Energy Dispersive X-ray Measurements Research Articles

Remotely Controlled Surface Charge Modulation of Magnetoelectric Nanogenerators for Swift and Efficient Drug Delivery.

We have developed a highly efficient technique of magnetically controlled swift loading and release of doxorubicin (DOX) drug using a magnetoelectric nanogenerator (MENG). Core-shell nanostructured MENG with a magnetostrictive core and piezoelectric shell act as field-responsive nanocarriers and possess the capability of field-triggered drug release in a cancerous environment. MENGs generate a surface electric dipole when subjected to a magnetic field due to the strain-mediated magnetoelectric effect. The capability of directional magnetic field-assisted modulation of the surface electrical dipole of MENG provides a mechanism to create/break ionic bonds with DOX molecules, which facilitates efficient drug attachment and on-demand swift detachment of the drug at a targeted site. The magnetic field-assisted drug-loading mechanism was minutely analyzed using spectrophotometry and Raman spectroscopy. The detailed time-dependent analysis of controlled drug release by the MENG under unidirectional and rotating magnetic field excitation was conducted using field-emission scanning electron microscopy, energy-dispersive X-ray, and atomic force microscopic measurements. In vitro, experiments validate the cytocompatibility and magnetically assisted on-demand and swift DOX drug delivery by the MENG near MCF-7 breast cancer cells, which results in a significant enhancement of cancer cell killing efficiency. A state-of-the-art experiment was performed to visualize the nanoscale magnetoelectric effect of MENG using off-axis electron holography under Lorentz conditions.

Development of suitable magnetite–diatomite nanocomposite for Cd (II) adsorptive removal from wastewater

A magnetite-diatomite nanocomposite (MDM) adsorbent was synthesized using the co-precipitation method, wherein a magnetite precursor was intercalated into diatomite clay minerals sourced from the Ethiopian Rift Valley. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy energy dispersive x-ray (SEM-EDX), Brunauer-Emmett-Teller (BET) and magnetometry measurements were used to look into the structure and magnetic properties of the adsorbent. Batch experiments were conducted to study the remarkable Cd (II) adsorption capacity of MDM and the ease of separating the used adsorbent with a bar magnet. The most important adsorption parameters, namely, initial pH, adsorbent dose (g), initial (Cd (II) concentration (mg), and contact time (min), were optimized using Box-Behnken design (BBD). The MDM has shown exceptional Cd (II) removal under optimum conditions, with a maximum adsorption capacity of 31.4 mg/g from aqueous solution. Based on the results of isotherm and kinetic studies, the Temkin and pseudo-second-order models were found to provide the most accurate fit for adsorption equilibrium when compared to the alternative models. The thermodynamic studies, under standard conditions revealed that, Cd (II) uptake is exothermic and spontaneous. The finding of this study confirms that the MDM adsorbent is easily reusable, extractable from the solution using an external magnet, and capable of recovering around 80 % of Cd (II) when HNO3 is used as a desorbing agent. The study demonstrates a cost-effective and environmentally friendly approach to remediate Cd (II) pollution in wastewater. Furthermore, the superior Cd (II) adsorption capacity, combined with the ease of separating using a bar magnet and high reusability, highlights the potential of this novel adsorbent as a sustainable and efficient solution for addressing Cd (II) contamination in various wastewater treatment applications.Thereby contributing significantly to advancements in the field of heavy metal removal from aqueous solutions.

In-situ failure behavior and interfacial bonding of an interpenetrating metal matrix composite reinforced with lattice-like metallic glass (Ni60Nb20Ta20) preform

Metallic glasses (MG) have an amorphous atomic structure and exhibit several exceptional properties such as high strength, hardness associated with high elastic strain limit and elastic energy storage. But MGs are also prone to brittle fracture, making them difficult to use as monolithic structural components and might better be used as a reinforcement phase in hybrid composites such as metal matrix composites (MMC). The failure behavior of composites depends on the structure of the reinforcement phase. In this work, the failure behavior of an interpenetrating MMC reinforced with a MG (Ni60Nb20Ta20) lattice-like preform and AlSi12-matrix was investigated by in-situ compression tests under scanning electron microscopy to get a better understanding of the influence of the lattice-like preform and mechanical interference between both phases. Additionally, microstructure analysis by scanning transmission electron microscopy and energy dispersive X-ray measurements were carried out to gain insight into the chemical composition of the interfaces. The failure behavior in manufacturing direction of the MMC is dominated by shear stress whereas transversely to manufacturing direction by normal stress and exhibits therefore an anisotropic failure behavior. Investigations of the interfaces show more of a mechanical than chemical bonding but in general a good interfacial bonding was confirmed.

