Μm Average Diameter Research Articles

Fossil Geyserite and Testate Amoebae in Geothermal Spring Vent Pools: Paleoecology and Variable Preservation Quality in Jurassic Sinter of Patagonia (Deseado Massif, Argentina).

Geyserite is a type of terrestrial siliceous hot spring deposit (sinter) formed subaerially in proximal vent areas, with near-neutral pH, alkali chloride discharge fluids characterized by initial high temperatures (~73°C to up to 100°C) that fluctuate rapidly in relation to dynamic hydrology, seasonality, wind, and other environmental parameters. We analyzed sinters at the Claudia paleogeothermal field from the Late Jurassic (~150 Ma) Deseado Massif geological province, Argentinean Patagonia. The geyserite samples-with spicular to columnar to nodular morphologies-contain abundant microfossils in monotypic assemblages that occur in three diagenetic states of preservation. The best-preserved microfossils consist of vesicle-like structures with radial heteropolar symmetry (~35 μm average diameter), circular apertures, smooth walls lacking ornamentation, and disk- or beret-like shapes. Comparisons with extant, morphologically similar organisms suggest an affinity with the testate amoebae of the Arcella hemisphaerica-Arcella rotundata complex and Centropyxis aculeata strain discoides. These species occur in active geothermal pools between 22°C and 45°C, inconsistent with the temperature of formation of modern geyserites. We propose that the testate amoebae may have colonized the geyserite during cooler phases in between spring-vent eruptive cycles to prey on biofilms. Silica precipitation through intermittent bathing and splashing of fluctuating thermal fluid discharge could have led to their entrapment and fossilization. Petrographic analysis supports cyclicity in paleovent water eruptions and later diagenesis that transformed the opal into quartz. Spatially patchy degradation and modification of the silicified microorganisms resulted in variable preservation quality of the microfossils. This contribution illustrates the importance of microscale analysis to locate early silicification and identify high-quality preservation of fossil remains in siliceous hot spring deposits, which are important in early life studies on Earth and potentially Mars.

Formulation and characterization of Liposomal glutathione as a key component in mitigation of Kwashiorkor disease in children with malnutrition

Background. Kwashiorkor disease is due to deficiency of protein in malnutrition condition. Malnutrition is one of the major drawbacks among the Indian children. In India, the impact of undernutrition among impoverished children is disproportionately felt in rural areas. Due to the unequal distribution of food within the household and the consumption of foods with low nutritional qualities, increases the percent of malnutrition in children. Objective. To formulate liposomal glutathione as a potent high antioxidant agent for delivery nutritional effect in nutraceutical formulations and other food supplements for boosting immunity through combating Kwashiorkor disease during malnutrition condition in children. Method. Nanoliposome of glutathione was formulated by ethanol injection method via formation of organic and aqueous phases. Further, morphology of the formulated liposomal glutathione was characterized using cryo-TEM and confirmed for suitability in nutraceuticals as immune enhancers in children. Result. Glutathione was successfully entrapped in lipid as nanoformulations. Cyro-TEM analysis resulted the shape of the particles are spherical with 0.1 µM average diameter. Conclusion. The overall result concluded that liposomal glutathione is very effective in formulation of nutraceutical as well as food supplements as potent immune booster for children and reduce protein deficiency in malnutrition to cure Kwashiorkor disease.

Dependence on relative humidity in the formation of reactive oxygen species in water droplets

Water microdroplets (7 to 11 µm average diameter, depending on flow rate) are sprayed in a closed chamber at ambient temperature, whose relative humidity (RH) is controlled. The resulting concentration of ROS (reactive oxygen species) formed in the microdroplets, measured by the amount of hydrogen peroxide (H2O2), is determined by nuclear magnetic resonance (NMR) and by spectrofluorimetric assays after the droplets are collected. The results are found to agree closely with one another. In addition, hydrated hydroxyl radical cations (•OH-H3O+) are recorded from the droplets using mass spectrometry and superoxide radical anions (•O2-) and hydroxyl radicals (•OH) by electron paramagnetic resonance spectroscopy. As the RH varies from 15 to 95%, the concentration of H2O2 shows a marked rise by a factor of about 3.5 in going from 15 to 50%, then levels off. By replacing the H2O of the sprayed water with deuterium oxide (D2O) but keeping the gas surrounding droplets with H2O, mass spectrometric analysis of the hydrated hydroxyl radical cations demonstrates that the water in the air plays a dominant role in producing H2O2 and other ROS, which accounts for the variation with RH. As RH increases, the droplet evaporation rate decreases. These two facts help us understand why viruses in droplets both survive better at low RH values, as found in indoor air in the wintertime, and are disinfected more effectively at higher RH values, as found in indoor air in the summertime, thus explaining the recognized seasonality of airborne viral infections.

