SEM Micrographs Research Articles

Novel algae-mediated biosynthesis approach of chitosan nanoparticles using Ulva fasciata extract, process optimization, characterization and their flocculation performance

Chitosan nanoparticles (CNPs) are promising biopolymeric nanoparticles with excellent physicochemical, antimicrobial, and biological properties. In this investigation, CNPs were produced using Ulva fasciata biomass extract as a reducing agent. The SEM micrograph revealed that the biosynthesized CNPs appeared to be spheres with a mean size of 32.49 nm. The ζ-potential pattern of CNPs has a single peak at +33.1 mV, indicating a positively charged surface. The X-ray diffraction pattern of the biosynthesized CNPs exhibited three different peaks at 2θ = 25.24, 52.96, and 72.28°. The FTIR analysis identifies various functional groups. The thermogravimetric analyses demonstrate that CNPs have high thermal stability. Additionally, the highest biosynthesis of CNPs (8.96 mg CNPs/mL) was obtained via FCCD when the initial pH level was 4, Ulva fasciata extract concentration was 45 %, v/v, and chitosan concentration was 0.9 %. Algae-mediated synthesized CNPs were used as coagulating/flocculating agents. By using the jar test, CNPs exhibited superior flocculation performance compared to commercial coagulants like alum, FeCl3, and chitosan in bulk form. Further, different parameters were screened, and the maximum flocculating activity (FA) recorded was 83.58 ± 0.47 % at 500 mg/L of CNPs, 1–5 % clay suspension at pH and temperature ranges of 6–8 and 10–80 °C, respectively. CNPs displayed eminent performance in water clarification.

Impact of chromium substitution on structural, spectroscopic, and dielectric properties of Ba4Ni2Fe36O60 ceramics

Cr-substituted Ni2U hexaferrite series (Ba4Ni2Fe36-xCrxO60for x = 0.0 to x = 2.0 with a step size of 0.5) was prepared via sol-gel auto-combustion route and annealed at 1200 °C for 6 h. The samples were investigated using XRD, FTIR, SEM, XPS, and high frequency (1 MHz–6 GHz) dielectric and microwave absorption measurements (VNA). XRD studies revealed that Cr3+ ions successfully substituted in BaNi2U-type hexaferrite and have a single-phase structure. The average crystallite size decreased while the percentage of porosity increased with the substitution. FTIR spectra confirmed the formation of the hexaferrite phase in all compositions. SEM micrographs revealed that the prepared samples are hexagonal. XPS spectra show the presence of all constituent elements in the samples. The dielectric constant, dielectric loss, and A.C. conductivity of samples was analyzed. Cole-Cole plots with single semicircles of different radii show the grain and grain boundaries affecting the conduction process. Moreover, Cr-substitution enhanced the microwave absorption capability. The hexaferrite sample Ba4Ni2Fe35 Cr1.0O60, with a pellet thickness of 1.81 mm, showed the highest M.W. absorption at 1.09 GHz frequency with a reflection loss (R.L.) value of −55 dB. The hexagonal-shaped morphology, high porosity, and enhanced reflection loss value suggest their use in high-frequency microwave applications.

“Sunlight-Driven Catalytic Degradation of MB Dye and Multi-Cycle Re-usability Analysis of Cu2-xSe Nanoparticles”

One of the best ways to remove organic dyes based contaminant from water resources and industrial waste water is the sunlight driven photo-catalytic degradation method. The theme of the present investigation is the photocatalytic degradation of methylene blue (MB) dye using economically produced Cu2-XSe nanoparticles (NPs) catalyst under solar radiations. The Cu2-XSe NPs crystallized in the cubic structural phase with an average crystallite size around 19 nm. The direct band gap was found to be 2.1 eV. The PL spectra and corresponding CIE diagram show the Cu2-xSe NPs emitted yellow color. The SEM micrographs show that the small grains staked over others to form large grains or patches. The FTIR and EDX spectra confirmed the formation of Cu2-XSe NPs. The obtained optimum photocatalytic degradation efficiency for Cu2-XSe NPs is 90.3%. for first cycle analysis. The pseudo-first order and second order models were used to analyze the kinetic data of Cu2-XSe NPs for varying concentrations. The multiple-cycle degradation analysis by catalyst of MB dye in one day spam for continuous four cycles were also analysed and discussed. The sun light driven multi-cycle catalytic degradation confirms the re-usability of Cu2-xSe NPs for the treatment of industrial waste water and other contaminated water bodies for the survival of aquatic life and for saving environment.

