SEM-energy Dispersive X-ray Research Articles

PolyCitrulline Modified Glassy Carbon Electrode as a Voltammetric Sensor for the Simultaneous Determination of Metabolic Syndrome Biomarkers-Uric Acid and Tyramine

Abstract This article describes the development of a simple and sensitive voltammetric sensor for the simultaneous determination of Uric acid (UA) and Tyramine (TYM), which act as metabolic syndrome (Mts) biomarkers. The electropolymer of the naturally occurring amino acid citrulline (Cit) has been employed as the electrode modifier in this sensor. Glassy carbon electrode modified with poly citrulline has been characterized with the aid of techniques such as scanning electron microscopy (SEM) and SEM-energy dispersive X-ray analysis, surface area calculations and electrochemical impedance spectroscopy. Studies were carried out to optimize parameters like the cycles of polymerisation, supporting electrolyte and its pH. The sensor which offers fast determination of the analytes using square wave voltammetry possesses a limit of detection 1.32×10-8 M and 4.20×10-8 M for UA and TYM, respectively. The applicability of the sensor in body fluids has been proved through spike recovery analysis in artificial blood serum and urine samples. Interference on the voltammetric signals created by some dominant coexisting species of the analytes was found to be tolerable.

Ternary composite WS2/GO/Au synthesized from laser ablation and hydrothermal method for photo- and electro-chemical degradation of methylene blue dye

Photocatalysts based on two-dimensional (2D) material with full optical absorption in the visible region have gained a lot of interest as a potential method for the degradation of pollutants, but there are very few single materials that can fulfill this requirement. In this research, we are suggesting the formation of WS2/GO/Au ternary composite prepared by WS2 and GO using nanosecond laser ablation followed by adding Au using the hydrothermal method. Ultraviolet-visible (UV–Vis), Raman, x-ray diffraction (XRD) spectroscopies, and field emission scanning electron microscopy (FE-SEM) were used to investigate the microstructure, morphology, and spectroscopic properties of the samples that had been produced. The UV–Vis spectra suggest the formation of a ternary composite, and FE-SEM shows morphology as Au nanoparticles with a size ranging from 20 to 30 nm are perfectly mixed with WS2 nanosheets, which can be seen on GO sheets. SEM-Energy dispersive x-ray spectroscopic (EDS) images indicate the availability of all elements in prepared samples and the formation of a ternary composite of WS2/GO/Au. XRD and Raman spectroscopy confirm the crystalline nature of AuNPs and WS2 and suggest the transformation of GO into rGO. The prepared pristine (WS2), binary (WS2/GO), and ternary composite show the capability for methylene blue degradation under UV-light irradiation as 41.85 %, 48.26 %, and 83.17 %, while electrocatalytic degradation gives 99 % for WS2/GO/Au respectively. The improved photocatalytic activity by the multicomponent has been demonstrated by nanostructured catalysts with specific morphology due to their exceptional electron transport characteristics. The WS2/GO/Au composite is anticipated to be an encouraging photoelectric material for experimental study in the research area of photocatalysis.

Sustainable fabrication of biogenic Fe–Zn nano core-shell and their photocatalytic efficiency against third generation antibiotics

