Energy Dispersive X-ray Spectrometer Analysis Research Articles

Temperature dependent deformation behavior and texture evolution in AA6082 aluminum alloy: An integrated experimental and crystal plasticity simulation approach

This research provides a comprehensive analysis of the texture and temperature dependent deformation behavior of the aluminum alloy AA6082. The study is performed using a combination of experimental deformation tests and computational simulations using a crystal plasticity (CP) framework. The primary objective is to identify the critical influence of temperature on local stress states and dislocation density within the material during tensile tests. From an experimental perspective, the study employs ex-situ deformation tests and subsequent electron backscatter diffraction (EBSD) data in combination with energy dispersive x-ray spectrometer (EDS) analysis at 200 °C and 400 °C. The experimental EBSD data are adopted, preprocessed and converted into a geometry file for the numerical simulations. On the computational front, a dislocation density-based material model is adopted for CP simulations. The physical and fitting parameters of the model are calculated, adopted from the literature, or calibrated by comparing the global simulation results with experimental stress-strain observations under uniaxial tensile load at room temperature, 200 °C and 400 °C. Empirical functions for solid solution strengthening, dislocation density, fitting parameters controlling mean free path and dislocation annihilation have been derived that can be used to quickly interpolate them for any intermediate temperature. These functions combined with other model parameters can now be used for temperature-dependent CP modeling of AA6082. The isothermal grain-scale simulation and ex-situ experimental results confirmed a noteworthy texture transformation at higher temperatures, characterized by a reduction in the primary Cube orientation and its transition into a Copper orientation due to the stretching process. The correlation between the experimental results and the simulations on macro- and micro-scales is reasonable, indicating the accuracy and effectiveness of the CP approach in predicting the temperature dependent deformation behavior and texture evolution in aluminum alloys.

The analysis of long-time-exposed tars from wood shingles from church roofs and facades in mid-Sweden

ABSTRACT Poor condition of roofs in terms of decay of shingles and loss of tar-based surface treatments has been revealed in a number of churches at various geographical locations in mid-Sweden. The condition of tars obtained from shingles of selected churches in mid-Sweden were analysed and obtained data were compared with geographical locations of the churches. According to gas chromatography-mass spectroscopy result, dehydroabietic acid was the dominant compound found in the exposed tars from the churches except in church of Malung where similar amounts of retene was found. Oxidised resin acids were found in exposed tars from the churches but not in commercially available pit burned tar. Tar from church shingles had higher char residues than the pit burned tar which was totally consumed when heated under nitrogen gas up to 750°C using thermogravimetric analysis. Scanning electron microscopy with energy dispersive X-ray spectrometer analysis revealed higher amounts of silicates in some exposed tars; however, these compounds constituted only a minor portion of the organic matter in these specimens. Based on the data obtained in the study other factors rather than simply geographical location of churches seemed to be of importance to explain differences of the investigated properties of the church tars.

Mechanical octacalcium phosphate coatings on the plasma electrolytic oxidized pure titanium for bio-implant use

In this study, OCP powder was used for mechanical coating on the plasma electrolytic oxidized (PEO) implant surface to improve bioactivity. PEO treatment was performed on the surface of the implant using a solution mixed with calcium acetate and calcium glycerophosphate, and creates porosity through a pulsed DC power supply. For compositional analysis, energy dispersive X-ray spectrometer analysis was employed to calculate OCP content and X-ray diffractometer analysis was used to confirm the crystal structure. Also, wettability, surface roughness, hardness, elastic modulus, and corrosion resistance testing were performed. Significantly, the reduction in OCP particle size decreased, and pore filling with OCP smaller particles increased as mechanical coating time increased from 0 to 12 h. Surface and cross-sectional morphology showed the presence of OCP on the substrate. Also, surface roughness, contact angles, hardness, and elastic modulus were reduced as mechanical coating time increased. Corrosion resistance was found to be the highest for mechanical OCP coating for 6 h surface treatment on the PEO-treated CW-Ti.