The gametogenic cycle of an invasive semelparous heterobranch sea slug from northern Patagonia, Argentina, reveals an annual lifespan

This study provides information about the reproductive cycle of the invasive side-gilled sea slug Pleurobranchaea maculata, currently widely distributed along the Argentine coast. The histological analysis of this simultaneous hermaphrodite showed characteristics of a semelparous species with an annual life cycle. The highest spermatogenic and oogenic activity was observed from August to January. Partial evacuations of mature oocytes, measuring over 100 μm in average diameter, occurred continuously during the long spawning season. Oviposition events started in winter and increased in frequency with increasing photoperiod (hours of light) until summer solstices. During February and March, post-reproductive and immature individuals coexisted, while mature individuals were rarely observed. These results represent important information on the reproductive patterns of an invasive species of worldwide ecological and sanitary concern.

Oxidation of fine aluminum particles: thermally induced transformations in particle shells and kinetics of oxide nucleation.

This paper investigates the process of oxidation of fine aluminum powder, consisting of spherical Al particles of 'metal core/oxide shell' type, when heated in air at temperatures below 550 °C. The highly dispersed aluminum powder 'Alex' used in this work (particle size: 0.05-1.5 μm and number average particle diameter (DN): 0.11 μm) was produced by electric explosion of a thin Al wire in argon with subsequent passivation in an oxygen-containing atmosphere. For the first time, the influence of the particle size on the oxidation process has been identified. During the reaction, individual γ-Al2O3 oxide nuclei grow at the surface of Al particles with diameters less than 300 nm without laterally overlapping to form a protective passivating layer, as typically occurs during the oxidation of micron-sized particles or bulk metal. The localization of γ-Al2O3 nuclei is determined by the regions where peeling of the primary amorphous oxide film from the surface of the metal core of an Al particle occurs due to the thermal decomposition of aluminum hydroxides (T ≈ 350 °C) present within the particle shells. A significant increase in the contributions of the following factors leads to a high oxidation rate: the diffusion within the disordered structure of a particle core and the surface diffusion of cations (Ea = 80.6 ± 5.3 kJ mol-1, 400-450 °C), the surface and grain boundary diffusion of oxygen during the growth of γ-Al2O3 crystallites (Ea = 108.3 ± 11.2 kJ mol-1, 470-500 °C) and the surface and grain boundary transport of anions through an amorphous and underlying nanocrystalline oxide layer with a constant thickness (Ea = 205.1 ± 8.6 kJ mol-1, 520-550 °C). The results obtained make it possible to expand the theoretical understanding of the manifestations of the size effect in solid-phase reactions and take into account its influence in practice.

Supercritical fluid and cocrystallization technologies for designing antimicrobial food packaging PLA nanocomposite foams loaded with eugenol cocrystals with prolonged release

Searching for effective strategies to modify the release rate of essential oil derivatives is one of the main challenges in designing prolonged-release antimicrobial food packaging materials. Herein, supercritical fluid technology and cocrystallization engineering were used to develop novel eugenol (EU) prolonged-release poly (lactic acid) (PLA) nanocomposite foams. Eugenol-phenazine (EU-PHE) cocrystals, produced by a solvent-free mechanochemical method, were incorporated by supercritical solvent impregnation (SSI) inside PLA nanocomposite foams with different contents of Cloisite30B® (C30B). The effect of the cocrystallization process and C30B content on the EU release kinetics and its relation with their antimicrobial activity by direct contact (anti-attachment) and release in broth culture were studied. The deposition of isolated spherical-shaped micrometric EU-PHE cocrystal particles with 0.8 µm average diameter inside the pores of PLA foams was evidenced by XRD, SEM, DSC, and TGA analyses. The release mechanism of EU and its cocrystal was defined as a quasi-Fickian diffusion process successfully described by the Korsmeyer-Peppas model with release rate constants up to 3.6-fold lower than the release rate constant of pure EU. The impregnated foam samples completely inhibited the attachment of Listeria monocytogenes and Salmonella Enteritidis and provided prolonged antimicrobial activity in broth culture against both food-borne pathogens. This study suggests a new, environmentally friendly method for designing prolonged-release antimicrobial food packaging materials.

