Purinosomes spatially co-localize with mitochondrial transporters.

In this study, we advance our understanding of the spatial relationship between the purinosome, a liquid condensate consisting of six enzymes involved in de novo purine biosynthesis, and mitochondria. Previous research has shown that purinosomes move along tubulin toward mitochondria, suggesting a direct uptake of glycine from mitochondria. Here, we propose that the purinosome is located proximally to the mitochondrial transporters SLC25A13 and SLC25A38, facilitating the uptake of glycine, aspartate, and glutamate, essential factors for purine synthesis. We utilized the proximity ligation assay (PLA) and APEX proximity labeling to investigate the association between purinosome proteins and mitochondrial transporters. Our results indicate that purinosome assembly occurs close to the mitochondrial membrane under purine-deficient conditions, with the transporters migrating to be adjacent to the purinosome. Furthermore, both targeted and non-targeted analyses suggest that the SLC25A13-APEX2-V5 probe accurately reflects endogenous cellular status. These findings provide insights into the spatial organization of purine biosynthesis and lay the groundwork for further investigations into additional proteins involved in this pathway.

Biosynthesis of High Toughness Poly(3-Hydroxypropionate)-Based Block Copolymers With Poly(D-2-Hydroxybutyrate) and Poly(D-Lactate) Segments Using Evolved Monomer Sequence-Regulating Polyester Synthase.

This study synthesized poly(3-hydroxypropionate) [P(3HP)]-containing polyhydroxyalkanoate (PHA) block copolymers, P(3HP)-b-P[2-hydroxybutyrate (2HB)] and P(3HP)-b-P(D-lactate) (PDLA), using Escherichia coli. The cells expressing an evolved sequence-regulating PHA synthase, PhaCARNDFH, and propionyl-CoA transferase were cultured with the supplementation of the corresponding monomer precursors in the medium. The block structure of P(3HP)-b-PDLA was confirmed by proton nuclear magnetic resonance analysis and solvent fractionation. The molecular weights of the polymers were in the range of 0.8-2.8 × 105. The solvent-cast polymer films were subjected to isothermal treatment to promote phase separation and crystallization and were subsequently melt-quenched to produce an amorphous phase. The melt-quenched P(3HP)-b-P(2HB) film exhibited a high elongation at break (1153%), resulting in a toughness of 181 MJ/m3. The solvent-cast film of P(3HP)-b-65 mol% PDLA exhibited partial elastic deformation, in which the P(3HP) phase functioned as a soft segment. The melt-quenching of the polymer resulted in embrittlement presumably due to the high lactate fraction. Overall, the P(3HP)-based block copolymers exhibited several mechanical properties depending on the higher-order structure of the polymer and the properties of the P(2-hydroxyalkanoate) segments. This study findings show that P(3HP)-b-P(2HB) and P(3HP)-b-PDLA can function excellently if their microstructures are properly controlled.

On the Development of Polylactic Acid/Polycaprolactone Blended Films with High Retention Capacity.

The retention capacity of polymers is related to the development of systems that combine high surface-to-volume ratio with good handling and specific functionality. Biodegradability and biocompatibility are also key features for extending the field of applications to areas such as biomedicine. With this in mind, the aim of this work is to develop biodegradable, biocompatible, and highly functionalized porous films, that ensure suitable handling and a good surface-to-volume ratio. Polylactic acid (PLA) is applied as a polymer matrix to which a polycaprolactone with a star-shaped architecture (PCL-COOH) to ensure a high concentration of carboxylic end functionalities is added. The porous films are prepared using the phase inversion technique, which, as shown by Scanning Electron Microscopy (SEM) analysis, promotes good dispersion of the PCL-COOH domains. Absorption and release measurements performed with a positively charged model molecule show that the retention capacity and release rate can be tuned by changing the PCL-COOH concentration in the systems. Moreover, the adsorption properties for the formulation with the highest PCL-COOH content are also demonstrated with a real and widely used drug, namely doxorubicin. Finally, the bio- and hemocompatibility of the films, which are enzymatically degradable, are evaluated by using human keratinocytes and red blood cells, respectively.

