Additional Material Research Articles

Comparative study of microstructural evolution and mechanical properties in friction stir processed, reinforced friction stir processed, and heat-treated reinforced friction stir processed Al composites

The development of friction stir welding (FSW) created the basic foundation for friction stir processing (FSP). This process entails refining the local microstructure and achieving the localised plastic deformation due to the stirring effect of the tool, which may involve adding additional filler material as required. The rotating tool involved in the process has a shoulder and pin responsible for heat generation for plastic deformation and localised mixing. The rotating tool is inserted and traversed on the desired surface, tailoring the material properties. The tool’s exposure to the surface causes localised plastic deformation and thermal gradient, and microstructural changes occur locally. The present investigation uses Friction Stir Processing (FSP) to fabricate an aluminium metal matrix composite. Recently, the use of aluminium alloy has been replaced by composites because of their increased mechanical and physical properties (specific properties). The experiment leads to manufacturing an aluminium metal matrix composite using aluminium oxide, boron carbide and commercially pure copper dust. Later, the effect of heat treatment on the respective metal matrix composite is studied. A comparative study among three different types of FSP techniques viz. FSP, Reinforced FSP, and Heat-treated Reinforced FSP have been performed. The tool revolution speed (RPM) and tool traverse speed of 400 RPM and 10 mm/min had been implemented, respectively. The T4 Heat-Treatment cycle was used during the current investigation. This investigative study was performed to analyse the changes in grain sizes and hardness values at the stir zone (SZ), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ) and on the base materials (BM) of the samples. The reinforced FSP metal matrix composite (MMC) showed an 81.26% increase in the micro-hardness value (HV) compared to the base metal. Further on analysing the microstructures, the reinforced FSP composite showed a 65.20% reduction in grain size. Moreover, the Heat-Treated sample showed an increase in the micro-hardness value by 99.8%.

Systematic review of the use of phase change material (PCM) in concrete and the fire performance of PCM in concrete

ABSTRACT The Mechanical properties of concrete significantly deteriorate when exposed to fire, with explosive spalling posing a major threat to structural integrity. This highlights the need for effective insulation systems to protect concrete structures in fire conditions. However, current insulation solutions are typically installed externally, requiring additional labour and materials. This review explores the potential of incorporating Phase Change Materials (PCMs) directly into concrete as an embedded insulation system. As a latent heat storage material, PCM offers promising fire-resistant properties, reducing the need for external insulation while improving the fire performance of concrete. This paper presents a bibliometric analysis and a systematic review of recent publications on the use of PCMs in concrete and their fire performance applications. One thousand two hundred and four publications retrieved from Scopus© and Web of Science databases were passed through the PRISMA flowchart to obtain a database of recent literature on the study area. The current trend of research shows a shift towards inorganic PCMs in concrete. There is a significant lack of studies on using inorganic and eutectic PCM in concrete for fire applications and existing studies show inorganic PCM can be a viable solution. Commercial availability and lack of synthesised encapsulated PCM were found to be barriers to research.

Mechanical properties and global warming potential predictions for high-performance concrete through machine learning models integrated with meta-heuristic algorithms

Recent developments in high-performance concrete (HPC) have made it a high-tech material with enhanced durability and properties, and it is a more ecological material with a longer life cycle. Conventional approaches to assessing HPC properties and environmental effects may lack precision in predicting the effects of additional cementitious materials. Adaptive Boosting Algorithm (ADA) and Stochastic Gradient Boosting (SGB) have emerged as promising approaches for predicting HPC properties and environmental effects, offering more accurate and efficient alternative methods. In this study, the ADA and SBG models have been employed to predict the two essential HPC mechanical properties, including compressive and tensile strengths (CS and TS) and Global Warming Potential (GWP) by coupling with meta-heuristic algorithms, namely Stadium Spectators Optimizer (SSO), Golden Jackal Algorithm (GJA), Brown-bear Optimization Algorithm (BOA), and Golf Optimization Algorithm (GOA)‎ for developing hybrid and ensemble prediction approaches. The study assessed the effectiveness of different models for predicting HPC properties and GWP by employing various metrics. The SGSBGG framework showcased remarkable precision and performance compared to other models in the prediction of CS, TS, and GWP. It outshone its counterparts by achieving the highest prediction accuracy, securing R2 values of 0.994, 0.994, and 0.995 for CS, TS, and GWP predictions, respectively. Additionally, it demonstrated unparalleled accuracy with the lowest modeling errors, registering an RMSE of 1.306 for CS, 0.097 for TS, and 4.469 for GWP. Despite the clear superiority of the SGSBGG model, it is noteworthy that the SGSO, as a hybrid model, delivered notably compatible results.

