Статті в журналах з теми "Fabrication additive indirecte"
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1
Li, Yan, Dichen Li, Bingheng Lu, Dajing Gao, and Jack Zhou. "Current status of additive manufacturing for tissue engineering scaffold." Rapid Prototyping Journal 21, no. 6 (October 19, 2015): 747–62. http://dx.doi.org/10.1108/rpj-03-2014-0029.
Анотація:
Purpose – The purpose of this paper is to review the current status of additive manufacturing (AM) used for tissue engineering (TE) scaffold. AM processes are identified as an effective method for fabricating geometrically complex objects directly from computer models or three-dimensional digital representations. The use of AM technologies in the field of TE has grown rapidly in the past 10 years. Design/methodology/approach – The processes, materials, precision, applications of different AM technologies and their modified versions used for TE scaffold are presented. Additionally, future directions of AM used for TE scaffold are also discussed. Findings – There are two principal routes for the fabrication of scaffolds by AM: direct and indirect routes. According to the working principle, the AM technologies used for TE scaffold can be generally classified into: laser-based; nozzle-based; and hybrid. Although a number of materials and fabrication techniques have been developed, each AM technique is a process based on the unique property of the raw materials applied. The fabrication of TE scaffolds faces a variety of challenges, such as expanding the range of materials, improving precision and adapting to complex scaffold structures. Originality/value – This review presents the latest research regarding AM used for TE scaffold. The information available in this paper helps researchers, scholars and graduate students to get a quick overview on the recent research of AM used for TE scaffold and identify new research directions for AM in TE.
2
Tony, Anthony, Ildiko Badea, Chun Yang, Yuyi Liu, Garth Wells, Kemin Wang, Ruixue Yin, Hongbo Zhang, and Wenjun Zhang. "The Additive Manufacturing Approach to Polydimethylsiloxane (PDMS) Microfluidic Devices: Review and Future Directions." Polymers 15, no. 8 (April 18, 2023): 1926. http://dx.doi.org/10.3390/polym15081926.
Анотація:
This paper presents a comprehensive review of the literature for fabricating PDMS microfluidic devices by employing additive manufacturing (AM) processes. AM processes for PDMS microfluidic devices are first classified into (i) the direct printing approach and (ii) the indirect printing approach. The scope of the review covers both approaches, though the focus is on the printed mold approach, which is a kind of the so-called replica mold approach or soft lithography approach. This approach is, in essence, casting PDMS materials with the mold which is printed. The paper also includes our on-going effort on the printed mold approach. The main contribution of this paper is the identification of knowledge gaps and elaboration of future work toward closing the knowledge gaps in fabrication of PDMS microfluidic devices. The second contribution is the development of a novel classification of AM processes from design thinking. There is also a contribution in clarifying confusion in the literature regarding the soft lithography technique; this classification has provided a consistent ontology in the sub-field of the fabrication of microfluidic devices involving AM processes.
3
Romani, Alessia, Stefan Caba, Raffaella Suriano, and Marinella Levi. "Recycling Glass and Carbon Fibers for Reusable Components in the Automotive Sector through Additive Manufacturing." Applied Sciences 13, no. 10 (May 9, 2023): 5848. http://dx.doi.org/10.3390/app13105848.
Анотація:
This work explores the use of additive manufacturing (AM) to reprocess recycled glass and carbon fibers in the automotive sector. It aims to foster exploitation of recycled Glass Fiber Reinforced Polymers (rGFRPs) and recycled Carbon Fiber Reinforced Polymers (rCFRPs) through two manufacturing workflows: indirect Fused Filament Fabrication (FFF) and UV-assisted Direct Ink Writing (UV-DIW). An industrial case study on vehicle components has been considered by prototyping one real component. After the tensile tests, some molds were fabricated with a FFF 3D printer for the indirect 3D printing process to cast an epoxy-based thermosetting resin with rGFs and rCFs. The second technology consisted in fabricating the parts by hardening in-situ a photo- and thermal-curable thermosetting acrylic liquid resin with rGFs. These results validate the use of AM and recycled composites for applications in the automotive sector. These approaches may be implemented for customizable components for batches below 100 vehicles as the first step for their exploitation.
4
Aizat, M., and S. F. Khan. "Fabrication of mandible fracture plate by indirect additive manufacturing." Journal of Physics: Conference Series 908 (October 2017): 012063. http://dx.doi.org/10.1088/1742-6596/908/1/012063.
5
Khan, S. F., Kenneth W. Dalgarno, and Rakhmad Arief Siregar. "Indirect Additive Manufacturing (AM) of Apatite-Wollastonite (A-W) Glass-Ceramic for Medical Implants." Applied Mechanics and Materials 786 (August 2015): 354–60. http://dx.doi.org/10.4028/www.scientific.net/amm.786.354.
Анотація:
Bone replacements for congenital defects, cancer resections, and traumas are typically performed using bone grafting. However, due to scarcity of the source material, synthetic materials for bone replacements are sometimes used instead. Unfortunately, the ability to engineer anatomically correct pieces of viable and functional human bone are difficult and time-consuming through conventional manufacturing methods. This paper proposes an alternative route which incorporates the use of AM technology for fabricating patient-specific implants. The implants were computer-aided design (CAD) from a stereolithography (STL) file of a mandible. AM method was combined with lost wax casting (LWC) technology to produce the customised A-W glass-ceramic implants. An initial study of sintered A-W was performed on cylindrical samples show on average 19.8% porous with on average 75% of the porosity being open and an average flexural strength of 82.6 MPa. The A-W scaffolds display a degree of macro-and micro porosity. The geometrical shape of the A-W implants shows a close resemblance to the required implant. Additive manufacturing assisted fabrication of A-W glass-ceramic provides a promising method for manufacturing customised medical implants.
6
Greeff, G. P. "Material Flow Rate Estimation in Material Extrusion Additive Manufacturing." NCSL International measure 13, no. 1 (2021): 46–56. http://dx.doi.org/10.51843/measure.13.1.5.
Анотація:
The additive manufacturing of products promises exciting possibilities. Measurement methodologies, which measure an in-process dataset of these products and interpret the results, are essential. However, before developing such a level of quality assurance several in-process measurands must be realized. One of these is the material flow rate, or rate of adding material during the additive manufacturing process. Yet, measuring this rate directly in material extrusion additive manufacturing presents challenges. This work presents two indirect methods to estimate the volumetric flow rate at the liquefier exit in material extrusion, specifically in Fused Deposition Modeling or Fused Filament Fabrication. The methods are cost effective and may be applied in future sensor integration. The first method is an optical filament feed rate and width measurement and the second is based on the liquefier pressure. Both are used to indirectly estimate the volumetric flow rate. The work also includes a description of linking the G-code command to the final print result, which may be used to create a per extrusion command model of the part.
7
Kalman, Les, and Lyndsay Desimone. "A novel workflow for indirect cobalt-chromium restorations using additive manufacturing without digital design." Journal of Dental Research, Dental Clinics, Dental Prospects 15, no. 3 (August 25, 2021): 147–51. http://dx.doi.org/10.34172/joddd.2021.025.
Анотація:
This preliminary investigation explored additive manufacturing to fabricate cobalt-chromium onlay restorations without the use of digital design. Extracted molars were prepared for four-surface onlays followed by the conventional approach for the fabrication of provisionals. The provisionals were digitized with an intraoral scanner, and stereolithography (STL) files were fabricated with additive manufacturing in cobalt-chromium, utilizing selective laser melting (SLM). Onlays were bonded to the corresponding tooth. Restorations were polished after cementation and assessed with photography, radiography, and a clinical post-cementation checklist. Cementation was unremarkable; marginal adaption and surface finish were generally acceptable. A simple, efficient, and inexpensive alternative workflow for the fabrication of indirect restorations without using the digital design is proposed.
8
He, Rujie, Niping Zhou, Keqiang Zhang, Xueqin Zhang, Lu Zhang, Wenqing Wang, and Daining Fang. "Progress and challenges towards additive manufacturing of SiC ceramic." Journal of Advanced Ceramics 10, no. 4 (July 18, 2021): 637–74. http://dx.doi.org/10.1007/s40145-021-0484-z.
Анотація:
AbstractSilicon carbide (SiC) ceramic and related materials are widely used in various military and engineering fields. The emergence of additive manufacturing (AM) technologies provides a new approach for the fabrication of SiC ceramic products. This article systematically reviews the additive manufacturing technologies of SiC ceramic developed in recent years, including Indirect Additive Manufacturing (Indirect AM) and Direct Additive Manufacturing (Direct AM) technologies. This review also summarizes the key scientific and technological challenges for the additive manufacturing of SiC ceramic, and also forecasts its possible future opportunities. This paper aims to provide a helpful guidance for the additive manufacturing of SiC ceramic and other structural ceramics.
