Scanning Electron Microscopy-energy Dispersive X-ray Spectroscopy Research Articles

Technical examination of Wat Sisowath Ratanaram panel painting

The technical examination on the early 20th century panel painting of Wat Sisowath Ratanaram was performed using optical microscopy (OM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), Micro-Raman spectroscopy (μ-RAMAN), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The investigation shows the mixture of minium, cinnabar and baryte in red preparation layer, quartz from the natural earth pigment in the underpaint layer and the pigments mixed with the additives in the paint layer. There are various pigments found in the paint layer ranging from emerald green, chalk, baryte, chrome yellow, ultramarine blue, carbon black and zinc white. Zinc white was widely utilized as the additive of green, yellow and blue paint layer. In addition, minium and carbon black were used to draw fine lines for image details. The degradation products of gypsum in the paint layer were evidenced by SEM-EDS and XRD. While the darkening of red lead in the red preparation layer was observed by OM. The trace of natural plant resin as a binding meium was found in S_Wood and S_Black samples evidencing by ATR-FTIR and Py-GC/MS. The 7 steps of painting technique were proposed by implementing all detailed scientific information.

In situ growing of ZIF-8 crystals into TiO2 micro columnar films

This study proposes a fast and simple method for the in situ growth of metal-organic frameworks (MOFs) on metal oxide substrates as an alternative to the traditional approaches of using gold substrates and self-assembled monolayers (SAMs). As a case study, zeolitic imidazolate framework 8 (ZIF-8) crystals were grown in micro columnar TiO2 films through simple alternate and successive immersions of the TiO2 films into solutions containing the MOFs precursors. The growth process of the MOF crystals in the interstitial spaces between the TiO2 columns was investigated by varying the metal-to-ligand ratio (1:2, 1:4, and 1:8) and by employing modulating agents such as triethylamine. It was found that the optimal deposition of ZIF-8 occurred when using a higher excess of ligand and the addition of triethylamine after a controlled number of immersion cycles. These results were obtained by using glancing angle X-ray diffraction (GAXRD) and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) as characterization techniques. Additionally, a density functional theory (DFT) study as well as Fourier-transform infrared spectroscopy (FTIR) and GAXRD experiments were conducted to elucidate the nucleation process. It was concluded that the starting point is the formation of a covalent bond between the Zn cations and the TiO2 on the metal oxide surface after immersion of the film into a Zinc (II) nitrate solution, allowing for the formation of MOF nuclei once the film is subsequently immersed in the 2-methylimidazole solution. The results demonstrate the feasibility of in situ growth of MOF crystals onto metal oxide structures by a layer-by-layer strategy, offering a promising alternative to conventional methods.

Mineral-dependent release, migration and enrichment of toxic elements during black shale weathering: An integrated study from profile scale to mineral scale.

Chemical weathering of lithologies with high geochemical backgrounds such as black shale has been proposed to be a critical source for toxic elements in soil and water systems. However, mechanisms controlling the release, migration and enrichment of toxic elements during black shale weathering are poorly understood. This study utilized a suite of micro analytical techniques such as TESCAN integrated mineral analyzer (TIMA), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and electron micro-probe analysis (EMPA) to elucidate the intimate relationship between mineralogical transformations and elemental behaviors from profile scale to mineral scale. Mineralogical and elemental compositions for a black shale weathering profile (and surface strongly weathered materials) suggest a dominant sequence of mineral reactions as oxidation of sulfides, dissolution of carbonates, alteration of aluminosilicates, and transformation of clay minerals. Most of the toxic elements were largely released from the weathering profile and significantly enriched in the strongly weathered materials. Black shale weathering was initiated by oxidation of pyrite, sphalerite and molybdenite, and these chemical reactions dominated the release of toxic elements (e.g., As, Cd, Mo, Mn, Ni and Zn). During oxidation of pyrite, Fe (hydr)oxides pseudomorphically replaced pyrite grains, along with the release of As and Mn and their subsequent retention in Fe (hydr)oxides. Sulfuric acid generated by oxidation of sulfides firstly dissolved surrounding calcite and dolomite to significantly improve the pore-fracture networks in the weathered shale, allowing more water fluxes and transportation of Fe (hydr)oxides and concomitant migration of associated toxic elements. Then, albite and minor orthoclase were altered to illite that was responsible for the secondary enrichment of Tl throughout the weathering profile. In intense weathering stage, Fe/Mn (hydr)oxides were substantially delivered to re-precipitate in fractures and contributed to considerable enrichment of As, Ni, Co, Zn and Cd. Meanwhile, transformation of illite to kaolinite may also influence the enrichment of toxic elements. This work highlights the importance of understanding the control of mineralogical transformation on release, migration and enrichment of toxic elements during black shale weathering, such that this mineral-dependent mechanism can be implemented to risk prediction and assessment of toxic elements in black shale regions.

