Field Emission-scanning Microscopy Research Articles

Determination and standardization of the kefiran extraction protocol for possible pharmacological applications

The use of biopolymers in medicine and pharmacology is of great scientific, technological, and commercial interest. A possibility of biopolymer for use in pharmacological applications is the kefiran, an exopolysaccharide (EPS) produced by bacteria that form kefir grains during the milk fermentation process in which the grains are growing. The EPS extraction method can modify its concentration and structure. To establish the most appropriate kefiran extraction protocol and standardize this method, three different extraction processes were evaluated, which differ in the boiling times and in the presence (or not) of agitation. Kefiran obtained by different methods were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), electron scanning field emission microscopy (FESEM), and determination of antimicrobial potential. The samples showed differences in yield, chemical composition, degree of purity, thermal properties, and antimicrobial capacity. The results analyzed indicated that extraction protocol 1 (EP 1) with a longer heating time and constant agitation was able to provide the best thermal resistance, with a high degree of purity (93%), and yield (22.18 mg of kefiran obtained for each gram of kefir grains used). In addition, this method provides good biological activity as a potential antimicrobial agent and can be a potential biopolymer for pharmacological application.

Effect of post heat treatment on surface properties of hydrogen peroxide (H2O2) treated titanium

In this study different heat treatment temperatures have been applied for titanium implant after surface modification through chemical treatment by Hydrogen Peroxide (H2O2). X-ray diffraction (XRD) analysis revealed that the main phase at the surface of heat-treated sample at temperatures below than 650 °C is Anatase, moreover, the presence of Anatase, which is dominate along the Raman shift, with noticeable pick intensity is confirmed by Raman spectroscopy technique. Field emission scanning microscopy (FESEM) observation shows that by increasing temperature, the porous structures did not change significantly in terms of morphology. Contact Angle (CA) measurement and Ellipsometry are other techniques which are used to figure out hydrophobicity of the surface and optical properties of the oxide surface, respectively.

Electro fabrication of molecularly imprinted sensor based on Pd nanoparticles decorated poly-(3 thiophene acetic acid) for progesterone detection

In recent years, scientific community has witnessed substantial interest in the design and engineering of electrodes as sensing platforms towards sensitive and selective detection of hormones. An electrochemical strategy for the detection of progesterone was proposed by generating a composite film comprising of palladium nanoparticles with 3-thiophene acetic acid (3-TAA) coupled with molecular imprinting technology. Progesterone molecule was employed as the template while generating molecular imprints by electropolymerization on the surface of the Carbon Fibre Paper (CFP) electrode. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to analyse the various modified working electrodes (CV). Characterization methods included field emission scanning microscopy, energy dispersive X-ray spectrometry, optical profilometry, and X-ray photon electron spectroscopy. Pd nanoparticles resulted in enhanced sensitivity and molecular imprinting technology contributed to its specificity. Because of the molecular cavities created on the removal of the template molecule, Nyquist plots data showed that the MIP/Pd/CFP electrode had the lowest charge transfer resistance compared to other control electrodes.

Influence of zinc oxide/expanded vermiculite composite on the rheological and anti-aging properties of bitumen

The bitumen modifier, zinc oxide (ZnO)/expanded vermiculite (EVMT) composite (ZnO/EVMT), was introduced into the bitumen with a dosage of 4%, 5%, and 6%. The surface morphology of EVMT and ZnO/EVMT was characterized by a field emission scanning microscope (FESEM). Further, the Superpave continuous grade of bitumen containing different amounts of ZnO/EVMT was determined by the dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test. The bitumen samples were aged by thin film oven test (TFOT), pressure aging vessel (PAV) aging test and ultraviolet (UV) aging test, and the influence of different amounts of ZnO/EVMT on both physical and rheological properties of the bitumen before and after aging were investigated. Moreover, the influence of ZnO/EVMT on the molecular distribution during aging was investigated by analyzing the change in the proportion of large molecular size (LMS) obtained from gel permeation chromatography (GPC). The FESEM result shows the ZnO particles are uniformly supported on the EVMT surface. Moreover, ZnO/EVMT slightly influences the high-temperature performance and improves the low-temperature cracking resistance of bitumen. In addition, no matter what aging method is adopted, ZnO/EVMT effectively increases the retained penetration and phase angle aging index, and decreases the viscosity aging index and complex modulus aging index of the bitumen, demonstrating the effectiveness of ZnO/EVMT in both resisting the thermo- and photo-oxidative aging of bitumen. Meanwhile, 6% and 4% ZnO/EVMT exhibit the best inhibitory effect on thermo- and photo-oxidative aging of bitumen, respectively. According to the GPC results, the composite inhibits the transformation of small molecules to large molecules during aging, resulting in a lower LMS increment and better anti-aging properties of the modified bitumen.

