Use Of Scavengers Research Articles

Experimental Protocols for Sustainable Ammonia Production by Photocatalytic Nitrogen Fixation: Pitfalls and Remedial Measures

AbstractThe synthesis of ammonia (NH3) by photocatalytic nitrogen (N2) fixation has gained tremendous attention from researchers worldwide. The number of reports on different materials for photocatalytic N2 fixation is increasing year by year in the quest for developing breakthrough and sustainable photocatalysts in this field. However, there are several pitfalls (nitrogenous impurities in feed gas and on the surface of the catalyst, reaction conditions, use of scavengers, NH3 quantification methods, etc.) in the path of photocatalytic N2 fixation experiments, which can lead to the reporting of bogus NH3 production rates. Therefore, the use of accurate experimental protocols for the quantification of photogenerated NH3 requires immediate attention and focus of the researchers so that reliable data can be reported in the literature. This perspective article mainly focuses on generating awareness in the photocatalytic N2 fixation research community about the recent establishments for reporting experimental results in this field. Several pitfalls that may lead to the wrong data reporting and remedial measures to avoid them are discussed in detail. Finally, a summary of the recent advancements in this field and recommendations on future directions is provided.

Removal of malachite green from water: Comparison of adsorption in a residue-derived AC versus photocatalytic oxidation with TiO2 and study of the adsorption-photocatalysis synergy

The literature rarely compiles studies devoted to the removal of pollutants in aqueous media comparing adsorption and photocatalytic degradation, and does not pay enough attention to the analysis of combined adsorption-photocatalytic oxidation processes. In the present manuscript, the removal of malachite green (MG) from aqueous solutions has been investigated in three different sustainable scenarios: i) adsorption on activated carbon (AC) derived from a residue, luffa cylindrica, ii) photocatalytic oxidation under simulated solar light using titanium dioxide (TP) and iii) combined adsorption-photocatalytic oxidation using TP-AC (70/30 wt./wt.) under simulated solar light. The study has revealed that in the three scenarios and studied conditions, the total removal of this endocrine-disrupting dye from the solution takes place in the assayed time, 2 h, in some cases just in a few minutes. MG adsorption in the AC is a very fast and efficient removal method. MG photocatalytic oxidation with TP also occurs efficiently, although the oxidized MG is not totally mineralized. MG removal using the TP-AC composite under simulated solar light occurs only slightly faster to the MG adsorption in the AC, being adsorption the dominating MG removal mechanism for TP-AC. Thus, more than 90% of the removed MG with TP-AC under simulated solar light is adsorbed in this carbon-containing composite. The obtained results highlight the interest in adsorption, being the selection of the most suitable removal method dependent on several factors (i.e., the cost of the AC regeneration, for adsorption, or the toxicity of the intermediate oxidation species, for photooxidation).Paying attention to MG photooxidation with TiO2, comparison of two working photodegradation schemes shows that the direct photodegradation of MG from solution, avoiding any initial dark equilibrium period, is more efficient from a time perspective. The use of scavengers has proved that MG photodegradation occurs via an oxidation mechanism dominated by superoxide anion radicals.

Empowering Adsorption and Photocatalytic Degradation of Ciprofloxacin on BiOI Composites: A Material-by-Design Investigation.

Binary and ternary composites of BiOI with NH2-MIL-101(Fe) and a functionalized biochar were synthesized through an in situ approach, aimed at spurring the activity of the semiconductor as a photocatalyst for the removal of ciprofloxacin (CIP) from water. Experimental outcomes showed a drastic enhancement of the adsorption and the equilibrium (which increased from 39.31 mg g-1 of bare BiOI to 76.39 mg g-1 of the best ternary composite in 2 h time), while the kinetics of the process was not significantly changed. The photocatalytic performance was also significantly enhanced, and the complete removal of 10 ppm of CIP in 3 h reaction time was recorded under simulated solar light irradiation for the best catalyst of the investigated batch. Catalytic reactions supported by different materials obeyed different reaction orders, indicating the existence of different mechanisms. The use of scavengers for superoxide anion radicals, holes, and hydroxyl radicals showed that although all these species are involved in CIP photodegradation, the latter play the most crucial role, as also confirmed by carrying out the reaction at increasing pH conditions. A clear correlation between the reduction of BiOI crystallite sizes in the composites, as compared to the bare material, and the material performance as both adsorbers and photocatalyst was identified.

