Electron Microscopy Mapping Research Articles

Thin film growth and mechanical properties of CrFeCoNi/TiNbZrTa multilayers

Multilayers of high entropy alloys (HEA) are picking up interest due to the possibility of altering material properties by tuningcrystallinity, thickness, and interfaces of the layers. This study investigates the growth mechanism and mechanical properties of CrFeCoNi/TiNbZrTamultilayers grown by magnetron sputtering. Multilayers of bilayer thickness (Λ) from 5 nm to 50 nm were grown on Si(100) substrates. Images taken by transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping revealed that the layers were well defined with no occurrence of elemental mixing. Multilayers with Λ < 20 nm exhibited an amorphous structure. As Λ increased, the CrFeCoNi layer displayed a higher crystallinity in comparison to the amorphous TiNbZrTa layer. Themechanical properties were influenced by thecrystallinity of the layers and stresses in the film. The film with Λ = 20 nm had the highest hardness of approximately 12.5 GPa owing grain refinement of the CrFeCoNi layer. An increase of Λ ≥ 30 nm resulted in a drop in the hardness due to the increase in crystal domains of the CrFeCoNi layer. Micropillar compression induced shear in the material rather than fracture, along with elemental intermixing in the core of the deformed region of the compressed micropillar.

Preparation of amorphous carbon membranes synthesized via a glucose-solution hydrothermal method

Carbon-based membranes are in the limelight as novel and high-performance materials for various applications. In this study, microporous carbon membranes were synthesized on porous alumina via a hydrothermal method from aqueous glucose solutions. The operating time and temperature for the hydrothermal treatment by evaluating the surface microstructure of the as-prepared membranes using various techniques like scanning electron microscopy (SEM) and electron probe microanalyzer mapping (EPMA). The SEM micrographs and the EPMA results indicate that the membranes formed were also deposited in the interiors of the porous alumina. A carbon membrane with few pinholes was prepared via a hydrothermal treatment at 200 °C for 5 h. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses suggest that the obtained membranes are composed of amorphous carbon, including hydroxy groups. The result of the gas transmission rate (GTR) measurement indicates that the pore size of the amorphous carbon membranes had pores with a diameter of ∼0.3 nm. The ideal gas selectivities for H2/N2, N2/CH4, and H2/SF6 were over Knudsen theoretical values, showing approximately 7.0, 9.5, and 13.5, respectively.

Hollow Carbon Nanorod Confined Single Atom Rh for Direct Formic Acid Electrooxidation.

Nearly theoretical 100% atomic utilization (supposing each atom could serve as independent sites to play a role in catalyz) of single-atom catalysts (SACs) makes it highly promising for various applications. However, for most SACs, single-atom sites are trapped in a solid carbon matrix, which makes the inner parts hardly available for reaction. Herein, a hollow N-doped carbon confined single-atom Rh (Rh-SACs/HNCR) is developed via a coordination-template method. Both aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy mapping confirm the uniform distribution of Rh single atoms. Owning to the unique hollow structure and effective carbon confinement, excessive conversion from pyridinic/pyrrolic N to graphic N is hindered. As a proof of concept, Rh-SACs/HNCR exhibits superior activity, stability, selectivity, and anti-poisoning capability in formic acid oxidation reaction compared with the counterpart Rh/C, Pd/C, and Pt/C catalysts. This work provides a powerful strategy for synthesizing hollow carbon confined single-atom catalysts apply in various energy-related systems.

Van der Waals SWCNT@BN Heterostructures Synthesized from Solution-Processed Chirality-Pure Single-Wall Carbon Nanotubes.

