Different Techniques For Characterization Research Articles

One Step Superparamagnetic Iron Oxide Nanoparticles by a Microwave Process: Optimization of Microwave Parameters with an Experimental Design

AbstractSuperparamagnetic iron oxide nanoparticles (SPIONs) are nanoparticles used in a lot of applications such as batteries, and biomedical, … To obtain these nanoparticles, several techniques exist such as coprecipitation, thermal decomposition, sol–gel process but they have some advantages (synthesis in a water media, high crystallinity, high monodispersity) and disadvantages (using an organic solvent, large distribution of size, poor crystallinity). The goal of this work is to synthesize SPIONs for biomedical applications (for example as a contrast agent for the MRI): SPIONs should be stable in an aqueous media, monodisperse, and have good crystallinity and magnetic properties. To achieve this result, a microwave process is carried out. However, any study describes the microwave parameter on the synthesis of the nanoparticles. This work offers to determine the best conditions of the microwave to obtain ideal SPIONs for MRI. For this, an experimental design is carried out to determine these parameters thanks to different techniques of characterization (Transmission Electronic Microscopy, Dynamic Light Scattering, X‐ray diffraction, Thermogravimetric Analysis, magnetic characterizations). With the different results of these characterizations, the best conditions of the microwave are determined, and a simulation of all experiments is realized with a surface response.

Electrochemical impedance spectroscopy evaluation of nonthermal plasma restoration for ductile metals in cultural heritage artifacts

AbstractDespite the large number of studies devoted to understanding the degradation process of ductile metals in cultural heritage, there is still a lack of consolidated protocols for their restoration. Traditional restorations such as chemical cleaning and electrochemical treatments are carried out for the recovery of corroded ductile metals. However, these techniques are usually very aggressive to the metallic surface. For this reason, a cold plasma design is presented to restore ductile metals through the minimum intervention criterion. Lead samples were induced to atmospheric acetic acid corrosion to recreate models of degradation for practical restoration and characterization. The material after plasma treatment was analyzed with different techniques of characterization, including electrochemical impedance spectroscopy. The present work demonstrated the potential of this technique to provide an accurate analysis of its surface.

The Formation of Doped PZT Solid Solution and Its Structural Characterization

The main objective of this work is the synthesis, structural and morphological characterization of ceramics materials. Abbreviated PZT-PYN. Ferroelectric ceramics of general formulation Pb(ZrxTi1-x)O3 are massively used in many fields such as medicine or aeronautics because of their dielectric and electromechanical properties, although the electronic properties of doped PZT are much better compared to undoped PZT. Samples selected for this study were prepared bins solid way. The thermal treatment called calcination was applied to these compositions is carried around: 450℃, 550℃, 650℃, 750℃, and 900℃ for two hours with a Vitesse of 2℃ / min., then sintered at different temperatures: 1100℃, 1150℃, 1180℃, successively to optimize the sintering temperature where the product is better physical quality. Different techniques of characterization were used such as scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and Energy-dispersive spectrometric, which showed that the response is optimal for the compositions included in the morphotropic phase boundary, achieves excellent properties.

Impact of TiO2 on physical, optical, and radiation shielding properties of tungsten-based glasses

The melt-quenching route was applied to prepare phosphate glasses of the system 20Na2O–(50-x)Na2WO4–30P2O5: xTiO2 with 0 ≤ x ≤ 25 mol%. These glasses are characterized by different techniques of characterization to determine the role of TiO2 in the physical-optical parameters of the synthesized glasses. The experimental data showed that as TiO2 content increased, the density values decreased from 4.58 ± 0.01 g cm−3 to 3.20 ± 0.01 g cm−3. Some metrics, including the optical band gap (Eg) and Urbach energy (ΔE), have been assessed using optical techniques. Eg decreases from 2.92 eV to 1.73 eV and ΔE grew from 0.41 eV to 0.64 eV as these parameters evolved in the opposite manner. Depending on the placement of TiO2 in glasses, this change is connected to the creation of non-bridging oxygens. Additionally, other parameters are determined by the UV-Visible absorption, and an increase in TiO2 mol percent causes a decrease in optical basicity (Ath), electronic polarizability (αO2-), optical electronegativity (χ*), and the electronic polarizability (αe), respectively, from 0.9244 to 0.8877 eV, from 1.9976 eV to 1.9670 eV, from 0.8064 eV to 0.7634 eV. Furthermore, as non–bridging oxygens increase, the refractive index (n) increases from 2.419 to 2.863, the dielectric constant (ɛ) increases from 5.851 to 8.196, and the optical dielectric constant (p(dp/dt)) increases from 4.851 to 7.196. It is discovered that the transmission coefficient and reflection loss are antiproportional.

