Electron Microscopy Images Research Articles

Novel theoretical studies based on CIELab and deconvolution methods to characterize AuNPs aggregation processes

The study of the interaction of spherical gold nanoparticles when they undergo aggregation phenomena due to the presence of a ligand in solution is presented, based on both colorimetric parameters (using CIELab space) and traditional deconvolution analysis. The feasibility of using CIELab space for this purpose can be an important method to simplify the required instrumentation (colorimeter versus UV spectrophotometer) as well as being less time consuming compared with the traditional computational analysis. For these reasons, in this work we present the first experimental approach of the proposed methodology for its application in this field of research. The synthetized AuNPs employed in this work have been previously characterized by means of the maxima of their LSPR bands, zeta potential and electron microscopy images. The aggregation of spherical AuNPs (with a diameter of 12 nm) by an inert electrolyte (NaCl) is investigated in a first step with successfully results, allowing to obtain the characteristic CIELab parameters (a*, b* and L*). At a later stage, the color changes induced in the optical properties of the solution due to the interaction of AuNPs (with increasing diameters of 12, 25 and 33 nm) with an amino acid such as lysine at neutral pH, have been also described using the CIELab spatial framework. The obtained a*, b* and L* parameters of the CIELab space allow to characterize satisfactorily the color change from red to blue which describes the aggregation phenomena, relying on deconvolution analysis of the LSPR bands. The results obtained support the validity of the CIELab space as a valid tool for the investigation of the aggregation process of colloidal solutions. It will allow simplifying the whole process using simpler and cheaper instrumentation as well as a decrease in the required analysis time.

The influence of gamma radiation on the structure and morphology of AgNWs/GO nanocomposites

In this study, AgNWs/GO nanocomposites were prepared by mechanically mixing graphene oxide (GO) synthesized using a modified Hummers' method and silver nanowires (AgNWs) synthesized using a modified polyol method. These nanocomposites were subjected to gamma radiation at three different doses (8, 25, and 50 kGy). Modification of materials by gamma radiation is a very important issue in materials science. The effects of gamma radiation on the structure of the nanocomposites were investigated through X-Ray diffraction (XRD) analyses. Changes in morphology depending on the radiation dose were examined using transmission electron microscope (TEM) images. Elemental analysis was performed before and after irradiation. For GO irradiated at a dose of 25 kGy, the strain and dislocation density values reached their highest levels (ε = 0.065 and σ = 3.33 × 1012 cm−2). Following gamma radiation exposure, the strain and dislocation density of AgNWs showed a non-linear decrease compared to the initial sample. The highest values for both strain and dislocation density were recorded at the 0 kGy dose (ε = 0.0064 and σ = 0.0036 × 1012cm−2). Elemental analysis (EDS) indicated that reduction processes occurred depending on the radiation dose, with the highest reduction observed in the sample irradiated at 25 kGy. Studies indicate that gamma radiation can modify the structural and physical properties of the AgNWs/GO nanocomposite.

Feasibility study of utilizing Autoclaved Aerated Concrete (AAC) waste for the production of cold bonded lightweight artificial aggregate using high volume fly ash (HVFA) binders

Autoclaved Aerated Concrete (AAC) is a popular construction material used for partitions and insulation in buildings. At the end of its service life, AAC (Autoclaved Aerated Concrete) will be demolished and subsequently disposed of in landfills, thereby creating depository problem. Therefore, the study of reutilization and recycling of AAC waste is imperative. Artificial aggregate production can be an alternative to the reutilization of AAC waste. This paper assesses the feasibility of using Autoclaved Aerated Concrete Powder (AACP) waste as a raw material for the production of artificial aggregate and investigate its physico-mechanical properties. The investigation incorporates the comparison of cement-based binder with high-volume fly ash (HVFA) binder with different replacement levels of cement. The study uses image analysis based on photographic, optical microscopic, and scanning electron microscopy (SEM) images, to describe the porosity of the aggregate. The results show that the AACP aggregates with both cement and HVFA binders meets the current industry requirement for density and cylinder crushing strength as lightweight artificial aggregate. The appropriate binder content lies between 30 % and 40 %. The best cement to fly ash ratio in HVFA binder is determined to be of 1:1 with 50 % replacement of cement with fly ash. Image analysis showed that the porosity largely affected the properties of the AACP aggregate such as density and water absorption. However, further investigation into the reducing high-water absorption of AACP aggregates is necessary to improve their overall quality.

