Extrusion Technique Research Articles

On the Hydrodynamic and Structural Performance of Thermoplastic Composite Ship Propellers Produced by Additive Manufacturing Method

In the marine industry, the search for sustainable methods, materials, and processes, from the product’s design to its end-of-life stages, is a necessity for combating the negative consequences of climate change. In this context, the lightening of products is essential in reducing their environmental impact throughout their life. In addition to lightening through design, lightweight materials, especially plastic-based composites, will need to be used in new and creative ways. The material extrusion technique, one of the additive manufacturing methods, is becoming more widespread day by day, especially in the production of objects with complex forms. This prevalence has not yet been reflected in the marine industry. In this study, the performances of plastic composite propellers produced by the material extrusion technique is investigated and discussed comparatively with the help of both hydrodynamic and structural tests carried out in a cavitation tunnel and mechanical laboratory. The cavitation tunnel test and numerical simulations were conducted at a range of advance coefficients (J) from 0.3 to 0.9. The shaft rate was kept at 16 rps. The thrust and torque data were obtained using the tunnel dynamometer. Digital pictures were taken to obtain structural deformation and cavitation dynamics. The structural performance of the propellers shows that an aluminum propeller is the most rigid, while a short carbon fiber composite propeller is the most flexible. Continuous carbon fiber composite has high strength and stiffness, while continuous glass fiber composite is more cost-effective. In terms of the hydrodynamic performance of the propellers, flexibility reduces the loading on the blade, which can result in thrust and torque reduction. Overall, the efficiency of the composite propellers was similar and less than that of the rigid aluminum propeller. In terms of weight, the composite carbon propeller containing continuous fiber, which is half the weight of the metal propeller, is considered as an alternative to metal in production. These propellers were produced from a unique composite consisting of polyamide, one of the thermoplastics that is a sustainable composite material,, and glass and carbon fiber as reinforcements. The findings showed that the manufacturing method and the new composites can be highly successful for producing ship components.

High-temperature solar energy absorption enhancement of mixed-phase core–shell spherical Al-based composite particles

This study focuses on the development of heat transfer/thermal energy storage particles for direct irradiation solid particle solar receivers to improve the efficiency by enhancing solar absorption, thermal stability, thermal storage property, and mechanical strength. A novel dry-mix extrusion technique was adopted to synthesize Al-based core–shell composite particles. The research shows that particles coated with 5.5 wt% mixed-phase metallic compounds maintain over 90 % solar absorptivity after 300 h at 1200°C, 600-1200°C thermal cycling, and wear tests, with an absorptivity change negligible (±2.20 %) and a mass loss of less than 0.053 g. The cost of the particles is below 1.5€/kg with good flowability, compressive strength up to 398.6 MPa, and an energy density as high as 2675.3 kJ/(m3·K). Monte-Carlo finite element numerical results found that the absorption efficiency of a composite particle curtain with a thickness of 0.02 m and a volume fraction of 0.05 increased by 169.6 % over the original ones. The particles can operate for extended periods at higher temperatures or harsh conditions to improve energy conversion efficiency, extend service life, and reduce maintenance requirements. It demonstrates the potential application value in the field of thermal energy absorption and storage, providing highly promising candidates for future high-temperature solar thermal applications.

Multi-well plate-based versatile platform for online fabricating alginate hydrogel microspheres and in-situ 3D cell culture

