X-ray Microanalysis Of Elements Research Articles

Optimal Energy Dispersive X-ray Microanalysis of Low-Z Elements

Optimal Energy Dispersive X-ray Microanalysis of Low-Z Elements

Characterization and Customization of Individual EDS Detectors to Improve X-ray Microanalysis of Light Elements

Characterization and Customization of Individual EDS Detectors to Improve X-ray Microanalysis of Light Elements

Synthesis, properties, and pyrolysis of organoalumoxanes modified with refractory metals

Organoalumoxane oligomers modified with refractory metals (zirconium, hafnium or chromium) were synthesized. Their physico-chemical and fiber-forming properties were studied. Models of the group and elemental composition of oligomeric molecules of organoalumoxanes containing zirconium, hafnium or chromium were proposed. Based on the results of X-ray elemental microanalysis (SEM) and X-ray diffraction, it was found that pyrolysis of metal-containing organoalumoxanes at 1500°C in air results in the microcrystalline ceramic powders of corundum composition, modified with refractory metal oxides.

Features of formation of the Al–Ni–Zr system alloy structure obtained by reducing oxide compounds by aluminothermy using SHS metallurgy

This work is focused on establishing the regularity of the effect of zirconium (2.21; 3.29; 3.69 and 6.92 wt.% Zr) on structure formation, the nature of distribution of elements and the microhardness of structural components in the Al–Ni–Zr system alloys obtained by aluminothermy using the SHS metallurgy. Regularities of the formation of structural components and their microhardness depending on the content of zirconium in Al–Ni alloys (50 wt.%) have been identified and scientifically substantiated. Structural components were identified by the methods of electromicroscopic studies and X-ray microanalysis of elements. The structure of the initial alloy consists of Al3Ni2 (β′-phase) and Al3Ni nickel aluminides. Zirconium doping of the alloy in the amount of 2.21 wt.% leads to crystallization of zirconium nickel aluminide Al2(Ni,Zr). With further increase in the content of zirconium (more than 2.21 wt.% Zr), complex alloyed intermetallic compounds crystallize – Zr, W, Si aluminides and Ni zirconides. A regularity was established in the decrease of the solubility of nickel in nickel aluminides Al3Ni2 and Al3Ni and their microhardness as the zirconium content increases in the Al–Ni–Zr alloys from 2.21 to 6.92 wt.%. In nickel aluminide with zirconium Al2(Ni,Zr), this contributes to a decrease in the solubility of Ni, Al and increase in the concentration of Si and Zr. Zirconium doping of the Al–Ni alloy in the amount over 2.21 wt.% contributes to an increase in hardness (HRA), despite a decrease in the microhardness of the metal base (Al3Ni2, Al3Ni and Al2(Ni,Zr)). The main reason for increasing the hardness of the Al–Ni–Zr alloys is the crystallization of complex-alloyed intermetallides – Zr, W, Si aluminides and nickel zirconide, which probably have an increased microhardness. Thus, zirconium doping of the Al–Ni alloy makes it possible to obtain a plastic metal base from nickel aluminides Al3Ni2, Al3Ni and Al2(Ni,Zr) and complex-alloyed intermetallides with high hardness.

Selective Supramolecular Recognition of Nitroaromatics by a Fluorescent Metal–Organic Cage Based on a Pyridine-Decorated Dibenzodiaza-Crown Macrocyclic Co(II) Complex

