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Porous silicon layers with different porosities were prepared by adjusting the anodization current density of the electrochemical etching process, starting from highly doped p-type crystalline silicon wafers. The microstructural parameters of the porous layers were assessed by high-resolution X-ray diffraction, total external reflection, scanning electron microscopy and nitrogen adsorption–desorption analysis. Furthermore, both the surface porosity and the mean porosity for the entire volume of the samples were estimated by employing total external reflection measurements and X-ray reciprocal-space mapping, respectively. The results clearly indicate that the surface porosity is different from the mean porosity, and the presence of a depth porosity gradient is suggested. To evaluate the porosity gradient in a nondestructive way, a new laboratory method using the grazing-incidence X-ray diffraction technique is reported. It is based on the analysis of the X-ray scattering profiles of the porous layers to obtain the static Debye–Waller factors. In this way, a description of the porosity gradient in a quantitative framework becomes possible, and, as a result, it was shown that the porosity increases exponentially with the X-ray penetration depth. Moreover, a strong dependence between the porosity gradient and the anodization current was demonstrated. Thus, in the case of the lowest anodization current (e.g.50 mA cm−2) a variation of only 15% of the porosity from the surface to the interface is found, but when applying a high anodization current of 110 mA cm−2the porosity close to the bulk interface is almost three times higher than at the surface.

This paper introduces for the first time the preparation of cobalt aluminate (CoAl2O4) nanoparticles through a solution combustion method using a Mentha piperita leaves extract. The active constituents present in the mentha leaves extract act as both a chelating and a reducing agent. The isolated precursor was characterized by FTIR, UV–Vis, thermal analysis and XPS. Various techniques (XRD, SEM and TEM, XPS, FTIR and UV–Vis) were also used to characterize the cobalt aluminate spinel from the point of view of structure, morphology and surface chemistry. XRD confirmed the formation of a single-phase, crystalline cubic spinel structure with mean crystalline domain size of 19.5 nm. The TEM analysis showed rhombic and rectangular CoAl2O4 nanoparticles with unimodal particle size distribution and average particle size of about 35 nm. The characteristic peaks of the CoAl2O4 spinel were highlighted by the FTIR spectrum. The tetrahedral configuration of Co2+ ions in the CoAl2O4 spinel structure was illustrated by the absorbance and XPS spectra. Furthermore, XPS spectra reveal both tetrahedral and octahedral configurations of Al3+ ions. To evaluate the catalytic properties of the cobalt aluminate, the photocatalytic degradation of methylene blue (MB) was carried out under visible light irradiation.

Resveratrol (RES) is a naturally occurring product with numerous biological activities. Despite its potential benefits, its use is limited due to its low aqueous stability and solubility in its native form. The porous sol–gel silica materials which are able to entrap different organic molecules represent new studied release carriers. The aim of this work was to generate a solid matrix to encapsulate RES ensuring protection, increased solubility and release in solutions. A non-toxic ingredient, namely β-cyclodextrin (β-CD), able to form inclusion complexes (ICs) with RES has been used. Ecological formulations have been processed by entrapping the RES containing ICs in silica matrices obtained from a silica colloidal sol by the aqueous route of the sol–gel method. Characterization methods (DSC, FTIR, UV–Vis, fluorescence studies, SEM) have evidenced the presence of RES–β-CD inclusion complex in the silica powder, RES stability in the matrix and its release in aqueous and organic solutions, and the morphology of the carrier. An evaluation of the antioxidant activity of RES in the present formulation was performed by the chemiluminescence assay and RES release profile in aqueous solutions was obtained by HPLC–MS. The resulted materials can find applications in different domains.

New bimetallic LnTi-SBA-15 (where Ln is Eu or Pr) photocatalysts were obtained by immobilization of the lanthanide ions on Ti-SBA-15 supports synthesized by direct- and post-synthesis methods. The obtained materials were characterized by X-ray diffraction, SEM microscopy, N2 adsorption-desorption and UV-Vis spectroscopy. The obtained results evidenced an insignificant effect of Eu and Pr on support ordered mesoporous structure and optical properties of titania dispersed species. The activity of these photocatalysts was evaluated in the photocatalytic degradation, under UV light (254 nm), of Brilliant blue FCF from aqueous solutions. A higher activity was obtained for samples with lower loading of lanthanide. The best results were obtained for samples with lowest Eu oxide loading (2.5%).