One-dimensional self-assembled Co2SnO4 nanosphere to nanocubes intertwined in two-dimensional reduced graphene oxide: an intriguing electrocatalytic sensor toward mesalamine detection

The present work deals with the preparation of hybridized electrode material with electrostatic self-assembly strategy for mesalamine (MES) detection. Grabbing significant abilities between the one-dimensional bimetallic oxides and two-dimensional nanosheets network, a nanohybrid was designed. The developed cobalt stannate/reduced graphene oxide (Co2SnO4/rGO)-1D/2D heterostructure will possess improvised anisotropic electron transport, earth abundant, highly conducting, multiple actives site, and higher surface area. The 1D/2D nanostructured architecture will enhance faster electron and mass transport during the electrochemical analysis, which is more significant for MES detection. Progressive testing of Co2SnO4/rGO for structural analysis was done, and highly crystalline nature was proved. The self-assembled nanospheres to form nanocube such as Co2SnO4 strongly attached over the rGO matrix was confirmed with field emission scanning microscope, and nanocube structure is more visible with high-resolution transmission electron microscopy. The hierarchical highly electroactive material establishes lower detection limit at 4.9 nM with sensitivity of about 8.57 μA/μM/cm2. The interfacial area of nanocomposite with higher conducting channels to improve the interactions with MES resulted in enhanced selectivity. The practical analysis in environmental, pharmaceutical, and biological fluids (human urine and serum) showed good recovery. The Co2SnO4/rGO will be more prominent and significant as electrode material in electrochemical sensing.

Fabrication of Fe3O4-incorporated MnO2 nanoflowers as electrodes for enhanced asymmetric supercapacitor performance.

Manganese dioxide (MnO2) is considered a promising aspirant for energy storage materials on account of its higher theoretical capacitance along with low capital cost. However, its performance is generally limited by its poor lifespan and intrinsic conductivity. In this study, MnO2-incorporated iron oxide (Fe3O4) nanoflowers were synthesized through a facile hydrothermal route and their electrochemical performance was probed. The surface composition and morphology of the as-synthesized samples were confirmed using X-ray diffraction, X-ray photoemission spectroscopy, and field emission scanning microscopy. The nanoflower-like structure and synergistic effect between the two oxides of the as-prepared MnO2@Fe3O4 nanocomposite electrode result in desirable surface area and intrinsic conductivity. Owing to its higher surface area and electrical conductivity, the MnO2@Fe3O4 nanoflower-like nanocomposite exhibits an enhanced specific capacitance (Cs) of 1651 F g-1 (1 A g-1) in a three-electrode test cell, which is two-fold higher than those of pristine Fe3O4 and MnO2. In addition, an asymmetric supercapacitor (ASC) was readily constructed by sandwiching a cellulose membrane (separator) between MnO2@Fe3O4 (cathode) and activated carbon (anode). Significantly, the ASC displayed a high Cs of 131 F g-1 (1 A g-1) along with a pretty high cycling stability of 96% over 5000 cycles at 15 A g-1 and a high energy density of 46.6 Wh kg-1 at 0.8 kW kg-1. These results demonstrate the significant potential of the MnO2@Fe3O4 nanoflower ASC device for state-of-the-art futuristic advanced energy storage applications.