The change rule of lipid oxidation and hydrolysis driven via water in Antarctic krill oil: Based on association colloid formation

The residual water and amphiphilic compounds such as phospholipids in bulk oil can form reverse micelles, which affect oxidative stability. In this study, the Antarctic krill oil (AKO) samples with different water contents were subjected to accelerated storage. During storage, AKO exhibited oxidative changes, manifested as increased POV, TBARS values, and volatile compound levels but decreased PUFA percentages. Meanwhile, AKO underwent hydrolysis, evidenced by decreased PC, PE, and TG contents but increased FFA contents. Moreover, the degree of lipid oxidation and hydrolysis is dose-dependent with water added. Cryogenic scanning electron microscopy imaging and micelle size distribution measurement proved the presence of reverse micelle, and their size and interfacial area improved with increased water contents. Correlation analysis suggested that lipid oxidation and hydrolysis positively correlated with the size and interfacial area of reverse micelle. Therefore, it is speculated that the oil-water interface may be the site of lipid oxidation and hydrolysis.

Effect of Zn amount on AlZn-based composite material produced by high speed mechanical alloying method

Purpose The purpose of this study is AlZn-based produced by high speed mechanical alloying method to investigate the effect of Zn amount on the composite material, Al-Zn-Mg-Cu-SiC composite material billets are obtained by sintering. Design/methodology/approach Mechanical alloying, X-ray diffraction analysis (XRD) graphics, sintering, polishing, scanning electron microscopy and energy dispersive X-ray analyzer (EDX) images and micro hardness tests were applied, respectively. Findings In the XRD analysis results, it was observed that the Al peak height decreased as the alloying time increased. When the samples sintered for 90 min are examined, it can be clearly seen that the hardness increases as the Zn ratio increases. EDX analysis results also support XRD results. Originality/value Increase in strength will require the use of thinner sheet metal and smaller rivets to achieve the same strength. This will reduce the weight of the aircraft. Weight reduction also means less fuel consumption and more economical flight. This increase in strength is a very important scientific achievement.

Exploring novel nanostructural architecture of doubly doped ceria (Ce0.85Sr0.075Sm0.075O2-δ) and barium cerate (BaCeO3) as electrolytes for low-temperature solid oxide fuel cells

This study presents the development of a composite electrolyte for use in low-temperature (300–500 °C) Solid oxide Fuel Cells, focusing on a novel nanostructural design. The electrolyte comprises co-doped ceria (Ce0.85Sr0.075Sm0.075O2-δ, DCO) and barium cerate (BaCeO3, BCO), integrated into a unique nanostructural architecture. Initially, the constituent phases of the composite DCO and BCO are synthesized using a soft-chemical route separately, followed by their integration through liquid mixing technique in various compositions (90:10, 80:20, 70:30, 60:40, 50:50) of DCO:BCO in weight ratio. The composite structure is confirmed by X-ray diffraction, and refined the structural data by Rietveld refinement indicating a structural agreement with cubic and fluorite phases of DCO and BCO, respectively. Scanning Electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) reveal a uniform distribution of two phases with fine size distribution below 50 nm. Transmission Electron microscopy (TEM) images illustrate the core-shell-like integration of the two phases. High-resolution TEM images indicate that the core consists of the DCO phase, while the shell is composed of the BCO phase. The microstructure of sintered pellets exhibits gas-tight densification, with grains dominated by the DCO phase and BCO phase dispersed along grain boundaries. The ionic conductivity of composite systems is extracted from Electrochemical impedance spectroscopy (EIS) studies, showing that DCO-BCO-40 exhibits the highest conductivity 1.132 × 10−3 Scm−1 @400 °C, which is higher than pristine DCO (0.34 × 10−4 Scm−1 @400 °C). Single cells fabricated using DCO-BCO-40 electrolytes deliver a power output of 280 mW cm−2 whereas pristine DCO showed 279 mW @500 °C. This study exhibits the potential of the core-shell-like nanostructural architecture of electrolytes in advancing Low-temperature solid oxide Fuel cell (LT-SOFC) technology and facilitating the transition toward sustainable energy systems.