Diffusion mechanisms and corrosion resistance of nanostructured ZrN-Cu coating obtained by hybrid HiPIMS-DCMS

Globalisation has brought numerous benefits regarding the cost-effective transportation of goods. Still, the shipping industry faces challenges such as corrosion, biofouling, and restrictions on heavy pollutant products used in paintings. This study proposes a solution using a multifunctional coating based on zirconium nitride and copper nano-structured coating, applying high-power impulse and direct current magnetron sputtering processes (i.e., HiPIMS and DCMS, respectively). The coating’s morphological, structural, and chemical features were analysed using advanced characterisation techniques (SEM, EDX, STEM, SAED and EELS). Potentiodynamic polarisation (PP) and Electrochemical Impedance Spectroscopy (EIS − up to 30 days) were employed to study the corrosion resistance in saline solution (3.5 wt% NaCl). Besides, activated ZrN-Cu exhibited a corrosion rate decrease from ∼ 354 x 10−4 to 52 x 10−4 mm/yr when compared to its inactivated counterpart. Besides, a ∼ 3.5-fold impedance increasing was exhibited by activated ZrN-Cu after 30 days of exposure to saline solution, meaning an increase in corrosion resistance compared to the non-activated ZrN-Cu. SEM micrographs revealed that the copper diffusion in ZrN-Cu can be provoked by a strong oxidising agent (NaOCl) or by an electrical potential. Based on the chartered evidence, a diffusion mechanism is proposed for the biocidal release (Cu) in the obtained ZrN-Cu films. The present study depicts a solution that offers a controlled biocide release and corrosion resistance, opening the possibility of its application in the maritime industry.

Fabrication, microstructure and hemostatic activity of Cu-Zn manganite nanoparticles

Copper subbed zinc manganite Zn(1-x)CuxMn2O4 (x = 0.05,0.15,0.25,0.35,0.45,0.55) (BCZMO) NPs were prepared by sol–gel co-precipitation technique at surrounding temperature. BCZMO NPs were analyzed by XRD, SEMfor microstructure characterizations. XRD study confirms the tetragon structure of BCZMO NPs and effect of copper on ZMO NPs. SEM micrographs supports our findings. The BCZMO NPs interfered in blood coagulation and exhibited pro-coagulant property. BCZMO NPs decreased the coagulation time of citrated plasma from control 4.31 min to 1.35 min. In addition, the BCZMO NPs aggregated platelets up to 80 % at a concentration of 600 µg while the agonist epinephrine prompted platelet collection of around 90 % at 10 mM concentration.No kind of hemolytic activity in RBC cells shown by these BCZMO-NPs insisting their non-toxic nature. These BCZMO-NPs exhibited pro-coagulant effect with their interference in blood coagulation cascade and initiation in platelet aggregation. Thus, BCZMO NPs can be a potential candidate in biomedical field as hemostatic agents.

Facile synthesis of cerium and vanadium doped nickel oxide nanoparticles for the enhancement of optical, electrical and thermoelectric properties

To investigate the optical, electrical and thermoelectric properties of pristine, cerium and vanadium doped NiO-NPs was synthesized by using sol-gel method. The XRD was used to investigate the FCC cubic crystal structure and crystallite size decreased from 75 to 43 nm. However, SEM micrographs depicted irregular surface morphology changed into small agglomerated grains by vanadium doped NiO-NPs. After that the EDAX analysis was performed to obtain the elemental composition (Ni, O, Ce and V) and also identified the weight percent of each element in all samples. The different functional groups such as Ni-O, OH, C-O, CO2, C=C and V-O was examined by FTIR spectra. The absorbance peak of pristine and doped NiO NPs indicate the blue shift and band gap decreased from 3.52 to 3.30 eV was calculated by UV-VIS analysis. The electrical properties were examined with two probe method and draw the relation between resistivity and conductivity. It was observed that the resistivity decreased (6 × 103 to 2 × 103 ohm-cm) with Ce and V doped NiO-NPs and conductivity increased (2 × 10-5 to 6 × 10-3 S/cm). Further, seebeck coefficient was calculated with the help of thermoelectric analysis and it was observed that seebeck coefficient increased by increasing temperature upto significant level. Overall analyses shows that vanadium doped NiO-NPs are excellent candidate for optical, electrical and thermoelectric measurements. While as prepared cerium and vanadium doped NiO-NPs will be helpful of electrical and thermoelectric devices.