The photocatalysis of third generation antibiotics was deliberated using biogenic iron oxide (FeO NPs) and iron-zinc (Fe–Zn) nano core-shell. Photocatalysts were prepared from aqueous extract of Adiantum incisum (Ai) by reacting with apposite salt solutions. FeO NPs were synthesized by mixing 5 % Ai extract with 5 mM FeSO4.7H2O at alkaline pH (50 °C). While Fe–Zn nano core-shell were synthesized by coating ZnO NPs on FeO NPs using successive reduction method. Synthesis and stabilization of nanoparticles were substantiated by diverse surface plasmonic resonance peak of FeO NPs and Fe–Zn nano core-shell at explicit wavelength ranges. Band gap energy values, Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Raman and Scanning Electron Microscope (SEM) analysis validates that coating was done efficaciously. Fourier Transform Infrared Spectroscopy (FTIR) recognized the role of plant phytochemicals in NPs reduction and stabilization. SEM-Energy Dispersive X-Ray analysis (EDX) analysis unveiled that FeO NPs and core-shell aggregates are orbicular in shape. Average crystalline size of FeO NPs and Fe–Zn nano core-shell obtained from XRD was 15.64 nm and 22.94 nm respectively. The photocatalytic degradation of Ampicillin, Levofloxacin and Ceftriaxone under UV and Sunlight displayed that Fe–Zn nano core-shell have high degradation capability than FeO NPs. Degradation potential was higher in UV than in sunlight. Maximum degradation of Ampicillin (74.4 %) was attained under UV light and (60.31 %) in sunlight followed by Levofloxacin. Degradation was further confirmed by conducting FTIR analysis and antimicrobial studies. Gas Chromatography-Mass Spectrometry detected Hexadecenoic acid as the main degradation product in nano treated Ampicillin and Levofloxacin.

Samarium-modified NBT ceramics: a comprehensive exploration of cumulative effects

In the present report, ceramic specimens of sodium bismuth titanate [Na0.5(Bi1-xSmx)0.5TiO3] were prepared through solid-state reaction method with variations in the dopant concentrations specifically, x = 0.0, 0.1, 0.3, 0.5. The structural, optical, mechanical, and magnetic properties of lead-free NBT ceramics were investigated. The rhombohedral phase with space group R3c was confirmed in all prepared ceramic samples using X-ray diffraction patterns and Rietveld analysis. SEM micrographs and Energy Dispersive x-ray spectroscopy (EDAX) assess the morphology, grain size, overall structure, and stoichiometry of the developed compounds. FTIR spectroscopy was used for characterizing and identifying the functional groups. UV–vis spectroscopy revealed that band gap values decreased as dopant concentration increased, confirming the use of NBT-based perovskite as a photoactive material. PL spectra at room temperature exhibited reddish-orange emission. Colour coordinates and CCT values are in the range of 3483 K to 5912 K. At a concentration of x = 0.3, the materials displayed a high Vickers hardness of 8.20 GPa and exhibited minimal wear with low frictional coefficient values. Ferromagnetic behaviour at room temperature (RTFM) was detected in Sm-modified ceramic samples, as confirmed by the VSM study. The cumulative effect impact of the rare earth dopant cation at the Bi-site of NBT was widespread and demonstrated significant potential for use in optoelectronic devices.

Structural, optical, Raman characteristics of C-nanospheres incorporated Gd2O3:SeO2 nanoclusters for energy storage applications

In the present work, novel nanocrystals (NCs) of carbon nanospheres (Cx) (5%, 10%, and 15%) anchored on Gd3+:SeO2 (Cx:Gd3+@SeO2) were synthesized and characterized by XRD (x-ray diffraction), SEM (scanning electron microscopy), SEM-energy dispersive x-ray, UV-visible, x-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, and Raman analytical techniques. XRD analysis showed that the synthesized Cx:Gd3+@SeO2 NCs exhibit mixed tetragonal phase. Gd3+@SeO2 NCs transformed into irregular flake-like morphology with increasing percentage of Cx. Optical property studies showed the presence of Cx in Gd3+@SeO2 NCs matrix leads to tuning of bandgap (Eg). Incorporation of Cx leads to decrease in the bandgap from 3.64 to 3.58 eV. XPS investigation revealed chemical composition and valence state of Cx:Gd3+@SeO2 NCs. Carbon-based materials, especially, carbon nanospheres, have attracted much attention due to their good conductivity, low cost, high surface area, porosity, etc. Upon doping Cx, the conducting network of the Gd3+@SeO2 lattice is improvised, which forms hollow structures and facilitates penetration of the electrolyte. Raman studies confirmed the formation of Gd-O-Gd/Gd2O3, Se-O-Se/SeO2, and C-H (D and G) fringes. Supercapacitor properties of Cx:Gd3+@SeO2 NCs investigated in 3M KOH solution using three electrode system showed specific capacitance of 239.4 F/g at current density of 0.5 A/g with 89% capacitance retention over 3000 cycles. The synthesized nanocrystals can be used as potential candidates for optical devices and battery applications.

