Scanning Electron Microscopy Methods Research Articles

Spectrophotometric-Based Assay to Quantify Relative Enzyme-Mediated Degradation of Commercially Available Bioplastics.

We present a spectrophotometric-based assay to identify enzymes that degrade commercially available bioplastics. Bioplastics comprise aliphatic polyesters with hydrolysis-susceptible ester bonds and are proposed as a replacement for petroleum-based plastics that accumulate in the environment. Unfortunately, many bioplastics can also persist in environments including seawater and waste centers. Our assay involves an overnight incubation of candidate enzyme(s) with plastic, followed by A610 spectrophotometry using 96-well plates to quantify both a reduction in residual plastic and the liberation of degradation by-products. We use the assay to show that Proteinase K and PLA depolymerase, two enzymes that were previously shown to degrade pure polylactic acid plastic, promote a 20-30% breakdown of commercial bioplastic during overnight incubation. We validate our assay and confirm the degradation potential of these enzymes with commercial bioplastic using established mass-loss and scanning electron microscopy methods. We show how the assay can be used to optimize parameters (temperature, co-factors, etc.) to enhance the enzyme-mediated degradation of bioplastics. The assay endpoint products can be coupled with nuclear magnetic resonance (NMR) or other analytical methods to infer the mode of enzymatic activity. Overall, the screening capacity of the spectrophotometric-based assay was demonstrated to be an accurate method to identify bioplastic-degrading enzymes.

Comparative Study on Leaf Anatomy in Selected Garcinia Species in Peninsular Malaysia

A comparative study of leaf anatomy was attempted on Garcinia species in Peninsular Malaysia to identify anatomical features useful in species identification and classification. The species are Garcinia mangostana var. mangostana , Garcinia mangostana var. malaccensis , and Garcinia celebica. Leaves were collected from two different regions: Kuantan, Pahang and Kepong, Kuala Lumpur. The leaf anatomical study was done using the methods of leaf peeling, leaf venation, leaf cross-section, and scanning electron microscopy. The assessment of the leaf anatomy found that these three Garcinia species showed similarities in anatomical features, including the presence of paracytic stomata on the abaxial surface, a straight to wavy anticlinal wall of both adaxial and abaxial surfaces, a thick cuticle wax layer, the presence of druses, mucilage canal, petiole vascular bundle, the presence of collenchyma cells in the midrib, and also the presence of sclerenchyma cells in midrib and petiole. Meanwhile, the notable anatomical variation observed in this study included three types of midrib vascular bundles: the outline of the leaf margin, the presence of tanniferous idioblast, leaf marginal, and laminal venation as six types of epicuticular waxes present on epidermal surface. Overall, this study highlighted the anatomical features that are taxonomically valuable, which could be used to identify selected Garcinia species in Malaysia.

A molecularly imprinted polymer-based electrochemical sensor for the determination of tofacitinib.

Tofacitinib citrate (TOF) is a Janus kinase-3 inhibitor used for rheumatoid arthritis treatment. In this study, a molecularly imprinted polymer (MIP)-based sensor was produced using acrylamide as the functional monomer via photopolymerization technique for the electrochemical determination of TOF. This study is the first one to explain the electrochemical determination of TOF with a highly selective MIP-based sensor. The surface characterization of the MIP-based sensor was performed with scanning electron microscopy and energy-dispersive X-ray spectroscopy methods, and it was expanded with electrochemical characterization by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) methods. TOF determination was performed using differential pulse voltammetry (DPV) and EIS methods in standard solution and spiked serum sample in the linear range between 1×10-11 M and 1×10-10 M. Very low limit of detection and limit of quantification values were found, confirming the sensitivity of the sensor. Recovery analysis with spiked serum and tablet samples verified the sensor's accuracy and applicability using DPV and EIS methods. The selectivity of the sensor was confirmed with imprinting factor and interference studies, and the sensor performance was controlled using non-imprinted polymer for comparisonat every step.