Effect of ZrB2 and ZrC and mixing method on Mechanical properties and wear behaviour of Al7075 based composites for aircraft aerofoil surfaces

Developing lightweight materials with notable properties for aerospace applications is a great challenge. The impact of ZrB2 and ZrC reinforcement on the mechanical and wear behaviour of stir-cast Al7075-ZrB2-ZrC composites is investigated with a weight percentage of 2, 4, 6 and 8% ZrB2, and fixed 2% ZrC. The results showed notable improvements with a hardness of 96 HRB, tensile strength of 423MPa and compressive strength of 385MPa; hardness increased by 14%, tensile strength increased by 11% and compressive strength was enhanced by 13% when compared with pure Al7075. The wear behaviour has been analysed by pin-on-disc wear test at room temperature with loads of 10N and 20N against the sliding distance of 400m to 1200m; the wear resistance is improved by 17% and CoF is reduced by 11% compared to pure Al7075. SEM micrographs display the wear mechanism and microstructural changes happened during the wear test. Al7075-ZrB2-ZrC composites are the optimum replacement for aerofoil surfaces because of their remarkable properties.

Insights on pH-dependent Physicochemical Properties and Supercapacitance Ability of α-MoO3

The transition towards supercapacitors for efficient energy storage provides a dynamic outcome for the global warming. The MoO3 samples were prepared at various pH using facile wet-chemical approach. The orthorhombic phase (α-MoO3) was confirmed from structural investigations namely XRD, and Raman. It is also evident that the prepared samples show layered structure of MoO3, which contributed in improving the efficiency of the supercapacitor application. The morphological analysis from SEM micrographs showed a slight agglomeration. The CV studies revealed that the sample prepared at pH-10 displayed a higher specific capacitance.

Influence of Wrinkle Structure on Properties of Na-doped ZnO Films

Un-doped ZnO and Na-doped ZnO (NZO) thin films with various Na doping concentrations were successfully fabricated on glass substrates by a sol-gel process. The effect of Na ions at concentrations of 0, 1, 2, 3, 4, and 5% on the crystalline structure, surface morphology, and optoelectronic properties of ZnO films was studied using appropriate measurement techniques. XRD analysis revealed a polycrystalline hexagonal wurtzite structure in the NZO films. The NZO films' average crystal size ranged from 17.7 nm to 19.6 nm. SEM micrographs showed that wrinkle network appeared in the pure and doped ZnO films due to solvent evaporation during the thermal annealing process. UV-Vis spectroscopy pointed out that the average transmittance of NZO films is as large as ca. 78%. The optical bandgap of the films varied slightly between 3.235 eV for the pure ZnO and 3.246 eV for the Na 5% doped NZO film. When Na ions were doped into the NZO films, the electrical conductivity improved. Moreover, the absorption figure of merit exhibited the largest value of 0.981 Ω-1cm-1 for the fabricated NZO films, which enables the use of these films for solar cells and for other optoelectronic applications.

Fortification of cotton fabrics with dithiocarbamate-metal complexes to prepare durable antimicrobial fabrics

In this study, a simple and practical method is reported to fortify cotton fabrics with dithiocarbamate (DTC-Ct), dithiocarbamate-Cu (Cu-Ct) and dithiocarbamate-Ni (Ni-Ct) complexes via impregnation process to prepare durable antimicrobial fabrics. FTIR analysis indicates the presence of characteristic peaks corresponding to cellulose functional groups in the fortified fabrics. SEM micrographs illustrate the transition from a closed-packed, smooth surface in untreated cotton to a rough texture enveloped with metal complexes in fortified fabrics. EDX images confirm successful impregnation, with prominent peaks due to C and O in the untreated cotton, while additional signals of S, Cu, and Ni were observed in the fortified samples. TEM images revealed irregular, spherical nanoparticles within fortified cotton, compared with the rough surface of untreated fabrics. The average size of the treated cotton fabric fell within the range of 2.20–7.32, 3.83–28.50, and 2.70–7.32 nm for DTC-Ct, Cu-Ct and Ni-Ct, respectively. Untreated cotton fabric exhibits no inherent antibacterial properties, whereas fortified cotton fabrics demonstrate enhanced antibacterial efficacy against strains including Salmonella typhi, Enterobacter aerogenes, Shigella dysenteriae, and Klebsiella pneumonia, with Ni-Ct-fortified cotton proving most effective. Furthermore, the durability of additive adhesion to cotton fabrics was evaluated through washing tests, revealing robust adherence even after multiple cycles, with sustained antimicrobial inhibition observed for up to five wash cycles.

