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Oxide films produced from plasma electrolytic oxidation are porous in structure. While they have some passivating effect in Mg alloys, the pores still lead to corrosion over long periods of exposure. In this study, spray pyrolysis was used to seal the porous oxide layer developed through the plasma electrolytic oxidation method on Mg alloy AZ31. The PEO coating acted as a good base for the application of spray pyrolysis due to its morphology. Three different kinds of coatings were obtained using different precursors: zinc acetate for ZnO, phosphoric acid for phosphate (P), and a mixture of zinc acetate and sodium phosphate for ZnO+P. The corrosion performance of all three coatings was studied by performing electrochemical impedance and polarization tests on the samples. Mass loss over a duration of 1 week was measured in 3% NaCl solution using immersion gravimetry. The coating with only phosphate (P) was found to be most corrosion-resistant with 52 times lower rate of corrosion and 50 times more polarization potential. The chemical composition of the corrosion products was studied using XRD and SEM-EDS analysis. Mass loss in ZnO+P was the highest, at up to 1.4 and 5.1 times higher than ZnO and P, respectively.

The plasma electrolytic oxidation method was used with AZ31 magnesium alloy plates for improving the corrosion resistance of the alloy. Process parameters for the plasma electrolytic oxidation setup were optimized by studying the effects of KOH concentration, operating voltage, and pulse properties on the obtained coating. These conditions were then used to produce plasma electrolytic oxidation coated AZ31 sample and were tested by immersion in 3 % NaCl solution for 1 week. Three types of modifiers were used in the electrolyte and concentrations of the modifiers were varied to study the effect of concentration on the performance of coating obtained. The extent of corrosion was visually examined, and it was found that an electrolyte recipe with all three modifiers produced the best results.

Abstract Background Excitotoxicity is involved in the pathogenesis of a number neurodegenerative diseases, and axonopathy is an early feature in several of these disorders. In models of excitotoxicity-associated neurological disease, an excitotoxin delivered to the central nervous system (CNS), could trigger neuronal death not only in the somatodendritic region, but also in the axonal region, via oligodendrocyte N-methyl-D-aspartate (NMDA) receptors. The retina and optic nerve, as approachable regions of the brain, provide a unique anatomical substrate to investigate the "downstream" effect of isolated excitotoxic perikaryal injury on central nervous system (CNS) axons, potentially providing information about the pathogenesis of the axonopathy in clinical neurological disorders. Herein, we provide ultrastructural information about the retinal ganglion cell (RGC) somata and their axons, both unmyelinated and myelinated, after NMDA-induced retinal injury. Male Sprague-Dawley rats were killed at 0 h, 24 h, 72 h and 7 days after injecting 20 nM NMDA into the vitreous chamber of the left eye (n = 8 in each group). Saline-injected right eyes served as controls. After perfusion fixation, dissection, resin-embedding and staining, ultrathin sections of eyes and proximal (intraorbital) and distal (intracranial) optic nerve segments were evaluated by transmission electron tomography (TEM). Results TEM demonstrated features of necrosis in RGCs: mitochondrial and endoplasmic reticulum swelling, disintegration of polyribosomes, rupture of membranous organelle and formation of myelin bodies. Ultrastructural damage in the optic nerve mimicked the changes of Wallerian degeneration; early nodal/paranodal disturbances were followed by the appearance of three major morphological variants: dark degeneration, watery degeneration and demyelination. Conclusion NMDA-induced excitotoxic retinal injury causes mainly necrotic RGC somal death with Wallerian-like degeneration of the optic nerve. Since axonal degeneration associated with perikaryal excitotoxic injury is an active, regulated process, it may be amenable to therapeutic intervention.