Altered mesopore distribution in exfoliated WS2 nanosheets with radiation exposure

The existence of nano-dimensional meso-macro pores, and an enhancement in the porosity resulting in improved photocatalytic activity have been witnessed in the WS2 material upon radiation exposure (UV and β–rays). Moreover, the N2 adsorption/desorption isotherms exhibit type-IV characteristics. Through the field emission scanning microscopy (FE-SEM), the thin layered sheets of the nanosystem can be seen with adequate exfoliation as compared to their bulk counterpart. Furthermore, the Raman spectra were analyzed for excitation with different laser powers (∼0.25–2.5 mW), for every system under study signifying a higher E12g/A1g intensity ratio at lower power of excitation in the case of exfoliated nanoscale WS2 system.

Magnetic nanoparticles embedded microcryogels for bilirubin removal

In this study, for the first time, micro-engineered cryogels embedded with Fe3O4 nanoparticles were developed as magnetic adsorbents. Magnetically controllable microcryogels were produced on a microstencil array chip by cryopolymerization and functionalized by polyethylenimine, as an affinity ligand. Macroporous architecture of both magnetic and non-magnetic microcryogels were evaluated via field emission scanning microscopy. Bilirubin adsorption studies were performed to investigate the optimal removal conditions. The results indicated that the adsorption capacity of magnetic microcryogels increased with higher temperature values while decreased with higher salt concentrations. Plasma bilirubin removal assay showed that the removal of MMs-PEI was much higher (i.e., 13-fold) than that of MMs. Magnetic microcryogels exhibited significant reusability, where the adsorption capacity decreased by 7.8 % after 5 adsorption-desorption cycles. The results showed that magnetic micro-engineered cryogels provided good application potential for bilirubin removal and an alternative for the current methods.

Influence of Temperature on Structural and Magnetic Properties of Gd3AlxFe5−xO12 (x = 2)

AbstractThis research work explores the effect of sintering temperature on morphology and magnetic properties of aluminum substituted gadolinium iron garnet Gd3AlxFe5−xO12 (x = 2). Sol–gel autocombustion method is adopted to prepare Gd3AlxFe5−xO12, and further sintered at 900, 1000, and 1100 °C. X‐ray diffraction (XRD) confirms the formation of garnet phase structure. Fourier transformation infrared ray further stands with result of XRD that reveals the presence of garnet phase. Field emission scanning microscope analysis shows the formation of average grain size 4, 6, and 13 nm for 900, 1000, and 1100 °C, respectively. Vibrating sample magnetometer results show that the coercivity decreases with increases in temperature, which indicates that this material can be used in switching devices. The calculated value of microwave operating frequency reveals that these materials can be used in ultrahigh‐frequency region.

Enhanced sensitivity of low-cost fabricated fluorine doped ZnO metal semiconductor metal photodetector

The literature mostly reports on thin-film fluorine-doped zinc oxide (FZnO) and has yet to fabricate metal semiconductor metal (MSM) photodetectors (PDs) based on FZnO nanostructures for the enhancement of photoresponse parameters despite their huge potential. In this work, ZnO film of 32 nm-thick was deposited and used as a seed layer on silicon (Si) substrates with the aid of the radio frequency (RF) magnetron sputtering method. Vertically well-aligned FZnO nanorods (NRs) were later grown on the seeded substrates via a hydrothermal method and annealed for 1 h at 400 °C. The formation of well-aligned hexagonal NRs at low fluorine doping was revealed by field emission scanning microscopy (FESEM), and energy-dispersive X-ray (EDX) analysis confirmed the presence of fluorine doping. X-ray diffraction (XRD) investigation confirmed the growth of good crystal quality hexagonal wurtzite F–ZnO NRs along the (002) direction, and bandgaps were estimated using UV–Vis–NIR spectroscopy. Photoluminescence (PL) measurement has revealed the main emission peak for ultraviolet (UV) is centered at 375 nm and a red-shifted emission with fluorine doping has been identified. An F2 UV MSM PD device is fabricated. Upon exposure to UV light (395 nm) at 4 V, it displayed a high sensitivity of 1.1 × 105%, responsivity of 0.66 A/W, detectivity of 1.30 × 1010 Jones, a response time of 90 ms, and recovery time of 110 ms.