A red-emitting fluorescent Riboflavin (RF)/Polyvinylpyrrolidone (PVP)-coated silver nanoparticles system, λ

This paper describes for the first time two processing routes—the precursor method and the two-step wet chemical process—for the synthesis of magnetic cobalt ferrite using the Tamarindus indica fruit extract. These green approaches are eco-friendly, safe and efficient alternatives to classical chemical methods. The aqueous extract from tamarind fruit contains numerous metabolites (organic acids, aminoacids). All these bioactive components are able to chelate metal ions leading to the formation of the multimetallic complex (precursor of cobalt ferrite). The obtained precursor was characterized by Fourier transform infrared spectroscopy (FTIR), thermal analysis, X-ray diffraction analysis (XRD) and magnetic measurements. The structure, morphology and magnetic behavior of the cobalt ferrite samples prepared through both synthesis routes were investigated by various characterization techniques: FTIR, XRD, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), Mossbauer spectroscopy and magnetic measurements. XRD data confirmed that a cubic spinel structure was obtained for both ferrite powders with average crystallite size of 13 and 5 nm, respectively. The microstructure study by SEM revealed the formation of nanocrystallites assemblies using the precursor method and carbon-rich particles forming granulated micron-sized agglomerates, embedding ferrite nanocrystallites obtained through the two-step wet chemical process. Mossbauer spectroscopy results evidenced relaxation processes in the CoFe2O4 samples at room temperature, and the main characteristics of the involved sublattices were derived. The magnetic investigation revealed a typical magnetic behavior for a spinel, with CoFe2O4 nanoparticles ferrimagnetic at low temperature and superparamagnetic at room temperature.

Two novel fluorescent mesoporous silica-based hybrid materials were obtained through the covalent grafting of [4-hydrazinyl-7-nitrobenz-[2,1,3-d]-oxadiazole (NBDH) and N1-(7-nitrobenzo[c][1,2,5]-oxadiazol-4-yl) benzene-1,2-diamine (NBD-PD), respectively, inside the channels of mesoporous silica SBA-15. The presence of fluorescent organic compounds (nitrobenzofurazan derivatives) was confirmed by infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG), and fluorescence spectroscopy. The nitrogen physisorption analysis showed that the nitrobenzofurazan derivatives were distributed uniformly on the internal surface of SBA-15, the immobilization process having a negligible effect on the structure of the support. Their antioxidant activity was studied by measuring the ability to reduce free radicals DPPH (free radical scavenging activity), in order to formulate potential applications of the materials obtained. Cytotoxicity of the newly synthesized materials, SBA-NBDH and SBA-NBD-PD, was evaluated on human B16 melanoma cells. The morphology of these cells, internalization and localization of the investigated materials in melanoma and fibroblast cells were examined through fluorescence imaging. The viability of B16 (3D) spheroids after treatment with SBA-NBDH and SBA-NBD-PD was evaluated using MTS assay. The results showed that both materials induced a selective antiproliferative effect, reducing to various degrees the viability of melanoma cells. The observed effect was enhanced with increasing concentration. SBA-NBD-PD exhibited a higher antitumor effect compared to SBA-NBDH starting with a concentration of 125 µg/mL. In both cases, a significantly more pronounced antiproliferative effect on tumor cells compared to normal cells was observed. The viability of B16 spheroids dropped by 40% after treatment with SBA-NBDH and SBA-NBD-PD at 500 µg/mL concentration, indicating a clear cytotoxic effect of the tested compounds. These results suggest that both newly synthesized biomaterials could be promising antitumor agents for applications in cancer therapy.