Abstract Background Frontotemporal lobar degeneration (FTLD) represents a clinically, pathologically and genetically heterogenous neurodegenerative disorder, often complicated by neurological signs such as motor neuron-related limb weakness, spasticity and paralysis, parkinsonism and gait disturbances. Linkage to chromosome 9p had been reported for pedigrees with the neurodegenerative disorder, frontotemporal lobar degeneration (FTLD) and motor neuron disease (MND). The objective in this study is to identify the genetic locus in a multi-generational Australian family with FTLD-MND. Methods Clinical review and standard neuropathological analysis of brain sections from affected pedigree members. Genome-wide scan using microsatellite markers and single nucleotide polymorphism fine mapping. Examination of candidate genes by direct DNA sequencing. Results Neuropathological examination revealed cytoplasmic deposition of the TDP-43 protein in three affected individuals. Moreover, we identify a family member with clinical Alzheimer's disease, and FTLD-Ubiquitin neuropathology. Genetic linkage and haplotype analyses, defined a critical region between markers D9S169 and D9S1845 on chromosome 9p21. Screening of all candidate genes within this region did not reveal any novel genetic alterations that co-segregate with disease haplotype, suggesting that one individual carrying a meiotic recombination may represent a phenocopy. Re-analysis of linkage data using the new affection status revealed a maximal two-point LOD score of 3.24 and a multipoint LOD score of 3.41 at marker D9S1817. This provides the highest reported LOD scores from a single FTLD-MND pedigree. Conclusion Our reported increase in the minimal disease region should inform other researchers that the chromosome 9 locus may be more telomeric than predicted by published recombination boundaries. Moreover, the existence of a family member with clinical Alzheimer's disease, and who shares the disease haplotype, highlights the possibility that late-onset AD patients in the other linked pedigrees may be mis-classified as sporadic dementia cases.

Wearable devices, such as headsets and activity trackers, rely heavily on the Bluetooth and/or the Bluetooth Low Energy wireless communication standard to exchange data with smartphones or other peripherals. Since these devices collect personal health and activity data, ensuring the privacy and security of the transmitted data is crucial. Therefore, we present a dataset that captures complete Bluetooth communications—including advertising, connection, data exchange, and disconnection—in an RF isolated environment using software-defined radio. We were able to successfully decode the captured Bluetooth packets using existing tools. This dataset provides researchers with the ability to fully analyze Bluetooth traffic and gain insight into communication patterns and potential security vulnerabilities.

The article discusses the current state of development of supersonic transport, analyses the main limitation of the use of gas turbine engines when flying at high supersonic flight speeds, proposes a method for expanding the range of GTE limitations in these flight modes of the aircraft, using cold forcing of the engine, conducts an analytical study of the effectiveness of this approach, proposes one of the possible devices for the implementation of cold forcing, the efficiency of an engine with cold forcing is shown, which may be of significant interest for the application of cold forcing methods in gas turbine engines of supersonic transport.

This paper is a study on the results of strength tests on single-lap joints used primarily in the aerospace industry, based on a Hi-Lok fastener. Two popular structural materials used in the aerospace industry were considered in this work. The test specimens were fabricated from the EN-AW 2024 T3 aluminium alloy and a carbon composite. It was decided to use the Naftoseal MC780 type C adhesive as a sealant to form the required hermetic, air-tight lap joints. In the definition of the joint type used, the results are presented for the tests of selected 2D and 3D surface roughness parameters, with isometric imaging of the surfaces related to this analysis. Microscopic images acquired at a magnification of x500 illustrate the surface quality. This work concludes with a discussion of the test results and conclusions.

Printed circuit boards (PCBs) make up 3 to 5% of all electronic waste. The metal content of spent PCBs can reach 40%. They usually contain valuable metals, such as Ag, Au, and Pd, as well as other metals such as Cu, Sn, Pb, Cd, Cr, Zn, Ni, and Mn. However, the metallic part of a whole PCB is 40–60% including the Cu layers between the fiberglass–polymer layers. The paper describes the economics of the valuable metal (Ag, Au, Pd)-containing concentrate preparation from a raw PCB. We considered the influence of the pre-treatment method of PCBs before the extraction of valuable metals on the extraction self-cost change. The disintegration method is based on the high-energy impact of the particles of the material to be ground, thus causing the separation of the metallic components of the PCB. In the course of the work, single and double direct grinding using the method of disintegration was studied. For the calculation, the test batch of 10,000 kg of two types of PCB was taken for estimation of the self costs and potential profit in the case of complete valuable metals (Ag, Au, Pd) plus Cu extraction. It was shown that from 10,000 kg of studied PCB, it is possible to obtain 1144 and 1644 kg of metal-rich concentrate, which should be further subjected to electro-hydrochlorination for metals leaching. The novelty of this research lies in the fact that a technical and economic analysis has been carried out on a newly developed combined technology for processing electronic waste. This included mechanical processing and electrochemical leaching with the help of the active chlorine that is formed in situ. The real (not specially selected or prepared) waste PCBs were used for the process’s economical efficiency evaluation. The main findings showed that despite the high content of Cu in the studied PCBs, the commercial value was insignificant in relation to the total income from the Ag, Au, and Pd sale. A correlation was established between the self-cost decrease after separative disintegration of PCBs by metal content increase (by specific metals such as Au, Ag, Pd, and Cu) with the metal potential yield after extraction.

