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Aldehydes, such as benzaldehyde, are very important in many industries and can be prepared from alcohols. In this research, aluminium oxide-pillared bentonite (Al-PILC) was prepared by inserting aluminium (III) chloride into the interlayers and calcination. Then PdCl2 was impregnated into Al-PILC and calcined to produce Pd/Al-PILC. The synthesized clay and raw clay were characterized by X-ray diffraction (XRD) and N2 adsorption-desorption (Brunauer-Emmett-Teller; BET) techniques. From the characterization, XRD pattern exhibited the characteristic peaks of montmorillonite at 2θ of 7° and 22°. Additionally, the N2 adsorption-desorption isotherm of Pd/Al-PILC indicated mesoporous structure and BET specific surface area was 102 m2/g. The catalytic activity of Pd/Al-PILC was investigated for the oxidation of benzyl alcohol with H2O2 furnishing benzaldehyde. In the optimum condition, 82% of benzaldehyde was produced via the reaction of benzyl alcohol and H2O2 in the presence of a catalytic amount of Pd/Al-PILC in refluxing acetonitrile for 3 h under mild reaction conditions.

In this work, PVDF membranes coated with ZnO particles were prepared to study the influence of the loading concentration on RhB pollutant removal. The PVDF membranes prepared by phase inversion method contain a mixture of α and β phases as identified by correlating the XRD and FT-IR results. The mean pore size evaluated by SEM measurements is about 4 μm and the asymmetric structure of the membrane was highlighted. The presence of ZnO particles on PVDF membrane was evidenced by XRD, SEM and EXD measurements. By coating with ZnO particles the hydrophilic character of the membrane was improved. The RhB removal was realized using a combined process of two competitive methods: adsorption and photocatalysis. By increasing the ZnO loading the removal efficiency was enhanced. Additionally, the electron spin resonance spectroscopy coupled with spin trapping technique was used to evidence the generation of reactive oxygen species during irradiation, the presence of both hydroxyl radical and superoxide radical being proven.

The MnO2 nanoparticles, when used as catalyst, determine an enhanced reaction rate of the transesterifications process thus being very attractive for biodiesel production. One of the current limitations of the biofuel production by using MnO2 nanoparticles as catalyst is given by the reaction conditions. This work intends to improve the transesterification reaction efficiency through the use of a microwave field. It can generate large quantities of energy that lead to a good molecular motion thus favoring the transesterification process without altering the molecular structure. The aim of the present research is to explore the possibility of carrying out the microwave-assisted transesterification of grapes residues and seeds oil through the use of MnO2 nanoparticles as catalysts, as well as yeast (Saccharomyces cerevisiae), to efficiently obtain biofuel end product. Both chemically and biochemically (using plant extracts) synthesized MnO2 nanoparticles were produced and characterized by different techniques like TEM, XRD, BET, XPS, VSM. The analysis of obtained biofuel was performed by GC–MS. The comparison of results revealed that the samples prepared using plant extracts have morphologic properties higher than chemically prepared sample. MnO2 nanoparticles obtained by the use of oregano extracts were further tested for microwave assisted transesterification studies. The surface area of the MnO2 nanoparticles biochemically synthesized was four times higher than the nanoparticles synthesized by chemical method. The MnO2-oregano nanoparticles presented the best catalytic activity for biodiesel production as compared to the yeast catalyst. The use of microwave field for transesterification further enhances the efficiency of the process.

New tellurite glasses of the xMnO(100-x)TeO2 system with x = 0–26.2 mol % were prepared by sol-gel method. X-ray diffraction and FTIR, UV–Vis, electron paramagnetic resonance (EPR) and photoluminescence (PL) spectroscopies were used to investigate the structural and behavioural properties of the samples. X-ray analysis confirms the amorphous nature of samples. FTIR spectra reveal the presence of TeO3, TeO4 and TeO6 vibrational modes. Addition of manganese ions to the samples produces the change of tellurium ions coordination, namely the conversion of TeO4 into TeO3 structural units up to x = 12.4 mol% MnO. UV-VIS spectroscopy data show the presence of Te=O bonds from [TeO3] structural units and of transitions characteristic of Mn2+ and Mn3+ ions. The EPR spectra of the xMnO(100-x)TeO2 glasses are due to the presence of Mn2+ ions and consist of two resonance absorptions, a weak one located at geff ≈ 4.3 and a strong one at geff ≈ 2.0. The nature of EPR absorption lines and the influence of manganese content on the evolution of EPR lines intensity and linewidth are discussed. The PL spectra are due to the presence of manganese and tellurium ions in the studied samples.