Two isomorphous fluorescent (FL) lantern-shaped metal-organic cages 1 and 2 were prepared by coordination-directed self-assembly of Co(II) centers with a new aza-crown macrocyclic ligand bearing pyridine pendant arms (Lpy). The cage structures were determined using single-crystal X-ray diffraction analysis, thermogravimetric, elemental microanalysis, FT-IR spectroscopy, and powder X-ray diffraction. The crystal structures of 1 and 2 show that anions (Cl- in 1 and Br- in 2) are encapsulated within the cage cavity. 1 and 2 bear two coordinated water molecules that are directed inside the cages, surrounded by the eight pyridine rings at the "bottom" and the "roof" of the cage. These hydrogen bond donors, π systems, and the cationic nature of the cages enable 1 and 2 to encapsulate the anions. FL experiments revealed that 1 could detect nitroaromatic compounds by exhibiting selective and sensitive fluorescence quenching toward p-nitroaniline (PNA), recommending a limit of detection of 4.24 ppm. Moreover, the addition of 50 μL of PNA and o-nitrophenol to the ethanolic suspension of 1 led to a significant large FL red shift, namely, 87 and 24 nm, respectively, which were significantly higher than the corresponding values observed in the presence of other nitroaromatic compounds. The titration of the ethanolic suspension of 1, with various concentrations of PNA (>12 μM) demonstrated a concentration-dependent emission red shift. Hence, the efficient FL quenching of 1 was capable of distinguishing the dinitrobenzene isomers. Meanwhile, the observed red shift (10 nm) and quenching of this emission band under the influence of a trace amount of o- and p-nitrophenol isomers also showed that 1 could discriminate between o- and p-nitrophenol. Replacement of the chlorido with a bromido ligand in 1 generated cage 2 which was a more electron-donating cage than 1. The FL experiments showed that 2 was partially more sensitive and less selective toward NACs than 1.

Differences in foliar phosphorus fractions, rather than in cell-specific phosphorus allocation, underlie contrasting photosynthetic phosphorus use efficiency among chickpea genotypes.

Although significant intraspecific variation in photosynthetic phosphorus (P) use efficiency (PPUE) has been shown in numerous species, we still know little about the biochemical basis for differences in PPUE among genotypes within a species. Here, we grew two high PPUE and two low PPUE chickpea (Cicer arietinum) genotypes with low P supply in a glasshouse to compare their photosynthesis-related traits, total foliar P concentration ([P]) and chemical P fractions (i.e. inorganic P (Pi), metabolite P, lipid P, nucleic acid P, and residual P). Foliar cell-specific nutrient concentrations including P were characterized using elemental X-ray microanalysis. Genotypes with high PPUE showed lower total foliar [P] without slower photosynthetic rates. No consistent differences in cellular [P] between the epidermis and mesophyll cells occurred across the four genotypes. In contrast, high PPUE was associated with lower allocation to Pi and metabolite P, with PPUE being negatively correlated with the percentage of these two fractions. Furthermore, a lower allocation to Pi and metabolite P was correlated with a greater allocation to nucleic acid P, but not to lipid P. Collectively, our results suggest that a different allocation to foliar P fractions, rather than preferential P allocation to specific leaf tissues, underlies the contrasting PPUE among chickpea genotypes.

Knockdown of E1- and E2-ubiquitin enzymes triggers defective chorion biogenesis and modulation of autophagy-related genes in the follicle cells of the vector Rhodnius prolixus.

In insects, the last stage of oogenesis is the process where the chorion layers (eggshell) are synthesized and deposited on the surface of the oocytes by the follicle cells. Protein homeostasis is determined by the fine-tuning of translation and degradation pathways, and the ubiquitin-proteasome system is one of the major degradative routes in eukaryotic cells. The conjugation of ubiquitin to targeted substrates is mediated by the ordered action of E1-activating, E2-conjugating, and E3-ligase enzymes, which covalently link ubiquitin to degradation-targeted proteins delivering them to the proteolytic complex proteasome. Here, we found that the mRNAs encoding polyubiquitin (pUbq), E1, and E2 enzymes are highly expressed in the ovaries of the insect vector of Chagas Disease Rhodnius prolixus. RNAi silencing of pUbq was lethal whereas the silencing of E1 and E2 enzymes resulted in drastic decreases in oviposition and embryo viability. Eggs produced by the E1- and E2-silenced insects presented particular phenotypes of altered chorion ultrastructure observed by high-resolution scanning electron microscopy as well as readings for dityrosine cross-linking and X-ray elemental microanalysis, suggesting a disruption in the secretory routes responsible for the chorion biogenesis. In addition, the ovaries from silenced insects presented altered levels of autophagy-related genes as well as a tendency of upregulation in ER chaperones, indicating a disturbance in the general biosynthetic-secretory pathway. Altogether, we found that E1 and E2 enzymes are essential for chorion biogenesis and that their silencing triggers the modulation of autophagy genes suggesting a coordinated function of both pathways for the progression of choriogenesis.