9
Khan, Shah Fenner, M. J. German, and K. W. Dalgarno. "Indirect Additive Manufacturing Processing of Poly-Lactide-co-Glycolide." Applied Mechanics and Materials 754-755 (April 2015): 985–89. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.985.
Анотація:
The research and development of biomaterials have brought about new treatments in regenerative medicine. The research work presented in this paper focus on the use of Poly-Lactide-co-glycolide (PLGA) in the fabrication of patient specific fracture fixation plate by indirect additive manufacturing method. The use of biopolymers such as PLGA has been seen as a solution to the problems of stress shield and post-surgery inherent in biometal fixation plates. This paper discusses the consequence of this processing method on characteristics and properties of the PLGA. PLGA of ratio 50:50, 65:35 and 85:15 was processed and compared. The granules of PLGA were positioned in the cavity of the stereolithography (SLA) mould and heated under constant pressure with sintering temperature of 73°C for 2.0hours. Both the variation in samples fabricated from this process with the designed model and the changes in material characteristics are below 10%. The flexural strength for PLGA of ratio 50:50, 65:35 and 85:15 is 73.8±2.3MPa, 75.0±2.8, 60.0±11.7, respectively. The characteristics and mechanical tests indicate that the results were comparable with conventional processing of PLGA.
10
Almonti, Daniele, Gabriele Baiocco, Vincenzo Tagliaferri, and Nadia Ucciardello. "Design and Mechanical Characterization of Voronoi Structures Manufactured by Indirect Additive Manufacturing." Materials 13, no. 5 (February 29, 2020): 1085. http://dx.doi.org/10.3390/ma13051085.
Анотація:
Additive manufacturing (AM) is a production process for the fabrication of three-dimensional items characterized by complex geometries. Several technologies employ a localized melting of metal dust through the application of focused energy sources, such as lasers or electron beams, on a powder bed. Despite the high potential of AM, numerous burdens afflict this production technology; for example, the few materials available, thermal stress due to the focused thermal source, low surface finishing, anisotropic properties, and the high cost of raw materials and the manufacturing process. In this paper, the combination by AM of meltable resins with metal casting for an indirect additive manufacturing (I-AM) is proposed. The process is applied to the production of open cells metal foams, similar in shape to the products available in commerce. However, their cellular structure features were designed and optimized by graphical editor Grasshopper®. The metal foams produced by AM were cast with a lost wax process and compared with commercial metal foams by means of compression tests.
11
Asriyanti, Asriyanti, Kushendarsyah Saptaji, Nisa Khoiriyah, Muhammad Satrio Utomo, Made Subekti Dwijaya, Farid Triawan, and Muhammad Hanif Nadhif. "Fabrication of Rigid Polyurethane Foam Lumbar Spine Model for Surgical Training using Indirect Additive Manufacturing." International Journal of Technology 13, no. 8 (December 28, 2022): 1612. http://dx.doi.org/10.14716/ijtech.v13i8.6125.
12
Placzek, Gerrit, and Patrick Schwerdtner. "Concrete Additive Manufacturing in Construction: Integration Based on Component-Related Fabrication Strategies." Buildings 13, no. 7 (July 11, 2023): 1769. http://dx.doi.org/10.3390/buildings13071769.
Анотація:
Additive manufacturing (AM) with concrete, also known as concrete 3D printing, is one of the most interesting approaches for disrupting the construction industry and is currently subject to numerous research activities worldwide. AM has great potential to decrease labour costs and increase the material efficiency and geometric complexity of non-standardised building components. Although prior investigations have shown various fields of application for AM with concrete, the full potential with respect to different structural component types has not been covered yet. With this paper, an up-to-date review of fabrication strategies for the main structural components, (1) walls, (2) columns, (3) slabs, and (4) beams, is provided to identify trends and existing challenges. Therefore, firstly, AM methods and their underlying principles and characteristics for concrete components are presented, and secondly, fabrication strategies for each AM method are shown. The investigation uncovers different AM strategies (direct part vs. indirect “permanent formwork”; in situ, on-site, or off-site), which are currently being used. As a result, future applications of AM will require a hybrid manufacturing strategy combining conventional and additive manufacturing to fully explore its potential.
13
Gupta, Surojit, Daniel Trieff, Mackenzie Short, Maharshi Dey, Samuel J. A. Hocker, and Valerie Wiesner. "A Review of Additive Manufacturing Processes for Fabricating Ceramics and Composites." AM&P Technical Articles 181, no. 3 (April 1, 2023): 23–27. http://dx.doi.org/10.31399/asm.amp.2023-03.p023.
Анотація:
Abstract This article reviews additive manufacturing technologies that can be used for manufacturing ceramics and ceramic-based composites. Stereolithography and associated techniques offer the possibility of producing ceramic components with finer resolution. Powder-based techniques like binder jetting and indirect selective laser sintering can be used for designing porous ceramics. Selective laser melting offers practitioners the option of manufacturing ceramics with minimal post-processing requirements, although further research is needed to decrease its cost.
14
Woern, Aubrey, and Joshua Pearce. "3-D Printable Polymer Pelletizer Chopper for Fused Granular Fabrication-Based Additive Manufacturing." Inventions 3, no. 4 (November 27, 2018): 78. http://dx.doi.org/10.3390/inventions3040078.
Анотація:
Although distributed additive manufacturing can provide high returns on investment, the current markup on commercial filament over base polymers limits deployment. These cost barriers can be surmounted by eliminating the entire process of fusing filament by three-dimensional (3-D) printing products directly from polymer granules. Fused granular fabrication (FGF) (or fused particle fabrication (FPF)) is being held back in part by the accessibility of low-cost pelletizers and choppers. An open-source 3-D printable invention disclosed here allows for precisely controlled pelletizing of both single thermopolymers as well as composites for 3-D printing. The system is designed, built, and tested for its ability to provide high-tolerance thermopolymer pellets with a number of sizes capable of being used in an FGF printer. In addition, the chopping pelletizer is tested for its ability to chop multi-materials simultaneously for color mixing and composite fabrication as well as precise fractional measuring back to filament. The US$185 open-source 3-D printable pelletizer chopper system was successfully fabricated and has a 0.5 kg/h throughput with one motor, and 1.0 kg/h throughput with two motors using only 0.24 kWh/kg during the chopping process. Pellets were successfully printed directly via FGF as well as indirectly after being converted into high-tolerance filament in a recyclebot.
15
Sapkal, Pranav S., Abhaykumar M. Kuthe, Rajpal S. Kashyap, Amit R. Nayak, Sudhanshu A. Kuthe та Anuja P. Kawle. "Indirect fabrication of hydroxyapatite/β-tricalcium phosphate scaffold for osseous tissue formation using additive manufacturing technology". Journal of Porous Materials 23, № 6 (9 червня 2016): 1567–74. http://dx.doi.org/10.1007/s10934-016-0217-9.
16
Ranieri, Vittorio, Nicola Berloco, Francesca Garofalo, Liang He, Paolo Intini, and Karol J. Kowalski. "Effects of Reclaimed Asphalt, Wax Additive, and Compaction Temperature on Characteristics and Mechanical Properties of Porous Asphalt." Baltic Journal of Road and Bridge Engineering 17, no. 3 (September 28, 2022): 187–213. http://dx.doi.org/10.7250/bjrbe.2022-17.575.
Анотація:
This paper describes physical and mechanical properties of porous asphalt mixtures with various RAP amount (0%, 10%, 20%, 30%) containing one WMA additive (organic wax). The samples were prepared using the Marshall compactor at two different temperatures (125 °C, 145 °C) by fabricating six series of porous mixtures. Air void content, particle loss, stiffness modulus, indirect tensile strength, and indirect tensile strength ratio were measured and the effects of RAP, wax, and compaction temperatures were evaluated, considering the results of statistical analyses. Based on the performed tests, it has been concluded that high RAP contents (30%) in WMA-RAP PAs result in decreased porosity, permeability, and moisture resistance, and in increased cohesiveness, stiffness, and indirect tensile strength compared to the reference PAs. On the other hand, for low RAP contents (10%), WMA-RAP PAs show lower cohesiveness and indirect tensile strength, at the same time demonstrating an increase in porosity, permeability, moisture resistance, and stiffness. Reduced compaction temperatures (125 °C) particularly affect the cracking resistance.
17
Cheng, P. Y., and S. F. Khan. "Dimensional accuracy and surface finish of investment casting parts by indirect additive manufacturing from fused filament fabrication." IOP Conference Series: Materials Science and Engineering 429 (November 9, 2018): 012100. http://dx.doi.org/10.1088/1757-899x/429/1/012100.