Biochars from waste as an additive material in anaerobic co-digestion: Characterization and application in batch and semi-continuous systems

The conversion of organic waste into energy through anaerobic digestion (AD) is a profitable and environmentally friendly strategy. Enhancing the process is crucial for optimizing and maximizing biogas and methane production. To achieve this, various strategies can be employed, such as anaerobic co-digestion (co-AD) and the use of biochar. Biochar aids in process stability, provides buffering capacity, mitigates inhibitory toxins, immobilizes microorganisms, facilitates microbial colonization, and accelerates electron transfer between microorganisms. This study aimed to produce biochar from different wastes and pyrolysis temperatures and to investigate its use as an additive material in the co-AD of fruit and vegetable waste (FVW) and laying chicken manure (LCM) in batch and semi-continuous systems. Thermogravimetric analysis (TGA) and differential scanning calorimetry were performed to determine the pyrolysis temperature for biochar production, defining temperatures of 450 and 550 °C. A biochemical methane potential (BMP) test was conducted in 120 mL reactors (working volume) with the addition of 10 g/L of biochar from FVW, LCM, and wood pruning waste (WPW). WPW450 biochar showed the highest fixed carbon content, rough surface, and deep porous structure, factors that contributed to a 28 % increase in methane production compared to the control. Semi-continuous tests were conducted in 50 L reactors (working volume) using a reduced dosage (1 g/L) of WPW450 biochar, providing process stability and better biogas quality, resulting in a 31 % increase in methane production. The reduction in biochar dosage did not negatively impact the semi-continuous system, which showed a 74 % higher methane yield compared to the batch system. The results of this study highlight the importance of biochar addition to increase methane production in the co-AD of FVW and LCM at different scales, as well as the study of different biomasses and temperatures for biochar production.

Morphological and molecular characterisation of Mordellistenapeloponnesensis Batten, 1980 (Coleoptera, Mordellidae), with first records from Italy and Turkey.

Mordellistenapeloponnesensis Batten, 1980, previously known from Cyprus and Greece, is reported from Italy and Turkey for the first time. The species is redescribed based on type specimens and additional material from its entire known distributional range. Eighteen DNA barcoding sequences of M.peloponnesensis from Greece, Cyprus, and Italy were generated, and genetic variability across the sampling localities was examined. Three mitochondrial haplotypes were detected within M.peloponnesensis. Specimens from mainland Italy share the same haplotype as those from Rhodes and Cyprus, whereas Sardinian specimens exhibit a distinct haplotype. The third haplotype is represented by one specimen from Cyprus. The DNA barcoding sequences of M.peloponnesensis were compared with those of the morphologically allied M.gemellata Schilsky, 1898, and M.pyrenaea Ermisch, 1966, to reveal the phylogenetic relationships between the species.