Colloidal Stabilizer-Assisted Polymerization-Induced Precipitation Method for Colloidally Stable Polyacid Particles.

Near-monodispersed, colloidally stable, submicrometer-sized poly(acid phosphoxy ethyl methacrylate) (PAPEMA) latex particles were synthesized by free-radical dispersion polymerization using poly( N-vinylpyrrolidone) (PNVP) as both a steric colloidal stabilizer and a precipitating agent. Polymerization in the absence of PNVP led to a homogeneous transparent solution of PAPEMA, which indicates that the PNVP is essential for latex formation and the complex of PNVP and PAPEMA was formed during the dispersion polymerization. Dispersion copolymerizations with a divinyl cross-linking comonomer (∼20 wt % based on acid phosphoxy ethyl methacrylate) were also successful in synthesizing near-monodispersed, colloidally stable cross-linked PAPEMA latex particles, and the softness and p Ka values of the resulting PAPEMA latex particles can be controlled by varying the divinyl comonomer concentration. These sterically stabilized latex particles were characterized by electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, elemental microanalysis, and Fourier transform infrared spectroscopy. Characterization results indicated that the PNVP colloidal stabilizer was likely to be located homogeneously on the particle surfaces and within the interior of particles. Finally, it was demonstrated that the PAPEMA latex particles worked as an effective surface modifier for metal surfaces.

Determination of light elements C, N, O in various minerals and synthetic compounds using X-ray microanalysis

The goal of the study is developing of the methodology of X-ray microanalysis of light elements C, N and O which are jointly present in various minerals and synthetic compounds, including ultrafine diamonds, carbon filamentous fibers, etc. An accelerating voltage of 10 kV high enough to reduce the contribution of the sample surface to the intensity of the lines, and at the same time prevent from the overestimation of the corrections for the line absorption was used. The beam current ranged within 90 - 120 nA. The lines of nitrogen and oxygen are particularly strongly absorbed by carbon. The background intensity is measured near the line. In the region of Kα lines of C and O, the background changes linearly, while for oxygen exhibits a large slope. The shape of continuous X-ray spectrum from the sample at 10 kV in the region of the nitrogen line can be approximated by a polynomial dependence. We used a differential mode of the amplitude discrimination of the signal. It is shown that the position and shape of the carbon line depends on the type of the chemical bond: from covalent (diamond, graphite) to a more ionic bond with oxygen (carbonates). Wide in diamond and graphite Kα lines are shifted in carbonates to the shortwave region and substantially narrowed. An additional maximum appears due to admixing of the wave functions of 2p electrons of carbon to the wave functions of 2s electrons of oxygen. The errors related to the influence of the type of chemical bond on the shape of the spectra can be avoided by the analysis of the integrated intensities. In some cases, the resistance of the samples to the impact of the electron beam is increased by the raster mode of size 5-8 micron or by moving the sample within the area ~100 x 100 pm 2 . Calculation of the concentrations was carried out in the PAP program using B. L. Henke absorption coefficients. Some errors in the correction factors for the line absorption are usually corrected by selecting the absorption coefficients. The detection limit of carbon is 0.10 % wt. and for oxygen in carbonates it ranges within 0.39 - 0.90 % wt., whereas in the samples grown from nano-diamond colloids attains 0.75 wt. %.

Effects of pH and bicarbonate on the nutrient status and growth of three Lupinus species

