Materials Plus

Investigation of Structural, Dielectric, Magnetic and Impedance Spectroscopy of MgO/CuFe2O4 Nanocomposites

Asif Ilyas, Kashif Ali — Tue, 26 Mar 2024 00:00:00 +0800

This study investigates the properties of (MgO)_x/(CuFe₂O₄)_1-x x= 10–50 wt.% nanocomposites (NCPs) prepared by physical mixing of both materials. The crystal structure, phase identification and morphology were analyzed by x-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The investigation revealed the formation of required phases which are in nanometer dimension (22–54 nm) computed by Debye-Sherrer’s formula. Both the real and imaginary parts of dielectric constant (ε^/& ε^//), a.c. conductivity (σ_ac), and impedance were measured in the frequency range of 1kHz to 2MHz by LCR meter. The ε^/ and ε^//revealed a decreasing trend with frequency, while MgO weight fractions in NCPs enhance the permittivity values. The real and imaginary parts of impedance (Z^/& Z^//) demonstrate a decreasing trend with frequency which is ascribed to increase in σ_ac. The complex impedance spectroscopy (CIS) analysis shows semicircular arcs at higher frequency, which are due to electrical transport properties of conducting grains. The effect of MgO contents on magnetic properties were analyzed by measuring M-H loops at room temperature through vibrating sample magnetometer (VSM). Both the saturation magnetization (M_s) and coercivity (H_c) values show a decreasing profile with MgO fractions, which are due to increase in nonmagnetic contents and decrease in surface anisotropy respectively.

Investigation of Manufacturing 316L Stainless Steel Closed Impeller Using Laser Powder Bed Fusion

Yousef Alhorr, Qusai Alkhalaf — Thu, 20 Jun 2024 00:00:00 +0800

The manufacturing of closed impellers via Laser Powder Bed Fusion technology entails inherent complexities, demanding meticulous attention to support structure design, determination of building angle, and down-skin energy density to ensure successful production. This study explores the use of stainless steel 316L in fabricating closed impellers using LPBF. The aim is to investigate the impact of process parameters and building angles on impeller fabrication quality. In addition to studying the effect of energy density on the surface roughness and hardness values of the impeller. The investigation examines building angles of 0˚, 30˚, and 90˚ for a closed impeller, revealing that a 30˚ building angle yields successful printed parts. Moreover, to achieve defect-free closed impellers, it is imperative to maintain down-skin energy density between 80% and 100% of in-skin energy density. The maximum hardness and minimum surface roughness were recorded at 233 HV and 12.79 µm, respectively, when the energy density was 41.66 J/mm³ and 55.55 J/mm³ respectively. The novelty of this study lies in the fabrication of closed impellers using stainless steel 316L through laser powder bed fusion.

Characterization of Ti-6Al-4V Bar for Aerospace Fastener Pin Axial Forging

Wed, 20 Mar 2024 00:00:00 +0800

Ti-6Al-4V warm forged fasteners are a critical part of the aerospace industry, as they are used in vast quantities for mechanical joining of components for the fuselage, wing-skin and aero-engine. These components are produced in vast quantities at rapid production rates through multi-blow axial forging However the rate that they are manufactured means that manufacturers rely upon periodic part conformance testing to understand if the part is within tolerance or if any undesirable manufacturing defects such as cracks or underfilling are present. Thus, a right-first-time manufacturing approach is essential to minimize non-conformant scrap. An analysis of the Ti-6Al-4V supplied raw material for axial forging, in a variety of different bar diameter sizes and from different industrial suppliers, was conducted. This was to attempt to understand whether material property variation or operator variation was the root cause for some material behaving differently during the manufacture route. Experimental testing was performed through microstructure characterization and mechanical testing methods. The volume fraction of the β-phase was noted to be marginally higher in material with good forgeability. The hardness of the inner core of the bar appears to be a critical material property for the Ti-6Al4V bar, with an overly hard bar-core hindering forgeability of the bar. This is believed to be due to the hotter central region malleability being key for forgeability. Micro-void porosity was also noted which could lead to stress concentration locations, or crack initiation, and as such is a deleterious property for forgeability. The experienced forgeability of the Ti-6Al-4V bars have been demonstrated to be sensitive to rather small variation in measured microstructure and mechanical property. It is believed that cumulative impacts of small differences, 1% variation in α-phase volume fraction, small variations in elongation to failure, 1% variation in elastic modulus and microhardness profile variation at the center of the bar of less than 10 HV0.3, can combine to significantly impact the forgeability of Ti-6Al-4V bar.

