A huge part of corrosion failures and even of catastrophes takes origin from a trivial mistake in either choice or connection of different materials, as well as from an inaccurate evaluation of the compatibility between materials an environment. The example shown in the present paper summarizes several wrong solutions due to the lack of knowledge of the basic rules of corrosion control. By chance, either the consequences of such mistakes were so precocious that it was possible to find a remedy during the construction, or they were happily so venial as to be tolerated. This paper is third in a series devoted to enhancing the need of a professional corrosion control design for infrastructures.

In diabetic foot infections (DFI), the clinically virulence of skin commensals are generally pre-sumed to be of low virulence. In this single-center study, we divided the wound isolates into two groups: skin commensals (coagulase-negative staphylococci, micrococci, corynebacteria, cutibacteria); and, pyogenicpathogenic pathogens, and followed the patients for ≥ 6 months. In this retrospective study among 1,018 DFI episodes (392 [39%] with osteomyelitis), we identified skin commensals as the sole culture isolates (without accompanying pyogenicpathogenic patho-gens) in 54 cases (5%). After treatment (antibiotic therapy [median of 20 days], hyperbaric oxy-gen in 98 cases [10%]), 251 episodes (25%) were clinical failures. Group comparisons between those growing only skin commensals and controls found no difference in clinical failure (17% vs 24 %, p=0.23) or microbiological recurrence (11% vs 17 %, p=0.23). The skin commensals were mostly treated with non-beta-lactam oral antibiotics. In multivariate logistic regression analysis, isolation of only skin commensals was not associated with failure (odds ratio 0.4, 95% confi-dence interval 0.1-3.8). Clinicians might wish to consider these isolates as potential pathogens when selecting a targeted antibiotic regimen, which may equally base on oral non-beta-lactam antibiotic agents susceptible to the corresponding skin pathogens.

An effort was made to find a relationship between the ratio of average asperities height and lubricant thickness at the point of contact of rolling element ball bearings, and empirical equations to predict the life for bearings under constant motion. Two independent failure mechanisms were considered, fatigue failure and lubricant failure resulting in seizing of the roller bearing. A theoretical formula for both of these methods was established for the combined probability of failure using both of these failure mechanisms. Fatigue failure was modeled with the empirical equations of Lundberg and Palmgren and standardized in DIN/ISO281. The seizure failure, which this effort sought to investigate, was predicted using Greenwood and Williamson's theories on surface roughness and asperities during lubricated contact. These two mechanisms were combined, and compared to predicted cycle lives of commercial roller bearing, and a clear correlation was demonstrated. This effort demonstrated that the Greenwood-Williams theories on the relative height of asperities versus lubricant film thickness can be used to predict the probability of a lubricant failure resulting in a roller bearing seizing during use.

An effort was made to find a relationship between the predicted tribological conditions at the point of contact of ball bearings, and empirical equations to predict the life for bearings under constant motion. The model was modified to predict the temperature dependence, and compare rapid accelerations and decelerations with empirical extrapolations.

This conceptual article is aimed at evaluating the COVID19 impacts on the global economy and to postulating an ‘economic paradigm shift’. We argue that the existing economic, political, and trade principles have been challenged due to the global pandemic issue. We also compare the COVID19 impact on Western countries and Eastern countries with their control mechanisms. The emerging of new economies is due to the travel restrictions and disrupt of the global economies are discussed that pave a gateway to the economic paradigm shift. The article finally assesses the advent of 5G technology and its implications to face any future health threats that will lead to the next economic paradigm shift in the modern world.

The main purpose of this paper is to present a system to detect extrusion failures in Fused Deposition Modelling (FDM) 3D printers by sensing that the filament is moving forward properly. After several years using these kind of machines, authors detected that there is not any system to detect the main problem in FDM machines. Authors thought in different sensors and used the Weighted Objectives Method, one of the most common evaluation methods, for comparing design concepts based on an overall value per design concept. Taking into account the obtained scores of each specification, the best choice for this work is the optical encoder. Once the sensor is chosen, it is necessary to design de part where it will be installed without interfering with the normal function of the machine. To do it, photogrammetry scanning methodology was employed. The developed device perfectly detects the advance of the filament without affecting the normal operation of the machine. Also, it is achieved the primary objective of the system, avoiding loss of material, energy and mechanical wear, keeping the premise of making a low-cost product that does not significantly increase the cost of the machine. This development has made it possible to use the printer with remains coil filament, which were not spent because they were not sufficient to complete an impression and also printing models in two colours with only one extruder.