Authigenic greigite in late MIS 3 sediments: Implications for the Yellow Sea Cold Water Mass and Yellow Sea Warm Current evolution

Yellow Sea current conditions during the late Marine Isotope Stage 3 (late MIS3, 40–30 ka B.P.) highstand remain unknown. Here, environmental magnetism, geochemistry, particle size, and scanning electron microscope methods are employed to analyze core YS01A with a basal age of 40 kyr from the South Yellow Sea mud deposits. Greigite formed in marine sedimentary layers with thickness >7 m during early diagenesis. Greigite formation is related to the redox state and total organic content (TOC) availability, which are controlled, respectively, by the Yellow Sea Cold Water Mass (YSCWM) and the Yellow Sea Warm Current (YSWC). In MIS1 (7–0 ka B.P.), a strong YSWC brought greater TOC, and a strong YSCWM (thickness of 48 m) resulted in a strongly reducing low-oxygen environment. This led to massive magnetite dissolution and pyrite preservation. In late MIS3 (37–31 ka B.P.), the weak Kuroshio Current and East Asian Winter Monsoon (EAWM) resulted in a low-intensity YSWC that provided less TOC. A weak YSCWM (thickness of 35 m), caused by shallow water depths and a weak EAWM, contributed to a less reducing sedimentary environment. Thus, pyritization was interrupted and greigite was preserved. Greigite content can, thus, be used to trace the development of Yellow Sea currents. During a period of slow sea level rise at 41–37 ka B.P., minor greigite formed with most magnetite being preserved, which indicates that the environment started to become reducing. This can be interpreted as due to initial formation of a thin and weak YSCWM. During the 37–31 ka B.P. highstand, the greigite content increased, which suggests more reducing conditions related to establishment of a thicker and intensified YSCWM. In addition, the greigite content decreased progressively, which may have resulted from YSWC weakening. Our results suggest that greigite can be used as a simple tool to reflect current evolution in the Yellow Sea, which can give a better understanding of continental shelf environment change.

Synthesis, characterization and investigation of hydrophobic and self-cleaning properties of modified Zn–Mn and Cu–Mn nano spinels

Nano spinels of zinc-manganite and copper-manganite were synthesized by the co-precipitation method. Characterization of synthesized nanoparticles has been carried out using X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–vis diffuse reflectance spectroscopy (DRS), Field emission scanning electron microscopy (FESEM) and Atomic force microscopy (AFM) methods resulting in confirmation of the target phase formation performance of synthesized nanoparticles evaluated in photodegradation methyl red organic dye. In addition, synthesized nanoparticles were coated on sand-blasted glass and modified using palmitic acid to reach the hydrophobic surface. The contact angles of water droplets were measured for both surfaces which were 159° and 152° for zinc-manganite and copper manganite, respectively. The hydrophobicity of both coatings was available after 360 days making them a good candidate for the production of hydrophobic coating with photocatalytic activity in a blend with cement-like materials.

Corrosion Inhibition of Mild Steel and Aluminum in Hydrochloric Acid Solutions by Gum Exudates from Erythrophleum Africanum

The corrosion inhibition potentials of gum exudates extracted from Erthrophleum Africanum on mild steel and aluminium in acidic media were studied using gravimetric, Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) and potentiodynamic methods. The results range for gravimetric showed (30.30-80.0 %) and potentiodynamic polarization (66.50-86.74 %) which shows that the inhibition efficiency of the inhibitor increases with increase in concentration of gum exudate but decreases with increasing temperature. The addition of the gum exudate affects both the cathodic and anodic partial reaction, thereby reducing the cathodic and anodic current densities and the corresponding corrosion densities, which makes the gum act as a mixed type of inhibitor. The inhibitor was found to be an adsorption inhibitor that best fits the Temkim adsorption model; because the data have high degrees of linearity and the parameters were positive. The activation energy values ranges from 10 - 20 J/mol which indicates that the adsorption of the inhibitors favors the mechanism of physical adsorption, free energy of absorption ranges from -10.51 to -11.69 J/mol which indicate that the reaction is spontaneous and it’s an exothermic reaction. FTIR spectra of the inhibitors and the corrosion products of mild steel and Aluminum (in the presence of the inhibitors) revealed that there were shifts in frequencies of adsorption (821,925,1620,1730,1990) suggesting that some functional groups were used in adsorption and some new bonds were formed. (CH Rocking, = CH ‘oop’, C=O symmetric stretch) Examinations of the morphology of the mild steel and Aluminum (using SEM) before and after inhibition revealed the formation of protective coverage over the surface of the metal