Some Aspects of Neutrosophic Set Theory

This article aims to introduce my work on constructing neutrosophic set theory. Neutrosophy is a new branch of mathematical systems proposed by Smarandache in 1995 as an extension of an intuitionistic fuzzy set according to three-degree membership functions. The new perspective of neutrosophic sets consists of two paths, the first path depends on the three degrees including the degree of truth-membership, degree of indeterminacy-membership, and degree of false-non-membership respectively, while the second path depends on the generated classical set by three types of neutrosophic sets and study the concepts of neutrosophic theory. In previous work, I Presented the concepts of neutrosophic sets including universal, empty, compliment, and subsets. I also explored neutrosophic operations and their properties, such as neutrosophic unions and neutrosophic intersections. In this article, I shall delve into additional materials and theorems related to these concepts and discuss neutrosophic and symmetric differences, including their properties. Furthermore, I shall present a generalization of De Morgan's theorem.

Environmental Outcomes of Reducing Medication Waste by Redispensing Unused Oral Anticancer Drugs

Medications are associated with substantial environmental outcomes, yet frequently end up being unused by patients. Waste-minimizing interventions, such as redispensing of quality-approved oral anticancer drugs remaining unused by patients at home, could reduce the environmental footprint of cancer treatment. To assess the environmental outcomes of redispensing quality-assured oral anticancer drugs and to explore how redispensing could be environmentally optimized. In this quality improvement study, a cradle-to-grave life cycle assessment was performed in the outpatient pharmacy of 4 Dutch hospitals, based on a prospective multicenter trial comprising 1071 patients with a clinical diagnosis of cancer and an active prescription for an oral anticancer drug stored at room temperature from February 1, 2021, to February 1, 2023, with a follow-up of 12 months per patient. Participants received prescribed oral anticancer drugs with additional quality-assurance materials (ie, seal bags and time-temperature indicators), so the pharmacy could redispense quality-assured drugs based on authenticity, appearance, remaining shelf life, and/or adequate storage. The estimated environmental outcomes avoided due to waste reduction (ie, production and transport and incineration of redispensed oral anticancer drugs) corrected for outcomes of process burdens (ie, quality assurance materials), quantified in 3 outcome measures: human health damage (disability-adjusted life-years), ecosystems damage (species × year), and climate change (kg of carbon dioxide equivalent [CO2-eq]) per patient per year. A volunteer sample of 1071 patients (median age, 70 years [IQR, 62-75 years]; 622 men [58.1%]) participated in the intervention. Redispensing oral anticancer drugs was initially associated with an environmental burden, mainly because of the high impact of time-temperature indicators. However, when quality-assurance materials were selectively used for temperature-sensitive oral anticancer drugs (ie, maximum storage temperature of 25 °C), redispensing was environmentally beneficial to human health and ecosystems, providing estimated climate benefits of 1.9 kg (95% CI, 1.4-2.6 kg) of CO2-eq per patient per year. In this quality improvement study, redispensing unused oral anticancer drugs was found to be a suitable strategy to reduce waste and improve environmental sustainability of cancer treatment after process optimization. Redispensing unused oral anticancer drugs could contribute to sustainability of cancer treatment through reduced costs and environmental outcomes.

Self-Study and Discussion Promote Students’ Science Learning

AbstractMany have investigated the effectiveness of teaching methods across different disciplines. In a previous study, we found the superior effectiveness of a two-part learning sequence consisting of self-study followed by discussion in humanities education. To examine the possibility of similar findings in science education, we compared that sequence with a traditional lecture–based teaching. Results indicate that self-study combined with discussion yields higher test scores, demonstrating its potential as a beneficial teaching strategy in science education. In Experiment 1, undergraduate students from various disciplines studied introductory biology under five different conditions: self-study and discussion, lecture and discussion, lecture and review, self-study and review, and self-study and review with additional learning materials. Results indicated that the self-study and discussion condition yielded higher test scores than both the lecture and discussion condition and the three review groups. There were no significant differences in scores among the three review groups. These results demonstrate that discussion is an effective learning method and that self-study enhances the benefits of discussion. In Experiment 2, which involved science and engineering majors, we successfully replicated the design of Experiment 1 using physics for the two discussion conditions: self-study or lecture. We also performed in-depth analyses of student interactions during the discussions. Among the two discussion groups, the self-study and discussion group exhibited more active and constructive engagement in sharing unknowns, leading to enhanced learning. These findings suggest that integrating self-study with discussion can significantly enhance learning outcomes in science education. This approach not only improves test performance but also fosters deeper student thinking. Thus, educators might consider adopting this method to create more interactive and effective learning environments in science courses.