Source and Ecological Risk Assessment of Potentially Toxic Metals in Urban Riverine Sediments Using Multivariate Analytical and Statistical Tools

Multivariate and statistical tool advancements help to assess potential pollution threats, their geochemical distribution, and the competition between natural and anthropogenic influences, particularly on sediment contamination with potentially toxic metals (PTMs). For this, riverine sediments from 25 locations along urban banksides of the River Ravi, Pakistan, were collected and analyzed to explore the distribution, pollution, ecological, and toxicity risk indices of PTMs like Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sn, Sr, V, and Zn using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) technique. Additionally, techniques such as X-ray Diffraction (XRD) and Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM-EDS) were employed to investigate the mineralogical and morphological aspects. The results indicated that mean concentrations (mg kg−1) of Cd (2.37), Cr (128), Hg (16.6), Pb (26.6), and Sb (2.44) were significantly higher than reference values given for upper continental crust (UCC) and world soil average (WSA), posing potential threats. Furthermore, the geochemical pollution indices showed that sediments were moderately polluted with Cd (Igeo = 2.37, EF = 12.1, and CF = 7.89) and extremely polluted with Hg (Igeo = 4.54, EF = 63.2, and CF = 41.41). Ecological and toxicity risks were calculated to be extremely high, using respective models, predominantly due to Hg (Eri = 1656 and ITRI = 91.6). SEM-EDS illustrated the small extent of anthropogenic particles having predominant concentrations of Zn, Fe, Pb, and Sr. Multivariate statistical analyses revealed significant associations between the concentrations of PTMs and the sampling locations, highlighting the anthropogenic contributions linked to local land-use characteristics. The present study concludes that River Ravi sediments exhibit moderate levels of Cd and extreme pollution by Hg, both of which contribute highly to extreme ecological and toxicity risks, influenced by both natural and anthropogenic contributions.

Strategically Designed Ternary Nanohybrids of Titanate Nanosheet and Polydopamine-Coated Carbon Nanotubes for Highly Efficient Enrichment of Uranium(VI).

A strategically designed ternary nanohybrid (TNS-PDA/CNT), consisting of titanate nanosheet (TNS) and polydopamine-modified multiwalled carbon nanotube (PDA/CNT composite), was synthesized by the facile hydrothermal method and wet impregnation method for removal of U(VI) from aqueous solution and were characterized by transmission electron microscopy (TEM), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), Raman spectroscopy, Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). TNSs were introduced into the PDA/CNT composite, which effectively averted the agglomeration of the CNT and further exposed more adsorption sites. PDA thin layer exposing more active sites was conducive to enhance adsorption capacity and kinetic. The adsorption process was largely influenced by pH values and weakly affected by ionic strength, indicating that the adsorption process was controlled by inner-sphere surface complexes because of TNS-PDA/CNT with multiple functional groups, including imine, catechol, amine, and hydroxyl groups. The isotherm data could be well described by the Langmuir model, and the monolayer maximum adsorption was determined to be 309.60 mg/g at pH = 5.0 and temperature = 45 °C. Thermodynamic parameters (ΔG° < 0, ΔS° > 0, and ΔH° < 0) showed that the nature of adsorption was endothermic and spontaneous. By XRD, FT-IR, and XPS analyses, the adsorption mechanism mainly involved surface complexation and ion exchange. In summary, the TNS-PDA/CNT materials are fully qualified as a satisfactory adsorbent for the purification and recovery of U(VI) from wastewater.

