Effect of Synthesized Titanium Dioxide Nanofibers Weight Fraction on the Tribological Characteristics of Magnesium Nanocomposites Used in Biomedical Applications

Biomedical applications, such as artificial implants, are very significant for the disabled due to their usage in orthopedics. Nevertheless, available materials in such applications have insufficient mechanical and tribological properties. The current study investigated the mechanical and tribological properties of a biomedical metallic material, magnesium (Mg), after incorporating titanium dioxide nanofibers (TiO2) with different loading fractions. The TiO2 nanofibers were synthesized using the electrospinning technique. The ball-milling technique was utilized to ensure the homogenous distribution of TiO2 nanofibers inside the Mg matrix. Then, samples of the mixed powder with different loading fractions of TiO2 nanofibers, 0, 1, 3, 5, and 10 wt.%, were fabricated using a high-frequency induction heat sintering technique. The physicomechanical and tribological properties of the produced Mg/TiO2 nanocomposites were evaluated experimentally. Results showed an enhancement in mechanical properties and wear resistance accompanied by an increase in the weight fraction of TiO2 nanofibers up to 5%. A finite element model was built to assess the load-carrying capacity of the Mg/TiO2 composite to estimate different contact stresses during the frictional process. The finite element results showed an agreement with the experimental results

Effect of Nickel Content on the Corrosion Resistance of Iron-Nickel Alloys in Concentrated Hydrochloric Acid Pickling Solutions

The effect of Ni content on the resistance against corrosion of Fe-36% Ni and Fe-45% Ni alloys in 1 M hydrochloric acid pickling solution was reported. Various electrochemical and spectroscopic techniques such as potentiodynamic cyclic polarization (CPP), open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiostatic current-time (PCT), and scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) have been employed. CPP measurements indicated that the corrosion current and corrosion rate recorded lower values for the alloy that had higher nickel content. OCP curves proved that the presence of high Ni content shifts the absolute potential to the positive potential direction. EIS results revealed that the surface and polarization resistances were much higher for the alloy with higher Ni content. PCT curves also showed that the absolute currents were lower for Fe-45% Ni alloy. All results were in good agreement with others and confirmed clearly that the corrosion resistance in HCl solutions for Fe-45% Ni alloy was higher than that obtained for Fe-45% Ni alloy

Stability analysis of the magnetized casson nanofluid propagating through an exponentially shrinking/stretching plate: Dual solutions

In this research, we intend to develop a dynamical system for the magnetohydrodynamic (MHD) flow of an electrically conducting Casson nanofluid on exponentially shrinking and stretching surfaces, in the presence of a velocity and concertation slip effect, with convective boundary conditions. There are three main objectives of this article, specifically, to discuss the heat characteristics of flow, to find multiple solutions on both surfaces, and to do stability analyses. The main equations of flow are governed by the Brownian motion, the Prandtl number, and the thermophoresis parameters, the Schmid and Biot numbers. The shooting method and three-stage Lobatto IIIa formula have been employed to solve the equations. The ranges of the dual solutions are fwc1≤fw and λc≤λ , while the no solution ranges are fwc1>fw and λc>λ . The results reveal that the temperature of the fluid increases with the extended values of the thermophoresis parameter, the Brownian motion parameter, and the Hartmann and Biot numbers, for both solutions. The presence of dual solutions depends on the suction parameter. In order to indicate that the first solution is physically relevant and stable, a stability analysis has been performed

Investigation of the Mechanical and Tribological Behavior of Epoxy-Based Hybrid Composite

The main target of this study is to evaluate the impact of hybrid reinforcement using Al2O3 nanoparticles and graphite on the epoxy nanocomposites’ mechanical and tribological properties. Various weight fractions of the reinforcement materials, ranging from 0 to 0.5 wt.%, were incorporated into the epoxy. The aim is to enhance the characteristics and durability of the polymers for potential utilization in different mechanical applications. The addition of hybrid additives consisting of Al2O3 nanoparticles and graphite to the epoxy resin had a noticeable effect on the performance of the epoxy nanocomposites. The incorporation of these additives resulted in increased elasticity, strength, toughness, ductility, and hardness as the concentration of reinforcement increased. The enhancement in the stiffness, mechanical strength, toughness and ductility reached 33.9%, 25.97%, 25.3% and 16.7%, respectively. Furthermore, the frictional tests demonstrated a notable decrease in both the coefficient of friction and wear with the rise of the additives’ weight fraction. This improvement in the structural integrity of the epoxy nanocomposites led to enhanced mechanical properties and wear resistance. The SEM was utilized to assess the surfaces of tested samples and provide insights into the wear mechanism

