Electron Microscopy-energy Dispersive X-ray Research Articles

Green Synthesis of Copper Nanoparticles Using Polyalthia longifolia Roots and their Bioactivities Against Escherichia coli, Staphylococcus aureus, and Candida albicans

ABSTRACT The synthesis of copper nanoparticles (CuNPs) has been the center of researchers’ attention due to their potential in various fields, particularly in medicine and pharmacy. The objective of this research was to synthesize CuNPs by using the extract from Polyalthia longifolia roots via an organic solvent-free approach. The roots of P. longifolia were extracted using boiling water and subsequently used to synthesize CuNPs from CuSO4 solution. The resultant nanoparticles were then characterized using UV–Vis spectrophotometer, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope–energy dispersive X-ray (SEM-EDX), and transmission electron microscopy (TEM). Kirby–Bauer sensitivity test was performed against Staphylococcus aureus, Escherichia coli, and Candida albicans. In the results, we found that the total phenolic content and total flavonoid content of the extract were 85.43 GAE/g dry extract and 0.78 QE/g dry extract, respectively. The characterizations revealed that the obtained nanoparticles possess a spherical shape and diameters of around 2 to 10 nm. The XRD suggests that the nanoparticles were occupied by copper (0) and copper oxides (CuO, CuO2, and Cu2O). The synthesized CuNPs yielded inhibition zones of 17.2 ± 0.2, 15.6 ± 0.2, and 13.7 ± 0.1 mm against S. aureus, E. coli, and C. albicans, respectively. In conclusion, aqueous extract from the roots of P. longifolia can be used to synthesize CuNPs that could be used as an antibacterial and antifungal agent.

Characterization of an advanced bone graft material with a nanocrystalline hydroxycarbanoapatite surface and dual phase composition.

The bone formation response of ceramic bone graft materials can be improved by modifying the material's surface and composition. A unique dual-phase ceramic bone graft material with a nanocrystalline, hydroxycarbanoapatite (HCA) surface and a calcium carbonate core (TrelCor®-Biogennix, Irvine, CA) was characterized through a variety of analytical methods. Scanning electron microscopy (SEM) of the TrelCor surface (magnification 100-100,000X) clearly demonstrated a nanosized crystalline structure covering the entire surface. The surface morphology showed a hierarchical structure that included micron-sized spherulites fully covered by plate-like nanocrystals (<60 nm in thickness). Chemical and physical characterization of the material using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy Energy Dispersive X-ray Spectroscopy (SEM-EDX) showed a surface composed of HCA. Analysis of fractured samples confirmed the dual-phase composition with the presence of a calcium carbonate core and HCA surface. An in vitro bioactivity study was conducted to evaluate whether TrelCor would form a bioactive layer when immersed in simulated body fluid. This response was compared to a known bioactive material (45S5 bioactive glass - Bioglass). Following 14-days of immersion, surface and cross-sectional analysis via SEM-EDX showed that the TrelCor material elicited a bioactive response with the formation of a bioactive layer that was qualitatively thicker than the layer that formed on Bioglass. An in vivo sheep muscle pouch model was also conducted to evaluate the ability of the material to stimulate an ectopic, cellular bone formation response. Results were compared against Bioglass and a first-generation calcium phosphate ceramic that lacked a nanocrystalline surface. Histology and histomorphometric analysis (HMA) confirmed that the TrelCor nanocrystalline HCA surface stimulated a bone formation response in muscle (avg. 11% bone area) that was significantly greater than Bioglass (3%) and the smooth surface calcium phosphate ceramic (0%).

