Electron Microscopy Studies Research Articles

Tunable Charge Transport Using Heterocycles-Flanked Alkoxyphenanthrenes for High-Performing OFETs.

A series of new heterocycles-flanked alkoxyphenanthrenes with D'-D-D' and A-D-A architecture was synthesized for high-performance solution-processable p-channel, n-channel, and ambipolar organic field-effect transistors. The impact of electron-donating and -accepting abilities of the sulfur- and nitrogen-containing heteroaromatics on photophysical, electrochemical, and semiconducting properties was analyzed. The presence of heteroaryl rings improves the extended conjugation, two-dimensional lattices of π-π stacks, and increased molecular interaction of the functionalized phenanthrenes (PN) to allow better self-assembly. The electronically dynamic PN self-assembles into continuous microdomains, forming percolation channels for holes, electrons, or both reliant on functionalization. The low-lying LUMO levels of the compounds enabled ambipolar transport and reduced energy levels for charge injections. Spin-coated devices fabricated using functionalized PN with sulfur-containing heteroaryl substituted PN exhibited the highest hole mobility of 0.85 cm2/(V s) with 108 on/off current ratio. Compounds with A-D-A architecture showed n-channel/ambipolar charge transport, especially napthalimide acceptor substituted PN exhibited n-channel electron mobility of 0.78 cm2/(V s) and an on/off ratio of 106. X-ray diffraction and scanning electron microscopy studies further delineate the impact of efficient packing in the film. Quantum chemistry calculations combined with Marcus-Hush electron transfer theory interpret the transport parameters, and heteroatoms are established to impact the charge mobility intensely.

Tailoring of magnetic phase: Co-doped SiC thin films grown by RF sputtering

In the present work, we investigate the influence of cobalt (Co) doping on the structural and magnetic properties of cobalt-doped silicon carbide (Co-SiC) thin films. The films were fabricated using DC/RF magnetron sputtering technique on Si (100) substrates at a temperature of 1200°C, with varying Co concentrations ranging from 5 to 16 at. (at%. X-ray diffraction (XRD) analysis unveiled the co-existence of CoSi2 and SiC phases in all the thin films. Surface morphological study through atomic force microscopy (AFM) revealed the densely packed nature of the films. Field emission scanning electron microscopy (FE-SEM) study showed that particles are uniformly distributed at the surface of the substrate. According to UV measurements, the films have high transmittance in the visible range, and as Co concentration rises, transmittance decreases. A magnetic phase transition from superparamagnetic to ferromagnetic behavior occurred with Co content surpassing 8 at% in the SiC thin films. Moreover, an increase in coercivity was observed from 38 Oe to 316 Oe as the doping concentration increased from 10 to 16 at%. This study represents an exploration into the induction of ferromagnetism through moderate Co doping in SiC thin films.

Effect of pH on the microstructure and antibacterial properties of MgO nanoparticles by microwave-assisted solution combustion

The application of magnesium oxide (MgO) nanoparticles as a candidate material for antibacterial purposes has been limited by their relatively low antibacterial activity. In this study, antibacterial MgO nanoparticles were synthesised in one step using magnesium nitrate and citric acid as raw materials using an economical and environmentally friendly microwave-assisted solution combustion approach, while the effect of the pH of the reaction system (2, 4, and 7) on the structure and antimicrobial properties of the synthesised MgO nanoparticles was investigated. X-ray diffraction (XRD) analysis demonstrated the formation of cubic-phase MgO nanoparticles, and electron microscopy studies confirmed that MgO nanoparticles synthesised at a precursor solution pH of 4 had uniform size distribution with a small microcrystalline size (∼19 nm) and spherical granular morphology. In addition, the results of the plate colony counting method showed that the antibacterial rate of MgO-4 against Gram-negative Escherichia coli (106 CFU/mL) at a sample concentration of 100 μg/mL was as high as 99.86 %, which showed excellent antibacterial performance. These findings provide valuable insights into how to increase the degree of oxygen adsorption on the sample surface to participate in the reaction, as well as a potential method for constructing nanomaterials with high antimicrobial activity.