Synthesis and physicochemical characterization of new calcined layered double hydroxide Mg Zn Co Al-CO3; classical modeling and statistical physics of nitrate adsorption

This research focuses on the study of a new material, a layered double hydroxide, which was synthesized using a co-precipitation method at pH constant and, then, tested for its retention of nitrate anions. The LDH was prepared from four metal cations Mg-Zn-Co-Al to produce the quadratic material mentioned, Mg Zn Co Al-CO3, which was calcined to obtain metal oxides. Different techniques of characterization were considered, namely FTIR, X-ray diffraction, BET, SEM and EDX. Adsorption experiments for nitrate were carried out to test the effect of contact time, adsorbent mass, pH values, mass effect, and initial surfactant concentrations. When equilibrium was reached after 300 min (R2 = 0.998), the Pseudo-second order model was found to fit accurately the kinetic data. The intraparticle diffusion model recorded a rate constant of between 0.277 and 0.757 (g/mg. min−0.5) and the Sips adsorption isotherm best fitted the experimental data obtained. Maximum adsorption capacity for nitrate was found to be 55.97 mg g−1 which was in accordance with the experimental results. Thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic. The values of ΔH˚ and ΔS˚ of the adsorption process were 14.81 and 59.04 kJ mol−1, respectively. The low value of ΔH˚ (<40 kJ mol−1) indicated that the adsorption process was associated with physical forces. Finally, for a deeper insight into the nitrate adsorption mechanism, the statistical physics model was considered to quantify the number of adsorbed nitrate molecules per site, the anchorage number, the receptor sites density, the adsorbed quantity at saturation, the concentration at half saturation and the molar adsorption energy. A statistical physics model, with two binding sites, proved to be the best option to characterize and interpret the removal of nitrate on the tested LDH.

Oxygen vacancies and defects tailored microstructural, optical and electrochemical properties of Gd doped CeO2 nanocrystalline thin films

In this study, the authors present a pure and Gadolinium (Gd) doped CeO2 nanostructures, successfully elaborated onto the glass and Indium Tin Oxide (ITO) coated glass substrates under optimized parameters. A spray pyrolysis method was used at a temperature of 450 °C, with simultaneous incorporation of Gd at various concentrations (0, 2, 4, 6, 8 at. %) as a dopant. Different techniques for characterization were used to study the Gd impact on the microstructural, the morphological, the optical and the electrochemical behaviors of the CeO2 material. The XRD patterns shows that Gd3+ ions are inserted at the Ce4+ ion sites in the cubic fluorite structure network of CeO2 nanocrystals (NCs). Raman spectroscopy and UV–Vis–NIR have been utilized to study the defect structure and optical behaviors in these NCs. Broadening and Peak asymmetry of Raman active mode are attributed to the existence of Ce3+ and oxygen vacancy, which have been changed with addition of Gd3+ ions in CeO2 NCs. The results of UV–Vis–NIR spectroscopy show the variations of the optical gap energy with fluencies of Gd3+ due to the variations of particles sizes of NCs. Cyclic voltammetry results show that the ion storage capacities (ISC) of CeO2 thin films are increased with Gd doping. This research paper reports on the fluencies of Gd doping in CeO2 nanocrystals, to understand the role of oxygen vacancies and the impact they have on the tailoring of the microstructural, optical and electrochemical behaviors of doped CeO2 nanocrystals for multiple applications such as, catalysts, oxygen transportation, ultraviolet fuel cells, and electrochromic devices etc.

Optimizing the Biosorption Behavior of Ludwigia stolonifera in the Removal of Lead and Chromium Metal Ions from Synthetic Wastewater

In this study, a natural low-coast, efficient, and eco- bio-sorbent plant material (Ludwigia stolonifera), with both parts of the root and shoot, were studied for the removal of the cationic metal ions, lead Pb2+ and chromium Cr6+, via batch mode experiments to evaluate their maximum adsorption capacity, and held a comparison between the used bio-sorbent roots and shoots, based on the highest bio-sorption potential. Optimization of the bio-sorption parameters, such as contact time, pH, bio-sorbent (root and shoot) dosage, and initial ion concentration was conducted. The results indicated that 1.6 g of the used bio-sorbent shoot material removed 81.4% of Pb2+, and 77% of Cr6+ metal ions from liquid media under the conditions of 100 ppm of initial metal ions concentration at room temperature for 60 min of contact time with the static condition. Different isotherms and kinetic models were fit to the experimental data to understand the nature of the bio-sorption process. The experimental data were best fit by the pseudo-second-order kinetic model with a high correlation coefficient (R2 = 0.999), which reveals the chemisorption nature of the bio-sorption process. The chemical and structural analysis of the used bio-sorbent, before and after Cr6+ and Pb2+ bio-sorption, were performed using different techniques of characterization, such as Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The used bio-sorbent proved to be a low-cost, efficient, and eco-friendly material to remove heavy metal ions from aqueous solutions.