Evaluating Osteogenic Cell Differentiation Efficacy in the Presence of Polylactide Samples with Varied Compositions for Bone Grafting: In Vitro Study.

In oral implantology, surgeons often confront the need to improve alveolar bone quality and volume before implantation in patients with bone defects. While Guided Bone Regeneration (GBR) with titanium meshes is a clinical "gold standard" for bone augmentation, mesh removal pre-implantation presents a drawback. This study explores biodegradable scaffolds as an alternative. The research investigates the impact of various compositions of customized bone grafting scaffolds on proliferation and osteogenic differentiation processes in vitro. Plates (10 x 10 x 0.5 mm) were fabricated from polylactide (PLA), PLA with 15% hydroxyapatite nanoparticles (PLA/HA), and polylactide with glycolic acid copolymers (PLGA 60:40 and 85:15). Gingival fibroblasts assessed the influence of experimental samples on proliferation and osteogenic differentiation in a low-glucose medium. Osteogenic differentiation was induced, and alizarin red staining measured extracellular matrix calcification via spectrophotometry. Active proliferation of gingival fibroblasts occurred along scaffold edges during cultivation. Although cells proliferated with experimental samples, rates were lower than control cells. PLA/HA showed higher alizarin red staining intensity, indicating enhanced matrix calcification. Experimental samples (PLA, PLA/HA, PLGA 85:15, PLGA 60:40) supported cell proliferation at lower rates than control. PLA/HA demonstrated increased matrix calcification. Biodegradable membranes were non-toxic, suggesting potential for bone augmentation.

Beyond the Liver: A Unique Case of Pyogenic Liver Abscess Caused by Peptostreptococcus micros Penetrating the Chest Wall.

Liver abscesses are uncommon pyogenic infections with diverse microbiology, often involving enteric gram-negative bacilli such as Escherichia coli and Klebsiella pneumoniae. Standard management includes antibiotic therapy and abscess drainage. We present a case of a 37-year-old male with chronic right upper quadrant abdominal pain, who was found to have an enlarging liver mass infiltrating the chest wall and right-side chest ribs, ultimately diagnosed as a large pyogenic liver abscess (PLA) extending into the chest wall. Notably, the abscess was attributed to Peptostreptococcus micros, a rarely isolated pathogen in liver abscesses. Despite initial unsuccessful percutaneous drainage, surgical intervention proved necessary for definitive treatment. This case underscores the diagnostic challenge posed by uncommon pathogens in liver abscesses and emphasizes the effectiveness of surgical drainage in managing refractory cases.

Predictive value of initial Lp-PLA2, NT-proBNP, and peripheral blood-related ratios for heart failure after early onset infarction in patients with acute myocardial infarction.

OBJECTIVE: To analyze the predictive value of lipoprotein-associated phospholipase A2 (Lp-PLA2), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and peripheral blood-related ratios at the initial diagnosis for heart failure (HF) after early-onset infarction in patients with acute myocardial infarction (AMI). METHODS: This retrospective analysis included 151 patients first diagnosed with AMI at Xianyang Central Hospital from February 2020 to February 2023. Patients were classified into two groups: those who developed HF during hospitalization (HF group, n=45) and those who did not (non-HF group, NHF, n=106). Differences in Lp-PLA2, NT-proBNP, and peripheral blood ratios at initial diagnosis were compared between the groups. Binary logistic regression was used to identify independent risk factors for HF, and a nomogram model was developed based on these factors. RESULTS: HR (P=0.032), C-reactive protein (CRP) (P<0.001), alanine aminotransferase (ALT) (P=0.015), coronary artery lesion score (CALDS) (P<0.001), D-dimer (D-D) (P=0.021), neutrophil-to-lymphocyte ratio (NLR) (P<0.001), Lp-PLA2 (P<0.001), and NT-proBNP (P<0.001) were significantly higher in the HF group than in the NHF group. Left ventricular end-systolic diameter (LVESD) (P<0.001) and left ventricular end-diastolic diameter (LVEDD) (P<0.001) were significantly lower in the HF group. Multifactorial logistic regression identified HR (P=0.034), CRP (P=0.028), CALDS (P=0.007), NLR (P=0.001), Lp-PLA2 (P=0.001), and NT-proBNP (P=0.002) as independent predictors of HF. The AUCs for NLR, Lp-PLA2, and NT-proBNP were 0.806, 0.849, and 0.780, respectively. The nomogram model achieved an AUC of 0.964, significantly outperforming individual indicators per Delong's test, highlighting its superior predictive efficacy. CONCLUSION: HR, CRP, CALDS, NLR, Lp-PLA2, and NT-proBNP were identified as independent predictors of HR post-AMI myocardial infarction. The constructed nomogram model provides an effective tool for early clinical identification of high-risk patients, potentially improving prognosis and guiding therapeutic strategies.