Deciphering the immobilization of lipases on hydrophobic wrinkled silica nanoparticles

In this work, the adsorption of Candida antarctica B (CALB) and Rhizomucor miehei (RML) lipases into hydrophobic wrinkled silica nanoparticles (WSNs) is investigated. WSNs are hydrophobized by chemical vapor deposition. Both proteins are homogeneously distributed inside the pores of the nanoparticles, as confirmed by Transmission Electron Microscopy and Energy Dispersive X-ray measurements. The maximum enzyme load of CALB is twice that obtained for RML. Fourier Transform Infrared Spectroscopy confirms the preservation of the enzyme secondary structure after immobilization for both enzymes. Adsorption isotherms fit to a Langmuir model, resulting in a binding constant (KL) for RML 4.5-fold higher than that for CALB, indicating stronger binding for the former. Kinetic analysis reveals a positive correlation between enzyme load and RML activity unlike CALB where activity decreases along the enzyme load increases. Immobilization allows for enhancing the thermal stability of both lipases. Finally, CALB outperforms RML in the hydrolysis of ethyl-3-hydroxybutyrate. However, immobilized CALB yielded 20 % less 3-HBA than free lipase, while immobilized RML increases 3-fold the 3-HBA yield when compared with the free enzyme. The improved performance of immobilized RML can be explained due to the interfacial hyperactivation undergone by this lipase when immobilized on the superhydrophobic surface of WSNs.

Preparation, spectroscopic and anticancer investigations of metal-drug complexes associated between flumequine antibiotic drug with lanthanum(III), samarium(III) and terbium(III) chloride

Flumequine ligand (FLQ) metal complexes of the [M(FLQ)2(Cl)(H2O)].nH2O type, where M are (La(III), Sm(III), and Tb(III)) and FLQ is flumequine have been synthesized. The FLQ metal complexes could be prepared using MCl3 : flumequine in stoichiometry of 1:2 in situ bidentate chelation. The characterization of FLQ complexes obtained have been done using elemental analyses (%C, %H and %N), molar conductivity (Ʌm), infrared spectroscopy (FTIR), electronic spectra (UV-Vis), thermal analysis (TGA), and physicochemical techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) measurements at room temperature. Accordingly, these complexes are indicative of an octahedral coordination structure. Flumequine ligand has a bidentate fashion through the oxygen atoms of carbonyl (quinolone) and carboxylic groups. The findings demonstrated the anti-cancer efficacy of these compounds against HepG-2 and MCF-7 cancer cell lines at extremely low doses of up to 58.2 mg/mL. The La(III) complex was shown to have the highest selectivity against cancer cells in comparable with both samarium and terbium(III) complexes.
 KEY WORDS: Flumequine, Lanthanide metal ions, FTIR, EDX, Complexation, Anticancer activity
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 671-684. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.10