Carcinoplaxmistio Ng & Mitra, 2019 (Crustacea, Decapoda, Goneplacidae): additional records and genetic differentiation of allied taxa.

The goneplacid crab, Carcinoplaxmistio Ng & Mitra, 2019, was originally described from West Bengal, India, in the northern Indian Ocean. Additional material of C.mistio from off Tamil Nadu in the southeast of India revealed a high degree of size-associated variation in the structures of the anterolateral tooth of the carapace, chelipeds, and male and female pleons. In addition to an in-depth morphological examination of C.mistio, this study also records the natural coloration of the species and conducts a genetic comparison (with mitochondrial COI and 16S rRNA genes) with its close relatives, C.haswelli (Miers, 1884) and C.purpurea Rathbun, 1914. Molecular comparison of C.mistio with its morphologically closest congener, C.haswelli from northern Australia and the western Pacific, corroborates their status as separate species. The genetic sequence of C.mistio, however, is similar to that of C.purpurea from the West Pacific, although these two species can easily be distinguished by distinct carapace and ambulatory leg characters. The present study provides some possible explanations for the genetic and morphological incongruence observed between C.mistio and C.purpurea and highlights the need for a detailed molecular study for Carcinoplax H. Milne Edwards, 1852, to appreciate the evolution of various morphological characters in the genus.

The Effect of Google-Mediated Collaborative Writing on English as a Second Language Students’ Global and Local Writing Features

In recent decades, web-based collaborative writing has become popular as a technical technique for improving collaboration. The study explored the effect of Google-mediated collaborative writing (henceforth GMCW) and face-to-face collaborative writing (henceforth FTFCW) on developing English as a Second Language (henceforth ESL) students’ global and local writing features (organization, development, cohesion, structure, vocabulary, and mechanics). Despite the emphasis English language instructors in Saudi universities place on writing skills, students still face challenges in achieving proficiency in writing. The study included 46 male students at level 3 from the Qassim University English Language Department. An experimental study was used, along with a post-questionnaire, as additional material to collect students’ perceptions. In addition to using the independent t-test to compare the mean in the post-test of the two groups, a paired t-test was used to compare the mean in the pre-test and post-test of the same group. The researcher used a two-by-two mixed ANOVA to examine how students’ global and local writing features (such as organization, development, and cohesion) changed when they collaborated face-to-face or via Google Docs. The results showed that the Google-mediated collaborative writing post-test mean was greater than face-to-face collaborative writing in all writing features, and the difference was statistically significant. The questionnaire revealed that Google-mediated collaborative writing raised confidence, encouraged teamwork, instructed students on how to engage in peer feedback, and increased their willingness to use Google Docs for further assignments. Google-mediated collaborative writing benefited students more in terms of their writing quality (organization, development, and cohesion) than their writing accuracy (mechanics and structure). Google-mediated collaborative writing did not pay attention to form (spelling, punctuation, or structure). In contrast, students’ perceptions of the global and local writing aspects of face-to-face collaborative writing negatively impacted organization, development, and cohesion. The face-to-face collaborative writing students focused more on the essay form (mechanics and structure) than on the content (organization, development, and cohesion).

