Search Results (766)

Diseases caused by pathogenic microorganisms in Bombyx mori have long been a major constraint on the sustainable development of sericulture. Current preventive strategies remain substantially constrained by issues of drug resistance and environmental compatibility. In recent years, the application of nanomaterials for pathogenic microorganism control has garnered escalating attention. Among these, chitosan–silver nanoparticles (CS-Ag NPs), as an emerging class of nanocomposites, integrate the biocompatibility and biodegradability of chitosan with the robust antimicrobial activity of silver nanoparticles, thereby exhibiting considerable potential for preventing pathogenic infections. Nevertheless, the efficacy of CS-Ag NPs against B. mori pathogens has not previously been documented. In this study, CS-Ag NPs were successfully synthesized via chemical reduction. Their antiviral activity was validated using quantitative PCR. The inhibitory efficacy of CS-Ag NPs against Bacillus bombysepticus and Serratia marcescens was evaluated through in vitro inhibition zone assays and bacterial growth curve analysis, with the minimum inhibitory (MIC) concentration for both pathogens determined. Notably, CS-Ag NPs exhibited no significant inhibitory effect on filamentous fungi, potentially due to the impaired ability of nanoparticles to penetrate fungal cell walls. Preliminary mechanistic investigations into the antimicrobial mechanism of CS-Ag NPs were conducted from the perspectives of oxidative stress. Our data showed that CS-Ag NPs could effectively alleviate ROS accumulation induced by the pathogen. In summary, our work systematically investigates the potential of CS-Ag NPs in controlling pathogens and enables the preliminary elucidation of their antibacterial mechanisms. These findings establish a theoretical foundation for the development of pharmaceuticals against pathogenic microorganisms and also offer novel insights into the ecofriendly management of diseases. Full article

Background/Objectives: Implant-associated infections remain among the most severe and clinically challenging complications in contemporary orthopedics, largely due to the formation of persistent bacterial biofilms and the limited penetration of systemically administered antibiotics into the tissue–implant interface. In this context, local antibacterial functionalization of implantable materials represents a promising strategy for the prevention of early infectious complications. The objective of this study was to develop and comparatively evaluate the antimicrobial performance of PLA-based composites loaded with antibiotics from different pharmacological classes, with a view toward their potential application in individualized 3D-printed implants. Methods: Polylactic acid (PLA)-based composites incorporating gentamicin, ciprofloxacin, doxycycline, and vancomycin were fabricated using thermal processing under conditions compatible with extrusion and fused filament fabrication. Physicochemical characterization (FTIR, TGA, SEM) was performed to assess the structure and morphology of the composites, and in vitro antibiotic release studies were conducted. Antimicrobial activity was evaluated using an agar diffusion assay against ATCC reference strains and clinical isolates of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa (n = 10 per species). The antibacterial performance of the composites was evaluated in comparison with standard commercial antibiotic disks used as qualitative reference controls. Results: Antibiotic-loaded PLA composites exhibited consistent and reproducible antibacterial activity, markedly exceeding that of neat PLA. The broadest activity spectrum was observed for PLA–ciprofloxacin (≈29–36 mm) and PLA–gentamicin (≈25–27 mm), which effectively inhibited both Gram-positive and Gram-negative clinical isolates, including MRSA and P. aeruginosa. PLA–vancomycin retained selective activity against staphylococci (≈14–15 mm), whereas PLA–doxycycline demonstrated limited efficacy against Gram-negative pathogens. Physicochemical analysis confirmed successful incorporation of antibiotics without detectable degradation of the polymer structure, while release studies demonstrated sustained antibiotic release from the composite materials. Importantly, the expected pharmacological activity profiles of the antibiotics were preserved after incorporation into the polymer matrix and subsequent high-temperature processing. Conclusions: The results demonstrate the feasibility of integrating clinically relevant antibiotics into a thermoplastic PLA matrix while preserving their selective antimicrobial activity following processing compatible with extrusion and additive manufacturing. The proposed PLA-based composites can be regarded as elements of a pharmacologically tunable antibacterial platform, offering a rationale for the development of context-dependent, biodegradable, 3D-printed implants for the local prevention of implant-associated infections in the setting of increasing antimicrobial resistance. Full article