Insights into the response mechanisms of Tetradesmus obliquus to aged polylactic acid and tetracycline exposure via transcriptome analysis and physiological evaluations.

Microplastics (MPs) and antibiotics, identified as emerging pollutants, are extensively prevalent in aquatic environments and display prolonged durability. Unlike conventional plastics, biodegradable plastics are more susceptible to decomposition in the environment, resulting in the generation of microplastics and posing potential risks to the aquatic ecosystems. In this study, we assessed growth inhibition, chlorophyll a content, malondialdehyde content (MDA), and antioxidant enzyme activities. These measurements were integrated with transcriptome analysis to explore the response mechanisms of virgin and aged polylactic acid (vPLA and aPLA) and tetracycline (TC) following 14-day exposure to Tetradesmus obliquus, either individually or in combination. The findings indicated that exposure to vPLA did not significantly impact the growth of T. obliquus. Conversely, aPLA demonstrated growth-promoting effects on T. obliquus, particularly in the latter incubation stages. Moreover, a 14-day exposure significantly increased the chlorophyll a content and the activities of superoxide dismutase (SOD), catalase glutathione (CAT) and glutathione S-transferase (GST) within the algal cells. Apart from 1 mg L-1, the TC concentrations of 2.5, 5.0, and 10 mg L-1 exhibited significant toxic effects on T. obliquus, including growth inhibition, decreased chlorophyll a content, elevated activities of SOD, CAT, and GST, and increased MDA levels. Exposure to a combination of 300 mg L-1 aPLA and 5.0 mg L-1 TC, compared to solely 5 mg L-1 TC, demonstrated a notable reduction in TC toxicity to T. obliquus in the presence of aPLA. This was indicated by elevated algal cell density and chlorophyll a content, as well as a decrease in MDA content. Transcriptome analysis indicated an enrichment of differentially expressed genes (DEGs) in pathways linked to porphyrin metabolism, photosynthesis, carbon fixation, and metabolism within the aPLA+TC combined exposure. The study aid in expanding our knowledge of the potential ecological risks posed by biodegradable plastics and accompanying pollutants in aquatic environments.

Confinement Effect in Multilayer Films Made from Semicrystalline and Bio-Based Polyamide and Polylactic Acid.

Bio-based multilayer films were prepared by using the innovative nanolayer coextrusion process to produce films with a number of alternating layers varying from 3 to 2049. For the first time, a semicrystalline polymer was confined by another semicrystalline polymer by nanolayering in order to develop high barrier polyamide (PA11)/polylactic acid (PLA) films without compromising thermal stability and mechanical behavior. This process allows the preparation of nanostratified films with thin layers (down to nanometric thicknesses) in which a confinement effect can be induced. The stratified structure has been investigated, and the layer thicknesses have been measured. Barrier properties were successfully correlated to the microstructure, as well as the thermal behavior, and mechanical properties. The layer continuity was fully achieved for most of the films, but some layer breakups have been observed on the film with the thinnest PLA layer (2049-layers film). Coextruding PLA with PA11 has induced an increase in PLA crystallinity (from 4 to 16%) along with an increase in thermal stability of the multilayer films without impacting PA11 properties. Gas barrier properties were driven by the PLA confined layers due to the microstructural rearrangement by increasing crystallinity, whereas water barrier properties were governed by the PA11 confining layers due to its lower water affinity. As a consequence, a decrease of water permeability (up to 11 times less permeable for the 6M film) but an increase of gas barrier properties (barrier improvement factor (BIF) of 66% for the 0M film for N2 and BIF of 36% for the 6M film for CO2 for instance) were evidenced as the layer number was increased. This study paves the way for the development of ecofriendly materials with outstanding barrier performances and highlights the importance of nonmiscible polymers adhesion at melt state and additives presence.

