Search Results (441)

Micro-structured SAE H13 tool steel inserts for polymer injection molding require accurate replication of sub-millimeter features while retaining adequate densification and heat-treatment response. This study compared two powder-based routes on the same hemispherical insert containing pyramidal features of approximately 0.145 mm base width: hot embossing (HE) of water-atomized SAE H13 powder (supplier d50 = 5.7 µm, irregular morphology) compounded with a commercial M1 binder, and material extrusion (MEX) of a commercial gas-atomized SAE H13 filament processed on a Markforged Metal X. Rheological screening selected a 57:43 vol% powder-to-binder ratio for the in-house HE feedstock, and DSC/TGA measurements defined two-step debinding windows. The best HE conditions were 220 °C, 8 MPa, and 45 min for the in-house mixture, and 210 °C, 8 MPa, and 30 min for the granulated commercial filament; the latter showed a 0.15% linear deviation from the silicone replica diameter among the best-rated samples. Under the tested commercial MEX configuration, the pyramidal features were not resolved because the 0.40 mm deposition line width exceeded the target feature base width, causing the slicer to omit the sub-line-width geometry. The defect populations differed qualitatively: HE specimens showed porosity and local cracking associated with powder morphology and pressureless sintering, whereas MEX specimens showed build-direction-aligned inter-raster voids associated with the toolpath. Microhardness and tensile data are therefore interpreted as process-history-specific results rather than as a direct route ranking, because sintering conditions were not uniform across all specimens. The study defines an experimentally bound process-selection limit for SAE H13 micro-tooling: HE remains preferable for sub-nozzle surface features, whereas MEX remains attractive for macro-scale geometric freedom, if resolution, densification, and post-sintering consolidation are addressed. Full article

Syzygium polyanthum (Wight) Walp., commonly known as Indonesian bay leaf or Daun salam, is widely used as a culinary and traditional botanical resource. However, region-specific information on its lipophilic constituents remains limited, and the sustainability implications of solvent-dependent phytochemical profiling are rarely addressed. This study characterized the GC–MS-detectable volatile lipophilic constituents of a selected nonpolar fraction of S. polyanthum leaves collected from Paniki Bawah, Mapanget District, Manado, Indonesia, using GC–MS, while evaluating solvent-related limitations for future greener extraction strategies. Dried leaf powder was macerated with 96% ethanol, followed by liquid–liquid partitioning with n-hexane and ethyl acetate. The n-hexane fraction was separated by silica gel column chromatography, and a TLC-selected fraction was analyzed by GC–MS. Compound annotation was supported by NIST 17 library matching, retention-index comparison using a C8–C40 n-alkane series, diagnostic ion evaluation, solvent blank analysis, and triplicate injections. Ethanolic extraction of 900 g dried powder yielded 87.0 g crude extract (9.67%). The n-hexane, ethyl acetate, and aqueous fractions yielded 5.98%, 21.15%, and 72.87%, respectively. GC–MS analysis tentatively annotated 11 compounds representing 94.44% of the total normalized peak area. The major constituents were palmitic acid, phytol, squalene, and neophytadiene. All annotations showed match scores of 90–98%, ΔRI values of 4–8 units, and RSD values of 1.86–3.27%. Although ethanol use, sunlight drying, solvent recovery, and recirculating chiller-assisted evaporation partially aligned with green chemistry principles, the use of n-hexane and chloroform means that the workflow should not be described as fully green. This study provides a baseline GC–MS fingerprint to support future greener extraction optimization. Full article

The increasing demand for porous stainless-steel materials produced by selective laser melting (L-PBF) for biomedical implants, filtration systems, heat exchangers, and energy devices has created an urgent need to improve their mechanical performance. Optimizing process parameters and microstructural properties is therefore critical for enhancing the overall functionality and reliability of L-PBF porous stainless-steel structures. This paper studies the effect of an aging heat treatment on the mechanical properties of L-PBF specimens, manufactured with stainless steel Uddeholm Corrax powders. The porosity was selected to be about 3%, based on manufacturer’s experience on the production injection mold inserts, with the ability to drain air. To reach this porosity, a set of manufacturing variables were selected, quantified in terms of VED (Volumetric Energy Density) of 59.01 J/mm³. The analysis of the mechanical behavior was focused on the compressive and flexural strength, dynamic Young’s modulus and the energy dissipation during earlier fatigue loading cycles. This study concluded that the heat treatment produces a negligible effect on dynamic Young’s modulus and increases the bending strength by about 25% and the compressive plateau strength by about 17%. Both specimens’ batches exhibit similar fatigue strain accumulation for cyclic compressive tests. Full article