This study evaluates the mechanical and thermal properties of bricks made from polylactic acid (PLA) and recycled polyethylene terephthalate (rPET). A filament-based 3D printer was used with process parameters specific to PLA, while rPET—also known as recycled plastic—was obtained by grinding and compacting products. Brick samples of various dimensions were manufactured to conduct flexural, compressive, and tensile tests. Several samples were used for each test. On the other hand, a thermal conductivity analysis was performed to determine the internal temperature of dwellings, such as a house or a building. Thermal conductivity influences energy efficiency and the thermal comfort of occupants. The macrostructures observed in the NIKON microscope were examined, where the direction of the fibers and their compaction, which significantly influences thermal conductivity, can be seen. A 53.4% reduction in thermal conductivity was determined for the PLA brick compared to the commercial brick, while the rPET brick showed a 6.4% decrease. The evaluation of the tests carried out on the universal testing machine indicates that the brick made from rPET exhibits a higher maximum load and stress compared to the brick made from PLA in all tests. These results suggest that both the manufacturing process and the composition of the material have a significant impact on the mechanical and thermal properties of plastic bricks. In the flexural test, the recycled plastic brick withstood a maximum stress of 16 MPa and a maximum load of 5784 N. Similarly, in the compression test, the recycled plastic brick withstood a maximum load of 9471 N and a maximum stress of 5.83 MPa. During the tensile test, the rPET brick demonstrated a maximum load of 9203.92 N and a maximum stress of 5.64 MPa. These results show that bricks made from recycled plastic have better mechanical properties compared to polylactic acid bricks in the tests carried out and can therefore be considered for use in the construction industry. Full article

Material extrusion (MEX) additive manufacturing can produce material-dependent variations in dimensional fidelity, internal structure, and deposition stability, even under identical processing conditions. In this study, a comprehensive experimental investigation is conducted on MEX-printed specimens manufactured from a broad set of PLA-based composite materials to quantify these variations and assess their mutual interdependence. Dimensional behavior, internal structural characteristics, and process behavior were systematically investigated using complementary geometric, physical, and deposition-related descriptors. All properties were determined from replicated specimens to ensure statistical robustness, and the resulting datasets were examined using both conventional metrics and multivariate 3D correlation approaches. Compact PLA-based formulations exhibit consistent internal packing, characterized by relative density (RD) values of approximately 0.40–0.46, porosity (ϕ) levels around 55–60%, reduced (≤0.15%) density variability (CV), and small (−0.4–0.0%) volumetric deviations (ΔV). These features reflect stable extrusion and predictable dimensional response. In contrast, foamed, fiber-reinforced, and organic-filled composites display reduced internal packing (RD < 0.40), increased ϕ (>60%), elevated CV (0.27–0.58%), and systematically larger positive ΔV (up to +1.4%), indicating a higher sensitivity to process-induced heterogeneity. Multivariate correlations further reveal that volumetric dimensional distortion is jointly governed by internal packing efficiency and extrusion stability. Overall, the results demonstrate that dimensional accuracy in MEX of PLA-based composites arises from coupled structure–process interactions rather than isolated material or process parameters. The experimental framework proposed here provides quantitative guidance for material selection and process optimization aimed at enhancing geometric fidelity in composite filament fabrication. Full article

Batch production of nanomaterials is highly desired for developing commercial nanoproducts. Here, a brand-new electrospinning method, termed hole electrospinning, was developed for batch production of drug-loaded polymeric nanofibers. Using resveratrol and polyvinylpyrrolidone as model drug and filament-forming matrix, respectively, both hole and single-needle electrospinning were conducted. The resultant nanofibrous films were compared in terms of morphology, physical and thermal properties, mechanical performance, fast-dissolution rate, and antioxidant activity. Analytical and characterization results verified that nanofibers from different processes showed no significant differences in morphology, diameter, porosity, tensile strength, amorphous state, fast-dissolution performance and antioxidant activity. However, hole electrospinning provided 13.3-fold higher productivity than single-needle electrospinning, better drug encapsulation efficiency (97.3 ± 4.5% versus 83.7 ± 6.1%), and higher energy efficiency (0.0393 W/g versus 0.1247 W/g). Based on the protocols reported here, not only was a batch nano-conversion method for polymeric engineering developed, but also an attractive approach for the large-scale production of various complex configurations was proposed for potential commercial nanostructure-based products. Full article