18
Abdelaal, Osama, Saied Darwish, Khaled Abd Elmougoud, and Saleh Aldahash. "A new methodology for design and manufacturing of a customized silicone partial foot prosthesis using indirect additive manufacturing." International Journal of Artificial Organs 42, no. 11 (May 24, 2019): 645–57. http://dx.doi.org/10.1177/0391398819847682.
Анотація:
The production of customized prostheses for the foot and ankle still relies on slow and laborious steps of the traditional plaster molding fabrication techniques. Additive manufacturing techniques where three-dimensional objects can be constructed directly based on the object’s computer-aided-design data in a layerwise manner has opened the door to new opportunities for manufacturing of novel and personalized medical devices. The purpose of the present study was to develop a new methodology for design and manufacturing of a customized silicone partial foot prosthesis via an indirect additive manufacturing process. Furthermore, the biomechanics of gait of a subject with partial foot amputation wearing the custom silicone foot prosthesis manufactured by the indirect additive manufacturing was characterized, in comparison with a matched healthy participant. This study has confirmed the possibility of producing silicone partial foot prosthesis by indirect additive manufacturing procedure. The amputated subject reported total comfort using the custom prosthesis during walking, as well as cosmetic advantages. The prosthesis restored the foot geometry and normalized many of gait characteristics. The findings presented here contribute to introduce a proper understanding of biomechanics of walking after wearing silicone partial foot prosthesis and are useful for prosthetists and rehabilitation therapists when treating patients after partial foot amputation.
19
Moreira, Mariana F., Akel F. Kanaan, and Ana P. Piedade. "Indirect Additive Manufacturing: A Valid Approach to Modulate Sorption/Release Profile of Molecules from Chitosan Hydrogels." Polymers 14, no. 13 (June 21, 2022): 2530. http://dx.doi.org/10.3390/polym14132530.
Анотація:
This work studied the influence of hydrogel’s physical properties (geometry and hierarchical roughness) on the in vitro sorption/release profiles of molecules. To achieve this goal, chitosan (CS) solutions were cast in 3D-printed (3DP) molds presenting intricate shapes (cubic and half-spherical with/without macro surface roughness) and further immersed in alkaline solutions of NaOH and NaCl. The resulting physically crosslinked hydrogels were mechanically stable in aqueous environments and successfully presented the shapes and geometries imparted by the 3DP molds. Sorption and release profiles were evaluated using methyl orange (MO) and paracetamol (PMOL) as model molecules, respectively. Results revealed that distinct MO sorption/PMOL release profiles were obtained according to the sample’s shape and presence/absence of hierarchical roughness. MO sorption capacity of CS samples presented both dependencies of hierarchical surface and geometry parameters. Hence, cubic samples without a hierarchical surface presented the highest (up to 1.2 × greater) dye removal capacity. Moreover, PMOL release measurements were more dependent on the surface area of hydrogels, where semi-spherical samples with hierarchical roughness presented the fastest (~1.13 × faster) drug delivery profiles. This work demonstrates that indirect 3DP (via fused filament fabrication (FFF) technology) could be a simple strategy to obtain hydrogels with distinct sorption/release profiles.
20
Dimashkieh, Reda Mohiddin, Mohiddin R. Dimashkieh, and Amir M. Dimashkieh. "Simplifying Direct Pattern Technique using Fiber Post." International Journal of Prosthodontics and Restorative Dentistry 6, no. 2 (2016): 25–27. http://dx.doi.org/10.5005/jp-journals-10019-1149.
Анотація:
ABSTRACT Direct intraoral fabrication of cast post and core restorations for endodontically treated teeth can be challenging and time consuming. In addition, accurate intraoral fabrication of resin patterns with intracervicular margins is not always possible as a result of restricted access and difficult isolation. This article presents a direct-indirect method that uses different diameters of prefabricated posts as fiber post and polyvinyl siloxane material as a mold for fabrication of multiple post patterns. How to cite this article Dimashkieh RM, Dimashkieh MR, Dimashkieh AM. Simplifying Direct Pattern Technique using Fiber Post. Int J Prosthodont Restor Dent 2016;6(2):25-27.
21
Re, Dino, Gabriele Augusti, Massimo Amato, Giancarlo Riva, and Davide Augusti. "Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers." Case Reports in Dentistry 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/849273.
Анотація:
No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients’ restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with laminate nanohybrid resin composite veneers. A step-by-step protocol is proposed for diagnostic evaluation, mock-up fabrication and trial, teeth preparation and impression, and adhesive cementation. The resolution of initial esthetic issues, patient satisfaction, and nice integration of indirect restorations confirmed the success of this anterior dentition rehabilitation.
22
Carreira, Pedro, Fábio Cerejo, Nuno Alves, and Maria Teresa Vieira. "In Search of the Optimal Conditions to Process Shape Memory Alloys (NiTi) Using Fused Filament Fabrication (FFF)." Materials 13, no. 21 (October 22, 2020): 4718. http://dx.doi.org/10.3390/ma13214718.
Анотація:
This research was performed so as to investigate the additive manufacturing of NiTi shape memory alloys, which is associated with direct processes, such as selective laser melting. In addition to its expensive production costs, NiTi readily undergoes chemical and phase modifications, mainly as a result of Ni loss during processing as a result of high temperatures. This research explores the potential usefulness of NiTi as well as its limitations using indirect additive processes, such as fused filament fabrication (FFF). The first step was to evaluate the NiTi critical powder volume content (CPVC) needed to process high-quality filaments (via extrusion). A typical 3D printer can build a selected part/system/device layer-by-layer from the filaments, followed by debinding and sintering (SDS), in order to generate a near-net-shape object. The mixing, extruding (filament), printing (shaping), debinding, and sintering steps were extensively studied in order to optimize their parameters. Moreover, for the sintering step, two main targets should be met, namely: the reduction of contamination during the process in order to avoid the formation of secondary phases, and the decrease in sintering temperature, which also contributes to reducing the production costs. This study aims to demonstrate the possibility of using FFF as an additive manufacturing technology for processing NiTi.
23
Xiao, Fan, Shunyu Jin, Wan Zhang, Yingxin Zhang, Hang Zhou, and Yuan Huang. "Wearable Pressure Sensor Using Porous Natural Polymer Hydrogel Elastomers with High Sensitivity over a Wide Sensing Range." Polymers 15, no. 12 (June 19, 2023): 2736. http://dx.doi.org/10.3390/polym15122736.
Анотація:
Wearable pressure sensors capable of quantifying full-range human dynamic motionare are pivotal in wearable electronics and human activity monitoring. Since wearable pressure sensors directly or indirectly contact skin, selecting flexible soft and skin-friendly materials is important. Wearable pressure sensors with natural polymer-based hydrogels are extensively explored to enable safe contact with skin. Despite recent advances, most natural polymer-based hydrogel sensors suffer from low sensitivity at high-pressure ranges. Here, by using commercially available rosin particles as sacrificial templates, a cost-effective wide-range porous locust bean gum-based hydrogel pressure sensor is constructed. Due to the three-dimensional macroporous structure of the hydrogel, the constructed sensor exhibits high sensitivities (12.7, 5.0, and 3.2 kPa−1 under 0.1–20, 20–50, and 50–100 kPa) under a wide range of pressure. The sensor also offers a fast response time (263 ms) and good durability over 500 loading/unloading cycles. In addition, the sensor is successfully applied for monitoring human dynamic motion. This work provides a low-cost and easy fabrication strategy for fabricating high-performance natural polymer-based hydrogel piezoresistive sensors with a wide response range and high sensitivity.
24
Galati, Manuela, and Paolo Minetola. "Analysis of Density, Roughness, and Accuracy of the Atomic Diffusion Additive Manufacturing (ADAM) Process for Metal Parts." Materials 12, no. 24 (December 9, 2019): 4122. http://dx.doi.org/10.3390/ma12244122.
Анотація:
Atomic Diffusion Additive Manufacturing (ADAM) is a recent layer-wise process patented by Markforged for metals based on material extrusion. ADAM can be classified as an indirect additive manufacturing process in which a filament of metal powder encased in a plastic binder is used. After the fabrication of a green part, the plastic binder is removed by the post-treatments of washing and sintering (frittage). The aim of this work is to provide a preliminary characterisation of the ADAM process using Markforged Metal X, the unique system currently available on the market. Particularly, the density of printed 17-4 PH material is investigated, varying the layer thickness and the sample size. The dimensional accuracy of the ADAM process is evaluated using the ISO IT grades of a reference artefact. Due to the deposition strategy, the final density of the material results in being strongly dependent on the layer thickness and the size of the sample. The density of the material is low if compared to the material processed by powder bed AM processes. The superficial roughness is strongly dependent upon the layer thickness, but higher than that of other metal additive manufacturing processes because of the use of raw material in the filament form. The accuracy of the process achieves the IT13 grade that is comparable to that of traditional processes for the production of semi-finished metal parts.