Effect of Process Parameters on the Solid Particle Erosion Resistance of Transparent Materials

The solid particle erosion (SPE) performance of three different transparent materials, polycarbonate solid sheet, plexiglass (Polymethylmethacrylate (PMMA), and laminated glass was investigated. Erosion tests were performed under different impact angles (20°, 30°, 45°, 60°, and 90°) and impinging velocities (75, 150, and 200 m/s). As erodent particles, alumina (Al2O3) with 52 µm average diameter and silicon carbide (SiC), particles with two different dimensions (71, and 348 µm in diameters) were used. The results showed that polycarbonate specimens outperformed the other tested samples regardless of impact velocity and impinging angle conditions. When the erosion resistance of samples at 90° and 75 m/s is taken into consideration, the polycarbonate sheet was found to be at least 14 times more erosion resistant compared to plexiglass, and 23 times more resistant than the laminated glass materials. In addition, polycarbonate exhibited an incubation behavior at lower impact velocity, and with SiC erodent.

Porous NiCo-LDH microspheres obtained by freeze-drying for efficient dye and Cr(VI) adsorption

Hierarchical NiCo-LDH microspheres (NiCo-LDHM) were synthesized via a simple one-step hydrothermal process in the presence of 2-methylimidazole, and a freeze-drying technique was subsequently used to further adjust its microstructure. The obtained porous hierarchical microspheres are about 5 µm in average diameter, and consist of ultrathin nanosheets with an average thickness of 5 nm. The freeze-drying endows LDH microspheres with higher surface area and improved pore structure. The unique hierarchical porous structure, high specific surface area and positive surface charge together contribute NiCo-LDHM’ excellent capability for anionic dyes and heavy metal ions removal, its theoretical adsorption capacities for Congo red (CR), acid fuchsin (AF) and Cr(VI) are 2120, 1176 and 123 mg/g at room temperature respectively. The adsorption of pollutant molecules/ions onto NiCo-LDH microspheres conforms to the quasi-secondary kinetics model. Isotherm studies suggest that the CR adsorption onto adsorbent fits Langmiur model, while AF/Cr(VI) adsorption fits Freundlich model, indicating that the size and morphology of pollutant molecules influence the adsorption process. The adsorption is a spontaneous endothermic process and NiCo-LDHM demonstrates good recyclability, the removal rates of CR, AF and Cr(VI) can still reach 90.7%, 84.7% and 82% after five cycles, respectively. In addition, NiCo-LDH hierarchical microspheres also exhibit good anionic selective adsorption capacity in mixed-dye systems, displaying great potential for water restoration and dye recycling.

The fabrication and characterization of a novel antibacterial curcumin and TiO2 loaded gelatin/silk fibroin: polycaprolactone scaffolds for skin tissue engineering

Skin injuries are common problems and large skin defects or infected skin needs extra attention that make the researchers find new solutions. Herein, a novel biocompatible, biodegradable antibacterial scaffold containing gelatin, TiO2, polycaprolactone, and silk fibroin loaded with different ratios of curcumin (0.5, 1, and 1.5% wt.) was fabricated with electrospinning technique and was tested with various in vitro tests. The cellular investigations (cell adhesion, cell viability, and in vitro migration test) and antibacterial assay revealed the higher efficiency of the scaffold with 1% wt. curcumin and further investigation were performed on this scaffold. The morphological observation confirmed the nanofibrous structure of the scaffold, with 0.10 ± 0.015 μm average fiber diameter. This scaffold showed hydrophilic nature with high swelling ratio absorption and 76.45 ± 5.19% degradation ratio after 2 weeks. Also, it could provide adequate mechanical properties for skin regeneration. The drug-releasing investigation revealed Cur’s controlled release over 48 h. Therefore, this biocompatible and antibacterial scaffold showed high potential for treating skin injuries and is suggested for future in vivo studies.