Enhancing La(III) biosorption and biomineralization with Micromonospora saelicesensis: Involvement of phosphorus and formation of monazite nano-minerals

The release of rare earth elements (REEs) from mining wastes and their applications has significant environmental implications, necessitating the development of effective prevention and reclamation strategies. The mobility of REEs in groundwater due to microorganisms has garnered considerable attention. In this study, a La(III) resistant actinobacterium, Micromonospora saelicesensis KLBMP 9669, was isolated from REE enrichment soil in GuiZhou, China, and evaluated for its ability to adsorb and biomineralize La(III). The findings demonstrated that M. saelicesensis KLBMP 9669 immobilized La(III) through the physical and chemical interactions, with immobilization being influenced by the initial La(III) concentration, biomass, and pH. The adsorption kinetics followed a pseudo-second-order rate model, and the adsorption isotherm conformed to the Langmuir model. La(III) adsorption capacity of this strain was 90 mg/g, and removal rate was 94 %. Scanning electron microscope (SEM) coupled with energy dispersive X-ray spectrometer (EDS) analysis revealed the coexistence of La(III) with C, N, O, and P. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) investigations further indicated that carboxyl, amino, carbonyl, and phosphate groups on the mycelial surface may participate in lanthanum adsorption. Transmission electron microscopy (TEM) revealed that La(III) accumulation throughout the M. saelicesensis KLBMP 9669, with some granular deposits on the mycelial surface. Selected area electron diffraction (SAED) confirmed the presence of LaPO4 crystals on the M. saelicesensis KLBMP 9669 biomass after a prolonged period of La(III) accumulation. This post-sorption nano-crystallization on the M. saelicesensis KLBMP 9669 mycelial surface is expected to play a crucial role in limiting the bioimmobilization of REEs in geological repositories.

Anhydrous sol-gel synthesis of TiO2 nanoparticles: Evaluating their impact on protein interactions in biological systems

This study focused on the synthesis of anhydrous sol-gel synthesis of TiO2 nanoparticles using a hydrothermal route. The chemical properties of the synthesized TiO2 nanoparticles were confirmed through Fourier Transform Infrared Spectroscopy (FT-IR) and UV–Vis spectroscopy, highlighting their optical features. Additionally, Energy Dispersive X-ray Spectrometer (EDX) analysis revealed the high purity of the nanomaterial, while the Transmission Electron Microscope (TEM) displayed spherical particles ranging in size from ≥ 80 nm. Furthermore, X-ray diffraction analysis (XRD), Raman and HRTEM analyses indicated that the nanomaterial exhibits an anatase and rutile structure. When, Hen Egg-White Lysozyme (HEWL) incubated with TiO2 led to notable changes: reduced fluorescence indicating protein unfolding, increased light scattering showing protein aggregation, the presence of amyloid fibrils and hydrophobic regions, and reduced enzyme activity. FTIR spectroscopy revealed amyloid structure formation, while Dynamic Light Scattering confirmed the presence of larger protein oligomers. These findings highlight TiO2's adverse impact on HEWL structure and function, emphasizing the need for further research on nanoparticle toxicity in biological systems, particularly in biomedical applications.

The Liquid Fraction of ZA27 Zinc Alloy from TLP Diffusion Bonding Affecting Mechanical Properties and Microstructural Characterizations of SSC-ADC12 Aluminum Alloy

This work investigated liquid fraction in ZA27 zinc alloy interlayered with SSC-ADC12 aluminum alloy workpieces for Transient Liquid Phase (TLP) diffusion bonding. The results clearly indicated that liquid fraction had a necessary influence on TLP diffusion bonding. In other words, the high liquid fraction and bonding time tends to produce excellent bond strength. The maximum bond strength at 27.21 MPa was from 100% liquid fraction and 90 min from bonding time. The hardness increased by approximately 23.36% comparing to SSC-ADC12 aluminum alloy and by 11.18% comparing to the ZA27 zinc alloy. The microstructure was homogeneous in the bond line and formed to MgZn2 and CuZn4 intermetallic compound under Scanning Electron Microscope. According to Energy Dispersive X-Ray Spectrometer analysis, Zn atoms had the ability to move about 4.381 mm from the bond line and the elements' uniform distribution.

Surface Characterization, Mechanical Properties, and Corrosion Behavior of Zn-Ni Alloy Coated Steel Using Electroplating-Hot-Dip Galvanizing

In this study, the processing of zinc-nickel alloys with an electroplated nickel layer as the first layer followed by hot-dip galvanizing on plain carbon steel (St37) is investigated. The effect of the nickel layer and the effect of the immersion time on the alloy layers of the coating obtained by this method are studied. In addition, some properties of the obtained coating, such as the overall thickness, hardness, surface uniformity, coating adhesion strength, and corrosion resistance, were investigated using the optical microscope, scanning electron microscopy, energy dispersive x-ray spectrometer analysis, and potentiostat. The results show that the 16-min immersion time is the optimum galvanizing time at which an alloy with a nickel content of 0.11 wt% is formed and that the overall thickness of the galvanized sheet, especially the alloy layers, decreases compared to the pure zinc sheet. In addition, a more ductile, corrosion-resistant, and smoother surface is obtained.