Single-wall carbon nanotubes in boron nitride (SWCNT@BN) are one-dimensional van der Waals heterostructures that exhibit intriguing physical and chemical properties. As with their carbon nanotube counterparts, these heterostructures can form from different combinations of chiralities, providing rich structures but also posing a significant synthetic challenge to controlling their structure. Enabled by advances in nanotube chirality sorting, clean removal of the surfactant used for solution processing, and a simple method to fabricate free-standing submonolayer films of chirality pure SWCNTs as templates for the BN growth, we show it is possible to directly grow BN on chirality enriched SWCNTs from solution processing to form van der Waals heterostructures. We further report factors affecting the heterostructure formation, including an accelerated growth rate in the presence of H2, and significantly improved crystallization of the grown BN, with the BN thickness controlled down to one single BN layer, through the presence of a Cu foil in the reactor. Transmission electron microscopy and electron energy-loss spectroscopic mapping confirm the synthesis of SWCNT@BN from the solution purified nanotubes. The photoluminescence peaks of both (7,5)- and (8,4)-SWCNT@BN heterostructures are found to redshift (by ∼10 nm) relative to the bare SWCNTs. Raman scattering suggests that the grown BN shells pose a confinement effect on the SWCNT core.

High temperature oxidation of SiC-coated Fe-Cr-Al-Mo alloys in muffle and concentrated solar furnaces

The maximal temperature of a solar receiver is limited by its resistance to oxidation, thermal cycling and mechanical stresses as it is a key component of solar power plant with a central tower. Currently used Ni-based alloys cannot heat the air coolant at temperatures beyond 1000 K due to the severe oxidation that may affect the surfaces exposed to air at high temperatures, affecting the solar absorptivity of the receiver. A SiC coating should protect a high temperature metallic alloy from oxidation and improve its solar absorptivity, only if the accommodation between the metallic substrate and the ceramic coating is optimized to prevent the coating from cracking and peeling due to the thermal expansion of the assemblage. To reduce the interfacial stresses, SiC was deposited using High Temperature Chemical Vapor Deposition on a pre-oxidized Fe-Cr-Al-Mo alloy, so that a 2µm-thick alumina layer could work as an accommodation layer. The oxidations performed in muffle and solar furnaces (associated to ex situ characterizations using scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping, X-ray diffraction, and room-temperature normal spectral emissivity measurements) have demonstrated that this multilayer structure could support long-term oxidation and thermal stresses up to1400 K without significant changes regarding the spectral emissivity, but the coating peels if the sample is treated at 1600 K. The multilayer structure can therefore work beyond the current working point of solar receivers, nevertheless the accommodation still has to be improved in case of accidental exposures to higher solar fluxes.

Solid-Phase Extraction (SPE) of Salmon Sperm DNA Using a Polyaniline@Molybdenum(IV) Sulfide@Multiwalled Carbon Nanotubes (MWCNTs) Nanocomposite with Spectrophotometric Detection

A novel high-efficient sorbent composed of polyaniline (PANI), MoS2 nanoparticles, and multiwalled carbon nanotubes (MWCNTS) was synthesized and used for the extraction and preconcentration of salmon sperm DNA for the first time. For the effective adsorption of the DNA chain, which has many interacting functional groups, the ability of the MoS2 in the sandwich-like structure to adsorb analytes was combined with the hydrogen bonding ability of the PANI polymer and the high adsorption capacity of MWCNTs with high surface area. With the awareness of the importance of DNA extraction and preconcentration studies, salmon sperm DNA was selected to be the analyte in this study. After rapid extraction and preconcentration of salmon sperm DNA, inexpensive and easy analysis was performed by spectrophotometry that is available in almost every laboratory. This method has the potential to be routinely used in DNA extraction and determination from various media. The characterization of synthesized PANI@MoS2@ MWCNTs was carried out using Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, field emission scanning electron microscopy, scanning electron microscopy mapping, and energy dispersive X-ray spectroscopy. Spectrophotometry at 260 nm was used to determine the DNA. The optimum extraction conditions of the SPE procedure were pH 6.0, 25 of mg adsorbent, 2 min of vortexing, and 1 mL of 2 M sodium hydroxide as the eluent. Under the optimal conditions, the calibration curve was linear from 33 to 567 µg L−1, the relative standard deviation was 2.2% for 100 μg L−1, and the limit of detection limit was 13 μg L−1. The maximum obtained preconcentration factor was 30 and the sorption capacity of synthesized adsorbent for DNA was 9.16 mg g−1.