BackgroundHydrogel microspheres with monodisperse and homogeneous dimensions have potential application in the field of three-dimensional (3D) cell culture due to its ability to provide a similar microenvironment. Currently, alginate hydrogel microspheres (AHMs) have received much attention due to the favorable properties of alginate such as biocompatibility, inexpensiveness, nontoxicity, and biodegradability. The fabrication methods of AHMs mainly include extrusion, electrostatic dripping and microfluidic chip techniques. These current methods suffer trade-offs between operational complexity, fabrication cost and practical application. ResultsWe proposed a novel and versatile multi-well plate-based platform for online fabricating AHMs and in-situ 3D cell culture. The AHMs could be easily fabricated based on gravity-driven gelation combined with our recently developed bent-capillary-centrifugal-driven (BCCD) system. Ca-EDTA complex was used as Ca2+ source for crosslinking reaction of the alginate chains. The whole preparation process of AHMs included four steps: emulsification, pre-gelation, spontaneous demulsification and further solidification. The gravity-driven hydrogel microsphere gelation could produce the AHMs with good sphericity (Φ = 0.96) and monodispersity (PDI% = 0.94 %). The rapid drug susceptibility testing and single-cell encapsulation in the AHMs were well demonstrated. It also provided a novel in-situ 3D cell culture strategy, which demonstrated more than 85 % cell viability in practice. SignificanceThe proposed platform avoided the complex and laborious microfabrication. Moreover, cell-encapsulated AHMs could be directly produced in the multi-well plate, which could facilitate the subsequent cultivation and observation. It is expected to be a versatile in-situ 3D cell culture tool in the fields of biomedicine and tissue engineering.

Grain recovery facilitated low-angle grain boundaries and texture for high-performance BiSbTe alloys

Low-angle grain boundaries (LAGBs) bring an effective scattering of phonons while maintaining a weak effect on charge carrier transport, which could be utilized for enhancing the thermoelectric performance of solid materials. In the Bi2Te3-based materials fabricated by hot extrusion (HE) technique, however, the formation of the LAGBs is evitably accompanied by severe recrystallization, resulting in texture loss and hindering further zT improvement. Here, we demonstrate a feasible strategy utilizing the grain recovery to maintain dense LAGBs with high grain orientation by the optimized HE technique. As a result, a low thermal conductivity of about 1 W m−1 K−1 and a high power factor of 4.2 mW m−1 K−2 are achieved at 300 K for p-type Bi0.5Sb1.5Te3 alloys, leading to a high room-temperature zT of 1.3. Further, with a decent flexural strength of 25.3 MPa, a 23-pair TE cooling module with the dice dimensions of 0.63 × 0.63 × 1.00 mm3 is assembled, which exhibits a maximum temperature difference of 87.8 K at a hot-side temperature Th of 350 K. These results highlight the important role of grain-recovery manipulation in simultaneously optimizing the thermal and electrical properties toward high-performance Bi2Te3-based TE materials.

Roadmap for Power Generation of Industrial Hot Extruded Bi2Te3-Based Thermoelectric Device in Real-World Heat Sources.

Recovering waste heat through thermoelectric (TE) technology is critical for enhancing energy efficiency. However, commercial devices often require n- and p-type thermoelectric units to have similar cross-sectional areas and conductivities, complicating optimization of their figure of merit (ZT). Moreover, real-world heat sources are not constant temperature sources, and only heat flux can be measured. Given these constraints, selecting appropriate parameters for TE devices to maximize their output power for specific heat sources is of significant scientific and practical importance. In this work, we studied a series of n- and p-type Bi2Te3-based TE materials, prepared using commercial hot extrusion techniques, with average conductivities of approximately 650 S cm-1, 820 S cm-1, 1050 S cm-1, and 1300 S cm-1 over the temperature range of 50-250 °C. These materials were assembled into four different thermoelectric devices (HE1, HE2, HE3, and HE4). Finite element simulations for devices HE1, HE2, HE3, and HE4 (TE leg: 1.4 mm × 1.4 mm × 1.6 mm, device area: 40 mm × 40 mm) showed maximum power densities of 3953.5 W m-2 and 1300.8 W m-2 at 67,000 W m-2 and 33,500 W m-2 heat fluxes, respectively. The fabricated devices achieved maximum power densities of 2907.1, 3014.0, 2910.9, and 2525.4 W m-2 at 67,000 W m-2 heat flux, with discrepancies attributed to interface thermal resistance. Based on these findings, we have plotted output performance roadmaps for TE devices with different average electrical conductivities under various heat flux densities (67,000 W m-2 and 33,500 W m-2) as functions of external load and TE leg height. These roadmaps enable rapid design of TE devices tailored to specific external heat source conditions and cost requirements, thereby maximizing waste heat recovery. This study's use of electrical conductivity as a performance indicator for final device output power density offers direct guidance for practical waste heat recovery applications.

