Friction and wear performance of polyether ether ketone (PEEK) polymers in three lubrication regimes

This experimental study investigates the friction and wear of three coatings commonly used in industrial applications, particularly in hydrodynamic bearings. The three materials under investigation were Babbitt, polyether ether ketone (PEEK) reinforced with 15% carbon fibers, and PEEK reinforced with 20% carbon fibers. The first polymer material was extruded, while the other was produced by fused deposition modelling (FDM). The materials were subjected to sliding tests in a pin-on-disc configuration, with a steel ball serving as the counter surface. The tests were conducted at room temperature, with a load of 10 N and under three different lubrication conditions: dry, grease, and oil. The linear speed was set at 0.3 m/s for the dry and semi-solid lubrication tests, while for the oil tests, the speed was set at 0.25 m/s. The greases used had consistency grades of NGLI 000 and NGLI 2. An ISO VG 68 circulation oil was used for the oil lubrication tests. Additionally, thermodynamic analyses were performed under the most severe conditions (i.e., dry) to investigate the steel–Babbitt and steel–PEEK contact

Facing complications of direct anterior approach in total hip arthroplasty during the learning curve

This study aims to evaluate complications and early postoperative clinical outcomes of direct anterior approach (DAA) in total hip arthroplasty (THA)

Two cases of failed back surgery syndrome after correction and stabilization surgery for scoliosis with Harrington instrumentation

We report two cases of adjacent segment degeneration in patients with idiopathic scoliosis who underwent surgical treatment with Harrington instrumentation in young age. Both patients developed a symptomatic degeneration of the disk immediately under the last stabilized level and were treated with decompression and stabilization. Clinical and radiological results are satisfactory at the follow-up

Impalement injuries of the shoulder: a case report with literature review

The management of penetrating skeletal extremity trauma is a clinical challenge even for experienced surgeons. While the treatment of associated vascular injuries should be prioritized, there is still a lack of evidence regarding the management of foreign bodies in case of bone fractures or neurological injuries. Here we present a case of impalement of the right proximal humerus with a construction steel rod. The 54-year-old man was successfully treated without vascular, neurological, and thoracic sequelae. A review of the current literature about the most appropriate extrication sequences and soft tissue reconstruction following massive foreign body injuries was carried out

Chronic Giardia intestinalis infection presenting with clinical features mimicking lichen planus.

Sir, Human giardiasis, caused by Giardia intestinalis, a agellate protozoan parasite that colonizes the small bowel, is a worldwide infection (1). Giardia infection is usually asymptomatic but intestinal illness may occur (2–5). Several reports describe the association of allergy with increased levels of total serum IgE antibodies and of speci c IgE antibodies against food allergens in patients aVected by giardiasis, and Giardia infection may determine altered absorption of food antigens causing allergic sensitization (6). Cutaneous signs may be virtually indistinguishable from those of atopic dermatitis (7, 8). Acute reactions such as urticaria or asthma have also been described (9–11). We here report a patient aVected by giardiasis, with lichen-planus-like lesions as the sole clinical feature

nLCA in bakery food products: state of the art and urgent needs

This study analyzes the nutritional life cycle assessment (LCA) of bakery products and the current state of the art. The analysis focuses on (1) the importance of applying a methodology, such as LCA, in a general way and the division into different stages considering the UNI EN ISO; (2) the development of nutritional LCA; (3) the difference between functional units in LCA and nutritional LCA; and (4) the different nutritional LCA approaches. The study emphasizes the lack of nutritional LCA studies regarding the bakery category, underlining the urgent need for this type of investigation concerning this specific food sector

Environmental micro-niche filtering shapes bacterial pioneer communities during primary colonization of a Himalayas' glacier forefield