Mining activities have a high negative impact on the environment and on human health. Environmental impacts can result in contamination of surface water, groundwater, soil and air. Large volumes of wastewater produced by mining activities have to be remediated before being discharged into the environment. Due to the complex composition of wastewater coming from the mining industry and because their negative impacts, numerous remediation techniques have been applied. Adsorption is one of the most extensively used ways to remediate mining wastewater as a consequence of its low cost, easiness to be performed, and also due to the wide variety of materials (natural and synthetic) that can be use as adsorbents. Hydroxyapatite (HAP, Ca10(PO4)6(OH)2), a naturally occurring form of calcium phosphate has a good capacity to remove heavy metal ions from aqueous solutions due to its excellent properties. By preparing hydroxyapatite using different synthesis methods, its properties can be manipulated in order to increase the adsorption properties and reactivity. Herein, we reported synthesis of hydroxyapatite (HAP) samples using different synthesis conditions to establish the effect of synthesis conditions onto HAP properties. The HAP samples prepared have been characterized by the use of X-ray diffraction, FT-IR spectroscopy, specific surface measurements, Scanning Electron Microscopy (SEM). The stoichiometric compounds with high degree of crystallinity, low average particle diameter values, and low specific surface have been prepared by the solid state reaction and high calcination temepratures. The addition of surfactant (dispersant) has resulted in an increase in the specific surface area, which will result in an increase in the retention capacity of heavy metal ions in wastewater. The adsorbents prepared were used to remediate mine water. Results showed that non-calcinated HAP samples have a higher heavy metals adsorption capacity compared to HAP samples calcinated at 600 �C and 900 �C. The HAP samples prepared in presence of surfactant exhibit a higher heavy metals adsorption capacity than samples prepared in absence of surfactant. The values of the retention capacity differ depending on the nature of the metal ion: QMn(II) ] QFe(III) ] QZn(II) ] QPb(II) ] QNi(II). A change in the pH of mine water from 2.6 to 5.5 has occur that means that the metal ion retention mechanism goes through chemical reactions. The metal ions retention capacity suggests application of hydroxyapatite for remediation of mining wastewater.

The nanostructured cobalt aluminate (CoAl2O4) was obtained through an eco-friendly precursor method using aqueous extract of tamarind fruit. The use of plant extracts is a simple and effective approach for the preparation of CoAl2O4 nanoparticles. The polynuclear complex precursor was characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–VIS) and thermal analysis. The cobalt aluminate was investigated by: X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR, UV–VIS and colour measurements by reflectance spectroscopy (RS). X-ray diffraction patterns confirmed the formation of cubic CoAl2O4 spinel phase with good crystallinity. The average particle size from TEM is about 71 nm. Chromatic coordinates indicate that the bluest colour was obtained for the cobalt aluminate obtained by subsequent heat treatment.

Mesoporous silica nanoparticles (MSNs) coated with biopolymers are already known for their enormous benefits, as a pharmaceutical matrix, in the medical and pharmaceutical fields. Here, we report the preparation of two types of hybrid matrices, containing SBA-15-MSNs covered with mucilaginous polysaccharides extracted from Althaea officinalis folium in natural and acid pH conditions and polyphenols fraction from Betonica officinalis, respectively. The analysis of phenol composition reveals a selective polysaccharides fraction immobilized on SBA-15-MSNs and evidences higher concentration of polyphenols in Althaeae extract obtained in natural conditions. The acid pH of the extraction conditions favored immobilization of polyphenols on the surface of silica support compared to those obtained under natural conditions. The results regarding the two plant extracts cytotoxicity against the tumour cell line Hep-2 suggest that if Althaeae folium extract is able to reduce the viability of Hep-2 cancer cells likely by reducing the accessibility of the tumour cells to nutrients from the medium, Betonica officinalis extract has the capacity to reduce Hep-2 tumour cell viability by interfering with inner metabolism of the cell. Given these, new effective antiproliferative material biocomposites are expected when combining Althaeae and Betonica extracts.