Mesoporous Zn2SnO4 for efficient sensing of ethylene glycol vapor

Within this study, mesoporous Zn2SnO4 nanostructures have been prepared by a facile and eco-friendly hydrothermal method. Through X-ray diffraction analysis, a polycrystalline zinc tin oxide structure is recognized with a cubic inverse spinel phase crystal structure. By Field emission scanning electron microscopy method, various morphologies based on the hydrothermal time ranging from the cubic-like morphology, irregular hexagonal plates, and large quantity of microspheres to the truncated octahedron have been observed. By the aid of Energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analyses, the atomic ratio and characteristic vibration peaks of Zn2SnO4 have been evaluated. By the help of Brunauer–Emmett–Teller analysis, specific surface area, mean pore diameter, and total pore volume were measured. The nanostructured Zn2SnO4 prepared in 36 h hydrothermal treatment (as a selected sample) showed a higher BET specific surface area (9.10 m2/g) and total pore volume (0.078 cm3/g) than the other samples. The gas-sensing performance of the samples was investigated towards different vapors. The optimum operating temperature (270 °C), transient response, response/recovery times, and long-term stability (eight months) of the samples have been evaluated. For the selected sample, appreciable sensing response (92.92 toward 100 ppm ethylene glycol), the ultra-fast response time (1 s), excellent selectivity (about 6–23 times more than other tested vapors) and excellent long-term stability (the response decay of about 10% after eight months) has been perceived which makes it a promising gas sensor. It seems that the selected sample has shown relatively better performance for two reasons: Firstly, high crystalline quality (largest crystallite size and lowest strain value) which can affect the combination or separation of adsorbed oxygen species on the surface of the material. Secondly, the higher specific surface area and the relatively larger total pore volume can lead to more gas adsorption sites leading to further narrowing of the depletion layer and resulting in a high and very fast response.

A novel design of transitional layer structure between reduced activation ferritic martensitic steels and tungsten for plasma facing materials

Plasma-facing components (PFCs) are among the most critical gaps for fusion energy to establish technical and economic feasibility. Tungsten as a first wall/blanket material in PFCs requires to be integrating with reduced activation ferritic martensitic (RAFM) steels as a structural component. Currently, major drawbacks are the requirement of brazing, the formation of a brittle interface, and a large difference between the coefficients of thermal expansion of tungsten and steel. Here, a novel transitional multilayer structure was designed and investigated to join tungsten and RAFM steels using three interlayers. The composition of each interlayer was selected based on computational thermodynamics and diffusion kinetics to ensure a body-centered cubic (bcc) single-phase structure and prevent the formation of a brittle intermetallic phase region in the temperature range of 600–1150 °C. Although the transitional layer structure was designed for additive manufacturing, spark plasma sintering (SPS) as proof of concept was used to bond the individual layers. Interfaces were investigated using scanning and transmission electron microscopy methods but no layered intermetallic phase was observed. Nanoindentation maps across the interface suggest major hardness differences at the interface between tungsten and the vanadium interlayer, as well as the interface between RAFM steel and the FeCrAl interlayer.

Evaluation of in vitro coculture of keratinocytes derived from foreskin and adipose-derived mesenchymal stem cells (AMSCs) on a multilayer oxygen-releasing electrospun scaffold based on PU/PCL.Sodium percarbonate (SPC)-gelatine/PU.