Preparation of Ca2MnO4 films using Bayesian optimization and their black color properties owing to Ti4+-doping

Abstract Ca2MnO4-based films were prepared by using a sol–gel method and Ti4+ ions were doped into the Mn4+ site to control their color properties. For non-doped Ca2MnO4 films, several preparation conditions were screened by using Bayesian optimization. In the Ca2(Mn,Ti)O4 film samples that were prepared under suitable conditions, the target phase was obtained as a main phase and the solid solutions were formed. Scanning electron microscopy–energy-dispersive x-ray spectroscopy analysis elucidated that an intermediate layer of CaSiO3 with 1 µm was formed between the film and substrate, and hence the Ca/Mn ratio became Ca-poor closer to the intermediate layer. The film samples showed strong optical absorption in the visible-light region simultaneously with weak absorption in the near-infrared (NIR) region. The bandgap energy of the film sample was also found to decrease by doping with Ti4+, resulting in a color change from blackish brown to black. Accordingly, the films had high NIR-reflectivity/transmittivity and the deep black coloration was controlled by the Ti4+-doping.

Effect of Li-Mg Alloy Anode on Li Dendrite Suppressionfor Li-Air Secondary Batteries

Non aqueous Li-air battery (LAB) has been attracting much attention as one of the next-generation batteries because it has a theoretical capacity about ten times that of the conventional Li-ion battery (3505 Wh kg-1). However, there is a risk of short-circuit due to Li dendrite formation on the surface of Li metal anode by charge/discharge cycling. Recently, a small amount of Mg addition into the Li metal anode was reported to work as a good scaffolding and suppress the Li dendrites in Li-sulfur batteries (LSBs) [1]. In addition, the SEI film derived from the Li-Mg alloy anode reduced an electrolyte decomposition and improved the cycle performance of LSBs. Moreover, the Li-Mg alloy anode has a higher Li diffusion coefficient than pure Li one, and the interfacial stability between the electrolyte and electrode was also improved [2]. However, there are almost no report on its application to LABs. In this study, Li dissolution/deposition behavior under O2 gas atmosphere was investigated using a Li-Mg | Li-Mg symmetric cell to reveal the effect of Mg addition into the Li metal anode.The Li | Li and Li-Mg | Li-Mg symmetric cells was assembled using 1.0 M LiTFSI/G4 electrolyte solution, a pair of 0.5 mm thick pure Li foil, Li-10 wt%Mg (Li-0.1Mg) and Li-20 wt%Mg (Li-0.2Mg) alloy foil, and PE separator in a dry box filled with Ar gas. The Li dissolution/deposition test was repeated upto 200 cycles at a constant current density of 0.50 mA cm-2 in the voltage range of -2.0 V to 2.0 V under the O2 atmosphere, and the magnitude of overvoltage and flatness of the polarization curves were evaluated. Each resistance value was also analyzed by AC impedance measurement for each charge /discharge cycle. Furthermore, the electrode surfaces before and after the cycle tests were evaluated by a scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis to investigate the differences in the Li and Mg deposition morphology and the chemical composition of SEI films. Fig. 1 shows the polarization curves for the Li | Li and Li-Mg | Li-Mg symmetric cells. In the case of pure Li metal, the overpotential increased from 120th cycle. This suggests that Li dendrite gradually formed and caused to increase in the surface area of Li metal and electrolyte decomposition, following to generate a relatively thick SEI film. On the other hand, Li-0.1Mg alloy electrode shows smaller overpotential through the 200 cycles. This indicates that the Li-0.1Mg alloy electrode suppressed the Li dendrite by stabilizing the interphase between the electrode and electrolyte solution. In contrast, the Li-20 wt%Mg alloy electrode rather increased the overpotential during initial cycle, but gradually reduced it and was stabilized as same as Li-10 wt%Mg alloy one. These results were in good agreement with the morphologies of electrode surface after the cycling tests by SEM observation.The results of SEM-EDS and XPS analyses in more detail, their correlation, and the mechanism of the effect of Mg addition into the Li metal electrode will be presented in the meeting.