Development and Evaluation of an AZ31 Magnesium Alloy and Eggshell Powder Composite for Orthopedic Surgical Implants

Mon, 24 Jun 2024 00:00:00 +0800

This research investigates the development and evaluation of a novel composite material composed of AZ31 magnesium alloy and eggshell powder, designed for use in surgical bone implants. The primary objective is to enhance the mechanical properties and biocompatibility of AZ31 by incorporating eggshell powder, which is known for its hardness and strength. The composite is fabricated using the stir casting technique, where the molten magnesium is mixed with finely ground eggshell powder to achieve uniform dispersion. The resulting samples are subjected to rigorous mechanical testing, including tensile and compressive strength evaluations, as well as hardness measurements. Additionally, the internal structure and particle distribution of the composite are analyzed using scanning electron microscopy and X-ray diffraction, respectively. This study aims to provide a comprehensive understanding of the material properties and structural characteristics of the composite, with a focus on its potential applications in orthopedic load-bearing implants and fixation devices, such as bone plates, joint replacements, screws, rods, dental implants, and cardiac stents. The findings are expected to contribute to the development of improved biomaterials for medical applications, leveraging the unique benefits of both magnesium alloy and eggshell powder.

Printability, Performance and Adaptive Moisture Response: Advanced Hygromorphic materials using synergistic properties of keratin and lignin

Warren James Grigsby, Sonya Scott, Hosea Watson, Paul Middlewood — Thu, 20 Jun 2024 00:00:00 +0800

Developing materials that respond and adapt to external stimuli are of increasing interest in additive manufacturing as their potential to react to triggers can be used as a response required of a user. As biopolymers, keratin and lignin exhibit macromolecular behaviours influenced by moisture and these properties have been evaluated as four dimensional (4D) responsive hygromorphic materials. Through three dimensional (3D) paste keratin-lignin hydrogel deposition, the integrity, mechanical properties and 4D moisture sorption responses of these materials was found to be enhanced by additives including carrageenan, guar gum and calcium chloride. As an example, inclusion of carrageenan and calcium led to greater dynamic vapour moisture sorption behaviours compared to guar gum. While carrageenan acted to improve mechanical properties, combination with calcium led to lower mechanical performance and plasticization of hydrogels. In contrast, the cross-linking provided by calcium ions reduced liquid water sorption and was found to extend sample mechanical performance on water immersion. Inclusion of guar gum improved keratin-lignin hydrogel deposition, but provided minimal enhancements of material properties or moisture responses. Overall, study findings suggest selective combinations of carrageenan and calcium can produce 4D moisture responsive keratin-lignin hydrogels where these resulting adaptative swell or softening behaviours may be used in hygromorphic material applications.

Modeling of Cr3+ doped Single Crystals of Lithium Sulfate Monohydrate

Bharati, Singh, Ram Kripal Kripal — Tue, 21 May 2024 00:00:00 +0800

Crystal field parameters and zero field splitting parameters of Cr³⁺doped lithium sulphate monohydrate, Li₂SO₄.H₂O single crystals are computed with the help of superposition model. The appropriate sites for Cr³⁺ ions in Li₂SO₄.H₂O with distortion are considered for calculation. Theoretical zero field splitting parameters obtained including local distortion in the calculation correspond well with the values obtained from the experiment. The optical energy bands for Cr³⁺ in Li₂SO₄.H₂Oare evaluated with the Crystal Field Analysis Program and crystal field parameters. The results suggest that Cr³⁺ ions substitute for one of the Li⁺ ions, and the charge compensation occurs by the proton vacancies in Li₂SO₄.H₂O single crystals.

Bayesian Uncertainty Update to a Model of Flexural Strength of α-SiC

Eric A. Walker, Jason Sun, James Chen — Fri, 22 Mar 2024 00:00:00 +0800

This article demonstrates a statistical method to update the uncertainty in the flexural strength of silicon carbide, α-SiC. The previously reported uncertainty for the flexural strength of α-SiC was a constant ±15%. However, this uncertainty should be adjusted as more data becomes available. A Bayesian approach is proposed to rapidly and precisely update the uncertainty. To validate the method, five scenarios are demonstrated. The first scenario assumes the experimental data is distributed as the model predicts. The second and third scenarios have the model underestimating and overestimating flexural strength, respectively. The fourth and fifth scenarios use data from a thermo-mechanical fracture model. The thermo-mechanical fracture model introduces a change in the temperature transition of flexural strength. The uncertainty decreased from 15% to a range between 8.3% and 13.4%. Two parameters are inferred in the fourth scenario while five are inferred in the fifth scenario. Inferring five parameters leads to more consistent uncertainty across temperature.