Rock Magnetic and Mineralogical Properties of Lateritic Soil Profiles Developed on Two Different Parent Rocks in Northern Kerala, South-Western India

The rock magnetic and mineralogical properties of two lateritic soil profiles developed on two different parent rocks (khondalite and granite) in northern Kerala, south-western India were investigated to better understand pedogenic processes under tropical climate. Field investigations reveal the presence of various horizons in the lateritic profiles, such as saprolite, mottled zone, pebble horizon and top soil. The particle size, rock magnetic, Vibrating Sample Magnetometer (VSM), Scanning Electron Microscopy (SEM)-Energy-Dispersive X-ray Spectrometer (EDS) and X-Ray Diffraction (XRD) analyses were performed on samples collected from different horizons of the two profiles. Magnetic susceptibility (χlf) values of the lateritic profiles vary from 9.97 to 1717.04 x 10-8 m3 kg-1, with the granitic profile exhibiting overall higher values. The percentage frequency-dependent susceptibility (χ %) ranges between 0 % and 13.9 %. The XRD data reveal the presence of kaolinite, gibbsite (except for top soil layer) and quartz along with magnetic minerals like magnetite, hematite and goethite. The upper horizons (top-soil and pebble horizon) exhibit high values for concentration dependent magnetic parameters like χlf and χfd%, whereas, the lower horizons (saprock, saprolite, pallid zone horizons) exhibit low values. The tropical soils in the region have undergone a higher degree of pedogenesis with increased magnetic mineral concentration compared to temperate soils. The magnetic enhancement in the topsoil may be due to the neoformation of ultra fine-grained SP magnetite/maghemite (with minor anti-ferro magnetic component), aided by sufficient Fe supply, alternate wetting and drying cycles, dehydration, oxidation and redox conditions. Keywords: Lateritic Soils; Soil Magnetism; XRD; SEM; Magnetic Enhancement; Pedogenesis; Southern India

Study of Streptococcus mutans in Early Biofilms at the Surfaces of Various Dental Composite Resins.

Biofilm deposit on the composite restoration is a common phenomenon and bacterial growth follows the deposition. The study aims to evaluate Streptococcus mutans (S. mutans) early biofilm formation on the surfaces of various dental composite resins by using the real-time quantitative polymerase chain reaction (qPCR) technique. Thirty-two discs, where eight discs were in each group of Filtek Supreme Ultra (FSU; 3M, St. Paul, MN), Clearfil AP-X (APX; Kuraray Noritake Dental Inc., Tokyo, Japan), Beautifil II (BE2; Shofu, Inc., Kyoto, Japan), and Estelite Sigma Quick (ESQ; Tokuyama Dental, Tokyo, Japan), were fabricated and subjected to S. mutans biofilm formation in an oral biofilm reactor for 12 hours. Contact angles (CA) were measured on the freshly fabricated specimen. The attached biofilms underwent fluorescent microscopy (FM). S. mutans from biofilms were analyzed using a qPCR technique. Surface roughness (Sa) measurements were taken before and after biofilm formation. Scanning electron microscopy (SEM), including energy dispersive X-ray spectrometer (EDS) analysis, was also performed for detecting relative elements on biofilms. The study showed that FSUdemonstrated the lowest CA while APXpresented the highest values. FMrevealed that condensed biofilm clusters were most on FSU. The qPCR results indicated the highest S. mutans DNA copies in the biofilm were on FSU while BE2was the lowest (p < 0.05). Sa test signified that APX was significantly the lowest among all materials while FSU was the highest (p < 0.05). SEM displayed areas with apparently glucan-free S. mutans more on BE2 compared to APX and ESQ, while FSU had the least. Small white particles detected predominantly on the biofilms of BE2 appeared to be Si, Al, and F extruded from the resin. Differences in early biofilm formation onto various composite resins are dependent on the differences in materialcompositions and their surface properties. BE2 showed the lowest quantity of biofilm accumulation compared to other resin composites (APX, ESQ, and FSU). This could be attributed to BE2 proprieties as a giomer and fluoride content.