25
Al-Qahtani, Amal S., Huda I. Tulbah, Mashael Binhasan, Maria S. Abbasi, Naseer Ahmed, Sara Shabib, Imran Farooq, et al. "Surface Properties of Polymer Resins Fabricated with Subtractive and Additive Manufacturing Techniques." Polymers 13, no. 23 (November 24, 2021): 4077. http://dx.doi.org/10.3390/polym13234077.
Анотація:
This study aimed to compare the surface roughness, hardness, and flexure strength of interim indirect resin restorations fabricated with CAD-CAM (CC), 3D printing (3D), and conventional techniques (CV). Twenty disk (3 mm × Ø10 mm) and ten bar specimens (25 × 2 × 2 mm) were fabricated for the CC, 3D, and CV groups, to be used for surface roughness, micro-hardness, and flexural strength testing using standardized protocol. Three indentations for Vickers micro-hardness (VHN) were performed on each disk and an average was identified for each specimen. Surface micro-roughness (Ra) was calculated in micrometers (μm) using a 3D optical non-contact surface microscope. A three-point bending test with a universal testing machine was utilized for assessing flexural strength. The load was applied at a crosshead speed of 3 mm/min over a distance of 25 mm until fracture. Means and standard deviations were compared using ANOVA and post hoc Tukey–Kramer tests, and a p-value of ≤0.05 was considered statistically significant. Ra was significantly different among the study groups (p < 0.05). Surface roughness among the CC and CV groups was statistically comparable (p > 0.05). However, 3D showed significantly higher Ra compared to CC and CV samples (p < 0.05). Micro-hardness was significantly higher in 3D samples (p < 0.05) compared to CC and CV specimens. In addition, CC and CV showed comparable micro-hardness (p > 0.05). A significant difference in flexural strength was observed among the study groups (p < 0.05). CC and 3D showed comparable strength outcomes (p > 0.05), although CV specimens showed significantly lower (p < 0.05) strength compared to CC and 3D samples. The 3D-printed provisional restorative resins showed flexural strength and micro-hardness comparable to CAD-CAM fabricated specimens, and surface micro-roughness for printed specimens was considerably higher compared to CAD-CAM and conventional fabrication techniques.
26
Huang, Xiao, Shuo Mei, Yazhi Li, Mingyang Li, Shujun Zhou, and Hongfei Shang. "Effect of TiC Content on Microstructure and Wear Performance of 17-4PH Stainless Steel Composites Manufactured by Indirect Metal 3D Printing." Materials 16, no. 19 (September 28, 2023): 6449. http://dx.doi.org/10.3390/ma16196449.
Анотація:
In order to improve the performance of 17-4PH under wear conditions (e.g., gears, etc.) and reduce the cost of metal additive manufacturing, TiC needs to be added to 17-4PH to improve its wear resistance. Micron-sized TiC-reinforced 17-4PH stainless steel composites with different contents (0–15 wt%) have been prepared by fused filament fabrication 3D printing for the first time. The effects of TiC content on the structure and properties of composites were studied by XRD, SEM, and sliding wear. The obtained results show that the microstructure of TiC-reinforced 17-4PH stainless steel composites mainly consists of austenite. With the increase in TiC content, the grain size is obviously refined, and the average grain size decreases from 65.58 μm to 19.41 μm. The relative densities of the composites are maintained above 95% with the addition of TiC. The interfaces between TiC particles and the 17-4PH matrix are metallurgical bonds. The hardness of the composites increases and then decreases with increasing TiC content, and the maximum hardness (434 HV) is obtained after adding 10 wt.% of TiC content. The wear rate of the composites was reduced from 2.191 × 10−5 mm3 /(N‧m) to 0.509 × 10−5 mm3 /(N‧m), which is a 3.3-fold increase in wear resistance. The COF value declines with the addition of TiC. The reasons for the significant improvement in the composites’ performance are fine grain strengthening, solid solution strengthening, and second phase strengthening. The wear mechanisms are mainly abrasive and adhesive wear. Compared to the 10 wt% TiC composites, the 15 wt% TiC composites show limited improvement in wear resistance due to more microcracks and TiC agglomeration.
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Park, Dae-Wook, Tam Minh Phan, and Yeong-Min Kim. "Influence of Antistripping Additives and Rejuvenators on Healing Performance of Moisture-Damaged HMA." Advances in Materials Science and Engineering 2020 (May 29, 2020): 1–12. http://dx.doi.org/10.1155/2020/9260978.
Анотація:
This study aims to evaluate the effect of different rejuvenators and antistripping agents on the healing performance of hot mix asphalt (HMA). Two damage HMA series (e.g., moisture damage and aged damage) were subjected to either induction or microwave heating. A PG64-22 virgin and aged binder were used and modified with several additives. Three long-term aged binders (e.g., PAV5, PAV15, and PAV20) were conducted by pressure aging vessel (PAV) test. The moisture damage series fabricating with a new binder was further categorized into four different freeze-thaw (FT) cycles (e.g., 0FT, 1FT, 3FT, and 5FT). Also, the aged series was fabricated with three different aged binders. A total of eight damage-healing cycles were applied to all asphalt mixtures, examined by the three-point bending test. The moisture resistance of modified asphalt mixture was examined by indirect tensile strength test. Overall, asphalt mixtures modified with either antistripping additives or rejuvenators not only obtained higher moisture resistance but also gained better healing performance under moisture damage. In addition, the study showed a probable correlation between moisture damage and long-term aging in terms of healing performance, such as PAV15 and 3FT cycles and PAV20 and 5FT cycles.
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Doyle, Stephanie E., Lauren Henry, Ellen McGennisken, Carmine Onofrillo, Claudia Di Bella, Serena Duchi, Cathal D. O'Connell, and Elena Pirogova. "Characterization of Polycaprolactone Nanohydroxyapatite Composites with Tunable Degradability Suitable for Indirect Printing." Polymers 13, no. 2 (January 18, 2021): 295. http://dx.doi.org/10.3390/polym13020295.
Анотація:
Degradable bone implants are designed to foster the complete regeneration of natural tissue after large-scale loss trauma. Polycaprolactone (PCL) and hydroxyapatite (HA) composites are promising scaffold materials with superior mechanical and osteoinductive properties compared to the single materials. However, producing three-dimensional (3D) structures with high HA content as well as tuneable degradability remains a challenge. To address this issue and create homogeneously distributed PCL-nanoHA (nHA) scaffolds with tuneable degradation rates through both PCL molecular weight and nHA concentration, we conducted a detailed characterisation and comparison of a range of PCL-nHA composites across three molecular weight PCLs (14, 45, and 80 kDa) and with nHA content up to 30% w/w. In general, the addition of nHA results in an increase of viscosity for the PCL-nHA composites but has little effect on their compressive modulus. Importantly, we observe that the addition of nHA increases the rate of degradation compared to PCL alone. We show that the 45 and 80 kDa PCL-nHA groups can be fabricated via indirect 3D printing and have homogenously distributed nHA even after fabrication. Finally, the cytocompatibility of the composite materials is evaluated for the 45 and 80 kDa groups, with the results showing no significant change in cell number compared to the control. In conclusion, our analyses unveil several features that are crucial for processing the composite material into a tissue engineered implant.
29
El Chawich, Ghenwa, Joelle El Hayek, Vincent Rouessac, Didier Cot, Bertrand Rebière, Roland Habchi, Hélène Garay, et al. "Design and Manufacturing of Si-Based Non-Oxide Cellular Ceramic Structures through Indirect 3D Printing." Materials 15, no. 2 (January 8, 2022): 471. http://dx.doi.org/10.3390/ma15020471.
Анотація:
Additive manufacturing of Polymer-Derived Ceramics (PDCs) is regarded as a disruptive fabrication process that includes several technologies such as light curing and ink writing. However, 3D printing based on material extrusion is still not fully explored. Here, an indirect 3D printing approach combining Fused Deposition Modeling (FDM) and replica process is demonstrated as a simple and low-cost approach to deliver complex near-net-shaped cellular Si-based non-oxide ceramic architectures while preserving the structure. 3D-Printed honeycomb polylactic acid (PLA) lattices were dip-coated with two preceramic polymers (polyvinylsilazane and allylhydridopolycarbosilane) and then converted by pyrolysis respectively into SiCN and SiC ceramics. All the steps of the process (printing resolution and surface finishing, cross-linking, dip-coating, drying and pyrolysis) were optimized and controlled. Despite some internal and surface defects observed by topography, 3D-printed materials exhibited a retention of the highly porous honeycomb shape after pyrolysis. Weight loss, volume shrinkage, roughness and microstructural evolution with high annealing temperatures are discussed. Our results show that the sacrificial mold-assisted 3D printing is a suitable rapid approach for producing customizable lightweight highly stable Si-based 3D non-oxide ceramics.