S136 mold steel is widely used in the injection molding industry due to its excellent properties. However, during actual production, the mold is inevitably exposed to harsh service conditions involving high temperature, high pressure, chemical corrosion, and mechanical wear, leading to risks of failure caused by pitting corrosion, intergranular corrosion, electrochemical corrosion, selective dissolution, and surface fatigue wear. To enhance the surface protection performance of the mold, a TiC-reinforced 440C stainless steel composite coating was fabricated on the S136 substrate using plasma spray welding technology. Composite powders with different TiC contents (wt.%) were prepared via mechanical mixing. The phase composition, microstructure, microhardness, corrosion resistance, and wear resistance of the coatings were characterized by XRD, SEM, Vickers microhardness tester, electrochemical workstation, and vertical universal friction and wear tester. Furthermore, the corresponding strengthening mechanisms were elucidated. The results show that the incorporation of TiC refines the microstructure and synergistically enhances both corrosion and wear resistance. Among the tested coatings, the one with 1.0 wt.% TiC exhibits the best overall performance, with a significantly increased microhardness of 858.85 HV (approximately 1.5 times that of the substrate), an Ecorr of –0.286 ± 0.002 V, an Icorr of 4.51 × 10⁻⁷ A·cm⁻², and a friction coefficient of 0.591. This study provides important theoretical and technological insights for the surface strengthening of S136 mold steel using plasma spray welding of TiC/440C composite coatings to improve corrosion and wear resistance and extend service life. Full article

The widespread adoption of additive manufacturing, particularly selective laser sintering (SLS), has raised concerns about the disposal of unused thermoplastic powder residues, such as polyamide 12 (PA12). The high cost of PA12 and its degradation during the SLS process highlight the need for sustainable reuse strategies. This study evaluates the feasibility of reprocessing non-sintered PA12 powder without the addition of virgin material through fused deposition modeling (FDM) and injection molding (IM). Thermal analysis showed that the material retains processing temperatures comparable to virgin PA12. However, a significant reduction in melt flow index (≈61%) was observed, reflecting reduced processability and suggesting molecular-level changes affecting chain mobility. Injection molding demonstrated consistent mechanical behavior and good ductility, confirming its suitability for processing recycled PA12. In contrast, FDM processing resulted in higher variability and reduced ductility, mainly due to limitations in interlayer bonding associated with the increased viscosity of the material. Overall, the results highlight injection molding as a robust route for the valorization of non-sintered PA12, while FDM remains a feasible but less reliable alternative requiring further optimization. Full article

The corrosion behaviour and environmental durability of injection- and compression-moulded Nd–Fe–B and Sm–Fe–N magnets were investigated. For injection-moulded magnets, the effects of magnetic powder type (Nd–Fe–B and Sm–Fe–N), magnetic powder particle size (100 µm and 400 µm), and polymer binder (PPS and PA12) on corrosion resistance were studied. For compression-moulded magnets with an epoxy binder, the effects of powder type and size were examined. Corrosion resistance was investigated using potentiodynamic polarisation in electrolytes of varying pH (1.8–12.8). The Sm–Fe–N magnets exhibited slightly better corrosion resistance than the Nd–Fe–B magnets, irrespective of the polymer binder. The finer magnetic powders (100 µm) showed lower corrosion resistance due to their larger specific surface area, with a more pronounced effect in the compression-moulded magnets. The type of polymer binder had only a minor effect. The hygrothermal corrosion resistance and thermal stability were evaluated using bulk corrosion (BCT) and thermal shock tests, respectively. Surface corrosion was observed in all magnets after the BCT, with the compression-moulded magnets exhibiting a greater irreversible loss of magnetic properties. The thermal shock test caused a temporary reduction in magnetic properties, with recovery after remagnetisation, demonstrating the good thermal stability of both magnet types. Full article

