Phosphate Coatings Suitable for Personal Protective Equipment

Phosphate coatings can improve the corrosion resistance of carbon steel equipment such as carabiners. The specific porosity of the phosphate layer allows the deposition of an elastomer-based paint for absorbing mechanical shocks. The book is relevant for fundamental and applied research in the field of protective phosphate layers and their industrial applications. It also describes how to design and develop phosphating solutions that differ in the type and concentration of metal ions dissolved in phosphoric acid.

Improving Robustness of Legged Robots Against Mechanical Shock Using Impulsive Dynamics

This manuscript presents a method to calculate and analyze mechanical shock of a multi-rigid body system, based on the revised concept of the center of percussion and a newly derived variable called the radius of percussion. The objective is to improve the mechanism’s robustness against mechanical shocks that are caused by certain impacts, such as those experienced by legged robots from landing a jump or making a step. In practice, it can be used for placement of shock-sensitive components in robots, such as inertial measurement units and cameras, and for mechanical and controller design improvements and optimizations that aim to reduce shock in certain body parts. Several case studies are presented to support the usefulness of the theory.

Simulation of Hydraulic Cylinder Cushioning

The internal cushioning systems of hydraulic linear actuators avoid mechanical shocks at the end of their stroke. The design where the piston with perimeter grooves regulates the flow by standing in front of the outlet port has been investigated. First, a bond graph dynamic model has been developed, including the flow throughout the internal cushion design, characterized in detail by computational fluid-dynamic simulation. Following this, the radial movement of the piston and the fluid-dynamic coefficients, experimentally validated, are integrated into the dynamic model. The registered radial movement is in coherence with the significant drag force estimated in the CFD simulation, generated by the flow through the grooves, where the laminar flow regime predominates. Ultimately, the model aims to predict the behavior of the cushioning during the movement of the arm of an excavator. The analytical model developed predicts the performance of the cushioning system, in coherence with empirical results. There is an optimal behavior, highly influenced by the mechanical stress conditions of the system, subject to a compromise between an increasing section of the grooves and an optimization of the radial gap.

Chronic traumatic encephalopathy in military and sportsists: a factual problem?: a systematic review

Background: Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease linked to tau protein associated with recurrent brain trauma, clinically marked by mood, personality, cognitive and behavioral changes. Objectives: The objective of the study was to demonstrate whether athletes and military personnel can really be victims of CTE and to elucidate this same pathology. Design and setting: This is a systematic review, based on the PRISMA guidelines and a literature review with a summary of the evidence found. Methods: Articles were selected, published from 1934 to 2020, in PubMed and Scielo using the descriptors: “chronic traumatic encephalopathy”, “cerebral concussion”, “players”, “boxers”, “athletes” and “military”. Inclusion criteria were: studies available in English, Spanish and Portuguese published, with randomized clinical trial, cohort study or meta-analysis. Results: In 52 articles, 14 were selected for qualitative synthesis in the results table that addresses chronic traumatic encephalopathy in football, soccer and rugby players, boxers and the military. Neuropathologically, CTE is characterized by cerebral atrophy, a pelvic septum cavity with fenestrations, dense diffuse immunoreactive inclusions and a TDP-43 proteinopathy. Microscopically, there are extensive neurofibrillary tangles and spindle-shaped and filiform neurites throughout the brain. Conclusions: American football players, boxers and military men are more likely to trigger CTE, due to the constant mechanical shocks from their heads. The most frequent clinical manifestations were: headache, aggression, dementia, executive dysfunction and suicide. CTE is definitely diagnosed only at autopsy.

Simulation and Mathematical Description of Mechanical Shocks Caused by Brake Actuation on Electric Motors

When a brake engages or releases on an electric motor, a mechanical shock is generated. These so-called brake shocks propagate across the motor housing and the motor shaft, affecting safety relevant mechanical and electronic components. The nature of the interference may be irreversible, i.e. mechanical damage, or reversible, e.g. interference of signal measurement or data transmission. Especially component failures or faulty signal values on rotary encoders are undesirable from a safety point of view. Current shock testing procedures are insufficient to simulate real brake shock characteristics and to identify valid shock limits regarding these shocks. In the first part of this paper, the characteristics of brake shocks are presented and compared to pyroshocks with similar characteristics. Furthermore, it shows that the Pseudo-Velocity Shock Response Spectrum (PVSRS) appears to be the best mathematical method to describe the severity of brake shocks with respect to their potential of damaging encoder components or influencing electrical signals. In the second part a testing machine will be introduced, which is able to generate mechanical shocks with comparable characteristics of real mechanical brake shocks for up to several million cycles. During further research, endurance tests shall be performed with the machine to determine the resilience of safety-related components against mechanical brake shocks. The long-term goal is to define scientifically confirmed test criteria for a standardized shock testing procedure to be applied on safety-related components on electric motors. It is intended to include this testing procedure in an international safety-related standard, like IEC 61800-5-3.

Phosphate Surface Treatment for Improving the Corrosion Resistance of the C45 Carbon Steel Used in Carabiners Manufacturing

This study approaches the issues which appear during carabiner use and analyses the possibility to eliminate them. Therefore, to improve the corrosion resistance of carbon steel, used in carabiners manufacturing, three different insoluble phosphate layers were deposited on the samples’ surface. The layers were obtained by immersion in zinc-based phosphate solution, zinc/iron-based phosphate solution and manganese-based phosphate solution, Afterwards, to protect against mechanical shocks, a layer of elastomer-based paint was deposited. Furthermore, to reduce rope wear by decreasing the value of the coefficient of friction, the samples were impregnated in molybdenum disulfide-based lubricant. This study aims to analyse the corrosion behaviour of the layers deposited on the carbon steel surface in three of the most common corrosive environments (rainwater, seawater and fire extinguishing solution) by linear and cyclic polarisation. The overall results show that all types of deposited layers increase the corrosion resistance of C45 steel. The experimental results revealed that the samples coated with a phosphate layer obtained by immersion in the zinc-based phosphate solution possess the highest corrosion resistance among the phosphate samples.