Optimizing bioencapsulation of yeast cells by Aspergillus tubingensis TSIP9 and applications in bioethanol production through repeated-batch fermentation

This study aimed to immobilize yeast cells using filamentous fungi owing to a number of advantages including less chemical usage, spontaneous encapsulation, strong adhesion and biocompatibility. Filamentous fungus, Aspergillus tubingensis TSIP9 could form sphere-shape and packed pellets using either fungal fresh spores or those stored in liquid medium for 6 weeks at 4 °C. The fungus was used to immobilize yeast Saccharomyces cerevisiae FAI via adsorption and co-cultivation methods. Scanning electron microscopy images revealed that the bioencapsulated yeast cells via co-cultivation seemed to be more tightly adhered on fungal mycelia and surrounded by extracellular polymeric substances. The yeast biocapsules also exhibited higher stability and maintained their structural integrity during repeated-batch fermentation while the immobilized yeast cells by adsorption gradually degraded during their repeated uses. The bioethanol production from glucose by yeast biocapsules were in the range of 95–98 g/L with the bioethanol yield of 0.49–0.54 g-ethanol/g-consumed glucose. The yeast biocapsules could produce bioethanol well when using enzymatic hydrolysate of lignocellulosic palm waste, as alternative cheap carbon source, with the comparable bioethanol yield of 0.49 ± 0.17 g-ethanol/g-consumed glucose. The spontaneous and inter-species bioencapsulation show the perspectives as active biocatalysts with high cell retention for repeated uses.

Reevaluation of pollen differentiation in Altingiaceae: Challenges in distinguishing deciduous (Liquidambar) and evergreen (Altingia) types using multivariate statistics and machine learning

Altingiaceae, a family of woody plants, comprising evergreen Altingia and deciduous Liquidambar groups, exhibits distinct leaf morphology, yet both groups overlap in geographical range and climatic conditions. While some tropical Altingia species are confined to Myanmar, Thailand, Cambodia and India without Liquidambar, and some temperate Liquidambar species to northern China without Altingia. Their fossil pollen have significant implications in reconstructing palaeoclimate and historical biogeography, based on classification of Altingia-type and Liquidambar-type. However, the results of previous studies to differentiate pollen types of evergreen Altingia and deciduous Liquidambar were based on limited pollen specimens. Therefore pollen morphology of Altingiaceae and differentiation of above mentioned types needs reevaluation using more specimens from wider geographical range.In this study, we present new findings on Altingiaceae pollen morphology from extensive collection of specimens and reassess the diagnostic features to distinguish evergreen and deciduous types. To improve the credibility of palaeoecological and palaeoclimatic interpretations, we applied multivariate statistical analyses to pollen size, number of pores, pollen wall thickness, and size and density of ornamental elements from light microscopy (LM) and Scanning Electronic Microscope (SEM) images. Additionally, random forest classification models were applied to test the accuracy of differentiating Altingiaceae pollen types. Our results reveal significant morphological overlap between the pollen of evergreen Altingia and deciduous Liquidambar, with classification models showing limited accuracy and explainability. Thus, fossil pollen of Altingiaceae cannot be confidently classified into evergreen or deciduous types, highlighting challenges in using their pollen morphology for taxonomic classification in palaeoecological research.