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Seah, H., T. P. Tan, M. L. Chong, and J. Leong. "NEWater—multi safety barrier approach for indirect potable use." Water Supply 8, no. 5 (December 1, 2008): 573–88. http://dx.doi.org/10.2166/ws.2008.130.
Анотація:
Singapore, a small island city-state depends on four sources, namely local catchment, imported water from Malaysia, desalinated water, and NEWater, to provide for its daily water consumption of about 1.36 million m3 per day. NEWater, a high grade reclaimed water, is key in achieving water sustainability through the multiplying effect of water reuse. In addition to being used for direct non-potable use (DNU) in wafer fabrication processes and other industrial processes, NEWater is being injected into surface reservoirs for indirect potable use (IPU). To ensure the safety of NEWater for IPU, PUB has adopted a multi barrier safety approach. The multi safety barrier approach starts from source and extends to taps in households in stages, namely source control; greater than 85% of wastewater from domestic source; comprehensive secondary wastewater treatment; microfiltration (MF) process, reverse osmosis (RO) process and ultra-violet (UV) disinfection in NEWater production; natural attenuation in surface reservoirs; as well as conventional water treatment process of coagulation, flocculation, sand filtration and disinfection. The approach is further enhanced by a comprehensive water quality monitoring programme that includes emerging contaminants of concern and a strict operating philosophy. The water quality test results are in turn reviewed by experts from local universities as well as overseas experts of international standing. Over the years of operations, NEWater has been found to be well within WHO Drinking Water Guidelines and USEPA Drinking Water Standards and each safety barrier has a significant role to play in ensuring the safety of NEWater for IPU.
31
Łazińska, M., T. Durejko та W. Polkowski. "The Effect of Nanometric α-Al2O3 Addition on Structure and Mechanical Properties of Feal Alloys Fabricated by Lens Technique". Archives of Metallurgy and Materials 62, № 3 (26 вересня 2017): 1703–12. http://dx.doi.org/10.1515/amm-2017-0260.
Анотація:
AbstractResults of the first principle study on a fabrication of FeAl intermetallic based alloy with an addition of nanometric αAl2O3(n-Al2O3) particles by the LENS method and a subsequent characterization of the as received materials’ structure and properties, are shown in the present work. A series of samples were manufactured using LENS technique while a control of temperature and the size of melted metal pool. The presence of ceramics nanoparticles was not directly confirmed by microscopy observations. Neither aluminum nor oxygen content was not elevated in the material with n-Al2O3content. Although, indirect methods revealed influence of n-Al2O3addition on the manufactured elements structure. Analyses of porosity has shown that addition of 2% vol. n-Al2O3significantly decreases this feature (~1%), as compared to the reference material made of pure FeAl intermetallic alloy (~5%). The addition of n-Al2O3causes an increase of grain size in Fe40Al intermetallic alloy. An oxidation resistance has been also improved what was associated to the n-Al2O3addition. Four times lower increase of samples mass was noticed for sample with the n-Al2O3addition as compared to the pure Fe40Al intermetallic alloy.
32
Golunova, Anna, Nadiia Velychkivska, Zuzana Mikšovská, Václav Chochola, Josef Jaroš, Aleš Hampl, Ognen Pop-Georgievski, and Vladimír Proks. "Direct and Indirect Biomimetic Peptide Modification of Alginate: Efficiency, Side Reactions, and Cell Response." International Journal of Molecular Sciences 22, no. 11 (May 27, 2021): 5731. http://dx.doi.org/10.3390/ijms22115731.
Анотація:
In the fast-developing field of tissue engineering there is a constant demand for new materials as scaffolds for cell seeding, which can better mimic a natural extracellular matrix as well as control cell behavior. Among other materials, polysaccharides are widely used for this purpose. One of the main candidates for scaffold fabrication is alginate. However, it lacks sites for cell adhesion. That is why one of the steps toward the development of suitable scaffolds for cells is the introduction of the biofunctionality to the alginate structure. In this work we focused on bone-sialoprotein derived peptide (TYRAY) conjugation to the molecule of alginate. Here the comparison study on four different approaches of peptide conjugation was performed including traditional and novel modification methods, based on 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxy succinimide (EDC/NHS), 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMTMM), thiol-Michael addition and Cu-catalyzed azide–alkyne cycloaddition reactions. It was shown that the combination of the alginate amidation with the use of and subsequent Cu-catalyzed azide–alkyne cycloaddition led to efficient peptide conjugation, which was proven with both NMR and XPS methods. Moreover, the cell culture experiment proved the positive effect of peptide presence on the adhesion of human embryonic stem cells.
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Mocanu, Aura-Cătălina, Florin Miculescu, Andreea Elena Constantinescu, Mădălina-Andreea Pandele, Ștefan Ioan Voicu, Anișoara Cîmpean, Marian Miculescu, and Andreea Mariana Negrescu. "Selection Route of Precursor Materials in 3D Printing Composite Filament Development for Biomedical Applications." Materials 16, no. 6 (March 15, 2023): 2359. http://dx.doi.org/10.3390/ma16062359.
Анотація:
Additive manufacturing or 3D printing technologies might advance the fabrication sector of personalised biomaterials with high-tech precision. The selection of optimal precursor materials is considered the first key-step for the development of new printable filaments destined for the fabrication of products with diverse orthopaedic/dental applications. The selection route of precursor materials proposed in this study targeted two categories of materials: prime materials, for the polymeric matrix (acrylonitrile butadiene styrene (ABS), polylactic acid (PLA)); and reinforcement materials (natural hydroxyapatite (HA) and graphene nanoplatelets (GNP) of different dimensions). HA was isolated from bovine bones (HA particles size < 40 μm, <100 μm, and >125 μm) through a reproducible synthesis technology. The structural (FTIR-ATR, Raman spectroscopy), morphological (SEM), and, most importantly, in vitro (indirect and direct contact studies) features of all precursor materials were comparatively evaluated. The polymeric materials were also prepared in the form of thin plates, for an advanced cell viability assessment (direct contact studies). The overall results confirmed once again the reproducibility of the HA synthesis method. Moreover, the biological cytotoxicity assays established the safe selection of PLA as a future polymeric matrix, with GNP of grade M as a reinforcement and HA as a bioceramic. Therefore, the obtained results pinpointed these materials as optimal for future composite filament synthesis and the 3D printing of implantable structures.
34
Ajayi, Y. O., and B. O. Akinboboye. "A pilot survey of impression materials and techniques used by dentists in the fabrication of fixed indirect restorations." Nigerian Dental Journal 20, no. 1 (January 1, 2012): 27–30. http://dx.doi.org/10.61172/ndj.v20i1.119.
Анотація:
Objective: To assess the choice of impression material and impression technique used by Nigerian dentists for the fabrication of cast restoration.
Method: A self administered questionnaire was distributed to dentists present at two national dental meeting held at Abuja and Lagos in 2011. The questionnaire assessed their choice of impression materials and technique.
Result: Fifty one out of 70 questionnaires were returned filled giving a response rate of 73%. There were 54.9% of the respondents who reported addition curing silicone impression as their first choice material for cast restorations, while 27.4% use alginate as first choice impression. The use of stock plastic trays by the respondents was significantly higher than metal and custom trays. Two-third of the respondents poured their impressions within one hour. All the respondents poured alginate impression after 15 minutes. A significantly high percentage (76%) of the respondents did not retract the free gingival before taking impression. Conclusion: The use of alginate impressions to produce cast restorations was common among the respondents. Since no previous study has documented the use of alginate to produce accurate fitting cast restorations, there is need to investigate the accuracy of alginate impressions in a clinical setting.
35
Balestra, Dario, Morgan Lowther, Cecilia Goracci, Mauro Mandurino, Silvia Cortili, Gaetano Paolone, Chris Louca, and Alessandro Vichi. "3D Printed Materials for Permanent Restorations in Indirect Restorative and Prosthetic Dentistry: A Critical Review of the Literature." Materials 17, no. 6 (March 18, 2024): 1380. http://dx.doi.org/10.3390/ma17061380.