Polytetrafluorethylene microplastic particles mediated oxidative stress, inflammation, and intracellular signaling pathway alteration in human derived cell lines

Microplastics (MPs) are now widely distributed across the aerial, terrestrial, and aquatic environments. Thus, exposure to MPs via the oral, inhalation, or dermal routes is inevitable. Polytetrafluoroethylene (PTFE)-MPs is mainly used for manufacturing nonstick cookware, semiconductors, and medical devices; however, their toxicity has been rarely studied. In the present study, six different human cell lines, which are representative of tissues and cells that directly or indirectly come into contact with MPs, were exposed to two different sizes of irregular shape PTFE-MPs (with an average diameter of 6.0 or 31.7 μm). PTFE-MPs-mediated cytotoxicity, oxidative stress, and changes in proinflammatory cytokine production were then evaluated. We found that the PTFE-MPs did not induce cytotoxicity under any of the experimental conditions. However, PTFE-MPs (especially average diameter of 6.0 μm) induced nitric oxide and reactive oxygen species production in all the cell lines tested. Moreover, both sizes of PTFE-MPs increased the secretion of tumor necrosis factor alpha and interleukin-6 from the U937 macrophage cell line and the A549 lung epithelial cell line, respectively. In addition, PTFE-MPs activated the MAPK signaling pathways, especially the ERK pathway, in A549 and U937 cells, and in the THP-1 dendritic cell line. We also found that the expression of the NLRP3 inflammasome was reduced in the U937 and THP-1 cell lines following treatment with the PTFE-MPs sized 31.7 μm average diameter. Furthermore, expression of the apoptosis regulator, BCL2, was markedly increased in the A549 and U937 cell lines. Thus, although PTFE-MPs exert different effects on different cell types, our findings suggest that PTFE-MPs-associated toxicity may be specifically linked to the activation of the ERK pathway, which ultimately induces oxidative stress and inflammation.

Preparation technology and crystal structure analysis of NaNbO3 microcrystalline powders with different crystal orientations and morphologies by molten salt method

The different crystal orientations of NaNbO3 microcrystalline powders were synthesized by the molten-salt growth method with different precursors. The plate-like (001)-NaNbO3 orthogonal powders were synthesized by topochemical conversion using Bi2.5Na3.5Nb5O18 as precursor particles. The tabular NaNbO3 template particles were about 0.5–1 μm in thickness and about 15–25 μm in length. The rod-like (101)-NaNbO3 orthogonal powders were fabricated with Nb2O5 as a precursor. The preparation of Nb2O5 precursors required two processes: the molten salt method and the ion exchange method, respectively. The rod-like (101)-NaNbO3 orthogonal powders were about 0.6 μm in average diameter, and 8 μm in average length. The plate-like and rod-like orthogonal NaNbO3 powders had high aspect ratios. The diffraction peaks of plate-like NaNbO3 correspond to standards card JCPDS-33-1270, and its space group was Pbma. The crystal cell of Pbma NaNbO3 was a typical antiferroelectric structure. The diffraction peaks of rod-like NaNbO3 correspond to standard card JCPDS-86-0606, and its space group was P2lmc. The cell structure of P2lmc NaNbO3 was a typical ferroelectric structure.

High-throughput generation of uniform droplets from parallel microchannel droplet generators and the preparation of polystyrene microsphere material

To prepare uniform polystyrene particles with ten microns of diameter, a parallel scaling-up strategy for the capillary-assembled stepwise microchannel was developed, which created uniform droplets with high-throughput and formed a large amount of emulsion templates for the polymerization of styrene and cross-linker. The microchannel droplet generator was robust for the flow rate deviation of the continuous phase in the jetting flow, and droplet generation frequency up to 2.8 × 104 Hz was achieved with only four parallel droplet generators, which were much more efficient than the parallelly scaled microfluidic devices working in dripping flow. 32–52 μm average diameter droplets with 4.5%–8.4% diameter variation coefficients were successfully prepared from the microchannel device fabricated by low-cost 3D-print method, and the droplets were subsequently turned to solid particles via a two-step polymerization in the platform. The polystyrene particles were further reduced to 16.9–23.5 μm with 5.0%–8.6% diameter variation coefficients due to the accompanying emulsion polymerization, and the working capacity of the platform reached hundred milligrams of particles per hour.