SYNTHESIS AND PHYSICO-CHEMICAL PROPERTIES OF A NEW COMPLEX FERRITE

The article discusses the synthesis of new complex ferrite, radiographic and electron microscopic studies. The phase of complex ferrites was synthesized by the method of high-temperature sol-gel synthesis. For the first time, the structure of CrKFe2O5 Composite ferrite was studied by X-ray phase analysis and scanning electron microscope methods, the syngony type, elementary cell parameters, radiographic and pycnometric densities, and elemental analysis were determined. A comparative analysis of the relationship between the parameters of the Crystal cell of primary substances and the parameters of the obtained complex ferrite Crystal cell was carried out. Micro-samples were taken from different parts of the crystallite obtained through a scanning electron microscope, the elemental composition of the crystals was analyzed, and the general type of layer of the complex ferrite surface was demonstrated. As a result, the fact that the compound consists of two phases, the clarity of its construction was determined by the topography and chemical composition of the compound. As a result, it was found that the newly synthesized complex ferrite corresponds to the Formula CrKFe2O5. The particle size of the compounds formed is large (between 200 μm, 20.0 μm, 5.00 μm and 2.00 μm).

Approach to Design Sustainable Alkali-Activated Slag Recycled Aggregate Concrete: Mechanical and Microstructural Characterization

There is a steep increase in demand for concrete as the need for infrastructure is increasing with a rapid increase in urbanization. Consequently, there has been a surging demand for cement across the globe. By using alkaline concrete activated with ground granulated blast furnace slag (GGBS), cement usage can be eliminated in concrete, which addresses the issue of CO2 emissions concerned with the cement manufacturing process and promotes the use of industrial by-products as sustainable building materials. The current study focuses on proposing a methodology to design sustainable GGBS-based alkali-activated concrete incorporated with 100% coarse recycled coarse aggregates (RCA) recovered from construction and demolition (C&D), for various strengths by optimizing the mix proportions and verifying the same through experiments. From the current study, it is evident that this mix design procedure can be adopted to design alkali-activated slag recycled aggregate concrete (AASRAC) mixes for strengths ranging from 44MPa to 85MPa. The optimum values of alkalinity factor (λ) and NaOH concentration (M) i.e., 1.5 and 12, have a significant role in the development of high strengths which is attributed to the formation of hydrotalcite. Micrographs captured using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) studies reveal that the alkaline binders promote the development of a denser and stronger interfacial transition zone (ITZ) that enhances the strength of lower AA/B concretes at the microstructural level as Ca/Si ratio is higher for lower AA/B concretes. Global warming potential (GWP) analysis reveals that the alkali-activated concretes have significantly lower GWP compared to conventional OPC-based concrete by approximately 2.5 times. The mix-design chart proposed in this study may pave the way to designing structural grade AASRAC with enhanced performance for the desired strength, which may find its application in fast-track construction and manufacturing of prefabricated elements.

Enhancement of dielectric constant in Sm:Zr co-doped HfO2 films synthesized by cost-effective method

Sm, Zr co-doped HfO2 films were deposited on a p-type silicon wafer using a cost-effective spin coating method. The influence of Sm, Zr co-doping concentration variation on structural, compositional, morphological, and electrical properties was examined. The dominance of the orthorhombic phase (o-phase) in comparison to the monoclinic phase was noted to rise with the simultaneous increment of Sm doping concentration and decrement of Zr concentration. A decrease in oxygen vacancies was noted for all the Sm, Zr co-doped HfO2 films from XPS results. Nonporous and uniform distribution of grains was observed from Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM) studies. Electrical studies of MOS capacitors based on Sm, Zr co-doped HfO2 films revealed a low leakage current. C-V studies exhibited an increment of dielectric constant and a decrement of interface trap densities. Further, to obtain insights into the microscopic features of Sm, Zr co-doped films, impedance and modulus studies have been performed. The obtained results imply the potential of tuning Sm, Zr co-doping concentrations in HfO2 towards stabilization of the orthorhombic phase and to enhance the dielectric constant of the films.