Анотація:
The objective of this study was to review the scientific evidence currently available on 3D printable materials and 3D printing technologies used for the fabrication of permanent restorations, focusing on material properties that are clinically relevant. A literature search was performed on four databases (MEDLINE/PubMed, Scopus, Cochrane Library, Web of Science) for articles published from January 2013 until November 2023, using a combination of free words: (restorative dentistry OR prosthetic dentistry) AND (3D printing OR additive manufacturing OR rapid prototyping) AND materials. Two reviewers screened titles and/or abstracts of 2.468 unique studies. In total, 83 studies were selected for full-text reading, from which 36 were included in the review. The assessed variables were mechanical properties, reporting in most of the cases positive results, dimensional accuracy and fit, reporting conflicting results with a predominance of positive, aesthetic properties, with positive reports but scarcely addressed, and biological properties, almost unexplored in independent studies. Despite numerous studies with positive results in favor, papers with negative outcomes were also retrieved. Aesthetic and biological properties are conversely still mostly unexplored. There remains a lack of conclusive evidence for viable 3D printable restorative and prosthodontic materials for permanent restorations. Research should be strengthened by defining international standards for laboratory testing and, where pre-clinical data are promising, conducting clinical trials.
36
DITTRICH, T. R., S. W. HAAN, M. M. MARINAK, D. E. HINKEL, S. M. POLLAINE, R. McEACHERN, R. C. COOK, et al. "Capsule design for the National Ignition Facility." Laser and Particle Beams 17, no. 2 (April 1999): 217–24. http://dx.doi.org/10.1017/s0263034699172070.
Анотація:
Several choices exist in the design and production of capsules intended to ignite and propagate fusion burn of the deuterium–tritium (D–T) fuel when imploded by indirect drive at the National Ignition Facility (NIF). These choices include ablator material, ablator dopant concentration and distribution, capsule dimensions, and X-ray drive profile (shock timings and strengths). The choice of ablator material must also include fabrication and material characteristics, such as attainable surface finishes, permeability, strength, transparency to radio frequency and infrared radiation, thermal conductivity, and material homogeneity. Understanding the advantages and/or limitations of these choices is an ongoing effort for LLNL and LANL designers. At this time, simulations in one-, two-, and three-dimensions show that capsules with either a copper-doped beryllium or a polyimide (C22H10N2O4) ablator material have both the least sensitivity to initial surface roughnesses and favorable fabrication qualities. Simulations also indicate the existence of capsule designs based on these ablator materials which ignite and burn when imploded by less than nominal laser performance (900-kJ energy, 250-TW power, producing 250-eV peak radiation temperature). We will describe and compare these reduced-scale capsules, in addition to several designs which use the expected 300-eV peak X-ray drive obtained from operating the NIF laser at 1.3 MJ and 500 TW.
37
Conceição, Pedro, Jaime Portugal, and Cristina Bettencourt Neves. "Evaluation of Removable Partial Denture Metal Frameworks Produced by Digital Methods—A Systematic Review." Applied Sciences 13, no. 19 (September 29, 2023): 10824. http://dx.doi.org/10.3390/app131910824.
Анотація:
(1) Introduction: This review aimed to synthesize the significant literature addressing digital techniques for producing removable partial denture (RPD) metal frameworks, focusing on oral fit outcomes. (2) Material and Methods: A systematic review of the Web of Science and Pubmed databases was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. The selection was for original articles in English containing relevant data on RPD metal frameworks produced with digital techniques, including study characteristics, digital techniques, and fit assessment methods and outcomes. (3) Results: From the 967 search studies, 405 were duplications, and 521 were excluded after screening against set criteria. A manual search included 21 studies resulting in 62 papers for review. Extra-oral was more frequently used than intra-oral scanning. The computer-assisted design was the most applied digital technique. Additive manufacturing was preferred to milling for direct and indirect fabrication of frameworks. Fit assessments were based on qualitative measures, but quantitative evaluation showed acceptable clinical fit for RPDs made by digital protocols. (4) Conclusions: The combination of direct metal additive manufacturing with conventional impression was the most used protocol and included better qualitative and quantitative fit outcomes than the other digital protocols.
38
Fujii, Takuro, Tatsurou Hiraki, Takuma Aihara, Hidetaka Nishi, Koji Takeda, Tomonari Sato, Takaaki Kakitsuka, Tai Tsuchizawa, and Shinji Matsuo. "Development of an Epitaxial Growth Technique Using III-V on a Si Platform for Heterogeneous Integration of Membrane Photonic Devices on Si." Applied Sciences 11, no. 4 (February 18, 2021): 1801. http://dx.doi.org/10.3390/app11041801.
Анотація:
The rapid increase in total transmission capacity within and between data centers requires the construction of low-cost, high-capacity optical transmitters. Since a tremendous number of transmitters are required, photonic integrated circuits (PICs) using Si photonics technology enabling the integration of various functional devices on a single chip is a promising solution. A limitation of a Si-based PIC is the lack of an efficient light source due to the indirect bandgap of Si; therefore, hybrid integration technology of III-V semiconductor lasers on Si is desirable. The major challenges are that heterogeneous integration of III-V materials on Si induces the formation of dislocation at high process temperature; thus, the epitaxial regrowth process is difficult to apply. This paper reviews the evaluations conducted on our epitaxial growth technique using a directly bonded III-V membrane layer on a Si substrate. This technique enables epitaxial growth without the fundamental difficulties associated with lattice mismatch or anti-phase boundaries. In addition, crystal degradation correlating with the difference in thermal expansion is eliminated by keeping the total III-V layer thickness thinner than ~350 nm. As a result, various III-V photonic-device-fabrication technologies, such as buried regrowth, butt-joint regrowth, and selective area growth, can be applicable on the Si-photonics platform. We demonstrated the growth of indium-gallium-aluminum arsenide (InGaAlAs) multi-quantum wells (MQWs) and fabrication of lasers that exhibit >25 Gbit/s direct modulation with low energy cost. In addition, selective-area growth that enables the full O-band bandgap control of the MQW layer over the 150-nm range was demonstrated. We also fabricated indium-gallium-arsenide phosphide (InGaAsP) based phase modulators integrated with a distributed feedback laser. Therefore, the directly bonded III-V-on-Si substrate platform paves the way to manufacturing hybrid PICs for future data-center networks.
39
Farah Hamizah Puad@Paat, Nawrah Afnan Ashraf, and Fadzidah Mohd Idris. "Fabrication and Characterization of Nanocoils CNT/PLA Filament at Different Filler’s Percentages as Electromagnetic Wave Absorbers." Journal of Advanced Research in Micro and Nano Engieering 19, no. 1 (May 30, 2024): 86–98. http://dx.doi.org/10.37934/armne.19.1.8698.
Анотація:
The rapid development of electronic technology and communication networks has resulted in high levels of electromagnetic interference (EMI) pollution, indirectly making electromagnetic wave (EMW) absorbers of great interest among researchers. The characteristics of an ideal EMW absorber should be lightweight, thin, strong and capable of absorbing the EMW in a broad frequency range. Recently, carbon-based materials such as carbon nanotubes (CNTs) have gained good popularity for their unique properties including lightweight, high mechanical strength, good electrical and thermal conductivity and wide frequency bandwidth. However, carbon nanotubes are very conductive and tend to agglomerate due to the van der Waals forces. Therefore, the incorporation of CNTs into polymer helps to improve the EMW absorption mechanism. This research focuses on fabricating electromagnetic wave absorbers with nanocomposite based on CNT/PLA filament for additive manufacturing (3D printing). Polylactic acid (PLA) with different weight percentages of CNT fillers (1, 3, 5 wt%) was extruded to fabricate a composite filament of a diameter of 1.75 mm. The results show that different percentages of CNTs fillers have a significant effect on the morphological and crystallographic phase structure, Raman scattering and EMW absorption properties.
40
Nik Lah, Nik Muhammad Izzudin, Tuan Amran Tuan Abdullah, Muhammad Hakimi Sawal, Nur Izzati Hanani Hazril, Reem Abdullah Rashid, and Mohammad Saifulddin Mohd Azami. "Fibrous silica bismuth sulfide: An advanced material towards promising photoelectrochemical water-splitting." E3S Web of Conferences 516 (2024): 01005. http://dx.doi.org/10.1051/e3sconf/202451601005.