The effect of heat treatment on pseudoelastic behavior of spark plasma sintered NiTi

Porous NiTi shape memory alloys are considered as artificial bio-materials for possible use in implant applications. Their extraordinary pseudoelastic response under uniaxial loading through phase change needs further analysis. The objective of this work is to show the effect of heat treatment on the pseudoelastic behavior of NiTi SMA produced by spark plasma sintering (SPS). NiTi samples were prepared from pre-alloyed Ti-50.7 at.% Ni powders of 100-150 μm average diameter, and subjected to a wide range of homogenization and/or aging at different temperatures and duration. Transformation characteristics of heat treated samples were obtained from DSC, their phase composition was identified using X-ray diffraction (XRD), and checked with scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Instrumented micro-indentation was carried out to measure the hardness altered by aging. Uniaxial compression tests were performed on heat treated samples, and their pseudoelastic behavior was shown on the stress–strain diagrams; the results showed a variation in pseudoelasticity. In general, Ni concentration of the matrix resulted in partial-pseudoelastic behavior of samples. Homogenization prior to aging improved the pseudoelasticity of the SPSed NiTi. The pseudoelastic response of the samples that have not shown the expected full pseudoelastic behavior was enhanced by applying a considerably long period of homogenization and aging.

First Report of Neopestalotiopsis clavispora Causing Calyx and Receptacle Blight on Strawberry in China.

Strawberry (Fragaria × ananassa) is widely cultivated in Liaoning Province, the most important strawberry production area in China. In November 2020, extensive brown spotting on the calyces and receptacles and dark brown necrotic lesions on the leaves of 'YanLi' strawberry plants were observed in the greenhouse, College of Horticulture, in Shenyang Agriculture University of Liaoning Province, China. The incidence ranged from 15% to 20% in the greenhouse. As the disease progressed, the spots extended to cover the entire receptacles and entire leaves. Fresh samples (5 mm2) were cut from the margin of healthy and infected tissues. The isolation and purification of methods were as described previously (Obregón et al. 2018). Fungal isolations are suborbicular with irregular edges. The colonies showed white aerial mycelium at the early stage and formed concentric circles after 5 days culture at 28°C on PDA. Black viscous acervuli appeared and scattered on the surface of the colony after 7~10 days culture. Acervulus was 162.4 µm in average diameter, n= 30. Conidia were spindle shape, five cells, four septa, 7.0 µm (average width) and 24.0 µm (average length), n=30. The apical and basal cells are lighter in color, most of them are hyaline, the middle three cells are darker in color, mostly brown. There are 2 to 4 colorless and transparent unbranched accessory filaments at the top, 30.8 µm in average length, and the basal cell has a small appendage, 9.0 µm in average length, n=30 (Fig. 1c-g). For fungal identification to species level, genomic DNA was extracted by the 2% CTAB method. Internal transcribed spacer (ITS) region, β-tubulin gene (TUB2) and translation elongation factor-1α (TEF-1α) were amplified (Qiu et al. 2020), respectively. Purified PCR products were sequenced in single direction. BLASTn searches of GenBank, using the partial ITS (MW861730), β-tubulin (MW856302) and TEF-1α (MW861729) sequences of representative isolate NP102 as the queries, revealed 97%, 100% and 100% sequence identity, respectively, to Neopestalotiopsis clavispora strain WJ31 accessions MG729690, MG740736 and MG740759. The phylogenetic tree was constructed by MEGA X (Fig. 2) (Kumar et al. 2018). Pathogenicity assay was carried out by spraying a spore suspension (1 × 106 spores/ml) of 8-day-old culture of fungus on six healthy 'YanLi' strawberry plants. An additional six control plants were only sprayed with sterile distilled water, and the inoculated plants were maintained in a light incubator at 25 ± 1°C, 90% relative humidity, with a photoperiod of 12 h. Calyx and receptacle blight and leaf spot symptoms resembled those observed in the greenhouse on all inoculated tissues after 10 days (Fig. 1h and i), whereas calyces, receptacles and leaves on control plants remained asymptomatic. The experiment was repeated twice. Neopestalotiopsis clavispora was successfully reisolated from the infected tissues, fulfilling Koch's postulates. Researchers in Spain (Chamorro et al. 2016) reported N. clavispora for the first time on strawberry. After two years, N. clavispora was found in Argentina (Obregón et al. 2018). The reports characterized it mainly as a root rot pathogen. In January 2021, Neopestalotiopsis spp. were reported that it is a pathogen of strawberry leaves and fruits in Florida strawberry fields (Juliana et al. 2021). Our studies indicated that isolate NP102 was more aggressive. In the warm and humid greenhouse, the disease struck suddenly at the early stages of strawberry fruiting. Unlike previous reports, symptoms were a calyx and receptacle blight as well as a leaf spot. This pathogen can cause serious economic losses to strawberry growers. To the best of our knowledge, this is the first report of calyx and receptacle blight by N. clavispora on strawberry in China.