In this work, we present a simple, two-stage method for the preparation of new and efficient antimicrobial hybrid systems, based on isoniazid and pyrazine-2-carbohydrazide tuberculostatic agents covalently linked to graphene oxide. In the first step, the carboxyl groups of graphene oxide are activated by transforming them into the corresponding acid chloride groups, which, in the second step, will react with the amino groups of the two drugs. Pyrazine-2-carbohydrazide was obtained from pyrazinoic acid and hydrazine hydrate and was confirmed by nuclear magnetic resonance spectroscopy. The materials have been characterized by elemental analysis, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Their antimicrobial activity was tested on mycobacterial (Mycobacterium terrae), as well as on Gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), Gram-positive bacteria (Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 25923) and fungal (Candida albicans ATCC 10231), in planktonic and biofilm growth state. The biocompatibility of the tested compounds was assessed in vitro by live-dead fluorescence staining and flow cytometry. The results of this study have shown that the functionalization of graphene oxide with isoniazid and pyrazine-2-carbohydrazide both enhanced the anti-mycobacterial activity of the respective drugs and extended their antimicrobial spectrum towards other microbial strains, in planktonic and biofilm growth state, showing a promising potential for mitigating the impact of antimicrobial resistance and the deleterious effects of microbial biofilms. At the active tuberculostatic concentrations, the tested compounds exhibit very low cytotoxicity and do not interfere with the cellular cycle of Hep-2 cells. The flow cytometry and live/dead fluorescence staining proved that the tested compounds exhibit a microbicidal effect through induction of cellular lesions, consecutive to membrane depolarization.

Bone defects due to trauma or diseases causing bone loss have led to an increased demand for new materials that have applications in therapies for bone pathologies. Mesoporous bioactive glasses (MBGs), based on 70SiO2-(26-x)CaO 4P2O5-xCeO2 (x = 0, 1 and 5 mol % for MBGS, MBGS1Ce and MBGS5Ce) were synthesized by evaporation-induced self-assembly (EISA) method. Ceria was selected due to its antimicrobial and antioxidant properties and positive impact on cells differentiation and mineralization. The pore size values of 2.8 nm confirmed the mesoporosity of the obtained bio-glasses. The biocompatibility tests on mouse fibroblast cells (NCTC clone L929) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) activity assays revealed no cytotoxicity of Cerium containing MBGs. Formation of a hydroxycarbonate apatite (HCA) layer on MBGs surface, e.g. bioactivity of BMGs, was confirmed by XRD, FTIR, SEM and Raman Spectroscopy while presence of Ce3+/Ce4+ in the glasses before body simulated fluid (SBF) immersion was determined by XPS, UV–Vis measurements. The obtained results show that investigated MBGs are potential materials for applications in bone regeneration.

Goethite based nanocomposites with a different composition such as 6FeO(OH)·MnO(OH)·0.5H2O (Mn-composite), xFeO(OH)·M(OH)2·yH2O (Co-composite (M: Co, x = 12, y = 3), Ni-composite (M: Ni, x = 7, y = 2)) and xFeO(OH)·MO·yH2O (Cu-composite (M: Cu, x = 5.5, y = 3), Zn-composite (M: Zn, x = 6, y = 1.5)) have been prepared by a soft chemical synthesis consisting in acetate hydrolysis. The data provided by Fourier transform infrared (FTIR), ultraviolet-visible-near infrared (UV-Vis-NIR), electron paramagnetic resonance (EPR) and Mossbauer spectra account for a slight modification of all composites' physicochemical properties compared to the starting material. Powder X-ray diffraction and transmission electron microscopy (TEM) investigations revealed the secondary phase nature and presence along with that of goethite. The TEM data are also consistent with a nano rod-like morphology with a 5–10 nm width and an average length of 40 nm. The catalytic oxidation of cyclooctene with O2 using isobutyraldehyde as reductant and acetonitrile as a solvent was performed in batch conditions for 5 h at room temperature. The selectivity for the epoxide was higher than 99% for all tested solids. The conversion of cyclooctene decreased from 55% to 4% following the same order of variance as the base/acid sites ratio: Mn-composite > Fe-composite > Co-composite > Ni-composite > Zn-composite > Cu-composite. The 6FeO(OH)·MnO(OH)·0.5H2O (Mn-composite) exhibited the most promising catalytic activity in cyclooctene oxidation, which can be correlated with the redox ability of Mn(III) combined with the increased base character of this solid. The catalytic activity of this sample decreases by 10% after several successive reaction cycles.