Characterization and functional insights of the novel RC-type plasmid pAnox1 from Anoxybacillus gonensis 05S15

The plasmid pAnox1, isolated from Anoxybacillus gonensis 05S15, was sequenced and characterized as a circular, double-stranded DNA molecule of 1592 base pairs with a GC content of 40.01 %. Despite its cryptic nature and small genome, bioinformatic analyses identified conserved motifs associated with replication-related proteins, though BLAST searches revealed no significant homology with other plasmids. The plasmid genome contains five putative Open Reading Frames (ORFs), four palindromic sequences, and two direct repeats on both strands, suggesting regulatory roles. Electron microscopy and Southern hybridization studies confirmed that pAnox1 follows a Rolling Circle (RC) replication mode. The study further demonstrated that the plasmid encodes three distinct transcripts: ORF-1 and ORF-3 are oriented in the same direction, while ORF-5 is on the opposite strand. RACE and LACE analyses revealed transcript lengths of 903 bp for ORF1, 499 bp for ORF3, and 211 bp for ORF5. Quantitative real-time PCR estimated the relative copy number of pAnox1 at 127 ± 2 copies per chromosomal equivalent. This novel RC-type plasmid in the Anoxybacillus genome holds promise as a cloning and expression vector for biotechnological applications and in vivo protein engineering.

A Study on Cu Decorated Anodic TiO2 Nanotubes for Non-Enzymatic Glucose Sensing and Photoelectrochemical Water Splitting Application

Free-standing, surface-modified TiO2 nanotubes(TNTs) decorated with copper nanostructures have been extensively studied as promising materials for their application in biosensing and photo-electrochemical splitting of water. Here, the TNTs are prepared by electrochemical anodization followed by modification with copper nanostructures via UV-assisted photo-reduction technique. Field-emission scanning electron microscopy and X-ray diffraction studies confirmed the structural and morphological properties of the TNTs, along with their tubular architecture and mixed-phase composition of Anatase-Rutile. Energy-dispersive spectroscopic analysis verified the successful deposition of copper. Diffuse reflectance spectroscopy revealed an electronic band gap of 3.2 eV. The copper-modified TNTs showed an enhanced sensitivity in the sensing of glucose to the tune of 0.52 mA mM−1 cm−2 with a high linear range of 0.5 to 7 mM and showed superior selectivity against interferents. It was found that the modified TNTs exhibited a higher photocurrent response of 1.09 mA cm−2 compared with pristine TNTs (0.69 mA cm−2). These findings indicate the promising potential of copper-modified TNTs for continuous glucose monitoring and photo-electrochemical applications.

The possible protective role of glucosamine versus zoledronic acid on osteopenic effect of pantoprazole in adult male albino rats

Background Osteopenia is an asymptomatic condition till fragility fractures occur and may be linked to prolonged use of pantoprazole. Aim To determine osteopenic effect of long-term use of pantoprazole and study the possible protective role of glucosamine versus zoledronic acid on this effect in adult male albino rats. Patient and methods A total of 60 rats were divided equally into six groups; group I subdivided equally into IA received no treatment and IB received normal saline. Group II received glucosamine. Group III received zoledronic acid. Group IV received pantoprazole. Group V received pantoprazole and glucosamine. Group VI received pantoprazole and zoledronic acid. After 12 weeks, the left femurs were subjected to radiography and measured bone mineral density from the proximal end (neck). The right proximal ends of femurs were processed for histological, immunohistochemical, and scanning electron microscopic studies. Results Groups V and VI showed restoration of normal trabecular histology with a highly significant increase in trabecular thickness and a highly significant decrease in inter-trabecular spaces and mean area% of osteopontin compared with group IV. However, it seemed that group V had a more anabolic effect revealed by significant increase in bone mineral density, Z-score, and mean area% of osteocalcin compared with group VI. Conclusion Long-term use of pantoprazole led to osteopenia. Concomitant use of either glucosamine or zoledronic acid with pantoprazole reduced the severity of trabecular damage induced by pantoprazole. However, it seemed that glucosamine exerted a more anabolic effect than zoledronic acid.

