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The aim of this study was the synthesis and structural characterization of SiO2–Al2O3 microspheres with SiO2 core and (100 − x)Al2O3·xFe2O3 (x = 0, 5, and 10 mol%) shell. Smooth spherical silica particles of uniform size around 1 μm have been synthesized as core material based on the Stober method. In order to enhance the specific surface area, the silica particles were coated with a thin nanostructurated shell, about 15 nm, of aluminum and iron oxides (100 − x)Al2O3·xFe2O3 (x = 0, 5, and 10 mol%). The embedding of iron oxide in the covering shell was related to potential applications of these composite biomaterials for contrast enhancement in magnetic resonance imaging (MRI) and at the same time for local treatments of cancer by hyperthermia. The XRD results point out the amorphous structure of the obtained core–shell particles. The TEM images evidence continuous shell coating of silica spherical microparticles and the XPS analysis of the surfaces prove the occurrence of iron oxide on the outermost layer of the microspheres. Both FTIR and XPS results evidence the formation of Al–O–Si linkage proving that Al2O3 and SiO2 are chemically bonded in the investigated core–shell microspheres.

The co-crystals formation of etravirine with three carboxylic acids was investigated. New co-crystals of etravirine with adipic acid, benzoic acid, and 4-hydroxybenzoic acid have been synthesized by wet milling of ingredients for 120 min. The novelty of these solid forms was first evidenced by powder X-ray diffraction. Their different morphology was evidenced by SEM microscopy. Spectroscopic analyses (FT-IR, MAS-NMR, and XPS) highlighted the hydrogen bonds between etravirine and co-formers, as a result of the solid-state reaction of the ingredients by wet milling. Thermal analyses pointed out that the milling process caused in co-crystals a reduction in the fusion enthalpy and the melting temperature, compared to the values obtained for etravirine. These co-crystals are stable up to four months on storage under extreme conditions, excepting the co-crystal with benzoic acid which begins to transform into a polymorph of etravirine after 30 days. The UV absorption spectra of the samples tested in three simulated physiological media with pH values of 6, 6.3, and 7 have evidenced the conformation change of etravirine due to hydrogen bonds between etravirine and carboxylic acids.

Bioactive glasses doped with silver are aimed to minimize the risk of microbial contamination; therefore, the influence of silver on the bioactive properties is intensely investigated. However, information related to the role played by silver, when added to the bioactive glass composition, on biocompatibility properties is scarce. This aspect is essential as long as the silver content can influence blood protein adsorption onto the surface of the glass, thus affecting the material's biocompatibility. Therefore, from the perspective of the biocompatibility standpoint, the finding of an optimal silver content in a bioactive glass is an extremely important issue. In this study, silver-doped bioactive glasses were prepared by a melt-derived technique, which eliminates the pores' influence in the protein adsorption process. The obtained glasses were characterized by X-ray diffraction, UV-vis, X-ray photoelectron (XPS) and Fourier transform infrared (FT-IR) spectroscopy; afterwards, they were investigated in terms of protein adsorption. Both UV-vis and XPS spectroscopy revealed the presence of Ag+ ions in all silver containing samples. By increasing the silver content, metallic Ag0 appears, the highest amount being observed for the sample with 1 mol% AgO2. Electron paramagnetic resonance measurements evidenced that the amount of spin-labeled serum albumin attached to the surface increases with the silver content. The results obtained by analyzing the information derived from atomic force microscopy and FT-IR measurements indicate that the occurrence of metallic Ag0 in the samples' structure influences the secondary structure of the adsorbed protein. Based on the results derived from the protein response upon interaction with the investigated glass calcium-phosphate based system, the optimal silver oxide concentration was determined for which the secondary structure of the adsorbed protein is similar with that of the free one. This concentration was found to be 0.5 mol%.

Second-century CE (common era) household pottery sherds found in the city of Napoca (present day Cluj-Napoca, Romania) in Roman Dacia were investigated by polarized light optical microscopy, X-ray powder diffraction, Fourier-transform infrared spectroscopy and cold field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to obtain information on technology, raw materials and site of production. Compositionally, all samples are similar with comparable fine and semi-fine microstructures and oriented microtextures. Optically, there is a gradual transition from microcrystalline to an amorphous illitic-muscovitic matrix. The small aplastic inclusions are mostly quartz and feldspar. Fine-grained carbonate aggregates are distributed inhomogeneously in the ceramic body. Well-preserved Middle Miocene foraminifera tests are characteristic of the ceramics. The gradual thermal changes of the matrix and the newly formed phases upon firing, such as ‘ceramic melilite’, Fe-gehlenite, clinopyroxene, glass, hematite and some maghemite support inferences regarding the technological constraints in producing the pottery. The firing took place in a mostly oxidizing atmosphere and the temperature extended from at least 850°C to >900°C. The Middle Miocene marly clay from the area surrounding the site shows similar mineralogical and micropalaeontological contents to those of the ceramic specimens and is the best candidate for the raw material used for local production of the Roman pottery.