Pt Re Electrodes for AEM Water Electrolysis: Catalytic Insights and Performance Optimization for the Hydrogen Evolution Reaction

The urgent global imperative to mitigate climate change and transition towards sustainable energy sources has propelled the search for cost-effective alternatives to fossil fuels. Green hydrogen, produced via water electrolysis powered by renewable energy, stands as a promising solution in this endeavor. However, for green hydrogen to become a viable competitor to fossil fuels, it is crucial to drive down production costs. One promising avenue is thrifting precious group metal (PGM) electrocatalysts with more abundant and cost-effective metals, thereby reducing the overall cost of hydrogen production. In this context, the replacement, alloying, and thrifting of PGM materials hold significant potential. By leveraging cheaper and earth-abundant metals such as rhenium (Re) (currently, $2,000/Kg) and nickel (Ni) (currently, $20/Kg), respectively, in place of platinum (Pt) (currently, $31,000/Kg), the cost of green hydrogen production can be brought to a level that competes with fossil fuel prices [1], [2], [3]. This shift not only fosters sustainability but also reshapes global energy markets, steering them away from carbon-emitting sources towards clean, carbon-free alternatives like hydrogen. In this study, we explore the deployment of an anion exchange membrane water electrolyzer (AEMWE) cathodic hydrogen evolution reaction (HER) electrocatalyst: PtRe dispersed on a porous carbon support alloy (PtRe/C) as a potential replacement for conventional Pt on carbon (Pt/C) catalysts. We investigate two different loadings of PtRe/C (40-10 wt.% PtRe and 25-25 wt.% PtRe/C) and compare their performance against benchmark electrocatalysts, including 50 wt.% Pt/C and 30-3 wt.% PtNi/C. Through a comprehensive analysis involving X-ray Diffraction (XRD), Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy (SEM-EDS), Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES) and electrochemical characterization via Rotating Disk Electrode (RDE), Gas Diffusion Electrode (GDE) half-cell, and Membrane Electrode Assembly (MEA) testing, we demonstrate superior performance of PtRe/C alloys. In-house MEA testing revealed durability of 25-25 wt.% PtRe/C out to 100 h of continuous (steady state) operation at 1 A/cm2 at ~1.8 V with negligible voltage decay. Additionally, 40-10 wt.% PtRe/C performed exceptionally well with durability out to 100 h at 1 A/cm2 and 1.9 V. PtNi/C had the highest overvoltage of 1.95 V at continuous 1 A/cm2. Polarization curves (transient) reveal the best performing catalyst to be 25-25 wt.% PtRe, reaching a overvoltage of 1.7 V at 1 A/cm2 in beginning of life testing while 40-10 wt.% PtRe/C and PtNi/C perform comparably with 1.79 V and 1.83 V at 1 A/cm2 during polarization, respectively. Our findings underscore the potential of alloying and thrifting strategies in advancing the cost-effectiveness and efficiency of green hydrogen production, thereby contributing to the transition towards a sustainable energy future.

Identification of laccol as a paint binder in Neolithic pottery from China

Some precious painted pottery have been excavated from a late Neolithic site (6000-5300 BP) in China recently. The materials and technique of the paint were comprehensively studied. The analytical techniques conducted include optical microscope (OM), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDS), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), Ultra Performance Liquid Chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) and thermally assisted hydrolysis-methylation pyrolysis-gas chromatography/mass spectrometry (THM-Py-GC/MS). The results revealed the painted pottery is lacquer-painted pottery, which is the earliest evidence of using laccol as binding media to paint pottery. Moreover, a two-layer structure of the paint technique was found. Cinnabar and a kind of yellow dye were detected in the first layer, while iron red was determined in the ground layer. Laccol, instead of urushiol as a binding medium, was identified in both two layers. Laccol is the maker compound from the tree of Toxicodendron (Rhus) succedanea, which mainly grows in Vietnam. Its presence in the painted pottery represents that the use of Toxicodendron (Rhus) succedanea resource can be as early as the late Neolithic period in China. The possibility of the origin of laccol was also discussed in the paper.