Starch-coated Fe3O4 magnetic nanoparticles were synthesized and tested as adsorbents for Optilan Blue dye removal from aqueous solutions. The four tested magnetite samples were prepared through an environmentally friendly synthetic route which uses water as solvent and biocompatible sodium bicarbonate as precipitating agent. In addition to the control sample, three of the Fe3O4 nanoparticle samples were synthesized using fruit waste extracts from avocado (Persea americana) and watermelon (Citrullus lanatus) as surfactants. The Box–Behnken design approach was applied in order to determine the optimum experimental conditions for dye removal from aqueous solutions, selecting as independent variables initial concentration of dye, pH, temperature and adsorbent dose. A significant removal of the dye was obtained with an initial concentration of 50 mg L−1 with 0.6 g L−1, pH 2, at 35 °C. Three adsorption isotherms viz: the Langmuir, Freundlich and Temkin models were used to analyze the adsorption data, and kinetic and thermodynamic studies were also conducted.

Two types of magnetite (Fe3O4) nanoparticles were investigated as adsorbents for the simultaneous removal of Pb(II), Cd(II), and As(III) metal ions from aqueous solution. Magnetite nanoparticles were prepared by two synthesis procedures, both using water as solvent, and are referred to as conventional Fe3O4 nanoparticles and green Fe3O4 nanoparticles. The latter used Citrus limon (lemon) aqueous peel extract as the surfactant. Box–Behnken experimental design was used to investigate the effects of parameters such as initial concentration (20–150 mg L−1), pH (2–9), and biomass dosage (1–5 g L−1) on the removal of Pb(II), Cd(II), and As(III) ions. The optimum parameters for removal of the studied metal ions from aqueous solutions, including the initial ion concentration (20 mg L−1), pH (5.5) and adsorbent dose (5 g L−1), were determined. The pseudosecond-order model exhibited the best fit for the kinetic studies, while adsorption equilibrium isotherms were best described by Langmuir and Freundlich mo...

Plasticized poly(lactic acid) (PLA) samples with embedded Cu-doped ZnO powder functionalized with Ag nanoparticles composites were prepared by melt blending processing technique. The effect of ZnO:Cu/Ag nanoparticles on the properties of plasticized PLA was investigated in terms of structural (by Attenuated total reflectance – Fourier Transform Infrared – ATR-FT-IR, X–Ray Diffraction analysis – XRD) and morphological (using Scanning Electron Microscopy – SEM and Transmission Electron Microscopy – TEM examination) modifications, thermal (Differential Scanning Calorimetry – DSC), mechanical (transmittance, tensile strength), barrier antimicrobial properties and also in respect to migration of Cu, Zn an Ag nanoparticles into food simulants. It was found that the increase of nanoparticle content (from 0.5 to 1.5 wt%) of PLA formulations leads to the increase of the degree of crystallinity of PLA. The overall migration of all samples into three food simulants was below 10 mg·dm–2, accepted value according to EU Regulation No 10/2011 for plastic materials and articles intended to come into contact with food. Based on the obtained results it can conclude that the optimum composition is PLA/ZnO:Cu/Ag 0.5, this bionanocomposite offering suitable mechanical and thermal properties, good barrier properties to ultraviolet light, water vapour, oxygen and carbon dioxide, antibacterial activity and low migration amount of nanoparticles into food simulants.

Reduced graphene oxide (rGO) decorated with Fe doped SnO 2 nanoparticles were fabricated via the electrostatic interaction between positively charged modified Fe-doped SnO 2 oxide and negatively charged graphene oxide (GO) in the presence of poly(allylamine) hydrochloride (PAH). The decoration of rGO layers with SnO 2 :Fe nanoparticles was highlited by TEM microsopy. For composite sample the diffraction patterns coincide well with those of SnO 2 :Fe nanoparticles. The reduction of graphene oxide was evidenced using XRD and FT-IR spectroscopy. The formation of SnO 2 :Fe-PAH-graphene composites was confirmed by FT-IR, Raman and EPR spectroscopy. Sensitivity tests for relative humidity (RH) measurements were carried out at five different concentrations of humid air at room temperature. The prepared composite sensor exhibited a higher sensing response as compared with Fe:SnO 2 nanoparticles.