Deuterium plasma induced preferential erosion in ultra-high temperature ceramics TiB2 and ZrB2*

Abstract Steady-state deuterium plasma exposures were performed on ultra-high temperature ceramics titanium diboride (TiB2) and zirconium diboride (ZrB2) using the PISCES-RF linear plasma device (LPD) as early screening for first wall, plasma-facing applications. Deuterium plasma exposures were performed using 40 eV ion energies at 240, 525, and 800 °C sample temperatures and 90 eV ion energies at 240 °C sample temperatures to analyze TiB2 and ZrB2 surface morphology and chemistry evolution behavior. Post-plasma exposure chemistry characterization of the near surface ( < 50 nm) region of the samples all show transition metal enrichment, indicating boron preferential erosion. Transition metal to boron fractions vary with plasma exposure temperature under the 40 eV ion energy; metal enrichment is maximized at 800 °C and then minimized at 525 °C. SEM micrographs of all plasma exposed sample surfaces show no significant or noticeable plasma induced damage from cracking or blistering.

Novel CoFe2O4 / LaAlO3 nanocomposites: An impressive photocatalyst with p-n hetero-junction for improved H2 generation under visible exposure

The present work is devoted to the synthesis of perovskite LaAlO3 by Sol-Gel approach and its application for the photo-evolution of H2 in conjunction with cobalt ferrite CoFe2O4 prepared by nitrate route. The thermal analysis (TG/DSC) showed that the formation is completed at 600 °C. The X-ray diffraction (XRD) pattern is characteristic of a single phase, crystallizing in a rhombohedral symmetry with a crystallite size of 36 nm. The SEM micrographs revealed a homogeneous structure with an agglomeration of shaped grains (40–80 nm). The forbidden band (3.39 eV), calculated from diffuse reflectance data, is assigned to the ligand charge transfer O2−: 2p → Al3+: 3s orbital. As prepared, LaAlO3 is an n-type semiconductor as demonstrated from the capacitance - potential (C−2 - E) graph with an electron density of 9.4 × 1014 cm−3 due to oxygen under-stoichiometry. Attention was directed to photo-electrochemistry in connection with water reduction into hydrogen. With a negative conduction band potential (−0.11 VSCE), H2 generation can be synergized over the hetero-system by visible light. The photocatalytic capability of CoFe2O4 25%/LaAlO3 revealed a high H2 generation of 963 μmol g−1 in the alkaline electrolyte (NaOH, 0.1 M) with a catalyst dose of 1 mg mL−1, which is 1.3 times more than CoFe2O4 under similar conditions. Photoactivity is significantly improved by 60%, up to 2400 μmol g−1 in the presence of oxalate C2O42− as a hole scavenger in the hetero-junction, two hydrogen release tests were successfully recorded. The higher H2 production in the hetero-junction system is attributed to the lower recombination rate of electron/hole (e−/h+) in the material, due to the large band bending at the solid interfacial.

