High-resolution Field-emission Scanning Electron Microscopy Research Articles

Synergistic effects of thermally reduced graphene oxide/zinc oxide composite material on microbial infection for wound healing applications

Infections originating from pathogenic microorganisms can significantly impede the natural wound-healing process. To address this obstacle, innovative bio-active nanomaterials have been developed to enhance antibacterial capabilities. This study focuses on the preparation of nanocomposites from thermally reduced graphene oxide and zinc oxide (TRGO/ZnO). The hydrothermal method was employed to synthesize these nanocomposites, and their physicochemical properties were comprehensively characterized using X-ray diffraction analysis (XRD), High-resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared (FT-IR), Raman spectroscopy, UV-vis, and field-emission scanning electron microscopy (FE-SEM) techniques. Subsequently, the potential of TRGO/ZnO nanocomposites as bio-active materials against wound infection-causing bacteria, including Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, was evaluated. Furthermore, the investigated samples show disrupted bacterial biofilm formation. A reactive oxygen species (ROS) assay was conducted to investigate the mechanism of nanocomposite inhibition against bacteria and for further in-vivo determination of antimicrobial activity. The MTT assay was performed to ensure the safety and biocompatibility of nanocomposite. The results suggest that TRGO/ZnO nanocomposites have the potential to serve as effective bio-active nanomaterials for combating pathogenic microorganisms present in wounds.

Sol–gel synthesized lithium–cobalt co-doped titanium (IV) oxide nanocomposite as an efficient photocatalyst for environmental remediation

Abstract In this study, lithium cobalt co-doped titanium oxide (Li:Co-TiO2) was reported via the sol–gel method in a one-pot synthesis approach and their potential applications were evaluated for the photodegradation of organic dye as photocatalysts. The structural and optical properties of the photocatalysts were respectively elucidated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance spectroscopy (DRS). The morphological and elemental composition of the Li:Co-TiO2 was established by high-resolution field-emission scanning electron microscopy (FESEM) coupled with EDX, which confirmed a successful preparation of the photocatalysts. The modification of TiO2 with Li:Co changes the optical properties of the pristine TiO2 with a reduction in the bandgap (3.26–2.8 eV) of the resultant photocatalysts. The photocatalytic activity of Li:Co-TiO2 composites was examined for their efficacy through the degradation of Methylene Blue (MB) dye. The photodegradation revealed an improved performance of Li:Co-TiO2 in the degradation of MB compared to pristine TiO2. The total amount of the degraded MB dye within the total time interval of the irradiation was recorded to be 72 % and 87 % for TiO2 and Li:Co co-doped TiO2 respectively. The enhanced results obtained from the photocatalytic activity of Li:Co-TiO2 to degrade MB, suggest that the composite is a potential candidate for environmental remediation and photocatalysis applications.

Growth of micro-flowers behind hydrophobic polymer surface and impact of silver and tungsten oxide on the wetting characteristics

In this work, a simple and one-step process was demonstrated to develop hydrophobic polymer surfaces. Commercially available polycarbonate (PC) was treated to turn the front surface hydrophobic with an average wetting contact angle (WCA) as high as 110.5°. The formation of micro-flowers with a coverage density of 9.29 × 106/cm2 on the top of fine base nanostructures was confirmed by a high-resolution field emission scanning electron microscope (FESEM). Impact of typical metal and metal oxide such as silver (Ag) and tungsten oxide (WO3) deposited on such hydrophobic surfaces was demonstrated. Petals of micro-flowers and fine base nanostructures were well decorated with functional metals such as Ag and thus the front surface remained hydrophobic with an average WCA as high as 106.6°. Abundant sharp spikes on the top of narrow hills and dips as revealed in the high-resolution FESEM investigation, were speculated to be the reason behind this hydrophobic characteristic. On the other hand, the hydrophobic surface (WCA of ∼ 110.5°) turned hydrophilic (WCA of ∼11.7°) when the surface was decorated with functional metal oxides, such as WO3. Sessile drop tests were carried out to record average WCA and to understand the wetting characteristics of the specimens. A plausible mechanism for such hydrophobic characteristics as well as the transition from a hydrophobic state to a hydrophilic state has been elucidated.