Pd nanoparticles supported on magnetic CoTiMgLDH with enhanced catalytic activity in Suzuki cross‐coupling and reductive degradation of dyes

With an aim to combine the catalytic properties of Pd nanoparticles (NPs) with the excellent characteristics of porous layered double hydroxides (LDH), in the present study, four different catalysts (Pd/Fe3O4‐CoTiMgAlLDH, Pd/Fe3O4‐CoTiMgLDH, Pd/Fe3O4‐CoTiAlLDH and Pd/Fe3O4‐CoTiLDH) were synthesized by supporting Pd NPs onto four different Fe3O4‐LDH supports, which were synthesized by varying the metals in LDH. The catalytic activity of these catalysts was studied for Suzuki coupling and reductive degradation of dyes. Pd/Fe3O4‐CoTiMgLDH outperformed the other catalysts in both reactions. The synthesized catalysts were examined via different characterization techniques like X‐ray diffraction (XRD), Brunauer–Emmett–Teller analysis (BET), X‐ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), high resolution transmission electron microscopy (HR‐TEM), field emission scanning electron microscopy (FE‐SEM), energy dispersive X‐ray (EDX), energy dispersive X‐ray mapping (SEM–EDX mapping), inductively coupled plasma atomic emission spectroscopy (ICP‐AES) and vibrating sample magnetometry (VSM). On the basis of results obtained from XPS and the experimental data, Fe3O4‐CoTiMgLDH was found to be the support of choice as it not only stabilized the Pd0 NPs but also increased the electron density on the anchored Pd0 species, which enhanced the catalytic activity of Pd/Fe3O4‐CoTiMgLDH for studied organic transformations.

Biologically-induced synthetic manganese carbonate precipitate (BISMCP) for potential applications in heavy metal removal

Heavy metal pollution of water is a burning issue of today’s world. Among several strategies involved for heavy metal remediation purpose, biomineralization has shown great potential. Of late, research has been focused on developing effective mineral adsorbents with reduced time and cost consumption. In this present paper, the Biologically-Induced Synthetic Manganese Carbonate Precipitate (BISMCP) was produced based on the biologically-induced mineralization method, employing Sporosarcina pasteurii in aqueous solutions containing urea and MnCl2. The prepared adsorbent was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD) and BET surface area analyzer. EDX analysis showed the elements in the crystal BISMCP were Mn, C, and O. XRD result of BISMCP determined the crystal structure, which is close to rhodochrosite (MnCO3). Spectral peaks of FTIR at 1641.79 cm−1 confirmed the appearance of CO binding, with strong stretching of CO32− in Amide I. From the six kinds of BISMCP produced, sample MCP-6 has the higher specific surface area by BET analysis at 109.01 m2/g, with pore size at 8.76 nm and higher pore volume at 0.178 cm3/g. These specifications will be suitable as an adsorbent for heavy metal removal by adsorption process. This study presents a preliminary analysis of the possibility of BISMCP for heavy metals adsorption using ICP multi-element standard solution XIII (As, Cr, Cd, Cu, Ni, and Zn). BISMCP formed from 0.1 MnCl2 and 30 ml of bacteria volume (MCP-6) produced a better adsorbent material than others concentrations, with the adsorption efficiency of total As at 98.9%, Cr at 97.0%, Cu at 94.7%, Cd at 88.3%, Zn at 48.6%, and Ni at 29.5%. Future work could be examined its efficiency adsorbing individual heavy metals.