High pH, and high bicarbonate (HCO3−) and calcium (Ca) availability characterise calcareous soils. High [Ca] only partially explains why some Lupinus species are calcifuge, so we explored high [HCO3−] and high pH. We grew six Lupinus genotypes in hydroponics with pH 5, 6.5 and 8a (adjusted by KOH), and 8b (adjusted by KHCO3). Leaf symptoms and areas, root appearance and biomass were recorded; whole leaf and root nutrient concentrations, and leaf cellular phosphorus (P), Ca and potassium (K) concentrations were determined using elemental X-ray microanalysis. Chlorosis was observed in young leaves at high pH for L. angustifolius and L. cosentinii, and P deficiency at high pH for all genotypes. High pH decreased iron (Fe) and zinc (Zn) uptake in all genotypes. It also decreased lateral root growth, the uptake of P, K, Ca, and manganese (Mn) by all sensitive species; and translocation of P, Fe, Zn, Mn, and Ca to leaves in most sensitive species. However, leaf [Ca], leaf [K], [K] within each measured cell type, and translocation of K and Ca to leaves of L. pilosus and L. cosentinii at pH 8 were greater than at pH 5 and 6.5. Compared with pH 8a, all L. angustifolius genotypes translocated more P, Fe, Zn, Mn and K from roots to leaves at pH 8b. High pH did not affect the leaf cell types that accumulated P and Ca, but decreased the leaf cellular [P]. Lupinus angustifolius and L. cosentinii were sensitive to high [HCO3−] and/or high pH; L. pilosus was relatively tolerant. High pH decreased lateral root growth and nutrient uptake, inhibiting growth of sensitive species. High [HCO3−] diminished the negative effect of pH 8 on nutrient translocation to leaves in most L. angustifolius genotypes. This knowledge provides critical insights into the habits of Lupinus species to guide breeding of calcicole plants.

Water-Dispersible Bismuth-Organic Materials with Computed Tomography Contrast Properties.

Two bismuth-organic network polymers were synthesized by means of a one-step polycondensation reaction between an aromatic dithiol/trithiol and triphenylbismuth. The materials were characterized by solid-state UV-vis spectroscopy, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, elemental microanalysis, and thermogravimetric analysis. Uniform dispersion of the hydrophobic and water-insoluble bismuth-containing polymers in aqueous media was achieved by the addition of 2 kDa poly(ethylene glycol) methyl ether thiol. This enabled quantitative phantom imaging experiments on a clinical computed tomography (CT) scanner, which showed that the coordination polymers possessed strong CT contrast properties. The observed X-ray attenuation properties of each coordination polymer were correlated with its bismuth payload. The X-ray opacity, thermal and chemical stabilities, and aqueous dispersibility of this novel class of bismuth-organic materials make them potentially useful as biomedical CT contrast agents and radiopaque materials.

Physiological response of Lactuca sativa exposed to 2-nonanone emitted by Bacillus sp. BCT9

Volatile organic compounds (VOCs) released from bacterial species have been reported as plant growth inducers. In this sense, Lactuca sativa was used as model vegetable to prospect the effects of 2-nonanone released by Bacillus sp. BCT9 at cellular and organ structure level, so we present preliminary results about the physiological effects. In this study, 2-day-old L. sativa were exposed to 2-nonanone for 10 days under two delivery systems: 1) 2-nonanone (abrupt delivery) and 2) 2-nonanone + lanolin (controlled delivery). The X-ray elemental microanalysis, scanning electron and confocal laser microscopies techniques were used to evaluate physiological changes “in vivo” conditions. The results indicated that 2-nonanone increased root and shoot length independently of 2-nonanone delivery system after 7 days of exposition. Additionally, 2-nonanone elicited the increase of anthocyanin and not affects chlorophyll content and electrolyte leakage percentage. The abrupt delivery elicited the increase of both length and density of root hair without causing changes in size of cell epidermis, while controlled delivery induced stomatal opening. Besides, 2-nonanone exposition did not modify the composition and distribution of carbon, nitrogen, phosphorus, potassium, and chlorine in the surface of plant tissue. The results suggested that 2-nonanone acts as a bacterial signal molecule to elicit changes related to root development without damaging the external morphology while epidermal cells at leaf level are not affected, suggesting that 2-nonanone can be an important tool to apply to vegetables.

Layered gadolinium hydroxides for simultaneous drug delivery and imaging.