Grado de avance de la tesis “Deformación plástica severa para el desarrollo de microestructura de grano ultrafino en aleaciones de titanio para uso industrial”

En este trabajo se muestra el grado de avance de la tesis doctoral "Deformación plástica severa para el desarrollo de microestructura de grano ultrafino en aleaciones de Titanio para uso industrial” cuyo objetivo general es determinar y comparar rutas de fabricación, deformación y tratamiento térmico de aleaciones de Ti que faciliten el desarrollo de una estructura de granos ultrafinos con posibilidades de escalamiento industrial. Para tal fin se proponen técnicas como laminación asimétrica, deformación de chapa por corte en canal angular, manufactura aditiva y una adecuada combinación de ellas y/o tratamientos térmicos posteriores. En el marco de esta tesis se utilizan además diferentes técnicas de caracterización para estudiar los diferentes caminos de deformación que hacen posible, en definitiva, el desarrollo de granos de tamaño micronanométrico.

Ab-initio, Monte Carlo and experimental investigation on structural, electronic and magnetic properties of Zn1-xNixO nanoparticles prepared via sol-gel method

In this work, structural, electronic and magnetic properties of Ni doped ZnO nanoparticles (NP’s) synthesized via the sol-gel method have been investigated. Different techniques of characterization have been applied to study the Ni dependence of the microstructural, morphological, compositional and magnetic properties. As a result, X-ray diffraction analysis indicates that the obtained samples have a hexagonal Wurtzite structure with preferential orientation along (101). The increase of Ni concentration leads to a size reduction of the nanoparticles. Also segregated Ni clusters have been observed by SEM/EDX. The magnetization field (M − H) curves reveal the existence of ferromagnetism in Ni-doped ZnO at room temperature. First principle calculations based on density functional theory are applied to study the effect of Ni doping on the structural, electronic and magnetic properties of ZnO, allowing for a deeper understanding for the experimental findings. The obtained results indicate that Ni doped ZnO with less than 8.33% Ni present long-range ferromagnetic ordering. Furthermore, Ni doped ZnO is antiferromagnetically stable at 12.5%. Monte Carlo simulation based on heat bath algorithm coupled with DFT results have been used to validate the proposed explanation for the magnetic behavior of the experimental part. Therefore, the obtained results indicate that Ni doped ZnO is a good candidate as a diluted magnetic semiconductor due to its high exchange coupling interaction that leads to a high Curie temperature.

Studies of the adsorption kinetics process for removal of methylene blue dye by residue of grenadine bark extraction

This study makes it possible to prove that an inexpensive material, namely the residue of grenadine bark extraction (GB), can be used to remove a dye from the textile industry, in particular methylene blue (MB). For this reason, different techniques of characterization of the GB adsorbent have been used such as: scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the zero charge point. On the other hand, batch studies have been used to evaluate the effect of initial concentration, contact time, adsorbent dose, pH and temperature on the variation in uptake capacity. In this case, the results show that a very fast adsorption kinetics reaching 98% within the first 10 minutes. Additionally, kinetic studies of dye on MB carried out the pseudo-second order at different dye concentration values. Besides, the Langmuir model describes satisfactory adsorption on the GB. Further, thermodynamic studies have indicated that dye adsorption process by grenadine bark (GB) was spontaneous, physisorption and endothermic in naturel

Fast adsorption for removal of methylene blue from aqueuous solutions using of local clay

In the present work we are interested in the study of the adsorption of a methylene blue cationic dye (BM) on natural material such as local clay (CM). For this reason, we carried out a parametric study of adsorption by studying the effect of several important parameters on the decolorizing power of the material used, in particular: contact time, adsorbent concentration, adsorbent dose, pH and temperature. A kinetic study was performed and kinetic models were applied to experimental results such as pseudo first order and pseudo second order. A modeling of the isotherms was carried out by applying known models such as Langmuir and Freundlich. The decolorization percentage was 92 %. Kinetic studies of dye on MB carried out the pseudo-second order at different dye concentration values. The Langmuir model describes satisfactory adsorption on the CM. Thermodynamic studies indicated that dye adsorption process by CM was spontaneous and endothermic in nature. On the other hand, different techniques of characterization of the CM adsorbent were used such as: scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).