Here, the resistive switching characteristics in a Cu/a-SiC/P+-Si sandwiched structure are systematically investigated for multilevel nonvolatile memory applications. The formation of Cu conducting filaments is believed to be the switching mechanism through temperature-dependent testing. Four distinguished resistance states can be achieved in the Cu/a-SiC/P+-Si memory device through the modulation of suitable compliance current, which could be attributed to the formation of more conductive filaments when applying a higher compliance current during the Set process. In addition, these different resistance values can be easily distinguished and show reliable retention (~105 s), with the temperature even reaching 85 °C, which offers considerable potential for high-density RRAM applications. Full article

Nowadays, synthetic textiles, widely used on the market and largely composed of polyester (polyethylene terephthalate, PET), release microplastic fiber fragments (MPFFs) into the environment, inducing repercussions on ecosystems and health. Reducing these emissions by understanding manufacturing’s influence on MPFF release represents an important challenge for sustainable textile manufacturing and eco-design. This study aims to identify key weaving process factors influencing MPFF release during the first wash, which ends up in wastewater. Employing a Taguchi design of experiments, 18 fabrics were produced on industrial machines from polyester filaments, with different warp and weft densities, weaving patterns, and production speeds. Following identical black dyeing and finishing treatments, the range of the average quantity of MPFF released per fabric varies from 221 mg/kg to 753 mg/kg with an overall mean value of 451 mg/kg across all trials. Among the investigated parameters, warp yarn density and weaving pattern emerged as the most influential factors, accounting for the largest variations in MPFF release. Increasing warp density from 40 to 60 yarns/cm resulted in a substantial increase in MPFF emission, while the 3/1 sateen weave exhibited significantly lower MPFF release compared to plain and ottoman weaves. In contrast, weft density and weft insertion speed showed limited influence relative to experimental variability. No clear correlation was observed between the number of filaments in the weft yarn and MPFF release. These results show that the higher the surface mass, the cover factor, and the drape coefficient, the higher the release of MPFFs. This study shows that it is possible to limit the amount of microfibers generated by textiles by controlling the design and production of fabrics. The results support the integration of microplastic mitigation criteria into sustainable textile engineering and industrial eco-design frameworks. Nevertheless, the complexity of the release mechanisms and potential interactions between factors highlights the importance of conducting further research to determine the specific fabric characteristics that influence MPFF release. Full article

Conductive thread is an integral aspect of smart textiles in the domain of electronic textiles (e-textiles). This study unveils the development of twelve distinct variants of conductive threads using the twisting method: the fusion of copper filament with cotton and polyester threads. The threads are coated with a carbon paste solution enriched with dissolved sea salt. The carbon paste is obtained from non-functional dry cell batteries, conventionally categorized as hazardous electronic waste (e-waste), which underscores an economically viable and environmentally sustainable approach. Experiments proved that each variant demonstrates minimal electrical resistance. The lowest resistance, 0.0164 ± 0.0001 Ω/cm, was achieved by Carbon-Coated Cotton Twisted Copper Thread-II. Comparative evaluation with commercially available conductive threads, including Bekaert Bekinox^® VN type (12/1x275/100z), indicated comparable or moderately lower resistance values for the developed copper-based threads. Mechanical–electrical stability under bending, twisting, and wash–dry cycles confirmed consistent conductive performance with minimal resistance variation. Practical demonstrations further validated the integration of the threads into fabric-based flexible circuits and wearable electronic systems. These findings demonstrate that twisted copper-based conductive threads derived from sustainable coating materials provide a promising alternative for smart textile and wearable electronic applications. Future research should focus on scalable fabrication, enhanced coating fixation, and long-term durability assessment. Full article

This study presents the development of a three-dimensional (3D) filament assembly model for predicting the air permeability of woven fabrics composed of spun yarns. To address the limitations of conventional single-line yarn models, the proposed framework incorporates fiber-level geometric representations using non-uniform rational B-splines (NURBS) and simulates multiple weave patterns—including plain, basket, twill, and rib—under various set density configurations. Each yarn was modeled with accurate filament distribution and cross-sectional layering, enabling the construction of realistic unit-cell-based CAD geometries. Computational fluid dynamics (CFD) simulations were performed using the k-ε turbulence model in SolidWorks Flow Simulation and validated against experimental measurements conducted under ISO 9237:1995 conditions. The filament assembly model achieved high predictive accuracy, exhibiting a lower of percentage prediction errors than the single-line yarn path model, thereby more effectively capturing airflow behavior through inter-yarn and intra-yarn pores. These findings highlight the capability of integrated CAD/CFD methodologies for virtual prototyping of breathable textiles and provide a robust foundation for high-precision performance prediction in functional and technical fabric design. Full article