The potential of the layered gadolinium hydroxide (LGdH) [Gd2(OH)5]Cl·yH2O (LGdH-Cl) for simultaneous drug delivery and magnetic resonance imaging was explored in this work. Three non-steroidal anti-inflammatory drugs (diclofenac [dic], ibuprofen [ibu], and naproxen [nap]) were intercalated into LGdH-Cl for the first time, using three different routes (ion exchange intercalation, coprecipitation, and exfoliation-self-assembly). X-ray diffraction, elemental microanalysis and IR spectroscopy confirmed successful incorporation of the drug into the interlayer spaces of the LGdH in all cases. From a comparison of the guest anion sizes and interlayer spacings, the active ingredients are believed to adopt intertwined bilayer configurations between the LGdH layers. The materials prepared by coprecipitation in general have noticeably higher drug loadings than those produced by ion exchange or self-assembly, as a result of the incorporation of some neutral drug into the composites. The LGdH-drug intercalates are stable at neutral pH, but rapidly degrade in acidic conditions to free Gd3+ into solution. While LGdH-nap releases its drug loading into solution very rapidly (within ca. 1.5 h) at pH 7.4, LGdH-dic shows sustained release over 4 h, and LGdH-ibu extends this to 24 h. The latter composites therefore can be incorporated into enteric-coated tablets to provide sustained release in the small intestine. The drug intercalates are highly biocompatible and retain the proton relaxivity properties of the parent LGdH-Cl, with the materials most promising for use as negative contrast agents in MRI. Overall, the LGdH-drug intercalation compounds appear to have great potential for use in theranostic applications.

The Validity of Nano-chitosan/ Nano-Hydroxyapatite as a Promoter of Bone Healing in Ovariectomized Rats

Background: Nano-hydroxyapatite (nHA) is a biomaterial successfully used in bone tissue engineering. As well, Nano-chitosan (nCTS) is one of the natural polymers used in tissue engineering research. The unique properties of nCTS/nHA composite materials have attracted research interest especially in bioapplications. Estrogen deficiency is responsible for osteoporosis which is a metabolic bone disease characterized by delayed bone healing.Aim of study: to investigate the putative effect of nCTS/nHA combination on the healing of bony defects in experimental postmenopausal hypoestrogenic rat model.Materials and Methods: Forty eight, 6 month old, virgin female rats were randomly allocated into four equal groups; ovariectomy (OVX), Sham, OVX- nCTS/nHA treated, and Sham- nCTS/nHA treated groups. Sixty days following OVX or Sham surgery, a critical-sized defect on the right side of mandible was created in all groups then filled with nCTS/nHA hydrogel only in the third and fourth groups. Two and four weeks following bony defect surgery, six animals per group were euthanized and bone samples were processed for light microscopic (LM) examination, X-ray elemental microanalysis and scanning electron microscopic (SEM) examination.Results: LM and SEM examinations of OVX group revealed delayed bone healing during both experimental periods in comparison with other groups. Interestingly, application of nCTS/nHA revealed improvement in bone healing process. X-ray elemental microanalysis of OVX group depicted marked significant decrease in calcium level below those of other groups. However, using nCTS/nHA revealed significant increase in calcium level suggesting its augmenting role in bone mineralization.Conclusion: Estrogen deficiency impaired bone healing process. However, the synergistic effect of nCTS / nHA has the ability to improve the impaired bone healing in rats with OVX-induced osteoporosis.Key words: Nano-hydroxyapatite, Nano-chitosan, Ovariectomy, Estrogen deficiency, Bone healingAbbreviations: nHA: Nano-hydroxyapatite; nCTS: Nano-chitosan; OVX: ovariectomy; LM: light microscope; SEM; scanning electron microscope.

Hydroxy double salts loaded with bioactive ions: Synthesis, intercalation mechanisms, and functional performance

The intercalation of the anions of diclofenac (Dic), naproxen (Nap), and valproic acid (Val) into three hydroxy double salts (HDSs) has been explored in this work. Experiments were performed with [Co1.2Zn3.8(OH)8](NO3)2·2H2O (CoZn-NO3), [Ni2Zn3(OH)8](NO3)2·2H2O (NiZn-NO3) and [Zn5(OH)8](NO3)2·2H2O (Zn-NO3). It proved possible to intercalate diclofenac and naproxen into all three HDSs. In contrast, Val could be intercalated into CoZn-NO3 but when it was reacted with Zn-NO3 the HDS structure was destroyed, and the product comprised ZnO. Successful intercalation was verified by X-ray diffraction, IR spectroscopy, and elemental microanalysis. Molecular dynamics simulations showed the Dic and Nap ions to arrange themselves in an “X” shape in the interlayer space, forming a bilayer. Val was found to adopt a position with its aliphatic groups parallel to the HDS layer, again in a bilayer. In situ time resolved X-ray diffraction experiments revealed that intercalation of Dic and Nap into CoZn-NO3 and Zn-NO3 is mechanistically complex, with a number of intermediate phases observed. In contrast, the intercalation of all three guests into NiZn-NO3 and of Val into CoZn-NO3 are simple one step reactions proceeding directly from the starting material to the product. The HDS-drug composites were found to have sustained release profiles.