Efficiency of a novel cysteine-polypyrrole@silver phosphate nanocomposite for hazardous Cr(VI) removal: Experimental study and statistical optimization modeling

A novel cysteine functionalized-Polypyrrole@silver phosphate (Cys-PPy@Ag3PO4) nanocomposite, synthesized through chemical polymerization was used for fully reducing Cr(VI) to Cr(III) and successfully capturing the Cr(III), representing a major leap in Cr(VI) remediation technology. Assorted analytical approaches, such as Fourier-transforms infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron (XPS) spectroscopy, Brunauer-Emmett-Teller (BET), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), were implemented to explore the morphology and removal mechanism. The nanocomposite exhibited a mesoporous structure enriched with nitrogen/oxygen functional groups, which improved the diffusion, adsorption, and reduction of Cr(VI) ions. At pH 2, 96.50 % of Cr(VI) was removed using 0.5 g.L−1 of adsorbent in 60 min. Besides, the maximum uptake capability was 149.76 mg.g−1, and both Freundlich isotherm and PSO kinetic models perfectly aligned with the adsorption experimental findings for Cr(VI) species. Analysis of thermodynamic factors revealed that Cr(VI) adsorption was endothermic and spontaneous, enhancing the disorder of Cr(VI) species on the nanocomposite surface. XPS and FT-IR analysis proved that Cr(VI) ions were electrostatically adsorbed and subsequently converted to Cr(III), which were then immobilized through chelation with imine/sulfonate groups and electrostatic attraction with carboxylate groups. The nanocomposite showcased effortless regenerability through basification and outstanding reusability. Overall, Cys-PPy@Ag3PO4 proved highly effective in removing Cr(VI) from water. Environmental ImplicationThis study focuses on the synthesis of a novel adsorbent with reduction capabilities. Thus, the hazardous Cr(VI) ions were successfully removed from aqueous solutions, providing an alternative for environmental remediation. Hence, the reductive behavior of the synthesized adsorbent converted the toxic Cr(VI) into Cr(III). This adsorbent was regenerated with basic media, enabling its usage for 4 cycles, and reducing spent adsorbent disposal. Thus, the desorption process favored not only the adsorbent reuse but also the attainment of a less harmful effluent-containing Cr(III).

Electrocapacitive removal of Na and Cd ions from contaminated aqueous solution using Fe3O4-poly (3,4-ethylenedioxythiophene) poly(styrene sulfonate) modified chitosan nanosheets

Chitosan nanosheets (NS) stabilized on poly (3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) was functionalized using Fe3O4 to capacitively remove chloride ions and toxic cadmium ions at optimized pH, concentration, and number of charging cycles. The synthesis procedure was investigated by Fourier transform infrared spectroscopy (FTIR), X-Ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Scanning Electron Microscope – Energy Dispersive X-ray Spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller (BET). The analyses confirms increase in surface area of the nanocomposite from 41 to 132 m2/g and a decrease in crystallinity from 75.3 to 66.9% after nanosheet formation. The highest sorption exchange capacity (SEC) for this work, 93% CdCO3 removal is achieved at 100 CDI cycles while 82% NaCl removal was achieved at 80 cycles. The SEC% increased with pH during Na ion deionization and decreased with pH during Cd removal. The works shows that chitosan is able to impart advanced structural properties to Fe3O4 and PEDOT and is able to reduce reverse migration of ions from electrodes to bulk solution, leading to higher SEC performance.

Reaction Mechanism of Oxytetracycline Degradation by Electrogenerated Reactive Chlorine: The Influence of Current Density and pH.

A binary dimensionally stable anode Ti/TiO2-RuO2 electrode was used to abate the antibiotic oxytetracycline (OTC) (C22H24N2O9) in chloride water. The anode was prepared using the Pechini method and subsequently characterized by X-ray diffraction, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), and cyclic voltammetry (CV). The optimum values of the operational parameters affecting removal efficiency were determined using a 2 × 3 factorial design by screening j (6.0, 10, and 20 A m-2) and pH (3, 6.5, and 10). The textural analysis revealed the formation of active oxides (RuO2 and TiO2 coating rutile-type P42/mnm, space group 136), with a cracked surface and good dispersion of metal components. A contour graph verified that the most suitable condition for contaminant degradation was 20 A m-2 at a circumneutral pH of 6.5, resulting in approximately 97% degradation after 20 min of electrolysis according to pseudo-first-order reaction kinetics and the loss of the antibiotic activity of OTC. In addition, the results of oxidant formation and CV indicate that the best electrochemical activation of the anode to form Cl2-active mainly depended on pH. Liquid chromatography-mass spectrometry (LC-MS) and density functional theory were employed to propose a reaction pathway for OTC degradation. Three byproducts with m/z 426, 256, and 226 were identified corresponding to the removal of amide and amine groups, which are susceptible sites to electrophilic attack by active chlorine species. The findings from this work stand out for prospective applications of anodic electrochemical oxidation to efficiently eliminate antibiotics with similar chemical structures in wastewater containing chlorides.