Preparation and Characterization of NiTi/PVA Nanofibers by Electrospinning

NiTi alloys are widely used in biomedical applications for their unique properties particularly the shape memory effect, superelasticity, and biocompatibility. In this research, NiTi/PVA composite nanofibers are fabricated by electrospinning technique, using a novel method of producing NiTi ultrafine particles by immersing amorphous NiTi alloy in dilute aqua regia solution. The NiTi particles are successfully embedded in the PVA matrix. The produced NiTi particles are analyzed by X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS), and Particle size analyzer. The XRD pattern of ultrafine NiTi particles shows much better phases as compared to the XRD pattern of the amorphous NiTi alloy sample. The morphology of the produced NiTi/PVA composite nanofibers are characterized by Field emission scanning microscope (FESEM), and Energy dispersive spectrometry (EDS). The test results show regular continuous smooth bead-free nanofibers.

Sensitive detection of Penicillin-G chemical using SnO2.YbO nanomaterials by electrochemical approach

In this approach, binary tin oxide doped ytterbium oxide nanosheets (SnO2.YbO NSs) were synthesized in an alkaline phase using under low-temperature facile hydrothermal technique. Traditional methods such as UV–Visible spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), Powder X-ray diffraction (XRD), Field Emission Scanning Microscopy (FESEM) equipped with X-ray electron dispersive spectroscopy (XEDS), and X-ray photoelectron spectroscopy (XPS) were used to fully characterize the prepared SnO2.YbO NSs. Fabrication of a thin-coating with doped NSs onto GCE by using 5% nafion conducting binder resulted in development of a selective and enzyme-free penicillin-G sensor probe. A reliable I-V technique was used to perform electrochemical performances of good sensitivity, large LDR, and long-term stability of the desired Penicillin-G sensor (SnO2.YbO NSs/GCE/Nf). With a wide range of Penicillin-G concentration, the proposed calibration plot is noticed good linearity (R2 = 0.9830). Sensitivity and LOD of the sensor were calculated as 24.75 μAμM-1cm−2 and 30.0 pM, respectively based on S/N = 3 formula. Real samples (Human and rabbit serum, milk, and red-sea water) were analyzed with the fabricated SnO2.YbO NSs/GCE/Nf sensor probe and the findings results were acceptable and satisfactory. This approach could be a noble development of in-situ Penicillin-G sensor based on binary SnO2.YbO NSs/GCE/Nf by reliable I-V technique for important sensing applications including beneficial doped nanomaterials and nano-technological system.

Structural analysis of silicon carbide prepared from two types of carbon sources

Silicon carbide (SiCcs and SiCdk) powders have been prepared from Murzuq silica sand (fine silica) as a silica source(Mws), citrus Sinensis tree branches (cs), and dates kernels (dk) taken as carbon sources for industrial applications. The sol–gel method was employed to prepare the samples. The samples were calcinated in a bath containing silica/carbon mixture for 6 h. The X-ray diffraction (XRD) results revealed that both samples with different carbon sources contained three polytypes of 6H, 21R, and 3C-SiC. The morphology of the samples has been measured using the field emission scanning microscope (FE-SEM). Large particles accompanied by thin rod-like structures with average lengths between 0.3 and 2 μm were observed for the SiCcs sample. The morphology of the SiCdk sample showed large particles and some holes. Raman spectra of both samples showed peaks located at 1356 cm−1 and 1596 cm−1 related to D and G peaks, respectively.

On an iridescent film of carbon nitride grown on an aluminum sheet and composed of overlapped oak-leaf shaped nanoparticles

An iridescent carbon nitrogen film g-C3N4 was formed by chemical vapor deposition (CVD) on an aluminum sheet starting from melamine cyanurate as a precursor at a temperature of 600 °C. The film was easily detached and thoroughly characterized using various techniques, including X-ray powder diffraction, UV − Vis and infrared spectroscopies, and field emission scanning microscopy. The material exhibited a particular layered microstructure consisting of stacks of nano-/micro-sized oak-leaf-shaped particles. The UV − Vis spectrum exhibited two defined bands corresponding to localized electrons; however, the apparent direct bandgap was 3.1 eV, similar to that of bulk g-C3N4. The IR spectrum was similar to that of bulk material, with differences in band intensities of the bending zone of tri-s-triazine units, in the range of 900 − 800 cm−1. The 2 D unfolding of the material with the formation of a thin layer composed of oak-leaf-like particles led to structural iridescent colors. For this reason, applications in optoelectronics and photovoltaic cells based on thin films prepared by the reported synthesis route may be envisaged, taking advantage of the properties of structural colors.