FRESH 3D printing of zoledronic acid-loaded chitosan/alginate/hydroxyapatite composite thermosensitive hydrogel for promoting bone regeneration

The aim of this study was to develop a composite thermosensitive hydrogel for bone regeneration applications. This hydrogel consisted of chitosan, alginate and hydroxyapatite, and was loaded with zoledronic acid as a model drug. The feasibility of three-dimensional (3D) printing of the thermosensitive hydrogel using the extrusion based technique was investigated. The 3D printing technique called Freeform Reversible Embedded Suspended Hydrogel (FRESH) printing was employed for this purpose. To characterize the composite hydrogels, several tests were conducted. The gelation time, rheological properties, and in vitro drug release were analyzed. Additionally, the cell viability test on human osteosarcoma MG-63 cells for the composite hydrogel was assessed using an MTT assay. The results of the study showed that the zoledronic acid-loaded composite thermosensitive hydrogel was successfully printed using the FRESH 3D printing technique which was not possible otherwise i.e., by using traditional 3D printing techniques. Further examination of the printed constructs using a Scanning Electron Microscope revealed the presence of porous and layered structures. The gelation times of the composite thermosensitive hydrogel was determined to be 10 and 20 min, respectively for scaffolds with and without HA, indicating the successful formation of the gel within a reasonable time to the FRESH technique. The flow behavior of the hydrogel was found to be pseudoplastic, following a non-Newtonian flow pattern with Farrow’s constant (N) values of 1.708 and 1.853 for scaffolds with and without hydroxyapatite, respectively. In terms of drug release, scaffolds prepared with and without hydroxyapatite reached nearly 100% of zoledronic acid release in 360 h and 48 h, respectively. The cell viability test on human osteosarcoma MG-63 cells using MTT assay has shown increased cell viability % in the case of composite hydrogel, indicating biocompatibility of the scaffold. Overall, this study successfully developed a composite thermosensitive hydrogel loaded with zoledronic acid for bone regeneration applications and was 3D printed using the FRESH 3D printing technique. The results of this study provide valuable insights into the potential use of this composite hydrogel for future biomedical applications.

A novel solvent-extruded tacrolimus-eluting suture for attenuated inflammation and scarring in skin repair

This study aimed to design an absorbable suture that locally delivers the immunosuppressive agent, tacrolimus (FK506), to attenuate scar tissue formation by modulating inflammation. As the suture degrades, it releases FK506 directly into the repair site. The poly (l-lactide-co-caprolactone) (PLLA-PCL) polymer and 0.2 % wt FK506 were co-extruded using a solvent extrusion technique to generate the drug-eluting sutures. The properties of the generated sutures were assessed regarding FK506 release in vitro, wound closure in an in vivo murine model, murine skin histology for structural and inflammatory markers, and mechanical strength of both sutures and healed murine skin. The generated suture consistently released FK506 at ≤10 ng/day rates. Following annealing, the sutures retained 60 % of their anticipated tensile strength, exhibiting enhanced ductility. The histological examination and in vivo murine study indicated that wounds treated with FK506-eluting PLLA-PCL sutures produced a thinner epidermal layer, enhanced integrin β4 expression, increased keratinocyte presence, attenuated inflammation, and reduced scarring, demonstrating healed tissue improvements compared with those treated with the placebo, poly (glycolic-co-caprolactone) (PGCL), sutures. Mechanical evaluations of healed tissue indicated that drug-PLLA-PCL sutures did not reduce the mechanical strength of the skin compared to placebo PGCL sutures. The FK506-eluting PLLA-PCL sutures show promising results in advancing wound healing by offering targeted drug delivery. This innovative method can improve wound healing and provide a streamlined approach to scar management. Continued research, optimization, and broad-scale studies are needed to refine the manufacturing process and ensure that the properties of the suture meet clinical requirements.