Advanced biopolymeric materials and nanosystems for RNA/DNA vaccines: a review.

The post COVID-19 pandemic era has emerged with more efficient vaccines, all based on genetic materials. However, to expand the use of nucleic components as vaccines, a new generation of nanosystems particularly constructed to increase RNA/DNA stability, half-life and facilitate administration are still required. This review highlights novel developments in mRNA and pDNA vaccines formulated into nanostructures exclusively composed by biopolymeric materials. Recent advances suggest that a new generation of vaccines may arise by adapting the structural features of biopolymers with the effectiveness of nucleic acids. The advantages offered by biopolymers, such as increased stability and targeting ability may cause a revolution in the immunization field for offering promptly adaptable and effective formulations for worldwide distribution.

[Box: see text].

Size-dependent effect on controllable release and field insecticidal efficacy of diamide insecticide polylactic acid microspheres delivery systems against Ostrinia nubilalis.

New nano/microcarriers of pesticides represent a highly promising novel field for sustainable pest management. However, despite extensive laboratory research, few studies on the design and evaluation of nanopesticides for field applications exist. In this study, we present a straightforward and green synthetic method of ultrasonic-assisted and hydrogen-bonded self-assembly at the oil-water interface for the synthesis of polylactic acid (PLA) microspheres encapsulating chlorantraniliprole (CAP), with precise control over the size of the microspheres. The resulting CAP-loaded PLA microspheres (CAP-PLA MS) exhibit both high pesticide encapsulation efficiency and stability in natural environments. It has been determined that non-Fickian diffusion mainly controls pesticide release, thus enabling dynamic control over molecular transport speeds. Importantly, our functional CAP-PLA MS demonstrates superior sustained pesticide release performance under both laboratory and field conditions while maintaining better exceptional insecticidal efficacy than normal CAP in controlling O. nubilalis at a concentration of 30 or 45 g/ha. Consequently, we propose that our functional PLA microspheres could serve as ideal pesticide carriers in the sustained treatment of O. nubilalis.

Accelerated aging behavior of degradable and non-degradable microplastics via advanced oxidation and their adsorption characteristics towards tetracycline.

The increasing global utilization of biodegradable plastics due to stringent regulations on traditional plastics has caused a significant rise in microplastic (MPs) pollution in aquatic ecosystems from biodegradable products. However, the environmental behavior of biodegradable MPs remains inadequately elucidated. This study explored the aging processes of polylactic acid (PLA) and polystyrene (PS) under a heat-activated potassium persulfate (K2S2O8) system, as well as their adsorption characteristics towards tetracycline (TCs). In comparison to PS, the surface structure of PLA experienced more pronounced changes over aging, exhibiting evident pits, cracks, and fragmentation. The carbonyl index (CI) and oxygen/carbon ratio (O/C) of PS displayed exponential growth over time, whereas the values for PLA showed linear and exponential increases, respectively. The adsorption capacity of TCs by PS and PLA aged for 6 days increased from 0.312 mg‧g-1 and 0.457 mg‧g-1for original PS and PLA, respectively, to 0.372 mg‧g-1 and 0.649 mg‧g-1. Meanwhile, the adsorption rate (k2 values) for TCs decreased by 42.03 % for PS and 79.64 % for PLA compared to their initial values. The findings indicated that biodegradable PLA-MPs may exhibit higher tetracycline carrying capacities than PS, potentially increasing environmental and organismal risks, particularly in view of aging effects.

Poly (lactic acid)/ amine grafted mesoporous silica-based composite for food packaging application.