Preparation and Microstructure Analysis of Continuous Unidirectional Solidification Cu–P–Sn Alloy

Cu–10% P–6% Sn alloy rods with columnar crystal structure were synthesized in this study utilizing Cu–10% P–6% Sn alloy as the starting material. Continuous directional solidification was used to produce Cu–10% P–6% Sn (mass percentage) alloy rods with a diameter of 8 mm, and the heat treatment procedure was arried out under the condition of cast alloy. Optical microscopy and field emission scanning microscopy were then used to investigate the microstructure of the cast alloy. The impact of heat treatment on microstructure evolution was also investigated. The microstructure of a Cu–10% P–6% Sn alloy produced by continuous directed solidification had a Cu-rich dendritic structure, and the second phase structure was linear or spherical, according to the findings.

Magnetic solid-phase extraction of high molecular weight peptides using stearic acid-functionalized magnetic hydroxyapatite nanocomposite: determination of some hypothalamic agents in biological samples.

Therapeutic peptides have an important effect on physiological function and human health, so it is momentous to quantify and detect low levels of these biomolecules in biological samples for treatment and diagnostic purposes. In the present study, an efficient magnetic solid-phase extraction (MSPE) method was developed based on stearic acid-functionalized magnetic hydroxyapatite nanocomposite (MHAP/SA) as a novel and cost-effective adsorbent for extraction of five hypothalamic-related peptides (goserelin, octreotide, triptorelin, somatostatin, and cetrorelix) from biological samples. To characterize the morphology and physicochemical properties of MHAP/SA, Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), field emission scanning microscopy (FE-SEM), CHNS elemental analysis, Brunauer-Emmett-Teller (BET), and vibrating sample magnetometry (VSM) were applied. Under optimum conditions, the proposed method (MSPE-HPLC-UV) represented favorable linearity with R2 ≥ 0.9987, suitable intra- and inter-day precisions (RSD ≤ 6.9% and RSD ≤ 8.1%, respectively, n = 3), and limits of detection and quantification in the range of 0.75-1.12ngmL-1 and 2.50-3.75ngmL-1, respectively. Eventually, the proposed method was used for the extraction and quantification of target therapeutic peptides in plasma and urine samples, and satisfactory relative recoveries were achieved in the range of 90.6-110.3%.

Acoustic Performance Evaluation of Sugarcane Bagasse Using Ambient Sound Meter and Scanning Electron Microscopy

Abstract: Non-stop research is afoot to replace synthetic materials with green-materials for sound absorption purposes. Employing of agricultural waste as building materials has been a successful trend throughout the years. This research targets to utilize sugarcane bagasse (SB) fibers as sound barriers with sodium silicate as an adhesive. The SB fibers were treated in an alkaline solution for delignification and to improve the surface morphology. The SB fibers were casted into sheet and further tested for sound transmission loss. Experimentation revealed that the fabricated sheets can be viable option as a sound absorbing medium. A tubular porous structure was observed through Field Emission Scanning Microscope (FESEM). It has the capability to be used as a low-cost, biodegradable, and eco-friendly acoustic material as compared to glass wool and other synthetic acoustic materials. Keywords: Acoustic material, Alkali-treatment, Ambience, FESEM microscopy, Low-cost, Natural fiber, Performance, Sugarcane Bagasse, Sustainability

ZnO-CdO nanocomposites incorporated with graphene oxide nanosheets for efficient photocatalytic degradation of bisphenol A, thymol blue and ciprofloxacin