Microstructure and Properties of 7050-T74 Aluminum Alloys with Different Zn/Mg Ratios

Aluminum alloy 7050-T74 with varying zinc-to-magnesium (Zn/Mg) mass fractions was synthesized using melt casting and hot extrusion techniques. This study investigated the influence of different Zn/Mg ratios on the microstructure, mechanical properties, and corrosion resistance of the alloy. Light microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile testing, and corrosion testing were employed as analytical methods. The findings indicate that as the Zn/Mg ratio increases from 2.36 to 3.84, the proportion of low-angle boundaries (LABs) within the alloys initially rises and then decreases, achieving a balance between high strength and favorable elongation. Specifically, at a Zn/Mg ratio of 2.72, the alloy exhibits a tensile strength of 641 MPa, a yield strength of 609 MPa, and an elongation of 10.1%. Additionally, increasing the Zn/Mg ratio to 2.90 slightly reduces intergranular corrosion resistance while enhancing exfoliation corrosion resistance.

Catheter Exchange With Elongation of Tunnel (CEET) Procedure-A Novel Technique for Cuff Extrusion of Tunneled Dialysis Catheter: Surgical Experience and Early Outcomes.

Cuff extrusion of tunneled dialysis catheter (TDC) leads to catheter dysfunction, leading to loss of vascular access and the need for new catheter. Definitive management is to remove TDC and reinsert new catheter by new venous puncture and tunnel, which may not be possible in all cases. The study evaluated the surgical experience and early outcomes of a novel "Catheter Exchange with Elongation of Tunnel (CEET)" procedure for cuff extrusion. The retrospective study included all cases of hemodialysis with TDC with partial or complete cuff extrusion and excluded complete catheter dislodgement, tunnel infection, or any catheter related infection. All patients also underwent the CEET procedure under fluoroscopy guidance, and the clinical details and outcomes were analyzed. Eleven cases of TDC cuff extrusion underwent the CEET procedure of which three (27.2%) had previous and four (36.4%) had partial cuff extrusion, and seven cases (63.6%) had short tunnel length, which likely predisposed to cuff extrusion. CEET procedure was successful in 10 cases (success rate 90.1%) with desired position of catheter tip and good blood flow. Study population was divided into early and late cuff extrusion (≥1 month). Short tunnel length was associated with late extrusion (p = 0.05), whereas premature removal of TDC anchor sutures was associated with early cuff extrusion (p = 0.04). CEET procedure is a successful alternative technique for correction of cuff extrusion of TDC with good success rate. Premature removal of anchor sutures was associated with early cuff extrusion, whereas short tunnel length was associated with late cuff extrusion.

Comparative efficiency of Geotrichum candidum microcapsules prepared with alginate and in combination with other polymers: In vitro evaluation

Microencapsulation is utilized to protect probiotics, such as Geotrichum candidum, ensuring their survival, stability, and targeted release. The encapsulation efficiency depends on factors such as the type and concentration of the polymers and the encapsulation method. In this study, G. candidum was encapsulated using alginate (Alg) combined with starch (AlgS) or xanthan (Alg-X) and coated with chitosan aand chitosan nanoparticles (AlgC, Alg-S-C, Alg-X-C, Alg-CN, Alg-S-CN, and Alg-X-CN) using a simple extrusion technique. The structural characteristics and surface morphology of the microcapsules were analyzed using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Encapsulation efficiency (EE) and pH and temperature tolerances were assessed using in vitro assays. SEM results showed that the Alg-CN microcapsules were notably spherical and smooth, in contrast to the irregular and rough textures of the uncoated forms. Notably, Alg-CN exhibited the highest EE (99.3 %), followed by Alg-C (96.6 %) and Alg-X-CN (96.03 %). Moreover, chitosan-coated microcapsules, particularly Alg-CN, demonstrated superior viability at various pH levels and after exposure to 60 °C, along with extended shelf life at room temperature and 4 °C. These findings suggest that a 2 % alginate and 0.4 % chitosan combination is optimal for preserving G. candidum's viability in various applications.

