Search Results (3,219)

Fused deposition modeling (FDM)-based three-dimensional (3D) fabrication offers a viable approach to manufacturing highly customized carbon fiber-reinforced polyether ether ketone (CFR-PEEK) components with complex geometries. However, the mechanical properties and surface roughness of FDM-fabricated parts are strongly influenced by processing parameters, particularly layer thickness. This study investigates the influence of layer thickness (0.1 mm and 0.2 mm) on the surface roughness, crystallinity, mechanical properties, and morphological characteristics of FDM-printed 10% CFR-PEEK specimens. The specimens were characterized using mechanical testing, differential scanning calorimetry (DSC), confocal laser microscopy, X-ray micro-computed tomography (µCT), and scanning electron microscopy (SEM). The results show that specimens printed with a 0.2 mm layer thickness exhibit higher crystallinity and ball indentation hardness while also showing increased surface roughness and porosity, with µCT analysis revealing larger and more spatially clustered voids near the sub-perimeter regions. In contrast, specimens printed with a 0.1 mm layer thickness demonstrate higher tensile strength, elastic modulus, elongation at break, and compressive stress. SEM fractography further indicates improved interlayer bonding and a relatively cohesive fracture surface in specimens printed with a 0.1 mm layer thickness. These findings demonstrate clear layer-thickness-dependent processing–structure–property relationships in FDM-printed CFR-PEEK composites and provide guidance for optimizing printing parameters to achieve improved mechanical performance. Full article

The effect of cold smoking on the physicochemical, microbiological, and aromatic properties of Formaella-type cheese has not been previously investigated. In this study, experimental Formaella-type hard cheeses (≤38% moisture) were produced using a multistep high-temperature cooking process and subjected to weak (20 min) and intense (60 min) cold smoking, alongside an unsmoked control. Cheeses were analyzed before and after smoking and during refrigerated storage (up to 90 days). Smoking significantly influenced pH, water activity, and colour parameters, with intensively smoked cheeses exhibiting lower pH, reduced lightness (L*), and increased redness (a*) and yellowness (b*). Microbiological analyses revealed low viable counts across all samples, attributed to severe cooking steps and vacuum storage. Smoking, particularly at high intensity, significantly reduced total mesophilic counts and enterococci, while Enterobacteriaceae, staphylococci, yeasts, and moulds were not detected after manufacture. The dominant microbiota consisted mainly of lactic acid bacteria, identified by MALDI-TOF MS, including Enterococcus durans, Ent. faecium, Leuconostoc lactis, Leuconostoc mesenteroides, Streptococcus thermophilus, Lacticaseibacillus rhamnosus, and Lactobacillus curvatus. Headspace-SPME-GC-MS analysis identified 75 volatile compounds, with free fatty acids, ketones, aldehydes, and lactones as the predominant groups. Smoking introduced characteristic phenolic and furan derivatives associated with smoky aroma. Overall, smoking intensity modulated microbial dynamics and aroma development without compromising microbiological quality. Full article

A capacitive micromachined ultrasonic transducer (CMUT) was engineered and functionalized with either zeolitic imidazolate framework-8 (ZIF-8) dispersed in an AZ1512HS photoresist matrix or with graphene oxide (GOx) to operate as a gravimetric sensor for organic vapors. The sensor response was investigated under controlled humidity conditions during pulsed exposure to acetone, ethyl methyl ketone, isopropanol, kerosene, and diesel vapors. The impedance of the device was monitored by observing and tracking the resonance frequency shift as well as the resistance maximum shift, giving us the possibility to track two response parameters simultaneously. Different combinations of shifts in the sensor resonance frequency and the resistance maximum values were observed for the ZIF-8 functionalized device when exposed to the selected vapors, ranging from 12.4 kHz for ethyl methyl ketone to 2.4 kHz for diesel, and from 580 Ω for acetone to 20 Ω for isopropanol. Sensors functionalized with GOx did not demonstrate any significant response to either ethyl methyl ketone or isopropanol in the frequency domain. GOx-functionalized sensors were used for relative humidity monitoring in test gases. Besides the conventional response of the produced gravimetric sensing system, we also observed a strong relationship between the humidity of the gas mixture and the strength of the interaction of target gases with the functional film of the sensor. The results highlight the multidimensional nature of the sensor response and demonstrate how humidity influences the interaction between vapor molecules and the functional coating. This paper focuses on the characterization of the coupled behavior of resonance frequency and resistance shifts under controlled operating conditions. The presented experimental setup provides a basis for future concentration-dependent investigations and functional material comparisons in CMUT-based gravimetric sensing systems and provides a necessary foundation for accurate interpretation of future concentration-resolved measurements. Full article

