Search Results (55)

Copper (Cu) is widely used in electrical, electronic, and tribological systems owing to its excellent electrical and thermal conductivity. However, its relatively low hardness and poor wear resistance limit its use in demanding engineering applications. In this study, Cu-based hybrid metal matrix composites (MMCs) reinforced with hexagonal boron nitride (h-BN) and boron carbide (B₄C) were fabricated via spark plasma sintering (SPS) to improve their mechanical and tribological performance. The h-BN content was fixed at 1 wt.% to ensure solid lubrication, while the B₄C content was varied (0.25, 0.5, 0.75, and 1 wt.%) to examine its influence on the microstructural, mechanical, electrical, and wear properties of the composites. Microstructural analyses confirmed a homogeneous distribution of h-BN and B₄C particles in the Cu matrix at low and moderate reinforcement levels, whereas excessive B₄C resulted in partial agglomeration and reduced densification. All composites achieved relative densities above 95%, demonstrating the high densification efficiency of the SPS process. Hardness increased markedly with B₄C addition due to dispersion strengthening and grain refinement, while electrical conductivity decreased slightly because of the insulating nature of the reinforcements. Tribological tests showed that the composite containing 0.75 wt.% B₄C exhibited the best performance, with the lowest wear rate and stable friction behavior. Overall, the results indicate that co-reinforcing Cu with h-BN and B₄C through SPS is a promising strategy for developing multifunctional materials suitable for electrical contact and sliding applications. Full article

In this paper, the achieved state-of-the-art understanding regarding the wear behaviour of various PVD (physical vapour deposition) coatings deposited on TiB₂/Ti composites produced by SPS (spark plasma sintering) is presented. The objective of this paper is to investigate the wear behaviour of various PVD coatings deposited on TiB₂/Ti composites manufactured by SPS, when lubricated with hexagonal boron nitride (hBN) as an external solid lubricant in the range from room temperature up to 900 °C in friction contacts under extreme pressure and with oscillation relative motion. Four multicomponent and multilayer coatings were investigated based on AlCrN and TiCrN coatings with TiCrN-AlCrN/AlCrTiN/Si₃N₄ interlayers and various external layers (AlCrN, Si₃N₄, AlCrTiSiN, and AlCrTiSiN gradient with increasing oxygen gradient replacing nitrogen). The wear tests were performed by means of a ball-on-disc SRV friction and wear tester using reciprocating motion of the Si₃N₄ ball sliding against a coated disc from room temperature up to 900 °C. The best protection against wear and oxidation at higher temperatures (even up to 900 °C) was achieved for coatings with AlCrN and AlTiCrN external layers, and hBN lubricant was used simultaneously. Full article

Mexico has not only successfully eliminated dog-mediated human rabies in recent years, but also the last rabies case in a dog infected with the canine variant of the rabies virus was reported in 2016. Mass dog vaccination campaigns were the cornerstone of these achievements. Unfortunately, the rabies virus still circulates in wildlife and, thus, spill-over infections in humans, livestock, and pets, including dogs, still occurs. Especially dogs that cohabit at interfaces shared with wildlife, like shepherd dogs, are at risk. These dogs are often free-roaming and difficult to restrain for vaccination purposes. Oral rabies vaccination (ORV) as an alternative vaccination strategy was tested in several rural villages in Querétaro State, Mexico. Bait acceptance and immunogenicity studies were conducted to test a licensed vaccine bait in terms of attractiveness and if the oral rabies vaccine strain, SPBN GASGAS, was able to induce an adequate immune response in local dogs, respectively. Although the egg(-flavored) bait was less well accepted (68.4%) by the dogs than the two other bait types included in the study, a bait made from boiled intestine segments (71.2%) and a bait with fish meal as an attractant (72.3%), dogs offered the egg bait were more often considered successfully vaccinated. 83.3% of the dogs offered an egg bait seroconverted during the immunogenicity study. Hence, ORV can be a suitable alternative by increasing the overall vaccination coverage of dogs that cannot be easily restrained and handled for vaccination. Full article