The present study reports the results obtained by X-ray photoelectron spectroscopy (XPS) for new solid forms of antineoplastic agent 5-fluorouracil with anthelmintic piperazine obtained by liquid assisted ball milling and slurry crystallization methods as co-crystal and salt, respectively. The interest for these new solid forms of 5-fluorouracil with another drug consists in obtaining new compounds with potential pharmaceutical and biomedical applications. The XPS results bring additional deciding information on the atomic environments in the newly obtained solid forms of 5-fluorouracil with piperazine beside the earlier reported X-ray diffraction and infrared spectroscopy data. The deconvolution of N 1s core level spectra allows to distinguish unequivocally the protonated (salt) from hydrogen-bonded (co-crystal) nitrogen species based on the N 1s binding energy associated with the protonation of nitrogen atoms. The N 1s component around 402 eV observed only for the solid form obtained following the slurry route proves in this case the formation of a salt on basis of positively charged nitrogen resulted by protonation of secondary amine groups. Moreover, for the solid form obtained following the ball milling route, one notices a large negative shift of N 1s binding energy that supports the development of a co-crystal.

A new melt derived glass system consisting of Co2O3 added to 40P2O5·25B2O3·25CaO·10Na2O matrix was investigated in order to evaluate the influence of cobalt ions on the network structure. Multiple techniques, i.e. X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the local structure, the nature of the chemical bonding and the surface composition of these samples. The XRD measurements proved the vitreous character of samples with 0 and 3 mol% Co2O3. At higher cobalt oxide content (5, 7 and 10 mol%) the occurrence of a crystalline phase characteristic to Co2P4O12 has been observed. The complementary spectroscopic studies (FTIR and Raman) revealed that the incorporation of Co2O3 enhances the network connectivity and thereby the short range order in samples. Depending on their amount, the cobalt ions differently influence the borophosphate network via the tetraborate/triborate and metaphosphate/pyrophosphate ratios. For the sample containing 10 mol% Co2O3 the FTIR analysis indicates absorptions assigned to vibrations in CoO6 tetrahedra and suggests the presence of six-coordinated cobalt ions in Co3 + valence state. This study has proven that borophosphate based glasses are able to entrap cobalt ions, are sensitive from structural point of view to the amount of Co2O3 and possess interesting structural peculiarities.

Monodispersed silica-based microspheres have been prepared by hydrolysis and condensation of tetraethoxysilane (TEOS) in a water–ethanol mixed solution using dodecylamine (DDA) as hydrolysis catalyst and template. Core-shell samples were produced by electrostatic attraction and heterogeneous nucleation of alumina or mixed alumina and iron oxide (1:1) shells on mesoporous silica core microspheres. The iron oxide embedded in the shell structure may be considered both for contrast improvement in magnetic resonance imaging and for the local treatment of cancer by hyperthermia. SEM/TEM analysis proves the spherical shape of the silica particles, the shell development on their surface as well as the distribution of aluminum and iron in the whole shell. The outermost layer of the microspheres was primary investigated by XPS, while the structural characterization of the samples was achieved using XRD, FTIR, EPR and NMR techniques.

The aim of the present study was to asses the formation of solid forms between the 5-fluorouracil chemotherapy drug and the anthelmintic piperazine. Two new solid forms of antineoplastic agent 5-fluorouracil with anthelmintic piperazine were obtained by liquid assisted ball milling and slurry crystallization methods. The N H hydrogen bonding donors and C = O hydrogen bonding acceptors of 5-fluorouracil allow to form co-crystals with other drugs delivering improved properties for medical applications, as proved for other compounds of pharmaceutical interest. Both new solid forms were investigated using X-ray powder diffraction (XRD), differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy. The XRD results show that by both methods were successfully synthesized new solid forms of 5-fluorouracil with piperazine. According to FTIR results the form prepared by lichid assisted grinding process was obtained as co-crystal and the other one, prepared by slurry method, resulted as a salt.

The present archaeometric study focuses on a set of archaeological siliceous lithic tools that are assigned to the early Vinča culture period (Vinča A and Vinča B1). They were found in several pit-houses at Limba-Oarda de Jos (SW Transylvania, Romania), an open settlement that has been dated to 5,405-5,310 cal. BCE, a period in the Middle Neolithic. A total of 322 retouched tools and débitage pieces were typologically and macroscopically investigated. From these, 20 pieces were analyzed by polarized light optical microscopy (OM) and 10 pieces were analyzed by Fourier-transform infrared spectroscopy (FTIR) in order to identify compositional characteristics, define the petrographic type, and establish the spectral fingerprint of each material. Four petrographic types were discriminated: radiolarite, chert, fossiliferous chert, and siliceous limestone. Mineralogically, the tools primarily consist of a mass of microquartz and fibrous microquartz (called also ‘chalcedony’) associated with radiolarians remnants (in radiolarites); fossil shell fragments (in the fossiliferous chert); and limestone components, such as ooliths and pellets (in the siliceous limestone). All samples show distinct FTIR bands, most of which are assigned to microquartz, quartz, and fibrous microquartz. The deconvolution of the FTIR spectra in the 950-1300 cm-1 domain reveals the contribution of several other phases, such as calcite and clay minerals. The results support the assumption that the tools made of chert, fossiliferous chert, and siliceous limestone were produced at the site from nodules that probably originated from the Upper Jurassic chert-bearing limestone that crops out nearby in the Trascău Mts. The tools made of radiolarite were most likely brought to the site as finished products from the Trascău Mts.

