As a promising material for electromagnetic microwave absorption, FeSiAl (FSA) alloy always suffers from inadequate corrosion resistance in the marine environment. Herein, the Raman and X-ray ...photoelectron spectroscopy (XPS) depth profiling techniques are adopted to investigate the basic corrosion behavior of FSA in salt spray environment. The Raman analysis contributes to the understanding of the composition change at various corrosive periods while the XPS depth profiling reveals the corrosion process of Fe0→Fe2+→Fe3+ in a sequence. The observed corrosion rates (CRs) of FSA immersed in 5 wt% NaCl solution for 1, 24 and 48 h are 2.99 × 10−12, 4.90 × 10−12 and 5.85 × 10−12 m/s, respectively. The increasing value of CRs as a function of time demonstrates the accelerated corrosion tendency. Moreover, to suppress the corrosive behavior of FSA alloy, carbon is decorated on its surface by catalytic chemical vapor deposition method using acetylene as the carbon source. The carbon coating restrains the corrosion process by impermeability and hydrophobicity of carbon materials in corrosive mediums. This study will help in the designing of microwave absorbers which can resist corrosion in harsh reaction conditions as well as available at commercial level to save the economy.
•The corrosion behavior of FeSiAl was revealed through in-depth analysis of XPS.•The corrosion of FeSiAl evolves through valence variation of Fe0.→Fe2+→Fe3+.•Anti-corrosion performances of FeSiAl are enhanced with surficial atomic carbon layers.
•High quality PdSe2 crystal grown by the self-flux method.•The orthorhombic crystal structure quality and composition stoichiometry confirmed.•Intrinsic p-type carrier densities of ≈3.6 × 1017 cm−3 ...at room temperature measured.•2D layered structure with anisotropic properties confirmed.
Palladium diselenide (PdSe2) is an important transition metal dichalcogenide with a layers-dependent bandgap and many potential applications in electronic and optoelectronic devices. However, the availability of high-quality large-area crystals with phase control is still challenging. Herein, we report the successful growth of large-area PdSe2 single crystals using the self-flux method. The crystal structure, quality, and elemental composition were characterized by X-ray Diffraction, Energy-Dispersive X-ray Spectroscopy, and High-Resolution Transmission Electron Microscopy (HR TEM). The Raman-active vibrational modes of PdSe2 were identified using polarized Raman spectroscopy. The controlled synthesis of PdSe2 enables the potential for a broad range of heterostructures and further integrated optical and electro-optical applications.
The development of bio-based primary packaging is imperative to improve food safety and quality, along with mitigating the environmental pollution resulting from the increasing production of ...packaging wastes. Whey protein concentrate (WPC) has received significant attention as an alternative raw material for edible films production, whereas an area of many ongoing researches has been the inclusion of bio-based compounds to formulate functional edible films. This study elaborated the development of WPC edible films fortified with different essential oils (EO) to assess antimicrobial activity against gram-positive (Staphylococcus aureus and Listeria monocytogenes) and gram-negative (Salmonella enteritidis and Pseudomonas aeruginosa) food-borne pathogens. Subsequently, the effect of grafting bacterial cellulose nanowhiskers (BCNW) in film composites was evaluated for WPC/oregano EO (WPC/OEO) films, which showed the highest antibacterial activity. Notably, increasing the concentration of grafted BCNW entailed a proportional increase on the inhibitory activity. In specific, antibacterial activity increased up to 80% when 10% BCNW was grafted in WPC/OEO films. Inclusion of BCNW and homogenous distribution of OEO into the film blend was pointed out through Raman analysis. In addition, AFM and SEM analysis revealed that inclusion of BCNW and OEO into the film matrix led to the formation of rough films with pores. This structural change enhanced the release capacity of OEO, that was further confirmed through a release kinetic experiment. This study indicated that BCNW addition positively affected whey protein films properties, thereby envisaging the potential development of sustainable food packaging materials with tailor-made properties.
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•Films with oregano EO (OEO) exhibited high antibacterial activity.•Raman analysis confirmed the uniform distribution of OEO in film blends.•Bacterial cellulose nanowhiskers (BCNW) enhanced the release of OEO.•SEM, AFM analysis revealed changes of films porosity caused by OEO & BCNW.•Addition of BCNW enhanced antimicrobial activity.