Unveiling a novel exopolysaccharide produced by Pseudomonas alcaligenes Med1 isolated from a Chilean hot spring as biotechnological additive

Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermotolerant (growth from 34–44 °C) strain Pseudomonas alcaligenes Med1 from Medano hot spring (39.1 °C surface temperature, pH 7.1) located in the Central Andean Mountains of Chile. Bacterial growth was screened for temperature tolerance (10–60 °C) to confirm the thermotolerance behaviour. Physicochemical properties of the EPS were characterized by different techniques: Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). Whole genome of P. alcaligenes Med1 has also been studied in detail to correlate the structural and functional characteristics with genomic insight. The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps composed of mainly carbon and oxygen. The monosaccharide analysis has shown the presence of glucose, galactose, and mannose sugars at different ratios. TGA revealed the high thermal stability (315.3 °C) of the polysaccharide. The GPC has shown that Med1 is a low molecular weight polysaccharide (34.8 kDa) with low PI. The 2D-NMR linkage analysis suggests a diverse array of glycosidic bonds within the exopolysaccharide structure. The functional properties of the EPS were evaluated for food industry applications, specifically for antioxidant (DPPH, FRAP an H2O2). Extracted Med1 EPS revealed significant emulsification activity against different food grade vegetative oils (Coconut oil, Corn oil, Canola oil, Avocado oil, Sunflower oil, Olive oil, and Sesame oil). The highest 33.9% flocculation activity was observed with 60 mg L−1 EPS concentration. It showed water-holding (WHC) of 107.6% and oil-holding (OHC) capacity of 110.8%. The functional EPS produced by Pseudomonas alcaligenes Med1 from Central Andean Chilean hot spring of central Chile can be a useful additive for the food-processing industry.

Safety and security of household water purifiers against pathogenic microbial contamination and bio-risk evaluation of their microbial community structures

Household water filters, particularly point-of-use systems, are crucial to ensure safe drinking water consumption by eliminating microbial contaminants. This study evaluated the efficacy of three types of water purifiers (ultrafiltration [UF], nanofiltration [NF], and reverse osmosis [RO]) against microbial contamination. In our experiments, Escherichia coli and bacteriophage MS2 were used as two microbial indicators in daily household settings to track the spatial and temporal profiles of their behavior from the filter inlets to in-UF, NF, and RO water purifiers, and then to effluents. The results showed that both NF and RO water purifiers removed 100 % of the indicator organisms. The UF water purifier achieved 100 % removal of E. coli, but the removal of MS2 phage was poor. The presence of coexisting ions and natural organic matter in tap water can significantly affect the behavior of MS2 phages during the water treatment process. Their presence reduces the charge repulsion effect of the UF membrane on the MS2 phage as well as promotes the migration of the MS2 phage on the post-activated carbon cartridge that was placed in the last unit of the water purifier system, which could increase the pathogen transmission risks in drinking water supplies. The bacterial community structures of the cartridge materials and cartridge effluents from each unit were analyzed by 16S rRNA gene sequencing, which revealed distinct microbial profiles of the different purifiers. Environmental conditions such as pH, nutrient availability, materials, and operational parameters can affect the composition of bacterial communities. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) was used to examine the surface morphology of the membranes after they were exposed to water contaminants, which demonstrated that the inherent differences in the membrane structure influenced the retention of pollutants and microorganisms on the surfaces. In summary, this study demonstrates that both NF and RO water purifiers can significantly reduce the presence of various enteric and opportunistic pathogenic bacteria in drinking water, leading to safer potable water, whereas UF water purifiers may have certain risks owing to their UF membranes and post-activated carbon. In addition, secondary microbial contamination may be introduced by the post-activated carbon units of water purifiers, especially after long-term usage. Therefore, we concluded that addressing the secondary microbial pollution caused by post-activated carbon after prolonged use and long-term shutdown is essential for maintaining the safety and quality of drinking water.

