Search Results (100)

Silicon carbide (SiC) is the leading wide bandgap semiconductor for high-power and high-temperature electronics, but the high defect density still limits device performance. This study investigates how inclusions, Basal Plane Dislocations (BPDs), and Threading Screw Dislocations (TSDs) in 4H-SiC substrates affect epitaxial defect formation. Twenty 200 mm SiC wafers were analyzed after epitaxial growth in two industrial Chemical Vapor Deposition (CVD) reactors, one using Trichlorosilane/Ethylene (Reactor A) and the other Silane/Propane (Reactor B). Defects were characterized using Candela (KLA), Altair (KLA), XRTmicron LAB (Rigaku), SICA (Lasertec), and Crossbeam (ZEISS) dual-beam SEM system. Statistical correlation showed that the conversion rate of embedded particles decreases with particle depth and increases with particle size. Reactor A exhibited lower propagation rates, indicating better suppression of substrate-related defects. SEM/FIB-EDX analyses suggested that carbon inclusions generate pits while metallic inclusions induce triangular defects. Dislocation analysis confirmed a strong correlation between TSDs and BPDs with carrots and triangular defects. BPD conversion rates were estimated at about 98.3% (Reactor A) and 99.8% (Reactor B). These results emphasize the importance of substrate quality and buffer layer optimization to minimize defect propagation. Full article

The Cândești necropolis is currently the largest excavated Bronze Age necropolis in Romania, with approximately 800 graves. Notably, one grave from an earlier phase of the Monteoru culture (c. 2200–1850 BC) contained a remarkable necklace composed of 22 perforated gastropod shells and a metal pendant. Our investigation adopted an integrated approach, including taxonomic identification, taphonomic, technological and functional analyses, experimental studies, and physico-chemical investigations (Fourier Transform Infrared Spectroscopy and Raman spectroscopy) of the pigment traces present on the shells’s surface. For the metal pendant, X-Ray Fluorescence analysis was conducted to ascertain its elemental composition. The combined analysis yielded unexpected insights: the shells, belonging to the genus Conus, originated from the Mediterranean region. The perforations were not the result of anthropic intervention; rather, they were the result of natural processes, indicating that the shells were collected from thanatocoenoses. The shells were assembled into the necklace using a thread colored with a red pigment. The perforations show signs of prolonged use, suggesting that the necklace was not only a funerary offering. In conclusion, our study indicated that these exotic shells were collected post-mortem already perforated through a rubbing process in the seashore sediments, transported to the site from a distance, and prior to the death of the owner, had been previously worn as personal adornment before being deposited as grave goods. Full article

Friction stir spot welding (FSSW) is a novel variant of Friction Stir welding (FSW), developed by Mazda Motors and Kawasaki Heavy Industries to join similar and dissimilar materials in a solid state. It is an economic and environmentally friendly alternative to resistance spot welding (RSW). The FSSW technique, however, includes some structural defects imbedded within the weld joint, such as keyhole formation, hook crack, and bond line oxidation challenging the joint strength. The unique properties of nanomaterials in the reinforcement of metal matrices motivated researchers to enhance the FSSW joints’ strength. Previous studies successfully fabricated nano-reinforced FSSW joints. At different volumetric ratios of nano-reinforcement, nanoparticles may agglomerate due to inefficient stirring of the welding tool pin, forming stress concentration sites and brittle phases, affecting tensile and fatigue strength under static and cyclic loading conditions, respectively. This work investigated how the welding tool pin affects stirring efficiency by controlling the distribution of a nano-reinforcing material within the joint stir zone (SZ), and thus the tensile and fatigue strength of the FSSW joints. Sheets of AA6061-T6 of 1.8 mm thickness were used as a base material. In addition, graphene nanoplatelets (GNPs) with lateral sizes of 1–10 µm and thicknesses of 3–9 nm were used as nano-reinforcements. GNP-reinforced FSSW specimens were prepared and successfully fabricated. Optical microscope (OM) and field emission scanning electron microscope (FE-SEM) methods were employed to visualize the GNPs’ incorporation into the SZs of the FSSW joints. Micrographs of as-welded specimens showed lower formations of scattered, clustered GNPs achieved by the threaded pin tool compared to continuous agglomerations observed when the cylindrical pin tool was used. Tensile test results revealed a significant improvement of about 30% exhibited by the threaded pin tool compared to the cylindrical pin tool, while fatigue test showed an improvement of 46–24% for the low- and high-cycle fatigue, respectively. Full article