Despite significant advancements in tissue engineering and regenerative medicine during the last two decades, the fabrication of proper scaffolds with appropriate cells can still be considered a critical achievement in this field. Hypoxia is a major stumbling block to chronic wound healing, which restrains tissue engineering plans because a lack of oxygen may cause cell death. This study evaluated the cocultured human keratinocytes and human adipose-derived mesenchymal stem cells (AMSCs) on a multilayer oxygen-releasing electrospun scaffold based on PU/PCL.Sodium percarbonate (SPC)-gelatin/PU. The scaffold was characterized using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) methods. Flow cytometry confirmed mesenchymal stem cells, and then the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay and DAPI staining were used to assess the in vitro biocompatibility of the scaffold. The experimental results showed that the multilayer electrospun scaffold containing 2.5% SPC could efficiently produce oxygen. Furthermore, according to cell viability results, this structure makes a suitable substrate for the coculture of keratinocytes and AMSCs. Gene expression analysis of various markers such as Involucrin, Cytokeratin 10, and Cytokeratin 14 after 14 days confirmed that keratinocytes and AMSCs coculture on PU/PCL.SPC-gelatin/PUelectrospun scaffold promotes dermal differentiation and epithelial proliferation compared to keratinocytes single-cell culture. Therefore, our study supports using oxygen-releasing scaffolds as a potential strategy to hasten skin tissue regeneration. Based on the results, this structure is suggested as a promising candidate for cell-based skin tissue engineering. Given that the developed oxygen-generating polymeric electrospun scaffolds could be used as part of a future strategy for skin tissue engineering, the PU/PCL.SPC-gelatin/PUhybrid electrospun multilayer scaffold in combination with keratinocyte/AMSC coculture is proposed as an effective substrate for skin tissue engineering and regenerative medicine platforms.

High-Resolution Imaging Methods for Identification of Calcium Crystal Types in Osteoarthritis

The detection and differentiation of BCP and CPP crystals in calcified tissue is an important factor in the context of research and potential future treatment of osteoarthritis and chondrocalcinosis. Current standard methods originate from clinical practice and often lack precision in the correct identification of the calcium crystal type. In this work, a step-by-step guide for the use of the high-resolution imaging methods of tissue sections, Raman spectroscopy and scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy (EDS), for calcium crystal identification is presented. Sample preparation including Von Kossa staining, measurement and measurement parameters, data processing and data analysis methods are discussed and described. Furthermore, the different methods are compared to show advantages and disadvantages. Overall, Raman spectroscopy is a reasonable method from an economic point of view and regarding the time/effort required for acquiring highly reliable data in calcium crystal identification. Potentially, semi-quantitative results can be obtained with little effort and without the destruction of the respective test sample. The analysis/penetration depth during the Raman measurements, which is not precisely defined, poses a potential problem for accuracy. SEM can also be used for this task but requires more time, advanced technical knowledge and a pre-treatment of the samples using, e.g., gold sputtering, which may distort further analysis on the specific specimen. Therefore, this technique yields additional value compared to Raman spectroscopy only with additional research questions needed to be answered in the same sample, such as analysis of the sample topography or analysis of other unknown particles/deposits using EDS. The methods described in this manuscript are helpful for retrospective analyses in the context of research, but can also be used for potential future treatment strategies to discriminate between osteoarthritis and chondrocalcinosis patients.

Low-temperature and single-step synthesis of fully-dense MgAl2O4 by reaction spark plasma sintering Al2O3 and MgO nano-oxides

The availability of commercial nano-powders and the rapidly maturing powder metallurgy technology have enabled researchers to develop advanced ceramics, with tailored microstructure and improved properties. However, a major challenge in the production of MgAl2O4, from Al2O3 and MgO, is the relatively high-volume expansion (5–8%) accompanying spinellization. This study demonstrates the possibility to prepare fully-dense and single-phase magnesium aluminate spinel, at low temperature and in short time, without the use of a sintering aid. This is achieved by sonication of magnesia and alumina followed by reaction spark plasma sintering. X-ray powder diffraction and scanning electron microscopy methods were used to characterize the starting nano-powders, sonicated powder mixture, spinel formation, and fractured specimens. The values of HV, K1c, and GIC were obtained from indentation measurements. The chemical composition, the SEM images, and the X-ray maps of magnesium and aluminum, confirmed the stoichiometry and homogeneity, at nano scale, of the densified specimens. The fully dense spinel, obtained at 1300 °C and 30 min, had average grain size of 40.92 nm, HV of 17.29 ± 0.185 GPa, K1c of 2.129 ± 0.106 MPa mm1/2, and GIC of 15.488 J/m2.