Recent measurements of the band properties of AlN and GaN by fluorescence yield absorption and soft X-ray emission spectroscopies revealed that their valence band (VB) is composed of two separate subbands. The upper VB subband of GaN is composed of gallium sp and nitrogen p orbitals; the lower subband consists of metal d and nitrogen s orbitals. These findings were confirmed by extensive ab initio simulations. These results are not consistent with the standard tetrahedrally coordinated semiconductors, which are bonded by sp³-hybridized orbitals of metal and nonmetal atoms. The new analysis techniques and ab initio simulations create a new picture, allowing the calculation of overlap integrals to determine the bond order in these crystals. According to these results, bonding occurs between resonant p-states of nitrogen and sp³-hybridized metal orbitals in tetrahedral nitrides, allowing tetrahedral symmetry to be maintained. A similar resonant bonding mechanism is observed in hexagonal BN, where the p orbitals of nitrogen create three resonant states necessary for maintaining the planar symmetry of the lattice. In addition, nonresonant $\pi$-type bonds in BN are created by the overlap of $p_z$ orbitals of boron and nitrogen. BN bonding differs from that in graphene, where carbon states are fully sp²-hybridized. Additionally, $\pi$-type bonds in graphene have no ionic contributions, which leads to the formation of Dirac states with linear dispersion close to the K point, closing the band gap. Full article

Background/Objectives: Atopy and spondyloarthritis (SpA) are immune-mediated diseases driven by distinct T-helper (Th) cell pathways—Th2 for atopy and Th1/Th17 for SpA. The coexistence of these divergent immune responses is increasingly recognized, particularly in the context of biological therapies that target pro-inflammatory cytokines. This study aimed to investigate Th2 cytokine profiles (IL-4, IL-5, IL-13) in atopic SpA patients receiving biological therapy to better understand how such treatment may influence immune regulation in this complex clinical setting. Methods: We conducted a prospective observational cross-sectional study on 136 SpA patients stratified by biological therapy and atopy status. Serum IL-4, IL-5, and IL-13 levels were quantified using LUMINEX immunoassays. Patients were grouped into biologically treated (BT) and Bio-Naïve (BN) cohorts and further sub-categorized by atopic phenotype (allergic rhinitis, asthma, dermatitis). Statistical comparisons of cytokine levels were made using SPSS IBM version 26 to explore associations with clinical and demographic variables. Results: IL-13 levels were significantly elevated in BT-atopic patients, particularly those with allergic rhinitis and atopic dermatitis, suggesting biological therapy may modulate Th2 responses. IL-5 remained elevated in allergic asthma cases despite treatment, indicating persistent eosinophilic activity. No significant correlation was found between cytokine levels and disease duration or therapy length. Conclusions: Biological therapy in SpA may influence Th2 cytokine expression, notably IL-13, in atopic patients. These findings underscore the importance of immune profiling in guiding personalized treatment strategies and highlight the need for further investigation into the long-term immunomodulatory effects of biologics in patients with overlapping Th1/Th2-driven diseases. Full article