Optimizing the energy values of solid biofuel through acidic pre-treatment: An evolutionary-based neuro-fuzzy modelling and feature importance analysis

The increasing focus on sustainable energy solutions and eco-friendly fuel alternatives has sparked interest in exploring methods to enhance the energy content of solid biofuels through pre-treatment processes. This study investigates the impact of acidic (H2SO4) pretreatment on the energy content of solid biofuel derived from watermelon peel waste using machine learning methods. The biofuel properties, and calorific value (CV) were determined experimentally for both H2SO4-treated and untreated biofuel samples. Subsequently, an Adaptive neuro-fuzzy inference system (ANFIS) model with Genetic Algorithm (GA) and Grid Partitioning (GP) clustering techniques was developed to predict heating value of the biofuel, with performance evaluation based on root mean square error (RMSE), mean absolute percentage error (MAPE), mean absolute deviation (MAD), Mean Absolute Error (MAE) and R2-values. The decision tree regressor was employed to evaluate the feature importance, predictive power and impact of each input variable on CV prediction based on Gini importance metrics. To establish its superior performance, the hybrid ANFIS-GA-GP model was compared with ordinary-ANFIS and ANN model using same metrics. Results show that acid-pretreatment increased the CV of the solid biofuel by 3.53 MJ/kg (31.83 % improvement) and reduced ash content by 1.77 %. FTIR analysis revealed surface modifications, and a shift in the C-O vibrational stretch, while SEM micrographs displayed denser surfaces and reduced porosity as indicated by a lesser fiber diameter in treated samples. The GP-clustered ANFIS-GA model with a triangular membership function (tri-MF) exhibited superior performance and higher accuracy (RMSE of 0.1309, MAPE of 9.343, MAD of 0.1036, MAE of 0.1110, and R2-value of 0.9773 at model training). Furthermore, a tree decision regressor identified Fixed carbon as the most significant predictor for CV with a Gini importance of 0.988375. This study demonstrates the substantial enhancement in the energy content of biofuel using acidic pre-treatment and insights into a cutting-edge approach of improving the combustion properties of solid biofuel with machine learning models. This significantly contributes to the field of sustainable bioenergy research.

Microstructural investigation and performance of LC3 cementitious materials

Limestone calcined clay cement (LC3) is identified as an auspicious solution to the exhaustion of natural resources intended for use as construction materials. This is seen as a means of reducing both the carbon dioxide emissions and the environmental effects of energy-intensive cement manufacture. Three novel types of LC3 cements and mortar varieties were synthesized, characterized, and their potential use was assessed. Microstructural investigations were performed using experimental techniques such as XRD, XRF, FTIR, SEM, setting time, and thermal analysis. Physical and mechanical properties were also evaluated at 2, 7, and 28 d. The results showed that hydrated phases alongside the original ones were encountered. SEM micrographs exhibited some features belonging to the already detected phases. The mechanical strength of the manufactured LC3 samples (up to 35 MPa) was quite promising compared to that of commercial cements. From the above, it could be stated that the used materials might be a good substitute for clinker in the manufacture of LC3 cements. LC3-50 and LC3-52 may both be used in favor of CPJ35 and CPJ45, respectively.

Preparation and characterizations of metal-based complexes derived from the reaction of trizma base with Mg(II), Ca(II), and Ba(II) ions

Trizma base is a small organic compound that possesses one amino group (-NH2) and three hydroxyl groups (-OH). Three products of trizma base as a ligand were prepared from the reaction of Mg(II), Ca(II), and Ba(II) ions with the ligand at a temperature of 65 °C and stoichiometry of 1:1 (ligand to metal ion). The trizma ligand was referred to as Tris, and its complexes with Mg(II), Ca(II), and Ba(II) ions were referred to as Product 1, Product 2, and Product 3, respectively. After the preparation of the products, they were characterized by several analytical methods, including spectroscopies [Fourier-transform infrared (FT-IR) and ultraviolet/visible (UV-visible)], thermogravimetry (TG), elemental analyses, X-ray diffraction (XRD), and scanning electron microscope with environmental mode (ESEM). Analytical results suggested that Tris ligand captured the investigated metal ions using the amino group (-NH2) and one hydroxyl group (-OH) forming complexes with general composition of [MgTris(H2O)4]·Cl2·2H2O (Product 1), [CaTris(H2O)4]·Cl2·2H2O (Product 2), [BaTris(H2O)4]·Cl2·H2O (Product 3). The corresponding gross formulas for these products were C4H23NO9MgCl2 (324.34), C4H23NO9CaCl2 (340.11), and C4H21NO8BaCl2 (419.37 g/mol), respectively. SEM micrographs captured at high levels of magnification (×100,000) clearly illustrate variations in the morphology of products 1, 2, and 3. KEY WORDS: Trizma base, Spectral analysis, Thermogravimetry, SEM micrographs Bull. Chem. Soc. Ethiop. 2024, 38(6), 1791-1801. DOI: https://dx.doi.org/10.4314/bcse.v38i6.22