The present work highlights on efficacy of three types of green synthesized magnetite nanoparticles (Fe3O4 NPs) for the removal of a mixture of seven antibiotics, namely piperacillin (PIP), tazobactam (TAZ), sulfamethoxazole (SUL), tetracycline (TET), trimethoprim (TRI), ampicillin (AMP) and erythromycin (ERY) from aqueous media. Fe3O4 NPs were prepared through an environmentally friendly, facile and economical synthetic route which uses aqueous peel extracts of lemon (Citrus limon), black grapes (Vitis vinifera) and cucumber (Cucumis sativus), and were denoted as Fe3O4(lem), Fe3O4(grp) and Fe3O4(cum), respectively. The magnetic nanoparticles were characterized by XRD, FTIR, SEM, TEM, BET, XPS, and VSM techniques. A Box-Behnken design approach was employed in order to identify the optimum conditions for removal of selected antibiotics. The concentration of antibiotics was determined using high-performance liquid chromatography coupled with diode array detector and mass spectrometer (HPLC-DAD–MS) analysis. The Langmuir, Freundlich and Temkin adsorption isotherm models were used for description of the adsorption equilibrium of studied antibiotics and kinetic studies were conducted. Overall, Fe3O4 NPs synthesized with extracts exhibited high removal (>90%) of studied antibiotics, excepting SUL and TRI, and likewise demonstrated higher efficiency for the purpose of antibiotics removal than Fe3O4 NPs synthesized by a previously reported conventional method.

In this data article, we present supplementary data related to the research article entitled “Starch-coated green synthesized magnetite nanoparticles for removal of textile dye Optilan Blue from aqueous media” Stan et al., 2019. Data interpretations are included in the related research article Stan et al., 2019. The synthesized starch-coated Fe3O4 nanoparticles (ST-coated Fe3O4 NPs) were analyzed by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) to illustrate the shape and surface coating of nanoparticles. Moreover, the Brunauer-Emmett-Teller (BET) technique was used to evidence starch deposition on magnetite nanoparticles. The obtained nanocomposites were used for adsorption of Optilan Blue (OB) in batch conditions and the optimum agitation speed and point of zero charge (pHpzc) were established. After OB adsorption on ST-coated Fe3O4 NPs, the nanocomposites were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The stability of starch coated Fe3O4 NPs in the acidic as well as alkaline pH was also evidenced by FTIR spectroscopy. In addition, to test the stability of ST-coated Fe3O4 NPs, leaching experiments were carried out. The experimental data were compared with isotherm and kinetic models in order to determine the most suitable for fitting.

Photocatalytic degradation of organic pollutants has been established as one of the most effective and affordable technique to solve the environmental contamination issues. The present work was focused on the development of Cu doped ZnO-MWCNT nanocomposites designated for photodegradation of three water organic pollutants namely rhodamine (RhB) dye, phenol and oxytetracycline (OTC) antibiotic. The nanocomposite samples, with MWCNTs: ZnOCu weight ratios of 1:1, 1:3 and 1:5 were prepared and characterized using modern techniques. XRD revealed the presence of both MWCNT and ZnO crystalline phases in composites. The specific bands of MWCNT and ZnO composite components were highlighted by FT-IR. EPR and XPS spectroscopy showed the presence of Cu2+ ions inside the ZnO lattice. SEM and TEM images provided evidence of the attaching and distribution along the nanotubes of Cu doped ZnO nanoparticles with spherical form and diameter around 20 nm. The energy band gap of nanocomposites decreased with the increase of MWCNT amount. The PL emissions gradually quenched by increasing MWCNT content due to electron-hole recombination delays, which favors photocatalytic activity. Evaluation of nanocomposites as photocatalysts for degradation of the three types of pollutant solutions under visible irradiation demonstrated that all samples possessed photocatalytic activity. The best photocatalytic performance was acquired using MWCNT-ZnOCu-3 sample with degradation rates of 76%, 55% and 91% for RhB, OTC and phenol solutions, respectively. The mechanism of photocatalytic activity was elucidated based on the scavenger experiments, reactive oxygen species involved in this process and in correlation with energy bands alignment and gap states. The degree of mineralization of pollutant solutions obtained via total organic carbon analysis was evaluated.