The purpose of this study is to combine 3D printing and hot-pressing to improve polyvinylidene fluoride (PVDF) by making its surface smoother, enhancing crystallinity and electrical and mechanical performance. Before printing, PVDF filament was analyzed using rheology, differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA), and extrusion tests. Based on these results for printing, 250 °C was fixed as the optimized printing temperature. PVDF samples were printed using an Ultimaker S5 dual-nozzle 3D printer, with a size of 30 × 30 × 0.2 mm³. After printing, samples were hot-pressed at five different temperatures, 100, 125, 150, 175, and 200 °C, for 10 min each. Then, the hot-pressed samples were tested using morphology, Fourier transform infrared (FTIR), X-ray diffraction (XRD), DSC, tensile, and electrical properties. From the morphology, the sample thickness decreased from 0.25 to 0.24 mm, making the surface smoother, removing pores after hot-pressing. From FTIR and XRD results, all samples showed similar patterns, but the hot-pressed sample showed slightly stronger β-phase diffraction and peaks near 20° and 840, 1066, and 1275 cm⁻¹, indicating better crystal ordering. The DSC results showed a small increase in melting temperature and stable thermal behavior after hot-pressing, confirming improved thermal stability. The tensile property results confirmed that the hot-pressed samples, around 150 and 175, showed higher strength and better flexibility. The electrical I-V test showed stable and uniform conductivity, and the hot-pressed samples performed more consistently. Overall, hot-pressing improved the surface quality, crystallinity, mechanical, and electrical properties of 3D-printed PVDF, making it more reliable for advanced applications. Full article

The Polyether ether ketone (PEEK) suffers from insufficient interlayer molecular chain diffusion and weak interfacial fusion during Fused Filament Fabrication (FFF) due to its high melt viscosity and rapid cooling characteristics, restricting the mechanical properties and engineering applications of printed parts. To improve the interlayer bonding quality of FFF-printed PEEK, an in situ preheating technology integrated into the print nozzle was proposed and implemented. Through a high-temperature controllable preheating system that moves synchronously with the nozzle, local precise heating is performed on the surface of the deposited layer to actively regulate the thermal history of the interlayer interface. Systematic studies on the effect of preheating temperature were conducted. The results show that the influence of preheating temperature on part performance follows a trend of first increasing and then decreasing. When the preheating temperature is 280 °C, the comprehensive performance of the specimens is optimal: the tensile strength reaches 69.47 MPa, which is 21.3% higher than that of the non-preheated reference group; the elongation at break is 71.07%; and the porosity decreases to 8.36%. Microstructural analysis reveals that moderate preheating facilitates molecular chain diffusion and interfacial fusion, whereas excessive heating induces thermal oxidative degradation of PEEK, resulting in deteriorated mechanical performance. These findings confirm that in situ preheating represents an effective approach for enhancing interlayer bonding, thereby offering a practical solution for the additive manufacturing of high-performance PEEK components. Full article

Heat creep is a critical failure mechanism in fused filament fabrication (FFF) extrusion systems, arising from insufficient thermal isolation between the hot end and cold end. It causes premature polymer softening, extrusion instability, and nozzle clogging, especially when active cooling is reduced or lost. This study experimentally evaluates passive cooling strategies for mitigating heat creep in consumer-class printers by exploiting ambient thermal stratification within the build volume. Vertical air-temperature gradients above heated build plates were measured for enclosed, semi-enclosed, and open-frame architectures, revealing pronounced stratification. Cold-end temperatures were then quantified for a stock extruder under forced and natural convection while printing polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). Finally, a modified cold-end using a heat pipe to relocate heat rejection to an elevated heat sink was tested under identical conditions, assuming fan failure. Elevated heat-rejection locations experienced lower ambient temperatures and improved natural-convection heat transfer. Relative to the stock configuration, the augmented design reduced cold-end temperatures and improved thermal stability during representative printing cycles without continuous active cooling—the improvement percent is ~8%. The results demonstrate that coupling heat-pipe conduction with environmental thermal gradients can mitigate heat creep and improve extruder reliability with lower energy demand. Full article