Novel starch–tungsten (VI) oxide biocomposites: Preparation, characterization, and comparisons between experimental and theoretical photon attenuation coefficients

This study synthesized biocomposites containing starch and WO3 at varying ratios of 10 %, 20 %, 30 %, 40 %, and 50 % and assessed their thermal and radiation-shielding properties. These biocomposites were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction (XRD) analysis, particle-size distribution assessments, scanning electron microscopy–energy dispersive X-ray spectroscopy, and thermogravimetric analysis–differential thermogravimetry measurements. Furthermore, the linear attenuation coefficients of the biocomposites were experimentally measured using an NaI(Tl) gamma spectrometry system and theoretically computed using XCOM and GAMOS simulations for comparisons. The XRD and particle-size distribution profiles of the WO3.2H2O powder, respectively, demonstrated evident diffraction peaks and favorable pore-size distributions. Morphological characterizations revealed that the WO3 particles were homogeneously dispersed throughout the starch matrix without any agglomeration. Comparisons of the thermal degradation rates revealed that the pure starch and starch +50%WO3 biocomposite began decomposing at approximately 200°Cand 300 °C, respectively, indicating that increasing WO3 proportions enhanced thermal stability. Furthermore, the starch +50%WO3 biocomposite demonstrated the highest experimental linear attenuation coefficient, with a value of 0.2510 ± 0.0848 cm−1 at a gamma energy of 662 keV. Meanwhile, XCOM and GAMOS simulations revealed theoretical attenuation coefficients of 0.1229 and 0.1213 cm−1 for pure starch and 0.2202 cm−1 and 0.2178 cm−1 for the starch +50%WO3 biocomposite at 662 keV, respectively.

Atomic-level investigation of structure and formation process of Y3Al5O12 with super-high content of Ce emitting anomalous orange-red emissions

Ce-doped yttrium aluminum garnet (YAG:Ce, Y3Al5O12:Ce) is the most commonly used yellow phosphor in white light-emitting diodes. Recently, we found that (Y1–xCex)3Al5O12:Ce with a super-high content of Ce (x = 0.11–0.21) can be prepared by a polymerized complex method and exhibits anomalous orange–red emission. To understand the nature of this anomalous behavior from the atomic level, we applied high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and scanning transmission electron microscopy–energy dispersive X-ray spectroscopy (STEM-EDS), a state-of-the-art technique that enables analysis of the atomic-level elemental distributions of Al, Y, and Ce. STEM-EDS images on the atomic level were successfully obtained for YAG:Ce. It was found that Ce in Y site has spatially uneven for few nanometers. Ce–K edge extended X-ray absorption fine structure (EXAFS) analysis was also conducted, which revealed a high level of asymmetry around Ce. By combining the STEM-EDS and EXAFS results, a dynamic model for the red emission was proposed. STEM-EDS also revealed that CeO2 nanocrystals were firstly formed with low-temperature annealing and that the reaction of Y with the CeO2 nanocrystals subsequently yielded YAG:Ce, unlike in the conventional one-step high-temperature synthesis.

Influence of TiO2 Nanoparticles on the Physical, Mechanical, and Structural Characteristics of Cementitious Composites with Recycled Aggregates.

The aim of this study is to analyze the effect of the addition of TiO2 nanoparticles (NTs) on the physical and mechanical properties, as well as the microstructural changes, of cementitious composites containing partially substituted natural aggregates (NAs) with aggregates derived from the following four recycled materials: glass (RGA), brick (RGB), blast-furnace slag (GBA), and recycled textolite waste with WEEE (waste from electrical and electronic equipment) as the primary source (RTA), in line with sustainable construction practices. The research methodology included the following phases: selection and characterization of raw materials, formulation design, experimental preparation and testing of specimens using standardized methods specific to cementitious composite mortars (including determination of apparent density in the hardened state, mechanical strength in compression, flexure, and abrasion, and water absorption by capillarity), and structural analysis using specialized techniques (scanning electron microscopy (SEM) images and energy dispersive X-ray spectroscopy (EDS)). The analysis and interpretation of the results focused primarily on identifying the effects of NT addition on the composites. Results show a decrease in density resulting from replacing NAs with recycled aggregates, particularly in the case of RGB and RTA. Conversely, the introduction of TiO2 nanoparticles resulted in a slight increase in density, ranging from 0.2% for RTA to 7.4% for samples containing NAs. Additionally, the introduction of TiO2 contributes to improved compressive strength, especially in samples containing RTA, while flexural strength benefits from a 3-4% TiO2 addition in all composites. The compressive strength ranged from 35.19 to 70.13 N/mm2, while the flexural strength ranged from 8.4 to 10.47 N/mm2. The abrasion loss varied between 2.4% and 5.71%, and the water absorption coefficient varied between 0.03 and 0.37 kg/m2m0.5, the variations being influenced by both the nature of the aggregates and the amount of NTs added. Scanning electron microscopy (SEM) images and energy dispersive X-ray spectroscopy (EDS) analysis showed that TiO2 nanoparticles are uniformly distributed in the cementitious composites, mainly forming CSH gel. TiO2 nanoparticles act as nucleating agents during early hydration, as confirmed by EDS spectra after curing.