Chromium doped lanthanum oxide synthesized by glycerol-assisted sol-gel route was heat treated at different temperatures up to 860 °C in order to investigate the effect of treatment temperature on the atomic environment in these samples. The addition of Cr2O3 to La2O3 catalyst support and catalytic promoter was considered because chromium is an interesting catalyst dopant. As the temperature rises from 100 to 860 °C, nanostructured La(OH)CO3, La2O2CO3 and La(OH)3 phases are developed in the treated samples. The crystallites size increases with treatment temperature from about 10 nm up to 30 nm, and at the same time a higher surface basicity is obtained, that would imply an enhanced catalytic activity or an improved behavior as catalyst substrate. The La2O2CO3 stable phase against moisture was obtained by relative low temperature synthesis. The tendency to atmospheric CO2 adsorption was evidenced for La(OH)3 phase developed in the samples treated at 650 and 860 °C. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses were used to evidence structural changes with influence on sample properties.

Bioactive glasses of the CaO–SiO 2 –P 2 O 5 system were synthesized through a sol–gel template method using polyethylene-glycol (PEG) with different molar weights. The samples were investigated by differential thermal analysis, X-ray diffraction and Fourier transform infrared spectroscopy. Electron paramagnetic resonance spectroscopy was employed to evidence possible structural defects and to reveal the response of the investigated glasses to gamma irradiation, and related effects on protein adsorption and samples bioactivity. PEG addition during samples synthesis induces structural changes within the glass matrix, which are dependent on PEG molar weights. At the same time, the use of PEG favors the occurrence of network defects. For the samples prepared with PEG of increased molar weight a lower apatite-forming ability was evidenced by the test carried out in simulated body fluid. It was also demonstrated that the network defects of samples affect the secondary structure of the protein adsorbed on the glass surfaces.

Doxorubicin-loaded magnetic nanocapsules, based on N-palmitoyl chitosan and magnetite, have been prepared using a double emulsion method. The morphology and size of the nanocapsules have been investigated by transmission and scanning electron microscopy. Magnetic nanocapsules were nearly spherical in shape, with a mean diameter in the nanometer range, and positive zeta potential. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Energy Dispersive X-ray analysis (EDX) confirmed the structure of composite magnetic nanocapsules. Magnetic nanocapsules exhibited suitable magnetic saturation, superparamagnetic behavior and good ability to incorporate a chemotherapeutic agent, properties which can be exploited in many different areas of biomedicine.

A composite coating consisting from a chitosan (Chit) thin film containing a new bioactive glass SiO2-CaO-P2O5 (BG) was investigated by cyclic voltammetry. The bioactive glass–biopolymer coating has certain porosity and is a good insulator comparing with the biopolymer film. The in vitro short-time stability of Chit and BG-Chit coatings on glassy carbon (GC) electrode is studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), during about 1 day of contact with a protein-free and acellular simulated body fluid (SBF) having an ion concentration nearly equal to that of human blood plasma. The EIS data indicated that after 5 hours of immersion in SBF the Chit dissolution and the adsorption of SBF ions on BG matrix were initiated causing the formation of a new outer biomimetic and biologically active hydroxyapatite protective layer. The CV and EIS measurements results recommend the use of composite BG–Chit coatings for in vivo devices (implants, prostheses and tissue engineering scaffolds).

The sol–gel derived 50SiO 2 ⋅30CaO⋅10Fe 2 O 3 ⋅10Dy 2 O 3 system was subjected to heat treatments at 500, 800 and 1200 °C in order to obtain crystalline phases of interest for biomedical applications. The structural changes were investigated by Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). Both FTIR and EPR results support the development of wollastonite, hematite and magnetite crystalline phases desirable for samples bioactivity and heating possibility for hyperthermia treatment. Dysprosium addition was considered for subsequent radioactivation of the samples that could extend their application to thermoradiotherapy.

A silver containing series of glasses starting from Ag-free 1.5B2O3 · SiO · CaO parent glass and ending with 3 mol% Ag2O was synthesized by the conventional melt quenching method and analyzed in order to correlate the composition and the structural peculiarities with the antibacterial effects. The structure and surface morphology of samples were characterized by X-ray diffraction (XRD), infrared (FTIR) and Raman spectroscopy, Scanning Electron Microscopy (SEM). X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the surface composition of the samples. The results indicate that all samples are vitreous and their local structure — mainly built by tetrahedral (BO4‐), triangular (BO3 and BO2O−) borate species (O representing an oxygen atom bridging two boron atoms) and silicate Q1, Q2, Q3 units — is reactive to the silver oxide addition. Based on XPS data, both Ag+ and Ag0 ions are present on the surface of detected silver nanoparticles. Ag nanoparticles (AgNPs) embbeded in glasses were evaluated for their antimicrobial activity against the gram-positive and gram-negative bacteria, i.e. Staphylococcus aureus and Escherichia coli bacteria. The antibacterial effect of investigated samples increases simultaneously with the Ag2O content and AgNP dimension. The proposed mechanism is discussed in relation with the local structure, Ag+/Ag0 ratio and AgNP dimensions.