Diffuse punctate deposits on the surface of hydrophilic acrylic intraocular lenses early postoperatively: case series and laboratorial analyses.

To describe cases of hydrophilic acrylic intraocular lenses (IOLs) (Eyecryl, Biotech) exhibiting surface punctate deposits early postoperatively and provide laboratorial analyses of unused lenses of the same model. Altino Ventura Foundation (FAV), Recife, Brazil, and John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. Observational, descriptive, clinical study with laboratorial analysis. A thorough review of records of patients undergoing phacoemulsification with Eyecryl implantation in December 2022 at FAV was performed, with data collection. 5 Eyecryl IOLs (never implanted/unused) were removed from the original package and underwent gross examination, light microscopy, and ultrastructural analyses using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Details on 5 clinical cases exhibiting surface IOL deposits on the first postoperative day after uneventful surgery and followed for at least 6 months were included. The deposits disappeared by the 60th postoperative day. No inflammatory or toxic reactions were noted, visual outcomes were favorable, and IOL explantation was not necessary. 3 of the 5 unused lenses undergoing laboratorial analyses revealed diffuse, star-like deposits that could not be removed by thorough irrigation with distilled water. SEM/EDS revealed a composition of the deposits that primarily consisted of carbon and oxygen. Laboratorial findings suggest the etiology of the deposits might be related to the manufacturing/packaging process of lenses from specific lots. Although the deposits did not appear to be associated with inflammatory or toxic reactions in the clinical cases, further investigations are necessary to elucidate their precise origin.

Removal of Pb(II) and Cd(II) from a Monometallic Contaminated Solution by Modified Biochar-Immobilized Bacterial Microspheres.

Lead (Pb) and cadmium (Cd) are toxic pollutants that are prevalent in wastewater and pose a serious threat to the natural environment. In this study, a new immobilized bacterial microsphere (CYB-SA) was prepared from corn stalk biochar and Klebsiella grimontii by sodium alginate encapsulation and vacuum freeze-drying technology. The removal effect of CYB-SA on Pb(II) and Cd(II) in a monometallic contaminated solution was studied. The results showed that the removal of Pb(II) and Cd(II) by CYB-SA was 99.14% and 83.35% at a dosage of 2.0 g/L and pH = 7, respectively, which was 10.77% and 18.58% higher than that of biochar alone. According to the Langmuir isotherm model, the maximum adsorption capacities of Pb(II) and Cd(II) by CYB-SA at 40 °C were 278.69 mg/g and 71.75 mg/g, respectively. A combination of the kinetic model, the isothermal adsorption model, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses showed that the main adsorption mechanisms of CYB-SA encompass functional group complexation, ion exchange, electrostatic attraction and physical adsorption. The findings of this study offer practical and theoretical insights into the development of highly efficient adsorbents for heavy metals.

Long-term Chinese milk vetch incorporation promotes soil aggregate stability by affecting mineralogy and organic carbon

Soil aggregates profoundly impact soil sustainability and crop productivity, and they are influenced by complex interactions between minerals and organics. This study aimed to elucidate the alterations in mineralogy and soil organic carbon (SOC) following long-term green manure incorporation and the effect on soil aggregates. Based on 5- and 36-year field experiments, surface soil samples (0-20 cm) were collected from Alfisol and Ferrisol soils subjected to rice-rice-winter fallow (CK) and rice-rice-Chinese milk vetch (MV) treatments to investigate aggregate stability, mineralogy, SOC composition, and soil microstructural characteristics. The results showed that high clay-content Ferrisol exhibited greater aggregate stability than low clay-content Alfisol. The phyllosilicates in Alfisol primarily comprised illite and vermiculite, whereas those in Ferrisol with high-content free-form Fe oxides (Fed) were dominated by kaolinite. Additionally, the clay fraction in Ferrisol contained more aromatic-C than the clay fraction in Alfisol. The 36-year MV incorporation significantly increased the Ferrisol macroaggregate stability (9.57-13.37%), and it also facilitated the transformation of vermiculite into kaolinite and significantly increased the clay, Fed, and aromatic-C contents in Ferrisol. Backscattered electron (BSE)-scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) revealed a compact aggregate structure in Ferrisol with co-localization of Fe oxides and kaolinite. Moreover, the partial least path model (PLS-PM) revealed that clay content directly improved macroaggregate stability, and that kaolinite and Fed positively and directly affected clay or indirectly modulated clay formation by increasing the aromatic-C levels. Overall, long-term MV incorporation promotes clay aggregation by affecting mineral transformation to produce more kaolinite and Fe oxides and retain aromatic-C, and it ultimately improves aggregate stability..