Evaluation of Marginal Adaptation of SDR Plus, Fiber-Reinforced and Nanofilled Composites in Endodontically Treated Teeth: A Scanning Electron Microscopic Study.

Endodontically treated teeth (ETT) undergo structural changes, including a reduction in water content and loss of dentin elasticity, which can compromise their mechanical properties. One critical factor influencing the long-term prognosis of a restored ETT is the marginal adaptation of the restorative material. The present study compared the marginal adaptability of Smart Dentin Replacement (SDR) Plus, fiber-reinforced, and nanofilled composites in ETT using scanning electron microscopy (SEM). Cavities were made in 30 recently extracted maxillary premolars distributed into three experimental groups depending on the restorative material used: group 1 as SDR Plus (Dentsply Sirona, Charlotte, North Carolina, USA), group 2 as fiber-reinforced composite (EverX, GC Corp., Tokyo, Japan), and supra nanofilled composite (Estelite Sigma Quick, Tokuyama Dental Corp., Tokyo, Japan). Standardized access openings were performed, and endodontic treatment was completed in all teeth. Specific composite restoration techniques were applied according to the manufacturer's instructions. After thermocycling for 30 days, the restored teeth were sectioned and viewed using SEM (Labindia Instruments Pvt. Ltd., Maharashtra, India) to measure the width of the marginal gap. The data were analyzed using statistical software. The mean marginal gap width varied significantly among the groups. Group 1 had a lower mean marginal gap of 2.99 μm, group 2 exhibited the highest mean marginal gap of 10.24 μm, and group 3 had a mean marginal gap of 5.51 μm. Overall, group 2 consistently showed significantly larger marginal gaps than the other groups. Within the limitations of this study, SDR Plus demonstrated better marginal adaptation than fiber-reinforced and supra-nanofilled resins in the coronal restoration of ETT. Fiber-reinforced composites demonstrated the maximum marginal gap, followed by nanofilled composites. Thus, SDR Plus may be recommended as a suitable restorative material to enhance the longevity and success of endodontic treatments.

Biocompatibility, antimicrobial efficacy, and therapeutic potential of cobalt carbonate nanoparticles in wound healing, sex hormones, and metabolic regulation in diabetic albino mice

Nanotechnology enables the manipulation of materials at the nanoscale, offering innovative solutions in various fields. Nanoparticles, with their small size and unique properties, have significant applications in the biomedical filed. The current study was designed to assess the biological applications of self-synthesized cobalt carbonate (CoCO3) nanoparticles. The crystalline structure and chemical composition of the CoCO3-NPs were confirmed by SEM, XRD, and FTIR techniques. We observed the 16.58 nm size of novelly synthesized CoCO3 NPS. The scanning electron microscope study confirmed a uniform cubic spinel structure. The biocompatibility and antimicrobial activity were checked in an invitro setup. We exposed albino mice to these synthesized NPs to study wound healing and metabolic effects. The results of biocompatibility analysis indicated hemolytic activity in a dose-dependent way, which showed no cytotoxic effect except at a higher concentration. Furthermore, the results showed enhanced wound healing processes in CoCO3-NP-treated albino mice as compared to the control group. CoCO3-NPs have considerable effect on the thyroid hormone and insulin levels in albino mice. The levels of T3, T4, and insulin were increased in a dose-dependent manner. Interactions between CoCO3-NPs and thyroxine and insulin were confirmed through molecular docking. We confirmed the antimicrobial efficiency of the nanoparticles using MIC values and zones of inhibition against Staphylococcus haemolyticus and Staphylococcus aureus. Despite their concentration-dependent biocompatibility concerns, the results are promising, as CoCO3-NPs hold potential for use in medical practice, particularly in advanced wound management and microbe inhibition.

3-Alkoxy-1-Benzyl-5-Nitroindazole Derivatives Are Potent Antileishmanial Compounds.