Designing Hand Orthoses: Advances and Challenges in Material Extrusion

The intricate structure of human hands requires personalized orthotic treatments, especially with the growing aging population’s demand for accessible care. While traditional orthoses are effective, they face challenges of cost, customization time, and accessibility. Additive manufacturing, particularly material extrusion (MEX) techniques, can effectively address challenges in orthotic device production by enabling automated, complex, and cost-effective solutions. This work aims to provide engineers with a comprehensive set of design considerations for developing hand orthoses using MEX technology, focusing on applying design for additive manufacturing principles, to enhance rehabilitation outcomes. This objective is achieved by establishing design requirements for hand orthoses, reviewing design choices and methodologies across conventional and state-of-the-art MEX-based devices, and proposing an innovative approach to orthotic design. Hand orthosis design requirements were gathered through workshops with occupational therapists and categorized into engineer-, medical-, and patient-specific needs. A review of 3D-printed hand orthoses using MEX analyzes various design approaches, providing insights into existing solutions. The study introduces a modular design concept aimed at improving rehabilitation by enhancing customizability and functionality. It highlights the potential of MEX for creating personalized, cost-effective orthoses and offers recommendations for future research, to optimize designs and improve patient outcomes.

Polymer microsphere inks for semi-solid extrusion 3D printing at ambient conditions

Extrusion-based 3D printing methods have great potential for manufacturing of personalized polymer-based drug-releasing systems. However, traditional melt-based extrusion techniques are often unsuitable for processing thermally labile molecules. Consequently, methods that utilize the extrusion of semi-solid inks under mild conditions are frequently employed. The rheological properties of the semi-solid inks have a substantial impact on the 3D printability, making it necessary to evaluate and tailor these properties. Here, we report a novel semi-solid extrusion 3D printing method based on utilization of a Carbopol gel matrix containing various concentrations of polymeric microspheres. We also demonstrate the use of a solvent vapor-based post-processing method for enhancing the mechanical strength of the printed objects. As our approach enables room-temperature processing of polymers typically used in the pharmaceutical industry, it may also facilitate the broader application of 3D printing and microsphere technologies in preparation of personalized medicine.

Hot extrusion, tensile deformation behavior and deformation mechanism analysis of a wrought superalloy with a high γ′ phase volume fraction of 64 %

A hundred kilograms of GH4975 extrusion bar, featuring fine equiaxed grains, were successfully fabricated using electron beam smelting layer solidification(EBSL) and hot extrusion techniques. Subsequent analysis focused on the microstructure and tensile properties of the extruded bar. The study also delved into the influence of temperature on tensile deformation behavior and mechanisms of the alloy after standard heat treatment(SHT). The results revealed uniformity in precipitated phase size and morphology across the extruded bar, with grain size being the largest at the center and smallest at the edge. Tensile tests conducted at 20 °C and 650 °C show an obvious work hardening phenomenon, and the deformation mechanism is dominated by APB coupled dislocation pairs shearing. With the increase of deformation temperature, the work-hardening phenomenon gradually weakens, and SFs emerge as the primary deformation mechanism at 750 °C. As the deformation temperature further rises, cross slip, Orowan bypass and dislocation climbing gradually dominate. The fracture mode changes from brittle fracture to ductile and brittle mixed fracture, and ultimately to brittle fracture. Compared with the traditional preparation method, the hundred kilograms of GH4975 extrusion bar prepared by this technology still show better mechanical properties.

Performance of Recycled Opaque PET Modified by Reactive Extrusion

A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate (PC) blend. The chemical modifications introduced during reactive extrusion were confirmed using differential scanning calorimetry (DSC) and rheological dynamic analysis (RDA). For the quantification of the fracture parameters, an instrumented pendulum impact testing machine was used using specimens in SENB configuration. The structural modifications generated during reactive extrusion promote an increase of between 16 (REx-rPET-O) and 20% (rPET-O/PC) in the stress-intensity factor (KQ) compared to unmodified rPET-O. The most significant differences between both modifications are registered in the “specific work of fracture” (wf) (alternative parameter to the standardized impact strength), where an increase of 61% is reached for the case of rPET-O/PC and only 11% for REx-rPET-O. This trend can be attributed to the type of reactive modification that is generated, namely chain branching (REx-rPET-O) vs. the generation of a random copolymer “in situ” (rPET-O/PC). This copolymer decreases the crystallization capacity and degree of crystalline perfection of rPET-O, promoting an increase in the critical hydrostatic stress conditions for the generation of crazing and crack propagation.