The present study focuses on the development of environmentally friendly bio-composite films using poly(lactic acid) (PLA) as a biopolymer matrix. This is achieved by incorporating amine functionalized green mesoporous silica (GMS) and employing a solution casting method for film fabrication. The motivation behind the work is to improve the compatibility between PLA and green mesoporous silica sourced from rice husk by functionalizing GMS with APTES (3-Aminopropyltriethoxy silane). The primary objective is to explore how the inclusion of GMS influences both the physicochemical attributes and the efficacy of active food packaging in PLA. The introduction of GMS to the PLA matrix not only improves the flexibility of PLA/GMS composite films but also enhances their overall performance. The reinforcement of GMS in the PLA matrix has also significantly contributed towards the reduction in oxygen transmittance rate and provided an anti-bacterial effect towards pathogen i.e. S. aureus and E. coli. The PLA/GMS composite films exhibit antioxidant activity acting as potential scavengers with around 78 % efficacy against DPPH (2,2-diphenyl-1-picrylhydrazyl). Consequently, the PLA/GMS composite formulation proposed in this study shows promising outcomes in terms of strength, flexibility, antioxidant properties, and antibacterial characteristics. Also, the PLA/GMS films extended the shelf life of cut apple samples for seven days.

Effect of Degradation of Polylactic Acid (PLA) on Dynamic Mechanical Response of 3D Printed Lattice Structures.

Material-extrusion-based 3D printing with polylactic acid (PLA) has transformed the production of lightweight lattice structures with a high strength-to-weight ratio for various industries. While PLA offers advantages such as eco-friendliness, affordability, and printability, its mechanical properties degrade due to environmental factors. This study investigated the impact resistance of PLA lattice structures subjected to material degradation under room temperature, humidity, and natural light exposure. Four lattice core types (auxetic, negative-to-positive (NTP) gradient in terms of Poisson's ratio, positive-to-negative (PTN) gradient in terms of Poisson's ratio, and honeycomb) were analyzed for variations in mechanical properties due to declines in yield stress and failure strain. Mechanical testing and numerical simulations at various yield stress and failure strain levels evaluated the degradation effect, using undegraded material as a reference. The results showed that structures with a negative Poisson's ratio exhibited superior resistance to local crushing despite material weakening. Reducing the material's brittleness (failure strain) had a greater impact on impact response compared to reducing its yield stress. This study also revealed the potential of gradient cores, which exhibited a balance between strength (maintaining similar peak force to auxetic cores around 800 N) and energy absorption (up to 40% higher than auxetic cores) under moderate degradation (yield strength and failure strain at 60% and 80% of reference values). These findings suggest that gradient structures with varying Poisson's ratios employing auxetic designs are valuable choices for AM parts requiring both strength and resilience in variable environmental conditions.

Differentiation between Hydrolytic and Thermo-Oxidative Degradation of Poly(lactic acid) and Poly(lactic acid)/Starch Composites in Warm and Humid Environments.

For the application of poly(lactic acid) (PLA) and PLA/starch composites in technical components such as toys, it is essential to know their degradation behavior under relevant application conditions in a hydrothermal environment. For this purpose, composites made from PLA and native potato starch were produced using twin-screw extruders and then processed into test specimens, which were then subjected to various one-week ageing processes with varying temperatures (23, 50, 70, 90 °C) and humidity levels (10, 50, 75, 90%). This was followed by mechanical characterization (tensile test) and identification of degradation using Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance spectroscopy (NMR). With increasing temperature and humidity, there was a clear degradation of the PLA, which could be reduced or slowed down by adding 50 wt.% starch, due to increased crystallinity. Hydrolysis was identified as the main degradation mechanism for PLA and PLA/starch composites, especially above the glass transition temperature, with thermo-oxidative degradation also playing a subordinate role. Both hydrolytic degradation and thermo-oxidative degradation led to a reduction in mechanical properties such as tensile strength.

Evaluation of the Effect of Mineral Oil Exposure on Changes in the Structure and Mechanical Properties of Polymer Parts Produced by Additive Manufacturing Techniques.