It is now clear that growing flat graphene nanostructures from the gas phase on planar substrates is possible. One of the keys to success —particularly in producing a very large specific surface in a ...reduced space— is the use of 3D carbon nanostructures (i.e., vertical graphene nanowalls, VGNWs) over a planar substrate as a growth template for the deposition of electrochemically active materials (as, for example, transition metal oxides (TMO)). Vertical graphene nanowalls, also known as petal-like, vertical graphene flakes or vertical graphene, can achieve a very large specific surface area of 1100 m2/g, which is comparable to or greater than that of carbon nanotubes —the reference material for its use in high-performance supercapacitors or in other energy-related applications requiring a large active surface area. Vertical graphene nanowalls also exhibit high vertical and in-plane electrical conductivity when grown on metal electrodes, which benefits their use in electrochemical applications. Here, we focus on the growth of VGNWs on flexible stainless-steel substrates (SS310), in principle suitable for applications to electrodes of electrochemical systems (batteries, supercapacitors, catalysts), by inductively coupled plasma chemical vapour deposition (ICP-CVD), from methane as a carbon precursor, in a wide range of temperatures (575 to 900 °C). We will discuss the effect of growth temperature on morphological and structural characteristics of VGNWs based on the results of Raman spectroscopy and field emission scanning electron microscopy (FE-SEM) analysis. Because the nanostructures of graphene nanowalls reported to date are, for the most part, based on multi-layered graphene, here we seek to highlight the effect of temperature on the number of atomic layers of VGNW. In the 700–750 °C range, and under the plasma conditions explored, vertical graphene nanowalls are bilayer, which is foreseen to directly affect the magnitude of the VGNW specific surface.
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•Growth of graphene nanowalls by ICP-CVD on stainless steel in the range 675–775 °C.•Monatomic two-layer graphene nanowalls grown at 750 °C by ICP-CVD.•Defects mainly at the edges and not at the faces of the graphene nanowalls.•Easy anchorage of MeOx particles on edges and high chemical stability of the system.
•Impact microindentation measures tissue-level properties of cortical bone in vivo.•The nature of the measured properties is incompletely understood.•We analyzed iliac crest bone biopsies obtained ...concurrently with IMI measurements.•Nanoporosity and Pyridinoline content are important determinants of BMSi.
Impact microindentation (IMI) is a Reference Point Indentation technique measuring tissue-level properties of cortical bone in humans in vivo. The nature, however, of the properties that can affect bone strength is incompletely understood. In the present study we examined bone material properties in transiliac bone biopsies obtained concurrently with measurements of Bone Material Strength index (BMSi) by IMI in 12 patients with different skeletal disorders and a wide range of BMD, with or without fractures (8 males, 4 females, mean age 48±12.2 (SD) years, range 15–60 years). IMI was performed in the mid-shaft of the right tibia with a hand‐held microindenter (OsteoProbe). Cancellous and cortical bone mineralization density distributions (BMDD) were measured in the entire biopsy bone area by quantitative backscattered electron imaging. Raman measurements were obtained right at the outer edge of the cortex, and 5, 50, 100, 500μm inwards. The calculated parameters were: i) Mineral and organic matrix content as well as the mineral / matrix ratio. ii) Nanoporosity. iii) Glycosaminoglycan content. iv) Pyridinoline content. v) Maturity/crystallinity of the apatite crystallites. There was no relationship between BMSi values with any measurement of mineral content of whole bone tissue (BMD, BMDD) or maturity/crystallinity of bone mineral. On the other hand, a positive correlation between BMSi and local mineral content, and an inverse correlation between BMSi and nanoporosity at the mineralized subperiosteal edge of the sample and at 5μm inwards was found. A positive correlation was also observed between BMSi and pyridinoline content at the same locations. These results indicate that local mineral content, nanoporosity and pyridinoline content at the subperiosteal site in the transiliac bone biopsy are linked to the BMSi values measured in the tibia. As both high porosity at the nano level and low pyridinoline content of the bone matrix can negatively impact bone strength, our findings suggest that BMSi most likely assesses subperiosteal bone material properties.
•The significant influence of the focus position on laser machining was theoretical analyzed and experimental verified.•In laser machining with enough pulse energy, the ablation width was mainly ...determined by the laser propagation properties.•The ablation depth would achieve the maximum value at a defocusing position rather than the focal plane.•Graphitization was discovered on the laser machined diamond surface and the graphite fraction would be enhanced after the defocusing quantity exceeding 45 µm.•Micro-structures with different patterns and structuring ratios were successfully fabricated on diamond surface just by adjusting the focus position.
Micro-structured surface on diamond is widely used in microelectronics, optical elements, MEMS and NEMS components, ultra-precision machining tools, etc. The efficient micro-structuring of diamond material is still a challenging task. In this article, the influence of the focus position on laser machining and laser micro-structuring monocrystalline diamond surface were researched. At the beginning, the ablation threshold and its incubation effect of monocrystalline diamond were determined and discussed. As the accumulated laser pulses ranged from 40 to 5000, the laser ablation threshold decreased from 1.48 J/cm2 to 0.97 J/cm2. Subsequently, the variation of the ablation width and ablation depth in laser machining were studied. With enough pulse energy, the ablation width mainly depended on the laser propagation attributes while the ablation depth was a complex function of the focus position. Raman analysis was used to detect the variation of the laser machined diamond surface after the laser machining experiments. Graphite formation was discovered on the machined diamond surface and graphitization was enhanced after the defocusing quantity exceeded 45 µm. At last, several micro-structured surfaces were successfully fabricated on diamond surface with the defined micro-structure patterns and structuring ratios just by adjusting the defocusing quantity. The experimental structuring ratio was consistent with the theoretical analysis.