Photodynamic inactivation of different Candida species and inhibition of biofilm formation induced by water-soluble porphyrins

Background: Candida spp. is the main fungal genus related to infections in humans, and its treatment has become a challenge due to the production of biofilm and its resistance/multi-resistance profile to conventional antifungals. Antimicrobial photodynamic therapy stands out as a treatment characterized by a broad spectrum of antimicrobial action, being able to induce oxidative stress in pathogens, and porphyrins are photosensitizers with high selectivity to pathogens. Thus, this work aimed to analyze the photoinactivation of different species of Candida by two cationic (4-H2TMeP+ and 3-H2TMeP+) and one anionic (4-H2TPSP‒) porphyrins. Materials and Methods: Microdilution assays were performed to determine the MIC100, with subsequent determination of MFC100. Determination of oxidative species was done through the use of scavengers, while biofilm morphological features were investigated using the atomic force microscopy. Results: Cationic porphyrins were significantly efficient in inactivating Candida albicans and non-albicans species with 100% growth inhibition and fungicidal activity (MFC100/MIC100 ≤ 4.0). The cationic porphyrins were also able to interfere in Candida spp biofilm formation. The photo-oxidative mechanism activated by 3-H2TMeP+ in Candida spp. is concurrent with the production of singlet oxygen and oxygen radical species. In the AFM analysis, 3-H2TMeP+ was able to reduce yeast adhesion to the surface. Conclusions: Cationic porphyrins can photo-inactivate different species of Candida in both planktonic and biofilm-associated forms, and reduce the adhesion of these fungi to the surface.

BiOBr/ZnWO4 heterostructures: An important key player for enhanced photocatalytic degradation of rhodamine B dye and antibiotic ciprofloxacin

We report a facile synthesis of p-BiOBr/n-ZnWO4 heterostructures by hydrothermal/precipitation method as an important key player to enhance the photocatalytic degradation of Rhodamine B (RhB) dye and ciprofloxacin antibiotic. The structural and microstructural features confirm that p-BiOBr/n-ZnWO4 heterostructures display a mixed tetragonal/monoclinic phase with the presence of several n-ZnWO4 nanocrystals on the surface of petals of flower-like p-BiOBr microcrystals. X-ray photoluminescence (XPS) analysis of BiOBr exhibits the existence of Bi, O, and Br, whereas BiOBr/ZnWO4-5%, in addition to Bi, O, and Br, consist of signature of Zn and W. UV–Visible spectra of p-BiOBr/n-ZnWO4-5% showed better absorption than p-BiOBr and n-ZnWO4, which displayed an enhanced collection of photons in the heterojunction. An intense photoluminescence emission at room temperature was observed for p-BiOBr microcrystals as compared to p-BiOBr/n-ZnWO4. We observed the best photocatalytic activity for p-BiOBr/n-ZnWO4-2.5% in the degradation of RhB dye at 99.4% in 25 min and CIP antibiotic at 58.2% in 170 min, which is assigned due to high surface area SBET (13 m2/g), pore size, providing active catalytic sites for bonding chemical and surface interaction and bonding chemical between the bromide/oxides. Finally, we have investigated the use of scavengers for isopropanol, benzoquinone, and sodium azide, which proves that the hydroxyl (•OH) and superoxide (O2′) radicals as the foremost reactive oxygen spicies (ROS) in photocatalytic degradation of RhB dye and antibiotic CIP.