Wire arc additive manufacturing (WAAM) of nanotreated aluminum alloy 6061

PurposeAdditive manufacturing (AM) can achieve significant weight savings with only minor compromises in strength if high-performance wrought aluminum alloys are used as feedstock. Despite the advantages in strength that aluminum alloys (AA) 6061 offer, they cannot be manufactured via printing because of hot cracking and other solidification problems. The purpose of this study is to achieve high-quality printing of AA6061 with nanotreated wires.Design/methodology/approachNanotreating was used to modify the AA6061 alloy composition by adding a small fraction of nanoparticles to enhance the alloy’s manufacturability and resultant properties. Wire arc additive manufacturing (WAAM) was used to print the nanotreated AA6061 wire feedstock. The microstructure of the printed AA6061 was characterized by X-ray crystallography, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy mapping. The microhardness profile, tensile behavior and fracture surface were analyzed.FindingsThis work successfully used WAAM to print nanotreated AA 6061 components. The resulting AA6061 parts were crack-free, with exceptional grain morphology and superior mechanical properties. Owing to the excellent size control capabilities of nanoparticles, a homogeneous distribution of small grains was maintained in all deposited layers, even during repeated thermal cycles.Originality/valuePrevious studies have not successfully printed AA6061 using WAAM. Conventional WAAM products exhibit anisotropic mechanical properties. The nanotreated AA6061 was successfully printed to achieve homogeneous microhardness and isotropic tensile properties. The promising results of this study reflect the great potential of nanotech metallurgy as applied to the WAAM process.

Quantitative Analysis of Fuel Cell Cathode Catalyst Layer Degradation Using Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy

Proton exchange membrane fuel cells (PEMFCs) are a central technology for the electrification of the heavy-duty automotive fleet, ultimately enabling reduced carbon emissions. However, improvements in lifetime and cost are necessary before mass adoption of PEMFC vehicles is achieved. Significant research into analyzing and mitigating degradation of catalyst layers (CLs) is ongoing and this work highlights a transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) approach aimed at quantifying electrochemically active surface area (ECSA) loss through the thickness of CLs resulting from electrochemical-applied, catalyst-specific accelerated stress tests or ASTs.Several mechanisms contribute to degradation of the catalysts in PEMFCs, including Ostwald ripening, coalescence, and formation of a Pt band within the membrane, which result in decreased active surface area throughout the CL. TEM has often been used in conjunction with electrochemical testing to infer changes in the catalyst nanoparticle size, distribution, and changes to the support materials within the catalyst layer (CL) to investigate catalyst. Typically, high-magnification TEM with high-resolution are used to infer localized changes within the CL by examining shape and size to provide information concerning the degradation mechanism. Low-magnification TEM is typically used to observe changes in the support, ionomer, and catalyst distribution. Here we use a quantitative approach to show elemental differences within the CL by using scanning transmission electron microscopy and energy dispersive spectroscopy maps (STEM/EDS) for a given MEA that underwent catalyst-specific ASTs. This approach uses the fluorine to platinum ratio (F/Pt) from a fresh sample as a benchmark to track loss of Pt through the thickness of the CL of aged samples. This information can then be used to compare differences in various locations on the MEA in relationship to gas inlets and outlets as well as changes induced by different stressors during the catalyst ASTs. This analysis complements studies using bulk techniques, such as electrochemical ECSA via cyclic voltammetry and micro-X-ray diffraction (µ-XRD), to confirm trends in CL degradation.