Growth of ZnO thin Films from Depleted Batteries for Water Remediation

AbstractZnO films were obtained by electrodeposition technique from commercial Zn2+ solutions and those obtained from spent alkaline batteries. The type of counterion and pH impact directly on the structural, morphological, and optical properties of the electrodeposited ZnO films. The morphological and crystallographic orientation differences observed by X‐ray diffraction (XRD) analysis and high‐resolution field emission scanning electron microscopy (HR‐FESEM), demonstrates the influence of the type and origin of precursors used in the ZnO synthesis process. Those samples grown from commercial nitrate solutions exhibit nanocolumns revealing a preferential growth in the (002) direction. On the other hand, random growth (hexagonal plates, agglomerations, clusters, etc.) is observed in samples obtained through recycled solutions. All deposited samples achieved a transparency close to 80 % and an optical band gap of around 3.30 eV. The as‐deposited films were evaluated toward the photodegradation capacity of methylene blue (MB) for potential technological applications. Results exhibit that samples prepared from recycled ZnCl2 solutions presented more than 80 % degradation per mass of ZnO. This work demonstrates a virtuous circle since ZnO films are deposited by a facile and scalable technique from discarded batteries and used for MB photodegradation. Furthermore, the simplicity of recovery of these substrates after application makes them an attractive and pragmatic option for a range of water treatment applications. Synopsis: Zinc from depleted alkaline batteries is reused to obtain ZnO thin films that remove contaminating dyes from water.

Gelatin-Coated TiO2/Pd Hybrid: A Potentially Useful Nanomaterial to Enhance Antibacterial and Anticancer Properties.

Hybrid nanomaterials have attracted considerable interest in biomedicine because of their fascinating characteristics and wide range of applications in targeted drug delivery, antibacterial activity, and cancer treatment. This study developed a gelatin-coated Titanium oxide/palladium (TiO2/Pd) hybrid nanomaterial to enhance the antibacterial and anticancer capabilities. Morphological and structural analyses were conducted to characterize the synthesized hybrid nanomaterial. The surface texture of the hybrid nanomaterials was examined by high-resolution transmission electron microscopy (HR-TEM) and field-emission scanning electron microscopy (FE-SEM). The FE-SEM image revealed the bulk of the spherically shaped particles and the aggregated tiny granules. Energy dispersive X-ray spectroscopy (EDS) revealed Ti, Pd, C, and O. X-ray diffraction (XRD) revealed the gelatin-coated TiO2/Pd to be in the anatase form. Fourier transform infrared spectroscopy examined the interactions among the gelatin-coated TiO2/Pd nanoparticles. The gelatin-coated TiO2/Pd nanomaterials exhibited high antibacterial activity against Escherichia coli (22 mm) and Bacillus subtilis (17 mm) compared to individual nanoparticles, confirming the synergistic effect. More importantly, the gelatin-coated TiO2/Pd hybrid nanomaterial exhibited remarkable cytotoxic effects on A549 lung cancer cells which shows a linear increase with the concentration of the nanomaterial. The hybrid nanomaterials displayed higher toxicity to cancer cells than the nanoparticles alone. Furthermore, the cytotoxic activity against human cancer cells was verified by the generation of reactive oxygen species and nuclear damage. Therefore, gelatin-coated TiO2/Pd nanomaterials have potential uses in treating cancer and bacterial infections.

Characteristics and mechanism of slagging in a 500 t/d MSW incinerator

With the promotion of classified collection of municipal solid waste (MSW), the heating value of waste sent to incinerators has significantly increased, which affects slagging and ash deposition. Thoroughly studying the slag characteristics in incinerators is important for determining its formation conditions and processes. In this study, slag samples from the furnace and superheaters of a 500 t/d incinerator were comprehensively studied. The slag characteristics were measured using X-ray diffraction (XRD), X-ray fluorescence (XRF), and field-emission high-resolution scanning electron microscopy (SEM); the chemical thermodynamic equilibrium calculations were carried out using FactSage; and the melting kinetics were analysed using differential scanning calorimetry (DSC). It was found that under the high-temperature environment of the furnace, CaO and Fe2O3/MgO/Al2O3 react with SiO2 to form low-melting-point eutectic crystals, which are in a molten or semi-molten state and easily adhere to the inner wall of the furnace to form slag that is difficult to remove. CaSO4 does not melt in the furnace but moves with the flue gas and is mainly deposited on the surfaces of the third- and second-stage superheaters. Na2SO4 and K3Na(SO4)2 are in a gaseous state under high-temperature conditions in the furnace, and then transform into a liquid or solid state and condense on the surface of the superheaters. The ash melting process in the furnace can be described using zero-order kinetics. These research results provide a theoretical foundation for the detailed prediction of slagging and ash deposition in waste incinerators.