Laser Application in Remineralisation of Enamel after Interproximal Reduction: An In-vitro Scanning Electron Microscopic Study

Introduction: Interproximal Reduction (IPR) or reproximation of enamel is of prime importance in orthodontics for correcting arch length-tooth size discrepancies. Despite its widespread application, IPR has been associated with adverse effects on the enamel surface. Aim: The aim of this study was to investigate whether laser application, when combined with fluoride application, enhances the remineralisation potential of enamel. Materials and Methods: This in-vitro study was conducted at Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai, Tamil Nadu, India, from December 2021 to July 2022. It involved 54 extracted teeth, divided into three groups of 18 samples each. Reproximation of 0.25 mm was performed on the proximal enamel surface of each tooth. Group 1 served as the control, group 2 was subjected to Fluor Protector, and group 3 received low-level laser therapy (Er,Cr:YSGG) after Fluor Protector application. Fluor Protector (Ivoclar Vivadent) was applied for seven days. Following the seven-day fluoride administration, a laser treatment using 0.75 W of power and 8.5 J/cm2 of energy was applied for 20 seconds. Microhardness testing was conducted on the samples using a Vickers Hardness Tester. All specimens underwent surface topographic analysis with Scanning Electron Microscopy (SEM) and were evaluated for mineral content (% weight) using SEM-Energy Dispersive X-Ray analysis (EDX). Paired t-tests were performed to compare the pre- and post-microhardness values, while one-way Analysis Of Variance (ANOVA) test and Tukey’s Post-hoc test were used to compare the microhardness values between the groups. Results: The mean microhardness values recorded for group 1, group 2, and group 3 were 209.4±18.4 N/mm2 , 215.16±21.0 N/ mm2 , and 233±18.05 N/mm2 , respectively. ANOVA test revealed a significant difference in microhardness values between group 1 and group 2 (p-value=0.004), as well as between group 1 and group 3 (p-value=0.001). The microhardness value was highest for group 3, followed by group 2 post-intervention. SEM analysis showed that laser-treated enamel surfaces were smoother, with well-coalesced enamel rods. The porous structure of enamel was lost due to fluoride deposition in group 2 and group 3, resulting in a smooth surface. Conclusion: The combined application of fluoride and laser therapy demonstrated synergistic effects in remineralising the slenderised enamel. This simple, non-invasive technique may benefit patients undergoing IPR procedures by reducing the occurrence of dental caries.

Enhancement of the Mechanical Properties of a Geopolymer Concrete Due to Chemical and Microstructural Interaction of the Binder Material

Many experimentation and researchers were made in the recent decades in concrete and advancement in the field of concrete technology were given a major focus. In the years of research, many new replacement materials were identified and further details studies over the materials were made to have a clear and better idea about the material. In this study, the binder which is to be cement basically is replaced with a combination of Alccofine-1203(A), Metakaolin (MK), and Ground Granulated Blast-furnace Slag (GGBS) in different ratios to arrive a geopolymer concrete mix. In addition, the study also focuses on the chemical interaction of the replacement material and its microstructure interaction. The liquid binder (l/b) ratios varied between 0.48 to 0.54, and about seven geopolymer concrete mixes were arrived and experimental investigation done for mechanical property. The maximum compressive strength obtained from the mix proportions G50M35A15 at an l/b ratio of 0.50 was taken as a mix design for the Geopolymer mix. The identified combination of Granulated Blast-furnace Slag, Metakaolin, Alccofine-1203 (GMA) is used for further study. In general, when finer particles were replaced or added to the material, the finer particle will reduce the voids and thereby increasing the strength of the concrete by developing a denser material combination. Experimentally, results proves that there is a significant hike in the mechanical behaviour of the concrete. The microstructure investigation is carried out through SEM analysis and energy dispersive X-ray analysis (EDAX) which indicated a good interlocking characteristics of the materials which inturn directly impacts the mechanical properties of the concrete.