Green synthesis of antimony sulphide (Sb2S3) nano-rods in plant oils and study of photocatalytic activity

This study reports the green synthesis of antimony sulphide (Sb2S3) nano-rods synthesized by thermolysis of antimony diethyldithiocarbamate (Sb [S2CNEt2]) complex as a single source precursor in various plants oils acting as capping agents through their carboxylic acid functionality. The reported method reflects a facile and single-step fabrication of antimony sulphide nanorods and reveales their orthorhombic stibinite phase characterized by p-XRD. The quantification of energy dispersive X-ray spectrometric (EDS) analysis depicted an atomic ratio of approximately 2:3 for Sb: S. The morphology of nano-rods was confirmed by scanning electron microscopy (SEM) analysis and crystallize size was observed ranging 8.09–8.27 nm. The band gap calculated from absorption spectra was found to be 1.93 eV to 2.01 eV for all studied samples. The photocatalytic efficiency of synthesized nanorods evaluated by photocatalysis of Janus Green and Rose Bengal showed the dye degradation up to 99.9% in the presence of biosynthesized catalysts at different times.

The effect of copper on phase transformation, microstructure and mechanical characterization of Ni50-xTi50Cuxshape-memory alloy

This research is related to the investigation of the influence of copper additions on phase transformation, microstructure and mechanical characterization of equiatomic NiTi shape-memory alloys. A typical vacuum arc melting furnace was used in the preparation of Ni50-xTi50Cux(x = 2, 5, 10, and 15 at.%) shape-memory alloys. The crystalline phase formation and phase transformation temperature were studied using X-ray diffraction and a differential scanning calorimeter. The morphology and chemical composition of the annealed samples were investigated using a field emission scanning electron microscope and energy-dispersive X-ray spectrometer analysis. The Vickers microhardness test was utilized in the analysis of the homogeneity of the alloy. The experimental results obtained from X-ray diffraction confirmed the coexistence of austenite and martensite phases along with the presence of a Ti2Ni and minor rutile phases. The crystalline sizes of the alloys were in the range of 42 to 78nm. An energy-dispersive spectrometer validated the distinct phases and precipitates in the alloys. The size and dispersion of the secondary phase in the alloy showed a significant influence on the increased hardness from 407HV to 470HV. The following NiTiCu alloy compositions were employed for low-temperature applications since their transition temperatures were below 100°C.

Preparation of an environmentally friendly demulsifier using waste rice husk as raw materials for oil–water emulsion separation

Demulsification of crude oil emulsions still face many difficulties in the petroleum industry. Therefore, it is very important to develop innovative materials to achieve the effective separation of oil–water emulsions. In this work, an environmentally friendly RHC-0.5 demulsifier was prepared via a simple one-step hydrothermal route using rice husk (RH) as raw materials. It was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy dispersive X-ray spectrometer and thermogravimetric analysis. The possible breaking mechanism was analyzed by particle size analysis, Zeta potential, interfacial activity, interfacial tension, self-assemble of interfacial film and microscopic analysis. The influence of some important factors such as dosage, temperature, standing time and salinity on the demulsifying efficiency (DP) was explored through bottle tests. The optimal DP of 95.01 % could be obtain with 300 mg/L of RHC-0.5 at 70 °C for 10 min. Meanwhile, RHC-0.5 had a good salt tolerance even at the salinity of 40000 mg /L. In addition, its DP was compared with that of commercial demulsifiers such as SP169, CH-66 and AR-32. This work not only can promote the efficient utilization of biological waste (RH), but also provides an insight into the exploration of new demulsifying materials with excellent performance.

Improved frequency response of the 3.5 GHz SMR devices using Ga-doped AlN thin films as the piezoelectric layers