The present paper describes a study case of the failure investigation of Duplex stainless steel (UNS S31803) on the tube and tube sheet section of a shell and tube heat exchanger BEM TEMA type with seawater as the cooling medium. Although UNS S31803 offers high strength, high resistance to chloride-induced SCC, and high resistance to pitting attack in chloride environments, in this study case, the heat exchanger experienced some material degradation; 26 tubes were leaked and plugged on both sides, and scales plugged 76 tubes. The examination in this study case revealed the formation of biofilm inside the tubes, XRD examination revealed that the film contained aragonite (CaCO3), and by using microstructural examination on the inner surface of the tube, the austenite grains were preferentially attacked by crevice corrosion. In this case, the failure was caused by crevice corrosion, and crevice corrosion was enhanced by microbiological-induced corrosion (MIC). Recommendations to avoid similar failures are also suggested in this paper.

Streptococcus pneumoniae is one of the associated bacteria that can cause the rare but high mortality hematological disease known as purpura fulminans (PF) in both adults and children. Patients with PF can progress quickly to sepsis and multiorgan failure, especially in immunocompromised individuals and young children. Due to the thrombotic blockage of blood arteries in PF, there is diffuse intravascular thrombosis and hemorrhagic infarction of the skin, which evolves from ecchymosis to skin necrosis, risk of limb sequelae, sepsis and fatality. We present a case of a previously healthy 1-year and 9-month female who was admitted to the Intensive Care Unit of the National Institute of Infectious Diseases "Prof. Dr. Matei Balș"- Bucharest, Romania. The patient presented with erythematous patches on left upper limb and trunk, tachycardia, tachypnea, hypotension, anuria and altered sensorium with an indication of intubation for 8 Glasgow Coma Scale (GCS). Cerebrospinal culture grew Streptococcus pneumoniae serotype 1. She required peritoneal dialysis due to acute kidney injury (AKI) and surgeries for affected areas. After multiple organ system failures, our patient evolved rapidly to irreversible tissue necrosis and death. We aim to report a rare case of PF associated with pneumococcal meningoencephalitis in immunocompetent children to better appreciate the risk of fatal evolution when managing this disease in children. To date, few studies report favourable evolution. We discuss the etiology, rapid diagnosis and treatment of immunocompetent children with PF and the importance of interprofessional teams to increase the outcomes in patients with infectious diseases.

For many years, the programmable positioners have been widely applied in structures of modern electro-pneumatic final control elements. The positioner consists of an electro-pneumatic transducer, embedded controller and measuring instrumentation. Electro-pneumatic transducers that are used in positioners are characterized by a relatively short mean time-to-failure. The practical and economical method of a reasonable prolongation of this time is proposed in this paper. It is principally based on assessment and minimizing the effort of the embedded controller. For this purpose, were introduced: the control value variability, mean-time and the cumulative controller's effort. The diminishing of controller effort has significant practical repercussions, because it reduces the intensity of mechanical wear of the final control element components. On the other hand, the reduction of the cumulative effort is important in the context of process economy due to limitation of the consumption of energy of compressed air supplying the final control element. Therefore, the minimization of introduced effort factors has an impact on increasing the functional safety and economics of the controlled process. As a result of the performed simulations, the recommendations regarding the selection of the structure and tuning of positioner controller were elaborated. The simulations were performed in the Matlab-Simulink environment with the use of the liquid level control system in which a phenomenological model of a final control element was deployed. It has been proven that under appropriate conditions, it is possible to extend significantly the lifetime of the final control element and simultaneously enhance the control quality factors.

Reliability analysis techniques are customary standard tools that are used for evaluating the performance of different equipment and devices in order to minimize their downtime. To predict the reliability, life data from a sample that is satisfactorily representative of the equipment should be fitted to the suitable statistical distribution. The parameterized distribution may be used to estimate essential characteristics such as failure rate; and probability at a precise time, as well as system reliability. In the current study, Weibull++/ALTA software package is used as a novel tool to fit the available data set to estimate the best fitted probability density function (PDF) using Maximum Likelihood (MLE) for parameter estimation. The determined distributions are then assessed using goodness-of-fit test to define how well it fits the available data set. There are multiple methods for determining goodness-of-fit. Weibull distributions and their special cases’ parameters have an effect on life times.

The various methods used to choose the profile shift coefficients, primarily the so-called equalizations, were based on assumed advantages without physical evidence proving them. In this paper a new calculation method is presented for determining profile shift coefficient. The procedure gives the pair of values ​​of the profile shift coefficients, in which case, under the given load, the resulting bending stress will be of the lowest possible value.