Three silicate systems, i.e. pure SiO 2 , SiO 2 –CaO and SiO 2 –CaO–MgO, were prepared via sol–gel method in two different ways: ( i ) following the acid catalysed route (noted A), and ( ii ) the quick alkali mediated route (noted Q). The thermal behaviour was investigated for the as-prepared matrices and, according to differential thermal analysis (DTA) and thermogravimetric (TGA) analyses, the calcination temperature was establish at 600 °C in order to remove the synthesis residues and to stabilise the structure. Structural, textural and morphological investigations on the heat treated samples were performed before and after immersion in simulated body fluid (SBF) by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N 2 -adsorption and scanning electron microscopy (SEM). After 600 °C thermal treatment the samples remain mainly amorphous, only the CaO containing samples prepared by A route evidence an incipient Ca 2 SiO 4 crystalline phase. The N 2 -adsorption results showed that the specific surface area and the pore volume of the samples synthesised by Q route have higher values comparing with their counterparts prepared following the A route. Bioactivity tests carried out in SBF proved that the magnesium addition to the matrix obtained by Q route favours the hydroxyapatite (HA) self-assembly on the glass surface, and inhibits HA formation when it is added to the matrix obtained by A route. These results are supported by both FTIR and SEM analyses.

Zinc containing bioactive glasses were prepared by means of sol–gel procedure, in the presence of polyethylene glycol (PEG) considered as surfactant agent. Fourier transform infrared spectroscopy (FTIR), UV–Vis absorption spectroscopy and electron paramagnetic resonance spectroscopy (EPR) were employed to reveal the bioactive glass response to gamma irradiation in terms of defects generation. The results proved that gamma irradiation induces structural changes within the glass matrix, which are strongly dependent on the sample composition. ZnO addition to the glasses network was found to confer structural stability against gamma irradiation, while the use of PEG during the samples preparation favoured the generation of network defects especially in ZnO containing samples.

Well-defined calcium molybdate (CaMoO4) and hydroxyapatite (HAP) nanocrystals were developed by thermal treatment on the surface of a SiO2–CaO–P2O5–MoO3 amorphous precursor synthesised at room-temperature by sol–gel route. The structural and morphological characterisaions were performed by several techniques: energy dispersive X-ray spectroscopy, thermal analyses (DTA/TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, electron paramagnetic resonance. Complementary, Fourier transform infrared and Raman spectroscopies provided a clear picture regarding the short range order structure, emphasising beside the CaMoO4 phase development, the presence of HAP nanocrystals. The vibrational spectroscopic techniques proved to be valuable tools for evidencing very small HAP nanocrystallites that cannot be clearly observed by XRD and TEM analyses.

article The response of carbonate-rich illitic clay heated up to 1200 °C was investigated by means of electron paramag- neticresonance(EPR)inordertodefine the factors influencingtheshapeoftheresonancesignalsandtoestablish whether this method can be used for evaluation of firing temperature for clay-based ceramic objects. The results showthatthedominatinghyperfinesextet,atg ≅2,duetoMn 2+ ,isreplacedover700 °Cbyalargesignal,mainly due to Fe 3+ .O xidation of Mn 2+ (EPR active) to Mn 3+ (EPR silent) or Mn 4+ ,a nd Fe 2+ (EPR silent) to Fe 3+ (EPR active)respectively,combinedwithchangesintheirenvironmentproducetheresonancesignals.Thedestruction ofthecarrierssuchasFe-oxihydroxides,clinochlore,calcite,dolomite,alteredbiotite,illite andmuscovite,aswell astheformationofnewmineralsandglass arethemainmineralogical processesinfluencingthe widthof the res- onance signals. The results of this study can be used in conjunction with mineralogical and microstructural data for the investigation of technological conditions such as firing temperature and atmosphere related to archaeo

We synthesized a new boro-phosphate glass system with different %mol SeO2 content by conventional melt quenching technique. All samples were obtained in a glassy state with the vitreous structure confirmed by X-ray diffraction analysis. Scanning electron microscopy (SEM) revealed some non-homogeneous domains on the glasses surface, and their tendency to link each other once the selenium oxide content increases. Energy-dispersive X-ray analysis (EDAX) indicated similar elemental composition in different regions of each sample. X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the elemental composition at the sample surfaces, and Fourier transform infrared (FT-IR) spectroscopy was used to determine the structural groups in the obtained glass structure. Based on FT-IR results, the glass structure at short range order consists mainly of small phosphate units such as pyrophosphate (i.e. P2O74 − dimmers or terminating groups at the end of phosphate chains) and some metaphosphate (i.e. PO3− middle groups in the phosphate chains) units. The boron atoms are mainly placed in three-coordinated sites in BO3 or BO2O− units. A small contribution of BO4− units was also detected from the FT-IR spectra of glasses. For SeO2 content higher than 5 mol%, the modifier role of selenium ions is strongly reflected on the local structure dominated in this case by pyrophosphate units.

The aim of the present study was to produce and characterize three-dimensional (3D) interconnected macroporous glass-ceramic scaffolds with different amounts of zinc for tissue engineering applications. The scaffolds were obtained using sol–gel method without and with addition of polyethylene-glycol (PEG) combined with sacrificial template method. The structural and morphological properties of these samples were investigated using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, as well as scanning electron microscopy (SEM). PEG addition during scaffold synthesis produced changes on their structural properties that after heat treatment led to an increased crystalline phase content as compared to the sample prepared without PEG addition. At the same time, the scaffolds prepared with PEG showed higher pore interconnectivity and greater apatite-forming ability, as evidenced by the bioactivity test in simulated body fluid.