The article presents a comparative analysis of mechanical properties of M8 threaded joints produced using three different methods, in rectangular nylon (PA 12) specimens manufactured in SLS technology. Threaded holes in specimens were made by direct thread printing (specimens marked PT), thread reinforcement with Helicoil inserts (HT), and the use of heat-set inserts (IT). The specimens were subjected to a tensile testing at a constant displacement rate of 2 mm/min. The maximum force and the displacement at failure were recorded. The results indicated that the lowest load-bearing capacity F_MF was observed in the printed thread specimens, with an average value of 3.41 kN. The use of heat-set inserts increased F_MF to 3.83 kN, representing a 12% improvement. The highest load-bearing capacity was achieved in specimens reinforced with Helicoil inserts, which enhanced joint strength by 40% compared to printed thread specimens, reaching an average F_MF of 4.78 kN. In all cases, failure occurred due to the thread or insert pull-out from the specimen material. Studies have shown that the use of metal inserts significantly enhances the strength of threaded joints in SLS-printed PA12 components. Helicoil inserts provide the highest F_MF load capacity, while heat-set inserts offer better technological advantages. Although printed threads are easier to manufacture, their applicability is limited to larger thread sizes and lower mechanical loads. Full article

This article presents the results of a comprehensive material analysis of medieval decorative bands from two different excavations in present-day Poland, specifically from early medieval cemeteries in Gródek upon the Bug River and Pień. The bands are complex materials composed of various fibres and precious metals, dyed with natural dyes using recipes that are often unknown today. They represent rare archaeological finds, challenging to analyse not only due to the complexity of their structure and materials but also because of significant deterioration caused by exposure to environmental conditions and harmful substances present in the burial soil. Optical microscopy and scanning electron microscopy (SEM) facilitated the identification of raw materials, manufacturing techniques, and ornamentation. SEM coupled with energy-dispersive X-ray spectroscopy (EDS) was employed to analyse the metal threads, determine their elemental composition, and assess their preservation state. Natural dye identification was performed on selected objects using high-performance liquid chromatography combined with spectrophotometric detectors and tandem mass spectrometry with electrospray ionization (HPLC-UV-Vis-ESI-MS/MS). The analysis of these results enabled drawing conclusions regarding the origin of the bands and their manufacturing methods. The dating of the bands, based on ornamentation and manufacturing techniques, was confirmed by radiocarbon dating, indicating they date back to the 10th–12th centuries. They were produced using two weaving techniques, a narrow haberdashery loom and a tablet loom, primarily from silk and metal threads—silver and silver-gilt. Some materials consisted of red-dyed silk (using kermes or madder), including a metal thread core. The analysis also provided valuable insights into textile degradation, particularly the corrosion mechanisms affecting the metal threads. Full article

Objectives: The aim of this study is to demonstrate the efficacy of the modified technique of radical organ-preserving surgery of invasive cervical cancer (CC) in patients of reproductive age. Methods: This study included 118 patients of reproductive age (34.9 ± 4.8 years) with a morphologically verified diagnosis of invasive CC (T1a-1bNxM0). All patients underwent organ-preserving surgery in the scope of radical trachelectomy. A shape memory mesh implant woven in the form of a stocking from superelastic nickelide titanium thread with subsequent fixation with separate sutures around the perimeter was used to form the uterine closure apparatus and to strengthen the utero-vaginal anastomosis. The mesh implant was made of superelastic thin nickelide titanium threads with a diameter of 60–40 microns on a metal knitting machine. All patients were prospectively followed up for a mean of 120 months. Results: No intraoperative or postoperative complications were revealed when using a shape memory implant made of titanium nickelide during radical trachelectomy to form a locking apparatus and strengthen the anastomosis zone. No cervical stenoses or mesh failures were noted in any case. The 5-year overall and recurrence-free survival rates were 100% and 98%, respectively. Two patients indicated recurrence; it occurred in 3 and 36 months. There were 42 spontaneous pregnancies, and 29 resulted in full-term delivery, whereas 2 and 11 ended in miscarriage and early abortion, respectively. Currently, 18 patients are at different stages of the use of assisted reproductive technologies. Conclusions: The shape memory implant made of titanium nickelide integrates well into the surrounding tissues and successfully imitates the effect of the cervix. The use of this sparing-surgery technique has shown reasonably good results in carrying the pregnancy to term and good reproductive outcomes. Full article