Three-Dimensional Printing Limitations of Polymers Reinforced with Continuous Stainless Steel Fibres and Curvature Stiffness

This study investigates the printability limitations of 3D-printed continuous 316L stainless steel fibre-reinforced polymer composites obtained using the Materials Extrusion (MEX) technique. The objective was to better understand the geometric printing limitations of composites fabricated using continuous steel fibres, based on a combination of bending stiffness testing and piezoresistive property studies. The 0.5 mm composite filaments used in this study were obtained by co-extruding polylactic acid (PLA), with a 316 L stainless steel fibre (SSF) bundle. The composite printability limitations were evaluated by the printing of a series of ’teardrop’ shaped geometries with angles in the range from 5° to 90° and radii between 2 and 20 mm. The morphology and dimensional measurements of the resulting PLA-SSF prints were evaluated using μCT scanning, optical microscopy, and calliper measurements. Sample sets were compared and statistically examined to evaluate the repeatability, turning ability, and geometrical print limitations, along with dimensional fluctuations between designed and as-printed structures. Comparisons of the curvature bending stiffness were made with the PLA-only polymer and with 3D-printed nylon-reinforced short and long carbon fibre composites. It was demonstrated that the stainless steel composites exhibited an increase in bending stiffness at smaller radii. The change in piezoresistance response of the PLA-SSF with load applied during the curvature bending stiffness testing demonstrated that the 3D-printed composites may have the potential for use as structural health monitoring sensors.

Adaptive reuse of waste plastic as binders in composites for sustainable construction

Effective and efficient handling of solid waste remains a significant issue, particularly in low- and middle-income countries, and densely populated urban areas. Waste plastic is identified as a major contributor to solid waste streams. This study highlighted the viable reuse of waste Linear low-density polyethylene (LLDPE) plastic as a binder and full replacement for cement in composite blocks. An extrusion technique was adopted to melt the plastic and mix it with the sand fillers to create a homogenous waste plastic binder composite block. Composite block samples were produced at various mixture ratios of 1:1, 1:2, and 1:3 with waste plastic or cement as binder and sand as filler. The composite samples' compressive strength, flexural strength, tensile strength, UPV, thermal conductivity, skid resistance, Cantabro mass loss, and morphology were investigated. In addition, the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis of the composites were carried out. The results showed that composite blocks containing waste LLDPE plastic as binder exhibited lower compressive strength, higher flexural strength, and tensile strength, better thermal insulation, and abrasion resistance compared to composite blocks containing cement as binder. Meanwhile, the cement binder composite gave better skid resistance when the surface was wet than the waste plastic binder composite. However, the waste LLDPE plastic composite mixes considered gave compressive strength above 5 N/mm2, which is the minimum requirement for building bricks according to BS 3921: 1985.

Improving mechanical and electrical contact performance of silver based electrical contact material reinforced by flower spherical zinc oxide loaded with silver nanoparticles

Flower spherical ZnO loaded with Ag nanoparticles was synthesized by hydrothermal method. Ag/ZnO electrical contact materials were prepared by powder metallurgy combined with hot extrusion technique. During the hydrothermal reaction, Ag nanoparticles entered the interlayer gaps of flower spherical ZnO and uniformly deposited on its surface. The tensile mechanical test results indicate that the Ag/ZnO electrical contact materials prepared by ZnO, Ag@ZnO(75 wt%) and Ag@ZnO(50 wt%) exhibited elongations of 6.8 %, 13.8 % and 12.1 %, respectively. This result indicates that appropriate loading of Ag nanoparticles on flower spherical ZnO could significantly improve the mechanical properties of Ag/ZnO electrical contact materials. The contact resistance of electrical contact materials significantly affects their temperature rise characteristics. During 20, 000 cycles process, Ag/ZnO electrical contact material prepared by Ag@ZnO(50 wt%) exhibited the lowest temperature rise of 6.33 K under the conditions of DC 36 V/10 A. Considering both mechanical and electrical contact performance, Ag/ZnO electrical contact materials prepared by Ag@ZnO(50 wt%) exhibited the optimum overall performance.