Carbon framework-encapsulated copper oxide particles to activate peroxymonosulfate for the efficient degradation of tetracycline

CuO particles encapsulated by an irregular polyhedral carbon framework (CuO@C) were prepared via a one-pot polymerization method. The prepared CuO@C exhibited a highly enhanced performance in the activation of peroxymonosulfate (PMS). Our results indicated that the rate constant of tetracycline (TC) degradation was significantly increased by more than 85%, i.e., from 0.021 to 0.147 min−1, compared with the corresponding value for the bare CuO. TC elimination was completely achieved within 40 min, with the mineralization rate reaching 75.3% in 1 h. In addition, the CuO@C/PMS system exhibited an excellent performance in complex water matrixes containing various inorganic ions. Based on the use of scavengers and spin-trapping electron paramagnetic resonance technology, reactive species including OH, SO4−, and 1O2 were proposed to be the main oxidants of the CuO@C/PMS system, and the possible intermediates were also fully investigated. Moreover, a catalytic cycle involving Cu+/Cu2+/Cu3+ was proposed. It was also demonstrated that the highly stable CuO@C can be easily recycled and reused. The present study therefore embodies the conceptual design of an excellent catalyst with a persistent stability for the activation of PMS, which may serve as a versatile platform for wider environmental applications.

Enhancing and Mitigating Radiolytic Damage to Soft Matter in Aqueous Phase Liquid-Cell Transmission Electron Microscopy in the Presence of Gold Nanoparticle Sensitizers or Isopropanol Scavengers.

In this work, we describe the radiolytic environment experienced by a polymer in water during liquid-cell transmission electron microscopy (LCTEM). We examined the radiolytic environment of aqueous solutions of poly(ethylene glycol) (PEG, 2400 g/mol) in the presence of sensitizing gold nanoparticles (GNPs, 100 nm) or radical scavenging isopropanol (IPA). To quantify polymer damage, we employed post-mortem analysis via matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). This approach confirms IPA (1-10% w/v) can significantly mitigate radiolysis-induced damage to polymers in water, while GNPs significantly enhance damage. We couple LCTEM experiments with simulations to provide a generalizable strategy for assessing radiolysis mitigation or enhancement. This study highlights the caution required for LCTEM experiments on inorganic nanoparticles where solution phase properties of surrounding organic materials or the solvent itself are under investigation. Furthermore, we anticipate an increased use of scavengers for LCTEM studies of all kinds.

Characterization of composite material from the copolymerized polyphenolic matrix with treated cassava peels starch

Conventional binders in the particleboards formulation involve use of formaldehyde resins. Epidemiologic studies show that formaldehyde is carcinogenic. Efforts to reduce formaldehyde emissions by use of scavengers has not been proven to reduce the emission. Molecular bonding of biobased adhesive molecules with lignocellulose materials provides an alternative way of producing composite material. In this study, maize stalk (MS), rice husks (RH) and sugarcane bagasse (SB) were used as sources of lignocellulose materials for particleboard formulation. SB, MS and RH were collected from their respective sites, sorted and dried. MS and RH were ground. Lignin content determination was done by drying lignocellulose material at 105 °C. Lignocellulose materials were prepared by hydrolysis of dried lignocellulose material with sodium hydroxide. Oxidized starch was prepared by oxidation of cassava peel starch using alkaline hydrogen peroxide. Particleboards were formulated through starch-lignocellulose polymerization at 60 °C compressed with 6.5 Nmm−2 pressure. Characterization of raw materials and formulated particleboards was done using XRD for mineralogical analysis, FTIR and NMR for elucidation of functional groups transformation. The results showed that esterification is the main process of chemical bonding in the particleboard formulation due to reaction between –COOH from starch and and OH- from lignocellulose. Etherification between hydroxyl groups from starch with hydroxyl groups from lignocellulose material. RH combined more through silication process with cassava peels starch than RH and SB showing materials containing high cellulose and hemicellulose content are more compatible. Composite materials formulated were used to produce medium density particleboards that can be used for making furniture and room partitioning.