An Electrochemically Polymerized Protective Layer for Magnesium Metal Anode

Rechargeable magnesium (Mg) batteries are promising beyond Li-ion technologies due to their high volumetric capacity (3832 mAh cm−3) and high natural abundance. Nonetheless, Mg metal anode is incompatible with most conventional electrolytes which leads to the formation of an ionically passivating layer. Mg also suffers from growth of dendrites similar to Li, which causes failure of the cells. In this study, we electrochemically polymerized 1,3-dioxolane (DOL) to form a thin Mg2+-conducting elastomeric artificial solid electrolyte interphase (ASEI) layer by electrochemically pretreating Mg metal anodes. We found that this protective ASEI layer enables excellent cyclability of Mg-Mg symmetric cells at high current density (0.5 mA cm-2) over 400 hours at a stable low overpotential (0.50 V vs. Mg2+/Mg) without cell short-circuiting, while untreated pristine Mg symmetric cells quickly failed. The formation of this ASEI also significantly lowered the impedance of the cells, which proved its capability of conducting Mg2+ ions. Comprehensive surface chemistry analysis was done by X-ray photoelectron spectroscopy (XPS) which showed that an ASEI mainly consists of poly-DOL was formed, along with various Mg salts which are instrumental to the conductance of Mg2+ ions. More importantly, poly-DOL component in the elastomer was well preserved post-cycling, which contributed to the long-term cyclability and low voltage hysteresis of pretreated Mg-Mg cells, as compared to the pristine ones. Focused ion beam (FIB) – scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) mapping showed that a generally uniform layer was formed on the surface and this ASEI is roughly 200 µm thick and was able to suppress the growth of Mg dendrites after cycling for 400 hours at 0.03 mA cm-2 current density, as compared to the rampant sphere-shaped dendrites on the surface of pristine Mg anodes after cycling. This is the first ever report on the successful formation of poly-DOL ASEI on Mg metal anodes as a protective layer and by electrochemical polymerization method that effectively enhanced the electrochemical cycling performance of the Mg metal anodes. Figure 1

Construction of high-performance ZnO/C/Bi&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; composites and their application in NiZn battery

<p indent="0mm">The zinc anode easily encounters some problems such as dendrite growth, shape change, and hydrogen evolution during the charge-discharge process, which lead to the poor cycle life of NiZn battery. To solve these problems, a novel method for surface modification of ZnO was proposed. By using PVA as carbon source, ZnO/C composite was first synthesized; and then, ZnO/C/NH₄Bi₃F₁₀ composite was prepared in the ethylene glycol; ZnO/C/ NH₄Bi₃F₁₀ finally transformed into ZnO/C/Bi₂O₃ after being calcined at high temperature. X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and elemental distribution mapping results confirmed the successful synthesis of ZnO/C/Bi₂O₃ composites. The formation mechanism of the composites was discussed in detail. Cyclic voltammetry (CV), electrochemical impedance spectrosocopy (EIS) and constant current charge-discharge tests showed that ZnO/C/Bi₂O₃ composite with the Bi₂O₃ content of 2% displayed the highest electrochemical activity. Furthermore, the NiZn battery assembled from the composite with 2 wt% Bi₂O₃ displayed a cycle life up to 1806 times with the highest energy density of 166.5 Wh kg⁻¹. The energy density of 164.44 Wh kg⁻¹ and Coulombic efficiency of 90% were still maintained after 1806 cycles. The as-prepared ZnO/C/Bi₂O₃ composites exhibit excellent electrochemical performance and great potential for practical applications. This innovative synthesis method is hopeful to be extended to prepare other composites.

Magnetocaloric properties of transition metal doped high entropy LaFe11Si2 alloys on Fe sites

The working temperature range of magnetic refrigeration (MR) is severely limited by the narrow range of magnetic entropy change (ΔSM) of magnetocaloric (MC) materials, which especially hinders MR applications near room temperature. Here, high-entropy La(Fe, Si)13 based MC materials with increasing number of equimolar transition metal elements such as Mn, Co, Ni, and Cr occupying Fe sites were synthesized using arc melting and annealing, to stabilize the La(Fe, Si)13 phase, and to increase δFWHM. Atomic resolution aberration corrected scanning transmission electron microscopy and elemental mapping confirmed that the doped transition metal elements uniformly occupy the Fe sites. Due to enhanced configuration entropy, the high entropy alloy has achieved La(Fe, Si)13 single phase structure. Magnetic property measurements reveal that the working temperature range of the high entropy alloy has increased by 141.3%. This work provides a new method to design novel MC materials for better stability and larger temperature range.