The paper describes the type of changes in the structure and mechanical properties of 3D printed shapes under the influence of mineral oil. The effects of a room (23 °C) and elevated temperature (70 °C) on 3D prints manufactured by the FDM method and stored in oil for 15, 30, and 60 days on the change of properties and structure were investigated. The samples were produced from ABS (poly(acrylonitrile-co-butadiene-co-styrene)), ASA (poly(acrylonitrile-co-styrene-co-acrylate), PLA (poly(lactic acid)), and HIPS (high-impact polystyrene). Tests related to the strength of the materials, such as the static tensile test and Charpy impact test, were carried out. The structure was evaluated using a scanning electron microscope, and changes in chemical structure were determined by conducting FTIR (Fourier transform infrared spectroscopy) and TGA (thermogravimetric analysis) tests. The analysis of the results provided important information about the impact of mineral oil on specific materials. This is critical for designing and manufacturing components that can withstand mineral oil exposure in real-world environments. The materials underwent varying changes. Strength increased for PLA by about 28%, remained unchanged for ABS and HIPS during exposure for 30 days, and decreased for ASA with extended exposure up to 14%.

Rheological Changes in Bio-Based Filaments Induced by Extrusion-Based 3D Printing Process.

In this work, the authors investigated the impact of extrusion-based printing process on the structural characteristics of bio-based resins through rheological measurements. Two commercially available filaments made from unfilled and wood-filled polylactide (PLA) polymers were considered. Three-dimensional specimens were prepared by printing these filaments under various operating conditions, i.e., changing the extruder temperature and printing rate, and examined using time sweep tests. Specific cycle rheological testing was conducted on pelletized filaments to simulate temperature changes in the printing process. The rheological characteristics of unprocessed materials, in terms of storage (G') and loss (G″) moduli, were found to be slightly affected by temperature changes. For a pure polymer, the G' slope at a low frequency decreased over time, showing that the polymer chains evolved from a higher to a lower molecular weight. For wood-filled materials, the G' slope rose over the testing time, emphasizing the formation of a percolated network of structured filler within the matrix. On the other side, the rheological parameters of both materials were strongly impacted by the printing extrusion and the related conditions. At lower nozzle temperatures (200 °C), by decreasing the printing speed, the G' and G″ curves became increasingly different with respect to unprocessed resin; whereas at higher nozzle temperatures (220 °C), the influence of the printing speed was insignificant, and all curves (albeit distant from those of unprocessed matrix) mainly overlapped. Considerations on degradation kinetics of both materials during the printing process were also provided by fitting experimental data of complex viscosity with linear correlation over time.

An Analysis of the Displacements in 3D-Printed PLA Acoustic Guitars.

This study focuses on the analysis of the displacements generated in 3D-printed acoustic guitar tops. Specifically, the influence of 3D printing direction parameters on the vibrational behavior of a guitar top designed for polylactic acid (PLA) by analyzing five points of the top surface at a reduced scale. For this purpose, finite element tests and laboratory experiments have been carried out to support the study. After analyzing the results, it can be affirmed that the vibrational response in reduced-scale top plates can be modified and controlled by varying the printing direction angle in additive manufacturing, providing relevant information about the displacement in the vibrational response of PLA acoustic guitars. Furthermore, this work shows that the behavior of a specific acoustic guitar design can be characterized according to a specific need.

Fatigue Performance of 3D-Printed Poly-Lactic-Acid Bone Scaffolds with Triply Periodic Minimal Surface and Voronoi Pore Structures.