Based on the experience gained worldwide from potential solutions to the fouling problem of fisheries and aquaculture infrastructure, we attempted to design, construct and test the antifouling efficiency of a new hybrid filament created from non-laminated copper wire braided with synthetic fibers made of Dyneema. The design involved the creation of a hybrid twine substituting a percentage of the synthetic fibers with 0.1–0.15 mm diameter copper wire at 5%, 10%, 20% and 40% levels. There is limited information in the international literature for comparison with our results, since there has never been any attempt to create such a hybrid net. The results showed that for the 6 mm mesh, the maximum openness obtained after the 8-month experimental period was 8.72%, with Cu wire substitution at 35%. For the 12 mm mesh, these values were 27.07% at 26%, and for the 20 mm mesh, they were 33.68% at 28%. A conservative average independent from mesh size to achieve optimum openness in the long term is 30 ± 4.73% Cu wire substitution. In addition, we found that both the mesh size (mm) and the copper substitution percentage affected the fouling process during the experimental period, which lasted 8 months. Full article

Objectives: Metal anchors (MA), commonly used in the early stages of rotator cuff surgical treatment development, are associated with a high risk of complications, especially in osteoporotic bone. As an alternative to rigid anchors, all-suture anchors (ASA) have been introduced for the medial row, offering promising clinical outcomes and favorable biomechanical studies. We aimed to compare the clinical outcomes of MAs and ASAs in either single-row or in medial-row suture bridge techniques in arthroscopic rotator cuff repair. Our hypothesis was that in cases where ASA was used for at least 12 months of follow-up, more favorable results would be obtained as compared to rigid anchors, and intraoperative complications such as anchor pullout would be encountered less. Methods: In this retrospective cohort analysis, we reviewed patients who underwent arthroscopic rotator cuff repair between January 2020 and December 2022. Surgeries were performed by two senior surgeons in a single tertiary center. Patients who had undergone revision surgery, had a history of previous shoulder surgeries, had massive rotator cuff tears, and partial-thickness tears; or had concomitant subscapularis tears were excluded. Preoperative and postoperative scores, including Constant–Murley (CM), Disabilities of the Arm, Shoulder, and Hand (DASH), and visual analog scale (VAS), were compared. The minimum follow-up period was 12 months. Clinical assessment of shoulder range of motion included forward flexion, abduction, internal rotation, and external rotation. Intraoperative anchor-related complications were compared. All patients underwent the same surgical technique and postoperative rehabilitation protocol. Results: A total of 142 patients (89 females, 53 males; mean age: 57.4 years) were included in the study, with 67 patients in the ASA group and 75 in the MA group. The sex distribution and mean age were similar between groups. The ASA group had 15 traumatic tears, while the MA group had 13 (p < 0.05). The mean follow-up period was 21.6 months (range 12–40 months). Preoperative CM scores were statistically better in the ASA group, but this difference was not clinically relevant (p < 0.046). The mean CM score was 75.64, the mean DASH score was 8.57, and the mean VAS was 1.38 at the postoperative period in the MA group. The mean CM score was 78.40, the mean DASH score was 9.75, and VAS was 1.59 at the postoperative period in the ASA group. Seven cases experienced anchor pullout in the MA group, and thread breakage occurred in one patient of each group (p = 0.014). The mean age of the patients with anchor pullout was significantly higher (p = 0.002). This finding was not hypothesized in the initial study design but emerged during post-hoc analysis and highlights the importance of considering bone quality in elderly patients. Conclusions: The clinical outcomes of rotator cuff repairs using all-suture anchors or metal anchors are comparable. However, ASA use may offer an advantage in elderly patients by reducing the risk of anchor pullout. Further studies assessing tendon integrity and bone quality and incorporating long-term follow-up periods are recommended to support and validate the present findings. Full article