Exploring the graphitization transformation mechanism of deposited carbon in molten salt electrolysis: A novel insight from molecular structure models

Molten salt electrolysis graphitization is a novel method for the electrochemical graphitization, offering significant technological advantages. Researchers have shown keen interest in preparing graphite materials through molten salt strategies. However, there is still a lack of comprehensive research methodologies at the molecular scale for the removal of heteroatoms and rearrangement of carbon atoms in different amorphous carbon conversion systems. To address the above issue, the deposited carbon (DC, a coking byproduct) was converted into graphitized material (electrolysis products, EP) through the electrochemical method in this study. By processing Transmission Electron Microscope images with Python programming, aromatic skeleton structure information was quantitatively extracted. The evolution of the structure of DC was studied using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Based on information about elemental content, aromatic skeletal structure, and heteroatom functional groups, average chemical structure models were constructed for DC and EP, and relevant chemical bond parameters were statistically analyzed. Then, the influence of the electric field on the structural transformation of amorphous carbon in molten salts was investigated. The research results show that the electric field significantly affects the graphitization transformation process of amorphous carbon in molten salts, enhancing the interaction between calcium ions and DC molecules, increasing the diffusion coefficient of particles in the system, and promoting the formation of more sp2-hybridized carbon atoms, thus forming a more compact aromatic ring network. This study provides a new research method and molecular/atomic-level insights for a deeper understanding of the mechanism of graphitization transformation of amorphous carbon.

NiMnO nanoparticle-activated carbon anodes for efficient urea oxidation and energy production in wastewater-driven direct urea fuel cells

The growing concern over urea-containing wastewater from industrial sources necessitates innovative treatment solutions that also offer sustainable energy production. In this study, a novel anode material is developed by decorating activated carbon with NiMnO nanoparticles through thermal treatment under an inert atmosphere. The resulting NiMnO NPs-decorated activated carbon was evaluated for its electrocatalytic performance in the electrooxidation of urea and its application in a direct urea fuel cell (DUFC). X-ray diffraction patterns confirmed the formation of nickel metal and Mn(II) oxide, with activated carbon showing representative peaks. Scanning electron microscopy images revealed well-dispersed nanoparticles on the activated carbon surface, corroborated by uniform elemental distribution from mapping results. Electrochemical measurements using cyclic voltammetry demonstrated that the 30 wt% MnAc sample exhibited the highest electrocatalytic activity among the tested samples (0, 5, 10, 20, 30, 40 and 50 wt% MnAc) with a maximum current density of 123 mA/cm2 at 3.0 M urea concentration and an onset potential of −0.02 V versus Ag/AgCl. Linear sweep voltammetry of the assembled DUFC showed promising open circuit potentials of 0.82 V and maximum power densities reaching 4.9 W/m2, achieved using industrial wastewater from the Egyptian Chemical Industries Company (KIMA) in Aswan, Egypt. The results highlight the efficacy of NiMnO NPs-decorated activated carbon in both urea oxidation and electrical energy generation. This study not only provides a viable method for treating urea-rich industrial wastewater but also presents a sustainable approach to energy production. The findings underscore the potential of this material for future applications in DUFCs, offering significant environmental and economic benefits.

RETRACTION: Bioreactors Based on Enzymes Encapsulated in Photoresponsive Transformable Nanotubes and Nanocoils End‐Capped with Magnetic Nanoparticles