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

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

A comprehensive characterization of indoor ambient microplastics in households during the COVID-19 pandemic

AbstractAirborne microplastics (MPs) can be easily inhaled by humans, impacting their health as they spend more than 80% of their time indoors, especially during the pandemic. Only a few research studies have examined indoor MPs in the micrometer size range using active sampling, and studies have mainly concentrated on MPs that are millimeters in size. This study investigated the composition of indoor airborne MPs by active sampling in seven houses in the city center of northwestern Turkey (Eskişehir) during the COVID-19 pandemic. The visual identification showed the presence of different colored MPs, white, red, orange, green, and yellow, with different shapes (fibers, fragments, films, lines, foam, and pellets). The size of the identified MPs was between 2.5 and 327.36 μm. The polymeric composition analysis showed the presence of 123 MPs in all the samples with 22 different polymeric compositions. Residents in these houses are exposed to airborne MPs, with inhalation estimates ranging from 12.03 to 18.51 MPs/m3. However, it was also estimated that humans inhale 156–240 MPs daily in these houses. The dominant MPs were polyamide 6, polyvinyl chloride, polypropylene, ethylene propylene, polystyrene, and high-density polyethylene. Scanning electron microscopy energy dispersive x-ray elemental analysis revealed the presence of common structural elements, additives, or vectors that are added or adsorbed to MPs like carbon, oxygen, fluorine, magnesium, silicon, chlorine, nitrogen, and aluminum. These indoor environments are prone to MP pollution. Still, the MP level varies due to different characteristics of indoor environments, like activities and the number of occupants/people in the space, etc. The smaller MPs in all the samples highlight the necessity for standardized techniques of MP collection.

On dry machining of AZ31B magnesium alloy using textured cutting tool inserts

Magnesium alloys have many advantages as lightweight materials for engineering applications, especially in the fields of automotive and aerospace. They undergo extensive cutting or machining while making products out of them. Dry cutting, a sustainable machining method, causes more friction and adhesion at the tool-chip interface. One of the promising solutions to this problem is cutting tool surface texturing, which can reduce tool wear and friction in dry cutting and improve machining performance. This paper aims to investigate the impact of dimple textures (made on the flank face of cutting inserts) on tool wear and chip morphology in the dry machining of AZ31B magnesium alloy. The results show that the cutting speed was the most significant factor affecting tool flank wear, followed by feed rate and cutting depth. The tool wear mechanism was examined using scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) analysis reports, which showed that at low cutting speed, the main wear mechanism was abrasion, while at high speed, it was adhesion. The chips are discontinuous at low cutting speeds, while continuous at high cutting speeds. The dimple textured flank face cutting tools facilitate the dry machining of AZ31B magnesium alloy and contribute to ecological benefits.