Three new complexes of Ni(II), Cu(II) and Zn(II) with deoxycholate anion, of the type M(DCA)2 · nH2O (M = Cu(II) n = 4, M = Ni(II) n = 3 and M = Zn(II) n = 2) have been synthesized and characterized on the basis of elemental analysis, FTIR and UV-Vis spectroscopy, thermal analysis, molar conductivity and magnetic measurements. The cytotoxicity of the synthesized complexes was tested against HT29 human colorectal cancer cells. Applied at a concentration range of 10 - 200 µg/mL, sodium deoxycholate and its metal complexes have been found to decrease viability and growth of cultured HT29 cells in a time- and concentration-dependent manner in short-term and long-term experiments. The ability of the complexes to induce pathological changes, genotoxicity and apoptosis in the treated cells has also been proved. In addition, the complexes demonstrated a cytotoxic effect in HT29-OxPt (resistant to oxaliplatin) cells, allowing to conclude that they are more pronounced cytotoxic agents as compared to the sodium deoxycholate alone.

Titanium dioxide, TiO2, plays an important role due to its catalytic properties and high chemical [...]

The present study concerns the in vitro oxidative stress responses of non-malignant murine cells exposed to surfactant-tailored ZnO nanoparticles (NPs) with distinct morphologies and different levels of manganese doping. Two series of Mn-doped ZnO NPs were obtained by coprecipitation synthesis method, in the presence of either polyvinylpyrrolidone (PVP) or sodium hexametaphosphate (SHMTP). The samples were investigated by powder X-ray Diffraction, Transmission Electron Microscopy, Fourier-Transform Infrared and Electron Paramagnetic Resonance spectroscopic methods, and N2 adsorption–desorption analysis. The observed surfactant-dependent effects concerned: i) particle size and morphology; ii) Mn-doping level; iii) specific surface area and porosity. The relationship between the surfactant dependent characteristics of the Mn-doped ZnO NPs and their in vitro toxicity was assessed by studying the cell viability, intracellular reactive oxygen species (ROS) generation, and DNA fragmentation in NIH3T3 fibroblast cells. The results indicated a positive correlation between the specific surface area and the magnitude of the induced toxicological effects and suggested that Mn-doping exerted a protective effect on cells by diminishing the pro-oxidative action associated with the increase in the specific BET area. The obtained results support the possibility to modulate the in vitro toxicity of ZnO nanomaterials by surfactant-controlled Mn-doping.

Graphene oxide has been functionalized with crown-ether moieties, while silica has been functionalized with stable free radicals of nitroxide type. These two materials and their mixture were firstly characterized by IR, ESR, SEM, and Raman spectroscopy, and secondly tested further for removal of some organic and inorganic pollutants from water, like benzyl alcohol, methylene blue dye, iron (II), and copper (II) ions. It is well known that graphene oxide, as well as crown-ether compounds, has a high capacity to bind transition metal ions, whereas nitroxide free radicals are able to oxidize, under certain conditions, organic compounds. Consequently, our experiments evaluated these materials and showed that they may act synergistically in order to simultaneously remove metal ions and organic pollutants.

Nitrogen (N)-doped SrTiO3 /pristine SrTiO3 powders were synthesized by three different methods namely hydrothermal, sol-gel route and solid state reaction respectively. The influence of synthesis route, thermal treatment atmosphere and N doping on the properties and photo-catalytic efficiency of the prepared samples was analyzed. The investigation shows that N doping causes the narrowing of the band gap with about 1 eV. The synergy of the structure, texture and morphology and especially N doping explains high methyl orange (MO) degradation efficiency of 100% within 1 h of irradiation for the N doped SrTiO3 obtained by sol-gel route with the aid of non-ionic triblock copolymer (Pluronic P123) as a structure-directing and thermally treated under nitrogen atmosphere.