This study aims to optimize the 2-cylinder in-line reciprocating compressor crankshaft. As the crankshaft is considered the "bulkiest" component of the reciprocating compressor, its weight reduction is the focus of current research for improved performance and lower cost. Therefore, achieving a lightweight crankshaft without compromising the mechanical properties is the core objective of this study. Computational analysis for the crankshaft design optimization was performed in the following steps: kinematic analysis, static analysis, fatigue analysis, topology analysis, and dynamic modal analysis. Material retention by employing topology optimization resulted in a significant amount of weight reduction. A weight reduction of approximately 13% of the original crankshaft was achieved. At the same time, design optimization results demonstrate improvement in the mechanical properties due to better stress concentration and distribution on the crankshaft. In addition, material retention would also contribute to the material cost reduction of the crankshaft. The exact 3D model of the optimized crankshaft with complete design features is the main outcome of this research. The optimization and stress analysis methodology developed in this study can be used in broader fields such as reciprocating compressors/engines, structures, piping, and aerospace industries.

This paper presents the results of the leaching of metals from computer PCBs by electrochemical hydrochlorination using alternating current (AC) with an industrial frequency (50 Hz). Leaching was carried out with a disintegrator-crushed computer motherboard with a particle size (d) of HCl = 6 mol·L−1, i = 0.80 A·cm−2, S/L = 8.6 g·L−1), is reached after 1.5 h, and that of Cu and Ni is reached after 2 h from the beginning of the experiment. At the same time, the degree of leaching of other metals after 2 h is Co-78.8%, Cr-84.4%, Sb-91.7%, Fe-98.9%, V-98.1% and Pb-5.1%. The paper also reports the results on the leaching of all abovementioned metals, as well as Ag and Pd, with disintegrator-crushed mixed computer PCBs with d < 90 μm and loading option 1.

Lightweight magnesium alloys offer excellent benefits over Al alloys due to their high specific strength and damping properties, but they are more prone to galvanic corrosion. Plasma electrolytic oxidation (PEO) coatings reinforced by nanoparticles have been shown to improve corrosion resistance and possess better mechanical properties. A lot of research has been published that focuses on the effect of nanoparticle concentration in the PEO electrolyte solution, and the type of nanoparticle, on the properties obtained. The aim of paper is to study the effect of processing time on the nanoparticle-reinforced PEO coating on AZ31 magnesium alloy. TiN and SiC nanoparticles were produced using plasma chemical synthesis and added to KOH-based electrolyte to develop PEO coatings. The concentration of nanoparticles was kept constant at 0.5 g/L and the treatment time was varied as follows: 1, 2, 3, 5, and 10 min. The coatings were tested for their microstructure, phase, chemical makeup, nano-mechanical properties, and corrosion resistance. Nanoparticles were found to be clustered in the coating and spread unevenly but led to a decrease in the size and number of pores on the PEO coating surface. The corrosion resistance and nano-mechanical properties of the coating improved with treatment time. The hardness and contact modulus of coatings with TiN particles were 26.7 and 25.2% greater than those with SiC particles. Addition of TiN nanoparticles resulted in improved corrosion resistance of the PEO coatings when the processing time was 5 or 10 min. The lowest corrosion rate of 6.3 × 10−5 mm/yr was obtained for TiN-added PEO coating processed for 10 min.

Modern technologies for recycling electronic waste (e-waste) have high economic efficiency and environmental safety requirements. Among the existing technologies, hydrometallurgy is considered to be the most promising technology for e-waste recycling. Increasing attention paid to the chlorination method is associated with the complex recycling of low-grade ores containing noble metals and the raw materials of secondary polymetallic. In this paper, we propose a new scheme for leaching metals from computer printed circuit boards (PCBs) pre-crushed in a disintegrator: The processes of chlorine production and hydrochlorination are implemented in one reactor under the action of an alternating current (AC) of industrial frequency (50 Hz). Three fine fractions of raw material powders with particle size d < 90 µm, d = 90–180 µm, and d = 180–350 µm were used as research objects and the finest fraction of the raw material (d < 90 µm) was studied in more detail. It was found that complete leaching of gold is achieved from fractions of raw materials with a particle size d = 90–180 µm and d = 180–350 µm, containing 277 ppm and 67 ppm of the gold, respectively, at an experiment duration (tex) of 2 h, a current density (i) of 0.66 A·cm−2, and a solid/liquid (S/L) ratio of 8.6 g·L−1. Under the same conditions of the electrochemical leaching process from the fraction of raw materials with a particle size of d < 90 µm and a gold content of 824 ppm, the degree of metal leaching is 80.5%. At the same time, with an increase in particle size in the raw material fractions from d < 90 µm to d = 180–350 µm and a copper content in the raw material from 1.40% to 6.13%, an increase in the degree of its leaching from 81.6% to 95.2%, respectively, is observed. In the framework of the preliminary study presented in this work, for the finest raw material fraction with d < 90 μm the highest gold leaching degree (86.3%) was achieved under the following experimental conditions: tex= 4 h, CHCl = 6 M, i = 0.88 A·cm–2, S/L ratio—8.6 g·L–1 and the highest copper leaching degree (94.2%) was achieved under the following experimental conditions: tex = 2 h, CHCl = 6 M, i = 0.64 A·cm–2, and S/L ratio—2.9 g·L–1.