In order to limit the photogenerated charges recombination and to ensure an efficient photocatalytic degradation of RhB pollutant, a MWCNT-ZnO:Fe composite material was designed. Fe doped ZnO Nps grouped into quasi-spherical structures of about 100–250 nm were grown in situ on MWCNTs using sol-gel method. The XPS and UPS analysis allowed the identification of both Fe2+ and Fe3+ ionic species at substitutional and surface positions. The substitutional Fe3+ will generate an inverse Burstein-Moss effect and, as a result, the Fermi level is will be pushed down towards the valence band by 0.7, 0.45 and 0.29 eV for 2, 3 and 5% Fe doping respectively. The Fe doped samples show ferromagnetic behavior as determined from both ESR and magnetization measurements. The ferromagnetic order, the inverse Burstein-Moss effect, and the hole capture into the MWCNT valence band favors the charge separation of photogenerated e-h pairs and the reactive oxygen species (ROS) generation in ZnO. The proposed energy bands setup allowed to elucidate both ferromagnetic order formation and the photodegradation mechanism. Thus, an Fe doping degree of 5% ensured, besides the highest magnetization, a 97% photodegradation efficiency and a pollutant mineralization degree of 92%.

Nowadays, the use of mobile telephony and wire-less devices has become more demanding, generating electromagnetic radiations. Microwave radiation can affect the growth rate of plants. For this study, the aromatic plants i.e. parsley, celery, dill, basil, were chosen as irradiated plants. This study aims to investigate the effects of irradiation with microwave field on polyphenolic compounds from basil, celery and parsley. The extracts were obtained by sonication. Quantitative analysis of polyphenolic compounds was performed by high performance liquid chromatography using an Altima C18 column. The elution was performed in gradient, with acetonitrile (eluent A) and formic acid in water (1%, eluent B). It was observed that in the irradiated plants, the content of polyphenolic compounds was higher than in the controlled plant. This finding suggests that that plants were strongly influenced by stress due to electromagnetic fields.

ZnO nanoparticles (ZnO NPs) were synthesized by chemical method (coprecipitation) and biological method using aqueous extracts of garlic (Allium sativum), rosemary (Rosmarinus officinalis) and basil (Ocimum basilicum). The influence of plant extract on the antibacterial and antioxidant activities of green synthesized nanoparticles was investigated. The X-ray diffraction studies reveal that all ZnO samples have hexagonal wurtzite structure. The particle size of ZnO NPs estimated by transmission electron microscopy analysis (between 14 and 27 nm) varies depending on the synthesis method of nanoparticles and the type of extracts from the plants used. The functional groups involved in the biosynthetic procedure were evidenced by Fourier transform infrared spectroscopy. The presence of Mn2+ ions, Zn vacancy complexes and oxygen vacancies in ZnO samples was highlighted by electron paramagnetic resonance spectroscopy. The green synthesized ZnO NPs have shown a good bactericidal activity against Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa bacterial strains. ZnO NPs synthesized using extracts of the selected plant species have been found to exhibit more enhanced antibacterial and antioxidant activities as compared to chemical ZnO NPs.

ZnO nanoparticles were successfully prepared by biological synthesis using aqueous extracts of Allium sativum (garlic), Allium cepa (onion) and Petroselinum crispum (parsley). For all ZnO samples, the XRD studies reveal a hexagonal wurtzite structure, without supplementary diffraction lines. The particle size is influenced by the type of plant extract used and varies between 14 and 70 nm. The biomolecules involved in the biosynthetic procedure was evidenced by FTIR spectroscopy. The presence of Mn and Fe in ZnO powders synthesized by using plant extracts was highlighted by ICP-MS. The EPR spectroscopy confirms the presence of Fe3+ and Mn2+ ions in ZnO samples and its variation depending on the plant extract. Also, Zn vacancy complexes and oxygen vacancies are present in all analyzed samples. A narrowing of the band gap for the ZnO prepared with plant extracts was observed as compared to that of the ZnO, prepared using solely ultrapure water. The photodegradation studies conducted in the presence of UV light irradiation indicated that ZnO nanoparticles prepared using garlic extract exhibit the highest efficiency in the photodegradation of methylene blue dye.