The reasonable design of low-cost, high-activity single-atom catalysts (SACs) is crucial for achieving highly efficient electrochemical CO₂RR. In this study, we systematically explore, using density functional theory (DFT), the performance of transition metal (TM = Mn, Fe, Co, Ni, Cu, Zn)-doped defect-type hexagonal boron nitride (h-BN) SACs TM@B₋₁N (B vacancy) and TM@BN₋₁ (N vacancy) in both CO₂RR and the hydrogen evolution reaction (HER). Integrated crystal orbital Hamiltonian population (ICOHP) analysis reveals that these catalysts weaken the sp orbital hybridization of CO₂, which promotes the formation of radical-state intermediates and significantly reduces the energy barrier for the hydrogenation reaction. Therefore, these theoretical calculations indicate that the Mn, Fe, Co@B₋₁N, and Co@BN₋₁ systems demonstrate excellent CO₂ chemical adsorption properties. In the CO₂RR pathway, Mn@B₋₁N exhibits the lowest limiting potential (U_L = −0.524 V), and its higher d-band center (−0.334 eV), which aligns optimally with the adsorbate orbitals, highlights its excellent catalytic activity. Notably, Co@BN₋₁ exhibits the highest activity in HER, while U_L is −0.217 V. Furthermore, comparative analysis reveals that Mn@B₋₁N shows 16.4 times higher selectivity for CO₂RR than for HER. This study provides a theoretical framework for designing bifunctional SACs with selective reaction pathways. Mn@B₋₁N shows considerable potential for selective CO₂ conversion, while Co@BN₋₁ demonstrates promising prospects for efficient hydrogen production. Full article

Sepsis is the leading cause of mortality in patients with burn injuries and it may represent, in these patients, a real diagnostic challenge. Here we studied the profile of miRNAs contained in extracellular vesicles (EVs) (EV-miRNAs) isolated from plasma from burn patients complicated by sepsis at admission and 7 days later. We enrolled 28 burn patients, 18 with (Burn Septic Patients—BSPs) and 10 without (Burn non-Septic Patients—BnSPs) sepsis. Ten healthy subjects (HSs) were used as additional controls. After EV isolation by charge precipitation and miRNA extraction, we proceeded with a two-phase approach. Through a first screening phase, we identified 178 miRNAs differentially expressed in BSPs compared to HSs. Among these, by a validation phase based on qRT-PCR, we found that miR-483-5p, miR-193a-5p, and miR-188-3p were increased in the BSPs compared to the BnSPs and HSs. Upon ROC analysis, all three miRNAs showed a good accuracy in differentiating BSPs from BnSPs, especially miR-483-5p (AUC = 0.955, p-value = 0.001). Moreover, we found 173 miRNAs differentially expressed in BSPs after 7 days from enrollment compared to T0, among whose miR-1-3p, miR-34a-3p, and miR-193a-5p decreased in BSPs after 7 days, in parallel with a decrease in SOFA scores. Finally, the other two miRNAs, miR-34a-3p and miR-193a-5p, positively correlated with the SOFA score. In conclusion, we identified several miRNAs—namely miR-483-5p, miR-193a-5p, and miR-188-3p—with potential clinical utility as diagnostic biomarkers in a heterogeneous population of burn patients at high risk of developing sepsis. Moreover, we found some miRNAs (miR-1-3p, miR-34a-3p, and miR-193a-5p) that vary according to the course of sepsis and others (miR-34a-3p and miR-193a-5p) that are associated with its clinical severity. Full article

The aim of this study was to investigate the microbiota composition and its potential interactions across seven gut locations (stomachs, jejuna, ilea, ceca, proximal colons, distal colons, and recta) in weaned pigs to identify key influencing microbiotas. To compare between microbiota compositions, 16S rRNA gene amplicon sequencing was performed. Six 70-day-old healthy crossbred (Duroc × Large White × Landrace) piglets were introduced as donors. A Bayesian network (BN) was used to examine the directional interactions among the microbiotas evaluated (seven mucosal and seven digesta microbiotas). Based on edge connectivity frequency, the microbiota in jejunal mucosa was the central hub node, influencing other microbiotas, especially the mucosal microbiotas of the ileum, cecum, distal colon, and rectum. The jejunal mucosa was dominated by Prevotella and lactobacilli, both recognized for their contributions to pig health. Among Prevotella, Prevotella copri and Prevotella sp. were predominant in jejunal mucosa (4.6% and 2.9%, respectively). Lactobacilli, including eight distinct species, were distributed throughout the gastrointestinal tract. Notably, Ligilactobacillus salivarius and Lactobacillus amylovorus, known as immune-enhancing bacteria, were abundant in jejunal mucosa (1.0% and 0.8%) and digestas (0.9% and 19.2%), respectively. The BN identified rectal mucosa and digestas as two terminal nodes, influenced by upstream microbiotas in the gastrointestinal tract. This finding supports the link between fecal microbiota and pig productivity, as the fecal microbiota, closely resembling the rectal microbiota, reflects the conditions of the microbiota throughout the gastrointestinal tract. Full article