Background/Objectives: This investigation aims to assess the potential for repurposing nitazoxanide (NIT) as a treatment for COVID-19. NIT was loaded into terpene-enriched chondrosomes (TECs) to assess its anti-hCoV-19 activity through pulmonary delivery. Methods: NIT-TECs were then fabricated utilizing the ethanol injection method. Using a D-optimal design, the effects of factors on entrapment efficiency (EE%), particle size (PS), and zeta potential (ZP) were determined, and the optimal formulation was selected. Results: The optimum TEC exhibited an EE% of 98.87 ± 0.69, a PS of 129.43 ± 5.43 nm, a polydispersity index (PDI) of 0.433 ± 0.022, and a ZP of −25.99 ± 0.99 mV. The optimum TEC was lyophilized to attain a dry powder. Further, the differential scanning calorimetry test confirmed that NIT was transformed from crystalline to amorphous form inside the optimum TEC. In addition, the mucoadhesion test confirmed the ability of the optimum TECs to adhere to pulmonary tissues. Additionally, NIT binding to the active site of SARS-CoV-2 enzymes was investigated using in silico analysis. When compared to NIT, the aerodynamic characteristics of the lyophilized optimum TECs employing the cascade impactor showed superior residence in the lungs. Conclusions: These findings suggest that loading NIT into TECs enhanced its antiviral activity, as indicated by the in vitro cytotoxicity study. Overall, the results point to NIT-loaded TECs as a potentially effective pulmonary delivery system for COVID-19 treatment. Full article

Background: With the increasing demand for non-surgical facial rejuvenation, injectable collagen biostimulators such as poly-L-lactic acid (PLLA), calcium hydroxyapatite (CaHA), polycaprolactone (PCL), poly-D,L-lactic acid (PDLLA) and powdered polydioxanone (PPDO) have become widely used by facial aesthetic practitioners. These agents stimulate neocollagenesis, providing gradual improvement in skin firmness, elasticity and facial contour with long-lasting results. While manufacturers emphasize the efficacy and favorable safety profile of these products, adverse events such as nodules, edema, inflammatory reactions and, in rare cases, granulomas have been reported. To date, no comprehensive systematic review has evaluated the proportion and nature of adverse effects associated with all major collagen biostimulators in facial aesthetic procedures. This study aims to synthesize current evidence on the proportion of adverse events linked to injectable collagen biostimulators. Methods: The systematic review will include clinical studies involving adults undergoing facial aesthetic procedures with PLLA, PDLLA, CaHA, PCL and PPDO that report adverse events during or after treatment. The search will be conducted in six main databases: CENTRAL, EMBASE, LILACS, PubMed, SCOPUS and Web of Science. No restrictions will be applied regarding language or publication date. The screening process will occur in two phases: first, two independent reviewers will assess titles and abstracts against the eligibility criteria; second, the same reviewers will conduct full-text evaluations. Data will be synthesized narratively, with a meta-analysis of proportions performed if appropriate. Additionally, sample characteristics, treatment protocols, study design and main findings will be reported. The risk of bias will be assessed independently by two reviewers using appropriate tools, based on the study design, with the support of artificial intelligence. PROSPERO registration number: CRD420251062785. Full article

Traditional enzyme-induced carbonate precipitation (EICP) technology for brick crack rehabilitation is commonly plagued by solution clogging and low repair efficiency. To overcome these technical limitations, a novel centrifugal cementation method was proposed in this study, with its core innovation lying in decoupling the EICP reaction from the masonry reinforcement process. After the complete reaction of urease with the cementation solution, a high-concentration calcium carbonate colloid was extracted via centrifugation, which was then mixed with fine sand to prepare a repair mortar for direct injection into brick cracks. The experimental results, based on a single-factor design with a fixed soybean powder concentration (180 g/L, peak urease activity), showed that the maximum flexural strength of the repaired bricks reached 2.31 MPa, recovering as much as 122.9% of that of the cracked unrepaired bricks. Furthermore, the flexural strength of the repaired bricks exhibited a significant positive correlation with the calcium carbonate content (20–100%) and curing time (3–28 days). Phase analysis indicated that the repair mortar was primarily composed of calcite and quartz. The high shear force generated by centrifugation triggered explosive nucleation of calcium carbonate, and spherical calcite particles were formed through Ostwald ripening, exhibiting a distinct characteristic of decoupling between the spherical morphology and calcite crystal phase. The centrifugal cementation method proposed in this study achieves excellent short-term repair effects for masonry structures under laboratory conditions, thus providing a novel technical approach for the crack rehabilitation of masonry structures. Full article