Artisanal cheese quality relies on a complex microbiota. The generalized use of commercial starter cultures has been associated with reduced microbial diversity, fueling interest in using indigenous lactic acid bacteria (LAB) as adjunct cultures. This study aimed to evaluate Ligilactobacillus salivarius SP36 as a starter or adjunct culture in ripened cheeses. Culture-based and culture-independent analyses were performed, together with the assessment of some physico-chemical parameters (pH, water activity, and color), including the profile of volatile compounds. All cheeses were microbiologically safe according to current EU legislation. The pH of the cheese made only with the SP36 strain was higher than those of the cheeses manufactured with a commercial starter (with or without strain SP36). L. salivarius SP36 modulated the aroma profile by increasing ethyl esters, alcohols, ketones, organic acids and sulphur compounds. LAB dominated all cheeses, with the highest microbial diversity in the cheese produced without the commercial starter. Lactiplantibacillus plantarum and Lacticaseibacillus paracasei isolates were obtained from all cheeses. Overall, L. salivarius SP36 seems a promising adjunct for mature cheeses, while autochthonous L. plantarum and L. paracasei isolates represent promising candidates for starter or adjunct cultures. Full article

The growing demand for clean-label food ingredients drives interest in novel marine flavorings. This study evaluated the physicochemical, antioxidant, volatile (GC-MS), and sensory profiles of freeze-dried powders from blue crab roe (Callinectes sapidus), sea urchin roe (Paracentrotus lividus), and beluga caviar (Huso huso) to assess their culinary potential. Results revealed that sensory quality is governed by the synergy between a matrix’s lipid composition and endogenous antioxidant capacity. Sea urchin powder, possessing a low polyunsaturated fatty acid (PUFA) profile and high carotenoid content, exhibited exceptional oxidative stability, yielding a concentrated marine aldehyde signature and top consumer scores. Blue crab roe demonstrated a robust PUFA matrix buffered by high phenolic content, facilitating controlled lipid peroxidation into desirable savory volatiles (ketones and aldehydes). Conversely, the high-fat, monounsaturated-dominant beluga caviar lacked sufficient antioxidants, leading to lipid degradation, oxidized hydrocarbons, earthy off-flavors, and poor texture. Both crab and caviar powders exhibited favorable Atherosclerosis and Thrombogenicity indices. Ultimately, balancing lipid composition and endogenous antioxidants is crucial for flavor stability, highlighting the commercial and environmental potential of transforming underutilized or invasive species like blue crab into stable, nutrient-dense marine flavoring agents. Full article

Using alternative energy sources for animal feed, such as hybrid corn varieties rather than genetically modified ones, is important. Therefore, the objective of this work was to assess the effects of supplementation at the end of gestation with Mexican Puma hybrid corn grain on productive and behavioral parameters in sheep. Twenty Columbia multiparous ewes were used; along with their diet, they were provided 600 g/animal/day of cracked corn during the last 20 days of pregnancy and the first week of lactation. The animals were divided into two groups: one fed commercial cracked corn (n = 11) and the other Mexican Tlaoli Puma hybrid cracked corn (n = 9). The productive parameters evaluated in the mother were: body weight, body condition score (BCS), feed intake, weight change, glucose, and ketone body levels, as well as the estimated quality of milk using Brix refractometer values on days 15 and 30 of lactation. In lambs, their rectal and external temperature was measured 2 h after birth, while their weight was measured 2 h after birth and every week until week 6 postpartum. Behavioral parameters were measured in the first two hours postpartum, including the maternal latency of cleaning the offspring, duration of the first cleaning episode, the lamb’s latencies of standing and nursing, and vocalizations in mother and lamb. Weight, BCS and weight change were not affected by the group but were affected by time; these parameters increased at the end of gestation and decreased significantly after delivery (p < 0.05). Ketone body levels were not affected by group or time (p > 0.05) and remained at low values. Glucose levels were not affected by the group but were affected by time; they increased significantly after birth (p < 0.05). Feed intake was similar in both groups (p > 0.05) and decreased as parturition approached (p < 0.05). The estimated milk quality was not affected by the group, nor by the time (p > 0.05). Mothers in both groups began cleaning their offspring within the first three minutes after giving birth and emitted a similar frequency of vocalizations (p > 0.05). However, mothers in the commercial maize group had a longer cleaning episode than those in the hybrid maize group (p < 0.05). The lambs in both groups stood up within the first half hour of birth, suckled before one hour after birth and emitted a similar number of vocalizations (p > 0.05). Temperatures and lamb weight were similar in both groups (p > 0.05); however, lamb weight increased as they aged (p < 0.05). It is concluded that supplementing sheep at the end of gestation with Puma hybrid Mexican corn grain can yield similar productive and behavioral benefits as supplementing with commercial grain. Full article