Four complexes of Co(II), Ni(II), Cu(II), and Zn(II) with isoxicam (H2ISO) as ligand, namely [Co(HISO)2(H2O)2]⋅3H2O (Co–Iso), [Ni(HISO)2(H2O)2]⋅0.5H2O (Ni–Iso), [Cu(HISO)2(H2O)] (Cu–Iso), [Zn(HISO)2(H2O)2]⋅0.5H2O (Zn–Iso), have been synthesized and characterized by FT-IR, UV–Vis–NIR, 1H NMR, TG/DSC, elemental analysis, magnetic and conductivity measurements. The following permanent cell lines were used to evaluate the cytotoxic activity of the compounds: LSCC-SF-Mc29, strain E7 (transplantable chicken hepatoma induced by the myelocytomatosis virus Mc29), LSR-SF-SR (transplantable sarcoma in rat, induced by Rous sarcoma virus, strain Schmidt-Ruppin), MCF-7 (luminal A type breast cancer), HeLa (human carcinoma of the uterine cervix) and Lep-3 (human non-tumor embryonal fibroblastoid cells). Short term experiments (24–72 h) with monolayer cultures were performed by MTT test, neutral red uptake cytotoxicity assay and double staining with acridine orange and propidium iodide as well as long term experiments (20 days) with 3D cancer cell colonies in semi-solid medium. The results obtained reveal that: (i) applied at a concentration range of 5–500 µg mL−1 the compounds investigated decrease in a time- and concentration-dependent manner viability and/or proliferation of the treated cells; (ii) metal complexes are more pronounced cytotoxic agents as compared to isoxicam; (iii) cell-specific response was observed—Cu–Iso expresses the highest cytotoxic activity in LSCC-SF-Mc29 (strain E7) cells, whereas Zn–Iso is the most effective compound in LSR-SF-SR and Lep-3 cells, and Co–Iso—in HeLa cells; (iv) in general, human non-tumor Lep-3 embryonic fibroblastoid cells are relatively less sensitive to the cytotoxic activity of the complexes as compared to human cancer MCF-7 and HeLa cells.

A series of three chitosan-based magnetic composites was prepared through a simple coprecipitation method. It was investigated the influence of mass ratio between chitosan and magnetite on the physical and chemical properties of the composites in order to establish the optimum conditions for obtaining a composite with good adsorption capacity for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions. It was found that the microspheres prepared using mass ratio chitosan / magnetite 1.25/1, having a saturation magnetization of 15 emu g--1, are the best to be used as adsorbent for the metal ions. The influence of different parameters such as initial pH values, contact time, initial concentration of metal ions, on the adsorption of Pb(II) and Cu(II) onto the chitosan-based magnetic adsorbent was investigated in details. The adsorption process fits the pseudo-second-order kinetic model in both mono and bicomponent systems, and the maximum adsorption capacities calculated on the basis of the Langmuir model were 79.4 mg g--1 for Pb(II) and 48.5 mg g--1 for Cu(II) in monocomponent systems, while in bicomponent systems were 88.3 and 49.5 mg g--1, respectively. The results revealed that the as prepared chitosan-based magnetic adsorbent can be an effective and promising adsorbent for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions.

The aim of this study consisted in developing an efficient strategy for performing a real emulsion ATRP process in the presence of a dual function unit that acts both as emulsifier and initiator. The particles morphology and size distribution were determined through SEM and DLS analyses. The average particle diameter was around 500–700 nm (DLS), which confirms the obtaining of an emulsion and not a miniemulsion. The polymerization mechanism involves a micellar nucleation stage. The gel permeation chromatography (GPC) analyses confirmed controlled molecular weights and low polydispersity indexes (PD) and the kinetics study showed linear relationship of ln([M0]/[M]) with the reaction time, indicating the “living/controlled’’ feature of the emulsion polymerizations. The “living” characteristic of the polymerization was demonstrated through the synthesis of a block-copolymer. This promising method has both an academic value and industrial feasibility in the research for soap-free ATRP emulsion polymerizations.

Chromium substituted cobalt ferrites CoFe2−xCrxO4 (x = 0; 1; 1.5) were synthesized through a soft chemistry method—the gluconate precursor route. The gluconate precursors were characterized by infrared spectroscopy (IR), ultraviolet–visible spectroscopy and thermal analysis. The spinel oxide powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mossbauer spectroscopy and Brunauer–Emmett–Teller N2 adsorption–desorption analyses. XRD indicated the formation of the spinel-type phase with good crystallinity. The mean crystalline domains size decreased from 23.8 to 17.8 nm with the increase in the chromium content. SEM revealed faceted particles for which the particle sizes varied significantly with the chromium content. The chromium substituted cobalt ferrites were found to have high catalytic performance.