Fabrication of superhydrophobic aluminum with enhanced anticorrosive property

The current work mainly introduces a facile method to obtain superhydrophobic aluminum with a hierarchical micro-nanostructure by a combination strategy of anodizing, chemical etching, and surface modification using SiO2@PDMS coating via a simple chemical vapor deposition (CVD) method. Scanning electron microscopy (SEM), energy dispersive X-ray (EDS), EDS-mapping, X-ray diffraction (XRD) and water contact angle (WCA) measurements have been performed to characterize the surface morphology, chemical composition, phase structure, and wetting property of the surfaces, respectively. The SEM results showed that by anodizing a network of cylindrical nanoporous is formed. By etching, the diameter of these pores increases and surface modification using CVD causes the deposition of SiO2@PDMS nanoparticles over them. The WCA measurements showed that the samples of the anodized and anodized-etched aluminum after modifying with SiO2@PDMS nanoparticles become superhydrophobic with values of 153° and 154°, respectively. The corrosion resistance of samples was analyzed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results displayed that the charge transfer resistance of the superhydrophobic surface of modified anodized-etched aluminum is 16700 kΩ cm2, which is 900 times higher than that of pure aluminum. Also, the positive shift of 0.385 V in corrosion potential and reduction of more than 3 orders of magnitude in corrosion current are observed compared with aluminum. All results show a significant improvement in the corrosion protection of Al due to anodizing and surface modification with superhydrophobic coating. This method is suggested as a simple technique to creating aluminum with superhydrophobic surfaces in industry.

Identification of structural and optical properties and adsorption performance of (Cd0.4Ni0.4Mn0.2)Fe2-xRuxO4 nanoparticles for the removal of Congo red dye

In the field of industrial wastewater treatment, the application of highly efficient methods such as adsorption is crucial for effectively eliminating dangerous pollutants before effluent discharge. Ferrite nanoparticles (NPs) have emerged as promising candidates for the efficient and sustainable removal of dyes from wastewater. Therefore, the synthesis, characterization, and application of (Cd0.4Ni0.4Mn0.2)Fe2-xRuxO4 (0 ≤ x ≤ 0.04) NPs as adsorbents for the removal of Congo Red (CR) dye, is reported in this study. The X-ray powder diffraction (XRD) analysis has confirmed the purity of the samples with a very small amount of hematite phase. The prepared NPs have pseudo-spherical morphology and average particle size in the range of 12–17 nm. Furthermore, the elemental compositions, estimated from the energy dispersive x-ray (EDX) measurements, indicate the homogenous distribution of elements and the substitution of the Fe3+ host ions by the Ru3+ dopant. As the Ru content increases from 0.00 to 0.04, SBET increases from 52.39 to 78.34 m2/g, respectively. Furthermore, the pore diameter, ranging between 12.71 and 18.38 nm, reveals the mesoporous nature of the prepared samples. The direct and indirect bandgap energy, calculated from UV–vis spectroscopy analysis, is in the range of 3.049–3.232 eV and 1.894–2.642 eV, respectively. The adsorption performance of the prepared NPs for the removal of CR dye solution was investigated by varying the contact time, adsorbent amount, pH, and reaction temperature. The adsorption process follows a second-order kinetic model and the NPs with x = 0.015 revealed the highest adsorption rate with a rate constant k2 = 2.7 × 10−3 g.mg−1.min−1. The optimum experimental conditions, achieved in the presence of 80 mg of (Cd0.4Ni0.4Mn0.2)Fe1.985Ru0.015O4 NPs at 308 K and in the acidic medium at pH = 3.45, result in the removal of 87.5 % of CR dye after 60 min. After applying several non-linear adsorption isotherm models, mainly Langmuir, Freundlich, and Temkin isotherms, the experimental data were well-fitted with the Temkin isotherm model. The strong interactive force between CR and (Cd0.4Ni0.4Mn0.2)Fe1.985Ru0.015O4 nanoparticles is revealed from the high value of bT knowing that bT = 182.91 J.mol−1.

Green Physical Modification of Polypropylene Fabrics by Cross-Linking Chitosan with Tannic Acid and Postmodification by Quaternary Ammonium Grafting to Improve Antibacterial Activity.

A green cross-linking and straightforward method to physically trap inert fibers in a network of chitosan was implemented. The cross-linking reaction involved a biosourced and biocompatible cross-linker [tannic acid (TA)] and mild conditions in water (pH = 8.5, O2 bubbling, 60 °C, 3 h). The steric hindrance of TA led to a low but effective cross-linking rate leaving parts of primary amines of chitosan available for postmodification such as the grafting of quaternary ammoniums for antibacterial purposes. Fabric's coatings were characterized by scanning electron microscopy coupled with energy-dispersive X-ray, infrared spectroscopy, and weight gain measurements. This allowed the optimization of process conditions. No significant antioxidant activity was observed on fabrics coated with chitosan cross-linked with TA, confirming the low cross-linking rate. This low cross-linking rate allowed grafting of quaternary ammoniums for antibacterial purposes, but it is possible to consider grafting other active molecules. Biological assays were conducted on this coating to assess its antibacterial properties. Reduction of bacterial colonization on both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), two of the major strains responsible for nosocomial infections, confirmed the potential of the coating for antibacterial purposes. This study displays a simple and ecofriendly process to coat inert fabrics with a chitosan network containing reactive functions (primary amines) available for grafting active molecules for various purposes.