This paper presents a comprehensive study of two tool materials designed for the machining of Inconel 718 superalloy, produced through two distinct sintering techniques: High Pressure–High Temperature (HPHT) sintering and Spark Plasma Sintering (SPS). The first composite (marked as BNT), composed of 65 vol% cubic boron nitride (cBN), was sintered from the cBN–TiN–Ti₃SiC₂ system using the HPHT technique at a pressure of 7.7 GPa. The second composite (marked as AZW) was fabricated from the Al₂O₃–ZrO₂–WC system using SPS at a pressure of 63 MPa. The final phase composition of BNT material differed significantly from the initial composition due to reactions occurred during sintering. In contrast, the phase composition of the AZW ceramic composite before and after sintering was similar. The materials exhibited high quality, as evidenced by a Young’s modulus of 580 GPa for BNT and 470 GPa for AZW, along with hardness of 26 GPa for BNT and 21 GPa for AZW. Both composites were used to prepare cutting inserts that were evaluated for their performance in machining Inconel 718 alloy. While both inserts showed durability comparable to their respective reference commercial inserts, they differed in performance and price relative to one another. Full article

This study aims to genomically elucidate six isolates of rapidly growing non-tuberculous mycobacteria (RGM) derived from Siamese fighting fish (Betta splendens). These isolates had previously undergone phenotypic and biochemical characterization, antibiotic susceptibility testing, and in vivo virulence assessment. Initial DNA barcoding using the 16S rRNA sequence assigned these six isolates to five different species, namely Mycobacterium chelonae (BN1983), M. cosmeticum (BN1984 and N041), M. farcinogenes (SNSK5), M. mucogenicum (BN1956), and M. senegalense (BN1985). However, the identification relied solely on the highest percent identity of the 16S rRNA gene, raising concerns about the taxonomic ambiguity of these species. Comprehensive whole genome sequencing (WGS) and extended genomic comparisons using multilocus sequence typing (MLST), average nucleotide identity (ANI), and digital DNA–DNA hybridization (dDDH) led to the reclassification of BN1985 and SNSK5 as M. conceptionense while confirming BN1983 as M. chelonae and BN1984 and N041 as M. cosmeticum. Notably, the analysis of the BN1956 isolate revealed a potential new species that is proposed here as M. mucogenicum subsp. phocaicum sp. nov. Common genes encoding “mycobacterial” virulence proteins, such as PE and PPE family proteins, MCE, and YrbE proteins, were detected in all six isolates. Two species, namely M. chelonae and M. cosmeticum, appear to have horizontally acquired T6SS-II (clpB), catalase (katA), GroEL (groel), and capsule (rmlb) from distantly related environmental bacteria such as Klebsiella sp., Neisseria sp., Clostridium sp., and Streptococcus sp. This study provides the first draft genome sequence of RGM isolates currently circulating in B. splendens and underscores the necessity of WGS for the identification and classification of mycobacterial species. Full article

Tetragonal and hexagonal hybrid sp³/sp² carbon allotropes C₅ were proposed based on crystal chemistry and subsequently used as template structures to identify new binary phases of the B–N system, specifically tetragonal and hexagonal boron nitrides, B₂N₃ and B₃N₃. The ground structures and energy-dependent quantities of the new phases were computed within the framework of quantum density functional theory (DFT). All four new boron nitrides were found to be cohesive and mechanically (elastic constants) stable. Vickers hardness (H_V), evaluated by various models, qualified all new phases as superhard (H_V > 40 GPa). Dynamically, all new boron nitrides were found to be stable from positive phonon frequencies. The electronic band structures revealed mainly conductive behavior due to the presence of π electrons of sp²-like hybrid atoms. Full article