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Development of a Microbial Fuel Cell Using Methylococcus Chroococcus Bacteria as a Biocatalyst

Methane is an extensively accessible green energy that can be obtained organically just by way of through natural gases. However, using methane in fuel at ambient temperature conditions is quite challenging, due to its high thermodynamically stability. In this present investigation, the feasibility of using methane in the low-temperature microbial fuel-cell (MFC) with an unadulterated culture of Methylococcus chroococcus without the inclusion of any additional electron mediators is investigated. The microbial fuel cell setup was prepared using a salt bridge. Through potentiodynamic study, power density, and OCV, it can be seen that the setup delivers a sufficient amount of voltage and power as the days progress. Electrochemical Impedance Spectroscopic investigations also depict the fact that the cell required roughly one day to balance out, and kept working at full force for up to seven days. This work exhibits the chance of creating power utilizing methane as one of the main carbon sources at ambient temperature with an M. chroococcus unadulterated culture as the direct electron-transporting MFC biocatalyst

Alloying Elements Effects on Electrical Conductivity and Mechanical Properties of Newly Fabricated Al Based Alloys Produced by Conventional Casting Process

The present investigation deals with a comprehensive study on the production of aluminum based alloys with the incorporation of different alloying elements and their effect on its electrical conductivity and mechanical properties. Casting of pure aluminum with different concentration and combinations of alloying additives such as cupper (Cu), magnesium (Mg) and silver (Ag) were carried out using a graphite crucible. The as-cast microstructure was modified by hot rolling followed by different heat-treated conditions viz., annealing, normalizing, quenching, and age hardening. The mechanical properties and electrical conductivity of the produced heat-treated alloys sheets under various processing conditions were carried out using tensile testing, hardness, and electrical resistivity measurements. It was found that by increasing the alloying elements content, yield strength results increased significantly by more than 250% and 500% for the as rolled and 8 h aged Al-Cu-Mg alloy, respectively. On the other hand, the electrical conductivity reduces slightly with −14.6% and −16.57% for the as rolled and 8 h aged of the same Al-Cu-Mg alloy, respectively

Ameliorative Corrosion Resistance and Microstructure Characterization of 2205 Duplex Stainless Steel by Regulating the Parameters of Pulsed Nd:YAG Laser Beam Welding

Welding parameters can greatly affect the final product. In this study, there was a variation given on the pulse energy, i.e., heat input parameters. The microstructure was analyzed and presented in relation to the efficiency of corrosion. The microstructural study showed the changes of the fusion zone (FZ) and the heat-affected zone (HAZ) with an increase in pulse energy. The development of a prominent austenite process on the weld material had a prolonged effect on its corrosion resistance property. Electrochemical impedance spectroscopy (EIS) and potentiodynamic measurements were used to test the electrochemical activity of laser-weld 2205 duplex stainless steel in an aqueous 3.5% NaCl solution. Finally, the findings of the EIS analysis were supported by Raman spectroscopy. Based on the obtained results, the 2205 duplex stainless steel (DSS) weld obtained at a higher pulse energy showed higher corrosion resistance than the welded sample obtained at a low pulse energy. The impedance spectroscopy confirmed a smooth surface property with an increase in the pulse energy and the presence of an oxide layer, a finding also confirmed by the Raman spectroscopy measurements

Low-Cost High-Performance SnO2–Cu Electrodes for Use in Direct Ethanol Fuel Cells

The high cost of Pt-based electrode materials limits the commercialization of fuel cells and their subsequent application in renewable energy production. It is thus necessary to develop economical, high-performance electrodes alongside biofuels to reduce the pollution associated with the production of energy. Tin dioxide–copper foil (SnO2–Cu) electrode materials are herein developed using an electrodeposition process. Cyclic voltammetry, chronoamperometry, and potentiodynamic polarization methods are used to electrochemically characterize the electrode materials, with the results revealing that their excellent catalytic properties result in them delivering a high current. The surface morphologies of the developed electrodes are examined using scanning electron microscopy, with the results showing that upon an increase in the deposition time, a finer deposit of SnO2 is formed on the surface of the Cu foil. Consequently, electrochemical oxidation using an enhanced surface area of the material leads to it exhibiting a high current and excellent corrosion resistance. Powder X-ray diffraction was used to confirm the successful depositing of SnO2 on the surface of Cu. The fuel cell fabricated using the SnO2–Cu electrode is promising for use in clean energy generation, as it can be prepared at low cost compared to conventionally used electrodes