −1.27, and b* = 4.95 (Leneta, The Leneta Co, Mahwah, NJ, USA), as shown in Figure 1. The authors found an increase in the speed of the reaction between pH 8 and 9.18  In studies with human teeth, an increase in the whitening efficacy of bleaching gels with alkaline pH was also observed, when compared with acid gels.19,33  In addition, alterations in enamel surface properties were investigated, and there was no evidence of erosion when gels with neutral or alkaline pH were used,19  different from what occurred in studies on dental tissues in acidic environments.8,34. The perhydroxyl anion interacts with another peroxide molecule and results in the formation of the free radicals hydroxyl (HO)• and perhydroxyl (HO2)•, also called active species (equation 2). Enzymes are essential for life because they serve various functions in the body such as helping with digestion and metabolism. The radicals are formed slowly, without the presence of a catalyst in a reaction called self oxidation-reduction.9  In the presence of metal ions or enzymes, that reaction can be accelerated.10  The same is observed with increasing temperature.11. These findings are significant for understanding myoglobin-induced oxidative stress in vivo and the development of therapies. The at-home bleaching technique uses hydrogen peroxide gel in low concentrations, up to 10%, in trays or strips applied over the patient's teeth with no special isolation, without major irritative effects on the soft tissues. From pH 6 onward, the alkalinity significantly increased the bleaching effect of hydrogen peroxide on the colored solution.

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