Tuning intrinsic photoluminescence from light-emitting multispectral nanoporous anodic alumina photonic crystals

To control and harness the intrinsic photoluminescence of solid-state, light-emitting materials produced by self-organization approaches remain challenging. This study demonstrates how the intrinsic broadband photoluminescence emission from nanoporous anodic alumina (NAA) produced by anodization of aluminum in oxalic acid electrolyte can be precisely tuned by engineering its structure in the form of photonic crystals (PCs). A combination of pulse and constant anodization in distinct acid electrolytes makes it possible to engineer a novel heterogeneous optical structure consisting of two layers: (i) a non-emitting, light-filtering layer in the form of multi-spectral nanoporous anodic alumina photonic crystals (MS–NAA–PCs) on its top (i.e., 58 µm thick and average pore diameter of 17 nm) and (ii) an intrinsically light-emitting layer of NAA at its bottom (i.e., 50 µm thick an average pore diameter of 40 nm). MS–NAA–PCs are engineered to feature three intense, well-resolved photonic stopbands (PSBs), the positions of which are spaced at specific regions of the visible spectrum from ∼380 to 560 nm. It is demonstrated that the PSBs of the non-emitting MS–NAA–PCs on top of the heterogeneous optical structure act as a light-filtering component, which makes it possible to narrow and tune the characteristically broad, Gaussian-like photoluminescence emission from the underlying light-emitting NAA layer. This structural design makes it possible to narrow the width of photoluminescence emission up to ∼50 nm and blue shift its position for ∼15 nm. Our advances pave the way for novel designs of intrinsic, light-emitting NAA-based PC structures, which could find broad applicability across light technologies, such as sensing and biosensing, photodetection, and solar light harvesting.

Application of ultrasonic treatment for demulsification of stable water-in-oil emulsions

In this work, the prospects of using ultrasonic treatment together with a nanosized additive for destruction of stable water-in-oil emulsions of the W/O type of various compositions and properties, with 30–45 μm average diameter droplets, including those containing “gel”, are shown. The influence of such sonication parameters as power and exposure time on the separation efficiency of emulsion in batch mode has been studied. The research was carried out on ultrasonic devices of a submerged and a reactor type. It is shown that destruction above 99% of all the studied emulsions is achieved by using ultrasonic treatment with 1.0 kW power together with the addition of nanopowder AlN suspension in acetone. The exposure time comprised 0.5–3 min, the amount of the additive was equal to 4–8 %vol (depending on the composition and properties of the emulsion). The developed method of demulsification allows to obtain the oil phase with maximum water content of 0.5 wt% and the aqueous phase with maximum oil content of 46 mg L−1. Application of this approach leads to a significant decrease of oily waste formation.

Preparation of Silicon-Carbon-Graphene Composites and their Application to Lithium Ion Secondary Battery

Recently, high electrochemical performance anode materials for lithium ion secondary batteries are of interest. Here, we present silicon-carbon-graphene (Si-C-GR) composites for high performance anode materials of lithium ion secondary battery (LIB). Aerosol process and heat-treatment were employed to prepare the Si-C-GR composites using a colloidal mixture of silicon, glucose, and graphene oxide (GO) precursor. Fabrication of the Si-C-GR composites was composed of two stages. The first stage was formation of Si-glucose-GO composites by co-assembly of Si and GO while the sprayed droplets of the colloidal mixture went through the pre-heated aerosol reactor, and the second stage was carbonization of glucose and thermal reduction of GO by heat treatment. Morphology of as-fabricated Si-C-GR composites was generally the shape of a crumpled paper ball and the Si particles were well wrapped in carbon and graphene. The effects of the size of the silicon particles in Si-C-GR composites on the material properties including the morphology and crystal structure were investigated. Silicon particles ranged from 50 nm to 1 µm in average diameter were employed while concentration of silicon, graphene oxide and glucose was fixed in the aerosol precursor. The size range of composites was about from 2.2 to 2.9 µm. The composites including silicon particles larger than 200 nm in size exhibited higher performance as LIB anodes such as capacity and coulombic efficiency than silicon particles less than 100 nm, which were about 1500 mAh g–1 at 100 cycles in capacity and 99% in coulombic efficiency, respectively.