Use of cationic p[2-(acryloyloxy)ethyl] trimethylammonium chloride in hydrogel synthesis and adsorption of methyl orange with jeffamine based crosslinker

In this study, a noncommercial polyetheric-structured jeffamine-based crosslinker was used by being synthesized in the synthesis of a hydrogel of a cationic-structured p[2-(acryloyloxy)ethyl] trimethylammonium chloride p(AETAC). The hydrogels containing crosslinkers with five various percentages (0.1, 0.25, 0.75, 1) were synthesized and were aimed to be used as an adsorption material. For the applications, a 1% crosslinked hydrogel (GEL 5) was utilized for the adsorption of a mono-azo chemically structured anionic characterized methyl orange (C14H14N3NaO3S) (MO) colorant. The structure of the jeffamine-based crosslinker was inspired by FT-IR, 1H-NMR, 13C-NMR, and LC-MS analysis, while the hydrogel structure characterization was elucidated by FT-IR spectroscopy. The morphological structure of the hydrogel was examined using scanning electron microscopy (SEM), SEM-EDX, and elemental mapping methods. Concurrently, the mechanical resistance of GEL 5 was tested, and its swelling behavior was examined in different media and pH values. GEL 5, considered decent adsorbent material owing to its structural qualifications, was used in the toxic MO dye adsorption process. In adsorption studies, the maximum qe value of the GEL 5 hydrogel was 547.34 ± 40.00 mg/g in 1000 mg/L MO dye solution. Furthermore, desorption studies have shown that it has reusability, which is a crucial factor in adsorbent selection.

BIOSIGNATURE PRESERVATION AIDED BY ORGANIC-CATION INTERACTIONS IN PROTEROZOIC TIDAL ENVIRONMENTS

Abstract The preservation of organic biosignatures during the Proterozoic Eon required specific taphonomic windows that could entomb organic matter to preserve amorphous kerogen and even microbial body fossils before they could be extensively degraded. Some of the best examples of such preservation are found in early diagenetic chert that formed in peritidal environments. This chert contains discrete domains of amorphous kerogen and sometimes kerogenous microbial mat structures and microbial body fossils. Our understanding of how these exquisite microfossils were preserved and the balance between organic degradation and mineral formation has remained incomplete. Here, we present new insights into organic preservation in Proterozoic peritidal environments facilitated through interactions among organic matter, cations, and silica. Organic matter from Proterozoic peritidal environments is not preserved by micro- or cryptocrystalline quartz alone. Rather, preservation includes cation-rich nanoscopic phases containing magnesium, calcium, silica, and aluminum that pre-date chert emplacement and may provide nucleation sites for silica deposition and enable further chert development. Using scanning electron microscopy and elemental mapping with energy dispersive X-ray spectroscopy, we identify cation enrichment in Proterozoic organic matter and cation-rich nanoscopic phases that pre-date chert. We pair these analyses with precipitation experiments to investigate the role of cations in the precipitation of silica from seawater. Our findings suggest that organic preservation in peritidal environments required rapid formation of nanoscopic mineral phases through the interactions of organic matter with seawater. These organic-cation interactions likely laid the initial foundation for the preservation and entombment of biosignatures, paving the way for the development of the fossiliferous chert that now contains these biosignatures and preserves a record of Proterozoic life.

Synthesis and electrorheological properties of TiOF2 @SiO2 cubic-like core/shell nanocomposite

In this work, TiOF2@SiO2 cubic-like core/shell nanoparticles was prepared using a simple two-step method. The cubic-like Ti-containing precursor is initially prepared via a template-free solvethermal method to provide a huge surface for the coating uniformly with the SiO2 by a next hydrolysis. Through Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and element mapping, the surface morphology and structure was exhibited. The X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS) can test the component, elements, as well as functional groups. And the ER effect at diverse electric field strengths is tested by a HAKKE rotating rheometer. According to the result, it can be concluded that the coating of SiO2 can decrease the leaking electric current density and increase the shear stress, which makes the special cubic-like TiOF2@SiO2 core/shell nanoparticles become a promising ER material.