The goal of this study was to develop and validate a high-performance liquid chromatography method for the quantification of two essential oil constituents (myristicin and linalool) from extracts of the three aromatic plants exposed to low-intensity microwave radiation. The analysis was performed by high-performance liquid chromatography using a mobile phase consisting of ultrapure water and acetonitrile. The separations were carried out in the following conditions: isocratic conditions for 30 minutes with 100% acetonitrile and then linear gradient conditions from 100% acetonitrile to 25% acetonitrile for 15 minutes. The developed method was validated in terms of linearity, limits of detection, limits of quantification, precision, accuracy, and robustness. The results show that plants react differently under microwave stress and change their essential oil content as a response.

This paper reports the influence of doping degree and annealing temperature on XRD, Raman, EPR and PL spectra of Sn1−xVxO2 nanoparticles with x = 0, 0.01 and 0.05 annealed at 600 and 800 °C. XRD studies reveal a tetragonal rutile crystalline phases of tin oxide, while the formation of V2O5 secondary phase was evidenced for all doped nanoparticles only by Raman scattering. In function of the doping degree and annealing temperature, from EPR spectroscopy was evidenced the presence of three different positions for V4+ ions in the samples: isolated ions disposed on the nanoparticles surface, ions which are coupled by dipolar or exchange interactions and cluster ions. The luminescence emissions associated with oxygen vacancies and structural defects are influenced by doping degree and annealing temperature and could be correlated with the crystallite size determined from XRD patterns.

The aim of the present work was to establish a proper high-performance thin-layer chromatographic (HPTLC) method for the quantification of linalool and myristicin from leaf extracts of parsley, dill, and celery grown in microwave fields. In order to establish the influence of stress induced by microwave irradiation on plants, the plants selected for the study were subjected to irradiation with microwaves within two microwave frequency domains: GSM (mobile communication) and WLAN (wireless internet connection). The HPTLC analyses were performed in a normal chromatographic chamber on silica gel 60 plates, using petroleum ether—dichloromethane (30:70, v/v) as mobile phase. Photodensitometric evaluation of the chromatographic plates was carried out at 600 nm after spraying with vanillin reagent. The developed method was validated in terms of selectivity, linearity, limits of detection and quantification, precision, and accuracy.

A series of Sn0.99V0.01O2 powders were prepared and annealed at different temperatures: 450 C, 600 C, 800 C, 1000 C. The XRD measurements confirm the substitution of Sn 4+ ions by vanadium ions. A secondary phase of V2O5 was evidenced by Raman spectroscopy only in the samples annealed at 800 and 1000 C. The FTIR spectroscopy reveals the presence of oxygen vacancies. By XPS spectroscopy was evidenced the presence of four valence states for vanadium ions. The relative concentrations of these ions are influenced by annealing temperature. The EPR spectra for the samples annealed at 450 C and 600 C show a well resolved hyperfine structure composed of two sets of eight lines which is typical of the unpaired 3d 1 electron of 51 V (I = 7/2) in an axially distorted crystal field. At higher annealing temperature a superhyperfine structure due to the interaction with tin nuclei was observed. A ferromagnetic behaviour, probably due to the oxygen vacancies, was evidenced for the samples annealed at 450 C and 600 C.

Summary A high-performance thin-layer chromatography (HPTLC) method has been established for the analysis of α-phellandrene and β-pinene from dill (Anethum graveolens L.) extracts obtained by different extraction techniques and with different solvents and solvent mixtures. The HPTLC analyses were performed in a normal chromatographic chamber on silica gel 60 plates, using petroleum ether– dichloromethane (30:70, v/v) as mobile phase. Photodensitometric evaluation of the chromatographic plates was performed at 600 nm after spraying with vanillin reagent. It was also established that the α-phellandrene and β-pinene extractions depend on the extraction technique and extraction solvent. Taking into account the brief time of extraction and the maximum quantities of α-phellandrene and βpinene extracted, the most effective method was ultrasound-assisted extraction with n-hexane–diethyl ether (1:1, v/v). Studies of selectivity, linearity, limits of detection and quantification, precision, and accuracy were performed for method validation. The obtained results were compared and correlated with extraction method.