Rapid expansion of the plant-based milk market has increased the need to understand how the aroma profiles of these alternatives differ from that of dairy milk and how raw material selection and processing influence volatile formation. This study compared the volatile profiles of dairy milk, commercial plant-based milks, and laboratory-prepared cereal and pseudocereal milk prototypes to identify promising materials for plant-based milk development. Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) combined with chemometric analysis was used to characterize volatile compounds in bovine milk, four commercial plant milks, and five laboratory-prepared plant milks. Dairy milk was characterized by fatty acids, esters, and other lipid-derived volatiles, whereas plant-based samples were associated with hydrocarbons, pyrazines, ketones, and phenols. Within the plant-based group, volatile differences were influenced by raw material type and processing history. Commercial products showed more evident processing-related features, whereas laboratory-prepared cereal samples exhibited a simpler volatile background. Among them, barley milk displayed a distinctive toasted and cereal-like signature. Overall, the selected cereal and pseudocereal matrices showed distinct volatile characteristics, as well as relatively uniform raw material backgrounds, implying greater flexibility in aroma expression. These features make them promising candidates for dairy alternatives and may help guide future plant-based milk formulation. Full article

Temperature is a major determinant of plant metabolic plasticity, yet its role in directing volatile and semi-volatile specialized metabolism in Ginkgo biloba remains poorly understood. In this study, we investigated how contrasting low- and high-temperature treatments reshape secondary metabolite contents in G. biloba microclones cultivated in vitro. Plants were exposed to cold (+3 °C) and heat (+30 °C) conditions, and their responses were analyzed using GC–MS profiling, anatomical measurements, chlorophyll fluorescence, and multivariate statistics. Cold treatment selectively increased the abundances of monoterpenes (13.22%) and sesquiterpenes (13.83%), with the strongest accumulation of caryophyllene, eucalyptol, and (1S)-camphor. In contrast, heat treatment reduced ester content to 3.73% and strongly enriched oxy-sesquiterpenes (46.50%) and lactone/ketone/spiroketone (29.54%) contents. The enhanced accumulation of isocalamendiol, isoshyobunone, cyclohexanone derivative, dehydroxy-isocalamendiol, and (+)-2-bornanone was observed under heat. According to the multivariate analysis, control plants were associated with traits reflecting optimal physiological performance, including greater parenchyma, phloem, and xylem thickness, larger vascular bundles, longer stomata, and higher NPQ, qN, Y(NPQ), and F_v/F_m. Cold-treated plants showed thicker epidermis and sclerenchyma, higher stomatal density and width, elevated Y(NO), and an enrichment of esters and terpenoids, whereas heat-treated plants were characterized by thicker adaxial and abaxial epidermis, increased mesophyll thickness, and higher levels of oxygenated metabolites. These findings expand current knowledge beyond terpene trilactones and flavonoids and identify Ginkgo microclones as a useful in vitro model for temperature-guided metabolic reprogramming and targeted metabolite enrichment. Full article

A high-fat (HF) diet disrupts metabolic homeostasis and impairs peripheral circadian rhythms in key metabolic tissues. β-Hydroxybutyrate (BHB), a major circulating ketone body, functions not only as an energy substrate but also as a signaling metabolite regulating nutrient-sensing and inflammatory pathways. However, its role in modulating metabolic–circadian interactions under conditions of nutrient excess remains unclear. In this study, we investigated whether BHB supplementation influences metabolic signaling and circadian clock oscillations in liver, skeletal muscle and adipose tissue under chow and HF conditions. Male C57BL/6 mice were fed chow or HF with or without BHB supplementation (500 mg/kg body weight in the diet) for 7 weeks. Metabolic parameters were assessed by indirect calorimetry, and tissues were collected every 4 h across the circadian cycle. HF feeding increased body weight and adiposity (p < 0.01), reduced AMPK activation, enhanced AKT/mTOR signaling, elevated NF-κB levels and dampened clock gene rhythmicity. BHB supplementation significantly decreased food intake in HF-fed mice (p < 0.01) and partially reversed several molecular alterations in a tissue-specific manner. In skeletal muscle and adipose tissue, BHB increased AMPK activation and reduced mTOR and NF-κB signaling (p < 0.05), whereas hepatic effects were more modest. Notably, BHB modulated circadian gene expression, restoring aspects of rhythmic amplitude and/or phase, particularly in adipose tissue. These findings may indicate that BHB supplementation modulates nutrient-sensing pathways and partially restores peripheral circadian rhythms under HF conditions. While some effects may be influenced by reduced energy intake, BHB may serve as a metabolic signal linking nutrient status to circadian regulation. Full article

