Search Results (1,666)

Ultrasound-assisted vacuum drying (USVD) has emerged as an increasingly studied food drying approach to overcome mass and energy transfer limitations associated with conventional vacuum drying. This study aims to clarify the behavior of the USVD process by synthesizing findings from product- and condition-specific studies. This review critically examines 38 core USVD studies published between 2014 and 2025, complemented by related comparative research, to assess the effects of USVD on drying efficiency, product quality, and key process parameters across diverse food matrices. The reviewed literature consistently demonstrates that USVD enhances drying kinetics, with increases in drying rate reaching approximately 94%, depending on product characteristics and operating conditions. Due to shorter drying times, USVD also provides potential economic advantages through reduced energy costs, equipment utilization and overall process costs. Furthermore, research has found that USVD retains quality attributes including color and bioactivity of a wide range of foods. USVD-dried products commonly exhibit improved microstructural integrity and enhanced porosity, which imparts superior rehydration. In conclusion, this study highlights the strong potential of USVD to enhance drying efficiency while preserving product quality. Full article

This paper investigates how the thickness of dogbone tensile specimens made from heat-treated Hastelloy-X alloy produced by Laser Powder Bed Fusion (LPBF) influences their mechanical properties and microstructure. The focus of the investigation is on surfaces in an “as-built” condition and considers a range of thickness from 3 to 1 mm. The “as-built” surfaces condition is a fundamental outcome, considering that LPBF technology’s key feature is the ability to produce intricate and complex geometries that are difficult to achieve with conventional manufacturing technologies. The specimens were fabricated according to ASTM E8/E8M-21 and were heat-treated in a vacuum furnace at 1150 °C for two hours. The microstructure of the material was evaluated through porosity, EBSD, and Microhardness analyses. The mechanical properties were evaluated through tensile tests conducted at room temperature on dogbone specimens fabricated both parallel and perpendicular to the building direction. The findings indicate a significant reduction in mechanical properties that could be correlated with the reduction in specimen thickness, reflecting a gradual decline from the baseline. Specifically, a 14% decrease in Ultimate Tensile Strength (from 612 to 528 MPa), an approximately 19% reduction in Young’s Modulus (from 190 GPa to 153 GPa), and a 32% decrease in Elongation at Break (from 59.2% to 40.0%) were observed. Furthermore, it was noted that the printing orientation of the specimens significantly affects their mechanical properties, regardless of thickness. Overall, the results suggest that applying standard heat treatment under specific conditions, such as with a thin, exposed wall of about 1mm with a striped strategy, may not lead to adequate material performance. Full article

Tamarillo (Solanum betaceum) processing is characterized by early biomass exclusion and thermal stabilization, which may limit in-process retention of phytochemicals. This study evaluated an integrated sequence combining Flash Vacuum Expansion (FVE) under different processing conditions with whey protein-based cryostructuring as a strategy to enhance the redistribution and structural immobilization of tamarillo bioactives. FVE promoted migration of phenolics and pigments prior to mechanical fractionation. Selected FVE-treated puree was incorporated into a whey protein matrix and subjected to cryostructuring and freeze-drying to generate a porous stabilization scaffold. Structural characterization by scanning electron microscopy and gas adsorption confirmed the formation of an interconnected porous matrix. Cryostructuring reduced water activity to 0.17 ± 0.01 and produced high porosity (91.9%) with low bulk density (0.109 g·cm⁻³). Total phenolic retention exceeded 83%, while anthocyanins showed greater sensitivity (46% retention). No statistically significant additional losses of phenolics or antioxidant activity were observed during cryostructuring relative to gelation. The integrated approach illustrates a process-level stabilization pathway in which redistributed phytochemicals are physically confined within a porous scaffold, providing a structurally differentiated alternative to conventional drying for improved in-stream resource utilization. Full article