The challenge for conformal modification of the ultra-high internal surface of nanoporous silicon was tackled by electrochemical polymerisation of 2,6-dihydroxynaphthalene using cyclic voltammetry or potentiometry and, notably, after the thermal treatment (800 °C, N2, 4 h) an assembly of interconnected networks of graphene strongly adhering to nanoporous silicon matrix resulted. Herein we demonstrate the achievement of an easy scalable technology for solid state supercapacitors on silicon, with excellent electrochemical properties. Accordingly, our symmetric supercapacitors (SSC) showed remarkable performance characteristics, comparable to many of the best high-power and/or high-energy carbon-based supercapacitors, their figures of merit matching under battery-like supercapacitor behaviour. Furthermore, the devices displayed high specific capacity values along with enhanced capacity retention even at ultra-high rates for voltage sweep, 5 V/s, or discharge current density, 100 A/g, respectively. The cycling stability tests performed at relatively high discharge current density of 10 A/g indicated good capacity retention, with a superior performance demonstrated for the electrodes obtained under cyclic voltammetry approach, which may be ascribed on the one hand to a better coverage of the porous silicon substrate and, on the other hand, to an improved resilience of the hybrid electrode to pore clogging.

The aim of this work was an investigation of structural and electrical properties of ZnO/Zn2-xFexTiO4 (x = 0.7, 1, 1.4) powders. The compounds obtained by sol-gel method are characterized by several techniques: X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), electrical and dielectrical measurements. The XRD, SEM and XPS analysis confirmed the formation of ZnFeTiO4 inverse spinel structure. The electrical and dielectrical properties of ZnO/Zn2-xFexTiO4 (x = 0.7, 1, 1.4) were measured by impedance spectroscopy, revealing a decrease in the electrical conductivity and the dielectric constant with Fe content.

Three Schiff base-functionalized mesoporous silicas: MCM-41@salen, HMS-C12@salen and HMS-C16@salen have been synthesized by a post-synthetic grafting strategy and their sorption capacities toward Pb(II) from synthetic aqueous solutions have been assessed. FTIR spectra, TG/DSC analyses, X-ray powder diffraction, X-ray photoelectron spectroscopy (XPS), N2 adsorption isotherms and HRTEM micrographs were used to characterize the novel functionalized mesoporous silicas. The novel adsorbents have been tested for their capability in the remediation of synthetic aqueous systems containing Pb(II). The Langmuir maximum values of sorption capacities of these adsorbents toward Pb(II) are: 138.88 mg Pb(II) per g MCM-41@salen, 144.92 mg Pb(II) per g HMS-C12@salen, and 181.81 mg Pb(II) per g HMS-C16@salen, therefore, the functionalized silicas (MCM-41@salen, HMS-C12@salen, HMS-C16@salen) could be used as effective adsorbents of Pb(II) ions from wastewater.

Un-doped and doped strontium aluminates (Sr 3 Al 2 O 6 , Sr 3 Al 2 O 6 :Tb 3+ , Sr 3 Al 2 O 6 :Tb 3+ ,Eu 3+ and Sr 3 Al 2 O 6 :Tb 3+ ,Eu 3+ /Eu 2+ ) were synthesized through a soft chemical method – the tartarate precursor route. The tartarate precursors were characterized by infrared spectroscopy (IR) and thermal analysis. The strontium aluminates were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR). The XRD patterns confirmed the formation of single-phase cubic structure Sr 3 Al 2 O 6 with average crystallite size of 18 nm. SEM micrographs showed porous polycrystalline powder microstructures and EDX analysis confirmed the incorporation of the dopant in the Sr 3 Al 2 O 6 powders. The photoluminescence spectrum recorded on Sr 3 Al 2 O 6 : Tb 3+ ,Eu 3+ (obtained from tartarate precursor calcined in air) showed the typical f-f luminescences of the RE-ions. Subsequent calcination of this sample in reducing atmosphere is accompanied by new photoluminescence and thermoluminescence features associated to the Eu 2+ ions.

The application of biopolymer-based sorbents in solving some environmental problems such as the removal and recovery of heavy metals from natural polluted water and wastewater has received lately a lot of attention due to their unique characteristics. The fundamental properties that recommend the usage of biopolymers-based sorbents for environmental remediation are: high selectivity and sorption capacity, renewability, safe manipulation, sorption capacity increase through simple physical and chemical methods, easy separation from treated water, and easy regeneration and reuse for repetitive sorption-desorption cycles. Accordingly, this research study has as purpose to present the results related to the usage of two types of alginate sorbents (calcium alginate and chitosan coated calcium alginate) in four repetitive lead(II) ions sorption-desorption cycles and to examine the influence of desorption agents on structural sorbent�s characteristics. The results obtained showed that both calcium alginate and chitosan coated calcium alginate are good stable sorbents to be used in lead(II) ions sorption-desorption cycles.