MXene, as a suitable and alternative 2D nanofiller incorporated into a proton exchange membrane (PEM), has recently received considerable attention because of desired mechanical stability, promising conductivity, and active surface functional groups. However, agglomeration or sedimentation in PEMs, as well as the water retention capacity under low humidity of MXene, are limiting factors in the field of PEMs. In this paper, modified MXene and TiO₂ nanoparticles used as functional nanofillers were incorporated into sulfonated poly (ether ether ketone) (SPEEK) to prepare novel SPEEK-based composite PEMs. The effects of the nanofiller contents on self-humidifying and protonic conductivity of the composite PEMs were also investigated under different temperatures. When the contents of functionalized MXene and modified TiO₂ are 5 wt.%, proton conductivity, water uptake and methanol permeability of the composite PEMs can be up to 0.143 S/cm, 60% and 2.27 × 10⁻⁷ cm²/s, respectively, which represent increases of about 192%, about 38% and a decrease of 47%, respectively, compared with that of primary SPEEK PEM. Under the synergistic action of functionalized MXene providing a higher number of exchangeable proton sites, modified TiO₂ with inherent hydrophilicity enhancing water retention and Pt providing catalytic sites for the H₂/O₂ reaction to generate water in situ, the self-humidifying capability and proton conductivity of the composite PEMs were improved significantly. Full article

Objectives: This study aimed to compare the retention and fit precision of removable partial denture circumferential clasps fabricated from cast cobalt–chromium, 3D-printed cobalt–chromium, and polyether ether ketone. Methods: A maxillary right first premolar abutment was prepared. Eighty circumferential clasps were allocated into three material groups: cast Co–Cr (n = 20), 3D-printed Co–Cr (n = 20), and PEEK (n = 40). The terminal third of metal retentive clasps was designed to engage 0.25 mm and 0.50 mm undercuts. PEEK clasps were fabricated with two designs: partial (two-thirds) and full-arm undercut engagement. Each group was examined for retentive forces after 1440 cycles (simulating 1 year). Initial and final retentive forces were recorded. Clasp deformation was assessed by measuring inter-arm distance before and after cycling using digital photography and ImageJ software. Results: All clasp groups demonstrated a statistically significant reduction in retention after 1440 cycles (p < 0.05). At both undercut depths, cast and 3D-printed Co–Cr clasps exhibited significantly higher retentive forces than PEEK (p < 0.001). Within the PEEK group, full-arm engagement showed significantly higher retention than partial engagement at the 0.25 mm undercut (p < 0.001), whereas no significant difference was observed between designs at the 0.50 mm undercut (p = 0.406). Fit precision revealed a significant increase in inter-arm distance after cycling (p < 0.05). PEEK clasps exhibited significantly smaller dimensional changes than Co–Cr clasps (p < 0.02). Conclusions: Clasp material, undercut depth, and design significantly influenced retention and fit precision. Co–Cr clasps maintained higher retentive forces, whereas PEEK clasps demonstrated reduced deformation after cycling. Full article

Chickpea flour represents a valuable plant-based ingredient due to its high protein and fiber content; however, its application is limited by antinutritional factors and off-flavor compounds. Fermentation with LAB and yeasts, applied individually or in consortia, resulted in significant microbiological, nutritional, and aromatic changes. The fastest acidification (pH 3.9) and the most effective control of Enterobacteriaceae (<4 log CFU/g after 48 h) were observed in samples containing Lactiplantibacillus plantarum LP23, both as a monoculture and in combination with Debaryomyces hansenii Y15A. Peptide content significantly increased in all fermented samples compared to the control, with a synergistic effect in the co-culture Yarrowia lipolytica Y3 + Lacticaseibacillus paracasei L (around 230%). A pronounced reduction in raffinose-family oligosaccharides was observed, especially in the consortia Y. lipolytica Y3 + Lcb. paracasei L and D. hansenii Y15A + Lacp. plantarum LP23 (0.11–0.16 mmol/100 g). Samples with lower total volatile levels showed higher olfactory acceptability due to a marked reduction in aldehydes (up to 70–95% vs. control), and a balanced accumulation of alcohols, esters, ketones, and organic acids. Overall, LAB–yeast consortia effectively enhanced the nutritional quality, safety, and sensory properties of chickpea flour, supporting its use as a functional ingredient in plant-based foods. Full article