The effect of thermal aging on microhardness and SEM/EDS for characterisation bioactive filling materials

BackgroundThe aim of this study is to evaluate the surface microhardness, surface chemical composition of bioactive restorative materials pre- and post- thermal aging.MethodA total of 200 disc-shaped samples were prepared by using the materials: Cention N, ACTIVA BioActive Restorative, Equia Forte HT Fil, Glass Fill glass carbomer cement (GCP), and Fuji II LC. Vickers microhardness test were used to measure surface hardness. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM/EDS) was used to determine the characterization of the microstructures and elemental analysis of the materials. These measurements were repeated after thermal aging. One-Way ANOVA test, Bonferroni test and the Games-Howell test was used for data analysis. The significance level was accepted as 0.05.ResultsCention N had the highest vickers microhardness value before thermal cycle. The highest fluoride ion ratio among the materials before thermal aging was detected in the Equia Forte HT Fil and Fuji II LC groups. While a decrease in fluorideF ion was detected in all groups except the Cention N group after thermal aging. It is observed that ACTIVA BioActive Restorative has a more microporous and rougher surface in the scanning electron microscopy image after the thermal cycle than in the image before the thermal cycle.ConclusionsThe chemical properties of the materials and the properties of the filler particles may be related to the differences in the mechanical properties, surface characterizations and ion releases of the materials Thermal aging affected the microhardness, surface characteristics and elemental mass ratios of the studied materials. Alkasite bioactive materials are more similar to composite restorative materials and show better mechanical properties than other materials, but do not have the same effect on fluoride release.Clinical relevanceMost of the bioactive materials showed a decrease in the fluoride ion ratio after thermal aging, while no difference was found in the ion exchange of alkasite materials. Material selection should be made more carefully in caries-active individuals whose fluoride release is clinically important.

Application of microscopic imaging, multispectral techniques, and SEM/EDS analysis to the study of 19th century colour engravings

This study was carried out on a collection of coloured gravures, which are bound in one book volume entitled “Histoire Naturelle des Perroquets”. This book belongs to the Benaki's Collection of the Hellenic Parliament Library, Athens, Greece. Each page has a coloured print, depicting a different bird species. In most cases, the prints present oxidations caused by the additives used in paper and printing inks manufacture, i.e. fillers, sizing agents, binders, solvents, and other chemical compounds.By employing microscopic imaging, multispectral imaging, and Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDS) analysis significant information on the materials used, engraving techniques, as well as the preservation state of the printings studied can be obtained. The combination of the proposed methods yields successful results in identifying the materials used in the colour inks, as well as the paper support of the printings.

A facile synthesis procedure for Engelhard titanosilicate (ETS-4) and its Cs+ and Sr2+ ion exchange properties

This manuscript reports an environmentally benign method for the synthesis of Engelhard titanosilicate (ETS-4) using titanium isopropoxide or anatase as titanium source and citric acid as complexing agent. Slow release of Ti from the hydroxide or oxide precursors through the citric acid complex plays crucial role in formation of titanosilicate. Characterizations of the prepared material were carried out by powder X-ray diffraction (XRD), Scanning Electron Microscope – Energy Dispersive X-ray spectroscopy (SEM-EDS), Thermogravimetric – Differential Thermal Analysis (TG-DTA) and ion exchange studies. Caesium and strontium exchange capacities of the synthesised ETS-4 were found to be 220 mg/g and 76.2 mg/g, respectively. The saturation exchange equilibrium was attained within 60 min.