In this paper, the aluminum nitride (AlN) and gallium-doped aluminum nitride (AlGaN) films are adopted to fabricate the 3.5 GHz solidly mounted resonator (SMR) devices. A reactive radio frequency (RF) magnetron sputtering system and a co-puttering subsystem were used to deposit AlN and AlGaN thin films as piezoelectric layers. The sputtering parameters were fixed as sputtering pressure of 35 mTorr and sputtering power of 200 W for AlN piezoelectric layers. For the co-sputtering parameters, the sputtering pressure was set 10 mTorr, and the sputtering powers of Al and GaN targets were 175 W and 25 W, respectively, to deposit AlGaN piezoelectric layers. The X-ray diffraction (XRD) patterns showed that as compared with the 2[Formula: see text] values of the diffraction peaks of AlN thin films, those of AlGaN thin films shifted to lower values. Even the diffraction intensity of (002) peak of AlGaN thin film was higher than that of AlN film, both AlN and AlGaN thin films presented the strongly [Formula: see text]-axis orientated crystallization. The energy dispersive X-ray spectrometer (EDS) analysis showed that the content of Ga element in the AlGaN thin film, ([Formula: see text]), was about 19%. SEM images showed that the obtained AlN and AlGaN thin films exhibited uniform grain sizes and smooth surfaces. Finally, both the frequency responses of the fabricated SMR devices were measured using a network analyzer and the difference in their efficiencies were well compared. The frequency response of the fabricated SMR device with [Formula: see text][Formula: see text]N thin film showed the center frequency of 3.51 GHz, the return loss [Formula: see text] of −10.466 dB, quality factor [Formula: see text] of 170.952, electromechanical coupling coefficient [Formula: see text] of 4.026%, and FoM value of 6.838, respectively. The results show that the frequency response of SMR device has been improved by Ga doped in AlN thin film, although the [Formula: see text] value is still less than that of obtained using single crystalline AlGaN thin film.

Effect of two-step annealing on photoelectrochemical properties of hydrothermally prepared Ti-doped Fe2O3 films

Hematite (α-Fe2O3, bandgap ~2.1 eV) is a potential photoanode candidate for photoelectrochemical water splitting. In this work, we report the preparation of Fe2O3 with Ti4+ doping by hydrothermal treatment at 393 K and then annealing in the air at 873 K, with a second round of annealing in argon at 473 K. The two-step annealing process increased the photoelectrochemical performance of Ti-doped Fe2O3 on a fluorine-doped tin oxide (FTO)-coated glass substrate (FTO/Ti-Fe2O3) for water oxidation in 0.1 mol L−1 NaOH solution. Ti4+ doping was sourced from TiCl4 in ethanol solutions of various concentrations. An energy-dispersive X-ray spectrometer (EDS) analysis confirmed that the optimized Ti/Fe atomic ratio in the solution was ~3%, which showed the highest photocurrent densities in the linear sweep voltammetry and chronoamperometry measurements. The two-step annealed FTO/Ti-Fe2O3 generated a photocurrent density of 0.55 mA cm−2 at 1.50 V vs. reversible hydrogen electrode (RHE) under simulated one-sun illumination, which was approximately 3 times higher than that of the photoanodes annealed in air. Four-point probe resistivity measurements revealed that the two-step annealing resulted in a higher electrical conductivity than that of the samples annealed in air. The conductivity improvements induced by additional argon annealing at 473 K were ascribed to the increased donor density, which was confirmed by Mott–Schottky analysis and diffuse reflectance UV–visible–near-infrared spectra. We found that the strategy of Ti4+ doping and two-step annealing helped fabricate Fe2O3-based photoanode materials with better photocurrent density attributed to high electrical conductivity successfully.

Equilibrium Phase Relations for a SiO2-Al2O3-FeOx System at 1300 °C and 1400 °C in Air

A long-term fundamental study for the construction of the thermodynamic database of a metallurgical slag system has been proposed. In the present work, the equilibrium phase relations for the key ternary SiO2-Al2O3-FeOx system at 1300 °C and 1400 °C in air were experimentally determined by the equilibrium-quenching technique, followed by X-ray Photoelectron Spectroscopy and Scanning Electron Microscope equipped with an Energy Dispersive X-ray Spectrometer analysis. The oxidation states of Fe2O3 and Fe3O4 were confirmed at 1300 °C and 1400 °C, respectively, from both XPS detection and FactSage calculation. Within the high-SiO2 composition range, the solid phases of silica, mullite, magnetite and ferric oxide were confirmed as the equilibrium phases. Based on the equilibrium compositions, the 1300 °C and 1400 °C isotherms were projected onto a SiO2-Al2O3-FeOx quasi-ternary phase diagram; however, obvious discrepancies with about a 20 °C difference were confirmed from further comparison with the predictions given by FactSage, indicating that more efforts are needed for the updating of the current thermodynamic database relating to metallurgical slag oxide systems.