Solvent-free, continuous manufacture of carbon-fiber/poly(ether ether ketone) (CF/PEEK) towpregs via fluidized-bed powder coating requires stable powder fluidization together with controllable coating residence time. A laboratory-scale continuous coating line comprising a creel, guiding/tension rollers, a vibrated fluidized-bed coater, as well as a take-up unit was designed and commissioned. Subsequently, a two-stage optimization and modeling framework was developed. First, PEEK powder fluidization was optimized using a Taguchi L9 design, varying air pressure ($P$), powder weight ($W$), and vibration frequency ($f$); bed expansion ratio ($\epsilon$) and average surface bubble diameter ${(D}_b)$ were measured and ANOVA identified air pressure as the primary contributor to $\epsilon$ (83.4%), establishing a stable operating window. Second, within this window, coating performance was assessed by varying line speed ($V_{line}$) and coating-roller position ($H_r$) in 12 runs and combining them into a geometry-based residence time ($R_t$) for simplified control. Coating quality was quantified based on fiber volume fraction ($Vf$) and composite tensile strength (${\mathsf{\sigma }}_c$) after consolidation. The best condition in the tested range was $Hr=0.5 \mathrm{c}\mathrm{m}$ and $V_{line}=1.5 \mathrm{m}/\mathrm{m}\mathrm{i}\mathrm{n}$ ($R_t=0.54 \mathrm{s}$), achieving 61.5% $Vf$ and 1800.5 MPa tensile strength. The resulting mathematical models predicted $Vf$ and ${\mathsf{\sigma }}_c$ with good accuracy ($R^2\ge 0.92$), supporting parameter selection and process optimization for continuous CF/PEEK towpreg production. Full article

The valorization of agro-industrial byproducts through pyrolysis represents a sustainable route for generating multifunctional raw materials within the framework of a circular bioeconomy. In this study, rice husk (RH) and sugarcane bagasse (SCB) were pyrolyzed in a semi-continuous reactor at 500 °C in order to compare product yields and to characterize resulting gas, aqueous and tar fractions. SCB produced the highest bio-oil yield (44.2 wt%), whereas RH generated the highest char yield (42.9 wt%), consistent with its higher ash and lignin contents. In both cases, tar represented about 12 wt% of the bio-oil. Detailed characterization revealed that the liquid products contained oxygenated compounds of interest, mainly carboxylic acids, ketones, and phenols. Acetic acid was the predominant compound in the aqueous phases, while tars were composed mainly of phenols, ketones, furans, and acids. Particularly, phenols accounted for 52.6% and 37.8% of the total chromatographic area in RH and SCB tars, respectively, whereas ketones represented about 10% in both cases. These results show that pyrolysis of agro-industrial residues not only enables energy recovery but also provides liquid fractions enriched in value-added chemicals. Full article

The homogeneous nature of L-proline organocatalysts restricts their application in aldol condensation due to poor recyclability and stability. Herein, L-proline was heterogenized by ionic intercalation into Mg–Al layered double hydroxides (LDHs), yielding a series of proline-intercalated catalysts with tunable layer structures. Co-precipitation and memory-effect reconstruction strategies were employed to regulate interlayer spacing and proline loading. The resulting catalysts exhibited efficient performance in the aldol condensation of furfural with ketones under mild conditions. The reconstructed catalyst re-Mg₄Al₁P achieved a furfural conversion of 88.67% and a total product yield of 85.54% at room temperature, with product selectivity exceeding 95%. Structural characterizations confirmed that proline was stabilized within the LDH interlayers via R–COO—Mg electrostatic interaction while preserving the secondary amine active site. Mechanistic analysis indicated that the reaction proceeded through enamine- or enol-mediated pathways depending on water content, while the layered LDH framework imposed geometric confinement that suppressed side reactions. Catalyst deactivation in aqueous systems was mainly attributed to proline leaching rather than structural collapse. Full article