SHARAR'S NOVEL DILCHASP: ONE PENNY TOO MANY

Colonial predicament made the life and its understanding complex in the Subcontinent. To represent this complexity, Urdu writers found the polyphonic genre, i.e. the novel helpful. They used different techniques of characterization to narrate the social hierarchy of characters. The novel also provided the space for them to attract the people with encapsulating the residual sensibility of conventional love of Urdu poetry and at the same time launch their ideas of reform to accommodate the changing world. This article presents an analysis of Sharar's Dilchasp and argues that he used the novelistic genre to represent his hierarchized social milieu, cultural norms and reformative agenda.

Activation energies and structural changes in carbon nanotubes during different acid treatments

In this work, we studied the effect of acid type in the final properties of CNTs as the resistance to air oxidation; for this, different techniques of characterization were used such as Raman spectroscopy, thermogravimetric analysis, and chemical analysis by ICP-AES. Through Raman spectroscopy, it is possible to monitor the structural changes induced by acids and this is reflected in changing of the activation energies for the different processes determined by thermogravimetric analysis; also by ICP-AES analysis, it was shown that the inorganic material was eliminated efficiently with the acid treatments used in this study.

Phosphotungstates as catalysts for monoterpenes oxidation: Homo- and heterogeneous performance

Lacunary (PW11), mono-substituted (PW11M) and sandwich type M4(PW9)2 phosphotungstates (M=CoII, FeIII) exhibits high catalytic activity for geraniol and R-(+)-limonene oxidation under mild conditions, using hydrogen peroxide as oxidant and acetonitrile as solvent. The best homogeneous performance was found for the PW11 and for the Co4(PW9)2. Complete conversion of geraniol and R-(+)-limonene was achieved after 1.5h and 3h of reaction, respectively, when catalyzed by PW11. The yield of 2,3-epoxygeraniol was 100% in the presence of lacunary PW11 and mono-substituted compounds. PW11 and Co4(PW9)2 were immobilized on an amine-functionalized SBA-15 (aptesSBA-15) and the composites materials were characterized by FT-IR, FT-Raman, UV–vis/DRS, 31P MAS NMR, elemental analysis and SEM-EDS. Their heterogeneous catalytic activity was investigated for the same substrates and compared with that in homogeneous conditions. The PW11@aptesSBA-15 and Co4(PW9)2@aptesSBA-15 showed to be active heterogeneous catalysts for geraniol epoxidation with 100% of selectivity for 2,3-epoxide. R-(+)-limonene was also oxidized by PW11@aptesSBA-15 achieving 90% of conversion after 24h of reaction. Both composites could be separated after the reaction and reused for at least three cycles without loss of activity. The stability of the heterogeneous catalysts after catalytic reactions was investigated by different techniques of characterization.

The Effect of Plasma Chemistry on the Damage Induced to Porous SiCOH Dielectrics

The scope of this study was to compare the plasma damage produced on porous dielectrics by different chemistries under identical plasma conditions and evaluate different techniques for characterization of the damage. We have investigated the effects of , , and plasmas on the properties of three porous SiCOH dielectrics. All plasma treatments have been performed in the same plasma tool under identical conditions. The plasma treatment caused modifications to the bonding structure of the films, loss of film thickness, and increase in refractive index and dielectric constant that varied with plasma and among the films. Fourier transform infrared spectroscopy indicated the type of structural modification caused by a certain plasma treatment but could not be used to predict the damage to the dielectric constant. No correlation was observed between the shrinkage of the film and the corresponding increase of its dielectric constant. The increases of the dielectric constant correlated only to the increases of refractive index after the plasma treatments. The largest damages to the dielectric constants were caused by plasma treatments at room temperature. The most damaging to the porous SiCOH films was the plasma, while the overall lowest damage was produced by the plasma at .