A novel nanocomposite was obtained through the covalent immobilization of lipoic acid on the surface of silver nanoparticles-decorated silica nanoparticles (SiO 2 @Ag). The hybrid organic – inorganic material obtained was characterized by Fourier transform infrared spectroscopy, thermal analysis, scanning and transmision electron microscopy, X-ray photoelectron spectroscopy and UV-Visible spectroscopy. Its antioxidant, cytotoxic, antimicrobial activity and influence on mammalian cells cycle were evaluated. The results of this study have shown that the functionalization of SiO 2 @Ag with lipoic acid resulted in a composite with increased specificity of interaction with different mammalian cell lines and antioxidant activity, but with decreased cytotoxicity and antimicrobial properties. Therefore, the SiO 2 @Ag functionalized with lipoic acid could be successfully used in certain concentrations to modulate the cell cycle, in order to obtain the desired anti-proliferative or stimulatory therapeutic effect.

In this paper, the CO oxidation on Pd/TiO 2 and Pd/SnO 2 /TiO 2 catalysts was studied using a non-conventional tool: AC electrical measurements in operando conditions. The structural and textural properties of the obtained powders have been characterized using BET, XRD, SEM, and CO chemisorption. Their redox properties were tested using the TPR technique. The surface dynamics was studied by electrical conductivity measurements under similar conditions with those encountered in the practical use in catalysis and correlated with their performances in CO oxidation.

The formation and growth of gold nanoparticles (AuNPs) were investigated in pH 7 buffer solution of bovine serum albumin (BSA) at room temperature. The processes were monitored by UV-Vis, circular dichroism, Raman and electron paramagnetic resonance (EPR) spectroscopies. TEM microscopy and dynamic light scattering (DLS) measurements were used to evidence changes in particle size during nanoparticle formation and growth. The formation of AuNPs at pH 7 in the absence of BSA was not observed, which proves that the albumin is involved in the first step of Au(III) reduction. Changes in the EPR spectral features of two spin probes, CAT16 and DIS3, with affinity for BSA and AuNPs, respectively, allowed us to monitor the particle growth and to demonstrate the protective role of BSA for AuNPs. The size of AuNPs formed in BSA solution increases slowly with time, resulting in nanoparticles of different morphologies, as revealed by TEM. Raman spectra of BSA indicate the interaction of albumin with AuNPs through sulfur-containing amino acid residues. This study shows that albumins act as both reducing agents and protective corona of AuNPs.

The Ti/hierarchical zeolites Y were obtained by direct and post synthesis methods and loaded with Fe(III) by ion-exchange and impregnation resulting Fe-Ti/hierarchical zeolites Y photocatalysts. The synthesized materials were characterized by XRD, SEM microscopy, N2 physical adsorption, Raman, UV-Vis and XPS and EPR spectroscopy. XRD patterns evidenced the crystalline structure of the zeolite Y in all materials, excepting the samples with higher Fe content. The presence of anatase was evidenced by XRD and Raman spectroscopy in the samples obtained by impregnation while α-Fe₂O₃ was depicted in the Raman spectra of the samples with Ti and lower Fe loading. SEM images and N2 adsorption-desorption isotherms confirmed the formation of mesopores together with microporous crystals of zeolite Y. The UV-Vis spectra proved a red-shifted adsorption band for samples with iron. In all these samples XPS shows Fe3+ as oxide on the surface and EPR Fe3+ in tetrahedral coordination. Different variables such as hierarchical structure, amount of iron, catalyst loading, concentration of pollutant solution, pH value were studied to estimate their effects on performances of photocatalysts in degradation of amoxicillin from aqueous solution in UV and Visible light. A higher adsorption capacity and degradation efficiency of amoxicillin (100%) was noticed for hierarchical materials, especially for higher iron oxide loaded samples.