Soils and spoils: mineralogy and geochemistry of mining and processing wastes from lead and zinc mining at the Gratz Mine, Owen County, Kentucky.

Mineralogical and geochemical features of mining and processing wastes collected in Owen County, part of the Central Kentucky Lead-Zinc district, were investigated. The Gratz mine, abandoned in the 1940s, is on a dairy farm. Aside from discerning the nature of mining refuse at the site, the investigation was part of the University of Kentucky College of Pharmacy's mission to explore unusual environments in the search for unique microbiological communities. Four samples of a soil-plus-spoils mix were collected from spoil piles and two samples, the sluice and coarse samples, were closely associated with the site of the ore processing. Optical petrology (polarized reflected-light, oil-immersion optics at a final magnification of 500 ×), X-ray diffraction, X-ray fluorescence, inductively coupled plasma mass spectrometry, field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscope (HR-TEM) with selected area electron diffraction (SAED) and/or microbeam diffraction (MBD), scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectrometer (EDS) analyses were employed to characterize the samples. Calcite is the main mineral in most samples, followed by near equal amounts of quartz and dolomite. Sphalerite and galena are the principal sulfides and barite is the dominant sulfate. Geochemistry of major elements reflected the mineralogy, whereas trace elements showed different groupings between the minerals. Scandium, Cu, Ga, Ge, Cd, and Sb were found predominantly associated with Zn and Pb and sulfide minerals; Bi, Hf, In, Sn, and Zr with heavy mineral fraction; while the remaining trace elements, including the rare earths, were mostly distributed among other present phases, i.e., oxyhalides, oxides, silicates, and carbonaceous material. The data were used to illustrate the processes and conditions that control the sulfide-mineral oxidation and its potential for the environmental release of associated reaction products. The wastes represent a potential source of environmentally disruptive concentrations of Zn, Pb, and other sulfide-associated elements. The high share of carbonates suggests near-neutral conditions in deposited wastes, restricting sulfide weathering and further limiting the oxidant activity of Fe. The low-Fe content and its predominant presence in highly resistant hematite also constrain sulfide weathering. Consequently, the spoils have a low potential for generation of acidity and release of heavy metal(loid)s in the surrounding environment.

Neoformation of palygorskite in Calcids of Central Iran

Palygorskite has been reported in alluvial sediments and in soil clays in Central Iran, but it is not known if it is inherited or formed in situ. Here, we sampled Calcids developed from Triassic and Cambrian dolomitic formations in the southwestern part of Yazd and performed soil and clay characterization by X-ray diffraction and fluorescence, optical and scanning electron microscopy and energy dispersive X-ray spectrometer analyses. Our results suggested palygorskite neoformation in the calcic soil horizons in Calcids. The soils with aridic soil moisture regime and high Mg concentration, during the formation of a calcic horizon by precipitation of secondary calcite, conditions were suitable for authigenic palygorskite crystals of long size (&gt;10–20 μm) and their stability. In addition, the occurrence of short-size (about 2 μm) palygorskite fibers in the lower gypsic horizon probably resulted from its translocation from the upper horizons. Therefore, such results suggested palygorskite neoformation in the calcic soil horizons in these Calcids of Iran.

Fabrication of a 3.5-GHz Solidly Mounted Resonator by Using an AlScN Piezoelectric Thin Film

In this study, a 3.5-GHz solidly mounted resonator (SMR) was developed by doping scandium in aluminum nitride to form AlScN as the piezoelectric thin film. Molybdenum (Mo) of 449 nm thickness and silicon dioxide (SiO2) of 371 nm thickness were used as the high and low acoustic impedance films, respectively, which were alternately stacked on a silicon substrate to form a Bragg reflector. Then, an alloy target with atomic ratio of 15% Sc was adopted to deposit the piezoelectric AlScN thin film on the Bragg reflector, using a radio frequency magnetron sputtering system. The characteristics of the c-axis orientation of the AlScN thin films were optimized by adjusting sputtering parameters as sputtering power of 250 W, sputtering pressure of 20 mTorr, nitrogen gas ratio of 20%, and substrate temperature of 300 °C. Finally, a metal top electrode was coated to form a resonator. The X-ray diffraction (XRD) analysis showed that the diffraction peak angles of the AlScN film shifted towards lower angles in each crystal phase, compared to those of AlN film. The energy dispersive X-ray spectrometer (EDX) analysis showed that the percentage of scandium atom in the film is about 4.5%, regardless of the sputtering conditions. The fabricated resonator exhibited a resonance frequency of 3.46 GHz, which was a small deviation from the preset resonance frequency of 3.5 GHz. The insertion loss of −10.92 dB and the electromechanical coupling coefficient of 2.24% were obtained. As compared to the AlN-based device, the AlScN-based resonator exhibited an improved electromechanical coupling coefficient by about two times.