The pedogenesis from the mineral substrate released upon glacier melting has been explained with the succession of consortia of pioneer microorganisms, whose structure and functionality are determined by the environmental conditions developing in the moraine. However, the microbiome variability that can be expected in the environmentally heterogeneous niches occurring in a moraine at a given successional stage is poorly investigated. In a 50 m2 area in the forefield of the Lobuche glacier (Himalayas, 5050 m above sea level), we studied six sites of primary colonization presenting different topographical features (orientation, elevation and slope) and harbouring greyish/dark biological soil crusts (BSCs). The spatial vicinity of the sites opposed to their topographical differences, allowed us to examine the effect of environmental conditions independently from the time of deglaciation. The bacterial microbiome diversity and their co-occurrence network, the bacterial metabolisms predicted from 16S rRNA gene high-throughput sequencing, and the microbiome intact polar lipids were investigated in the BSCs and the underlying sediment deep layers (DLs). Different bacterial microbiomes inhabited the BSCs and the DLs, and their composition varied among sites, indicating a niche-specific role of the micro-environmental conditions in the bacterial communities' assembly. In the heterogeneous sediments of glacier moraines, physico-chemical and micro-climatic variations at the site-spatial scale are crucial in shaping the microbiome microvariability and structuring the pioneer bacterial communities during pedogenesis

The stage of soil development modulates rhizosphere effect along a High Arctic desert chronosequence

In mature soils, plant species and soil type determine the selection of root microbiota. Which of these two factors drives rhizosphere selection in barren substrates of developing desert soils has, however, not yet been established. Chronosequences of glacier forelands provide ideal natural environments to identify primary rhizosphere selection factors along the changing edaphic conditions of a developing soil. Here, we analyze changes in bacterial diversity in bulk soils and rhizospheres of a pioneer plant across a High Arctic glacier chronosequence. We show that the developmental stage of soil strongly modulates rhizosphere community assembly, even though plant-induced selection buffers the effect of changing edaphic factors. Bulk and rhizosphere soils host distinct bacterial communities that differentially vary along the chronosequence. Cation exchange capacity, exchangeable potassium, and metabolite concentration in the soil account for the rhizosphere bacterial diversity. Although the soil fraction (bulk soil and rhizosphere) explains up to 17.2% of the variation in bacterial microbiota, the soil developmental stage explains up to 47.7% of this variation. In addition, the operational taxonomic unit (OTU) co-occurrence network of the rhizosphere, whose complexity increases along the chronosequence, is loosely structured in barren compared with mature soils, corroborating our hypothesis that soil development tunes the rhizosphere effect

Development and reproductive performance of Hereford heifers of different frame sizes up to mating at 14-15 months of age

ABSTRACT Body development and reproductive performance of a hundred forty-two 14 to 15-month-old heifers, classified at weaning according to frame size as small, medium, and large, were evaluated. The parameters evaluated were: body weight, hip height, body condition score, weight gain, ovarian activity, and pregnancy rate. At weaning, body weight and hip height were significantly different among frame scores, (small – 133.0 kg, 92.2 cm; medium – 158.5 kg, 96.6 cm; and large – 185.2 kg; 100.2 cm). After weaning, heifers grazed together on natural pastures during the autumn and on ryegrass (Lolium multiflorum La.) during the winter and spring. Frame score differences remained until the beginning of the breeding season (BS), starting on average at 14 months of age. Weight gain between weaning and the beginning of BS was not different among frame scores (0.740 kg/day, on average). Body weights at the beginning of the BS were significantly different, of 255.7 kg (53.3% of the mature weight) for small heifers, 285.0 kg (59.4%) for medium heifers, and 307.6 kg (64.1%) for large heifers. Ovarian activity at the beginning of the BS was not different among the three groups. The average weight gain values during the BS of 0.492, 0.472, and 0.421 kg/day for small, medium, and large heifers, respectively, were significantly different. Pregnancy rates were not different among groups (small, 71.4%; medium, 76.4%; and large, 76.5%). Frame score did not influence the reproductive performance of heifers, but the small and medium heifers conceived 29 and 20 days earlier, respectively, than the large heifers

Field-Resolved Detection of Terahertz Pulses Based on a Four-Wave Mixing Nonlinearity