AbstractN. Kameta, Y. Manaka, H. Akiyama, T. Shimizu, “Bioreactors Based on Enzymes Encapsulated in Photoresponsive Transformable Nanotubes and Nanocoils End‐Capped with Magnetic Nanoparticles,” Advanced Biosystems 2, no. 4 (2018): 1700214, https://doi.org/10.1002/adbi.201700214.The above article, published online on 1 February 2018 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, Naohiro Kameta, Yuichi Manaka, Haruhisa Akiyama and Toshimi Shimizu; the journal Editor‐in‐Chief, Monty Montano; and Wiley‐VCH GmbH, Weinheim. The retraction has been agreed upon following an investigation into concerns raised by National Institute of Advanced Industrial Science and Technology (AIST), and also requested by all authors due to image falsification and fabrication in electron microscopy images. In Figure 2a and 2f, where the first author falsified TEM images of irrelevant nanotubes that were developed by the authors in other studies; in Figures 2b and 2c, where the first author carelessly placed incorrect scale bars and scale values; all affecting the interpretation of the data and research results presented.

Thiamine-modified octamolybdate catalyzes solvent-free stereoselective olefin epoxidation with TBHP

Simple stirring of an acidic aqueous solution (pH=3) containing sodium molybdate and thiamine hydrochloride (VB1) at room temperature resulted in an octamolybdate-containing VB1 (MoB1) material as an efficient and cost-effective epoxidation catalyst using tert‑butyl hydroperoxide (TBHP) under solvent-free condition. The stereospecific stilbene oxidation (>99 %) observed in the presence of MoB1 can be originated from the steric hindrance of some groups on the thiamine molecule and π–π stacking interactions of its pyrimidine and/or thiazole rings with phenyl rings of stilbenes. Further olefins such as cyclooctene, indene, 1-octene, and styrenes are efficiently oxidized using MoB1/TBHP catalytic system. The catalyst is composed of two thiaminium dications (C12H18N4OS)2+ and one Mo8O264– tetraanion based on different characterization techniques and chemical compositional analyses. Field Emission Scanning Electron Microscope (FE-SEM) images shows a sheet-like nanostructure for MoB1 comprising layers with thicknesses ranging from 50 to 500 nm. It exhibits a heterogeneous nature in catalysis evidenced by hot filtration test and ICP-OES analysis. X-ray photoelectron spectroscopy (XPS) indicates minor contributions of Mo in the oxidation states +V and +IV in addition to MoVI attributed to partial electron transfer from VB1 to Mo8O264–. The scavenging experiments support the presence of radical species during catalysis, while, they do not damage the structural integrity of the MoB1 catalyst based on the recycling experiments and FT-IR spectra.

Enhanced chitosan and Carboxymethylcellulose scaffolds with natural fiber reinforcement for hernia repair meshes

AbstractChitosan (Chi) and carboxymethylcellulose (CMC) scaffolds, with and without reinforcement by Luffa cylindrica (Lc) or Asclepias curassavica (Ac), were synthesized to evaluate their potential application as hernia repair meshes. These meshes are crucial as they provide structural support to weakened tissues, reducing the risk of hernia recurrence and promoting faster recovery. They improve patient outcomes by enhancing the durability and effectiveness of hernia repairs. Chi scaffolds exhibited lower porosity compared to CMC scaffolds, with fiber inclusion enhancing porosity. The CMC4‐Ac scaffold demonstrated the highest porosity at 67.2%, which is crucial for supporting cell growth and tissue regeneration. All scaffolds exhibited exceptional hydration levels, which is vital for cell growth. Scanning electron microscope (SEM) images revealed open pores in the CMC4 scaffolds, which enhances tissue formation. Tensile strength tests indicated that all scaffolds surpassed the minimum requirements, with CMC4‐Ac standing out for its exceptional properties. CMC scaffolds showed greater degradation, which was mitigated by fiber reinforcement. Chi scaffolds absorbed more Croton draco extract (Cdext) but exhibited lower release rates compared to CMC scaffolds. No hemolytic and non‐cytotoxicity effects were observed. CMC4‐Ac emerged as the most promising scaffold due to its superior properties, making it suitable for hernia repair meshes.