Development of a novel direct dental pulp-capping material using 4-META/MMA-TBB resin with nano hydroxyapatite

In the case of dental pulp exposure, direct pulp capping is often performed to preserve vital dental pulp tissue. Numerous studies regarding the development of direct pulp-capping materials have been conducted, but materials with an appropriate sealing ability, which induce dense reparative dentin formation, have not been developed. Although nano hydroxyapatite (naHAp) is a bone-filling material with bioactivity and biocompatibility, the inductive effects of naHAp on reparative dentin formation remain unclear. In the present study, the effects of dental adhesive material 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate tri-n-butylborane [4-META/MMA-TBB or Super-bond (SB)], which included 10%, 30%, and 50% naHAp (naHAp/SB) on odontoblastic differentiation of dental pulp stem cells (DPSCs) and reparative dentin formation were investigated. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer analysis were performed to verify the existence of naHAp particles on the surface of naHAp/SB discs. The tensile adhesive strength of naHAp/SB was measured using a universal testing machine. As a result, 10% naHAp/SB and 30% naHAp/SB showed almost the same tensile adhesive strength as SB but 50% naHAp/SB showed significantly lower than the other experimental group. WST-1 proliferation assay and SEM analysis revealed that naHAp/SB did not affect the proliferation of DPSCs. Calcium release assay, quantitative RT-PCR, and western blotting analysis demonstrated that naHAp/SB did not release calcium ion but 30% naHAp/SB increased the expression of calcium-sensing receptor (CaSR) in DPSCs. Additionally, quantitative RT-PCR, western blotting analysis, Alizarin Red S- and von Kossa staining revealed that 30% naHAp/SB induced odontoblastic differentiation of DPSCs, which was inhibited by a MEK/ERK inhibitor and CaSR antagonist. Furthermore, 30% naHAp/SB promoted dense reparative dentin formation in an experimentally-formed rat dental pulp exposure model. These findings suggest that 30% naHAp/SB can be used as an ideal direct pulp capping material.

Process Optimization of Microbially Induced Calcite Precipitation by Ureolytic Yeast Spathospora sp. NN04 using Box-Behnken Design: A Novel Approach towards Biocementation

Introduction: The present study was focused on the statistical optimization of growth parameters for enhancing the Microbially Induced Calcite Precipitation (MICP) using ureolytic yeast strain.Materials and Methods: Thirteen yeast strains were tested for the synthesis of urease enzyme by phenol-hypochlorite assay and were further evaluated for calcite precipitation test. The growth parameters were optimized using the best ureolytic strain by Box-Behnken Design (BBD) and the extracted MICP was characterized through instrumental analysis.Results: Among thirteen yeast strains, Candida tropicalis NN4, Spathospora sp. NN04, Wickerhamomyces anomalus VIT-NN01 and Candida dubliniensis NN03 showed positive results for the synthesis of urease enzyme. Spathospora sp. was found to be the most potent strain for MICP. A significant enhancement in MICP by Spathospora sp. was observed under optimized conditions viz. A-urea concentration (80.0 g/L), B-calcium chloride (45.0 g/L), C-pH (9.0) and D-inoculum dosage (8%, v/v). The actual value (34.4±0.12 g/L) was in agreement with predicted value (34.7±0.01 g/L) with the R2 value (0.9900), confirming the validity of the model. The FTIR of MICP confirmed the fundamental bands of CO3 stretching and bending vibrations, observed at 1394.23 and 874.85 cm-1. The Scanning Electron Microscope (SEM) images of biomotar revealed aggregated polymorphs of MICP interconnected with yeast mycelium and spores. The Energy Dispersive X-Ray Spectrometer (EDX) analysis indicated the presence of calcite in the biomotar. A remarkable improvement in the compressive strength (28 to 44 MPa) and morphological changes were observed in biocement mortar as compared to cement mortar.Conclusions: This result is the first report on the implementation of ureolytic Spathospora towards the application of biocementation through MICP using BBD.