RÉSUMÉ: Le développement intense que la technologie térahertz (THz) a connu au cours des dernières décennies a donné accès à de multiples techniques pour générer et détecter ces champs à basse fréquence. Un tel progrès est le résultat d’un effort considérable des chercheurs, encouragés par les nombreuses signatures spectrales moléculaires trouvées dans cette gamme et par la faible énergie portée par ces photons; caractéristiques qui sont exploitées dans diverses applications telles que la spectroscopie en domaine temporel, l’imagerie, les inspections non destructifs, etc. Outre l’échantillonnage électro-optique (EOS), une des stratégies les plus diffuses pour détecter de manière cohérente les champs THz, une autre approche a attiré de plus en plus d’attention ces derniers temps et consiste en la détection homodyne d’un signal défini terahertz-field-induced second-harmonic (TFISH ). Contrairement à l’EOS, dont les spectres correspondants sont déformés en raison des interactions avec les phonons dans les cristaux, la détection basée sur TFISH n’est pas affecté par ce problème et le mélange avec un champ d’oscillateur local (LO) externe offre la possibilité de combler potentiellement l’écart entre détection THz classique et quantique, en donnant accès aux deux quadratures du champ électromagnétique. L’objectif principal de ce travail était de concevoir, assembler et optimiser une configuration optique pour la détection résolue en champ des impulsions THz basée sur le processus TFISH dans des materiaux à l’état solide. Après avoir été générés via rectification optique (OR), une non-linéarité d’ordre deux, stimulée par une source laser à 1550 nm émettant des impulsions de 50 fs, les impulsions THz ont d’abord été caractérisés via EOS pour assurer un processus performant de génération et faciliter la réussite de la preuve-de-principe de détection du signal TFISH. Pour une détection efficace, il était nécessaire d’affiner les optiques de focalisation et de collimation et de sélectionner les matériaux appropriés pour le processus TFISH au travers des simulations numériques des conditions d’adaptation de phase. La détection des ces champs à basse fréquence, générés via OR dans un substrat de ZnTe de 500 µm d’épaisseur, a été réalisée via un mélange linéaire du signal TFISH et un biais de seconde-harmonique, avec un bon rapport signal sur bruit (SNR de 25 avec un temps d’intégration de 500 ms pour chaque point de données) et incluant des composantes spectrales comprises principalement entre 0,5 et 2,5 THz, comparables à la bande passante obtenue avec la méthode EOS. ABSTRACT: The intense development that terahertz (THz) technology experienced during the last few decades gave access to multiple techniques to generate and detect these low-frequency fields. Such progress is the result of an extensive effort put by researchers, encouraged by the numerous molecular spectral signatures found within this range and by the low energy carried by these photons, features that are exploited in various applications such as time-domain spectroscopy, imaging, nondestructive inspections, etc. Besides electro-optic sampling (EOS), one of the most diffuse strategies to coherently detect THz transients, another approach has gained more and more attention lately and it consists in the homodyne detection of the so called terahertz-field-induced second-harmonic (TFISH) signal, induced by a four-wave mixing process. Conversely to EOS, whose corresponding spectra are distorted due to inter-actions with phonons in the crystals, the TFISH-based detection is “vibration-free” and the mixing with an external local oscillator (LO) field yields the opportunity to potentially bridge the gap between classical and quantum THz sensing, by giving access to both generalized quadratures of the electromagnetic field. The main objective of this work was to conceive, assemble and optimize an optical setup for field-resolved detection of THz pulses based on the TFISH process in solid-state media. After being generated via optical rectification (OR), a second-order nonlinearity, driven by a 1550 nm laser source emitting 50 fs pulses, the THz transients were first characterized via EOS to set a benchmark of our THz source and to ensure a proper generation process, facilitating the successful proof-of-principle detection of the TFISH signal. For efficient detection, it was necessary to fine-tune the focusing and collection optics and to determine suitable materials for the TFISH process via numerical simulations of the corresponding phase matching conditions. Detection of the low-frequency transients, generated via OR in a 500 µm thick ZnTe substrate, was achieved via linear mixing of the TFISH signal with a second-harmonic bias, with a decent signal-to-noise ratio (SNR of 25 with 500 ms integration time for each data point) and with spectral components comprised mainly between 0.5 and 2.5 THz, comparable with the bandwidth obtained via EOS measurements. Distortions in the temporal trace, particularly the long-lasting oscillations after the trailing edge, and the appearance in the corresponding spectrum of narrow spectral drops, matching some of the strongest tabulated water vapor resonances, suggested that the generated THz field excited some of the vibrational modes of water vapor molecules