Анотація:
The emission of greenhouse gaseous to the atmosphere as a consequence of the utilization of fossil fuels has significantly contributed to global warming and sudden climax change which aroused a lot of concerns. This occurrence has indirectly spurred interest in hydrogen energy as a future alternative energy due to its environmentally friendly, high efficiency and long-term energy storage. Photoelectrochemical (PEC) water-splitting is a top-notch approach that can efficiently produce hydrogen. Moreover, semiconductor materials like bismuth sulfide have often been used as photoanode material in the PEC water-splitting study due to their narrow bandgap, high optical absorption coefficient, appropriate band alignment and low toxicity. Yet, Bi2S3 photoanode suffers from the rapid recombination of charge carriers which ultimately leads to sluggish water oxidation kinetics and poor charge transfer. Interestingly, the fabrication of fibrous silica bismuth sulfide (FSBS) not only demonstrated a low bandgap energy level but also effectively separated the photoproduced charges. In addition, the FSBS photoanode also showed a photocurrent density of 47.9 mA/cm2 at 1.23 VRHE which is 1.78 times greater than the commercial BS photoanode (26.9 mA/cm2). These findings indirectly exposed the potential of FSBS photoanode towards a sustainable PEC water-splitting application.
41
Pandey, Sunil, Ashmi Mewada, Mukeshchand Thakur, Sachin Shinde, Ritu Shah, Goldie Oza, and Madhuri Sharon. "Rapid Biosynthesis of Silver Nanoparticles by Exploiting the Reducing Potential of Trapa bispinosa Peel Extract." Journal of Nanoscience 2013 (August 26, 2013): 1–9. http://dx.doi.org/10.1155/2013/516357.
Анотація:
Present work reports exceptionally high reducing capacity of Trapa bispinosa to synthesize monodispersed silver nanoparticles (SNPs) within 120 seconds at 30°C which is the shortest tenure reported for SNP synthesis using plants. Moreover, we also instigated impact of different pH values on fabrication of SNPs using visible spectroscopy with respect to time. Percentage conversion of Ag+ ions into Ag° was calculated using ICP-AES analysis and was found to be 97% at pH = 7. To investigate the reduction of Ag+ ions to SNPs, cyclic voltammetry (CV) and open circuit potential (OCP) using 0.1 M KNO3 were performed. There was prompt reduction in cathodic and anodic currents after addition of the peel extract which indicates the reducing power of T. bispinosa peel. Stability of the SNPs was studied using flocculation parameter (FP) which was found to be least at all the pH values. FP was found to be indirectly proportional to stability of the nanoparticles.
42
Yao, Wendian, Dong Yang, and Dehui Li. "(Poster Award - 2nd Place) Layer-Number Engineered Momentum-Indirect Interlayer Excitons with Large Spectral Tunability." ECS Meeting Abstracts MA2023-02, no. 34 (December 22, 2023): 1642. http://dx.doi.org/10.1149/ma2023-02341642mtgabs.
Анотація:
The diversity of two-dimensional (2D) materials provides van der Waals heterostructures with abundant degrees of freedom and makes the family a promising candidate to realize novel optoelectronic devices and an attractive platform for exploring physical phenomena. Interlayer excitons in type-II van der Waals heterostructures are equipped with an oriented permanent dipole moment and long lifetime and thus would allow promising applications in excitonic and optoelectronic devices. However, in the widely studied van der Waals heterostructures constructed by transition metal dichalcogenides, the formation of interlayer excitons is limited by the lattice mismatch, rotational and translational alignment between the constituent layers, increasing the complexity of the device fabrication. Here, I will report on the robust momentum-indirect interlayer exciton emission with widely tunable emission energy via layer engineering in transition metal dichalcogenide/2D perovskite heterostructures. The transition metal dichalcogenides with different thicknesses and 2D perovskites with different layer numbers of the inorganic octahedral slabs are stacked to form type-II van der Waals heterostructures without considering special orientation arrangement and momentum mismatch. The presence of interlayer excitons is supported by the excitation-power- and temperature-dependent photoluminescence studies, photoluminescence excitation spectroscopy, time-resolved photoluminescence decay studies and electric field-dependent photoluminescence studies. Taking advantage of the thickness- or layer-number-dependence of the electronic band structure of the constituent materials, the emission energy of the interlayer excitons in our heterostructures can be tuned from 1.3 eV to 1.6 eV, providing strong evidence for the applications of van der Waals interface engineering to broad-spectrum optoelectronics. In addition, the diffusion coefficient of interlayer excitons in our heterostructures can be estimated to be ~10 cm2 s−1, which is at least one order of magnitude larger than that in the van der Waals heterostructures with Moiré superlattice, suggesting a non-localized nature that would be beneficial to the excitonic devices. Our study would offer new insights into the nature of interlayer excitons and provoke further research into their dynamics.
43
Paul, Rosaline Tina, A. R. Ligil, V. T. Vineeth, and P. P. Biswas. "Modified Precision Lingual Bonding Technique: A Step-wise Approach with Torque Angulation Device-bracket Positioning Device." APOS Trends in Orthodontics 7 (August 1, 2017): 199–203. http://dx.doi.org/10.4103/apos.apos_97_16.
Анотація:
Objectives Contemporary preadjusted edgewise appliance is all about the precision in bracket design, prescription and positioning in addition to the orthodontist’s skill and training. However, achieving it is a bigger challenge as the anatomy of the lingual surface of a tooth is uneven, dissimilar, and moreover the tooth alignment on the lingual surface is variant. Thus, the need for an accurate method of bracket positioning with predetermined torque and angulation incorporated in the brackets according to the patients’ need is of key importance. Materials and Methods A TAD- BPD machine used to enhance the accuracy of bracket positioning and bioplast accurate tray transfer technique was used. Results A step-wise procedures in bracket positioning and fabricating an indirect bonding tray for lingual orthodontics using the torque angulation device-bracket positioning device. Conclusions This technique facilitated unhindered bonding even in severely crowded cases and easy rebonding during mid-treatment stages.
44
Awang, Asmahani, Sib Krishna Ghoshal, M. R. Sahar, M. Reza Dousti, and Fakhra Nawaz. "Growth of Au Nanoparticles Stimulate Spectroscopic Properties of Er3+ Doped TeO2-ZnO-Na2O Glasses." Advanced Materials Research 895 (February 2014): 254–59. http://dx.doi.org/10.4028/www.scientific.net/amr.895.254.
Анотація:
The changes in optical properties of 70TeO2-20ZnO-10Na2O-0.5Er2O3-0.2Au glass system are stimulated by varying the heat treatment duration. The XRD data reveals broad humps in range of 25-35 degree representing the amorphous nature of the glass materials. The optical absorption edge at room temperature is used to estimate the direct (Edir), indirect (Eindir) optical band gap and the Urbach energy (EU). The value of Edirlies between 2.937 to 2.943 eV, while the value of Eindirlies within 2.478 to 2.502 eV. The value of EUis found to increase with longer time of heat treatment and lies between 0.409 to 0.424 eV. The characteristic surface plasmon resonance (SPR) band of Au nanoparticles (NPs) was observed at ~630 nm of optical absorption spectra. The strong and medium green upconversion (UC) fluorescence from Er3+centred at 547 and 533 nm were observed at room temperature, in addition to a weak red UC fluorescence from Er3+centred at 637 nm. The SPR stimulated by the presence of Au NPs enhanced the luminescence intensity by four and five folds for 1 and 4 hours heat treatment, respectively. The results indicate that there is a large influence of growth of gold NPs on the optical and spectroscopic properties of glass samples. Our results may be useful for the fabrication of nanophotonic materials.
45
Zhu, Jinyuan, Yingying Zhu, Yifan Zhou, Chen Wu, Zhen Chen, and Geng Chen. "Synergistic Promotion of Photocatalytic Degradation of Methyl Orange by Fluorine- and Silicon-Doped TiO2/AC Composite Material." Molecules 28, no. 13 (July 2, 2023): 5170. http://dx.doi.org/10.3390/molecules28135170.
Анотація:
The direct or indirect discharge of organic pollutants causes serious environmental problems and endangers human health. The high electron–hole recombination rate greatly limits the catalytic efficiency of traditional TiO2-based catalysts. Therefore, starting from low-cost activated carbon (AC), a photocatalyst (F-Si-TiO2/AC) comprising fluorine (F)- and silicon (Si)-doped TiO2 loaded on AC has been developed. F-Si-TiO2/AC has a porous structure. TiO2 nanoparticles were uniformly fixed on the surface or pores of AC, producing many catalytic sites. The band gap of F-Si-TiO2/AC is only 2.7 eV. In addition, F-Si-TiO2/AC exhibits an excellent adsorption capacity toward methyl orange (MO) (57%) in the dark after 60 min. Under the optimal preparation conditions, F-Si-TiO2/AC showed a significant photodegradation performance toward MO, reaching 97.7% after irradiation with visible light for 70 min. Even under the action of different anions and cations, its degradation efficiency is the lowest, at 64.0%, which has good prospects for practical application. At the same time, F-Si-TiO2/AC has long-term, stable, practical application potential and can be easily recovered from the solution. Therefore, this work provides new insights for the fabrication of low-cost, porous, activated, carbon-based photocatalysts, which can be used as high-performance photocatalysts for the degradation of organic pollutants.