Synthesis and Characterization of Carbonate Hydroxyapatite from Pokea Clam Shells (&lt;i&gt;Batissa Violacea Var. Celebensis&lt;/i&gt;) by Precipitation and Hydrothermal Methods

Hydroxyapatite Carbonate (CHA) is a material that is found to have a composition more similar to bone, with a higher bioactivity than Hydroxyapatite (HA). CHA was synthesized using precipitation and hydrothermal methods using (NH4)2HPO4 as a phosphate source, NH4HCO3 as a carbonate source, and Pokea shells as a calcium source. In this study, the Pokea shells were crushed, calcined, and characterized based on physicochemical tests. CaO from Pokea shell contains 74.33% calcium. CHA was successfully produced by precipitation method at room temperature and hydrothermal at 120 C for 8 h. Sample characterization was carried out using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Scanning Electron Microscope Energy Dispersive X-Ray Spectroscopy (SEM-EDX). Based on XRD data, there are differences in the crystal size of CHA produced via precipitation and hydrothermal methods, where the crystal sizes of Precipitation CHA-1 and Hydrothermal CHA-2 are 6.388 nm and 25.969 nm. The FTIR results of both CHA show the functional groups typical of CHA, namely OH-, CO, CaO, PO43-, and CO32-. From the Ca/P EDX data results, Precipitation CHA-1 and Hydrothermal CHA-2 do not differ much, namely 1.71 and 1.69, and this value indicates that CHA has been formed.

Characterization of Tableware from Fábrica de Loiça de Sacavém—Linking Analytical and Documental Research

Fábrica de Loiça de Sacavém (ca. 1858–1994) was among the first to produce white earthenware in Portugal, becoming one of the country’s leading ceramic manufacturers during the late 19th to early 20th centuries. Research on white earthenware has accompanied the growing interest in post-industrial archaeology but is still poorly explored compared to more ancient ceramic productions. This study focused on the ceramic body, glazes, and colourants of tableware produced by Fábrica de Loiça de Sacavém during the first 50 years of its activity (1859–1910). A multi-analytical approach was selected to investigate the chemical and mineralogical composition of the ceramic body, glaze, and pigments using optical microscopy, variable-pressure scanning electron microscope energy-dispersive X-ray spectroscopy (VP-SEM-EDS), μ-Raman spectroscopy, μ-X-ray Diffraction (μ-XRD), and reflectance spectroscopy (hyperspectral image analysis). The studied tableware was produced with a Ca-poor siliceous–aluminous white earthenware ceramic body covered with transparent alkali lead or lead borosilicate glaze, and most colourants were complex Cr-based pigments. These results are in agreement with the little documental evidence from this period found in the manufacturer’s archives.

Characterization of Mn5Ge3 Contacts on a Shallow Ge/SiGe Heterostructure.

Mn5Ge3 is a ferromagnetic phase of the Mn-Ge system that is a potential contact material for efficient spin injection and detection. Here, we investigate the creation of Mn5Ge3-based contacts on a Ge/SiGe quantum well heterostructure via solid-state synthesis. X-ray diffraction spectra fitting indicates the formation of Mn5Ge3-based contacts on bulk Ge and Ge/SiGe. High-resolution scanning transmission electron microscopy imaging and energy dispersive X-ray spectroscopy verify the correct Mn5Ge3-based phase formation. Schottky diode measurements, transmission line measurements, and Hall measurements reveal that Mn5Ge3-based contacts serve as good p-type contacts for Ge/SiGe quantum well heterostructures due to having a low Schottky barrier height of 0.10eV (extracted from a Mn5Ge3/n-Ge analogue) and a contact resistance in the order of 1 kΩ. Furthermore, we show that these electrical characteristics have a gate-voltage dependence, thereby providing tunability.

Long-term corrosion of copper alloys in the soil: new aspects of corrosion morphology in archaeological vessels from south-western Iran

A group of copper-based objects excavated at Deh Dumen cemetery, in south-western Iran, was studied and analysed to examine the long-term corrosion morphology and mechanism in the soil burial environment. For this purpose, twenty-two samples from twenty-one copper-based vessels were studied and analysed using X-ray diffraction, scanning electron microscopy—energy dispersive X-ray spectroscopy, micro-Raman spectroscopy and metallography techniques. The results of the analyses showed that the majority of vessels are made of tin bronze, along with two arsenical copper samples. The extent of corrosion observed ranges from very thin corrosion crusts to thick crusts and entirely corroded structures. These three identified corrosion morphologies display a multi-layered corrosion stratigraphy as well as the preserved limit of the original surface. The corrosion crusts include internal tin-rich and external copper-rich layers, and the main corrosion mechanism for the formation of multi-layered corrosion crusts is decuprification or selective dissolution of copper during the long-term burial time in a moderately Cl-contaminated soil. The three identified corrosion morphologies are similar to the previously published morphologies, but some clear deviations are apparent and are discussed here.