Electrochemically assisted decomposition of ozone for degradation and mineralization of Diuron

In this work, we explore the possibility of enhancing the ozonation of a solution of Diuron by combination with electrochemical processes. To this aim, the ozonation was performed in a membrane free electrolyzer where a reticulated vitreous carbon (RVC) and a stainless steel (SS) cathode have been alternatively tested and compared. The effect of pH, current density and ozone flow on degradation and mineralization of Diuron has been investigated. The involvement of radical species has been verified by means of test conducted with selective scavenging agents.The results show that both cathodes can promote the decomposition of ozone and therefore the degradation of Diuron. The use of scavengers has shown that the removal of Diuron is driven by means of radical species. Depending on the adopted materials, different mechanisms occur and different operating conditions are required. In particular, the use of a carbon-based cathode implies the production of hydrogen peroxide and therefore the occurrence of an Electro-peroxone process, which is favored at alkaline pH and low current values. On the other hand, the adoption of a metal cathode, whose efficiency is highly promoted by acidic pH and high currents, implies the direct reduction of ozone with the production of hydroxyl radicals.

Formaldehyde Use and Alternative Biobased Binders for Particleboard Formulation: A Review

Formaldehyde-based resins are conventionally used as a binder in formulation of particleboard. Epidemiologic studies have shown that formaldehyde is carcinogenic. Efforts to reduce the health hazard effects of the fomaldehyde-based resin in the particleboard formulation have included use of scavengers for formaldehydes and use of an alternative binder. Use of scavengers for the formaldehyde increases the cost and maintenance of particleboard formulation. There is no proof that scavengers eliminate the emission of formaldehyde from particleboard. Use of biobased binders in particleboard formulation provides an alternative for eliminating use of the formaldehyde-based resin. However, the alternative is hindered by challenges, which include limitations of physical and mechanical properties. The challenge has continuously been acted upon through research. The paper presents an overview of the use of starch as an alternative binder. Improvement over time of the starch and limitations thereof requires to be addressed. Use of the modified starch has shown increased particleboard performance. Mechanical strength, such as modulus of rupture, modulus of elasticity, and internal bonding in particleboards, however, remains to be a challenge.

Modeling of petroleum wastewater treatment by Fe/Zn nanoparticles using the response surface methodology and enhancing the efficiency by scavenger

The petroleum wastewater caused to serious problems in the aqueous and soil environments, therefore treatment of petroleum wastewater has extremely been in the center of attention in recent years. Phenol is one of main petroleum compounds. The photocatalytic removal of phenol from the wastewater by the use of scavenger and nanoparticle is discussed in this research. In this research, Fe/Zn bimetal nanoparticle is synthesized and used by a new and simple method. Based on the results, this nanoparticle has solved the issue of its removal from the water (after the treatment) using its exclusive magnetic property. Using the Hydrogen peroxide as a scavenger has significantly increased the efficiency of the nanoparticle in photocatalytic treatment. The independent parameters studied in this research include the phenol initial concentration, light source power, retention time, pH and the nanocatalysts concentration. The Hydrogen peroxide was used with the constant concentration of 0.01 M. The experiment design was performed by response surface methodology. Based on the results, the removal efficiency was increased by increasing in nanocatalyst concentration, pH, UV source power and retention time. Also removal efficiency decreased by increasing in initial phenol concentration. According to the FESEM result, nanomaterial has dimensions less than 50 nm. The removal efficiency has been obtained as 89% in the optimum condition (pH equal to 5.23, light source power equal to 43.53 w, phenol concentration equal to 50 ppm, Nano concentration equal to 1.57 g/l and the time equal to 58.6 min).

DNA interactions and anticancer screening of copper(II) complexes of N-(methylpyridin-2-yl)-amidino-O-methylurea

Cu(II) complexes of the tridentate ligand N-(methylpyridin-2-yl)-amidino-O-methylurea (L), namely [Cu(L)Cl2] and [Cu(L)ClO4]ClO4, have been investigated for interactions with DNA by spectroscopic methods and viscosity measurements. Both complexes bind to DNA through non-intercalative interactions. [Cu(L)Cl2] (K b = 2.81 × 105 M−1) shows similar DNA-binding potential to [Cu(L)ClO4]ClO4 (K b = 1.57 × 105 M−1). Investigation of the chemical nuclease properties toward plasmid pBR322 DNA by gel electrophoresis and atomic force microscopy (AFM) suggests that both complexes are able to cleave the supercoiled form (Form I) to the nicked (Form II) and linear forms (Form III) through an oxidative pathway. The possible reactive oxygen species have been investigated by the use of scavengers, indicating that hydroxyl radicals may be involved in the DNA cleavage mechanism. Both of these complexes show similar activities against selected human cancer cell lines.