Synthesis of chitosan-based perylene dye material for photovoltaic solar-cell application

Renewable energy, such as solar energy, is infinite, readily available, and has extensive applications. Dye-sensitized solar cells (DSSCs) have been well developed; thus, they can be developed with low production costs, high efficiency, and facile manufacturing techniques. This study proposes a novel chitosan biopolymer-based perylene dye; the dye is modified by chitosan with perylene-3,4,9,10-tetracarboxylic anhydride using a one-pot acylation of nitrogen nucleophiles for DSSCs. The chitosan biopolymer-based perylene dyes were characterized using attenuated total reflection infrared spectroscopy, solid-state 13C CP-TOSS nuclear magnetic resonance spectroscopy, X-ray powder diffraction analysis, thermogravimetric analysis, X-ray photoelectron spectrometry, and high-resolution field-emission scanning electron microscopy. The ultraviolet-visible and fluorescence spectroscopy of chitosan biopolymer-based perylene dye exhibited a red-shift compared with perylene-3,4,9,10-tetracarboxylic anhydride and chitosan. The DSSC properties of chitosan biopolymer-based perylene dye were investigated, and it exhibited a 2.022 % power-conversion efficiency. Thus, this promising chitosan biopolymer-based perylene dye may have potential applications in solar-cell technology.

Ru thin films prepared by RF magnetron sputtering with Ru targets of different microstructures

Ruthenium (Ru) exhibits excellent electrical properties at the nanoscale, and it can be used to replace Al and Cu as interconnect metals for nodes of 20 nm and below in the next generation of integrated circuits. Ru interconnects mainly exist in the form of films, and Ru targets are used as the key raw materials to produce these films. Establishing whether there is an inheritance relationship in terms of microstructure and electrical properties between these targets and the resultant films will determine whether these are important factors for improving the electrical properties of Ru films and will provide directional guidance for the preparation of Ru targets. In this work, Ru targets were prepared by vacuum hot pressing with two different Ru powders with different morphologies and particle sizes. Ru films were then deposited on SiO2/Si(100) substrates by RF magnetron sputtering at substrate temperatures ranging from room temperature (RT, about 25 °C) to 400 °C. The microstructures and electrical properties of the Ru targets and Ru films were investigated by high-resolution field-emission scanning electron microscopy, x ray diffraction, atomic force microscopy, four-probe resistivity measurements, and digital conductivity tests. The results showed that Ru targets with a more uniform microstructure had lower resistivity; furthermore, Ru films deposited by Ru targets with a more uniform microstructure were preferentially crystallized, and they also had a faster average deposition rate, a smaller average grain size, and lower surface roughness. However, no correlation was found between the crystal orientations of the Ru films and Ru targets.

Optimizing the accessibility of zeolite Y on FCC catalyst to improve heavy oil conversion capacity

Optimizing the accessibility of zeolite Y, the main active component in fluid catalytic cracking (FCC) catalyst, is a crucial strategy to improve the heavy oil cracking performance of FCC catalysts. Four FCC catalysts with different Y zeolite content were prepared via in-situ crystallization method by adjusting the crystallization time. The distribution characteristics of the Y zeolite in in-situ crystallized catalysts have been characterized by scanning electron microscopy (SEM), laser confocal fluorescence microscopy and high-resolution field emission scanning electron microscopy (HR-FESEM). A unique structural feature of the FCC catalysts has been achieved, with the Y zeolite component mainly distributing in the outer layer of microspheres. The results of adsorption rate of macromolecule probes reveal that the appropriate zeolite layer thickness and topology were beneficial to the mass transfer performance and acid accessibility of FCC catalyst. The effective utilization ratios of zeolite in the novel FCC catalysts for heavy oil cracking on advanced catalyst equipment (ACE) is in good correspondence with the mass transfer performance of macromolecules and the accessibility of acid sites. It could be confirmed that the excellent heavy oil conversion performance of a FCC catalyst does not depend on the content of zeolite, but rather on the distribution characteristics are in favor of the accessibility of zeolite components.