The objective of this study was to evaluate the bait preference of three selected bait types by local dogs and the induced immunogenicity of the oral rabies vaccine strain SPBN GASGAS in Morocco. The vaccine strain, combined with different bait types, has been tested in many different settings, but not yet in northern Africa. Overall, bait consumption and preference were similar in other studies using the same materials (bait type and sachet). The intestine bait had the highest acceptance rate (97.6%, 95%CI: 87.4–99.9), followed by the egg bait (83.0%, 95%CI: 69.2–92.4). Only 52% (95%CI: 37.4–66.3) of the dogs showed an interest in the fish meal bait. However, considering the successful release of the contents of the sachet (blue-dyed water) into the oral cavity, the egg bait (65.7%, 95%CI: 47.8–80.9) scored better than the intestine bait (51.7%, 95%CI: 32.5–70.6). The dogs selected for the immunogenicity study were offered the egg bait containing a sachet filled with SPBN GASGAS (3.0 mL, 10^7.5 FFU/mL) or were given the same dose by direct oral administration (d.o.a.). In addition, several dogs were vaccinated by the parenteral route (s.c.) using a commercially available inactivated rabies vaccine. Unfortunately, due to the COVID-19 pandemic and subsequent travel restrictions, it was not possible to collect blood samples directly after vaccination. The blood samples were collected pre-vaccination and on five occasions between 450 and 1088 days post vaccination. The seroconversion rate, as determined for rabies-virus-neutralizing antibodies by the FAVN test, was significantly lower than that found for binding antibodies, as determined by ELISA, for all blood samples collected post vaccination. No treatment effect (bait, d.o.a., s.c.) could be seen in the seroconversion rate. At 15 months post vaccination, 84.2% of the dogs offered vaccine bait still tested sero-positive in ELISA. Only after 3 years was a clear drop in the seroconversion rate observed in all three treatment groups. This study confirms the long-term immunogenicity of the oral rabies vaccine SPBN GASGAS in dogs under field conditions. Full article

Background: The modulation of cardiac sympathovagal balance alters following acute resistance training (RT) sessions. Nevertheless, the precise influence of RT at varying load intensities on this physiological response remains to be fully elucidated. Therefore, the aim of this study was to compare the time course of recovery following low- (40%), moderate- (60%), and high- (80%) load-intensity RT protocols performed up to muscle repetition failure in resistance-trained men. Method: Sixteen young, resistance-trained men (mean age: 21.6 ± 2.5 years, mean height: 175.7 ± 8.9 cm, mean weight: 77.1 ± 11.3 kg) participated in a randomized crossover experimental design involving three sessions, each taken to the point of muscle failure. These sessions were characterized by different load intensities: low (40% of 1-repetition maximum, 1RM), moderate (60% of 1RM), and high (80% of 1RM). The exercise regimen comprised four exercises—back squat (BS), bench press (BnP), barbell row (BR), and shoulder press (SP)—with each exercise consisting of three sets. Throughout each session, heart rate variability (HRV) and blood pressure (BP) parameters were assessed both pre-exercise and during a 40 min post-exercise period, segmented into 10 min intervals for stabilization. Statistical analysis involved the use of a repeated measures ANOVA. Results: It was observed that the 40% and 60% RT sessions resulted in a significantly higher root mean square of successive R-R intervals (RMSSD) value compared to the 80% RT session in the post-exercise recovery process in 30 min (respectively, p = 0.025; p = 0.028) and 40 min (respectively, p = 0.031; p = 0.046), while the 40% and 60% RT sessions produced similar responses. The 40% RT session was significantly higher in the high frequency (HF) value post-exercise in 40 min compared to the 80% RT session (p = 0.045). Conclusions: Our findings suggest that engaging in resistance training (RT) sessions to muscle failure at an intensity of 80% induces acute increases in sympathetic activity, potentially leading to elevated cardiovascular stress. For individuals with normal blood pressure, it is advisable to opt for lighter loads and higher repetition volumes when prescribing RT, as heavier-load RT may carry an increased risk of cardiac-related factors. Full article

