Electron Magnetic Resonance Study of Ni50.2Mn28.3Ga21.5 Powders.

In the present paper, we present an electron magnetic resonance (EMR) study of Ni50.2Mn28.3Ga21.5 powders obtained from melt-spun ribbons in the milling process. We registered EMR spectra in various temperatures at the X-band. In the EMR spectra recorded for the samples taken at the beginning of the milling process, the "training effect" was observed. After 2 h of milling, this phenomenon was no longer observed. To determine the basic EMR parameters, such as linewidth, resonance field, and asymmetry parameters, the experimental data were fitted using a single metallic Lorentz line. In high-temperature regions, we observed the influence of dispersion on the shape of the spectra, but as the temperature decreased, the asymmetry of line was reduced. The shift in the resonance field value at high temperatures and the temperature dependence of the linewidth below Curie temperature indicate that the investigated samples exhibited a characteristics of a spin-glass alloy.

Photocatalytic and antibacterial activity properties of Ti surface treated by femtosecond laser-a prospective solution to peri-implant disease.

Laser texturing seems to be a promising technique for reducing bacterial adhesion on titanium implant surfaces. This work aims to demonstrate the possibility of obtaining a functionally orientated surface of titanium implant elements with a specific architecture with specific bacteriological and photocatalytic properties. Femtosecond laser-generated surface structures, such as laser-induced periodic surface structures (LIPSS, wrinkles), grooves, and spikes on titanium, have been characterised by XRD, Raman spectroscopy, and scanning electron microscopy (SEM). The photocatalytic activity of the titanium surfaces produced was tested based on the degradation effect of methylene blue (MB). The correlation between the photocatalytic activity of TiO2 coatings and their morphology and structure has been analysed. Features related to the size, shape, and distribution of the roughness patterns were found to influence the adhesion of the bacterial strain on different surfaces. On the laser-structurised surface, the adhesion of Escherichia coli bacteria were reduced by 80% compared to an untreated reference surface.

Effect of Garlic Extract on the Erythrocyte as a Simple Model Cell.

Garlic is known to have diverse effects on mammalian cells, being cytotoxic, especially to cancer cells, but also protect against oxidative stress. Mammalian erythrocyte is a simple cell devoid of intracellular organelles, protein synthesis ability, and most signaling pathways. Therefore, examination of the effects of garlic on erythrocytes allows for revealing primary events in the cellular action of garlic extract. In this study, human erythrocytes or erythrocyte membranes were exposed to garlic extract at various dilutions. Hemoglobin oxidation to methemoglobin, increased binding of hemoglobin to the membrane, and formation of Heinz bodies were observed. Garlic extract depleted acid-soluble thiols, especially glutathione, and induced a prooxidative shift in the cellular glutathione redox potential. The extract increased the osmotic fragility of erythrocytes, induced hemolysis, and inhibited hemolysis in isotonic ammonium chloride, indicative of decreased membrane permeability for Cl- and increased the membrane fluidity. Fluorescent probes indicated an increased level of reactive oxygen species and induction of lipid peroxidation, but these results should be interpreted with care since the extract alone induced oxidation of the probes (dichlorodihydrofluorescein diacetate and BODIPY C11). These results demonstrate that garlic extract induces oxidative changes in the erythrocyte, first of all, thiol and hemoglobin oxidation.

Effect of Low Concentration of Nitroxides on SH-SY5Y Cells Transfected with the Tau Protein.

Nitroxides, stable synthetic free radicals, are promising antioxidants, showing many beneficial effects both at the cellular level and in animal studies. However, the cells are usually treated with high millimolar concentrations of nitroxides which are not relevant to the concentrations that could be attained in vivo. This paper aimed to examine the effects of low (≤10 µM) concentrations of three nitroxides, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), 4-hydroxy-TEMPO (TEMPOL) and 4-amino-TEMPO (TEMPAMINE), in pure chemical systems and on SH-SY5Y cells transfected with the human tau protein (TAU cells), a model of chronic cellular oxidative stress, and transfected with the empty plasmid (EP cells). All nitroxides were active in antioxidant-activity tests except for the 2,2'-azinobis-(3-ethylbenzthiazolin-6-sulfonate) radical (ABTS•) decolorization assay and reduced Fe3+, inhibited autoxidation of adrenalin and pyrogallol and oxidation of dihydrorhodamine123 by 3-morpholino-sydnonimine SIN-1. TEMPO protected against fluorescein bleaching from hypochlorite, but TEMPAMINE enhanced the bleaching. Nitroxides showed no cytotoxicity and were reduced by the cells to non-paramagnetic derivatives. They decreased the level of reactive oxygen species, depleted glutathione, and increased mitochondrial-membrane potential in both types of cells, and increased lipid peroxidation in TAU cells. These results demonstrate that even at low micromolar concentrations nitroxides can affect the cellular redox equilibrium and other biochemical parameters.