Low-temperature hydrothermal synthesis of BiPO4 for Rhodamine B removal

The synthesis and Rhodamine B removal efficiency of monazite monoclinic BiPO4 by hydrothermal route using Bi(NO3)3·5H2O, K2HPO4·3H2O and HNO3 as staring materials were presented in this work. The obtained samples were characterized by X-ray powder diffraction, high-resolution transmission field-emission scanning electron microscopy and diffuse reflectance UV-Vis spectrometry. The results showed that, by selecting suitable reaction parameters, the pure monazite monoclinic phase of BiPO4 was received readily at hydrothermal temperature as low as 130 oC, considerably lower than that reported previously. The obtained monazite monoclinic phase of BiPO4 powders exhibited a high removal efficiency of 96% for 150 min under 365nm-UV irradiation. The mechanism of the Rhodamine B photodegradation reaction over the synthesized monazite monoclinic BiPO4 was also proposed.

Micro‐Raman spectroscopy and complementary techniques applied for the study of copper and iron wastes from Motya (Italy)

AbstractThis work is the first archaeometric investigation on copper and iron wastes from the Phoenician site of Motya (Sicily, Italy), dating back to the 8th to the 4th century BC. The samples were analyzed through micro‐Raman Spectroscopy (μ‐RS), Optical Microscopy (OM), Scanning Electron Microscope‐Energy‐Dispersive X‐ray Spectroscopy (SEM‐EDS), High‐Resolution Field Emission Scanning Electron Microscopy (HR‐FESEM), and Electron Micro‐Probe Analysis (EMPA). Micro‐Raman techinique permitted to identify both primary phases, for example, calchopyrite, and secondary products such as cuprite and copper thrihydroxychlorides in the Cu‐slags and goethite in the Fe‐slags. SEM and HR‐FESEM imaging showed the occurrence of inhomogeneous microstructures in the Cu‐ and Fe‐slags due to elements segregation, solidification, and corrosion. EMPA data revealed that the archaeometallurgical wastes from Motya can be differentiated on the basis of their chemical compositions. These preliminary results showed different typologies of by‐products, such as base metals speiss, copper slags from smelting sulfide ore with matte, and iron smelting and smithing slags, suggesting different stages of copper and iron productions.

Aging study on BiFe0.95Mn0.05O3 ferroelectric thin films with different preferred orientations

The BiFe0.95Mn0.05O3 (BFMO) thin films were epitaxial grown on the SrRuO3/LaAlO3 (SRO/LAO) single crystal substrates with different orientations (<100 >,<110 >and<111 >) by sol-gel and layer-by-layer rapid thermal annealing methods, respectively. The test techniques including X-ray diffraction (XRD), Raman, high resolution field emission scanning electron microscope (HR-SEM) and atomic force microscope (AFM) were applied to analyze the structure of the film samples. The results showed that a two-phase coexistence structure grown in all three films with the rhombohedral R3c as the main phase and the orthogonal Pnma as the second phase. The PFM tests revealed that the <111> oriented sample had normal island domain configuration, while the <100> and <110> oriented samples mainly grew non-180° domains. By comparing the aging behavior of the three samples after a room temperature period of aging for 30 and 120 days, it was believed that the film samples with different orientations appeared distinct aging degrees due to the different number of polarized equivalent components along <111> direction and the different angle between the equivalent components and the applied electric field direction. In particular, the film sample with <111> orientation showed almost no aging. It was also believed that the defect dipole pinning happened in the ferroelectric domain bodies would play a leading role in the aging process.