Real-time monitoring of stress corrosion cracking in 304 L stainless steel pipe using acoustic emission

A stress corrosion cracking (SCC) monitoring indicator (MI) based on the acoustic emission (AE) technique is proposed for the real-time detection and monitoring of SCC initiation in 304 L stainless steel (SS) pipes used for the primary circuits of nuclear power plants (NPPs). A device is used to accelerate the initiation of SCC to shorten the experiment timeframe. A non-crack AE signal criterion was established, which was conducted by injecting an etchant and distilled water into 304 L SS pipe specimens as experimental and control groups, respectively. Furthermore, to characterize the AE signal responsible for cracking, the characteristics of the AE signal measured in the section between necking and fracture (where cracks occur and propagate) among the stress curves obtained from the 304 L SS tensile test using AE sensors were investigated. Subsequently, the maximum amplitude, energy, frequency characteristics (range and magnitude), and waveform of the remaining AE signals were investigated after removing some AE signals by applying the non-crack AE signal criterion in the experiment where the SCC penetrated the pipe. These were compared with the maximum amplitude, energy, frequency characteristics, and waveform which were investigated in the tensile test to derive common characteristics for the two sets of crack signals to establish an SCC MI. To evaluate the performance of the developed SCC MI, the SCC monitoring experiment was halted when AE signals corresponding to the SCC MI criteria were measured, to fabricate a pipe wherein non-penetrating SCC was formed. In this manner, by applying the SCC MI to detect SCC in real time, we verified that the SCC MI had excellent SCC detection performance. Furthermore, we performed scanning electron microscopy (SEM) image analyses and SEM-energy dispersive X-ray spectrometry analyses to investigate the causes of SCC propagation.

Intelligent framework for mineral segmentation and fluid-accessible surface area analysis in scanning electron microscopy

Imaging is powerful means of sample characterization where mineral abundances and surface areas can be quantified from mineral maps. Images are typically manually processed by domain experts, which is time-consuming, labor intensive, and subjective. Emerging techniques, such as machine learning based image processing, can potentially address these limitations and accelerate image processing but the performance of these models for accurate sample characterization and surface area analysis has not been completely evaluated. This study evaluates the potential of Random Forest and U-Net machine learning methods for mineral characterization and surface area analysis of six sandstone samples. Various input variable sets including filter extracted features, scanning electron microscopy (SEM) backscatter electron (BSE) images and SEM-energy dispersive x-ray spectroscopy images (EDS) images were considered. The evaluation was conducted by providing an intelligent framework that not only evaluates the accuracy of prediction for each pixel but also investigates the accuracy of predicted neighboring pixels. In addition, a new methodology is proposed to distinguish the more susceptible places to dissolution on the surface of a given mineral using a ranked mineral dissolution risk assessment map. The results showed both methods had an acceptable performance with the U-Net model outperforming Random Forest. Both methods showed an improved accuracy when filter extracted features were added to the dataset as input variables. The models’ performance predicting mineral abundances and accessibility agreed well with ground truth data for majority classes (e.g., quartz) compared to minority classes. Finally, the proposed methodology was shown to reliably identify the locations susceptible for dissolution indicated via proposed risk assessment maps. The intelligent segmentation and surface area analysis framework is a promising tool for accelerating the processing of SEM data and reactivity assessment of samples.

Synthesis of Higher Alcohols from Syngas over a K-Modified CoMoS Catalyst Supported on Novel Powder and Fiber Commercial Activated Carbons.

In the present study, a series of K-modified CoMoS catalysts with compositions of 10% K, 3.6% Co, and 12 wt % Mo supported over novel commercial activated carbons such as powder materials (DAC and OBC-1) and fiber materials (fabric active sorption (TCA) and nonwoven activated material (AHM)) were prepared and characterized by Brunauer-Emmett-Teller (BET), X-ray fluorescence (XRF), scanning electron microscopy (SEM), SEM–energy dispersive X-ray (EDX), and transmission electron microscopy (TEM). The catalytic activities for higher alcohol synthesis from syngas, conducted at T = 300–360 °C, P = 5 MPa, GHSV = 760 L h–1 (kg cat)−1, and H2/CO = 1.0, were investigated. Cat-TCA and Cat-AHM have shown a filamentous morphology with a strip axial arrangement and that a few longitudinal grooves and many irregular particles are distributed on the fiber surfaces. The degree of entanglement of the strip axial arrangement in AHM was found to be more than that in TCA, thus leading to form tangled MoS2 slabs on AHM and long linear slabs on TCA with long rim sites. The obtained results revealed that the CO conversion increases in the order Cat-TCA < Cat-OBC-1 < Cat-DAC < Cat-AHM. Ethanol, propanol-1, and methanol are the most predominant alcohol products in the collected liquid products, with the byproducts containing mainly butanol-1, isobutanol, amyl alcohol, and isoamyl alcohol. Cat-DAC and Cat-OBC-1 show higher selectivity toward C3+, C4+, propanol-1, butanol-1, isobutanol, and amyl alcohol-1 than Cat-TCA and Cat-AHM. For powdered activated carbons, microporous catalysts inhibited isomerization because the catalyst that contains the highest micropores (Cat-DAC) produced a considerable amount of linear alcohols compared with Cat-OBC-1.