The widespread existence of different organic contaminants mostly phenolic compounds, organic dyes and antibiotics in water bodies initiated by the various industrial wastes that raised great scientific concern and public awareness as well recently owing to their prospective capability to spread these contaminants resistant gene and pose hazard to human. In the present study, a series of nanostructured ZnO-CdO incorporated with reduced graphene oxide (ZCG nanocomposites) were successfully synthesized by a simple refluxing method and characterized by using the X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, photoluminescence spectroscopy, field emission-scanning microscope (FE-SEM) and UV–visible diffused reflectance spectroscopy (DRS) for the photocatalytic degradation of bisphenol A (BPA), thymol blue (ThB) and ciprofloxacin (CFn) with illumination of UV light. The maximum degradation and mineralization of BPA, ThB and CFn was achieved around 98.5%, 98.38% and 99.28% over the ZCG-5 nanocomposite photocatalyst after UV light irradiation for 180 min, 120 min and 75 min, respectively. The superior photocatalytic activity of ZCG-5 ascribed to enhance adsorption capacity, effective separation of charge carriers consequential for the production of more ROS after incorporation of RGO nanosheets with ZnO-CdO in photocatalyst. The conceivable photocatalytic degradation mechanism of BPA, ThB and CFn was elucidated through ROS identification and the assessment of photocatalyst stability by reusability, EEO (kwh/m3order) and UV light dose (mJ/cm2) were evaluated. The plausible photocatalytic degradation pathways were proposed for the degradation of BPA, ThB and CFn via GC-MS analysis. The present work investigates the efficient removal of BPA, ThB and CFn using ZCG nanocomposites as photocatalyst.

Improvement in fracture toughness and impact resistance of E-glass/epoxy composites using layers composed of hollow poly(ethylene terephthalate) fibers

Incorporation of hollow fibers in polymer base composites has gained great interest due to their flexibility and lightweight structure. Among many research studies on this subject, the mechanical performance of polyester hollow fiber/E-glass reinforced polymer composites has not been investigated. The main objective of the present work was to investigate the fracture toughness and impact resistance of E-glass/epoxy composites hybridized by a separate layer of polyethylene terephthalate hollow fibers (PETHFs). The samples were prepared by placing a layer of PETHFs in different contents (0, 0.23, 1.18, or 2 wt.%) and in two different forms of filaments (PETHF-FIs) or staple fibers (PETHF-STs) between two layers of biaxial or triaxial E-glass fabrics. The mechanical behaviors of the samples were investigated by performing a set of tensile and impact tests. Scanning Electron Microscopy (SEM) and Field Emission Scanning Microscopy (FESEM) were also used to evaluate the surface morphologies of the hollow fibers and the fractured samples. The results revealed that, unlike PETHF-FIs, PETHF-STs could weaken the mechanical performance of the pristine E-glass/epoxy composites. The internal channel blockage of PETHF-STs was observed in the FESEM images of the fractured PETHF-STs hybrid samples. The highest toughening effects were observed with incorporation of 1.18 wt.% PETHF-FIs in biaxial E-glass/Epoxy composites and 2 wt.% PETHF-FIs in triaxial E-glass/Epoxy composites. The highest value of impact resistance belonged to the samples hybridized with 2 wt.% of PETHF-FIs. Crack deflection, fiber pull out, and fiber stretching were the predominant fracture mechanisms observed in the PETHF-FIs hybrid composites.

Size‐Controlled Facile Synthesis of Silver Nanoparticles by Chemical Reduction Method and Analysis of Their Antibacterial Performance

AbstractThis article aimed at the size‐controlled one‐pot facile synthesis of silver nanoparticles (AgNPs) by chemical reduction method and their antibacterial response against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. AgNPs coated with and without trisodium citrate (TSC) were synthesized using silver nitrate as a precursor and hydrazine as a reducing agent. Spherical AgNPs (average size 35 nm) formation, capping agents attachment, and product purity was confirmed by ultraviolet‐visible (UV–vis) spectroscopy, X‐ray diffraction (XRD), field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), the thermogravimetric analysis (TGA), and energy‐dispersive X‐ray (EDX) spectroscopy. Exposing the synthesized TSC uncoated and coated AgNPs to Gram‐negative E. coli bacteria at a concentration of 50 mg L−1, the zone inhibition was found to be 5 mm and 6 mm, respectively. Again, TSC coated AgNPs exhibited a notable zone inhibition of 8 mm to Gram‐positive S. aureus. These results suggest that chemically synthesized TSC coated AgNPs could be used as an antibiotic against S. aureus and E. coli, which is very inspiring.