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Afonso, João Araújo, Jorge Lino Alves, Gabriela Caldas, Barbara Perry Gouveia, Leonardo Santana, and Jorge Belinha. "Influence of 3D printing process parameters on the mechanical properties and mass of PLA parts and predictive models." Rapid Prototyping Journal 27, no. 3 (February 10, 2021): 487–95. http://dx.doi.org/10.1108/rpj-03-2020-0043.
Анотація:
Purpose This paper aims to evaluate the influence of the parameters of the Fused Filament Fabrication (FFF) process on the mechanical properties and on the mass of parts printed in Polylactic Acid (PLA). In addition, the authors developed predictive models for the analysed responses. Design/methodology/approach A full Factorial type of experimental planning method was used to define the conditions for manufacturing parts according to the variation of the construction parameters, extrusion temperature and print speed. Samples were printed for tensile, flexion and compression tests. Their mass was measured. Multiple regression methods, based on power equations, were used to build the forecasting models. Findings It was found that the extrusion temperature was the parameter of greatest influence in the variation of the analysed responses, mainly because it generates behaviour patterns and indirectly demonstrates thermal/rheological characteristics of the material used. Print speed affects responses, however, with variations dependent on part geometry and printer hardware/software. It was possible to establish prediction models with low error rates in relation to the experimental values. Originality/value The study demonstrates a good relation between the use of a structured experimental planning method as the basis for the development of predictive models based on mathematical equations, the same structure of which can be used to describe different responses.
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Favre, Luc, Mohammed Bouabdellaoui, Elie Assaf, Imene Guelil, Antoine Ronda, and Isabelle Berbezier. "(Invited) SiGe/SOI System: Mechanisms of Condensation and Strain Relaxation." ECS Meeting Abstracts MA2022-01, no. 20 (July 7, 2022): 1088. http://dx.doi.org/10.1149/ma2022-01201088mtgabs.
Анотація:
Silicon-Germanium strain engineering has been used for more than two decades in silicon based devices and has contributed to the scaling down of a transistor’s size and to significant improvements in device performance. However, while conventional silicon-germanium based electronics has experienced rapid and steady growth, thanks to this continuous miniaturization of transistors, this trend cannot continue indefinitely. Industry has already moved to alternate methods such as FinFET devices, in which a thin silicon channel is placed vertically, and the FD-SOI (FD-SGOI) design consisting of a thin film Si(SiGe) channel placed horizontally. For nodes scaled down below 28 nm, low power operation will be inherently hindered by both the imperfect interface, non-uniformity of ultra-thin films and quantum confinement effects, which increase the effective bandgap. In these devices, despite the intense research activity on the strained SiGe ultra-thin body, which accounts for a large portion of such microelectronic devices (below the 45 nm node), we still fail to properly understand the mechanisms that limit hole and electron mobilities in SGOI layers. In addition, one of the main challenges for Si based devices remains the fabrication of efficient group-IV photon sources / photon detectors compatible with the microelectronic industry, which would usefully replace the integration of III-V heterostructures on Si. The major bottleneck is that group-IV semiconductor elements have indirect bandgaps, but with possibilities of being transformed to direct bandgaps using strain engineering strategies. In this presentation, we will review the formation mechanism of Ge-rich layers on SOI by condensation at different temperatures. TEM cross-section and GPA analysis of the heterostructures will be presented. We will also report the physical and optical properties of these heterostructures. Special attention is devoted to the influence of the SiGe thickness reduction (up to few MLs), where quantum confinement is prominent in the optical properties of the layers. Raman and PL results will be presented to better explain such confinement behavior. We show that novel SGOI substrates could represent a key strategy for the fabrication of future photonic devices.
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Yanagisawa, Ryota, Shunsuke Shigaki, Kotaro Yasui, Dai Owaki, Yasuhiro Sugimoto, Akio Ishiguro, and Masahiro Shimizu. "Wearable Vibration Sensor for Measuring the Wing Flapping of Insects." Sensors 21, no. 2 (January 15, 2021): 593. http://dx.doi.org/10.3390/s21020593.
Анотація:
In this study, we fabricated a novel wearable vibration sensor for insects and measured their wing flapping. An analysis of insect wing deformation in relation to changes in the environment plays an important role in understanding the underlying mechanism enabling insects to dynamically interact with their surrounding environment. It is common to use a high-speed camera to measure the wing flapping; however, it is difficult to analyze the feedback mechanism caused by the environmental changes caused by the flapping because this method applies an indirect measurement. Therefore, we propose the fabrication of a novel film sensor that is capable of measuring the changes in the wingbeat frequency of an insect. This novel sensor is composed of flat silver particles admixed with a silicone polymer, which changes the value of the resistor when a bending deformation occurs. As a result of attaching this sensor to the wings of a moth and a dragonfly and measuring the flapping of the wings, we were able to measure the frequency of the flapping with high accuracy. In addition, as a result of simultaneously measuring the relationship between the behavior of a moth during its search for an odor source and its wing flapping, it became clear that the frequency of the flapping changed depending on the frequency of the odor reception. From this result, a wearable film sensor for an insect that can measure the displacement of the body during a particular behavior was fabricated.
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Algorri, José Francisco, Pablo Roldán-Varona, María Gabriela Fernández-Manteca, José Miguel López-Higuera, Luis Rodriguez-Cobo, and Adolfo Cobo-García. "Photonic Microfluidic Technologies for Phytoplankton Research." Biosensors 12, no. 11 (November 16, 2022): 1024. http://dx.doi.org/10.3390/bios12111024.
Анотація:
Phytoplankton is a crucial component for the correct functioning of different ecosystems, climate regulation and carbon reduction. Being at least a quarter of the biomass of the world’s vegetation, they produce approximately 50% of atmospheric O2 and remove nearly a third of the anthropogenic carbon released into the atmosphere through photosynthesis. In addition, they support directly or indirectly all the animals of the ocean and freshwater ecosystems, being the base of the food web. The importance of their measurement and identification has increased in the last years, becoming an essential consideration for marine management. The gold standard process used to identify and quantify phytoplankton is manual sample collection and microscopy-based identification, which is a tedious and time-consuming task and requires highly trained professionals. Microfluidic Lab-on-a-Chip technology represents a potential technical solution for environmental monitoring, for example, in situ quantifying toxic phytoplankton. Its main advantages are miniaturisation, portability, reduced reagent/sample consumption and cost reduction. In particular, photonic microfluidic chips that rely on optical sensing have emerged as powerful tools that can be used to identify and analyse phytoplankton with high specificity, sensitivity and throughput. In this review, we focus on recent advances in photonic microfluidic technologies for phytoplankton research. Different optical properties of phytoplankton, fabrication and sensing technologies will be reviewed. To conclude, current challenges and possible future directions will be discussed.
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Schuhladen, Katharina, Barbara Lukasiewicz, Pooja Basnett, Ipsita Roy, and Aldo R. Boccaccini. "Comparison of the Influence of 45S5 and Cu-Containing 45S5 Bioactive Glass (BG) on the Biological Properties of Novel Polyhydroxyalkanoate (PHA)/BG Composites." Materials 13, no. 11 (June 8, 2020): 2607. http://dx.doi.org/10.3390/ma13112607.
Анотація:
Polyhydroxyalkanoates (PHAs), due to their biodegradable and biocompatible nature and their ability to be formed in complex structures, are excellent candidates for fabricating scaffolds used in tissue engineering. By introducing inorganic compounds, such as bioactive glasses (BGs), the bioactive properties of PHAs can be further improved. In addition to their outstanding bioactivity, BGs can be additionally doped with biological ions, which in turn extend the functionality of the BG-PHA composite. Here, different PHAs were combined with 45S5 BG, which was additionally doped with copper in order to introduce antibacterial and angiogenic properties. The resulting composite was used to produce scaffolds by the salt leaching technique. By performing indirect cell biology tests using stromal cells, a dose-depending effect of the dissolution products released from the BG-PHA scaffolds could be found. In low concentrations, no toxic effect was found. Moreover, in higher concentrations, a minor reduction of cell viability combined with a major increase in VEGF release was measured. This result indicates that the fabricated composite scaffolds are suitable candidates for applications in soft and hard tissue engineering. However, more in-depth studies are necessary to fully understand the release kinetics and the resulting long-term effects of the BG-PHA composites.