Novel Pd0.1Cu0.9Co2O4 nano-flake: A promising multifunctional catalyst for the electrochemical water splitting and photo-degradation reactions at ambient temperature

Herein, we report the fabrication of self-assembled Pd0.1Cu0.9Co2O4-nano-flakes via the co-precipitation method. The formation of poly-crystalline cubic spinel phase Pd0.1Cu0.9Co2O4-nano-flake has been identified by powder X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray measurement techniques. The Pd0.1Cu0.9Co2O4 nano-flakes exhibited outstanding activity in the electrochemical water splitting reaction leading to the production of hydrogen and oxygen gas at ambient temperature. Higher current density, lower overpotential, and Tafel slope all are desirable for both HER and OER. Best HER activity (η100 = 628 mV) and capacitive performance in acid was found for Pd-doped electrocatalyst whereas in base the good OER performance (η2 = 434 mV) and capacitive performance was found for CuCo2O4 electrocatalyst. Further, the CPE test demonstrated that Pd0.1Cu0.9Co2O4-nano-flakes are electrochemically stable for 2 h without significant loss in activity. The present catalyst also shows remarkable photocatalytic activity in the degradation of Methylene blue (MB) under visible light at ambient temperature and degrades 100% MB dye in just 1 min. The role of reactive species in the photo-degradation of MB has been established by scavenger tests.

A Microshutter for the Nanofabrication of Plasmonic Metal Alloys with Single Nanoparticle Composition Control.

Alloying offers an increasingly important handle in nanomaterials design in addition to the already widely explored size and geometry of nanostructures of interest. As the key trait, the mixing of elements at the atomic level enables nanomaterials with physical or chemical properties that cannot be obtained by a single element alone, and subtle compositional variations can significantly impact these properties. Alongside the great potential of alloying, the experimental scrutiny of its impact on nanomaterial function is a challenge because the parameter space that encompasses nanostructure size, geometry, chemical composition, and structural atomic-level differences among individuals is vast and requires unrealistically large sample sets if statistically relevant and systematic data are to be obtained. To address this challenge, we have developed a microshutter device for spatially highly resolved physical vapor deposition in the lithography-based fabrication of nanostructured surfaces. As we demonstrate, it enables establishing compositional gradients across a surface with single nanostructure resolution in terms of alloy composition, which subsequently can be probed in a single experiment. As a showcase, we have nanofabricated arrays of AuAg, AuPd, and AgPd alloy nanoparticles with compositions systematically controlled at the level of single particle rows, as verified by energy dispersive X-ray and single particle plasmonic nanospectroscopy measurements, which we also compared to finite-difference time-domain simulations. Finally, motivated by their application in state-of-the-art plasmonic hydrogen sensors, we investigated PdAu alloy gradient arrays for their hydrogen sorption properties. We found distinctly composition-dependent kinetics and hysteresis and revealed a composition-dependent contribution of a single nanoparticle response to the ensemble average, which highlights the importance of alloy composition screening in single experiments with single nanoparticle resolution, as offered by the microshutter nanofabrication approach.

Structural properties and electron spin resonance (ESR) dose estimations of fossil cow tooth enamel from Köşk Höyük, Turkey.