Evaluation of the antibacterial activity of selenium nanoparticles and those conjugated with lysozyme against Bacillus cereus spiked in pasteurized skim milk

Selenium nanoparticles (SeNPs) and SeNPs conjugated with lysozyme (SeNPs-lysozyme) were synthesized via sodium selenite reduction with ascorbic acid and polysorbate-80 stabilization. These were physiochemically characterized to impart antibacterial properties. X-ray diffraction analysis (XRD) revealed that both formulations had hexagonal crystalline structures. Fourier transform infrared (FT-IR) confirmed the successful conjugation of lysozyme to SeNPs through the emergence of amine peaks at 1542 cm−1. Dynamic light scattering (DLS) showed lysozyme conjugation increased nanoparticle size from 76.6 to 92.4 nm and charge from − 12.6 to + 17.6 mV. Transmission electron microscopy (TEM) images confirmed that spherical morphologies and size increased from 73–79 nm for SeNPs to 84–98 nm for SeNPs-lysozyme after lysozyme capping. Both formulations exhibited identical minimum inhibitory concentrations (MIC) of 125 μg/mL. However, lysozyme conjugation reduced SeNPs cytotoxicity by 2.4-fold based on IC50 values from an MTT (Thiazolyl Blue Tetrazolium Bromide) assay. When tested in phosphate-buffered saline (PBS), SeNPs and SeNPs-lysozyme fully inhibited Bacillus cereus (B. cereus) proliferation up to 6 log10 CFU/mL inoculums over 24 h of incubation. However, at (7 log10 CFU/mL) inoculum, only partial inhibition occurred, with (2.5 ± 0.3 log10 CFU/mL) growth still detected for SeNPs and (2.2 ± 0.2 log10 CFU/mL) for SeNPs-lysozyme. At all inoculum levels (5, 6, and 7) log10 CFU/mL, B. cereus grew a lot in milk (more than 8 log10 CFU/mL). This was probably because SeNPs or SeNPs-lysozyme tend to aggregate around milk components, making them less effective.

Effects of NaCl/KCl ratios on structural and properties changes in soy‐potato protein mixed gel

SummaryTo reduce the sodium salt content in protein gel‐based foods, this study investigated the effects of different Na‐K ratios on the gelation properties and structural changes of soy protein isolate (SPI) and potato protein isolate (PPI) composite gels. The results showed that the composite gel properties were further enhanced with increasing Na‐K ratio in the SPI/PPI gel system. Specifically, when the Na‐K ratio was 1:1, the SPI/PPI composite gel exhibited the highest gel strength, gel elasticity, WHC, storage modulus (G′), and β‐sheet content, whereas the α‐helix content and β‐turn content were the lowest. Scanning electron microscopy images revealed a dense and uniform network structure of the composite gel. The addition of low concentrations of Na+ and K+ improved the network structure and water‐holding capacity of the SPI/PPI gel during the heat‐induced gelation process. However, excessively high Na‐K ratios weakened the gel properties.

Temperature induced fast-setting of cement based mineral-impregnated carbon-fiber reinforcements for durable and lightweight construction with textile-reinforced concrete

Developing durable and sustainable mineral-impregnated carbon-fiber (MCF) reinforcement system is today an effective measure to solve common service issues of conventional steel or FRP reinforcement in building sector. This study introduces a novel methodology for the design and realization of fast-setting cement based MCF reinforcements via targeted thermal activation. The process involves impregnating continuous yarns with a micro-sized particle cement suspension utilizing custom-built manufacturing equipment. Subsequently, the impregnated yarns undergo controlled heating at moderate temperatures to accelerate the cure process and strength development. Flexural and tensile performance of the MCFs exhibits progressive improvements with longer curing durations (from 2 to 20 h) and higher temperatures (from 40 °C to 60 °C). Enhanced mechanical properties are attributed to advanced hydration reactions and microstructural densification, as proven by thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), scanning electron microscopy, isothermal calorimetry and micro-computed tomography (μCT). When heating at 60 °C for 20 h, as-produced MCFs demonstrate optimal tensile strength of 2747 MPa and flexural strength of 482 MPa, with exceptional bond with concrete substrate, comparable to conventional FRPs. The proposed post-treatment shows promising potential for significantly enhancing the flexibility of mineral matrix composites, making them suitable for a wide range of industrial and field applications.