With Aligned Formable Fibre Technology (AFFT^™), fibers are reformatted into highly oriented epoxy prepreg tapes, enabling the structural reuse of recycled composite waste. The present study investigates whether discontinuous fiber laminates produced with AFFT^™ can be characterized and optimized with the same finite-element workflows long established for continuous fiber composites and whether the resulting structures meet demanding stiffness targets. Initially, various manufacturing methods were adopted, including vacuum bagging, compression molding at 7 bar to simulate autoclave conditions, and compression molding at 90 bar, comprising the three most reasonable manufacturing processes for AFFT^™ laminates. Experimentally measured orthotropic properties were introduced into a finite-element model representing an idealized bicycle top tube, which was chosen as a case study. A genetic algorithm screened candidate stacking sequences, minimizing the combined bending-and-torsion deflection. The best lay-ups reduced deformation by more than 30% compared to a quasi-isotropic baseline, showing that well-oriented short fibers can significantly contribute to the stiffness of composites. Tubes produced with the optimized lay-up were tested in three-point bending tests, and the measured stiffness matched simulations within 5%. These results confirm a key point for sustainable engineering: despite the absence of continuous fibers, conventional simulation strategies accurately predict the performance of AFFT^™ laminates and can be used as the basis for effective genetic optimization. This validation is significant: it enables the design of stiff, high-performance structures from recycled materials using established, cost-effective methods. By proving that optimization strategies developed for traditional continuous fiber composites apply to AFFT^™, this study offers a trusted and accessible pathway to scale circular economy solutions in next-generation composite products. Full article

Painho de Porco Preto is a traditional product of the Alentejo region, made with cuts of Alentejano autochthonous breed pigs. The objective of this study was to evaluate how different storage temperatures (4 °C and room temperature (20 ± 2 °C)) could influence the quality and safety of the sliced vacuum-packed Painho de Porco Preto, throughout 6 months of storage. Analyses included physicochemical parameters, microbiological, and sensory analysis. Throughout storage, the product showed low TBARS values (<3 MDA/kg) and stable tocopherol levels under both storage conditions, although the samples at room temperature performed slightly better. a_w and pH values were higher for samples stored at 4 °C, which influenced the results of some parameters. Color coordinate b* had an increase in values by the end of storage for the fat portion of the slices, but the rest of the parameters stayed stable. Nitrate/nitrite contents remained within expected ranges for dry-cured sausages. Microbiological analyses confirmed the absence of major pathogens during the study period, while variations in growth were observed depending on storage temperature. In sum, the results indicate that sliced vacuum-packaged Painho de Porco Preto can maintain acceptable quality and safety for 6 months at room temperature. These findings provide useful information for the meat industry by supporting the optimization of storage strategies and shelf-life management for sliced traditional dry-cured sausages. Full article

Decarburization during austenitization degrades the surface integrity and mechanical performance of tool steels, yet the quantitative influence of process pressure remains unclear. In this study, the effect of process pressure on the decarburization behavior of H13 tool steel was investigated. Specimens were austenitized at 920–1020 °C for 60 min under pressures ranging from 0.01 to 760 Torr. Carbon concentration profiles were measured by electron probe microanalysis, and hardness degradation and mass loss were evaluated. A one-dimensional diffusion model with a Robin boundary condition was applied to describe the coupled effects of carbon diffusion and surface reaction. High-vacuum conditions suppressed decarburization, whereas increasing pressure accelerated carbon loss, leading to deeper decarburized layers and pronounced hardness reduction. The model reproduced the experimental results and revealed a pressure-dependent transition in the dominant decarburization mechanism. Full article

