Corrosion Control of Mg-Zn Implant Alloys in Simulated Body Fluid

Magnesium alloys have recently attracted the attention as a new biodegradable material.  In this study, Mg-Zn alloys (1-4wt.% Zn) were fabricated with high purity raw materials using a clean melting process (fluxless method) and a protective atmosphere of CO2 + 0.4 SF6. The as-cast microstructures of the investigated alloys were characterized by optical and scanning electron microscopes, EDS and XRD. Corrosion properties of the prepared alloys were examined in simulated body fluid (SBF) by electrochemical techniques and immersion test (hydrogen evolution method).  Surface modification of the prepared alloys was performed using micro arc oxidation (MAO) treatment and hydroxiapatite (HA) coating. The results of the as-cast microstructure showed that Zn up to 2 wt% was completely dissolved in a-Mg matrix. On increasing Zn content (> 2wt%) the grain size decreased and a second MgZn2 phase was observed. Corrosion testing results revealed that Mg-1,2,3 wt% Zn have almost the same corrosion rates (0.025 mm/y) whereas Mg-4Zn has the highest degradation rate. Hydroxiapatite (HA) coating on micro-arc oxidation (MAO) treated magnesium alloys formed a dense and compact layer on the surface of magnesium alloys which had greatly improved surface properties and enhanced corrosion resistance of the prepared alloys. Keywords: Mg alloys, implants, biodegradable, corrosion, surface modificatio

SOWING DATE AND IRRIGATION EFFECTS ON PRODUCTIVITY AND WATER USE EFFICIENCY IN SUNFLOWER

Abiotic stresses represent a major impediment to crop productivity, especially in arid regions. Thus, over two years of 2014 and 2015, a field experiment was undertaken at El Nubaria region, Egypt to assess the productivity and water use efficiency (WUE) of sunflower as affected by planting dates (April 21, May 21, and June 21) and  irrigation levels (ET100%, ET85% and ET70%,). Results clarified that leaf chlorophyll a content was higher by sowing in May than in either April or June sowings, while leaf carotenoides of plant sown in May or June surpassed those sown in April. The minimal value of proline was obtained with sowing in May. Sowing in May increased plant height by 52.2 and 22.3 as well as LAI by 19.3 and 73.1% than sowing in April and June, respectively. The reductions in seed yield, oil yield and WUE amounted to 10.5 and 12.8, 13.7 and 18.3 as well as 11.8 and 9.8 % with April and June sowings, respectively, compared to May sowing. ET100% showed superiority over than ET85% and ET70% in improving sunflower yields and its attributes, but WUE did not affect. Sunflower sown in May and irrigated with ET100% gave the maximum values of seed yield and its attributes and WUE surpassing other interaction treatments. In June, WUE value increased under severe water deficit i.e. ET70% comparing to moderately water–stressed (ET85%) or well–watered conditions (ET100%)

Application of a Novel Synergetic Control for Optimal Power Extraction of a Small-Scale Wind Generation System with Variable Loads and Wind Speeds

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).The synergetic control technique (SCT) has the solution for understanding the symmetry inherent in the non-linear properties of wind turbines (WTs); therefore, they achieve excellent performance and enhance the operation of the WT. Small-scale WTs are efficient and cost-effective; they are usually installed close to where the generated electricity is used. This technology is gaining popularity worldwide for off-grid electricity generation, such as in rural homes, farms, small factories, and commercial properties. To enhance the efficiency of the WT, it is vital to operate the WT at its maximum power. This work proposes an efficient and fast maximum power point tracking (MPPT) technique based on the SCT to eradicate the drawbacks of the conventional methods and enhance the operation of the WT at the MPP regardless of wind speed and load changes. The SCT has advantages, such as robustness, simplified design, fast response, no requirement for knowledge of WT characteristics, no need for wind sensors or intricate power electronics, and straightforward implementation. Furthermore, it improves speed convergence with minimal steady-state oscillations at the MPP. The investigated configuration involves a wind-driven permanent magnet synchronous generator (PMSG), uncontrolled rectifier, boost converter, and variable load. The two converters are used to integrate the PMSG with the load. Three scenarios (step changes in wind speed, stochastic changes in wind speed, and variable electrical load) are studied to assess the SCT. The results prove a high performance of the suggested MPPT control method for a fast convergence speed, boosted WT efficacy, low oscillation levels, and applicability under a variety of environmental situations. This work used the MATLAB/Simulink program and was then implemented on a dSPACE 1104 control board to assess the efficacy of the SCT. Furthermore, experimental validation on a 1 kW Darrieus-type WT driving a PMSG was performed.Peer reviewe

Risk factors for traumatic and non-traumatic lower limb pain among preadolescents: a population-based study of Finnish schoolchildren

BACKGROUND: The child's lower limb is the most commonly reported musculoskeletal location with pain and also the most commonly injured site in sports. Some potential risk factors have been studied, but the results are inconsistent. We hypothesized that distinction of traumatic from non-traumatic pain would provide a clearer picture of these factors. The aim of this study is to assess factors associated with lower extremity pain and its impact on preadolescents in a population-based cohort. METHODS: A structured pain questionnaire was completed by 1756 schoolchildren of third and fifth grades to assess musculoskeletal pain, psychosomatic symptoms, subjective disabilities, school absence and frequency of exercise. In addition, hypermobility and physical fitness were measured. RESULTS: The knee was the most common site of pain followed by the ankle-foot and thigh. Of the children who reported pain in their lower extremity, approximately 70% reported at least one disability and 19 % reported school absence attributed to their pain during the previous three-month period. Children with traumatic pain had a higher subjective disability index than those with non-traumatic pain (P = 0.02). Age less than 11 years, headache, abdominal pain, depressive feelings, day tiredness, and vigorous exercise were more common in children with lower limb pain than those free of it. In the stratified analysis, younger age was related to both traumatic and non-traumatic pain groups. Vigorous exercise was positively associated with traumatic pain, while subjects with non-traumatic pain had more frequent psychosomatic symptoms. CONCLUSION: Risk factors and consequences of traumatic and non-traumatic lower limb pain are not similar. Traumatic lower limb pain is associated with practicing vigorous exercise and high level of physical fitness, while non-traumatic pain is more correlated with psychosomatic symptoms. These differences might be one of the reasons for the discrepancy of previous research conclusions. The two conditions need to be treated as different disorders in future studies