Photocurable biomaterials labeled with luminescent sensors dedicated to bioprinting

In the present study, we focused on the development and characterization of formulations that function as biological inks. These inks were doped with coumarin derivatives to act as molecular luminescent sensors that allow the monitoring of the kinetics of in situ photopolymerization in 3D (DLP) printing and bioprinting using pneumatic extrusion techniques, making it possible to study the changes in the system in real time. The efficiency of the systems was tested on compositions containing monomers: poly(ethylene glycol) diacrylates and photoinitiators: 2,4,6-trimethylbenzoyldi-phenylphosphinate and lithium phenyl-2,4,6-trimethylbenzoylphosphinate. The selected formulations were spectroscopically characterized and examined for their photopolymerization kinetics and rheological properties. This is important because of the fact that spectroscopic characterization, examination of photopolymerization kinetics, and rheological properties provide valuable insights into the behaviour of photocurable resin dedicated for 3D printing processes. The next step involved printing tests on commercially available 3D printers. In turn, printing carried out as part of the work on commercially available 3D printers further verified the effectiveness of the formulations. Moreover the formulation components and the resulting 3D objects were tested for their antiproliferative effects on the selected Chinese hamster ovary cell line, CHO-K1.

Surgical Extrusion of Three Premolars to Re-establish the Biological Width: Case Series.

This case series was to describe the use of surgical extrusion for three different cases as a technique to re-establish the biological width in patients with insufficient crown height. Surgical extrusion serves as an important means to reestablishing a proper biological width. Such method provides an excellent alternative for the restoration of teeth with insufficient ferrule and ensuring a suitable dental restoration. This case series describes the management of three different cases with compromised teeth #25, #35, and #44, respectively. The approach involved the surgical extrusion of the compromised sites from subgingival to supragingival and the splinting of the teeth using a semi-rigid splint. A successful prognosis was observed on follow-up visits. This technique is a good alternative for general practitioners because of its easy implementation and time efficiency. In addition, the method requires less equipment and provides for adequate space for the re-establishment of biological width. Such technique can re-establish a healthy biological width, the existing occlusion can be maintained without alterations, and it demonstrated the suitability of surgical extrusion technique in such clinical situations. Case selection is equally important. Cases with single-rooted teeth with fractures or caries in proximity to the marginal bone level without vertical root fractures generally provide positive outcomes on providing this treatment. How to cite this article: Boreak N, Al Moaleem MM, Zain AA, et al. Surgical Extrusion of Three Premolars to Re-establish the Biological Width: Case Series. J Contemp Dent Pract 2024;25(6):593-598.

Impact of agar–glycerol ratios on the physicochemical properties of biodegradable seaweed films: A compositional study

To develop technology more applicable to industrial settings, this study aimed to produce agar-based bioplastic films using extrusion followed by hot compression. The research examined various amounts of glycerol incorporation as the plasticizer, which also facilitated the flowability of the extrusion process. These variations included agar–glycerol ratios of 75:25, 70:30, 65:35, 60:40, and 55:45 (% w/w). Moreover, the films underwent thorough testing to assess their physical, mechanical, chemical, water sensitivity, surface imaging, and biodegradability properties. The results showed that increasing the amount of glycerol in the agar film matrix generally made the films more sensitive to water, resulting in greater hydrophilicity. This change was primarily owing to the increased presence of hydroxyl groups. It also affected other characteristics, such as enhancing the film's stretchability and thermal stability. Furthermore, a decrease in film density was observed, leading to reduced tensile strength and barrier properties. Moreover, the higher glycerol content improved its surface wettability and the higher agar content accelerated the film's biodegradability rate. Microstructural examination using scanning electron microscopy and chemical analysis (FTIR) revealed a homogeneous mixture of agar and glycerol produced through the extrusion process. These findings demonstrate the potential of extrusion techniques for the large-scale production of agar-based bioplastics.