The aim of this study was to prepare and to characterize the structure of Al2O3–3YSZ composites with 5% TiO2 addition as well as the surface modification upon treatments with SnF2 and NaBF4, respectively. SEM micrographs showed the controlled densification of the composites as an effect of 3YSZ and TiO2 addition to alumina matrix. By FTIR and XRD, the characteristics of Al-O and Zr-O vibrations, respectively, the diffractions lines related to α-corundum and zirconia in tetragonal phase were discussed. Qualitative and quantitative results obtained by XPS and ATR FTIR demonstrated that the proposed materials are more sensitive to SnF2 than to NaBF4 treatment.

Inorganic–organic hybrid materials like clay polymer nanocomposites (CPN) are a topic of increasing interest due to their implications in a broad range of applications including tissue engineering scaffolds and drug delivery systems. Our study is focused on CPN developed from polyvinyl alcohol and medical kaolinitic clay prepared by solution intercalation and mechanical mixing methods and characterised by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques. Both components and nanocomposite materials were tested in simulated body fluid enriched with serum albumin for the assessment of the first biological response at the interface with entities of the living tissues. The protein attachment on the material surface was primarily revealed by N 1s photoelectron peak related to the protein amino groups. For both CPN the FTIR spectra evidenced characteristic absorption bands of amides I and II of the protein.

The aim of our study is to compare the structural and biological tolerance of novel Al2O3/3Y-TZP composites with ceria respectively titania addition (5 wt%). Scanning electron microscopy, X-ray diffraction, infrared spectroscopy and XPS results are reported for structural characteristics and surface modifications upon different fluoride treatments. The biocompatibility of the samples was evaluated using an animal model (rabbit). The explants were analyzed at a specific period (6 weeks).The sections of implanted bone area were subjected to histological evaluation. Upon correlating the structural properties and in vivo evaluation, we concluded that the addition of both TiO2and CeO2to Al2O3/3Y-TZP implies similar properties and satisfactory biological tolerance. With respect to the surface treatment, qualitative and quantitative results show that the alumina/zirconia with titania addition are more sensitive to fluoride treatment.

Sol-gel derived 60SiO(2).20Al(2)O(3).10Fe(2)O(3).10Dy(2)O(3) (mol%) glass and vitro-ceramic samples obtained after high temperature treatment were investigated with respect to structure, magnetic behaviour, response to simulated body fluid (SBF) and bovine serum albumin (BSA). After heat treatment, the iron preponderantly crystallises as magnetite and hematite. The field-dependent magnetisation measurements support a soft ferrimagnetic, nearly superparamagnetic behaviour. After soaking in SFB/BSA solutions, the analysis of the outermost surface layer by X-ray photoelectron spectroscopy shows the attachment of the protein and the self-assembly of a calcium containing phase. (C) 2011 Elsevier B.V. All rights reserved.

Lime phosphosilicate and soda lime phosphosilicate glasses prepared by sol-gel method were precursors of bioactive glass-ceramics. The structure of the samples and the distribution of the [SiO4] units was investigated by X-ray diffraction and infrared spectroscopy. Human osteosarcoma cell line (MG63) was used for the in vitro cellular response. DNA staining (Hoechst 33258) assay was performed for assessing samples colonization.

This article reports a comparison of the structural and textural properties of bioglass–hydroxyapatite (HA) composites obtained in the SiO2–CaO–P2O5 system by sol–gel method, with different amounts of hydrogen peroxide (3% H2O2) or water (H2O). X-ray diffraction, Raman, and FT-IR spectroscopy reveal the presence of nanocrystalline HA. Scanning electron microscopy images illustrate that the HA phase is mainly distributed on the glass surface. The results point out that the sintering at 550 °C of a sol–gel derived SiO2–CaO–P2O5 bioglass leads to a single crystalline phase of HA, and validate a new processing method for obtaining bioglass–HA composites. Structural analyses of the investigated composites indicate the existence of a silicate network built up from Q3 and Q2 units. The replacement of water with hydrogen peroxide has as consequence the increase of depolymerization degree of silica network. Textural properties were investigated with N2-adsorption technique. The composites prepared with hydrogen peroxide exhibit a more uniform and narrow mesoporous distribution that recommends them for drug uptake and release applications. It was found that the specific surface area and pore volume are clearly influenced by the H2O2(H2O):TEOS molar ratio.

The behaviour of iron containing aluminosilicate samples in Kokubo's simulated body fluid (SBF) and in SBF enriched with bovine serum albumin (BSA) has been investigated. Crystalline samples of (80-x)SiO2 X 20Al2O3 X Fe2O3 system, with x = 5, 10 or 15 mol%, obtained by sol-gel method and heat treated at 1200 degrees C in air for 24 h. Data on electrical conductivity, calcium, phosphorous and potassium concentrations in simulated body fluids after samples soaking in static regime at 37 degrees C, for several periods up to 14 days, were used to estimate the dynamics of these cations on the interface of aluminosilicate samples with SBF, and with SBF containing BSA. The UV-visible and fluorescence spectra recorded from the simulated body fluids after immersion of the investigated aluminosilicate samples evidence changes function on immersion time and Fe2O3 content.