Analysis of particles containing alpha-emitters in stagnant water at torus room of Fukushima Dai-ichi Nuclear Power Station’s Unit 2 reactor

Particles containing alpha (α) nuclides were identified from sediment in stagnant water in the torus room of the Fukushima Dai-ichi Nuclear Power Station(FDiNPS)’s Unit 2 reactor. We analyzed uranium (U), which is the main component of nuclear fuel, using scanning electron microscopy (SEM). Other α-nuclides (plutonium [Pu], americium [Am], and curium [Cm]) were detected by alpha track detection and the morphology of particles with α-nuclides were analyzed by SEM-energy dispersive X-Ray (EDX) analysis. Several uranium-bearing particles ranging from sub-µm to several µm in size were identified by SEM observation. These particles contained zirconium (Zr) and other elements which constituted fuel cladding and structural materials. The 235U/238U isotope ratio in the solid fractions that included U particles was consistent with what was found for the nuclear fuel in the Unit 2 reactor. This indicated that the U of similar fuel composition had made finer. The α-nuclide-containing particles identified by alpha track analysis were several tens to several hundred µm in size. The EDX spectra showed that these particles mainly comprised iron (Fe). Since the amount of α-nuclide material was very small, Pu, Am, and Cm were adsorbed on the Fe particles. This study clarifies that the major morphologies of U and other α-nuclides in the sediment of stagnant water in the torus room of FDiNPS’s Unit 2 reactor differed.

Fouling mitigation in an anaerobic membrane bioreactor via membrane surface modification with tannic acid and copper

Anaerobic membrane bioreactors (AnMBRs) have recently received a great amount of attention as an alternative anaerobic treatment process due to their superior capability for sludge retention with high effluent quality. Nevertheless, membrane fouling in AnMBRs has been a major concern. In this study, the surfaces of polyvinylidene fluoride (PVDF) ultrafiltration membranes were modified with tannic acid (TA) and Cu(II) at various molar ratios of TA to Cu(II), including 3:1, 2:1, 1:1, 1:2, and 1:3. The hydrophilicity, morphology, chemical structure, elemental composition, and antibacterial properties of the unmodified and modified membranes were analyzed using water contact angle measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), SEM-energy dispersive X-ray spectrometry (SEM-EDX), and the clear zone method, respectively. The modified membrane with a TA-to-Cu(II) molar ratio of 1:3 had high hydrophilicity with certain antibacterial properties; therefore, it was selected to be further tested in an AnMBR along with an unmodified membrane. The chemical oxygen demand (COD) removal efficiencies of the unmodified membrane and modified membrane were 92.2 ± 3.6% and 91.8 ± 4.0%, respectively. The modified membrane had higher permeability after backwashing with less chemical cleaning (CC) than the unmodified membrane. Surface modification with TA and Cu(II) appeared to reduce irreversible fouling on the membranes.