Toxic materials are a threat in workplaces and the environment, as well as households. In them, gaseous substances are included, especially ones without any colour or fragrance, due to their non-detectability with the human senses. In this article, an attempt was made to find a solution for its detection in various conditions with the use of intelligent textiles. The approach was to perform modification on fifteen materials by screen printing using carbon nanotubes paste with expanded graphite and embroidery with stainless steel thread and then investigate their reaction with risky gases such as acetone, methanol and toluene. Four combinations of samples were tested: before tests, after the washing test and after the alkaline and acidic sweat contact test. Three materials can be highlighted. Para-aramid knitwear which reacted well to all tested gases. The biggest value of sensory percentage response was 144%. Screen-printed linen knitwear showed properly detecting skills after washing test for toluene. The biggest value of sensory percentage response was noted at 186%. The third most promising material was low surface mass cotton knitwear with embroidery which had a visible response at every stage of testing for acetone. The biggest value of sensory percentage response was 94% and the smallest one was 27%. For these three materials, repeated contact with harmful gases was tested. Simulations showed also repeated responses expressed in changes in surface resistance under changed conditions. After analysis, there is a possibility to create textile sensors for the detection of hazardous substances. Full article

We propose a new type of flexible transistor based on carbon-nanotube (CNT) composite thread (CNTCT), i.e., a thread transistor, with ionic gel. In our previous study, we demonstrated that transistor operation was possible by combining metallic and semiconducting CNTCTs as gate and channel with an insulating material. However, its performance was not sufficient. Therefore, we here aim to improve it. For this, we tried to apply ionic gel as a dielectric layer to it. With this, the transistor was expected to be an electric-double-layer transistor. The transistor performance was improved, and the on/off ratio of the transistor increased by more than 4. This is a large value compared to our previous work. In addition, we not only evaluated the performance of the transistors, but also investigated whether they could be used as logic circuits. It was confirmed that the logic circuit composed of the thread transistor also operated correctly and stably for a long period of time. It was also confirmed that the output changed in response to weak external forces. These results indicate that it is a flexible transistor that can be used in a wide range of applications such as logic circuits and sensors. Full article

The development of the field of textronics covers many directions, but the neediest are safety, medicine, and environmental protection. The solutions developed can combine the needs of many people from different social groups and ages. This leads to sustainable socio-economic, scientific and integrated approaches to sustainable development. The authors, seeing the growing need to monitor air pollution in order to increase safety, decided to develop textronic chemical sensors based on carbon-based inks and metal thread embroidery, sensitive to harmful gases and vapors based on textiles. This was to limit the production of subsequent sensors made in plastic housings containing difficult-to-recycle materials and replace them with sensors incorporated into everyday materials such as clothing, which will inform us about emerging threats not only in the place where a large plastic sensor is placed, but in every place at home, at work and outside where we will be. The authors assume that the sensors can be incorporated into clothing, e.g. work clothes, and can also be fastened from one piece of clothing to another. This increases their economic aspect and usability on a larger scale. Three materials of different composition were tested: cotton, polyester and viscose. These materials were selected based on their properties, namely the easier determination of their ability to achieve full circularity of the final product.Functional and mechanical tests of resistance to factors occurring during everyday use were carried out for the use of systems in clothing materials and to produce roller blinds and curtains. To examine the durability of the systems, electrical conductivity was checked before and after the tests. The results showed changes in resistance values after individual tests and during contact with harmful gases. Particularly noticeable are the differences between samples with embroidery and samples with inkjet paste applied. It was shown that the selected materials are suitable for the intended application, and selected modifications together with conductive materials show proper functioning in detecting harmful gases. This project demonstrates the possibility of creating chemical sensors based on printing techniques using carbon printing pastes and embroidery with a metal thread with silver on a textile substrate. Possible applications considering health and environmental aspects are presented. Full article

Board furniture’s performance and scientific design are making it popular. Research on simplifying furniture joints reduces design cycles and costs and improves structural safety. In this article, using a cantilever beam to calculate deflection theoretically simplifies the L-shaped component model and yields a joint elastic modulus formula. Finite element analysis (FEA) confirms the effectiveness of this simplified model by comparing its results with experimental data. In simplified components, the joint elastic modulus increases with length (l₂) and stabilizes at l₂/b ≥ 6 (b is the board’s thickness). The variation pattern of the joint elastic modulus equals that of the stiffness, proving its usefulness in assessing component deformation resistance. Furthermore, the component strength and stiffness are also affected by the screw spacing and connector type. In particular, the connectors type affects bamboo-oriented strand board (BOSB) component performance more than wood-oriented strand board (WOSB). Compared to WOSB, BOSB components have superior strength and stiffness and are more stable. The recommended screw spacing for L-shaped components is 48 mm. BOSB components fixed with two-in-one and metal nuts utilizing threads embedded in the board have better strength and stiffness, while for WOSB components, nylon nuts, and wooden dowel pins are more appropriate for securing. Full article