A series of vitreous samples from the system xAg2O·(100 − x)[2P2O5·CaO·0.05GeO2] where x values vary from 0 to 10 mol% were prepared and investigated through infrared and Raman spectroscopy, X-ray diffraction and scanning electron microscopy (SEM).The homogeneous vitreous character of the samples was confirmed by both X-ray diffraction and SEM measurements through all compositional range. FT-IR and Raman spectroscopy revealed a local network structure mainly based on Q1, Q2 and Q3 tetrahedrons connected by P–O–P linkages. A gradual depolymerization of the phosphate chains was observed with the addition of the silver oxide.The surface structure of sample having the highest concentration of silver oxide (10 mol%) has been studied in vitro by immersion in simulated body fluid (SBF) at 37 °C. Different spectroscopic techniques (X-ray diffraction, SEM, FT-IR and Raman) are proving extremely efficient for in situ monitoring of structural changes of this sample reacting with SBF.

The present paper reports the influence of silver oxide addition on the local structure of 2P 2 O 5 · CaO · 0.05ZnO glass matrix. The glass samples were investigated through several methods: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), infrared absorption (FT-IR) and Raman scattering. The X-ray diffraction patterns confirm the vitreous character of these samples over the explored compositional range and the SEM pictures confirm this information. The phosphate structural units of the network former are assessed from FT-IR and Raman spectra as ultra-, meta-, pyro- and orthophosphate units. A slight structural depolymerization process of these phosphate-based glasses was evidenced for higher silver oxide content. In vitro behavior of the bulk glass sample with the highest silver oxide content was tested by immersion in simulated body fluid (SBF). X-ray diffraction and SEM measurements made on the SBF treated sample revealed growth of a crystalline phase on the surface sample.

Heavy metal oxide glasses and vitroceramics belonging to the Bi2O3–GeO2–Gd2O3 system are investigated. The changes induced by heat treatment in the elemental composition on sample surfaces are related to the local order changes. O 1s and Bi 4f core level X-ray photoelectron spectra evidence the local order changes caused by gadolinium addition to the Bi2O3–GeO2 matrix and by partial crystallisation of the precursor glass samples. The addition of gadolinium to the Bi2O3–GeO2 glass matrix leads to a reduction of the number of bridging oxygens and a depolymerisation of the glass structure. The number of bridging oxygens increases on heat treatment of the samples. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The in vitro behavior of x Ag 2 O (100 − x )[50P 2 O 5 · 30CaO · 20Na 2 O] glasses (0.14 ⩽ x ⩽ 20 mol%) is investigated in simulated body fluid (SBF) mainly with respect to bioactivity and silver ions release. In order to estimate the biodegradability and bioactivity, the samples were soaked in SBF, which has almost equal ions concentration to those of human blood plasma, and kept at 37 °C for fixed periods of time up to 18 days. After the fixed periods of time analyses were performed on the SBF solutions. Calcium and silver ions concentration of SBF after different soaking times of the glass samples were primarily examined. Conductivity data support the assumption that the released silver ions are reduced in SBF and their release is obstructed by growth of the bioactive layer on the glass surface. X-ray diffraction and infrared analysis attest the development on glass surface of a hydroxyapatite type layer.

Glass stability and the structural role of iron oxide in x Fe 2 O 3(100-x)[ B 2 O 3– MO ] systems ( M=Ca , Sr or Ba , 0≤x≤30 mol%) were estimated from differential thermal analysis. The results suggest structural changes characteristic for the transition from short range to intermediate range order as the cationic field strength of the alkaline earths increases. In contrast, the iron addition has an opposite effect and determines a higher glass stability of these systems.

X-ray photoelectron spectroscopy (XPS) was used to evidence the effect of the Bi2O3 to SiO2 ratio and of partial crystallisation on the electronic charge density around the atoms entering silica–bismuthate glasses of nominal composition 0.01Fe2O3⋅0.99[xSiO2⋅(100−x)Bi2O3] with 10 ≤ x ≤ 60 mol% . The core level spectra show significant composition dependent changes in binding energy, and the full width at half maximum of photoelectron peaks both of cations and of oxygen atoms. The analysis reveals changes in electron density correlated with the ionic and covalent character of the samples. The shift in binding energy suggests charge transfer from silicon and oxygen atoms to bismuth atoms. Contrary to the expected behaviour in conventional silicate oxide systems, the results indicate an increase of ionicity for silicon and of covalency for bismuth atoms. The same evolution of ionicity/covalency is observed after partial crystallisation.

The function of three types of bacteriorhodopsins was compared: the wild-type, the bleached and retinal reconstituted and retinal deficient bacteriorhodopsin after retinal addition. The apparent pKa of the proton acceptor group for the bleached BR and retinal deficient BR shifted toward higher pH values compared to the wild-type BR. Fitting the photocycle model to the absorption kinetic signals for all three proteins showed the existence of the same intermediates, but the time-dependent concentration of the intermediates was different. Although measurements were made at pH 7, the absorption kinetics and photoelectric signals in both retinal reconstituted samples acted as wild-type bacteriorhodopsin at significantly higher pH. Below pH 3 the retinal deficient and reconstituted sample bleached. These results suggested that the added retinal was not able to rebind in the same position in the protein as in native bacteriorhodopsin. This points out that care should be taken, when bleached bacteriorhodopsin is reconstituted with different retinal analogs. 2006 Elsevier B.V. All rights reserved.