Dilated multilevel fused network for virus classification using transmission electron microscopy images

Previous studies have demonstrated significant performance in the field of virus classification; however, they focused on the classification of a small number of virus classes, with a maximum of 16 classes. To address this limitation, this study aims to create a deep learning-based network that outperforms the state-of-the-art (SOTA) models for the classification of 22 different virus classes with the fewest possible trainable parameters. We introduce an automatic identification system for virus classes based on our classification-driven retrieval framework. The proposed dilated multilevel fused network (DMLF-Net) utilizes the multilevel feature fusion concept within a network to exploit more abstract features for microscopic data analysis. A multi-stage training strategy was applied to achieve optimal model convergence without overfitting the training data.We evaluated the performance of the DMLF-Net on three open databases including two virus datasets and one bacteria species dataset. The results demonstrated an accuracy of 89.89%, a weighted harmonic mean of precision and recall (F1-score) of 83.39%, and an area under the curve (AUC) of 92.50% for the 1st virus dataset. For the 2nd virus dataset, the accuracy was 80.70%, the F1-score was 81.20%, and the AUC was 86.20%. For the 3rd bacteria species dataset, the accuracy was 95.93% and the F1-score was 96.24%. DMLF-Net outperforms SOTA methods in terms of classification accuracy while utilizing nearly 5.3 times fewer trainable parameters (25.5 million) compared to the second-best model, visual geometry group (VGG)16 (134.3 million).

Enhanced hypersensitive (5D0→7F2) transition characteristics of Eu3+ doped β-Ga2O3 microrods

Exploring and realizing the luminescence characteristics of rare earth metal (RE) ions doped gallium oxide (Ga2O3) is crucial for developing optoelectronic device applications. The current research used the solid-state reaction approach to synthesize Ga2O3 microrods doped with various europium (Eu3+) concentrations (0.1, 0.2, 0.3, 0.5, 0.75, and 1 mol). X-ray diffraction (XRD) and Raman spectral analyses confirm the monoclinic structure of β-Ga2O3. The intensity of the Raman phonon modes decreased and a peak shift was observed for Eu:β-Ga2O3. The electron microscopy (SEM, TEM) images depicted a nearly uniform distribution of microrods for undoped and Eu:β-Ga2O3 samples. The interplanar distance (d = 0.290 nm, 0.561 nm, and 0.433 nm), from HR-TEM images, corresponding to (0 0 4), (1 0 0), and (1 0 2) crystallographic orientations confirm the monoclinic structure of β-Ga2O3. The elemental mapping images showed a nearly homogeneous Ga, O, and Eu distribution. The UV–visible diffuse reflectance spectroscopy (UV-DRS) showed a notable reduction in the bandgap as the Eu3+ concentration increased. The emission spectra of Eu: β-Ga2O3 microrods showed a narrow red emission at 612 nm (5D0 → 7F2), which relates to the 5D0 → 7Fj (j = 0, 1, 2, 3) energy level arising from an intra-4f transition of Eu3+ ions upon 394 and 465 nm excitation. The red emission was found to increase with Eu content up to 0.5 mol.%. A quenching of emission due to the multipole–multipole interactions was obtained beyond 0.5 mol.% of Eu. The absolute quantum yield (η) calculated for Eu: β-Ga2O3 (0.5 mol.%) was 3.82 %. The luminescence decay curve using the bi-exponential fit and the average lifetime (τ) of the Eu: β-Ga2O3 (0.5 mol.%) was found to be ∼0.172 ms. CIE chromaticity and correlated color temperature analyses of Eu:β-Ga2O3 microrods yielded a red emission with a superior color purity (93 %). The obtained results suggest that Eu:β-Ga2O3 (0.5 wt.%) microrods could be one of the potential candidates for red light sources.