Bone scaffolds serve a crucial role in tissue engineering, particularly in facilitating bone regeneration where natural repair is insufficient. Despite advancements in the fabrication of polymeric bone scaffolds, the challenge remains to optimize their mechanical resilience. Specifically, research on the fatigue behaviour of polymeric bone scaffolds is scarce. This study investigates the influence of pore architecture on the mechanical performance of poly-lactic-acid (PLA) scaffolds under quasi-static and cyclic compression. PLA scaffolds with a 60% porosity were fabricated using extrusion-based 3D printing in various designs: Gyroid, Lidinoid, Fischer-Koch, IWP, and Voronoi. Results demonstrated that Gyroid scaffolds had the highest compressive strength (6.6 MPa), followed by Lidinoid, Fischer-Koch, IWP, and Voronoi designs. Increased strut thickness was linked to higher compressive strength. However, normalized fatigue resistance showed a different pattern. While scaffolds resisted fatigue cycles at low strain amplitudes, fatigue damage was observed at higher strains. Voronoi structures exhibited the highest normalized fatigue performance, enduring around 58,000 cycles at 85% strain amplitude, followed by Gyroid, Fischer-Koch, Lidinoid, and IWP structures. Enhanced fatigue performance in different topologies correlated with the minimum cross-sectional area of scaffolds. Given the importance of both static and fatigue strength, the Gyroid topology emerges as the superior choice overall.

Analysis of the Impact of Cooling Lubricants on the Tensile Properties of FDM 3D Printed PLA and PLA+CF Materials.

This study investigates the impact of infill density on the mechanical properties of fused deposition modeling (FDM) 3D-printed polylactic acid (PLA) and PLA reinforced with carbon fiber (PLA+CF) specimens, which hold industrial significance due to their applications in industries where mechanical robustness and durability are critical. Exposure to cooling lubricants is particularly relevant for environments where these materials are frequently subjected to cooling fluids, such as manufacturing plants and machine shops. This research aims to explore insights into the mechanical robustness and durability of these materials under realistic operating conditions, including prolonged exposure to cooling lubricants. Tensile tests were performed on PLA and PLA+CF specimens printed with varying infill densities (40%, 60%, 80%, and 100%). The specimens underwent tensile testing before and after exposure to cooling lubricants for 7 and 30 days, respectively. Mechanical properties such as tensile strength, maximum force, strain, and Young's modulus were measured to evaluate the effects of infill density and lubricant exposure. Higher infill densities significantly increased tensile strength and maximum force for both PLA and PLA+CF specimens. PLA specimens showed an increase in tensile strength from 22.49 MPa at 40% infill density to 45.00 MPa at 100% infill density, representing a 100.09% enhancement. PLA+CF specimens exhibited an increase from 23.09 MPa to 42.54 MPa, marking an 84.27% improvement. After 30 days of lubricant exposure, the tensile strength of PLA specimens decreased by 15.56%, while PLA+CF specimens experienced an 18.60% reduction. Strain values exhibited minor fluctuations, indicating stable elasticity, and Young's modulus improved significantly with higher infill densities, suggesting enhanced material stiffness. Increasing the infill density of FDM 3D-printed PLA and PLA+CF specimens significantly enhance their mechanical properties, even under prolonged exposure to cooling lubricants. These findings have significant implications for industrial applications, indicating that optimizing infill density can enhance the durability and performance of 3D-printed components. This study offers a robust foundation for further research and practical applications, highlighting the critical role of infill density in enhancing structural integrity and load-bearing capacity.

Synergistic effect of TiO2 nanoparticles and poly (ethylene-co-vinyl acetate) on the morphology and crystallization behavior of polylactic acid.

The impact of adding ethylene vinyl acetate copolymer (EVA 80) and 1 wt% TiO2 nanoparticles on the morphology and crystallization behavior of poly(lactic acid) blends was investigated using DSC, SEM, and POM. Thermal analysis revealed the enhancement of crystallinity of PLA in the presence of TiO2 and higher EVA 80 content in the blend. The PLA and EVA 80 components showed compatibility, as evidenced by the shift of the glass transition temperatures of the PLA phase in the blend to lower values compared to neat PLA. The lower temperature shift of the cold crystallization of the PLA and the formation of the small spherulites of the PLA in the blends indicated that the EVA 80 and TiO2 act as a nucleating agent for crystallization. The non-isothermal crystallization parameters of the composites were evaluated using Avrami's modified model, the MO approach, and Friedman's isoconversional method. The Avrami's modified rate constant (K) and the effective activation energy values significantly increased with the incorporation of EVA 80 and TiO2 nanoparticles. Furthermore, the thermogravimetric analysis (TGA) showed improved thermal stability of PLA by adding EVA 80 and TiO2.