Electrically induced and controlled piezoelectricity

Yuriy Poplavko — Mon, 24 Jun 2024 00:00:00 +0800

The quasi-linear electromechanical effect, which resembles piezoelectricity, can be induced by strong electric field in any solid dielectric. This effect is defined as linearized electrostriction, which is observed in the biasing electric field and is proportional to the square of the dielectric permittivity. The present work analyses physical mechanisms of the occurrence of such an effect in the piezoelectrics, the paraelectrics and the relaxor ferroelectrics, taking into account the inertia of electromechanical response. Hysteresis-less electromechanical control of deformation is used in actuators and tuneable microwave devices. The efficiency of the induced piezoelectricity is maximal in dielectrics with high permittivity, while the efficiency is ensured by mechanisms of low-inertia quasi-elastic polarization. To assess the maximum performance of piezoelectric actuators made of different materials, the method of dielectric spectroscopy is used.

An antibiotic efficacy comparative study between market-prescribed and solid-lipid fluoroquinolone ophthalmic nanoformulation against conjunctivitis

Rakesh P. Patel, Bijit Saha, Tripti Halder, Nitin Gupta — Sat, 11 May 2024 00:00:00 +0800

Besifloxacin hydrochloride (BSF) drug substance (DS), is effective against gram-positive and gram-negative microorganisms. BSF (liquid suspension form) is already available in two different market brands: Besivance and Besix. Both of these commercialized drug products (DP) have lower mucoadhesive characteristics, therefore they spend less time in contact with various ocular tissues (cornea and conjunctiva). This research work emphasized the design, development, and optimization of BSF-loaded solid-lipid nanoparticles (BSF@SLN) to increase antibacterial activity by enhancing drug absorption through passive diffusion techniques in the ocular organ compared to conventional dosage forms. The SLN was prepared through a very simple process hot homogenization process using glyceryl monostearate and polysorbate-80 along with poloxamer-188 and water for injection. Various characterization techniques like FTIR, DSC, and XRD were performed to check the compatibility between DS and excipients. The preliminary formulation of SLN was characterized through zeta potential, polydispersity index, and particle size techniques. The developed SLN was optimized following 3² factorial designs. Surface morphology and size of optimized BSF@SLN ophthalmic DP were confirmed by using advanced microscopic techniques such as SEM. In-vitro release of optimized BSF@SLN ophthalmic DP was performed by using two chambers of Franz diffusion cell. Stability studies of optimized BSF@SLN ophthalmic nanoformulations were tested for up to 6 months at 25°C ± 2°C/60% ± 5% RH. The antimicrobial activity of optimized ophthalmic nanoformulation was found 2.76 times more effective compared to the Besix eye drop. In-vivo study of BSF@SLN ophthalmic nanoformulations was carried out with an eye irritancy test and compared with marketed DP (Besix). and found significant pharmacological.

Unveiling Capillary-Tissue Fluid Exchange: Understanding Red Blood Cell Deformation in Constricted Vessels and its Clinical Significance

Kshiteendra Mohan Jaiswal, Mo. Sadique, Shabab Akbar, Prof. Sapna Ratan Shah — Fri, 21 Jun 2024 00:00:00 +0800

Capillary-tissue fluid exchange plays a critical role in maintaining tissue homeostasis, and understanding the behavior of red blood cells (RBCs) in narrow vessels is fundamental to elucidating this process. This paper explored the phenomenon of RBC deformation in constricted vessels and its clinical implications. This study delves into the intricate dynamics of blood flow within narrow capillaries, particularly focusing on situations where the diameter of these vessels is smaller than that of red blood cells (RBCs). In such confined spaces, the proximity between RBCs and the vessel walls is minimal, allowing plasma to permeate through. This research explored how various factors, including the shape of deformed RBCs, their velocity, and tissue permeability, influence blood flow patterns. It reveals that in scenarios where tissues exhibit lower permeability, blood flow tends to be more uniform, while faster-moving RBCs encounter less resistance. By comparing its findings with existing models, this study underscores its significance in advancing our understanding of blood flow dynamics in small vessels. Such insights hold promise for the development of novel diagnostic tools targeting a range of diseases. Additionally, this paper discussed the clinical relevance of RBC deformability in various pathological conditions, including microvascular diseases, ischemia-reperfusion injury, and inflammation. Understanding the complex interplay between RBC deformability, microvascular function, and disease pathology has significant implications for the development of novel diagnostic and therapeutic strategies targeting capillary-tissue fluid exchange.