In Vivo Investigation of the Ameliorating Effect of Copper Albumin Complex on chondroitin sulfate in Monosodium iodoacetate -Induced Knee Osteoarthritis

Osteoarthritis (OA) is a condition that manifests as cartilage deterioration and subchondral bone sclerosis in the joint tissues. The weight-bearing joint is most severely impacted by OA. According to some research, consuming foods high in copper albumin complex (cu-albumin complex) can help with OA-related joint degeneration and pain relief. The current study's objective to determine how oral administration of the cu-albumin complex as an anti-inflammatory medication affected the development of rat knee osteoarthritis (KOA). Fifty adult albino rats were divided into three groups: negative control untreated (n= 10, no KOA induction); positive untreated control (n= 20, KOA induction); and treated group (n= 20, KOA induction with administration of cu-albumin complex). According to the severity of the clinical symptoms, treated and untreated arthritic groups were equally divided into mild and severe groups (n=10). Monosodium iodoacetate (MIA) was used as intra-articular injection for osteoarthritis induction. Rats were euthanized after a month of the beginning of the experiment, and the joints were examined histopathologically and immunohistochemically. It was indicated that the treatment was effective in reducing KOA severity and in improvement of chondroitin sulfate of the affected cartilages. In conclusion, the structure of the chondroitin sulphate in the knee joint cartilages of KOA-affected rats was modified by the cu-albumin complex

Investigation of the Ameliorating Effect of Copper Albumin Complex on Lysyl oxidase in monosodium iodoacetate -Induced Knee Osteoarthritis in Rats

Knee osteoarthritis (KOA) is a common type of joint degeneration which causes progressive damage of the joint structure and has less therapeutic options. It has been found that oral consumption of Copper Albumin Complex as anti-inflammatory drug has a positive effect on the treatment of joint deterioration. The present study aimed to investigate the effect of oral administration of Copper Albumin Complex (cu-albumin complex) on Lysyl oxidase (LOX) which acts as a protective factor in KOA. Fifty adult albino rats were divided into 3 groups: negative control (10 normal rats); positive control (20 rats with KOA which left without induction treatment); and treated group (20 rats with KOA which treated with administration of copper albumin complex). Treated and untreated arthritic groups were subdivided equally into mild and severe groups (10 rats for each) according to the severity of clinical signs. KOA was induced by intra-articular injection of monosodium iodoacetate (MIA). At the experimental end, the joints were examined histopathologically and immunohistochemically after cervical dislocation of rats. It was observed that the treatment with CU- was effective in reducing disease severity and in improvement of Lysyl oxidase KOA. It was concluded that Copper albumin complex has a positive effect in the improvement of LOX of Knee joint cartilages of rats affected by osteoarthritis (OA)

Risk factors for development of non-specific musculoskeletal pain in preteens and early adolescents: a prospective 1-year follow-up study

Background Musculoskeletal pain symptoms are common in children and adolescents. These symptoms have a negative impact on children's physical and emotional well-being, but their underlying aetiology and risk factors are still poorly understood. Most of the previous cohort studies were conducted among mid and/or late adolescents and were mainly focused on a specific pain location (e.g. low back pain or neck pain). The purpose of this study is to estimate occurrence of new-onset pain symptoms, in all musculoskeletal locations, in preteens and early adolescents and investigate risk factors for development of these symptoms. Methods 1756 schoolchildren (mean age 10.8) were recruited from schools in southern Finland. Information was extracted as to whether they experienced musculoskeletal pain and a total of 1192 children were identified as free of musculoskeletal pain symptoms. Information was collected on factors which could potentially predict the development of musculoskeletal pain: headache, abdominal pain, sadness/feeling down, day-time tiredness, difficulty in falling asleep, waking up during nights, level of physical activity and hypermobility. These children were followed-up 1-year later and those with new episodes of non-traumatic and traumatic musculoskeletal pain symptoms were identified. Results A total of 1113 schoolchildren (93% of baseline pain-free children) were found at one-year follow-up. New episodes of musculoskeletal pain were reported by 21.5% of these children. Of them 19.4% reported non-traumatic pain and 4.0% reported traumatic pain. The neck was the most commonly reported site with non-traumatic pain, while the lower limb was the most common site for traumatic pain. The independent risk factors for non-traumatic musculoskeletal pain were headache (OR = 1.68, [95% CI 1.16–2.44]) and day-time tiredness (OR = 1.53, [95% CI 1.03–2.26]). The risk factors for traumatic musculoskeletal pain were vigorous exercise (OR = 3.40 [95% CI 1.39–8.31]) and day-time tiredness (OR = 2.97 [95% CI 1.41–6.26]). Conclusion This study highlights that there may be two types of pain entities with both distinct and common aspects of aetiology. For primary prevention purposes, school healthcare professionals should pay attention to preteens and early adolescents practicing vigorous exercise (predictor of traumatic pain), reporting headache (predictor of non-traumatic pain) and reporting day-time tiredness (predictor of both types of pain).BioMed Central Open acces