Characteristics of Adsorption/Desorption Process on Dolomite Adsorbent in the Copper(II) Removal from Aqueous Solutions.

The removal of hazardous heavy metals that have been released into the environment due to industrial activities has become an important issue in recent years. The presented study concerned the removal of copper(II) ions from aqueous solutions using dolomites. Dolomite is a very attractive adsorbent due to its wide availability, low cost, good adsorption, and environmental compatibility. The paper describes the properties of D-I and D-II dolomites from two different open-cast mines in Poland. The properties of natural adsorbents were determined based on point of zero charges (PZC), elemental analysis of the adsorbent composition, FT-IR, XRD, and SEM spectra analysis. Depending on the initial concentration of the solution used, the adsorption efficiency of copper(II) ions was 58-80% for D-I and 80-97% for D-II. The adsorption mechanism in the case of D-II dolomite was mainly based on ion exchange, while chemisorption dominated the D-I dolomite surface. Considering the possibility of the regeneration and reuse of the adsorbent, dolomite D-II is a better material (the desorption efficiency of copper(II) ions was 58-80%). The adsorption behavior of dolomites has been described using six adsorption isotherms. The best fit was obtained for the Redlich-Peterson, Jovanovic, and Langmuir isotherms, indicating that monolayer adsorption occurred. The maximum adsorption capacity for copper(II) was 378 mg/g of D-I and 308 mg/g of D-II.

Significance of MnO2 Type and Solution Parameters in Manganese Removal from Water Solution.

A very low concentration of manganese (Mn) in water is a critical issue for municipal and industrial water supply systems. Mn removal technology is based on the use of manganese oxides (MnOx), especially manganese dioxide (MnO2) polymorphs, under different conditions of pH and ionic strength (water salinity). The statistical significance of the impact of polymorph type (akhtenskite ε-MnO2, birnessite δ-MnO2, cryptomelane α-MnO2 and pyrolusite ß-MnO2), pH (2-9) and ionic strength (1-50 mmol/L) of solution on the adsorption level of Mn was investigated. The analysis of variance and the non-parametric Kruskal-Wallis H test were applied. Before and after Mn adsorption, the tested polymorphs were characterized using X-ray diffraction, scanning electron microscope techniques and gas porosimetry analysis. Here we demonstrated the significant differences in adsorption level between MnO2 polymorphs' type and pH; however, the statistical analysis proves that the type of MnO2 has a four times stronger influence. There was no statistical significance for the ionic strength parameter. We showed that the high adsorption of Mn on the poorly crystalline polymorphs leads to the blockage of micropores in akhtenskite and, contrary, causes the development of the surface structure of birnessite. At the same time, no changes in the surfaces of cryptomelane and pyrolusite, the highly crystalline polymorphs, were found due to the very small loading by the adsorbate.

Zinc-Cobalt Oxide Thin Films: High Curie Temperature Studied by Electron Magnetic Resonance.

The material with a high Curie temperature of cobalt-doped zinc oxide embedded with silver-nanoparticle thin films was studied by electron magnetic resonance. The nanoparticles were synthesized by the homogeneous nucleation technique. Thin films were produced with the pulsed laser deposition method. The main aim of this work was to investigate the effect of Ag nanoparticles on the magnetic properties of the films. Simultaneously, the coexisting Ag0 and Ag2+ centers in zinc oxide structures are shown. A discussion of the signal seen in the low field was conducted. To analyze the temperature dependence of the line parameters, the theory described by Becker was used. The implementation of silver nanoparticles causes a significant shift of the line, and the ferromagnetic properties occur in a wide temperature range with an estimated Curie temperature above 500 K.

Photocatalytic activity of layered MoS2 in the reductive degradation of bromophenol blue.