INVESTIGATION OF THE EFFECT OF HEAT TREATMENT ON Cu – Al ALLOYS OBTAINED BY WIRE-ARC ADDITIVE MANUFACTURING

By methods of optical, scanning and transmission electron microscopy, studies have been carried out to establish the influence of Al, Si andMg on the formation and change of the structure, phase composition and distribution of elements of Cu–Al alloys obtained by wire-arc additive manufacturing with cold metal transfer, and after their heat treatment. The main factors determining the mechanical behavior of Cu-Al alloys after the addition of Si and Mg and their heat treat- ment are determined and analyzed. It is shown that the increased strength and hardness of the Cu-Al alloy is explained by grain grinding and the formation of particles of the second phases between the layers of the deposited metal. The features of the distribution of the main elements (Cu, Al) and secondary elements (Si, Mg) in the process of wire-arc additive manufacturing are revealed. Recently, studies of the Cu-Al alloy have been carried out, which have shown that Al as a solid solution element in the Cu-Al alloy can increase the formation of deformation twins and the density of dislocations. In addition, it was found that the addition of micro-alloying elements to the Cu–Al alloy significantly improves its me- chanical properties. The kinetics of the growth of intermetallic compounds such as CuAl2, Cu9Al4, Cu3Al in Cu–Al casting alloys has been studied. As a result of the complex of technological measures, the modes of obtaining additive billets of Si–Al, Cu–Al–Si and Cu–Al–Si–Mg alloys were selected. Technological equipment has been improved to obtain blanks as part of the work. The microstructure, phase composition and mechanical properties of Si–Al, Cu–Al–Si and Cu–Al–Si–Mg alloys obtained bywire-arc additivemanufacturing using coldmetal transfer technology are investigated.

Effect of water saturation on dynamic behavior of sandstone after wetting-drying cycles

Fully understanding the influence of water on the rock materials' mechanical properties is of great significance to the safety design and evaluation in rock engineering. In this study, sandstone was pretreated with different wetting-drying cycles (0-15), and its pore characteristics were characterized by low-field nuclear magnetic resonance (LF-NMR) and scanning electron microscope (SEM) methods. Then, the split Hopkinson pressure bar (SHPB) tests with the same impact velocity were carried out in its dry and saturated states, respectively. The effects of water saturation on the dynamic behavior of sandstone under different porosity conditions and their mechanisms were emphasized. The results show that with the increase of cycle numbers, the porosity of sandstone increases, the dynamic strength and the total energy dissipation decreases. Moreover, the proportion of post-peak energy dissipation rises, and the degree of fragmentation intensifies. With the increase of porosity, the effect of water saturation on dynamic strength changes from enhancement to weakening. This may be related to the competition between the the Stefan effect and the contribution of pore water pressure. Finally, a dynamic damage constitutive model considering the coupling effect of the wetting-drying cycles and dynamic loads was established, and its effectiveness was verified.

ZnO Nanowires Grown on Al2O3-ZnAl2O4 Nanostructure Using Solid-Vapor Mechanism

We present Al2O3-ZnAl2O4-ZnO nanostructure, which could be a prominent candidate for optoelectronics, mechanical and sensing applications. While ZnO and ZnAl2O4 composites are mostly synthesized by sol-gel technique, we propose a solid-vapor growth mechanism. To produce Al2O3-ZnAl2O4-ZnO nanostructure, we conduct ZnO:C powder heating resulting in ZnO nanowires (NWs) growth on sapphire substrate and ZnAl2O4 spinel layer at the interface. The nanostructure was examined with Scanning Electron Microscopy (SEM) method. Focused Ion Beam (FIB) technique enabled us to prepare a lamella for Transmission Electron Microscopy (TEM) imaging. TEM examination revealed high crystallographic quality of both spinel and NW structure. Epitaxial relationships of Al2O3-ZnAl2O4 and ZnAl2O4-ZnO are given.