Selective recovery of rare earth elements by smelting of magnets

Rare earth elements (REEs) play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars. Permanent magnets account for a quarter of total global REEs production and have high recycling value. In this study, smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe2O3. This separates REEs into a slag phase from an iron-rich metallic phase. B2O3 was also added to the system as a flux to lower the slag melting temperature. This minimizes REEs loss to the metallic phase and allows a more efficient phase separation. The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB (NdCeFeB) magnets. At 1350 °C and for 1 h, the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe2O3 and 40 wt% of B2O3. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron. After the selective removal of iron into the metallic phase, REEs are recovered from the slag phase through an acid leaching process allowing >99% of REEs recovery. Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique. The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.

Tracking element-mineral associations with unsupervised learning and dimensionality reduction in chemical and optical image stacks of thin sections

In-situ chemical analysis on thin sections is a cornerstone of geochemical research. Despite massive advances in digital image analysis, the interpretation of such data within the optical petrological context of the thin section has largely remained an analogue task in geochemistry. In this contribution, we registered optical and micro-chemical images from large thin section areas. Chemical datasets from scanning electron microscopy energy dispersive spectrometry (SEM-EDX) and Synchrotron X-ray fluorescence microscopy (S-XFM) were exported from proprietary software. We then evaluated two dimensionality reduction techniques against false-colour images and phase maps to test whether previously unnoticed features became discoverable. Principal component analysis (PCA) and deep sparse autoencoder (DSA) neural networks were used to summarise the multi-channel SEM-EDX and S-XFM into one single red-green-blue (RGB) representation each.Applied to an oceanic gabbro, a cratonic peridotite, and a pelagic limestone, the PCA-based dimensionality reduction was found to produce crisp RGB maps of phases with less noise than false-colour three-element RGB maps. They were registered with optical images to form a simple multi-channel input for pixel-based classification into classes (i.e., semantic segmentation). This was fast and worked well for typical igneous and metamorphic rocks (1–3 h routine). In the chemically quite homogenous limestone, the combined optical and S-XFM PCA input was successfully classified into many phases that were unclassifiable on the conventional SEM-EDX phase map. From the segmented optical and S-XFM PCA map, we exported pixel locations of classified accessory phases back into the original proprietary S-XFM software. This allowed quantification of trace elements whose X-ray peaks were invisible in the original S-XFM quantification.The DSA-based approach yielded phase maps with greater noise, but the technique was very strong at detecting subtle features. In the gabbro sample, the DSA image identified cryptic relict cores in clinopyroxene more clearly than in the previously used Cr concentration map. A DSA training set can be obtained on a small ROI to generate a consistent large area DSA image from which more fragmental cores were observed. For a ROI on the gabbro thin section, the DSA representation map and the blended optical image were segmented and inspected with a loupe tool. This allowed us to generate interactive histograms and bin-scatter concentration plots of selected phases and to search for co-variations of element concentrations. This approach can be expanded to include data from any in situ geochemical acquisition tools and may help discover previously unseen features in complex elemental imagery.

Unveiling the Radiative Electron-Hole Recombination of MoS2 Nanostructures at Extreme pH Conditions.