SEM-EDS and microindentation-driven large-area high-resolution chemomechanical mapping and computational homogenization of cementitious materials

The need for the chemomechanical characterization of composite materials of unknown composition arises in many fields, including in the study of ancient and biological materials. The exact properties and distributions of their constituent phases are often poorly understood, which makes the study of their effective properties more challenging. In this work, a chemomechanical framework for the homogenization of such composites is presented and applied to a series of cement-based mortars. First, backscattered scanning electron microscopy (BS-SEM) and SEM energy dispersive X-ray spectroscopy (SEM-EDS) are used to chemically characterize large sample regions at high resolution. Next, k-means clustering is used with the quantitative SEM-EDS elemental data to obtain the spatial distributions of each sample’s chemically distinct constituent phases. Microindentation is used to obtain the local elastic properties of the aggregate phase, and microindentation and compression testing are used to obtain the local elastic properties of the binding phase of each sample. The data is then combined to form high-resolution maps of mechanical properties, which are used as the initial configurations of finite element models that are then subjected to uniaxial compression and pure shear deformations to investigate the microstructure response. The results are used to estimate the effective Young’s modulus and shear modulus of each sample. It is shown that when the hardened cement paste phase is homogenized a priori using compression testing, the framework yields Young’s modulus estimates with errors of 3.0–27.7%. A parametric study of the role of the reduced stiffness at the cement paste-aggregate interfaces shows that these errors may be further reduced to 1.4–6.0%.

Synthesis of ternary magnetic nanoparticles for enhanced catalytic conversion of biomass-derived methyl levulinate into γ-valerolactone

Conversion of levulinic acid and its esters into versatile γ-valerolactone (GVL) is a pivotal and challenging step in biorefineries, limited by high catalyst cost, the use of hydrogen atmosphere, or tedious catalyst preparation and recycling process. Here we have successfully synthesized a ternary magnetic nanoparticle catalyst (Al2O3-ZrO2/Fe3O4(5)), over which biomass-derived methyl levulinate (ML) can be quantitively converted to GVL with an extremely high selectivity of > 99% and yield of ~98% in the absence of molecular hydrogen. Al2O3-ZrO2/Fe3O4(5) incorporates simultaneously inexpensive alumina and zirconia onto magnetite support by a facile coprecipitation method, giving rise to a core-shell structure, well-distributed acid-base sites, and strong magnetism, as evidenced by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle annular dark-field scanning-TEM (HAADF-STEM), SEM-energy dispersive X-ray spectroscopy (SEM-EDX), temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed desorption of carbon dioxide (CO2-TPD), pyridine-adsorption infrared spectra (Py-IR), and vibrating sample magnetometry (VSM). Such characteristics enable it to be highly active and easily recycled by a magnet for at least five cycles with a slight loss of its catalytic activity, avoiding a time-consuming and energy-intensive reactivation process. It is found that there was a synergistic effect among the metal oxides, and the high efficiency and selectivity originating from such synergism are evidenced by kinetic studies. Furthermore, a reaction mechanism regarding the hydrogenation of ML to GVL is proposed by these findings, coupled with gas chromatography-mass spectrometry (GC-MS) analysis. Accordingly, this readily synthesized and recovered magnetic nanocatalyst for conversion of biomass-derived ML into GVL can provide an eco-friendly and safe way for biomass valorization.

Analysis of Corrosion of Hastelloy-N, Alloy X750, SS316 and SS304 in Molten Salt High-Temperature Environment

Nickel superalloy Hastelloy-N, alloy X-750, stainless steel 316 (SS316), and stainless steel 304 (SS304) are among the alloys used in the construction of molten salt reactor (MSR). These alloys were analyzed for their corrosion resistance behavior in molten fluoride salt, a coolant used in MSR reactors with 46.5% LiF+ 11.5% NaF+ 42% KF. The corrosion tests were run at 700 °C for 100 h under the Ar cover gas. After corrosion, significant weight loss was observed in the alloy X750. Weight loss registered in SS316 and SS304 was also high. However, Hastelloy-N gained weight after exposure to molten salt corrosion. This could be attributed to electrochemical plating of corrosion products from other alloys on Hastelloy-N surface. SEM–energy-dispersive X-ray spectroscopy (EDXS) scans of cross-section of alloys revealed maximum corrosion damage to the depth of 250 µm in X750, in contrast to only 20 µm on Hastelloy-N. XPS wide survey scans revealed the presence of Fe, Cr, and Ni elements on the surface of all corroded alloys. In addition, Cr clusters were formed at the triple junctions of grains, as confirmed by SEM–EBSD (Electron Back Scattered Diffraction) analysis. The order of corrosion resistance in FLiNaK environment was X750 &lt; SS316 &lt; SS304 &lt; Hastelloy-N.