Increasing the Thermal Stability and High-Temperature Strength of Vanadium Alloys by Strengthening with Nanosized Non-Metallic Particles

Using the methods of scanning and transmission electron microscopy, the features of the structural-phase state of a vanadium alloy of the V-Cr-Ta-Zr system after a combined treatment, which consisted in cyclic alternation of thermomechanical and chemical-heat treatments, were studied. The values of yield strength and ductility of the V-Cr-Ta-Zr alloy were determined, depending on the stabilization and test temperatures. It was established that, after the combined treatment, the structural-phase state of the V-Cr-Ta-Zr alloy was composite, in which the joint implementation of dispersion and substructural strengthening ensured the formation of a gradient grain structure with a polygonal state, the elements of which were fixed by nanosized ZrO2 particles characterized by a high thermal stability. Such modification of the microstructure was accompanied by an increase in the high-temperature strength and a shift in the upper limit of the temperature stability interval towards high temperatures, of up to 900 °C. It was assumed that the polygonal state inside the grains contributed to the implementation of cooperative mechanisms of the dislocation-disclination type, which ensured the accommodation of the material in the "high-strength state" under loading.

Anatomical and morphological structure of the leaf of the genus Malus spp.

The article describes changes in the structure, leaves, (including mesophyll structure, structure of the midrib, distribution of stomata, and the number of vascular bundles) in Malus during the growing season (from June to August) under the influence of prolonged drought. The leaves anatomy and morphology were investigated by methods of light and scanning electron microscopy. The study was carried out on four representatives of the genus Malus: M. niedzwetzkyana Borkh., M. baccata ‘Pendula’, M. domestica ‘Eliza Rathke’, M. domestica ‘Renet Simirenko’. The influence of drought on the size of the mesophyll of the leaf plate and the number of stomata along the stretch from June to August was studied. The cell circumference of the sclerenchyma ranged from μm in 27.33 (M. niedzwetzkyana) to 81.92 μm (in M. domestica ‘Elise Rathke’). The number of stomata varied from 214.0 units in (M. domestica ‘Renet Simirenko’) to 304.0 units in (M. baccata ‘Pendula’), length from 11.6 μm (M. baccata ‘Pendula’) to 28.63 μm (M. domestica ‘Elise Rathke’), width from 9.4 μm (M. domestica ‘Elise Rathke’) up to 21.8 μm (M. domestica ‘Elise Rathke’) μm. The length of the trichomes varied from 409.92 μm (M. domestica ‘Renet Simirenko’) to 745.09 μm (M. niedzwetzkyana). Also, the anocytic stomatal type, the number, different stomata and trichomes, the presence of wax on the cuticle, and the found druses of calcium oxalate in M. baccata ‘Pendula’, can be important for systematic phylogeny. Thanks to these studies, it is possible to suggest physiological adaptability of apple trees to prolonged drought, as well as to identify more resistant phenotypes for the breeding process to develop resistant cultivars.

Compression-Softening Bond Model for Non-Water Reactive Foaming Polyurethane Grouting Material

In this study, the uniaxial compression and cyclic loading and unloading experiments were conducted on the non-water reactive foaming polyurethane (NRFP) grouting material with a density of 0.29 g/cm3, and the microstructure was characterized using scanning electron microscope (SEM) method. Based on the uniaxial compression and SEM characterization results and the elastic-brittle-plastic assumption, a compression softening bond (CSB) model describing the mechanical behavior of micro-foam walls under compression was proposed, and it was assigned to the particle units in a particle flow code (PFC) model simulating the NRFP sample. Results show that the NRFP grouting materials are porous mediums consisting of numerous micro-foams, and with the increasing density, the diameter of the micro-foams increases and the micro-foam walls become thicker. Under compression, the micro-foam walls crack, and the cracks are mainly perpendicular to the loading direction. The compressive stress-strain curve of the NRFP sample contains the linear increasing stage, yielding stage, yield plateau stage, and strain hardening stage, and the compressive strength and elastic modulus are 5.72 MPa and 83.2 MPa, respectively. Under the cyclic loading and unloading, when the number of cycles increases, the residual strain increases, and there is little difference between the modulus during the loading and unloading processes. The stress-strain curves of the PFC model under uniaxial compression and cyclic loading and unloading are consistent with the experimental ones, well indicating the feasibility of using the CSB model and PFC simulation method to study the mechanical properties of NRFP grouting materials. The failure of the contact elements in the simulation model causes the yielding of the sample. The yield deformation propagates almost perpendicular to the loading direction and is distributed in the material layer by layer, which ultimately results in the bulging deformation of the sample. This paper provides a new insight into the application of the discrete element numerical method in NRFP grouting materials.