Enhanced removal of oxytetracycline from wastewater using bimetallic Fe/Ni nanoparticles combined with ZIF-8 nanocomposites.

The integration of metal-organic frameworks with other functional materials has recently emerged as a promising approach for creating innovative materials for environmental remediation. Here, a nano-sized iron/nickel (Fe/Ni) functionalized zeolitic imidazolate framework-8 (ZIF-8-Fe/Ni) was fabricated for oxytetracycline (OTC) removal from wastewater. Cyclic voltammetry and amperometric I-t measurements indicated that OTC was degraded by ZIF-8-Fe/Ni. X-ray diffraction spectroscopy (XRD), transmission electron microscopy mapping (TEM-mapping) and X-ray photoelectron spectroscopy (XPS) indicated that Fe/Ni was evenly dispersed throughout ZIF-8 and partially oxidized after reaction with OTC. OTC adsorption isotherms and kinetics best fitted the Langmuir isotherm (R2>0.982) and pseudo-second-order model (R2>0.997), respectively. Reduction kinetics data followed the pseudo-first-order model (R2>0.905), where the apparent activation energy (Ea) was 22.9kJmol-1, demonstrating that OTC degradation was mainly via a chemical process. The practical removal efficiency of OTC from real wastewater by ZIF-8-Fe/Ni was 92.6%, where even after application of ZIF-8-Fe/Ni for 5 consecutive removal cycles, a high OTC removal of 74.9% was maintained. Thus ZIF-8-Fe/Ni exhibited both high removal efficiency and good recyclability.

Gas sensors based on Pd-decorated and Sb-doped SnO2 for hydrogen detection

Pd-modified Sb-doped SnO2 nanomaterials were prepared by a simple hydrothermal reaction and reduction method. The as-obtained samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray phosphorescence, and elemental mapping analysis. The extracted results demonstrated even doping of Sb within the SnO2 lattice, and Pd was successfully incorporated on the surface of samples. Compared with the pristine SnO2, 3 mol% Sb doping with 7 wt% Pd decorating exhibited the highest response of 9.7 to 100 ppm H2 at 320 °C and revealed excellent selectivity and cycling stability to hydrogen. The mechanism of the enhanced sensing performance of Pd@Sb-SnO2 can be attributed to the change in the energy band structure by Sb doping, the energy-band bending, and depletion layer generated with the Pd loading. The increased oxygen vacancy caused by the lattice distortion generated by the Sb doping, and the strong metal-support interaction effect between the Pd and SnO2 also plays an important role.

Fabrication and characterization of graphene oxide and glass fiber‐based hybrid epoxy composites

AbstractThis work aims to develop and characterize graphene oxide (GO) and glass fiber (GF)‐based hybrid epoxy composites. Graphite oxide was synthesized by improved Hummers' method, and it was uniformly dispersed in ethanol by ultra‐sonication to form GO suspension. Later, GO and GF‐based hybrid epoxy composites were prepared by hand layup method followed by curing under compression to develop composite sheets accordingly to the ASTM standards (D3039 &amp; D6110‐18). Fourier transform infrared spectra of the neat and the GF‐based hybrid epoxy composites confirmed the formation of improved interface between GO/epoxy and silane coating present on GF surface, which is well validated with the given reaction schematic. Scanning electron microscope and elemental mapping results corroborate our point that the GO filled the voids and empty spaces and lessened the water absorption properties of the composite which is much needed for the application of composites at high altitudes and marine environment. Effect of GO content on mechanical properties of prepared composites was studied by varying the GO content from 0.1 to 1.2 wt%. Mechanical characterization of GO and GF‐based hybrid epoxy composites were carried out by tensile and impact testing. Ultimate tensile strength, impact strength and elongation were increased by ~20%, ~41%, and ~19%, respectively, at 0.4 wt% addition of composition. The avg. delamination factor for this composition (0.4 wt% of GO) reduced as compared to neat epoxy and other wt% compositions for 6‐, 5‐, 4‐, &amp; 3‐mm drill bit sizes.