Sodium salt of chloride, bromide and iodide were used to elucidate the effect of the size of the anion on the binding to pharaonis halorhodopsin and its transport during the photocycle of this retinal protein. Spectroscopic titration revealed an apparent strong binding constant of 2 mM for chloride, 0.23 mM for bromide and 5 mM for iodide. In the case of iodide a second, week binding constant of about 10 M could be estimated. This second binding constant was similar to that observed earlier for nitrate. By changing the halide ions, only the transitions in the second half of the photocycle were affected, which contained intermediates N, O, and HR′. The O to HR′ transition becomes faster with increasing ion volume, meaning that the ion uptake is accelerated. This effect shows a direct correlation with the ion radius. With increasing ion concentration the N–O–HR′ equilibrium changed in such a way that the accumulated O tended to decrease. This tendency was overruled in iodide, by the appearance of the second binding constant. The increasing iodide concentration, up to 100 mM decreases the accumulation of the intermediate O, due to kinetic reasons, but at higher ion concentration the amount of O increases, although its decay becomes faster. This effect correlates with the appearance of the second iodide bound to the protein.

Structural changes induced by temperature rising in binary silico-bismuthate glasses are investigated by differential thermal analysis. Several exothermic peaks are recorded for all samples. Progressive substitution of Bi 2 O 3 by SiO 2 contributes to the structural relaxation of vitreous network and leads to diminishing of the melting temperature, even as SiO 2 content reaches 40 mol%. Glass stability is enhanced by addition of silicon dioxide.

Differential thermal analysis (DTA) under nonisothermal conditions was carried out on glasses of xFe2O3(80−x)Bi2O3·20Ga2O3 system (x=0, 5, 10, 20 mol%). The crystallization has been studied by using DTA. From the dependence of the glass transition temperature (Tg) on the heating rate (a), the glass transition activation energy (Ea) was derived. Iron oxide addition to gallium-bismuthate glass matrix induces minor changes in glass thermal stability but causes continuous decrease of melting temperature.

Glasses of various compositions belonging to the x Fe 2 O 3 · (80 − x )Bi 2 O 3 · 20Ga 2 O 3 system were prepared via a melt quenching technique. The dielectric properties of samples, dielectric constant e r and loss tan δ , were investigated as a function of iron content (0 ⩽ x ⩽ 20 mol%), temperature (from room temperature up to 200 °C) and frequency (1, 10 and 100 kHz). The temperature at which the dispersion of the dielectric constant starts to be observed was determined as function on iron content.

Atomic environment of x Fe 2 O 3·(80-x) Bi 2 O 3·20 Ga 2 O 3 heavy glasses (0≤x≤20 mol %) was investigated with respect to electronic structure of the samples. Data obtained from Bi 4f, Ga 2p, Fe 2p, and O 1s core-level photoelectron spectra indicate changes in the local order on the account of partial substitution of bismuth by iron. The bismuth cations behave essentially as network formers while the iron and gallium ones acts as network modifiers. The number of nonbridging oxygens depends on Fe 2 O 3 content.

Glass transition and crystallization temperatures established from differential thermal analysis (DTA), density, molar volume and ionic field strength changes induced by the addition of Fe 2 O 3 to the CaO-P 2 O 5- SiO 2 glass matrix, are correlated in order to understand the structural role of iron oxide in the investigated glasses and to discover the structural evolution of the samples as a function of composition. The compactness degree in calcium-silica-phosphate glasses increases when Fe 2 O 3 is added. The results suggest structural changes characteristic of intermediate range order.

Dielectric constant εr and loss tan δ of x Fe 2 O 3 · 45(3.34 CaO · P 2 O 5)(55 - x) SiO 2 samples were investigated as a function of composition (0 ≤ x ≤ 30 mol %), temperature and frequency. The samples are characterized by relatively high dielectric constants, which denote bonding defects in the glass network. At all temperatures and frequencies investigated, the dielectric loss for the P 2 O 5- CaO-SiO 2 matrix is lower than that for iron-containing samples. The dielectric constant is higher for the glass matrix than for the iron-containing samples only in the first part of the temperature range. Where the dielectric constant of the glass matrix is higher than the corresponding value for the iron-containing samples the temperature range, exponentially narrows with the decrease of frequency. The dielectric loss in the iron-containing samples is mainly attributed to iron ions conduction.

The EPR and magnetic susceptibility data for x V 2 O 5 (1− x )[2B 2 O 3 ·Li 2 O] glasses indicate the presence of both V 4+ and V 5+ valence states. The magnetic susceptibility investigation shows that only a small fraction of vanadium ions are in the V 4+ state and the N V 4+ / N V 5+ ratio decreases when V 2 O 5 content increases. The EPR spectra recorded from samples with low V 2 O 5 content ( x ≤5 mol%) show a well resolved hyperfine structure typical for isolated vanadyl ions in a ligand field of near octahedral ( O h ) symmetry. For x >20 mol% the EPR spectra may be considered a superposition of two signals: one with a resolved hyperfine structure typical for isolated VO 2+ ions in a C 4v symmetry, and the other a broad line without structure, at g ≈1.96, assigned to associated vanadium ions. The clustered ions are formed due to the dipole–dipole interactions between V 4+ ions and their number increases with V 2 O 5 content. At higher concentrations ( x >20 mol%), V 2 O 5 behaves as glass network former together with B 2 O 3 .