Reactive Carbonyl Species Scavengers-Novel Therapeutic Approaches for Chronic Diseases.

To summarize recent evidence supporting the use of reactive carbonyl species scavengers in the prevention and treatment of disease. The newly developed 2-aminomethylphenol class of scavengers shows great promise in preclinical trials for a number of diverse conditions including neurodegenerative diseases and cardiovascular disease. In addition, new studies with the thiol-based and imidazole-based scavengers have found new applications outside of adjunctive therapy for chemotherapeutics. Reactive oxygen species (ROS) generated by cells and tissues act as signaling molecules and as cytotoxic agents to defend against pathogens, but ROS also cause collateral damage to vital cellular components. The polyunsaturated fatty acyl chains of phospholipids in the cell membranes are particularly vulnerable to damaging peroxidation by ROS. Evidence suggests that the breakdown of these peroxidized lipids to reactive carbonyls species plays a critical role in many chronic diseases. Antioxidants that abrogate ROS-induced formation of reactive carbonyl species also abrogate normal ROS signaling and thus exert both beneficial and adverse functional effects. The use of scavengers of reactive dicarbonyl species represent an alternative therapeutic strategy to potentially mitigate the adverse effects of ROS without abrogating normal signaling by ROS. In this review, we focus on three classes of reactive carbonyl species scavengers: thiol-based scavengers (2-mercaptoethanesulfonate and amifostine), imidazole-based scavengers (carnosine and its analogs), and 2-aminomethylphenols-based scavengers (pyridoxamine, 2-hydroxybenzylamine, and 5'-O-pentyl-pyridoxamine) that are either undergoing pre-clinical studies, advancing to clinical trials, or are already in clinical use.

Disinfection and Mechanistic Insights of Escherichia coli in Water by Bismuth Oxyhalide Photocatalysis.

This study demonstrates the potential of a new BiOCl0.875 Br0.125 photocatalyst to disinfect Escherichia coli in water under simulated solar irradiation. Photocatalytic efficiency was examined for different photocatalyst loadings, solar wavelengths, exposure times, photocatalyst concentration × contact time (Ct) concept and with the use of scavengers. To elucidate the inactivation mechanism, we examined DNA damage, membrane damage, lipid peroxidation and protein release. Both photolysis and photocatalysis were negligible under visible irradiation, but enhanced photocatalytic activity was observed under solar UVA (λ > 320 nm) and UVB (λ > 280 nm), with 1.5 and 3.6 log inactivation, respectively, after 40 min of irradiation. The log inactivation vs Ct curve for E. coli by UVA/BiOCl0.875 Br0.125 was fairly linear, with Ct = 10 g L-1 × min, resulting in 2 log inactivation. Photocatalytic treatment led to membrane damage, but without lipid peroxidation. Accordingly, protein was released from the cells after UVA or UVA/BiOCl0.875 Br0.125 treatment. Photocatalysis also increased endonuclease-sensitive sites vs photolysis alone, by an unknown mechanism. Finally, E. coli inactivation was not influenced by the addition of tert-butanol or l-histidine, implying that neither hydroxyl radicals nor singlet oxygen reactive species are involved in the inactivation process.