In this work, two cow teeth collected from the Niğde-Köşk Höyük excavation site in Turkey were studied for characterization and dosimetric purposes. Each tooth sample was prepared by applying mechanical and chemical methods to obtain the enamel fractions. To do this, mineralogical and elemental concentration properties of the tooth enamels were investigated by performing X-ray diffraction (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray measurements (SEM-EDX). It was found that the enamel structures contained a highly hydroxyapatite crystalline without any characteristic impurities. The dose response of the tooth enamels was determined by using the electron spin resonance (ESR) method. Absorbed radiation doses were calculated as (26.05 ± 0.15) Gy and (25.48 ± 0.18) Gy by the additive dose method using both natural radiation doses and artificial irradiation doses of the enamel samples. It is concluded that these samples could be used to reconstruct radiation doses. This result can be considered as a precursor for future ESR dosimetry/dating studies of other fossil teeth at this excavation site.

Surface characteristics of fused silica in medium-pressure plasma process

In order to obtain an ultra-smooth fused silica surface without surface damage efficiently, medium-pressure plasma processing has been design and developed. In the medium-pressure plasma polishing process, the stable plasma process of the medium-pressure plasma directly impacts surface roughness. The fluorine (F) atom, which is reactive and provided by SF6, O2, and He gas, is a very significant supplementary gas, and those gases play a significant part in the process. The medium-pressure plasma is used for polishing fused silica, and an optical emission spectrometer is used to observe the deviations in the intensity of atoms, ions, and species during processing. The experiment has been conducted at optimum conditions, i.e., gas composition (He:(SF6 + O2)) of 90:10, pressure ratio (SF6/O2) of 1:1, and RF power of 80 W. The surface roughness of the optical material, i.e., fused silica, has been marginally increased from Ra = 1.95 μm to Ra = 2.02 μm at a total pressure of 5 mbar and RF power of 80 W. Field-emission scanning electron microscopy results show that the morphology has been changed after the plasma process. The initial coarse microstructure of fused silica transforms a finer structure through plasma processing under optimal conditions. Energy-dispersive X-ray (EDX) results reveal that the elements Si and O are present at the surface before processing, and Si, O, F, and C, have been observed after processing. After plasma processing, EDX measurement confirms the presence of fluorine elements, demonstrating the interaction of the plasma with the substrate.

Structural and Optical Properties of Bismuth-doped Cerium Oxide Prepared at a Low Temperature

Cerium oxide (CeO2) is a functional material with excellent physicochemical properties. Its properties can be modified by doping with different elements, including bismuth, which can be done through various synthesis methods. The precipitation method combined with ultrasonic radiation was used to synthesize bismuth-doped cerium oxide (CeO2:Bi) at a low temperature of 200oC. In this study, we investigate the alteration of structural and optical properties of as-prepared CeO2:Bi by subjecting it to additional calcination at a high temperature of 500oC. The structural and optical properties of CeO2:Bi were characterized using thermal gravimetric analysis, X-ray diffraction, Scanning Electron Microscope-Energy Dispersive X-Ray, Fourier Transform Infrared spectroscopy, and UV-Visible spectroscopy. The additional calcination produced a less significant weight-loss percentage than the as-prepared CeO2:Bi observed from the gravimetric curve. The Fourier transform infrared spectrum revealed the loss of a small number of hydroxyl molecules trapped on the CeO2:Bi surface when additional calcination was subjected. Based on the X-ray diffraction spectra, additional calcination results in the smallest crystallite size and compressive strain without the changed cubic crystal structure of CeO2:Bi. The successful doping of Bi in CeO2 was confirmed by the composition analysis from Energy Dispersive X-Ray measurement. Scanning electron microscope image showed spherical and agglomerated particles of calcined CeO2:Bi. The optical properties of both CeO2:Bi possessed similar trend absorption spectra and almost the same band gap energy. The results indicated that the calcination of as-prepared CeO2:Bi at a temperature of 500oC did not affect its structural and optical properties significantly. Thus, combining ultrasonic radiation with precipitation is an advantageous method to synthesize at a low temperature of stable CeO2:Bi crystalline.