Developing translational products for adapting evidence-based physical activity interventions in rural communities

The development and distribution of educational materials is a key strategy to support the implementation of evidence-based interventions (EBIs). Rural communities have higher rates of physical inactivity and face higher burden of many diseases that increased physical activity can prevent. To support the translation of a developed physical activity intervention for adults in micropolitan communities (10,000-50,000 people), called Active XXXX, the University of XXXX Prevention Research Center for Rural Health (PRC-RH) created a toolkit and supplemental resources designed to guide implementers through the implementation of the intervention. Through a community-engaged process, the PRC-RH underwent three phases of review and evaluation of the developed products. The first phase involved the Community Advisory Board from the pilot intervention, the second involved the PRC-RH State Advisory Board and public health practitioners from across the state, and the third involved micropolitan leaders and micropolitan health department staff. The feedback received through these three phases resulted in changes to the developed products to improve usability, readability, and clarity. The feedback also resulted in the development of additional materials to further support the implementation of the intervention. The success the PRC-RH experienced in the review process can be attributed to the strong, established partnerships with practitioners across the state who represented a variety of community roles and organizations. The developed materials can be used to improve physical activity rates in rural and micropolitan communities, in turn reducing chronic diseases and improving the quality of life for rural residents.

Effect of Heat Input on Microstructure and Microhardness in WAAM

Experiments were carried out for WAAM of samples using electric arc and additive material in the form of solid wire grade G3Si1. The layers were built-up with one transition each. Metallographic macro- and microsections were made from the obtained samples. The macro- sections are used to determine the locations of microhardness measurements. The microsections were used to measure the microhardness and to illustrate the microstructure. The analysis of the obtained results shows that the heat input and the interlayer temperature are of crucial importance for the obtained mechanical characteristics of the built-up samples. The microstructure of the obtained layers varies along the height of the built-up samples thus witnessing for the thermal treatment occurring in each layer except the last one as a result of applying the subsequent layers.

Make Some Noise: Generating Data from Imperfect Factor Models

Researchers simulating covariance structure models sometimes add model error to their data to produce model misfit. Presently, the most popular methods for generating error-perturbed data are those by Tucker, Koopman, and Linn (TKL), Cudeck and Browne (CB), and Wu and Browne (WB). Although all of these methods include parameters that control the degree of model misfit, none can generate data that reproduce multiple fit indices. To address this issue, we describe a multiple-target TKL method that can generate error-perturbed data that will reproduce target RMSEA and CFI values either individually or together. To evaluate this method, we simulated error-perturbed correlation matrices for an array of factor analysis models using the multiple-target TKL method, the CB method, and the WB method. Our results indicated that the multiple-target TKL method produced solutions with RMSEA and CFI values that were closer to their target values than those of the alternative methods. Thus, the multiple-target TKL method should be a useful tool for researchers who wish to generate error-perturbed correlation matrices with a known degree of model error. All functions that are described in this work are available in the fungible R library. Additional materials (e.g., R code, supplemental results) are available at https://osf.io/vxr8d/.

Development of a technological solution aimed at improving the consumer properties of a new fish culinary product enriched with chondroitin sulfate of thorny skate

The paper presents the results of developing a fish culinary product (thorny skate meat mixed with Atlantic cod meat, baked with potatoes and mushrooms in a cream sauce) enriched with chondroitin sulfate contained in the meat and cartilage of the wings of thorny skate. Atlantic cod, more familiar to the Russian consumer and successfully complementing the skate's meat with amino acid composition, has been chosen as an additional fish raw material. Thorny skate belongs to the underutilized fishing facilities of the Northern Basin. The meat of its wings contains up to 1.5 % urea, which worsens its organoleptic properties. To solve this problem, it was previously proposed to use short-term preliminary heat treatment (PHT) of skate's wings by blanching them in water at a temperature from 93 to 96 °C for 1–3 minutes, which guarantees a fourfold decrease in the mass fraction of urea in the meat, relative to the initial content, below the organoleptic perception of the consumer. PHT also facilitates the cutting of the skate's meat. The formulation and technology of a combined fish culinary product is proposed, packaged and completely ready for consumer's use. To prolong the shelf life up to 120 days, it is proposed to subject the product to shock freezing with subsequent storage at a temperature no higher than minus 18 °C. To solve the problem of delamination of cream sauce during storage and to improve the consumer properties of the product, an experimentally based technological solution is proposed – the introduction of oat flour in the composition of the sauce formulation as a thickener and structure-forming agent in an amount of 3.5 % per total mass of sauce.