Models of marine molluscan diseases: Trends and challenges

Disease effects on host population dynamics and the transmission of pathogens between hosts are two important challenges for understanding how epizootics wax and wane and how disease influences host population dynamics. For the management of marine shellfish resources, marine diseases pose additional challenges in early intervention after the appearance of disease, management of the diseased population to limit a decline in host abundance, and application of measures to restrain that decline once it occurs. Mathematical models provide one approach for quantifying these effects and addressing the competing goals of managing the diseased population versus managing the disease. The majority of models for molluscan diseases fall into three categories distinguished by these competing goals. (1) Models that consider disease effects on the host population tend to focus on pathogen proliferation within the host. Many of the well-known molluscan diseases are pandemic, in that they routinely reach high prevalence rapidly over large geographic expanses, are characterized by transmission that does not depend upon a local source, and exert a significant influence on host population dynamics. Models focused on disease proliferation examine the influence of environmental change on host population metrics and provide a basis to better manage diseased stocks. Such models are readily adapted to questions of fishery management and habitat restoration. (2) Transmission models are designed to understand the mechanisms triggering epizootics, identify factors impeding epizootic development, and evaluate controls on the rate of disease spread over the host’s range. Transmission models have been used extensively to study terrestrial diseases, yet little attention has been given to their potential for understanding the epidemiology of marine molluscan diseases. For management of diseases of wild stocks, transmission models open up a range of options, including the application of area management, manipulation of host abundance, and use of scavengers and filter feeders to limit the concentration of infective particles. (3) The details of host population processes and pathogen transmission dynamics are blended in models that evaluate the effects of natural selection and/or genetic modification in developing disease resistance in the host population. Application of gene-based models to marine diseases is only now beginning and represents a promising approach that may provide a mechanistic basis for managing marine diseases and their host populations. Overall disease models remain both uncommon and underutilized in addressing the needs for managing molluscan diseases and their host populations.

Determination of main species involved in the first steps of TiO2 photocatalytic degradation of organics with the use of scavengers: The case of ofloxacin

With the aid of different scavengers species involved in the first steps of TiO2/UVA (black light) photocatalytic elimination of ofloxacin (OFX) in water have been investigated. The effect of the presence of scavengers of hydroxyl radicals in bulk water (t-butanol), oxidant holes (h+) (2-propanol, iodide and oxalate), singlet oxygen (azide), electrons (oxygen) and superoxide ion radical (p-benzoquinone and tiron) has been checked at pH 7 with 0.03M HClO4/ClO4− aerated media. The main elimination pathway leads to the formation of OFX+ and takes place through an electronic transfer between the antibiotic and the catalyst surface. OFX+ further reacts with O2− leading to the reductive demethylation of OFX and generates 1mole of hydrogen peroxide and ∼1mole of formaldehyde per mole of OFX eliminated. The presence of phosphate promotes a change in the pathway degradation, possibly favoring the generation of HO radicals as well as the participation of this species on the oxidative demethylation of OFX and therefore reduces the production of H2O2. Therefore, OFX can be photocatalytically reduced and/or oxidized depending on the experimental conditions.

Food predictability determines space use of endangered vultures: implications for management of supplementary feeding.

Understanding space use of free-living endangered animals is key to informing management decisions for conservation planning. Like most scavengers, vultures have evolved under a context of unpredictability of food resources (i.e., exploiting scattered carcasses that are intermittently available). However, the role of predictable sources of food in shaping spatial ecology of vultures has seldom been studied in detail. Here, we quantify the home range of the Egyptian Vulture (Neophron percnopterus), a long-lived raptor that has experienced severe population decline throughout its range and is qualified as endangered worldwide. To this end, six adults were tracked by satellite telemetry in Spain during the breeding season, from 2007 to 2012, recording 10360 GPS locations. Using Resource Utilization Functions, we assessed the topology of the Utilization Distribution, a three-dimensional measure that shows the probability of finding an animal within the home range. Our results showed how food availability, and principally, how food predictability, determines ranging behavior of this species. Egyptian Vultures showed consistent site fidelity across years, measured as the two- and three-dimensional overlap in their home ranges. Space use varied considerably within the home range and remarkably, places located far from nesting sites were used more frequently than some areas located closer. Therefore, traditional conservation measures based on establishing restrictive rules within a fixed radius around nesting sites could be biologically meaningless if other areas within the home range are not protected too. Finally, our results emphasize the importance of anthropogenic predictable sources of food (mainly vulture restaurants) in shaping the space use of scavengers, which is in agreement with recent findings. Hence, measures aimed at ensuring food availability are essential to preserve this endangered vulture, especially in the present context of limiting carrion dumping in the field due to sanitary regulations according to European legislation.