Polaron assisted hopping mechanism in microwave processed Nd doped second layered aurivillius SrBi2Nb2O9 ceramics

The polycrystalline Sr0.8Sn0.2Bi1.75Nd0.25Nb2O9 (NdSBN) was synthesized using the green synthesis microwave sintering method, which significantly reduced the processing parameters of the NdSBN ceramics. Orthorhombic crystal structure with A21am symmetry was revealed by Rietveld refinement study, whereas the doping-induced strain and crystallite size was studied using the Williamson Hall method. Crossectional SEM micrographs confirm the plate-like structure, with an average grain size of 273.7 nm. A diffuse type of phase transition was observed at 345 °C, which usually arises due to compositional fluctuations and mobile oxygen vacancies; further, the diffusiveness of the NdSBN was studied using Uchino and Nomura function, a modified version of Curie-Weiss law (CW). The frequency and temperature-dependent dielectric study of NdSBN ceramics display a Maxwell-Wagner relaxation with a high loss in a low frequency regime, possibly due to the presence of leakage current in the solid solution. Frequency dependent AC conductivity obeys Jonscher's power law, whereas DC conductivity supports polaron assisted hopping in NdSBN composition with dual activation energies of 0.55 eV and 0.75 eV, which correspond to electrons and ions, respectively. The non-Debye type relaxation mechanism in conjunction with negative temperature coefficient of resistance (NTCR) behavior was demonstrated by temperature dependent impedance spectroscopy, while modulus spectroscopy confirmed the multiple relaxation processes in NdSBN ceramics.

Synthesis and characterization of fluorescent carbon dots obtained from citrus x sinensis by an eco-friendly method

The synthesis and characterization of fluorescent carbon dots (CDs) obtained by an environmentally friendly method through carbonization, fragmentation and centrifugation of orange peel (citrus x sinensis) are reported. By thermogravimetry, 4 degradation regions associated with hemicellulose, lignin and organic matter were found. The SEM micrograph shows a rough surface morphology with flakes and granulation due to the carbonization process. X-ray diffraction (XRD) shows a hexagonal crystalline structure associated with graphitic carbon, which was confirmed by Raman scatterings, Raman spectroscopy that presented two main vibrational bands, D and G, associated with active defects in the graphitic carbon crystalline structure. The Transmission electron microscopy (TEM) micrograph showed CDs of size 33.65 ± 0.68n, and with High-Resolution TEM (HRTEM) an interplanar distance of 0.213 nm in the direction of the crystal planes (100) of graphitic carbon was obtained, which were confirmed by XRD and Raman spectroscopy. X-ray photoelectron spectroscopy revealed the relative atomic composition and identified the strongest photoelectron transitions of carbon, sp2 (286 eV) and sp3 (285 eV), in graphitic carbon. Ultraviolet–visible (UV–Vis) spectroscopy of the CDs obtained from fragmentation graphitic carbon showed a band at 205 nm associated with CC bonds π-π* of CC and n-π*, as well as two bands at 276 and 328 nm associated with bond transitions. The Fourier Transform Infrared (FTIR) spectrum showed bands associated with CHs bonds as well as CC, CN bonds of the CDs. Fluorescence spectroscopy showed three emission bands at 2.43, 2.54 and 2.87 eV. The CDs showed the emission of the characteristic blue colour.

On-Demand Removable Chitosan Based Self-Healing and Antibacterial Hydrogel for Delivery of Tetracycline and Curcumin As Potential Wound Dressing Material.