Various metals and semiconductors containing printed circuit boards (PCBs) are abundant in any electronic device equipped with controlling and computing features. These devices inevitably constitute e-waste after the end of service life. The typical construction of PCBs includes mechanically and chemically resistive materials, which significantly reduce the reaction rate or even avoid accessing chemical reagents (dissolvents) to target metals. Additionally, the presence of relatively reactive polymers and compounds from PCBs requires high energy consumption and reactive supply due to the formation of undesirable and sometimes environmentally hazardous reaction products. Preliminarily milling PCBs into powder is a promising method for increasing the reaction rate and avoiding liquid and gaseous emissions. Unfortunately, current state-of-the-art milling methods also lead to the presence of significantly more reactive polymers still adhered to milled target metal particles. This paper aims to find a novel and double-step disintegration–milling approach that can provide the formation of metal-rich particle size fractions. The morphology, particle fraction sizes, bulk density, and metal content in produced particles were measured and compared. Research results show the highest bulk density (up to 6.8 g·cm−3) and total metal content (up to 95.2 wt.%) in finest sieved fractions after the one-step milling of PCBs. Therefore, about half of the tested metallic element concentrations are higher in the one-step milled specimen and with lower adhered plastics concentrations than in double-step milled samples.

Background: Children generally have a higher nasal resistance than adults. Growth changes the size and different anthropometric parameters of the nose. Logarithmic effective resistance and logarithmic vertex resistance were introduced as physically correct parameters for nasal obstruction. The previously published classification of obstruction derived from 36,500 measurements is missing data for patients aged 7 to 19 years. Methodology: Rhinomanometry was performed before and after decongestion with 9 different anthropometric measurements in 225 children and adolescents. Correlations among age, anthropometric measurements, and logarithmic effective and vertex resistance were determined for both sexes, and regressions were calculated. Results: The highest correlations with the resistance values were found between age, lateral nasal length, and logarithmic effective resistance. A highly significant linear regression between age and logarithmic effective resistance was also found. This was used for adaption of the classification of obstruction in adults to growing patients. The resistance of the nasal airways at the age of 7 years was about twice that in adults. Conclusions: The linear regression equations can be used to suborder obstructions measured by four-phase rhinomanometry into classes for estimation of their severity according to age.

Acoustic emission (AE) technique is widely used to monitor failure processes in composite materials includ-ing development of cracks and plastic deformations within the polymer matrix, fracture and debonding of inclusions, etc. In this study, the AE technique was applied investigating failure character of epoxy polymers with different content of nanofiller – fine polyethersulfone (PES) powder. Variation of material properties of the epoxy with 0, 5%, 7.5%, 10%, and 12.5% concentration (by weight) of the PES was assessed experimentally. Correlation between the PES content and the modulus of elasticity was found negligible. The same was characteristic for the tensile strength. Whereas, such a correlation was found significant for the fracture toughness that increased 1.5 times concerning the pure epoxy reference. Analysis of the cumulative AE counts indicated existence of three different stages of the damage accumulation process, which were unidentified using the load and the deformation diagrams. In the PES-modified composites, the damage ac-cumulation process was evidenced at the 10–20% of the ultimate load; whereas, in the pure epoxy, such a process was fairly slow until the 85% of the loading.

This paper is devoted to issues related to strength determination and prediction of destructive processes of composites; these issues enable determining the limits of safe use of a product and to recognize when limits are reached. The model that was developed and is presented in this paper enables to describe not only the predictable strength of unidirectional composites, but also the character of the destruction, taking into account the fiber stress and/or ultimate strain distribution.