A Review on Ergonomics in Agriculture. Part II: Mechanized Operations

Background: Musculoskeletal disorders (MSDs) have long been recognized as the most common risks that operation of agricultural machineries poses, thus, undermining the ability to labor and quality of life. The purpose of this investigation was to thoroughly review the recent scholarly literature on ergonomics in agricultural mechanized operations; Methods: Electronic database research over the last ten years was conducted based on specific inclusion criteria. Furthermore, an assessment of the methodological quality and strength of evidence of potential risk factors causing MSDs was performed; Results: The results demonstrated that ergonomics in agriculture is an interdisciplinary topic and concerns both developed and developing countries. The machines with driving seats seem to be associated with painful disorders of the low back, while handheld machines with disorders of the upper extremities. The main roots of these disorders are the whole-body vibration (WBV) and hand-arm transmitted vibration (HATV). However, personal characteristics, awkward postures, mechanical shocks and seat discomfort were also recognized to cause MSDs; Conclusions: The present ergonomic interventions aim mainly at damping of vibrations and improving the comfort of operator. Nevertheless, more collaborative efforts among physicians, ergonomists, engineers and manufacturers are required in terms of both creating new ergonomic technologies and increasing the awareness of workers for the involved risk factors.

The Efects of Kinetotherapy in the Recovery of Patients with Gonartrosis

Gonarthrosis is one of the most frequent forms of degenerative rheumatism, characterized bybenign evolution andprognosis. Itequally interests both sexes, manifesting itself around the age of 40, and affecting mostly the elderly population. The disease appears as a consequence of the wearingaway of the epiphyseal cartilages, which lose their elasticity and resistance due to mechanical shocks during walking.The localization of the osteoarthritic process at the knee level is considered to be the most common, and, according toits gender based incidence pool, women are by far the most affected, especially after entering menopause. The degenerative osteoarthritic process of the knee is the result of an imbalance between the resistance of the joint structures and the stressorsthey are subjected to.In contrast to hiposteoarthritis, knee osteoarthritis could transform intoa dysfunctional disease early on, due to pain and impaired muscular strength, especially of the leg extensors. It is true, however, that severe degenerative, dysfunctional forms can be found almost exclusively in secondary gonarthrosis, caused by misalignments (genuvarum, valgum, etc.), meniscopathies, ligamentous instability, traumas interesting intra-articular bone insertion, chronic nonspecific or specific inflammatory articular processes, endocrine-metabolic disorders.Starting from these assumptions and taking into account the number of people searching treatment for this condition, we believed that thorough theoretical and practical research was needed regarding the efficiency of kinetotherapyin slowing down the evolutionary process of the disease.

Effect of Mechanical Vibrations During Transport Operations of Nilo Tilapia (Oreochromis niloticus)

Oscillatory movements present in the transport of live fish may compromise the physiological stability and the future performance of the animals. Therefore, the objective of this research was to evaluate the effect of mechanical vibrations in the transport of Nile tilapia through vibration levels and shocks occurred in transport boxes previously installed in a truck. The research was carried out in a fish farming integrating company in the state of Ceará, Brazil, with the monitoring of 5 live fish loads. The transport truck used was of the open type, with capacity for five boxes of fiberglass with a useful volume of 2400 L, density of 236 kg m-3. The data were recorded through five dataloggers, to monitor the vibration level (m s-2) and the occurrence and amplitude of mechanical shocks on the roads. Hematological, metabolic and ionic responses of fish were evaluated as well as visual observations of physical injuries. The most intense shocks occurred with the truck between 60 and 80 km h-1, with vibrations 1.151 m s-2 in the transport box, as well as in the water 0.489 m s-2. Larger vibration levels occurred on the asphalt road, with an average value of 1.13 m s-2, while on the dirt road they registered an average of 0.57 m s-2. Vibratory and mechanical stimuli presented secondary responses to blood level stress with alterations in glycemia, hematocrit, hemoglobin and magnesium ions. Physical lesions with 34% severe and 21% moderate, showed an uncomfortable environmental condition to fish.

Protein folding modulates the adhesion strategy of Gram positive pathogens

Gram positive bacteria colonize mucosal tissues against large mechanical perturbations, such as coughing, which generate large shear forces that exceed the ability of non-covalent bonds to remain attached. To overcome these challenges, the pathogen Streptococcus pyogenes utilizes the protein Cpa, a pilus tip-end adhesin equipped with a Cys-Gln thioester bond. The reactivity of this bond towards host surface ligands enables covalent anchoring of the bacterium, allowing it to resist large mechanical shocks; however, colonization also requires cell migration and spreading over surfaces. The molecular mechanisms underlying these seemingly incompatible requirements remain unknown. Here, we demonstrate a magnetic tweezers force spectroscopy assay that resolves the dynamics of Cpa thioester bond under force. While folded at forces < 6 pN, Cpa thioester bond reacts reversibly with amine ligands, of common occurrence in inflammation sites; however, mechanical unfolding and exposure to forces higher than 35 pN blocks thioester reactivity entirely. We propose that this folding-coupled thioester reactivity switch allows the adhesin to hop and sample host surface ligands at low force (nomadic mobility phase), and yet gets covalently anchored in place while under mechanical stress (locked phase). We dub such bonds “smart covalent bonds”, adding a novel class to the known repertoire of non-covalent adhesion strategies that include slip bonds, and catch bonds.