Synthesis of Green Cerium Oxide Nanoparticles Using Plant Waste from Colocasia esculenta for Seed Germination of Mung Bean (Vigna radiata)

Synthesis of cerium oxide (CeO2) nanoparticles (NPs) via biological approach has received a lot of interest to reduce the harmful effects of chemical synthesis. In the present study, Colocasia esculenta leaf extract facilitated the preparation of CeO2-NPs by using the sol-gel technique. The crystal structural of CeO2-NPs was proven by X-ray powder diffraction (XRD) investigation to be cubic with size of 2.94 nm according to Debye–Scherrer equation. As demonstrated in the transmission electron microscopy (TEM) image, CeO2-NPs have a spherical form with an average size of 2.04 nm which is almost consistent with a finding from XRD analysis. Energy dispersive X-ray (EDX) measurements exhibited high-intensity peaks attributed to Ce and oxygen and further proved the creation of CeO2-NPs. The Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of Ce-O stretching, indicating the formation of CeO2-NPs. Functional groups of O-H, C-O, and C=O peaks were found in a spectrum due to the phytochemical components that were responsible for reducing and stabilizing during the synthesis process of CeO2-NPs. The examined UV-visible spectra exhibited the absorbance peak at 213 nm. The synthesized NPs produced in this study were further investigated for mung bean seed germination, whereby the influence of grain germination and growth rate demonstrated the significant finding.

Low-Temperature Sintering of Bi(Ni0.5Ti0.5)O3-BiFeO3-Pb(Zr0.5Ti0.5)O3 Ceramics and Their Performance.

A low-temperature sintering strategy was realized for preparing 0.21Bi(Ni0.5Ti0.5)O3-0.05BiFeO3-0.74Pb(Zr0.5Ti0.5)O3 (0.21BNT-0.05BF-0.74PZT) ceramics by conventional ceramic processing by adding low melting point BiFeO3 and additional sintering aid LiBO2. Pure perovskite 0.21BNT-0.05BF-0.74PZT ceramics are prepared at relatively low sintering temperatures, and their structure presents tetragonal distortion that is affected slightly by the sintering temperature. The 1030 °C sintered samples have high densification accompanied by relatively large grains. All ceramics have excellent dielectric performance with a relatively high temperature of dielectric constant maximum, and present an apparent relaxation characteristic. A narrow sintering temperature range exists in the 0.21BNT-0.05BF-0.74PZT system, and the 1030 °C sintered 0.21BNT-0.05BF-0.74PZT ceramics exhibit overall excellent electrical performance. The high-temperature conductivity can be attributed to the oxygen vacancies' conduction produced by the evaporation of Pb and Bi during sintering revealed by energy dispersive X-ray measurement.

CuI as a Hole-Selective Contact for GaAs Solar Cells

Carrier-selective contacts have emerged as a promising architecture for solar cell fabrication. In this report, the first hole-selective III-V semiconductor solar cell is demonstrated using copper iodide (CuI) on i-GaAs. Surface passivation quality of GaAs is found to be essential for open-circuit voltage (VOC), with good correlation between photoluminescence properties of the GaAs layer and the VOC. Passivation with <10 nm thick In0.49Ga0.51P layers is shown to provide an over 300 mV improvement. Oxygen-rich CuI is formed by natural oxidation in the atmosphere, and the increased oxygen content of ∼10% is validated by energy-dispersive X-ray measurements. The oxygen incorporation is shown to improve hole selectivity and thus solar conversion efficiency. Ultraviolet photoelectron spectroscopy indicates a high work function of ∼6 eV for the oxygen-rich CuI. With optimized GaAs surface passivation and oxygen-rich CuI, a VOC of nearly 1 V and a solar conversion efficiency of 13.4% are achieved. The solar cell structure includes only undoped GaAs, a surface passivation layer, and non-epitaxial CuI contact and is therefore very promising to various low-cost crystal growth methods. The results have a significant impact on III-V solar cell fabrication and costs as it (i) enables fully carrier-selective architectures, (ii) reduces cell fabrication complexity, and (iii) is suitable for layers grown by low-cost crystal growth techniques.