Structural, Magnetic, and Magnetocaloric Studies of Ball-Milled Fe100−xTx (T = Ni and Mn) Alloy

Iron-transition metal-based binary and ternary alloys have attracted great attention due to their relevant mechanical, electrical, and magnetic properties. In this paper, we systematically investigate the structural, magnetic, and magnetocaloric behavior of as-milled Fe65T35 (T = Ni and Mn) alloy. The polycrystalline alloys were produced by the planetary ball milling, using a powder-to-ball ratio of 1:3. A structural study reveals that both Fe65Ni35 and Fe65Mn35 compounds have stabilized in α and γ mixed phase within the cubic crystal structure. The alloyed compounds are further characterized by high-resolution field emission scanning electron microscopy (HR-FESEM), which confirms the mixing of both metals in the alloying process. Temperature-dependent magnetic studies do not show any blocking in zero-field-cooled and field-cooled results; however, the field-dependent magnetization study demonstrates the ferromagnetic nature with small hysteresis in both compounds. Both compounds show a significant magnetocaloric effect over a wide temperature range around room temperature. Fe65Ni35 exhibit a slightly higher value in comparison to Fe65Mn35. In both the alloys, magnetic entropy change follows the power law behavior against the external magnetic field, and the value of exponent ‘m’ explains the presence of magnetic correlation. Our investigation in this study communicates that the phase control or coexistence of both phases may be efficacious in obtaining the desirable characteristic of magnetic and magnetocaloric demeanors in such a binary Fe-T alloy.

Characteristics of the Upper Cretaceous Yogou transitional formation and source rock potential, Niger rift basin

A High-resolution Field-emission scanning electron microscopy (FE-SEM) technique was used to investigate the complex Upper Cretaceous Yogou transitional Formation and source rock potential. The source rock consists of complex interfingering laminae of claystone, sandstone and shale of marine-transitional environments. Thermal maturity from Rock-Eval pyrolysis placed it between immature to early mature oil windows with Tmax ranging between 419 0C and 440 0C. Organic matters in the studied location are mainly bitumen and kerogen in a ratio of 3:1. Both the organic matters have micro to nano-scale organic pores, indicating a relatively high thermal maturity phase of the organic matter constituents. Several forms of pyrites exist in the Formation; euhedral, detrital, framboids and sunflower pyrite. The framboidal pyrites are large to medium sizes with diameters ranging from 63.1 to 3.27 μm. With increasing depth, the frambiods diameter decreases but increase in abundance. Based on the framboidal pyrite distributions, the lower Yogou source rock has relatively high organic content than the upper Yogou source rock; the high abundance of detrital pyrites at 2590 m depth is evidence of paleo-erosional reworked sediments that may constitute a surface of unconformity or marine to terrestrial transition zone. The pyrites with high abundance at depth 2605 m are all recrystallized, supporting the post formation erosion/exposure to air and/or water. The petrographic investigation also revealed the presence of well-preserved juvenile pollen of several microns in dimensions in the upper Cretaceous source rock formation. Based on these well preserved fossils and the relative abundance of pyrite at the depth of 2585 m, a euxinic to anoxic environment prevailed in the low section of the Yogou Formation, whereas the upper section is dominated by oxic to anoxic environment, where pyrite and organic matters are relatively low. Micro-cracks running parallel to bitumen/host rock boundary are paths for primary oil expulsion and migration. Where these micro cracks are not present may be due to differences in facies and deformation styles between the brittle clasts and the ductile clays present in the Formation. The newly documented juvenile pollens are important discovery that will help in reconstructing the paleo-history of the Niger Rift Basin.

Role of Cr Doping on the Structure, Electronic Structure, and Electrochemical Properties of BiFeO3 Nanoparticles.