New evidence of syn-eruptive magma-carbonate interaction: the case study of the Pomici di Avellino eruption at Somma-Vesuvius (Italy)

Calcareous lithics are commonly found within the products of some explosive eruptions of Somma-Vesuvius. The pumice fragments from the final phase of the Plinian fallout event of the Pomici di Avellino eruption contain abundant calcareous xenoliths. Previous work on that eruption, including numerical simulations, suggested that the release of CO2 from the entrapment of carbonates may have prolonged the magmatic phase of the eruption by maintaining sufficient driving pressure in the feeding dike. The texture and thermo-metamorphic reactions of carbonate xenolith-bearing pumice fragments of the Pomici di Avellino eruption are analyzed through petrography, scanning electron microscope images, energy dispersive spectrometer analyses, and micro-computed X-ray tomography to deduce the behavior of short-term carbonate-magma interaction and its contribution to the eruption dynamics. Results show that calcareous xenoliths experienced short-term magma-carbonate interaction, which took place in three steps: (i) entrainment, i.e., the mechanical process of carbonate xenoliths entrapment into a magma; (ii) decarbonation, related to high-temperature decomposition reaction of the xenoliths; and (iii) digestion or dissolution of the incorporated calcareous xenoliths into the melt with diffusion of Ca and Mg. The CO2 released during the syn-eruptive decarbonation process thus provided extra volatiles to the rising magma, which may have maintained magma buoyancy longer than expected if only magmatic volatiles were involved in the eruption.

Photo-induced time-dependent controllable wettability of dual-responsive multi-functional electrospun MXene/polymer fibers

Switchable wettability potential in smart fibers is of paramount importance in various applications. Light-induced controllable changes in surface wettability have a significant role in this area. Herein, smart waterborne homopolymer, functional copolymer with different polarity and flexibility, and multi-functional terpolymer particles containing a time-dependent dual-responsive acrylated spiropyran, as a polymerizable monomer, were successfully synthesized through eco-friendly single-step emulsifier-free emulsion polymerization. Presence of 10 wt% of butyl acrylate and dimethylaminoethyl methacrylate relative to methylmethacrylate as functional comonomers decreased the Tg of the samples almost 20 ℃ and increased their polarity. The optical properties of the particles were investigated, and the UV–vis and fluorescence spectroscopy results showed that not only polarity and flexibility of the polymer chains may have a positive effect on improving the optical properties, but also the simultaneous presence of functional groups has a synergistic effect. The smart polymer particles with flexibility and polarity features exhibited higher absorption and emission compared to other samples. Inspired by these findings, multi-functional smart polymer fibers were prepared using the electrospinning method. The smart multi-functional electrospun fibers containing few-layer Ti3C2 MXenes were synthesized to improve the fibers’ properties and change the surface wettability due to the hydrophilic functional groups of MXene. Field-emission scanning electron microscopy images displayed the successful preparation of few-layer MXenes. Smooth and bead-free fibers with bright red fluorescence emission under UV irradiation were shown using fluorescence microscopy. The study on the surface wettability of fibers revealed that UV and visible light irradiation induced reversible time-dependent changes in the wettability of the smart multi-functional MXene/polymer electrospun fibers from hydrophobic to hydrophilic, reaching a water contact angle of 10° from an initial water contact angle of 100° under UV light and also changing to superhydrophilic state with passing time. Upon visible light exposure, the fibers returned to their original state. Furthermore, the fibers demonstrated a high stability over five alternating cycles of UV and visible light irradiation. This study shows that the fabrication of time-dependent smart fibers, utilizing the flexibility and polarity in the presence of MXenes, significantly improves and controls surface wettability changes. The outstanding dynamically photo-switchable wettability of these fibers may offer exciting opportunities in various applications, especially in the separation of oil from water contaminants.