Glass transition and nucleation temperatures as well as densities and molar volumes of x Bi 2 O 3·y PbO (0.5≤x/y≤4) are reported. The glass transition temperature and molar volume are further analysed in terms of structural data. The obtained results indicate the occurrence of structural changes from short range to long range order induced by the heat treatment applied at 550°C, as per DTA results. These changes depend on the x/y ratio between Bi 2 O 3 and PbO content. The compositional variation of the molar volume of untreated and heat-treated samples are evidences that both Bi 2 O 3 and PbO play the role of network formers.

Structural and magnetic properties of B 2 O 3– SrO – Fe 2 O 3 glasses were explored by a controlled doping of 2B 2 O 3· SrO vitreous matrix with iron oxide. The information concerning the structural units involving iron ions, their valence states and the types of interactions between them, was obtained using electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility measurements.

Beta and gamma molar activities of xThO2·(100−x)[2P2O5·Na2O] glasses were determined in the composition range 0

The study reports the preparation and characterization of powders consisting of the different phases of calcium phosphates that were obtained from the naturally derived raw materials of sea-shell origins reacted with H 3 PO 4 . Species of sea origin, such as corals and nacres, attracted a special interest in bone tissue engineering area. Nacre shells are built up of calcium carbonate in aragonite form crystallized in an organic matrix. In this work two natural marine origin materials (shells of echinoderm Sputnik sea urchin — Phyllacanthus imperialis and Trochidae Infundibulum concavus mollusk) were involved in the developing powders of calcium phosphate based biomaterials (as raw materials for bone-scaffolds) by hotplate and ultrasound methods. Thermal analyses of the as-prepared materials were made for an assessment of the thermal behavior and heat treatment temperatures. Samples from both sea shells each of them prepared by the above mentioned methods were subjected to thermal treatments at 450 °C and 850 °C in order to evaluate the crystalline transformations of the calcium phosphate structures in the heating process. By X-ray diffraction analyses various calcium phosphate phases were identified. In Sputnik sea urchins originated samples were found predominantly brushite and calcite as a small secondary phase, while in Trochidae I. concavus samples mainly monetite and HA phases were identified. Thermal treatment at 850 °C resulted flat-plate whitlockite crystals — β-MgTCP [(Ca, Mg) 3 (PO 4 ) 2 ] for both samples regardless the preparation method (ultrasound or hotplate) or the targeted Ca/P molar ratio according with XRD patterns. Scanning electron microscopy and Fourier transformed infrared spectroscopy were involved more in the characterization of these materials and the good correlations of the results of these methods were made.

Adsorption and structural changes that occur upon interaction between methemoglobin (MetHb) and 5-methyl-aminomethyl-uridine forming enzyme (MnmE) with the surface of a bioactive glass (BG) were investigated by Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The effect of glutaraldehyde (GA) as a coupling agent for protein adsorption on BG was also investigated. The comparative analysis of FTIR spectra recorded from lyophilized proteins and from bioactive glass surface after protein adsorption was considered in order to obtain information about the changes in the secondary structure of the proteins. XPS data were used to determine the surface coverage. The unfolding of adsorbed proteins due to interactions between the internal hydrophobic protein domains and the hydrophobic BG surface was evidenced. After adsorption, the amount of α-helix decreases and less ordered structures (turns, random coils and aggregates) are preponderant. These changes are less pronounced on the BG functionalized with GA, suggesting that the treatment with GA preserves significantly larger amounts of α-helices in the structure of both proteins after adsorption.

The following glass systems x(CuO·V2O5)(100 − x)[2P2O5 · PbO] and x·(MnO·V2O5)(100 − x)[2P2O5 · Na2O] with 0 ⩽ x ⩽ 40 mol% were prepared and investigated by EPR spectroscopy. The obtained data suggest an octahedral-tetrahedral (Td) distorted local symmetry for Cu2+ and Mn2+ ions, and a square—pyramidal (C4v) coordination for V4+ ions. The mixed exchange pairs (Cu2+−V4+, Mn4+) appear at high transition metal oxides content (x > 10 mol%).

Dielectric and magnetic behaviour of the YBa2(Cu1 − xMx) 3O7 − δ (MZn, Ni, Cr and x ⩽ 0.10) system was investigated. The results suggest a diffuse phase transition to a relaxor-type ferroelectric state. Taking into account the double-well model of high-temperature superconductivity and using double-well parameters from the Abrahams-Kurtz-Jamieson (AKJ) relation for ferroelectric phase transition in oxide perovskite, the unrenormalizable barrier heights are calculated. The values could be related to an excitonic mechanism of superconductivity. Small anomalies observed in the static dielectric constants coincide with the Neel points of the corresponding nonsuperconductive phases in YBa2(Cu1 − xMx)3O7 − δ compounds.