Nanostructures of MoS2 are in wide research for optoelectronic, energy and biological applications. Opto-electronic and biological applications requires the tuning of photoluminescence properties of MoS2 nanostructures. In this article, nanosized MoS2 is hydrothermally synthesized, and photoluminescence at extreme pH conditions (pH 1 and 13) is examined. As the photoluminescence gives a key to probe the radiative electron-hole recombination, here, photoluminescence emissions are used as an indicator to suggest the pattern of electron-hole recombination in the material at extreme pH conditions. Raman spectroscopy, dynamic light scattering, Scanning electron microscopic image and energy dispersive x-ray analysis are done for material confirmation. At pH 1 and 13 as-synthesized nanostructured MoS2 exhibited both upconversion and downconversion photoluminescence. The intensity of photoluminescence is varied with respect to pH. Excitation-dependent photoluminescence mechanisms and preliminary understanding on the ratio of quantum yields and life span of excited state of as-synthesized nanostructured MoS2 are unveiled here.

Analysis of Pigments Unearthed from the Yungang Grottoes Archaeological Excavations

The Yungang Grottoes, excavated during the 5th to 6th centuries AD, stand as a pinnacle of Buddhist sculpture, representing a precious world cultural heritage. Since their excavation, the grottoes have undergone multiple phases of painting, with a significant amount of pigment still present on the surfaces of the stone carvings. Since the 1990s, two large-scale archaeological excavations have been conducted on both the front ground and the summit of Yungang Grottoes. During these excavations, various artifacts with accompanying pigments were unearthed, encompassing stone carvings, grinding tools, architectural components, fragments of murals, and remnants of clay sculptures, spanning the historical periods of the Northern Wei, Liao-Jin, and Ming-Qing dynasties. Using portable X-ray fluorescence spectrometry, portable microscopy, polarizing microscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, and confocal Raman microscopy, we conducted a comprehensive analysis of these painted elements. The investigation revealed the presence of hematite, vermilion, goethite, malachite, calcium carbonate, lead white, and ivory black pigments in the Northern Wei samples. The Liao-Jin samples exhibited hematite, while the Ming-Qing samples contained vermilion, minium, atacamite, lead white, and Prussian blue.

Trivalent lanthanum and ytterbium doped meso-silica/ceria abrasive systems toward chemical mechanical polishing (CMP) and ultraviolet irradiation-assisted photochemical mechanical polishing (PCMP)

Ceria (CeO2)-based abrasives are widely utilized in ultra-precision grinding and chemical mechanical polishing (CMP) applications over silica materials due to their unique physicochemical properties. Both mechanical and chemical contributions to polishing processes are highly affected by the size, shape, structure, component, defect of CeO2 abrasives. Herein, the composites involved mesoporous silica (mSiO2) cores and La- or Yb-doped CeO2 shells were synthesized and characterized in terms of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, scanning transmission electron microscopy–energy dispersive X-ray mapping methods. The polishing effectiveness of the proposed composites toward quartz glass was experimentally evaluated under both CMP and ultraviolet irradiation-assisted photochemical mechanical polishing (PCMP) conditions. The polishing results indicated that the low-modulus mSiO2 cores strongly exerted the cushion effects for the friction and abrasion to substrates. Consequently, the heterostructured mSiO2/La-CeO2 and mSiO2/Yb-CeO2 abrasive systems offered nearly non-damage and ultra-smooth surfaces with angstrom-level roughness compared to conventional rigid abrasives. The enriched Ce3+ and oxygen vacancy defects at La- and Yb- doped CeO2 surfaces were responsible for the improvements of tribochemical and photochemical activities, thus allowing evidently enhanced removal efficiency with the assistance of ultraviolet irradiation. A possible polishing mechanism on the multi-component abrasive systems was also proposed.