Peat-based substrates have been widely used in greenhouse vegetable production (GVP). However, peat is a non-renewable resource, and there is a problem with N₂O emissions when it is used in greenhouse vegetable production due to the application of large quantities of nutrient solutions. Sphagnum (SP) is a precursor substance and a renewable resource for peat formation, and it has good physical and chemical properties. However, there has been no study on the effect of using sphagnum to replace peat in greenhouse vegetable production on N₂O emissions. Therefore, this study used a peat substrate as the control treatment (CK), with sphagnum replacing peat at 25% (25SP), 50% (50SP), 75% (75SP), and 100% (100SP) in six treatment groups. Moreover, lettuce was used as the experimental subject in potting experiments, and the physicochemical properties, N₂O emissions, N₂O isotope δ value, and N₂O-related microbial activity and community structures were determined using different treatments. Compared with the CK treatment, the 25SP treatment significantly reduced N₂O emissions by 55.35%, while the 75SP treatment significantly increased N₂O emissions by 67.76%. The 25SP treatment reduced N₂O to N₂ to the highest extent and demonstrated the lowest contribution of fungal denitrification (FD) and bacterial nitrification (BN) processes, thereby resulting in lower N₂O emissions. In contrast, NH4+ and NO₃⁻ were the main substrates for N₂O emissions; the 75SP treatment had higher NH₄⁺ and NO₃⁻ contents and a lower relative abundance of the nosZ gene, thereby resulting in higher N₂O emissions. In addition, N₂O production and reduction were dominated by bacterial denitrification for all treatments. Thus, this study analyzed the community composition of denitrifying bacterial genera and their association with physicochemical properties. The results indicated that the dominant denitrifying genus in the peat substrate was Rhodanobacter and that sphagnum replacement reduced the relative abundance of Rhodanobacter. The dominant genus was Massilia at 100% sphagnum replacement. More importantly, Rhodanobacter was correlated with C/N and electrical conductivity (EC), whereas Massilia was affected by NH₄⁺ and the water-filled pore space (WFPS). Therefore, different denitrification-dominant genera were affected by different environmental factors, which indirectly affected N₂O emission. In summary, the 25SP treatment was able to improve nitrogen use efficiency and had no significant effect on lettuce yield. Therefore, 25% sphagnum replacement is the most suitable percentage for peat replacement. Full article

Developing a solid lubricant with the ideal blend of lubrication and mechanical strength poses a formidable challenge. For the first time, we delve into synthesis and wear behavior of multicomponent 2D materials via spark plasma sintering (SPS) by mixing equimolar concentrations of hexagonal boron nitride (hBN), graphene nanoplatelets (GNPs), molybdenum disulfide (MoS₂), and tungsten disulfide (WS₂) using ball-milling (BM) and cryo-milling (CM) techniques. The mixing process controls the distribution of parent phases and thus solid-solutions, forming new phases, namely BCN, (Mo,W)S₂, and B₄C in the sample post sintering. The CM sample revealed a higher densification of 93% in contrast to the BM sample, with only 86% densification and a higher content of BCN, (Mo,W)S₂, and B₄C phases, exhibited via XRD and confocal Raman analysis. CM sample showed improved wear resistance (up to 46%) elicited from the lower wear volume loss (9.78 × 10⁶ µm³) as compared to the BM sample (14.32 × 10⁶ µm³). The dominant wear mechanisms were plowing, cracking, spallation, and severe abrasion in the BM sample, while cracking and plowing in the CM sample. The findings can pave the way for tailoring solid lubricants’ compositions and wear behavior per the intended application. Full article