Indazoles have previously been identified as molecules with antiprotozoal activity. In this study, we evaluate the in vitro activity of thirteen 3-alkoxy-1-benzyl-5-nitroindazole derivatives (series D) against L. amazonensis, L. infantum, and L. mexicana. In vitro, cytotoxicity against mouse peritoneal macrophages and growth inhibitory activity in promastigotes were evaluated for all compounds, and those showing adequate activity and selectivity were tested against intracellular amastigotes. Transmission and scanning electron microscopy were employed to study the effects of 3-alkoxy-1-benzyl-5-nitroindazole and 2-benzyl-5-nitroindazolin-3-one derivatives on promastigotes of L. amazonensis. Compounds NV6 and NV8 were active in the two life stages of the three species, with the latter showing the best indicators of activity and selectivity. 3-alkoxy-1-benzyl-5-nitroindazole derivatives (series D) showed in vitro activity comparable to that of amphotericin B against the promastigote stage of Leishmania spp. Two compounds were also found to be active the amastigote stage. Electron microscopy studies confirmed the antileishmanial activity of the indazole derivatives studied and support future research on this family of compounds as antileishmanial agents.

A refined plan-view specimen preparation technique for high-quality electron microscopy studies of epitaxially grown atomically thin 2D layers

The structural studies of two-dimensional (2D) van der Waals heterostructures and understanding of their relationship with the orientation of crystalline substrates using transmission electron microscopy (TEM) presents a challenge in developing an easy-to-use plan-view specimen preparation technique. In this report, we introduce a simple approach for high-quality plan-view specimen preparation utilizing a dual beam system comprising focused ion beam and scanning electron microscopy.To protect the atomically thin 2D heterostructure during the preparation process, we employ an epoxy layer. This layer serves as a protective barrier and enables the creation of a TEM specimen comprising a thin substrate fragment with an overgrown 2D structure covered by a thin, electron-transparent epoxy layer. The coexistence of both 2D layers and substrate is essential for investigating the relative crystallographic orientations between the grown 2D structures and the substrates. The thickness of the specimen is monitored using low-voltage scanning electron microscopy.We apply this technique to prepare plan-view specimens of 2D germanium-antimony-telluride (GST) on Si and hexagonal boron nitride (h-BN)/epitaxial graphene (EG) heterostructures grown on 6H-SiC substrates. The grain-like atomic structure observed in the 2.2 nm thick GST layer on Si substrate provides evidence of the mosaicity of GST during the early stages of epitaxial growth. H-BN/EG on 6H-SiC structural studies indicate a rotation of h-BN/EG around the 6H-SiC[0001] axis by an angle of 30°. The observed BN particles with sizes in the nanometer range on top of the sample have the wurtzite lattice type and random orientation.The developed specimen preparation technique offers a powerful tool for TEM studies of atomically thin layers on crystals. Its simplicity and ability to provide valuable insights into the in-plane relationships between 2D structures and crystalline substrates make it a promising complement to grazing incident X-ray diffraction.

Recent deep-sea nematodes and agglutinated foraminifera select specific grains and bioclasts from their environments: Ecological implications

The high-latitude regions are known for a diverse array of benthic meiofauna, yet our understanding of these communities remains limited, particularly in the deep ocean. This study aims to assess the variability and adaptation of nematodes and agglutinated foraminifera in the modern sediments of the Southern Pacific Ocean at >3500 m water depth. Seawater and sediment slurry from the first piston cores (i.e., mudline samples) from International Ocean Discovery Program Sites U1539, U1540, U1541, and U1543 were analyzed for Rose Bengal stained nematode and agglutinated benthic foraminifera. During the microscopic study seven nematode specimens belonging to the genus Desmoscolex, with 16–17, 36 or 38 main rings were found. Scanning electron microscopy study suggest that one morphotype with 17 main rings used only coccoliths of the species Calcidiscus leptoporus while the other specimens used fine-grained siliciclastic material on their concretion ring. Besides nematodes, a few benthic agglutinated foraminifera specimens exclusively used a single species of planktic foraminifera (Globoconella inflata) and/or robust coccoliths, in addition to other fine-grained siliciclastic material, for their test construction. These patterns appear to be highly selective. Specimens of the same benthic nematode Desmoscolex genus and agglutinated foraminifera that have diverse grain types show that these specimens can adapt to their environments, choose specific grains as per their preference, and have no relationship with the grain/particle abundance. This study of Desmoscolex and agglutinated foraminifera species suggests low to moderate organic matter flux and increased ventilation in the abyssal depth of the Southern Pacific Ocean.