Characterization of Chilean hot spring-origin Staphylococcus sp. BSP3 produced exopolysaccharide as biological additive

A type of high molecular weight bioactive polymers called exopolysaccharides (EPS) are produced by thermophiles, the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures. Over time, EPS became important as natural biotechnological additives because of their noncytotoxic, emulsifying, antioxidant, or immunostimulant activities. In this article, we unravelled a new EPS produced by Staphylococcus sp. BSP3 from an acidic (pH 6.03) San Pedro hot spring (38.1 °C) located in the central Andean mountains in Chile. Several physicochemical techniques were performed to characterize the EPS structure including 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), 1D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). It was confirmed that the amorphous surface of the BSP3 EPS, composed of rough pillar-like nanostructures, is evenly distributed. The main EPS monosaccharide constituents were mannose (72%), glucose (24%) and galactose (4%). Also, it is a medium molecular weight (43.7 kDa) heteropolysaccharide. NMR spectroscopy demonstrated the presence of a [→ 6)-⍺-d-Manp-(1 → 6)-⍺-d-Manp-(1 →] backbone 2-O substituted with 1-⍺-d-Manp. A high thermal stability of EPS (287 °C) was confirmed by TGA analysis. Emulsification, antioxidant, flocculation, water-holding (WHC), and oil-holding (OHC) capacities are also studied for biotechnological industry applications. The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes, like flocculation and natural additives in product formulation.Graphical

Novel plant waste-based cost-effective adsorbent to remove contaminants from sewage wastewater

Discharge of untreated or partially treated sewage wastewater into waterbodies contaminates soil and groundwater. Reducing heavily-laden contaminants from wastewater is an utmost necessity. Recently, the use of organic adsorbents has become a promising approach for wastewater treatment due to their efficacy and sustainability. Objectives of the present study are (a) to explore novel plant waste material for the synthesis of adsorbents (biochars) with and without modifications to reduce inorganic contaminants and excess nutrients from sewage wastewater (b) to validate the efficacy of novel synthesized biochars on germination of Vigna radiata when grown in sewage wastewater. Plant waste materials (Turmeric leaves, Cyperus roots, Juniper leaves, and berries) were collected after oil extraction and Fe-modified and pristine biochars were further synthesized at 500 °C. The highest heavy metals efficiency and maximum seedling germination was observed in biochars derived from turmeric leaf followed by Cyperus root > Juniper leaf > Juniper berry. Fe-modified Turmeric leaf biochar showed 83.9, 96.7, and 94.8% removal for Ni, As, and Pb, respectively. The highest removal for PO43−, NO3−, NO2−, Cl−, and SO42− were observed in Fe-modified Cyperus root biochar as 96, 88, 84, 70, and 70%, respectively. Fe-modification enhance the higher surface area of biochars in the order of CRMBC (143.21 m2 g−1) > TLMBC (93.317 m2 g−1) > JBMBC (79.561 m2 g−1) > JLMBC (77.764 m2 g−1) that amplified the adsorption capacity. Fe-modification developed mesoporous structures that made biochar more thermally stable which was confirmed by thermo-gravimetric analysis, scanning electron microscopy energy dispersive X-ray, and Fourier-transform infrared spectroscopy. Fe-modified biochars offer a sustainable and easily recoverable option for wastewater treatment to efficiently reduce inorganic contaminants and to make treated wastewater suitable for irrigation and other purposes.

Synthesis of TiO2/Fe2O3 Nanocomposites as Photocatalyst for Methyl Orange Degradation

Fe2O3/TiO2 composites were successfully synthesized using the sol-gel method. The photocatalytic performance of prepared nanocomposites to degrade methyl orange under UV light irradiation was systematically investigated. The Fe2O3 added and calcination temperature were varied to study their effect on psychochemical properties. Further, to study the effect of psychochemical properties of the prepared nanocomposites on photocatalytic activity, X-ray diffraction (XRD), and scanning electron microscope Energy Dispersive X-ray spectroscopy (SEM-EDS) characterization were conducted. The visible light active Fe2O3 photocatalyst managed to decrease the bandgap energy of the prepared composites from 3.32 eV to 1.95 eV. This decrease in the band gap energy led to the composite being more active under visible light and less active under UV light irradiation. A composite with 6% Fe2O3 content exhibits the smallest degradation efficiency of 14% in 180 min, while the pure TiO2 nanoparticles are 94%. The results in this study provided important implications for further research on the preparation of composite TiO2 with Fe2O3 co-catalyst showing a promising route for improving the visible light activity of photocatalysts.