To address the decline in oxygen production capacity and the increase in specific energy consumption of portable vacuum pressure swing adsorption (VPSA) oxygen systems under high-altitude low-pressure conditions, a rotary-valve integrated VPSA numerical model based on a five-bed, ten-step cycle was established in this study and analyzed on the Aspen Adsorption platform. The results show that, under a trade-off between oxygen purity and recovery, an oxygen purity of 93.1% and an oxygen recovery of 27.8% can be achieved when the purge-valve flow coefficient is $6.67\times {10}^{-5}\mathrm{kmol}/(\mathrm{h}·\mathrm{bar})$. When the product-valve flow coefficient is $0.028\mathrm{mol}·{\mathrm{s}}^{-1}·{\mathrm{MPa}}^{-1}$ and the altitude increases from 3000 m to 4500 m, the oxygen production rate decreases by about 22%, while the specific energy consumption increases by about 32.4%. This indicates that the reduction in oxygen partial pressure has a significant effect on the separation driving force. As the product-valve flow coefficient increases from $0.010$ to $0.037\mathrm{mol}·{\mathrm{s}}^{-1}·{\mathrm{MPa}}^{-1}$, the oxygen production rate continuously increases and the specific energy consumption decreases at all altitude conditions. At an altitude of 3000 m, for example, the oxygen production rate increases from $0.12{\mathrm{m}}^3·{\mathrm{h}}^{-1}$ to $0.176{\mathrm{m}}^3·{\mathrm{h}}^{-1}$, while the specific energy consumption decreases from $3.58\mathrm{MJ}·{\mathrm{m}}^{-3}$ to $2.93\mathrm{MJ}·{\mathrm{m}}^{-3}$. The effect of feed flow rate on specific energy consumption shows a trend of first decreasing and then increasing. The minimum energy consumption is obtained in the range of 18–$20\mathrm{L}/\min$. These results provide a theoretical basis for parameter matching and energy-efficiency optimization of multi-bed rotary-valve VPSA systems under high-altitude conditions. Full article

Umbral theory, formulated in its modern version by S. Roman and G. C. Rota, has been reconsidered in more recent times by G. Dattoli and collaborators with the aim of devising a working computational tool in the framework of special function theory. Concepts like the umbral image and umbral vacuum have been introduced as pivotal elements of the discussion which, albeit effective, lack generality. This article is directed towards endowing the formalism with a rigorous formulation within the context of formal power series with complex coefficients $(\mathbb{C}⟦t⟧,\partial )$. The new formulation is founded on the definition of the umbral operator $\mathfrak{u}$ as a functional in the “umbral ground state” subalgebra of analytically convergent formal series $\phi \in \mathbb{C}\left\{t\right\}$. We consider in detail some specific classes of umbral ground states $\phi$ and analyse the conditions for analytic convergence of the corresponding umbral identities, defined as formal series resulting from the action on $\phi$ of operators of the form $f\left(\zeta {\mathfrak{u}}^{\mu }\right)$ with $f\in \mathbb{C}\left\{t\right\}$ and $\mu ,\zeta \in \mathbb{C}$. For these umbral states, we exploit the Gevrey classification of formal power series to establish a connection with the theory of Borel–Laplace resummation, allowing us to make rigorous sense of a large class of—even divergent—umbral identities. As an application of the proposed theoretical framework, we introduce and investigate the properties of new umbral images for the Gaussian trigonometric functions, which emphasise the trigonometric-like nature of these functions and enable defining the concept of a “Gaussian Fourier transform”, a potentially powerful tool for applications. Full article

Fresh bluefin tuna is highly susceptible to quality deterioration during refrigerated storage due to lipid oxidation and microbial activity, creating a need for effective clean-label preservation strategies. This study evaluated the efficacy of natural astaxanthin as an antioxidant treatment to improve the refrigerated stability of fresh bluefin tuna (Thunnus thynnus) fillets stored under vacuum packaging (VP) or modified atmosphere packaging (MAP; 70% N₂/30% CO₂). Tuna fillets were treated by short immersion in astaxanthin solutions (10–20 mg/L), applied alone or in combination with other natural antioxidants, including ascorbic acid, and compared with a rosemary–ascorbic acid reference system. Selected treatments incorporated microencapsulated astaxanthin to enhance antioxidant stability. Quality changes were monitored during refrigerated storage (4 °C) through sensory evaluation (appearance, colour, and odour), total volatile basic nitrogen (TVBN), histamine determination, and microbiological analyses. Astaxanthin-treated samples exhibited improved colour stability, delayed sensory deterioration, and significantly lower TVBN accumulation compared with the rosemary–ascorbic acid reference treatment. Under MAP conditions, astaxanthin reduced TVBN values by approximately 20% after 12 days of storage, while microencapsulated astaxanthin combined with ascorbic acid achieved reductions of up to 30% under vacuum packaging. All selected treatments complied with regulatory microbiological and histamine limits throughout storage. These results indicate that natural astaxanthin, particularly in microencapsulated formulations, can enhance quality stability of fresh bluefin tuna when applied in combination with oxygen-limiting packaging systems under controlled refrigerated conditions. The findings provide a scientific basis for further investigation of astaxanthin-based preservation strategies in high-value seafood products. Full article