Changes in the corrosion rate and microstructure of beta titanium wire using kiwi peel extract

Background: Beta titanium orthodontic wire is known to have good corrosion resistance but is weak in acidic environments, which advance the corrosion rate. One natural inhibitor that can be used to decrease corrosion is kiwi peel extract, which has a high antioxidant level. Purpose: This study aims to examine the ability of the extract to decrease the corrosion rate and microstructural changes of beta titanium at an acidic pH (pH 5). Methods: The samples used were beta titanium with a diameter of 0.016 x 0.022 in and a length of 6 cm. A total of 28 samples (n=28) were divided into four groups—a control group immersed in pH 5 artificial saliva and three treatment groups immersed in kiwi peel extract at concentrations of 400, 500, and 600 ppm (n=7), respectively. The samples were immersed for seven days at 37oC in an incubator. The corrosion rate was tested using the weight-loss method and microstructure change was analyzed using a scanning electron microscope (SEM). Results: One-way ANOVA showed that there are significant differences in corrosion rates between beta titanium immersed in artificial saliva and beta titanium immersed in kiwi peel extract with p=0.01 (p<0.05). SEM analysis results showed that the group with the least surface changes was the one immersed in 400 ppm of kiwi peel extract. Conclusion: Weight-loss and SEM methods show similar results. Kiwi peel extract proved to decrease the corrosion rate and changes in the microstructure of the wire most effectively at a concentration of 400 ppm.

Detection of Levofloxacin Using a Simple and Green Electrochemically Polymerized Glycine Layered Carbon Paste Electrode

The easy and rapid analytical tool, electrochemically polymerized (EP) glycine (GN) layered carbon paste electrode (LCPE), was used for the analysis of levofloxacin (LN) using cyclic voltammogram (CV) and differential pulse voltammetry (DPV). The surface features and activities of the electrochemical sensors EPGNLCPE and bare carbon paste electrode (BCPE) were analyzed using electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), CV and DPV methods. The modified sensor (EPGNLCPE)offers a vibrant and sensitive electrochemical LN oxidation peak by controlling overpotential and the electrode material fouling effect unlike BCPE. Under improved experimental conditions, the DPV method was used to analyze LN on EPGNLCPE by varying its concentration in 0.2 M phosphate buffer solution from 30 to 90 µM, resulting in a good linear relationship(between peak current and concentration), lower limit of detection (LOD: 8.436 × 10−7 M) and lower limit of quantification (LOQ: 2.812 × 10−6 M). Finally, real-time application of the sensor was tested by analyzing LN in medicinal samples, and good LN recovery was observed.

Zinc-doped sulfonated polyaniline tailored Multi-walled carbon nanotubes (Zn-SPANI-MWCNT); A novel nano-hybrid for designing a smart self-healable epoxy coating

In this study, the oxidized carbon nanotubes (MC) were functionalized with sulfonated polyaniline (SPi) and Zn cations (Z) via a layer-by-layer (LBL) method. The characterization of MC particles with and without inhibitors was done by Fourier-transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), Thermogravimetric analysis (TGA), and Field emission scanning electron microscopy (FE-SEM) methods. The active–barrier corrosion protection abilities of the coatings loaded with MC, MC.SPi, and MC.SPi.Z nano-carriers were evaluated by electrochemical impedance spectroscopy (EIS). The recorded logZ magnitudes at low frequencies for the MC.SPi.EP and MC.SPi.Z.EP samples were higher than 10, which illustrated that the loading of inhibitors on the MC could improve the distribution of nano-carriers in the coating and enhance the barrier index and stability of the coating. The EIS results attributed to the scratched coatings revealed that the MC.SPi.Z.EP total resistance was almost 8 times higher (83000 ohm.cm2) than the EP sample even after 72 hours. Higher adhesion and less penetration of corrosive agents into the interface of metal and coating were shown by pull-off and cathodic separation tests. In the cathodic separation test, the delamination of MC.SPi.Z.EP sample is reduced to 68% compared to EP, and also the pull-off strength is improved to 52%.