Molybdenum disulphide (MoS2) is a layered material with interesting photocatalytic properties. In this study, a layered MoS2 was produced using a hydrothermal method. The obtained material was characterised by XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscopy), UV-Vis spectroscopy, DLS (dynamic light scattering), and zeta potential analysis. For the evaluation of the photocatalytic properties of layered MoS2, a solution of bromophenol blue (BPB) and the catalyst was illuminated for 120 minutes. According to the experimental results, MoS2 exhibited excellent catalytic activity in BPB degradation. The MoS2 preparation method enabled improved light harvesting, avoided fast charge recombination (related to bulk MoS2), and created a large number of suitable electron transfer sites for photocatalytic reactions. Simulation of BPB decay and bromide production was carried out for a further understanding of MoS2 photocatalytic action. The simulation results proved the reduction mechanism of BPB photodegradation.

Electron Paramagnetic Resonance Study of PbSe, PbTe, and PbTe:In Semiconductors Obtained by the Pulsed Laser Deposition Method.

The magnetic properties of lead selenide (PbSe) and indium-doped lead telluride (PbTe:In) composites have been studied by using the electron paramagnetic resonance (EPR) technique. The samples were obtained by using the pulsed laser deposition method (PLD). Temperature dependences of the EPR spectra were obtained. The analysis of the temperature dependencies of the integral intensity of the EPR spectra was performed using the Curie-Weiss law. In these materials, the paramagnetic centers of Pb1+ and Pb3+ ions were identified. The results are discussed.

Characteristics of the Properties of Absodan Plus Sorbent and Its Ability to Remove Phosphates and Chromates from Aqueous Solutions.

The aim of the research was to characterize the parameters of the diatomite sorbent Absodan Plus as well as to assess its suitability for the adsorption of chromates and phosphates from acidic aqueous solutions simulating the conditions occurring in some types of industrial wastewater. The scope of the research includes XRD, SEM, BET, and PZC analyses, and 3D observation of commercial diatomite granules and batch tests to determine the constants of kinetics and the equilibrium of chromates and phosphates adsorption. Absodan Plus is a diatomite commercial material containing an amorphous phase (33%) and is also the crystalline phase of quartz, hematite, and grossite. The material is macro- and mesoporous and its specific surface area is about 30 m2/g. Its PZC is around pH = 5.5-6.0 and in an acidic environment is able to adsorb the anions. The saturation of the adsorbent surface with molecules of the adsorbed substance occurs after 2 h for chromates and 2.5 h for phosphates. The maximum adsorption capacity of Absodan Plus in terms of phosphorus and chromium amounts to 9.46 mg P/g and 39.1 mg Cr/g, respectively. As shown by XRD analysis, Absodan Plus contains an admixture of hematite, which can support the removal of chromium and phosphorus.

Synthesis of Micro-Spikes and Herringbones Structures by Femtosecond Laser Pulses on a Titanium Plate-A New Material for Water Organic Pollutants Degradation.

(1) Background: The shrinkage of water resources, as well as the deterioration of its quality as a result of industrial human activities, requires a comprehensive approach relative to its protection. Advanced oxidation processes show high potential for the degradation of organic pollutants in water and wastewater. TiO2 is the most popular photocatalyst because of its oxidizing ability, chemical stability and low cost. The major drawback of using it in powdered form is the difficulty of separation from the reaction mixture. The solution to this problem may be immobilization on a support (glass beads, molecular sieves, etc.). In order to avoid these difficulties, the authors propose to prepare a catalyst as a titanium plate covered with an oxide layer obtained with laser treatment. (2) Methods: In the present work, we generated titanium oxide structures using a cheap and fast method based on femtosecond laser pulses. The structurized plates were tested in the reaction of methylene blue (MB) degradation under UVA irradiation (365 nm). The photocatalytic activity and kinetic properties for the degradation of MB are provided. (3) Results: Studies of X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm a titanium oxide layer with laser-induced generated structures that are called "spikes" and "herringbones". The structurized plates were effective photocatalysts, and their activity depends on the structure of the oxide layer (spike and herringbone). (4) Conclusions: The immobilization of the catalyst on a solid support can be performed in a fast and reproducible manner by using the technique of laser ablation. The layers obtained with this method have been shown to have catalytic properties.

EPR Spectra of Sintered Cd1-xCrxTe Powdered Crystals with Various Cr Content.

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1-xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie-Weiss law and the paramagnetic Curie temperature was obtained.

Nitroxide Radical-Containing Redox Nanoparticles Protect Neuroblastoma SH-SY5Y Cells against 6-Hydroxydopamine Toxicity.