Benzofuran and Benzo[b]thiophene-2-Carboxamide Derivatives as Modulators of Amyloid Beta (Aβ42) Aggregation.

A group of N-phenylbenzofuran-2-carboxamide and N-phenylbenzo[b]thiophene-2-carboxamide derivatives were designed and synthesized as a novel class of Aβ42 aggregation modulators. In the thioflavin-T based fluorescence aggregation kinetics study, compounds 4 a, 4 b, 5 a and 5 b possessing a methoxyphenol pharmacophore were able to demonstrate concentration dependent inhibition of Aβ42 aggregation with maximum inhibition of 54 % observed for compound 4 b. In contrast, incorporation of a 4-methoxyphenyl ring in compounds 4 d and 5 d led to a significant increase in Aβ42 fibrillogenesis demonstrating their ability to accelerate Aβ42 aggregation. Compound 4 d exhibited 2.7-fold increase in Aβ42 fibrillogenesis when tested at the maximum concentration of 25 μM. These results were further confirmed by electron microscopy studies which demonstrates the ability of compounds 4 a, 4 b, 4 d, 5 a, 5 b and 5 d to modulate Aβ42 fibrillogenesis. Compounds 5 a and 5 b provided significant neuroprotection to mouse hippocampal neuronal HT22 cells against Aβ42-induced cytotoxicity. Molecular docking studies suggest that the orientation of the bicyclic aromatic rings (either benzofuran or benzo[b]thiophene) plays a major role in moderating their ability to either inhibit or accelerate Aβ42 aggregation. Our findings support the application of these novel derivatives as pharmacological tools to study the mechanisms of Aβ42 aggregation.

Scanning Electron Microscopy Based Morphology of Papaya Mealybug [Paracoccus marginatus Williams and Granara De Wilink (Hemiptera: Pseudococcidae)] on Mulberry Plant of Assam, India

A scanning electron microscopy (SEM) study was conducted on the external morphology of the adult female Papaya mealybug, Paracoccous marginatus Willam and Granara de Willink. This study aimed to enhance the understanding of the external morphology and wax-secreting pores of the papaya mealybug through SEM examination. The ultrastructure of the antenna, stylet fascicle, legs, cerarii, vulva, and wax-secreting pores was carefully examined. Despite the time-consuming and expensive nature of preparing specimens for SEM, the detailed information obtained is valuable for resolving challenging aspects of papaya mealybug taxonomy and enhancing our understanding of the role of wax in their biology.

A detailed characterization study of Ni/CeO2 catalysts identifies Ni availability as the primary factor affecting CO2 methanation performance

The structure of a catalyst has a strong impact on its performance. Here we investigate the physicochemical properties of Ni/CeO2 in an attempt to draw structure–activity relationships for CO2 methanation. A combination of characterisation methods (X-ray diffraction (XRD), 4D Scanning Transmission Electron Microscopy (4D-STEM), CO chemisorption and oxygen storage capacity study etc.) clearly demonstrates the effect of Ni crystallite size, Ni availability (i.e. catalytically accessible Ni) and oxygen vacancies at the Ni-CeO2 interface in Ni/CeO2 during CO2 methanation. Among them, the role of exposed Ni active sites is highlighted, and two possible optimisation schemes i.e. changing the support calcination temperature and the final calcination atmosphere are proposed to obtain a better dispersal of Ni NPs (nanoparticles) on CeO2. Both modification methods do not affect the reaction route, and the activity differences of Ni/CeO2 can be explained by the various hydrogenation rate of formate species, as confirmed by in situ diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS) measurements.