An Efficient Zr-ZSM-5-st Solid Acid Catalyst for the Polyol Esterification Reaction

In this study, Zr active species were implanted into a ZSM-5 zeolite framework to form a solid acid catalyst through steam treatment and the liquid-solid isomorphous substitution process. The as-synthesized Zr-ZSM-5-st catalyst ensured excellent esterification of trimethylolpropane and fatty acids (FAs) to achieve a polyol ester production yield of 94.41%. Combined with N2 physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, transmission electron microscopy mapping, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption, and inductively coupled mass plasma spectroscopy were conducted. The results revealed that the excellent performance of Zr-ZSM-5-st catalyst could be attributed to the enhanced acidity and the developed surface area and pore structure.

The Effect of 1T Phase Molybdenum Disulfide on the Tribological Performance of Polyethylene Glycol

In our research described in this paper 1T Phase Molybdenum Disulfide/Polyethylene Glycol (200) (1T-MoS2/PEG) was studied as a lubricant for steel-steel contact with the goal of minimizing or eliminating galling. The morphology and structures of 1T-MoS2 were analyzed by various techniques, such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, the friction performance of oleic acid (OA) modified 1T-MoS2 as a lubricants additive for PEG was investigated. The results of the friction test indicated that the average friction coefficient and wear scar diameter of PEG containing 0.1875 wt% 1T-MoS2 were 14.30% and 46.90% less than those of pure PEG, respectively. However, those of 0.1875 wt% 1T-MoS2/PEG modified by OA as lubrication additives were 47.83% and 56.79% lower than those of pure PEG. 1T-MoS2 nanoparticles can not only fill the inherent grooves on the surface of the steel ball, but also form a friction lowering film on the friction interface, thus reducing friction and wear, which was seen from the results of scanning electron microscopy (SEM) and element mapping of the wear scar. This study, most importantly, provides a foundation for the use of 1T-MoS2/PEG and OA/1T-MoS2/PEG as effective lubricants to reduce the friction problems in the mechanical industry.

Quantitative, in situ visualization of intracellular insulin vesicles in pancreatic beta cells

Characterizing relationships between Zn2+, insulin, and insulin vesicles is of vital importance to the study of pancreatic beta cells. However, the precise content of Zn2+ and the specific location of insulin inside insulin vesicles are not clear, which hinders a thorough understanding of the insulin secretion process and diseases caused by blood sugar dysregulation. Here, we demonstrated the colocalization of Zn2+ and insulin in both single extracellular insulin vesicles and pancreatic beta cells by using an X-ray scanning coherent diffraction imaging (ptychography) technique. We also analyzed the elemental Zn2+ and Ca2+ contents of insulin vesicles using electron microscopy and energy dispersive spectroscopy (EDS) mapping. We found that the presence of Zn2+ is an important characteristic that can be used to distinguish insulin vesicles from other types of vesicles in pancreatic beta cells and that the content of Zn2+ is proportional to the size of insulin vesicles. By using dual-energy contrast X-ray microscopy and scanning transmission X-ray microscopy (STXM) image stacks, we observed that insulin accumulates in the off-center position of extracellular insulin vesicles. Furthermore, the spatial distribution of insulin vesicles and their colocalization with other organelles inside pancreatic beta cells were demonstrated using three-dimensional (3D) imaging by combining X-ray ptychography and an equally sloped tomography (EST) algorithm. This study describes a powerful method to univocally describe the location and quantitative analysis of intracellular insulin, which will be of great significance to the study of diabetes and other blood sugar diseases.