Membrane fouling in thermophilic aerobic membrane distillation bioreactor treating hospital wastewater

In the membrane distillation bioreactor (MDBR) process, flux increases with increasing feed temperature, but the presence of microorganisms limits the feed temperature. Also, the accumulation of cells and other substances on the membrane surface can affect the efficiency of MDBR. In this study, hospital wastewater was treated by thermophilic activated sludge MDBR. In the MDBR, the initial flux was 7.87 L‧m−2·h−1 and the stable flux was 3.88 L‧m−2·h−1. The particle size, zeta potential and hydrophobicity of the activated sludge in MDBR were 2.25 µm, −14 mV and 24%, respectively. In addition, EPS (extracellular polymeric substances) and SMP (soluble microbial products), having a significant effect on membrane fouling, were determined to be 201.50 mg·L−1 and 669.35 mg·L−1 in MDBR, respectively. Contact angle, FTIR (Fourier transform infrared), SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy) measurements were also made on a virgin membrane and used membrane. Analysis of EDX, SEM and F-TIR showed that the membrane fouling was caused by CaCO3 and EPS.

Nitrate adsorption characteristics of synthesized allophanes with various chemical compositions

AbstractAllophane-related aluminium silicates with various chemical compositions were synthesized using a hydrothermal reaction with inorganic reagents as starting solutions. The X-ray diffraction traces of the synthesized allophanes showed broad reflections centred at 0.34 and 0.23 nm, which were attributed to the imogolite-like structure of the allophanes. Energy-dispersive X-ray measurements confirmed that the Al-rich materials were synthesized as targeted. The specific surface area of the synthesized allophanes was 313–500 m2 g–1, which is greater than that of a natural allophane (248 m2 g–1). The amount of nitrate adsorbed on the synthesized allophanes tended to increase as the Al content increased. The maximum amount of nitrate adsorbed was 2.07 mmol g–1 at pH ~2, which was comparable to that of a common anion-exchange material. A possible adsorption mechanism for nitrate at lower pH levels is the weak NO3– interaction of the positively charged surface of Al-OH2+ sites.

Electrical and microstructural evaluation of ZnO varistor ceramics with different CaSiO3 contents

In the present study, the impact of CaSiO3 addition on microstructure and electrical characteristics of a ZnO-based varistor system was investigated. The ceramic materials were prepared by solid-state reaction route by varying the CaSiO3 concentrations (0, 3, 6, 9, 12, and 15 wt%) and sintered at 1300 °C. Characterization of the pelletized samples was carried out by density measurement, scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, and current density-electric field characteristics measurement. The growth of ZnO grain was restrained with the introduction of CaSiO3; the average grain size decreases from 18.09 to 10.85 μm, whereas their relative density increases up to 99.79%. Structural results indicated the existence of the CaSiO3-rich phase without any other secondary phase formation. It is also revealed that different CaSiO3 contents significantly affect the electrical properties, prominently in the sample with 12 wt% CaSiO3 addition. The maximal value of the nonlinear coefficient, breakdown voltage, and barrier height acquired in this work were 4.41, 0.80 V/mm, and 0.691 eV, respectively, along with a sharp decline in leakage current density to 373.93 μA/cm2. Further increase in CaSiO3 content (15 wt%) eventually caused a deterioration in varistor behavior.

Use of Raman Spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy in a Multi-Technique Approach for Physical Characterization of Purple Urine Bag Syndrome

Purple urine bag syndrome (PUBS) is a rare condition characterized by purple discoloration of urine and urine bags. Although it is benign, it represents an alarming symptom to the patients and their relatives because of purple discoloration. We have physically characterized urine and urine bags belonging to a patient suffering from PUBS using an approach that combines Raman spectroscopy (RS) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX). Five “blue” discolored bags and one sterile urine bag, representing the control, were cut into 1 cm2 square samples and analyzed by using RS and SEM + EDX technique. RS enabled us to identify the presence of indigo, a metabolite of tryptophan, while SEM analysis showed the biofilm deposit, probably due to the presence of microorganisms, and the EDX measurements exhibited the elemental composition of the bags. In particular, urine bags before and after the presence of PUBS urine showed an increase of ~32% of Cl, ~33% of O, ~667% of Ca, ~65% of Al and Mg, while C decreased by about 41%. Our results, to be taken as a proof-of-principle study, are promising for the aim to characterizing the urine bags in a flexible, inexpensive, and comprehensive manner.