Background/Objectives: Post-cesarean section scar niche pregnancy is one of the rarest forms. It is characterized by implantation of the gestation sac within the scar niche and is often associated with chorionic villi adhesion into the thinned cesarean section scar. The increasing incidence of this condition is associated with the increasing frequency of cesarean sections and the widespread use of ultrasound in early pregnancy. The most significant clinical findings are the detection of chorionic villus invasion and uterine wall insufficiency, which may be detected using magnetic resonance imaging, including contrast, and are crucial for determining patient management. This pathology may be considered life-threatening due to complications such as early uterine rupture with bleeding, which, if not diagnosed promptly, can lead to hysterectomy and loss of the woman’s reproductive health. Early diagnosis allows for the use of conservative treatment methods, preserving the uterus. The aim of the study is to clarify the clinical practices to follow in cases where an MRI examination with contrast agent is indicated to be performed on a pregnant patient. Methods: Ultrasound and MRI examination with counter-rotation, as well as histological and immunohistochemical examination of the remnants of the gestational sac were performed. Results: A 36-year-old pregnant woman was hospitalized in her eighth week of pregnancy with complaints of vaginal bleeding and persistent abdominal pain. An ultrasound scan revealed a pregnancy of 8 weeks and 5 days, and a low-lying chorion in the isthmus of the uterus, along with thinning of the cesarean scar and the formation of a scar niche resembling a hernia. Early signs of chorionic invasion were not treated. An MRI revealed signs of superficial chorionic adhesion to the cesarean scar, both to the isthmus and the internal os. Given that the woman did not wish to continue the pregnancy, uterine artery embolization was performed to reduce potential blood loss. Subsequently, laparoscopy, adhesiolysis, vacuum aspiration of the gestational sac, uterine curettage, hysteroresectoscopy, and coagulation of the fetal bed were performed. Histological and immunohistochemical examination revealed signs of inflammation in the area of the suspected lesion. Conclusions: This case report shows the potential value of MRI in complex cases of ultrasound detection of a gestational sac within scar tissue. MRI was used to assess the location of the gestational sac and evaluate the thickness of the cesarean scar to detect its dysfunction. Furthermore, contrast enhancement of the MRI may be useful in the most complex cases but requires an informed consent discussion with the patient. However, the latter issue requires discussion and proof of its safety for the fetus. Full article

As one of the three fundamental modes of heat transfer, thermal radiation has long attracted interest due to its independence from a medium and its strong temperature dependence. In extreme environments such as deep space exploration and cryogenic engineering, thermal radiation often becomes the dominant heat transfer mechanism. Consequently, the radiative properties of materials are crucial for achieving precise thermal control, directly influencing the thermal stability and overall performance of advanced systems, including space probes, cryogenic devices, and superconducting components operating under high-vacuum and low-temperature conditions. This paper provides a systematic review of the physical mechanisms, key factors affecting emissivity, major measurement methods, and technological developments related to material radiative properties at cryogenic temperatures. Particular attention is given to experimental methods and techniques describing material radiative behavior, along with a comparative analysis of the suitability of different measurement techniques for cryogenic applications. Finally, the study highlights the significant practical value of this research for fields such as aerospace, precision electronics, and cryogenic instrumentation, aiming to offer insights for optimizing cryogenic thermal management and guiding the design of novel functional materials. Full article

After approximately 60 years of service, the 2856 MHz LINAC injector, of the Canadian Light Source (CLS), has been retired to make space for a new 3000.24 MHz LINAC injector, the frequency of which is a multiple of the 500.04 MHz CESR-B-type superconductive radio frequency cavity used in the CLS storage ring. The new CLS LINAC injector has been designed and built by RI Research Instruments GmbH. The design is based on their robust S-band RF traveling-wave accelerating structures technology already serving other laboratories in the USA, Australia, Taiwan, Switzerland, and Sweden. In order to reduce cost and optimize space, the CLS has replaced its six accelerating RF structures, each 3.05 m long, delivering a 250 MeV electron beam with three 5.26 m long accelerating structures that will deliver the same beam energy. In order to do so, one RF structure is powered by one klystron modulator, and the last two RF structures receive their RF power from a second klystron modulator that passes through a SLED system. The SLED system multiplies the peak power by a factor of 5 to 6 and is then equally split to power each structure. We are reporting on the issues encountered during the commissioning of this new injector, on how we have tackled them and where the injector, compared to its technical specification, is standing today. Full article