BiFe1−xCrxO3, (0 ≤ x ≤ 10) nanoparticles were prepared through the sol–gel technique. The synthesized nanoparticles were characterized using various techniques, viz., X-ray diffraction, high-resolution field emission scanning electron microscopy (HRFESEM), energy dispersive spectroscopy (EDS), UV–Vis absorption spectroscopy, photoluminescence (PL), dc magnetization, near-edge X-ray absorption spectroscopy (NEXAFS) and cyclic voltammetry (CV) measurements, to investigate the structural, morphological, optical, magnetic and electrochemical properties. The structural analysis showed the formation of BiFeO3 with rhombohedral (R3c) as the primary phase and Bi25FeO39 as the secondary phase. The secondary phase percentage was found to reduce with increasing Cr content, along with reductions in crystallite sizes, lattice parameters and enhancement in strain. Nearly spherical shape morphology was observed via HRFESEM with Bi, Fe, Cr and O as the major contributing elements. The bandgap reduced from 1.91 to 1.74 eV with the increase in Cr concentration, and PL spectra revealed emissions in violet, blue and green regions. The investigation of magnetic field (H)-dependent magnetization (M) indicated a significant effect of Cr substitution on the magnetic properties of the nanoparticles. The ferromagnetic character of the samples was found to increase with the increase in the Cr concentration and the increase in the saturation magnetization. The Fe (+3/+4) was dissolved in mixed-valence states, as found through NEXAFS analysis. Electrochemical studies showed that 5%-Cr-doped BFO electrode demonstrated outstanding performance for supercapacitors through a specific capacitance of 421 F g−1 measured with a scan rate of 10 mV s−1. It also demonstrated remarkable cyclic stability through capacitance retention of >78% for 2000 cycles.

Quasi-Solid-State SiO2 Electrolyte Prepared from Raw Fly Ash for Enhanced Solar Energy Conversion.

Quasi-solid-state electrolytes in dye-sensitized solar cells (DSSCs) prevent solvent leakage or evaporation and stability issues that conventional electrolytes cannot; however, there are no known reports that use such an electrolyte based on fly ash SiO2 (FA_SiO2) from raw fly ash (RFA) for solar energy conversion applications. Hence, in this study, quasi-solid-state electrolytes based on FA_SiO2 are prepared from RFA and poly(ethylene glycol) (PEG) for solar energy conversion. The structural, morphological, chemical, and electrochemical properties of the DSSCs using this electrolyte are characterized by X-ray diffraction (XRD), high-resolution field-emission scanning electron microscopy (HR-FESEM), X-ray fluorescence (XRF), diffuse reflectance spectroscopy, electrochemical impedance spectroscopy (EIS), and incident photon-to-electron conversion efficiency (IPCE) measurements. The DSSCs based on the quasi-solid-state electrolyte (SiO2) show a cell efficiency of 5.5%, which is higher than those of nanogel electrolytes (5.0%). The enhancement of the cell efficiency is primarily due to the increase in the open circuit voltage and fill factor caused by the reduced electron recombination and improved electron transfer properties. The findings confirm that the RFA-based quasi-solid-state (SiO2) electrolyte is an alternative to conventional liquid-state electrolytes, making this approach among the most promising strategies for use in low-cost solar energy conversion devices.

Study on the Pore Structure and Fractal Characteristics of Different Lithofacies of Wufeng-Longmaxi Formation Shale in Southern Sichuan Basin, China.

Gas content and flow characteristics are closely related to shale lithofacies, and significant differences exist in the pore structure and fractal characteristics among lithofacies. In this study, X-ray diffractometer (XRD), field-emission scanning electron microscopy (FE-SEM), gas adsorption (N2 and CO2), and fractal theory were employed to systematically characterize the pore attributes of the marine Wufeng–Longmaxi formation shales. The information of various pores and microfractures among lithofacies was extracted and quantified via high-resolution FE-SEM image stitching technology. Shales were classified into four types based on mineral compositions, and siliceous shales possess the largest SEM-based surface porosity (2.84%) and the largest pore volume (PV) (average 0.0243 cm3/g) as well as specific surface area (SSA) (average 28.06 m2/g). The effect of lithofacies variation on the PV of shale is minor. In contrast, the lithofacies variation has a significant impact on the SSA, and the SSA of siliceous shale is 39.11% higher than that of argillaceous shale. PV and SSA show strong positive correlation with the total organic carbon (TOC) content but negative correlation with clay minerals. Siliceous shales have the greatest fractal dimension D1 (pore surface roughness) (average 2.6821), which is contributed by abundant organic matter pores with more complicated boundaries. The largest fractal dimension D2 (pore structure complexity) (average 2.8263) is found in mixed shales, which is attributed to well-developed intraparticle (intraP) pores associated with carbonate mineral dissolution. This indicates that siliceous shales have the highest methane adsorption capacity and that shale gas desorption, diffusion, and seepage are more difficult in mixed shales.