Parkinson's disease (PD) patients can benefit from antioxidant supplementation, and new efficient antioxidants are needed. The aim of this study was to evaluate the protective effect of selected nitroxide-containing redox nanoparticles (NRNPs) in a cellular model of PD. Antioxidant properties of NRNPs were studied in cell-free systems by protection of dihydrorhodamine 123 against oxidation by 3-morpholino-sydnonimine and protection of fluorescein against bleaching by 2,2-azobis(2-amidinopropane) hydrochloride and sodium hypochlorite. Model blood-brain barrier penetration was studied using hCMEC/D3 cells. Human neuroblastoma SH-SY5Y cells, exposed to 6-hydroxydopamine (6-OHDA), were used as an in vitro model of PD. Cells were preexposed to NRNPs or free nitroxides (TEMPO or 4-amino-TEMPO) for 2 h and treated with 6-OHDA for 1 h and 24 h. The reactive oxygen species (ROS) level was estimated with dihydroethidine 123 and Fluorimetric Mitochondrial Superoxide Activity Assay Kit. Glutathione level (GSH) was measured with ortho-phtalaldehyde, ATP by luminometry, changes in mitochondrial membrane potential with JC-1, and mitochondrial mass with 10-Nonyl-Acridine Orange. NRNP1, TEMPO, and 4-amino-TEMPO (25-150 µM) protected SH-SY5Y cells from 6-OHDA-induced viability loss; the protection was much higher for NRNP1 than for free nitroxides. NRNP1 were better antioxidants in vitro and permeated better the model BBB than free nitroxides. Exposure to 6-OHDA decreased the GSH level after 1 h and increased it considerably after 24 h (apparently a compensatory overresponse); NRNPs and free nitroxides prevented this increase. NRNP1 and free nitroxides prevented the decrease in ATP level after 1 h and increased it after 24 h. 6-OHDA increased the intracellular ROS level and mitochondrial superoxide level. Studied antioxidants mostly decreased ROS and superoxide levels. 6-OHDA decreased the mitochondrial potential and mitochondrial mass; both effects were prevented by NRNP1 and nitroxides. These results suggest that the mitochondria are the main site of 6-OHDA-induced cellular damage and demonstrate a protective effect of NRNP1 in a cellular model of PD.

Interaction of Catechins with Human Erythrocytes.

The aim of this study was to characterize the interaction of chosen catechins ((+)-catechin, (-)-epigallocatechin (EGC), and (-)-epigallocatechin gallate (EGCG)) with human erythrocytes and their protective effects against oxidative damage of erythrocytes. Uptake of the catechins by erythrocytes was studied by fluorimetry, their interaction with erythrocyte membrane was probed by changes in erythrocyte osmotic fragility and in membrane fluidity evaluated with spin labels, while protection against oxidative damage was assessed by protection against hemolysis induced by permanganate and protection of erythrocyte membranes against lipid peroxidation and protein thiol group oxidation. Catechin uptake was similar for all the compounds studied. Accumulation of catechins in the erythrocyte membrane was demonstrated by the catechin-induced increase in osmotic resistance and rigidification of the erythrocyte membrane detected by spin labels 5-doxyl stearic acid and 16-doxyl stearic acid. (-)-Epigallocatechin and EGCG inhibited erythrocyte acetylcholinesterase (mixed-type inhibition). Catechins protected erythrocytes against permanganate-induced hemolysis, oxidation of erythrocyte protein thiol groups, as well as membrane lipid peroxidation. These results contribute to the knowledge of the beneficial effects of catechins present in plant-derived food and beverages.

Tempo-phosphate as an ESR tool to study phosphate transport.

TEMPO-phosphate has been introduced as a phosphate analogue to study phosphate transport in erythrocytes. The nitroxide is reduced intracellularly upon entering the cells, the membrane transport being the rate-limiting step of the loss of ESR signal. The use of TEMPO-phosphate is convenient and avoids the hazard of radioactivity. We studied the inhibition of TEMPO-phosphate transport to human erythrocytes by various compounds. DIDS and SITS, inhibitors of Band 3, inhibited the TEMPO-phosphate transport. 1-cyano-4-hydroxycinnamic acid, inhibitor of monocarboxylate transporters, did not affect the permeation of TEMPO-phosphate. The transport of TEMPO-phosphate was inhibited by various polyphenols, especially curcumin, naringin, quercetin, luteolin and kaempferol. Interestingly, 3-bromopyruvic acid, an alkylating agent and potential anticancer agent, induced an apparent enhancement of TEMPO-phosphate transport into erythrocytes.