Background: Maintaining therapeutic meropenem plasma concentrations requires prolonged infusion, but stability concerns exist between preparation and administration. This study compared the stability and operability of ready-to-use powder–liquid double-chamber bag (DCB) infusions versus traditional powder-for-injection (PFI) meropenem under clinical conditions. Methods: Infusions at clinically relevant concentrations were stored at 2–8 °C, 25 ± 5 °C, and 40 ± 2 °C for 12 h. Stability assessments included appearance, pH, osmolality, insoluble particle count, meropenem content (HPLC), and impurity A level. Results: DCBs demonstrated superior content uniformity, significantly fewer insoluble particles (p < 0.05), and greater operational simplicity compared to PFI. Refrigeration maintained meropenem content > 95% and effectively suppressed impurity formation for up to 12 h. However, at both room temperature and elevated temperature, impurity A exceeded pharmacopoeial limits within 2 h, particularly at higher concentrations. An innovative bedside solvent volume adjustment method enabled DCBs to deliver high-concentration infusions, facilitating individualized critical care dosing. Conclusions: Compared with traditional powder injection formulations, the Meropenem powder–liquid dual-chamber bag offers more convenient operation under routine preparation conditions and poses a lower risk of contamination during the preparation process. Its stability is more sensitive to storage temperature, requiring strict adherence to refrigeration conditions. When stored under standardized conditions, the dual-chamber bag can better ensure drug efficacy stability and medication safety, making it particularly suitable for clinical emergency use and standardized workflow management. Full article

The transition to a circular economy requires assessment tools that capture not only the environmental and economic performance of products but also their circular design, functionality, and durability. While Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) are widely used, they alone do not capture modularity, reparability, reuse potential, or product lifespan. This study introduces a novel, integrated framework combining LCA, LCC, and product-level circularity indicators to provide a holistic evaluation of sustainability and circularity. In this study, two types of injection molds for plastic part production are compared: a conventionally manufactured mold and an additively manufactured metal mold produced by Laser Powder Bed Fusion (L-PBF) technology. The comparison integrates Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and a set of micro-circularity indicators, including the Material Circularity Indicator (MCI), Recycling Desirability Index (RDI), circular design guidelines (CDG), Disassembly Effort Index (DEI), longevity indicator (LI), and Circular Economy Indicator Prototype (CEIP). Results show that the AM mold exhibits lower environmental impacts across almost all categories, while its slightly higher initial cost is largely offset by reduced indirect costs over the product lifecycle. Micro-circularity indicators reveal that the AM mold achieves higher material circularity and better circular design performance (MCI, CDG, CEIP) but shows only minor improvements in disassembly and recyclability (DEI, RDI) and lower longevity (LI) compared to the conventional mold, highlighting potential limitations for remanufacturing and end-of-life recovery. The novelty of this study lies in the integrated application of LCA, LCC, and multiple micro-circularity indicators, providing an operational framework for evaluating circular design, reparability, and durability in additive manufacturing and enabling informed, holistic decision-making for truly circular products. Full article

Metal–polymer hybrid joints are gaining importance as they combine high structural rigidity with a low weight. Additive manufacturing processes such as the laser powder bed fusion process (L-PBF) enable the production of complex metallic lattice structures that allow for form-fitting force transmission between the metal and polymer as mechanical interlock elements. In this work, metal–polymer hybrid compounds with additively manufactured transition zones are systematically investigated and mechanically evaluated. Three different lattice geometries (z4A, z8A, z8V) were fabricated from maraging steel (1.2709) using L-PBF and then hybridised with injection moulding using polypropylene (PP C7069-100NA). Mechanical characterisation was performed by tensile tests according to DIN EN ISO 527, in combination with statistical analyses and an analytical serial three-spring model to determine the homogenised elasticity modulus of the transition zone. The results show significant geometry-related differences in tensile strength, maximum force, and effective stiffness. The A-shaped transition zone geometry (z4A) achieves the highest mechanical performance and up to 82% of the tensile strength of the pure polymer, while the V-shaped transition zone geometry (z8V) has significantly lower load-bearing capacities. Variance analysis shows a dominant geometric influence with effect strength of η² ≈ 0.99. The analytically predicted stiffness values match the experimental results within 5–10%. This work demonstrates a reproducible, simulation-sparse approach to the analysis and design of metal–polymer hybrid connections. Full article

Oak trees are widely distributed nationwide and account for approximately 24% of the total forest area in South Korea. However, these species are currently threatened by oak wilt disease caused by Dryadomyces quercus-mongolicae, leading to significant economic and ecological losses in the forestry industry. This study evaluated the effectiveness of culture suspension and lyophilized powder formulations of Streptomyces blastmyceticus in controlling oak wilt disease on Mongolian oak (Quercus mongolica). Field experiments were conducted using trunk and root injection methods in Q. mongolica plantations. The non-conductive area (NCA) of sapwood and colonization rate of the oak wilt fungus were analyzed and compared across treatments. In the Chuncheon experiment, Kangwon province, only the root injection of fungicide showed a significant difference compared to the culture suspension treatments. There were no significant differences between culture suspension and lyophilized powder treatments in Uiwang, Gyeonggi Province. Specifically, both preventive and curative treatments using culture suspension and lyophilized powder of S. blastmyceticus resulted in significantly different NCA values compared to the negative control (8.7%) and positive control (88.5%). The NCA for culture suspension ranged from 33.3% to 49.9%, and for lyophilized powder, from 37.3% to 43.9%. The colonization rate of the oak wilt fungus was lowest (9.72%) in the preventive treatment using lyophilized powder via trunk injection. For the culture suspension, the lowest colonization rate (20.83%) was observed in the curative treatment using trunk injection. These findings suggest that the lyophilized powder formulation of S. blastmyceticus efficiently suppresses the progression of oak wilt disease under field conditions. Full article