This article reports the effects of the annealing temperature on the structural, morphological and spin dynamic properties of SnO 2 samples doped with 0.005 Mn. The samples were annealed at 400, 600, 700 and 800 °C and analyzed by XRD, TEM, XPS and EPR spectroscopy. The XRD spectra show that the average crystallite size increases with the increase of the annealing temperature. The particles size and morphology were characterized by TEM microscopy. The valence bands of Mn were investigated by measuring the XPS spectra of Mn 2p core-level doublet. Regardless of the annealing temperature, the observed EPR spectra are due to (i) Mn 2+ ions either interstitially situated on the particle surfaces or isolated ones located substitutionally at Sn sites and (ii) Mn 4+ ions which substitute for Sn 4+ in SnO 2 lattice. The effects of the annealing temperature on the relative fractions of Mn 2+ and Mn 4+ ions are presented and discussed. In Sn 1− x Mn x O 2 ( x = 0.005) sample annealed at 400 °C, a FMR line was identified and attributed to a ferromagnetic phase.

Ferromagnetic resonance (FMR) investigations of nanocrystalline Zn1−xFexO (x = 0.01, 0.03 and 0.05) powders are reported. Broad FMR signals with g factor >2 representing the signature of ferromagnetism were identified. In the temperature range of 110–300 K, the magnetic field position of the resonance line shifts to lower fields and the shift increases with increasing x. The observed shift was attributed to an internal field arising from the spin sublattice within the host. The FMR line widths increase with the temperature decrease and increase with the increase in the Fe content x. This broadening is due to the presence of the non-homogeneous local magnetic fields in the investigated samples. A deviation of the experimental line shapes from the Lorentzian shape was identified in the low-temperature range.

Electron paramagnetic resonance (EPR) data on manganese-substituted tin dioxide (Mn:SnO2) samples are presented. The investigations show that the observed EPR spectra arise from three different contributions of Mn ions viz., (1) interstitial Mn2+ ions situated on the particle surfaces (2) isolated Mn2+ ions located substitutionally at Sn sites and (3) the Mn4+ ions which substitute for Sn4+ ions in SnO2 lattice. The effect of the dopant concentration on EPR spectra is also presented and discussed.

Electron magnetic resonance (EMR) investigations of Sn1− x Fe x O2 (x = 0.07) powders annealed at different temperatures are reported. EMR spectra show the presence of both the isolated paramagnetic Fe3+ ions incorporated into the SnO2 lattice and a ferromagnetically ordered component. By increasing the annealing temperature, the EMR spectrum attributed to the ferromagnetically coupled Fe3+ ions diminishes probably due to the migration of Fe ions and the formation of the second phase. The presence of the second phase was evidenced by X-ray diffraction measurements.

This is a report of an X-band electronic paramagnetic resonance (EPR) study of Zn1−x Co x O (x = 1 and 3%) powders at various temperatures (10–200 K). EPR spectroscopy is a powerful tool to study the complex magnetic state and the Co ionic state, their local environment and interactions as well. These samples are interesting to study in order to understand how ‘Co doping’ produces ferromagnetism in ZnO2, making it a promising ferromagnetic semiconductor at room temperature.

In this study, we report structural properties of the iron–tellurite glasses obtained using the sol–gel synthesis. The samples were characterized by X-ray diffraction, FTIR, UV–vis and EPR spectroscopy. Our results indicate dominant presence of iron ions in the trivalent state and the existence some Fe 2+ ions. The analysis of the IR spectra indicates a gradual transformation of iron ions from tetrahedral into octahedral sites when the concentration of Fe(NO 3 ) 3 is increased beyond 0.64 mol%. EPR studies show that the increase of Fe(NO 3 ) 3 content in the host matrix induces the growth of the number of effective g values. This can be explained considering that the orbitals of O 2− ion with a large spin–orbit interaction constant will interact with the 3d orbital of Fe 3+ ion bonded to this O 2− ion, thus leading to appearance of an orbital angular momentum which contributes to the magnetic moment of Fe 3+ ion. A strong dipolar interaction, which is more predominant in a glass with higher content of Fe(NO 3 ) 3 , causing a localized magnetic field along the site of the Fe 3+ ions and the increase the effective g values.