Microstructure and Material Properties of Ti-15mass%Nb Alloy after Gas Nitriding and Quenching Process

The α′ martensite of Ti-15mass%Nb alloy exhibits high internal friction with high damping properties. However, its structure is smoother than the α + β structure. Therefore, a hardened surface layer is required for abrasion resistance. This study fabricated a martensite structure inside the nitriding layer by quenching, after gas nitriding at 1023 and 1223 K. Vickers hardness test, X-ray diffraction, scanning electron microscopy (SEM), and SEM-energy dispersive X-ray (SEM-EDX) measurements from the surface to the inside were made after the heat treatment process. In addition, the Young’s modulus and internal friction were calculated from the damping analysis. The α-TiN0.3 and β phase region was formed at approximately 80 µm from the surface at 1023 and 1223 K, and it was hardened. The internal friction of the gas nitriding and quenching specimens at 1023 and 1223 K was relatively high, though it did not reach that of the as-quenched specimen owing to the influence of the surface structure. From these results, it is considered that these material property values of the alloy can be controlled using the nitriding and quenching processes.

Characterization and Morphology of Natural Dung Polymer for Potential Industrial Application as Bio-Based Fillers.

The modern-day paper industry is highly capital-intensive industries in the core sector. Though there are several uses of paper for currency, packaging, education, information, communication, trade and hygiene, the flip side of this industry is the impact on the forest resources and other ecosystems which leads to increasing pollution in water and air, influencing several local communities. In the present paper, the authors have tried to explore potential and alternate source of industrial pulp through ruminant animal dung, which is widely available as a rural resource in India. Three types of undigested animal dung fibers from Indigenous cow (IDF), Jersey cow (JDF), and Buffalo (BDF) were taken. Wheat straw (WS) was the main diet of all animals. The cellulose, hemicellulose and lignin content for all animal dung samples were found in a range of (29–31.50%), (21–23.50%), and (11–13%), respectively. The abundant holocellulose and low lignin contents are suitable for handmade pulp and paper. Surface characteristics of fodder (WS) and all dung fibers have been investigated using Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), and SEM-Energy dispersive X-ray spectroscopy (SEM-EDX). To increase paper production without damaging forest cover, it is essential to explore unconventional natural resources, such as dung fiber, which have the huge potential to produce pulp and paper, reinforcement components, etc.

An impedimetric biosensor system based on disposable graphite paper electrodes: Detection of ST2 as a potential biomarker for cardiovascular disease in human serum

In present study, we developed a highly sensitive, electrochemical immunosensor based on fullerene C60-modified disposable graphite paper (GP) electrode for determination of Suppression of Tumorigenicity 2 (ST2) in human serum. The synthesis of the ST2 immunosensor was monitored with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) techniques and single frequency impedance (SFI) technique which is utilized for the specific interaction between anti-ST2 and ST2 antigen. Moreover, the morphological alteration of each GP surface was examined by scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). All parameters such as fullerene C60 concentration, antibody concentration and antibody incubation time were optimized. Analytical characteristics such as linear determination range, repeatability, reproducibility, regeneration and surface coverage were determined for the immunosensor. The ST2 electrochemical immunosensor had excellent repeatability, reproducibility and a wide detection range (from 0.1 fg mL−1 to 100 fg mL−1). The proposed immunosensor also had low limit of detection (LOD) and limit of quantification (LOQ) values of 0.124 fg mL−1 and 0.414 fg mL−1, respectively. The proposed immunosensor was applied to real samples to test applicability in clinical practice.