Tracing magmatic footprints: Influence of a CO2-rich melt on the mineral assemblage of the San José del Guaviare Syenite, SE Colombia

A combined optical and electron microscopy (SEM, EDS, and EPMA) study was conducted on ten rock samples from the Proterozoic San José del Guaviare Syenite (SJGS), southeastern Colombia, to utilize minor and trace minerals in interpreting the magmatic evolution of these silica undersaturated rocks. The major minerals of the sampled syenites are nepheline, Fe-rich clinopyroxene, amphibole, alkali feldspar, and biotite. The minor minerals are titanite, calcite, cancrinite, and sodalite. Trace minerals are the niobium- or rare earth element-rich minerals pyrochlore, columbite, euxenite, britholite, ancylite-Ce and wöhlerite. Apatite, rhodochrosite, strontianite, fluorite, zircon, magnetite, ilmenite, and pyrite occur as traces as well. Crystallization started with primary (magmatic) calcite and Nb-rich minerals pyrochlore, columbite, euxenite, and a first generation of apatite, which occur as inclusions in foids, feldspars, and Fe-rich clinopyroxenes. Calcite is enriched in light rare earth elements and Sr, with low Mg concentrations, while primary apatite has high Sr concentrations. Both minerals have a composition typical for minerals crystallized in carbonatites. The presence of calcite and high Fe and low Ti clinopyroxene point to CO2-saturated conditions. During cooling, fluorbritholite-Ce formed as individual grains or by a fluid-enhanced apatite-britholite transformation. The formation of Fe-rich amphibole, often at the expense of Fe-rich clinopyroxene, reveals a decreasing influence of CO2 and temperature. Presumably, the transformation of orthoclase into microcline occurred simultaneously. Perthitic microcline as a second K-feldspar generation indicates slow cooling from high temperatures. A late stage of CO2-rich hydrothermal-metasomatic processes is suggested by the growth of secondary cancrinite, Sr-Mn carbonates and ancylite-Ce. The composition of primary and early crystallized calcite and apatite makes their origin as residues of an early segregated or independently formed mantle-derived carbonatitic melt more likely than crystallization from a CO2-rich syenitic melt. An origin from melted crustal carbonates is unlikely as well. Therefore, the presence of a carbonatitic melt at an early magmatic evolutive stage, as opposed to a non-carbonatitic melt at a late stage, seems possible for the SJGS rocks.

Effects of irrigation activation techniques on root canal walls after post-space preparation: A scanning electron microscopy study

Effects of irrigation activation techniques on root canal walls after post-space preparation: A scanning electron microscopy study

In-situ observation of defects evolution of graphene nanoflakes in Pt/C catalyst for boosting ORR performance

The structural stability of supported metal nanoparticles determines the activity and longevity of heterogeneous catalysts. Unfortunately, the chemical/thermal working environment inevitably accelerates metal sintering to larger crystallites that leads to the degradation of catalytic performance. Here, we demonstrate that the distribution of defects in carbon support as an inherent parameter plays a crucial role in catalyst sintering. Based on in-situ transmission electron microscopy studies, the strong metal-support interaction between platinum (Pt) nanoparticles and defect-rich graphene nanoflakes largely suppresses metal sintering up to 700 °C. Particularly, the optimal carbon support can be achieved in the annealing process, in which the mass transfer and charge transport can be enhanced by accurately manipulating the distribution of defects in carbon matrix and graphitization degree. It is worth noting that the screened Pt/GNs-300 exhibits impressive oxygen reduction reaction performance with high half-wave potential (0.91 V), mass activity (108.1 A g–1Pt) and excellent stability. By its ascendancy in ORR, the Pt/GNs-300 exhibits a high open-circuit voltage of 1.41 V and a maximum power density of 198.6 mW cm−2 in Zn-air battery, implying its brilliant practicability. This work paves a pathway for achieving sinter-resistant metal-loaded catalysts in energy electrocatalysis.