Wound care is a flourishing branch of healthcare wherein a great amount of research is devoted to develop competent wound dressings. Safe, cost-effective, and biocompatible dressings aid in wound healing without inflicting external trauma and subsequent scar formation. Toward this, we have attempted to develop robust wound dressing material with self-healing and antibacterial properties. We have cross-linked chitosan with 4-formyl phenylboronic acid (4-FPBA) and in situ generated dehydroascorbic acid (DHA) utilizing the dynamic imine and boronate ester linkages. Displaying a channeled microstructure in the SEM micrographs, the hydrogel exhibits a massive water uptake capacity of ∼900% at acidic pH. The hydrogel could completely self-heal within 3 min, and the results are further supported by rheological analysis. By virtue of positive surface charge, it shows a promising tissue adhesive property. Moreover, it affords clean and compliant removal from the wound surface via dissolution induced by dopamine to potentially reduce secondary scarring from peeling of wound dressings. The dressing could significantly act against skin infections caused by S. aureus bacteria with enhanced antimicrobial efficiency via loading of antibiotic drug, tetracycline hydrochloride. A sustained release of tetracycline and Curcumin was observed, which demonstrated the release ability for hydrophilic and hydrophobic bioactive agents. In-vitro studies revealed 93% cell viability with a hemolytic ratio as low as 2.5%, thereby presenting a good self-healing and biocompatible material for wound healing.

Study of phase evolution, mechanical, and tribological behaviour of a novel β-phase strengthened Ti-alloy with Fe and Co alloying via a laser material deposition route

A new Ti64-Fe-Co alloy was studied via a laser-material-deposition method. Associated with high growth restriction factors, β-eutectoid (Fe, Co) alloying minimizes anisotropy (due to the prior columnar β-grain growth) in the laseradditive -manufacturing (AM) built Ti-parts along with enhanced properties. Fe alloying for Ti64 via laser-AM results in superior strengthening with reduced ductility, where a good combination of strength and elongation properties can be achieved for a Ti-Fe-Co system. However, studies on Ti-Fe-Co-based systems via laser processing are limited. Co possesses a similar electronic property as Fe and the Ti-Fe system accompanies further solute addition. The effect of Co alloying the Ti64-Fe system was investigated in this study via a pre-placed laser-material-deposition method. A Ti64–5Fe-5Co alloy was formulated referring to CALPHAD simulations, along with a Ti64–10Fe composition. The new Ti-alloys were fabricated via both the laser-material-deposition and conventional vacuum arc melting routes, and the characteristics of the fabricated samples were examined. XRD analysis shows the evolution of the β-Ti phase with Fe and Co alloying, which agrees with the thermodynamic phase simulation results. The corresponding SEM micrographs depicted a β-phase dominant matrix with α-dendrites, and the solidification path was discussed. Considerable grain refinement was obtained for the laser-deposited alloys compared to the arc-melted ones, with an improved hardness value twice that of the commercial Ti64. A reduced stiffness for the laser-deposited Ti64–5Fe-5Co was observed from the load-vs-displacement characteristics, indicating matrix softening with Co alloying, which might benefit the elongation properties. The studied Ti-alloy shows a 30 % improvement in the dry-sliding wear characteristic with reduced fretting and abrasion compared to the commercial Ti64. The studied Ti-alloys were located in the theoretical d-electron space and new (Bo) ̅-(Md) ̅ vectors were introduced. Further studies on this would help in extending the applicability of laser-AM-built Ti-components.

Poly(Vinyl Alcohol)/Poly(Acrylic Acid) Gel Polymer Electrolyte Modified with Multi-Walled Carbon Nanotubes and SiO2 Nanospheres to Increase Rechargeability of Zn-Air Batteries.

Zn-air batteries (ZABs) are a promising technology; however, their commercialization is limited by challenges, including those occurring in the electrolyte, and thus, gel polymer electrolytes (GPEs) and hydrogels have emerged as substitutes for traditional aqueous electrolytes. In this work, PVA/PAA membranes were synthesized by the solvent casting method and soaked in 6 M KOH to act as GPEs. The thickness of the membrane was modified (50, 100, and 150 μm), and after determining the best thickness, the membrane was modified with synthesized SiO2 nanospheres and multi-walled carbon nanotubes (CNTs). SEM micrographs revealed that the CNTs displayed lengths of tens of micrometers, having a narrow diameter (95 ± 7 nm). In addition, SEM revealed that the SiO2 nanospheres had homogeneous shapes with sizes of 110 ± 10 nm. Physicochemical experiments revealed that SiO2 incorporation at 5 wt.% increased the water uptake of the PVA/PAA membrane from 465% to 525% and the ionic conductivity to 170 mS cm-1. The further addition of 0.5 wt.% CNTs did not impact the water uptake but it promoted a porous structure, increasing the power density and the stability, showing three-times-higher rechargeability than the ZAB operated with the PVA/PAA GPE.