Mode of heparin attachment to nanocrystalline hydroxyapatite affects its interaction with bone morphogenetic protein-2.

Heparin has a high affinity for bone morphogenetic protein-2 (BMP-2), which is a key growth factor in bone regeneration. The aim of this study was to investigate how the rate of release of BMP-2 was affected when adsorbed to nanosized hydroxyapatite (HAP) particles functionalized with heparin by different methods. Heparin was attached to the surface of HAP, either via adsorption or covalent coupling, via a 3-aminopropyltriethoxysilane (APTES) layer. The chemical composition of the particles was evaluated using X-ray photoelectron spectroscopy and elemental microanalysis, revealing that the heparin grafting densities achieved were dependent on the curing temperature used in the fabrication of APTES-modified HAP. Comparable amounts of heparin were attached via both covalent coupling and adsorption to the APTES-modified particles, but characterization of the particle surfaces by zeta potential and Brunauer-Emmett-Teller measurements indicated that the conformation of the heparin on the surface was dependent on the method of attachment, which in turn affected the stability of heparin on the surface. The release of BMP-2 from the particles after 7 days in phosphate-buffered saline found that 31% of the loaded BMP-2 was released from the APTES-modified particles with heparin covalently attached, compared to 16% from the APTES-modified particles with the heparin adsorbed. Moreover, when heparin was adsorbed onto pure HAP, it was found that the BMP-2 released after 7 days was 5% (similar to that from unmodified HAP). This illustrates that by altering the mode of attachment of heparin to HAP the release profile and total release of BMP-2 can be manipulated. Importantly, the BMP-2 released from all the heparin particle types was found by the SMAD 1/5/8 phosphorylation assay to be biologically active.

Regulation of 2,4-epibrassinolide on mineral nutrient uptake and ion distribution in Ca(NO3)2 stressed cucumber plants

2,4-Epibrassinolide (EBL) is a plant hormone that plays a pivotal role in regulation of plants growth and development processes under abiotic stress. The investigation was carried out to study the effect of EBL on mineral nutrients uptake and distribution with ion element analysis and X-ray microanalysis in cucumber seedlings (Cucumis sativus L. cv. Jinyou No.4) under 80mM Ca(NO3)2 stress. Our study found EBL significantly alleviated the inhibitory of P, K, Na, Mg, Fe, Mn, or Cl uptake in shoot or root by Ca(NO3)2 stress. Under Ca(NO3)2 stress, X-ray microanalysis showed that high levels of Ca by EBL treatment accumulated in the epidermal cells of root and gradually decreased from epidermal cells to stellar parenchyma. K+ levels were restored in different cross section of roots and high K+ level mostly accumulated in stellar parenchyma. The results of Ca2+ ultra-structural localization showed Ca2+ particles of antimonite precipitate by EBL were partly decreased in mesophyll and root cells, and Ca2+ precipitate distributed in intercellular spaces again. Increased Ca2+-ATPase activity and ATP content by EBL were also contributed to extrude excess Ca2+ from the cytoplasm. These results suggested that EBL could alleviate the ion damage from excess Ca2+ through regulating mineral nutrients uptake and distribution.

Micro-topography and reactivity of implant surfaces: an in vitro study in simulated body fluid (SBF).