Postsynthesis modification of a cellulose acetate ultrafiltration membrane for applications in water and wastewater treatment

AbstractA technique for postsynthesis modification of a cellulose acetate ultrafiltration membrane with possible application in water and wastewater treatment is studied. The technique used an oxidizing agent (persulfate) to develop free radicals on the membrane surface, and that was expected to promote grafting of hydrophilic macromolecules (polyethylene glycol). A chain‐transfer agent (2‐mercaptoethanol) was tested to control the grafting process, avoiding the formation of long chains that usually lead to high permeability losses in other graft techniques. The modifications aimed at the decrease of the fouling susceptibility of the membrane studied. The possibility of an increase in rejection was also investigated. The membrane was characterized before and after modification, by attenuated total reflectance–Fourier transform‐infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and in terms of the rejection of neutral reference solutes. The information given by the different techniques of characterization provided strong evidences of the occurrence of modification, although permeation of (real) foulants was the decisive test. To obtain information about the fouling tendency of the nonmodified and modified membranes, two different kinds of foulants were used: a humic acid (usually found in surface waters) and textile auxiliaries (representing one of the most important industries in Portugal). The results showed an increase in the rejections of the humic acid, and significant improvements in the performance of the membrane with respect to fouling tendency in the case of the textile auxiliaries. © 2005 American Institute of Chemical Engineers Environ Prog, 2005

Revisiting sodium and water reabsorption with functional genomics tools.

The kidney plays an essential role in maintaining sodium and water balance, thereby controlling the volume and osmolarity of the extracellular body fluids, the blood volume and the blood pressure. The final adjustment of sodium and water reabsorption in the kidney takes place in cells of the distal part of the nephron in which a set of apical and basolateral transporters participate in vectorial sodium and water transport from the tubular lumen to the interstitium and, finally, to the general circulation. According to a current model, the activity and/or cell-surface expression of these transporters is/are under the control of a gene network composed of the hormonally regulated, as well as constitutively expressed, genes. It is proposed that this gene network may include new candidate genes for salt- and water-losing syndromes and for salt-sensitive hypertension. A new generation of functional genomics techniques have recently been applied to the characterization of this gene network. The purpose of this review is to summarize these studies and to discuss the potential of the different techniques for characterization of the renal transcriptome. Recently, DNA microarrays and serial analysis of gene expression have been applied to characterize the kidney transcriptome in different in-vivo and in-vitro models. In these studies, a set of new interesting genes potentially involved in the regulation of sodium and water reabsorption by the kidney have been identified and are currently under detailed investigation. Characterization of the kidney transcriptome is greatly expanding our knowledge of the gene networks involved in multiple kidney functions, including the maintenance of sodium and water homeostasis.

Role of the surface roughness in laser induced crystallization of nanostructured silicon films

The crystallization of hydrogenated nanostructured silicon (ns-Si:H) films deposited from Ar-silane mixture in a low-pressure pulsed radio-frequency glow discharge has been studied in relation with their structural and morphological properties. Different techniques of characterization converge to the fact that both the porosity and the surface roughness of the film increase with the plasma duration (Ton) used for the deposition. The correlation between the film structure and the crystallization threshold has been investigated. The modifications of the bulk structure of the film with Ton partly explain the decrease of the crystallization threshold (Ecryst). The role of the surface roughness in the lowering of the crystallization threshold is emphasized. Its contribution is interpreted by the enhancement of the electromagnetic field at the ns-Si:H film surface.

Particle sizing and biokinetics of interstitiallymphoscintigraphic agents

The biokinetics of inert lymphoscintigraphic agents strongly depends on their particle size. Different techniques for characterization of colloids are discussed. Experiments have been performed on eight different colloids. The particle size has been investigated with scanning electron microscopy. Activity distributions have been obtained with ultrafiltration and gel-column scanning technique. The colloids suggested for lymphoscintigraphy were found to have a median size of about 40-50 nm except one minimicro-aggregated human serum albumin colloid which has a median particle size around 10 nm. The biokinetics were studied with a scintillation camera in rabbits after a subcutaneous injection. Time-activity curves were generated. After 5 hr the rabbits were dissected and the activity content in different tissues measured. A compartment model for the biokinetics was designed and rate constants evaluated. The total and specific activity uptake in parasternal lymph nodes was highest for the small-particle colloids. The compartment model showed a good fitting to the experimental data.

Physical methods used for the characterization of modes of epitaxial growth from the vapor phase

The three modes of epitaxial growth from the vapor phase known from theory are experimentally illustrated with examples. Special emphasis is placed on the usefulness of the different techniques of characterization of the growth mechanisms: (a) Frank - van der Merwe layer-by-layer growth; (b) Volmer-Weber three-dimensional growth mode; (c) Stranski-Krastanov intermediate growth mode. In the study of epitaxy, RHEED, AES, and TEM are suitable tools in most of the cases, but other methods such as ellipsometry and desorption kinetics in various circumstances, appear very promising.