This paper reports the influence of Fe doping degree (1%, 3%, 5%) on structural and optical characteristics of gallium oxide nanoparticles evidenced by XRD, Raman, UV-vis and EPR methods. XRD studies reveal a monoclinic β-Ga2O3 structure. The lattice expansion sustains the substitutional incorporation of Fe ions in Ga2O3 host. The presence of a αFe2O3 secondary phase was evidenced for the samples doped with 3 and 5 % Fe only by Raman scattering. From UV-Vis absorption and EPR spectroscopy was evidenced the presence of isolated Fe3+ ions in octahedral sites, Fe2O3 particles, Fex3+Oy and oligomeric clusters.

In the present work we report the experimental results obtained on Ga2O3 nanoparticles doped with Cr ions. X-ray diffraction analysis confirms the substitution of Ga ions with Cr ions. A secondary phase of Cr2O5 oxides was evidence at high doping Cr concentration by Raman spectroscopy. Different valence state of Cr ions was highlighted by UV-VIS spectroscopy. EPR spectroscopy data show the presence of different environments for Cr ions, depending on the Cr addition.

The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn2+ ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs.

Influence of environmental stress factors on both crop and wild plants of nutritional value is an important research topic. The past research has focused on rising temperatures, drought, soil salinity and toxicity, but the potential effects of increased environmental contamination by human-generated electromagnetic radiation on plants have little been studied. Here we studied the influence of microwave irradiation at bands corresponding to wireless router (WLAN) and mobile devices (GSM) on leaf anatomy, essential oil content and volatile emissions in Petroselinum crispum, Apium graveolens and Anethum graveolens. Microwave irradiation resulted in thinner cell walls, smaller chloroplasts and mitochondria, and enhanced emissions of volatile compounds, in particular, monoterpenes and green leaf volatiles (GLV). These effects were stronger for WLAN-frequency microwaves. Essential oil content was enhanced by GSM-frequency microwaves, but the effect of WLAN-frequency microwaves was inhibitory. There was a direct relationship between microwave-induced structural and chemical modifications of the three plant species studied. These data collectively demonstrate that human-generated microwave pollution can potentially constitute a stress to the plants.

Mn-doped ZnO particles (x = 0.01 and 0.03) have been successfully prepared and sintered at 600 °C in air and argon atmosphere, respectively. The effects of annealing atmosphere on the structural, morphological and magnetic properties of obtained samples were studied. XRD studies reveal a wurzite-type structure for the samples with x = 0.01, while the formation of the secondary phases were evidenced for x = 0.03 samples. The samples annealed in Ar have much better crystallization. All EPR spectra present a hyperfine structure specific to isolated Mn2+ ions and for the sample x = 0.03 annealed in air, a new resonance line arises, which could be attributed to a ferromagnetic phase.

This paper reports the influence of the annealing in air and argon atmosphere on the structural and magnetic characteristics of Co-doped ZnO powders. XRD studies reveal a wurzite- type structure, while the formation of Co3O4 secondary phase was evidenced by Raman spectroscopy only for the sample annealed in air. A ferromagnetic behavior was observed for the sample annealed in air atmosphere and this behavior was explained. The sample annealed in argon atmosphere presents a paramagnetic behavior.

ZnO is an attractive system for a wide variety of practical applications, being a chemically stable oxide semiconductor. It has been shown that Fe doping produces ferromagnetic semiconductor at room temperature. This material, therefore, has the potential for use in spintronic devices such as spin transistors, spin light emitting diodes, very high density nonvolatile semiconductor memory and optical emitters. It is believed that oxygen vacancies and substitutional incorporation are important to produce ferromagnetism in semiconductor oxide doped with transition metal ions. The present paper reports detailed electron paramagnetic resonance investigations (EPR) of the samples in order to investigate how annealing atmosphere (Air and Argon) influenced the magnetic behavior of the samples. X-band electron paramagnetic resonance (EPR) studies of Fe3+ ions in Zn1−xFexO powders with x = 1%, 3% is reported. These samples are interesting to investigate as Fe doping produce ferromagnetism in ZnO, making a promising...

An X-band electron paramagnetic resonance (EPR) investigation of Fe3+ ions in Sn1-xFexO2 nanopowders with x = 0.005?0.07 is reported. These samples are interesting to investigate as Fe doping produce ferromagnetism in SnO2, making it a promising ferromagnetic semiconductor at room temperature.