Hydroxyapatite-polymer composites with tannin as a chelating agent: crystal structure and mechanical properties

Hydroxyapatite is the main minerals in the bone as a biomaterial. The synthesis of hydroxyapatite requires additional materials to improve its mechanical properties. This research aimed to observe the ability of tannins as a chelating agent in hydroxyapatite synthesis. Hydroxyapatite was synthesized from Ca(OH)2, (NH4)2HPO4, Ca(OH)2, H3PO4, and tannin as chelating agents with precipitation method. Hydroxyapatite made from calcium and phosphate as a precursor and control the pH was 12 with the addition of Sodium Hydroxide. Then, added tannin and stirrer about 1 hour. The precipitate was dried in oven at 40°C for Hydroxyapatite using H3PO4 precursor. All the samples were characterized using FTIR, XRD, SEM and Hardness tester. Two compounds (calcium carbonate and hydroxyapatite) were obtained by using XRD analysis. The crystal size of the hydroxyapatite of 15-27 nm and hydroxyapatite-tannin of 10-29 nm. The SEM results show the surface morphology of hydroxyapatite was obtained as agglomerates or clumping. Hydroxyapatite-tannin was obtained with particle size in fields from 0.1-0.4 µm. The Hardness Tester received an average value was 28.36 N and 27.81 N for hydroxyapatite and 34.43 N dan 33.92 N for hydroxyapatite-tannin. Tannin acts as a chelating agent in the synthesis process of hydroxyapatite by the precipitation method.

Resistance Welding of Thermoplastic Composites, Including Welding to Thermosets and Metals: A Review.

This review paper presents the current progress in the development of resistance welding techniques for thermoplastic composites, with a particular emphasis on their application in hybrid joints, such as those involving thermosetting composites and metals. Resistance welding, a fusion bonding method, offers significant advantages over adhesive bonding and mechanical joining by eliminating the need for additional adhesive materials and enabling integration into automated manufacturing processes. The study highlights the unique benefits of resistance welding, including lower energy consumption compared to other methods and its compatibility with automated manufacturing, which can reduce production costs by up to 40%. Key findings from the literature indicate that resistance welding is particularly effective in achieving strong, durable joints for complex and large structures, such as those used in the aerospace industry. The review also identifies the main challenges associated with resistance welding, including temperature control, current leakage in carbon-fiber-reinforced polymers, and potential corrosion when using metal meshes. To address these challenges, various strategies are discussed, including surface treatments, the use of nanocomposites, and the integration of carbon nanotubes. The review concludes by emphasizing the need for further research to optimize welding parameters and to develop non-destructive testing methods for industrial applications, ensuring the reliability and long-term performance of welded joints.

Evolution of the Principle of International Responsibility to Protect (R2P) Civilians in International Law

The application of the principle of the responsibility to protect (R2P) civilians has not helped to consolidate this principle to the extent that it has contributed to surrounding it with flaws and to the formation of additional contentious material that has contributed to renewed debate over the feasibility and legitimacy of the use of force on humanitarian basses. Whilst the adoption of a new principle entitled "Responsible Sovereignty" that presupposes a balance between sovereignty and intervention, and after benefiting from the expansion of the concept of threat to international peace and security and the elaboration of a conditional controls that must be respected, for the use of force for humanitarian motives derived from the theory of just war, the international practice of this principle has not lived up to the level of ambitions, as the dilemma of selectivity and the exploitation of intervention as a pretext by the major powers remained unresolved.