To address pressure-drop-induced safety risks in high-drop gravity-fed irrigation pipelines, this study investigates coordinated prevention and control strategies that integrate air release and vacuum valve groups with flow-adaptive valve closure rules. A large-scale self-pressurized irrigation network (1.33 × 10⁸ m²) in Karamay, Xinjiang, China, is selected as a representative case study. Based on one-dimensional transient flow modeling, pressure drop and negative-pressure characteristics induced by inlet valve closure in the main pipeline are analyzed using wave speed theory, governing differential equations, and the finite difference method. A coordinated protection framework is proposed that explicitly links valve operating patterns with the spatial configuration of protective devices. Unlike conventional schemes that rely on empirical layouts and fixed closure rules, this study introduces a critical-flow-velocity-based valve grouping method combined with flow-dependent valve closure strategies. Simulation results demonstrate that a strategically optimized configuration of air release and vacuum valves along the main pipeline is sufficient to eliminate negative pressure under all operating conditions. For flow rates below 6 m³/s, linear valve closure ensures safe operation, whereas a two-stage closure is required for higher flow rates (6–10 m³/s). As flow increases, reducing the fast-closure ratio and extending the total closure time effectively suppress pressure-drop-dominated transient effects at vulnerable inlet sections. By effectively mitigating transient pressure surges, the proposed coordinated “valve closure-protection device” strategy improves system adaptability to flow variability and provides practical engineering guidance for the safe operation of gravity irrigation systems, particularly high-gradient self-pressurized networks. Full article

Ti₃C₂T_x/Al6061 composites were fabricated via vacuum induction melting, with systematic analysis conducted on their microstructure, mechanical properties, and wear behavior. Findings indicate that Ti₃C₂T_x addition significantly refined the composite grain size. Uniformly dispersed Ti₃C₂T_x particles promoted heterogeneous nucleation, reducing the average grain size by 44.7% compared to the matrix at the optimal 2 wt.% addition. Strong interfacial bonding ensured efficient load transfer, resulting in a 48.4% increase in tensile strength for the 2 wt.% Ti₃C₂T_x/Al6061 composites compared to the matrix alloy, while elongation decreased by 11.7%. Tribological analysis revealed that the wear rate of 2 wt.% Ti₃C₂T_x/Al6061 composites increases with applied load but remained substantially lower than Al6061 under all tested conditions. This excellent wear resistance is attributed to the synergistic effect of the protective mechanically mixed-layers formation and the inherent self-lubrication property of Ti₃C₂T_x during sliding contact. With increasing load, the friction coefficient and tendency for microcracking on the worn surface of the composite increased, and the dominant wear mechanisms transitioned from abrasive and adhesive wear to delamination wear. Full article

The structural segmentation of wind turbine blades offers advantages in transportation, manufacturing, and maintenance; however, it introduces interfaces that may compromise load transfer and fatigue performance. This study presents the experimental and numerical validation of a composite coupling system designed for small wind turbine blades compliant with IEC 61400-2 requirements. A 2 m representative section extracted from the mid-span region of a 9 m blade was manufactured using vacuum-assisted resin infusion and tested under static loading conditions. A detailed finite element model based on classical laminate theory and orthotropic material properties was developed to predict structural response. Experimental measurements showed a maximum tip deflection of 15 mm under the applied load, compared to 13.76 mm predicted numerically, corresponding to a deviation of 8.9%. Surface strain measurements obtained from eight strain gauges installed across the blade–coupling interface indicated maximum mean values of +632.4 με in tension and −664.2 με in compression, with no evidence of localized strain amplification at the instrumented locations. These findings demonstrate that fully composite permanent segmentation can preserve stiffness continuity while maintaining strain levels below reported fatigue initiation thresholds, supporting the structural feasibility of segmented blade architectures for small wind turbine applications. Full article