This study summarizes the concentration in dry weight (dw) of several metal(oid)s (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn), as well as the abundance and characteristics of microplastics (MP) in wet ...weight (ww) of the soft tissues of clam Corbicula fluminea from Chubut River (Patagonia, Argentina). The contents of essential elements were in the following decreasing order: Zn > Mn > Cu > Ni; meanwhile, non-essential elements Cd, Cr and Pb were below the detection limit (<0.5 μg/g dw). A high mean concentration of As (6.1 ± 0.3 μg/g dw) was found, surpassing the maximum allowable limit established by the Argentine Food Code for bivalve molluscs. The number of MP ranged from 0.07 to 1.27 items/ind. and from 0.2 to 2.9 items/g ww. Fibers were the most common shape, mainly transparent. The size of MP ranged from 42 to 1917 μm, accounting for 62 % of MP between 50 and 450 μm. The dominant polymer was PET based on the results of Raman spectroscopy. Based on the widespread distribution of MP in the environment and the wide range of effects on organisms, it is necessary to develop long-term monitoring programs for MP contamination in different environmental matrices. Understanding the bioaccumulation of MP in bivalves is crucial to assess the potential risk to human health through consumption and to the ecosystem. We propose that the widespread Asian clam could serve as a useful biomonitor for MP and As pollution in freshwater and estuarine environments such as the Chubut River.
•Essential metals contents in C. fluminea were Zn > Mn > Cu > Ni.•Cd, Cr and Pb were below detection limit (<0.5 μg/g).•Arsenic could represent a risk to human health associated to clam's consumption.•Transparent fibers of PET in the size range of 50–450 μm were the most abundant MP.•Asian clam is a good biomonitor of pollution that can occur in the environment.
In pursuit of manufacturing of carbon nanotubes (CNTs) in good yield at lower temperatures, a mixture of d-block elements such as Iron, Nickel, and Cobalt was expected to be advantageous because of ...the high yield and low temperature (at 220 - 250° C) synthesis. The physical state and aggregation of these catalyst particles in the reaction medium have been found to play an interesting role in obtaining CNTs at better yield. Carbon nanotubes have been successfully produced by an uncomplicated two-step solvothermal method between sodium and dichlorobenzene via Ni/Fe/Co as catalyst precursor. The dependence of yield of CNTs on the catalyst system was determined via different ratios of catalysts and at various other experimental conditions such as different heating temperatures, different durations of heating. The X-ray powder diffraction study has indicated the graphite kind of the products. Microscopic characterizations (SEM and TEM) implied us the diameters of carbon nanotubes are 10-14 nm. Raman spectroscopy shows the presence of graphitized carbon in carbon nanotubes. Significant influence by the heating temperature and heating duration has been observed on the product yield.
The improper disposal of pharmaceuticals can disrupt aquatic ecosystems in rivers and lakes, as well as impact human and animal health. Consequently, heterogeneous photocatalysis stands as a ...promising technology to mitigate or even eradicate these pollutants from aquatic systems. Silver phosphate crystals (Ag3PO4) exhibit exceptional photocatalytic and bactericidal properties. Ag3PO4 crystals were synthesized using the precipitation method, followed by a 6h heat treatment at temperatures of 100, 200, 300, 400, and 500 °C. X-ray diffraction data showcase structures with outstanding crystallinity, which remain stable even under fluctuating temperatures. Scanning electron microscopy images reveal shifts in material morphology as the temperature rises. Diffuse reflectance spectroscopy unveils optical band energy values ranging from 2.33 to 2.41 eV for the materials. Conversely, both Raman and infrared spectra indicate a reduction in bands linked to phosphate groups. Lastly, Ag3PO4 crystals exhibited remarkable performance in the photodegradation of 17α-ethinylestradiol (EE2) during a 280 min test, achieving removal rates of 77.5 %, 71.2 %, 92.4 %, 82.0 %, 41.3 %, and 92.5 % for crystals treated at 25, 100, 200, 300, 400, and 500 °C, respectively. Ag3PO4 crystals treated at 200 and 500 °C demonstrated the highest photocatalytic efficiency, attributed to their enhanced structural and morphological properties.
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•Raman spectra showed short-range variation with temperature variation, indicating surface amorphization.•The heat treatment at 500 °C promoted a significant morphological evolution in the Ag3PO4 crystals.•Ag3PO4 crystals treated at 200 and 500 °C removed more than 90 % of EE2 from the aqueous solution in 280 min.
Present work reports the preparation of WO3 nanoparticles through facile and efficient hydrothermal route. Raman analysis confirms the formation of monoclinic WO3 phase. Scanning electron microscope ...(SEM) analysis shows that the WO3 samples consists of nano sized particles having uniform distribution and UV–vis-NIR analyses shows absorption in the visible region. Dynamic Light Scattering (DLS) experiments reveal that WO3 nanoparticles have zeta potential of −12.9 mV and electrophoretic mobility of −6.7 × 10−5 cm2/Vs in water. Value of zeta potential confirms that the sample is moderately stable at room temperature. Also these WO3 nanoparticles showed significant sonocatalytic property in methylene blue (MB) solution. WO3 nanoparticles having a concentration of 1 g/L shows a noteworthy 61.2% of removal efficiency on water containing MB dye concentration of 10 mg/L within 90 min.
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