A Systematic Evaluation of Design Freedoms and Restrictions of Lattice Structures Used as Interlock Bonds

Additive manufacturing provides new possibilities in product design compared to traditional manufacturing processes. Particularly additive material extrusion offers the freedom to combine multiple materials in a single component without additional steps. However, combining multiple materials often leads to reduced adhesion, which can hinder the creation of high-strength designs. This issue can be largely mitigated using the geometric freedom of additive manufacturing to produce interlocking structures. This publication investigates the use of lattice structures as interlocking bonds in multi-material applications. The aim is to aid the design of suitable lattice structures by collecting geometric freedoms of lattices, application requirements, and manufacturing constraints, for this information to be used in suitable designs in the future. Initially, the general design freedoms of lattice structures are compiled and explained. Subsequently, these design freedoms are narrowed down based on the specific requirements for interlocking bonds and the limitations imposed by geometry and material combinations during manufacturing. The publication concludes with design recommendations that can be used as the basis for interlock bonds. Suitable lattice designs should aim for high interconnectivity, interconnected porosity, and a high number of similar strut structures, all the while maintaining low dimensions in the interface direction.

Zinc and chitosan-enhanced β-tricalcium phosphate from calcined fetal bovine bone for mandible reconstruction.

Mandibular defects pose significant challenges in reconstructive surgery, and scaffold materials are increasingly recognized for their potential to address these challenges. Among various scaffold materials, Beta-tricalcium phosphate (β-TCP) is noted for its exceptional osteogenic properties. However, improvements in its biodegradation rate and mechanical strength are essential for optimal performance. In this study, we developed a novel β-TCP-based scaffold, CFBB, by calcining fetal bovine cancellous bone. To enhance its properties, we modified CFBB with Chitosan (CS) and Zinc (Zn), creating three additional scaffold materials: CFBB/CS, CFBB/Zn2+, and CFBB/Zn2+/CS. We conducted comprehensive assessments of their physicochemical and morphological properties, degradation rates, biocompatibility, osteogenic ability, new bone formation, and neovascularization both in vitro and in vivo. Our findings revealed that all four materials were biocompatible and safe for use. The modifications with CS and Zn2+ significantly improved the mechanical strength, osteogenic, and angiogenic properties of CFBB, while concurrently decelerating its resorption rate. Among the tested materials, CFBB/Zn2+/CS demonstrated superior performance in promoting bone regeneration and vascularization, making it a particularly promising candidate for mandibular reconstruction. The CFBB/Zn2+/CS scaffold material, with its enhanced mechanical, osteogenic, and angiogenic properties, and a controlled resorption rate, emerges as a highly effective alternative for the repair of oral mandible defects. This study underscores the potential of combining multiple bioactive agents in scaffold materials to improve their functionality for specific clinical applications in bone tissue engineering.

Evaluation of Different ZX Tensile Coupon Designs in Additive Manufacturing of Amorphous and Semi-Crystalline Polymer Composites

The layer-by-layer deposition of molten polymer filament in fused deposition modeling (FDM) has evolved as a disruptive technology for building complex parts. This technology has drawbacks such as the anisotropic property of the printed parts resulting in lower strength for parts printed in the vertical Z direction compared with the other two planes. In this manuscript, we attempt to address these challenges as well as the lack of standardization in sample preparation and mechanical testing of the printed parts. The paper focuses on process parameters and design optimization of the ZX build orientation. Type I tensile bars in ZX orientation were printed as per the ASTM D638 standard using two (2B) and four (4B) tensile bar designs. The proposed design reduces material loss and post-processing to extract the test coupons. Printing a type I tensile bar in the ZX orientation is more challenging than type IV and type V due to the increased length of the specimen and changes in additional heat buildup during layer-by-layer deposition. Three different polymer composite systems were studied: fast-crystallizing nanofiller-based high-temperature nylon (HTN), slow-crystallizing nanofiller-based polycyclohexylene diethylene terephthalate glycol-modified (PCTG), and amorphous carbon fiber-filled polyetherimide (PEI-CF). For all the polymer composite systems, the 2B showed the highest strength properties due to the shorter layer time aiding the diffusion in the interlayers. Further, rheological studies and SEM imaging were carried out to understand the influence of the two designs on fracture mechanics and interlayer bonding, providing valuable insights for the field of additive manufacturing and material science.