Bone cortical tissues reorganize and remodel in response to tensile forces acting on them, while compressive forces cause atrophy. However, implants support most of the payload. Bones do not regenerate, and stress shielding occurs. The aim is to analyze the biomechanical behavior of a lumbar cage to study the implant’s stress shielding. The ASTM E-9 standard was used with the necessary adjustments to perform compression tests on lumbar and thoracic porcine spinal vertebrae. Twelve cases were analyzed: six with the metal prosthesis and six with the PEEK implant. A mathematical model based on the Hertz contact theory is proposed to assess the stress shielding for endoprosthesis used in spine pathologies. The lumbar spacer (screw) helps to reduce the stress shielding effect due to the ACME thread. The best interspinous spacer is the PEEK screw. It does not embed in bone. The deformation capability increases by 11.5% and supports 78.6 kg more than a system without any interspinous spacer. Full article

Zirconia implants have emerged as a valuable alternative for clinical scenarios where aesthetic demands are high, as well as in cases of hypersensitivity to titanium or for patients who refuse metallic objects in their bodies due to personal reasons. However, these implants have undergone various changes in geometry, manufacturing techniques, and surface modifications since the introduction of the first zirconia implants. The present study aims to review the current evidence on zirconia implants, considering the changes they have undergone in recent years. Additionally, it aims to analyze the three-dimensional surface characteristics of a failed zirconia implant using scanning electron microscopy and elemental analysis with energy-dispersive X-ray spectrometry (EDX). A zirconia implant lost three weeks after placement was immediately assessed using VP-SEM equipment and chemically analyzed by EDX using a 410-M detector connected to the microscope. Sparse material depositions were found on all parts of the implant, with a notable concentration in the thread grooves. The elements identified in the sample included zirconium, oxygen, carbon, calcium, and phosphorus. This report demonstrates that the surface of zirconia implants can accumulate elements early in the process of bone matrix neoformation, which is consistent with the initial stage of osseointegration. Full article

The aim of this study is to analyze the ballistic impact behavior of a panel made of Twaron CT736 fabric with a 9 mm Full Metal Jacket (FMJ) projectile. Three shots are fired at different velocities at this panel. The ballistic impact test procedure was carried out in accordance with NIJ 010106. The NIJ-010106 standard is a document that specifies the minimum performance requirements that protection systems must meet to ensure performance. The 9 mm FMJ projectile is, according to NIJ 010106, in threat level II, but the impact velocity is in threat level IIIA. Analysis of macro-photographs of the impact of the Twaron CT736 laminated fabric panel with a 9 mm FMJ projectile involves a detailed examination of the images to gather information about the material performance and failure mechanisms at the macro- or even meso-level (fabric/layer, thread). In this paper, we analyze numerically and experimentally a panel consisting of 32 layers, made of a single material, on impact with a 9 mm FMJ projectile. The experimental results show that following impact of the panel with three projectiles, with velocities between 414 m/s and 428 m/s, partial penetration occurs, with a different number of layers destroyed, i.e., 15 layers in the case of the projectile velocity of 414 m/s, 20 layers of material in the case of the panel velocity of 422 m/s and 22 layers destroyed in the case of the projectile velocity of 428 m/s. Validation of the simulated model is achieved by two important criteria: the number of broken layers and the qualitative appearance. Four numerical models were simulated, of which three models validated the impact results of the three projectiles that impacted the panel. Partial penetration occurs in all four models, breaking the panel in the impact area, with only one exception, i.e., the number of layers destroyed, in which case the simulation did not validate the validation criterion. The performance of Twaron CT736 fabric is also given by the indentation depth values by two methods: according to NIJ 0101.06 and by 3D scanning. The NIJ 010106 standard specifies that a panel provides protection when the indentation depth values are less than 0.44 mm. Full article