As additive manufacturing (AM) expands into high-end industries, ensuring both technical performance and dimensional accuracy remains a challenge. This paper addresses the challenge of integrating recycled materials into the field of plastic extrusion additive manufacturing technologies by conducting a study on the evaluation and optimization of thermoplastic extrusion parameters to improve the dimensional accuracy of additively manufactured parts from virgin and recycled polyethylene terephthalate glycol (PETG, rPETG) and acrylonitrile styrene acrylate (ASA), both in virgin and recycled form. To carry out the study, 180 three-point bending specimens were additively manufactured on the QIDI Q1 Pro 3D printer by thermoplastic extrusion of PETG, rPETG, ASA, rASA (45 specimens for each type of material), using the following variable parameters: layer height deposited in one pass L_h = (0.10–0.20) mm and filling percentage—I_d = (50–100)%. After manufacturing the specimens, the dimensional characteristics that will be determined by measurement were defined: L—length, WA—width A, HA—height A, WA’—width A’, and HA’—height A’. Dimensional accuracy was assessed through 900 measurements using a DeMeet 400 coordinate measuring machine and analyzing the arithmetic means, dispersions, and mean square deviations. The results of the study confirm the superior dimensional stability of virgin materials (18.77–20.04%) compared to recycled materials. The analysis demonstrates that by optimizing the process parameters, filaments from recycled materials (rPETG and rASA) can achieve acceptable precision, with average deviations of 0.25–0.78% from the nominal dimensions. The present study validates the use of rPETG and rASA as a viable alternative for applications that do not require critical tolerances. Full article

This study investigates the influence of layer height, infill density, and the number of perimeters on the FDM 3D printing performance of PLA, a biodegradable and renewable biopolymer. The primary objective is to identify parameter settings that simultaneously maximize impact strength and production efficiency, quantified through filament usage and printing time. In addition, 3D surface profilometry was employed as a non-destructive characterization method to evaluate surface roughness, assess its dependence on process parameters, and establish correlations with destructive impact strength testing. Experimental work was conducted using a Taguchi L9 orthogonal array, and regression-based mathematical models were developed to quantify the effects of individual parameters on the analysed responses. Finally, Grey Relational Analysis (GRA) was applied to perform multi-objective optimization and determine parameter combinations that jointly enhance mechanical durability, surface quality, and production efficiency. The results provide a clear set of manufacturing parameter settings that satisfy both destructive and non-destructive performance criteria while ensuring resource-efficient production. Full article

Aiming at the key problems of the material removal rate and surface integrity of existing tools in the lapping of sapphire hard and brittle crystals, an efficient lapping tool has been developed to explore a new process for HFVCD (hot filament chemical vapor deposition) diamond tools to efficiently lap sapphire wafers. With the premise of ensuring the surface roughness of the wafer is Ra ≤ 0.5 μm, the material removal rate is increased to more than 1 μm/h. To explore a high-efficiency lapping process for sapphire wafers using HFCVD diamond tools. The influence of key preparation parameters on the surface characteristics of CVD (chemical vapor deposition) diamond films was systematically investigated. Three types of CVD diamond coating tools with distinct surface morphologies were fabricated. These tools were subsequently employed to conduct lapping experiments on sapphire wafers in order to evaluate their processing performance. The experimental results demonstrate that the gas pressure, methane concentration, and substrate temperature collectively influenced the surface morphology of the diamond coatings. The fabricated coatings exhibited well-defined grain boundaries and displayed pyramidal, prismatic and spherical features, corresponding to high-quality microcrystalline and nanocrystalline diamond layers. In the lapping experiments, the prismatic CVD diamond coating tool exhibited the highest material removal rate, reaching approximately 1.7 μm/min once stabilized. The spherical diamond coating tool produced the lowest surface roughness on the lapped sapphire wafers, with a value of about 0.35 μm. Surface morphology-controllable diamond tools were used for the lapping processing of the sapphire wafers. This achieved a good surface quality and high removal rate and provided new ideas for the precision machining of brittle hard materials in the plane or even in the curved surface. Full article