Background: Fixed-dose combination drugs (FDCs) are combinations of two or more active ingredients in a single dosage form. These formulations have proven effective in combating the development of resistance in diseases such as tuberculosis and malaria. Despite the benefits observed in the aforementioned cases, fixed-dose antibiotics combinations (FDACs) are increasingly raising questions about their rationality. This is the case for several FDACs listed in the AWaRe classification as not recommended, which unfortunately remain available on the pharmaceutical market, particularly in low- and middle-income countries like the Democratic Republic of Congo (DRC). Objectives: To identify the essential medicines available in pharmacies open to the public in the city of Kinshasa and to assess their inclusion in the DRC’s National List of Essential Medicines (NLEM) and in the World Health Organization’s (WHO) List of Essential Medicines (LEM). The rationality of the FDACs circulating in the city of Kinshasa were also evaluated based on the 2023 AWaRe classification. Methods: A cross-sectional and descriptive study was conducted between February and October 2025 in Kinshasa. For this purpose, fifty registered pharmacies open to the public were selected by systematic random sampling as the research sample. Data collection consisted of completing a data collection form after we had provided the pharmacies’ owners with the necessary explanations regarding the importance of the study and guaranteed their anonymity. Results: The controlled FDACs encountered comprised 27 specialties across 15 different formulations. Out of 15 formulations, 12 (80%) were included on the WHO list of non-recommended antibiotics and were not included in the DRC’s NLEM nor in the WHO’s LEM. Some had been withdrawn from the market in their countries of manufacture. Of the 15 FDACs evaluated for their rationality and compliance, the injectable FDACs presented problems related to the relevance and completeness of information contained on their packaging. On their primary packaging, there was a significant difference in the expiration dates of the powder and sterile water for injection contained in the combination pack, ranging from 6 to 36 months. Furthermore, the secondary packaging lacked data related to the sterile water for injection contained in the combination pack. In addition, several medications contained the same therapeutic combination. For injectable FDAC, for example, the combination Ceftriaxone-Sulbactam was represented by eight medications. For oral FDACs, the combination Sulfamethoxazole-Trimethoprim was represented by seven medications. Globally, 100% of these drug combinations originated from India. Conclusions: Fifteen varieties of FDACs were available in Kinshasa, most of which (80%) were unsuitable. It is important that public health authorities address this situation and develop stricter guidelines for granting marketing authorizations, particularly for FDACs. Full article

Injection molding has been used for many years in the fabrication of thermoplastic parts with different complexities. With metal and ceramic injection molding, it is possible to realize at the end of the related process chain sintered metal and ceramic parts. Parts made from glass are rather seldom realized applying powder technology methods. This work describes the production of devices made from a commercial soda-lime glass applying the process chain of powder injection molding, covering the individual process steps like compounding, shaping, debinding, and sintering. In the first step, a binder consisting of polyethylene glycol (PEG) with different average molecular masses (4000, 8000, and 20,000 g/mol), polyvinyl butyral (PVB), and stearic acid (SA) were used for compounding new feedstocks with a solid load of 55 Vol% and 60 Vol%. As filler, a soda-lime glass with an average particle size of 6.1 µm, an almost symmetrical particle size distribution, a specific surface area of 0.78 m²/g, and a spherical morphology was applied. The measured equilibrium torque during compounding was low, with values between 2.5 and 5.5 Nm depending on the solid load and average molecular mass of the investigated PEG. All feedstock possessed a pseudoplastic flow behavior in the shear rate range between 10 and 3500 1/s. Small disk-shaped parts, as well as large cuboids and plates, were injection molded to a good quality. These green bodies were pre-debinded in water to remove the PEG, subsequently followed by thermal debinding to eliminate the remaining organic moieties. The concluding sintering in the temperature range between 660 and 680 °C delivered glass parts with huge density values close to 100% of the theoretical value, as measured by the Archimedes method. The principal feasibility of glass injection molding with a suitable feedstock system could be demonstrated successfully. Full article