A mechanistic study on the cardiotoxicity of 5-fluorouracil in vitro and clinical and occupational perspectives

Fluoropyrimidines are key agents for the treatment of gastrointestinal tract adenocarcinomas. The possible cardiotoxic effects in patients and occupationally exposed workers are multifactorial and remain a puzzle to solve for investigators. In the present study, we study what cell death pathways and what doses can determine direct cardiotoxic effects of 5-fluorouracil (5-FU) and doxorubicin (DOXO) on rat cardiocytes (H9c2) and a human colon adenocarcinoma (HT-29) cell line, already reported to be sensitive to 5-FU. We have found that 5-FU induced 50% growth inhibition (IC:50) at 72h with concentrations of 400μM and 4μM on H9c2 and HT-29, respectively. Moreover, we have found that the addition of Levofolinic Acid (LF) to 5-FU potentiated the growth inhibition induced by 5-FU. The growth inhibition induced by 5-FU alone or in combination with LF in cardiocytes was paralleled by an increase of thiobarbituric acid-reactive species (Tbars) and end products of nitric oxide (NO) suggesting the increase of the oxidative stress status in cardiocytes. Interestingly, these effects were strongly potentiated by the addition of LF, a biochemical modulator of 5-FU activity.Our data suggest that agents such as 5-FU different from anthracyclines, conventionally related to the induction of cardiotoxic effects, can also induce cardiocyte damage paralleled by oxidative stress. The strategies based upon the use of scavengers could be used in order to prevent this effect.

On the spur lifetime and its temperature dependence in the low linear energy transfer radiolysis of water

In the spirit of the radiation chemical "spur model", the lifetime of a spur (τ(s)) is an important indicator of overlapping spurs and the establishment of homogeneity in the distribution of reactive species created by the action of low linear energy transfer (LET) radiation (such as fast electrons or γ irradiation). In fact, τ(s) gives the time required for the changeover from nonhomogeneous spur kinetics to homogeneous kinetics in the bulk solution, thus defining the so-called primary (or "escape") radical and molecular yields of radiolysis, which are obviously basic to the quantitative understanding of any irradiated chemical system. In this work, τ(s) and its temperature dependence have been determined for the low-LET radiolysis of deaerated 0.4 M aqueous solutions of H(2)SO(4) and pure liquid water up to 350 °C using a simple model of energy deposition initially in spurs, followed by random diffusion of the species of the spur during track expansion until spur overlap is complete. Unlike our previous τ(s) calculations, based on irradiated Fricke dosimeter simulations, the current model is free from any effects due to the presence of oxygen or the use of scavengers. In acidic solutions, the spur lifetime values thus obtained are in very good agreement with our previous calculations (after making appropriate corrections, however, to account for the possibility of competition between oxygen and Fe(2+) ions for H˙ atoms in the Fricke dosimeter, an effect which was not included in our original simulations). In this way, we confirm the validity of our previous approach. As expected, in the case of pure, oxygen-free water, our calculated times required to reach complete spur overlap are essentially the same (within uncertainty limits) as those found in acidic solutions. This explicitly reflects the fact that the diffusion coefficients for the hydrated electron and the H˙ atom that are involved in the overall calculation of the lifetime of spurs in neutral or acidic media, respectively, are of similar magnitude over the 25-350 °C temperature range studied.

Photo Catalytic water treatment by an eco friendly processBaO3TiO.SrO3TiO used in degradation of Malachite green and Crystal violet in aqueous suspension

Commercially used dyes Malachite green and Crystal violet are toxic for human health . These dyes were removed through photo catalytic degradation using a new semiconductor Barium strontium titanate (Ba3TiO.SrO3TiO). The maximum degradation conditions were established by varying various factor like pH, intensity of light, concentration of dyes, amount of semiconductor etc. It was observed on kinetic parameters that the process follows pseudo first order rate law. The degraded products formed were NO2 , CO2, H2O etc which were nontoxic in nature. The mechanism was confirmed to be a free radical one by use of scavenger.