Hybrid composite materials generated via growth of carbon nanotubes in expanded graphite pores using a microwave technique

Herein we demonstrate a facile in-situ synthesis method by selection of expanded graphite as a matrix growth microreactor, nickel nitrate (Ni(NO3)2) as a growth catalyst and naphthalene as a carbon source, assisted by a conventional household microwave oven. Affection parameters related to control of the growth process, such as the microwave heating time, catalyst concentration and carbon source concentration. The optimized experimental conditions that exhibit excellent microstructure were: a carbon source concentration of 20.0 mg/ml, a catalyst concentration of 10.0 mg/ml and a microwave reaction time of 30 s. The microstructure of the synthesized composites was investigated and a solid-gas growth mechanism with this carbon source precursor is proposed. The micro morphology, formed CNT structure and resistivity of the composites are fully characterized and analyzed by thermal field emission high-resolution scanning electron microscopy (FESEM), confocal laser Raman spectrometer (Raman) and a four-point probe resistivity meter. All characterization data show a uniform CNT diameter distribution of approximately 30.0 nm with a low resistivity of the composites (1.12 × 10−5 Ω·m), indicating uniform hybrid composite material formation with novel physical properties.

Polymer-Templated Durable and Hydrophobic Nanostructures for Hydrogen Gas Sensing Applications.

A simple and hands-on one-step process has been implemented to fabricate polymer-templated hydrophobic nanostructures as hydrogen gas sensing platforms. Topographic measurements have confirmed irregular hills and dips of various dimensions that are responsible for creating air bubble pockets that satisfy the Cassie–Baxter state of hydrophobicity. High-resolution field-emission scanning electron microscopy (FESEM) has revealed double-layer structures consisting of fine microscopic flower-like structures of nanoscale petals on the top of base nanostructures. Wetting contact angle (WCA) measurements further revealed the contact angle to be ~142.0° ± 10.0°. Such hydrophobic nanostructures were expected to provide a platform for gas-sensing materials of a higher surface area. From this direction, a very thin layer of palladium, ca. 100 nm of thickness, was sputtered. Thereafter, further topographic and WCA measurements were carried out. FESEM micrographs revealed that microscopic flower-like structures of nanoscale petals remained intact. A sessile drop test reconfirmed a WCA of as high as ~130.0° ± 10.0°. Due to the inherent features of hydrophobic nanostructures, a wider surface area was expected that can be useful for higher target gas adsorption sites. In this context, a customized sensing facility was set up, and H2 gas sensing performance was carried out. The surface nanostructures were found to be very stable and durable over the course of a year and beyond. A polymer-based hydrophobic gas-sensing platform as investigated in this study will play a dual role in hydrophobicity as well as superior gas-sensing characteristics.

Micro‐Raman spectroscopy and complementary techniques for the study of iron weapons from Motya and Lilybaeum (Sicily, Italy): Corrosion patterns in lagoon‐like and calcarenitic hypogea environments

AbstractMicro‐Raman spectroscopy (μ‐RS) has been used to characterize mineralogical phases of corroded iron materials, buried in lagoon‐like and calcarenitic hypogea environments. A set of samples from the Phoenician site of Motya (8th–6th centuries BC, Sicily) and from the Punic Necropolis of Lilybaeum (4th century BC, Sicily) were analyzed combining μ‐RS with scanning electron microscopy‐energy‐dispersive X‐ray spectroscopy (SEM‐EDS) and high‐resolution field emission scanning electron microscopy (HR‐FESEM). Micro‐Raman results revealed the presence of magnetite, goethite, lepidocrocite, and hematite as the main corrosion products and soil minerals as quartz, calcite, barite, actinolite, microcline, zircon, and Ti‐oxides. SEM and HR‐FESEM allowed exploring micro‐ and sub‐micrometer structures of iron oxy‐hydroxides though sections from rim to core. The different corrosion models suggest polymorphic inter‐conversions among iron oxy‐hydroxides and dissolution‐re‐precipitation reactions. In addition, the occurrence of magnetite and metal core that survived in armors buried in the hypogea site of Lilybaeum indicates more stable environmental conditions than those of Motya.