The creation of micro-textured dental implant surfaces possessing a stimulating activity represents a challenge in implant dentistry; particularly, the formation of a thin, biologically active, calcium-phosphate layer on their surface could help to strengthen the bond to the surrounding bone. The aim of the present study was to characterize in terms of macrostructure, micro-topography and reactivity in simulated body fluid (SBF), the surface of titanium (Ti) implants blasted with TiO2 particles, acid etched with hydrofluoric acid, and activated with Ca and Mg-containing nanoparticles. Sandblasted and acid-etched implants were analyzed by ESEM-EDX (environmental scanning electron microscope with energy dispersive X-ray system) to study the micromorphology of the surface and to perform elemental X-ray microanalysis (microchemical analyses) and element mapping. ESEM-EDX analyses were performed at time 0 and after a 28-day soaking period in SBF Hank's balanced salt solution (HBSS) following ISO 23317 (implants for surgery—in vitro evaluation for apatite-forming ability of implant materials). Microchemical analyses (weight % and atomic %) and element mapping were carried out to evaluate the relative element content, element distribution, and calcium/phosphorus (Ca/P) atomic ratio. Raman spectroscopy was used to assess the possible presence of impurities due to manufacturing and to investigate the phases formed upon HBSS soaking. Micro-morphological analyses showed a micro-textured, highly rough surface with microgrooves. Microchemical analyses showed compositional differences among the apical, middle, and distal thirds. The micro-Raman analyses of the as-received implant showed the presence of amorphous Ti oxide and traces of anatase, calcite, and a carbonaceous material derived from the decomposition of an organic component of lipidic nature (presumably used as lubricant). A uniform layer of Ca-poor calcium phosphates (CaPs) (Ca/P ratio <1.47) was observed after soaking in HBSS; the detection of the 961 cm⁻¹ Raman band confirms this finding. These implants showed a micro-textured surface supporting the formation of CaPs when immersed in SBF. These properties may likely favor bone anchorage and healing by stimulation of mineralizing cells.

SEM and EDS observations of carrollite bioleaching with a mixed culture of acidophilic bacteria

Bioleaching of high purity carrollite minerals with mesophilic bacteria was carried out and monitored by observations in scanning electron microscopy (SEM) and elemental X-ray microanalysis (EDS) to provide evidence of the interaction pattern between carrollite and microorganisms. A bacterial consortium involving three different acidophilic chemolithotrophs was adopted. The evolution of the surface topography, inside alteration effects and elemental composition of the mineral with leaching time was followed. It could be postulated that bacterial adhesion takes place on the mineral surface, resulting in the formation of dissolution pits of various shapes and continues by boring elongated channels deep inside the mineral grains. Enhanced concentration of ferric iron and sulphur could be assumed in vicinity of the zones where mineralized polymer substances are precipitated. It could be inferred that carrollite dissolution is governed by cooperative bioleaching involving oxidation induced by bacteria attached to the surface and ferric iron re-oxidized by planktonic bacteria in suspension.

Ordered mesoporous V2O5/WO3composite catalysts for efficient oxidation of aryl alcohols

Multicomponent mesoporous metal oxides show promise in the area of heterogeneous catalysis due to the synergetic interactions between the framework components and the high internal surface area. In this study, we present the synthesis of ordered mesoporous tungsten(VI) oxide–vanadium oxide (V2O5) nanocomposite frameworks via a two-step wet chemical deposition and nanocasting process and demonstrate that they exhibit high catalytic activity and stability for the oxidation of aryl alcohols, using tert-butyl hydroperoxide (t-BuOOH) as oxidant. X-ray diffraction, transmission electron microscopy and nitrogen porosimetry results indicate that the template-free materials possess a 3D mesoscopic structure of discernible domains of parallel-arranged nanorods and have an internal pore surface with narrow mesopores. The chemical composition and molecular structure of the mesoporous matrix were determined with elemental X-ray microanalysis (EDS), diffuse reflectance ultraviolet-visible (UV-vis) and Raman spectroscopy. Our catalytic results indicate that a small addition of V2O5 into the lattice of WO3 has a beneficial effect on the catalytic performance. Thus, the 4% V2O5-loaded WO3 catalyst shows a large improvement in the oxidation of various para-substituted aryl alcohols with respect to the pure mesoporous WO3, giving good-to-high yields (ca. 80–100%) of the target products within 1–4 h reaction time.