Tailor-designed nanowire-structured iron and nickel oxides on platinum catalyst for formic acid electro-oxidation.

This investigation is concerned with designing efficient catalysts for direct formic acid fuel cells. A ternary catalyst containing iron (nano-FeOx) and nickel (nano-NiOx) nanowire oxides assembled sequentially onto a bare platinum (bare-Pt) substrate was recommended for the formic acid electro-oxidation reaction (FAOR). While nano-NiOx appeared as fibrillar nanowire bundles (ca. 82 nm and 4.2 μm average diameter and length, respectively), nano-FeOx was deposited as intersecting nanowires (ca. 74 nm and 400 nm average diameter and length, respectively). The electrocatalytic activity of the catalyst toward the FAOR depended on its composition and loading sequence. The FeOx/NiOx/Pt catalyst exhibited ca. 4.8 and 1.6 times increases in the catalytic activity and tolerance against CO poisoning, respectively, during the FAOR, relative to the bare-Pt catalyst. Interestingly, with a simple activation of the FeOx/NiOx/Pt catalyst at −0.5 V vs. Ag/AgCl/KCl (sat.) in 0.2 mol L−1 NaOH, a favorable Fe2+/Fe3+ transformation succeeded in mitigating the permanent CO poisoning of the Pt-based catalysts. Interestingly, this activated a-FeOx/NiOx/Pt catalyst had an activity 7 times higher than that of bare-Pt with an ca. −122 mV shift in the onset potential of the FAOR. The presence of nano-FeOx and nano-NiOx enriched the catalyst surface with extra oxygen moieties that counteracted the CO poisoning of the Pt substrate and electronically facilitated the kinetics of the FAOR, as revealed from CO stripping and impedance spectra.

A Highly Sensitive Ammonia Gas Sensor Using Micrometer-Sized Core–Shell-Type Spherical Polyaniline Particles

A highly sensitive NH3 gas sensor based on micrometer-sized polyaniline (PANI) spheres was successfully fabricated. The PANI microspheres were prepared via a facile in situ chemical oxidation polymerization in a polystyrene microsphere dispersion solution, resulting in a core–shell structure. The sensor response increased as the diameter of the microspheres increased. The PSt@PANI(4.5) sensor, which had microspheres with a 4.5 μm average diameter, showed the largest response value of 77 for 100 ppm dry NH3 gas at 30 °C, which was 20 times that of the PANI-deposited film-based sensor. Even considering measurement error, the calculated detection limit was 46 ppb. A possible reason for why high sensitivity was achieved is simply the use of micrometer-sized PANI spherical particles. This research succeeded in providing a new and simple technology for developing a high-sensitivity NH3 gas sensor that operates at room temperature.

Ferulated Pectins from Sugar Beet Bioethanol Solids: Extraction, Macromolecular Characteristics, and Enzymatic Gelling Properties

Pectin from sugar beet (Beta vulgaris L.) (SBP) was extracted from a sugar beet waste (SBW) registering a 4.4% (w/w) yield. SBP presented a weight-average molar mass of 459 kDa, galacturonic acid content of 52.2%, and a low esterification degree (30%). The macromolecular characteristics of SBP revealed a flexible and extended coil chain conformation. The main neutral sugars in SBP were galactose (20.7%), mannose (5.0%), and arabinose (3.60%) while ferulic acid (FA) content was 2.1 µg·mg−1 sample. FA remained in the SBP chain mainly in RG I region even after suffering both, industrial processing and harsh weathering conditions. Consequently, SBP formed covalent gels induced by laccase. Covalent cross-linking content (dimers and trimer of FA) was 0.97 mg·g−1 SBP. The 8-5′, 5-5′, and 8-O-4′ dimers of FA isomers proportions were 75, 17, and 8%, respectively. SBP gels at 4% (w/v ) registered storage (G′) and loss (G″) moduli final values of 44 and 0.66 Pa, respectively. SBP gels were soft and adhesive according to texture profile analysis. Scanning electron microscopy analysis of SBP lyophilized gels revealed an imperfect honeycomb-like structure with 4.5 ± 1.4 µm average cavities diameter.