Dataset with press forming results of unidirectional thermoplastic composite laminates including in-plane deformation data for validation of forming simulations

Truncated hemisphere parts were press formed with two commercially available unidirectional thermoplastic composite materials, namely Toray TC1225 and Solvay APC. The width and layup of the laminates were varied to influence the wrinkling severity, to trigger various deformation mechanisms and to influence the amount of in-plane deformation. A total of eight layup/width combinations were selected and formed in triplicate for both materials, resulting in the analysis of 48 parts in total. The wrinkling defects are clearly observed due to an intentional gap between the forming tools at the end of forming. Further, a dot pattern with a resolution of 3 mm was applied to the laminates prior to forming using a photoresist mask, sandblasting and heat resistant spray paint. The locations of the dots before and after forming were measured using photogrammetry and are provided in the dataset as a triangular mesh including a precision metric. Matlab functions, bundled with this dataset, allow for the reproduction of the deformation calculations and averages. Lastly, a Matlab App (GUI) is provided for easy visualization of the data. This dataset can serve as a reference for validation of composite forming simulations.

Local strain quantification of a porous carbon fiber network material

While porous materials' wide range of attractive functional properties have led to their development for a variety of applications, their intrinsically stochastic microstructures prevent straightforward approaches to predicting their mechanical behavior. This is attributed to the mechanisms that govern the macroscale behavior of these materials operating on multiple microstructure-specific length scales spanning several orders of magnitude. The goal of this work was to experimentally observe these operative deformation mechanisms to better improve the development of mechanism-informed models that more accurately predict the behavior of these materials. In this study compression tests were conducted on a porous carbon fiber network material. The resulting macroscale mechanical properties and mesoscale deformation behavior were tied together through digital image correlation (DIC) strain mapping. It was shown that deformation accumulation occurred via both reversible (fiber bending and sliding) and irreversible (fiber and junction failure) ways. The presence of irreversible deformation is indicated by strain being retained after unloading, with values of up to 0.426 locally and 0.248 globally. Local and macroscopic recovery of up to 0.306 and 0.207 strain respectively showcase the operation of reversible deformation. Furthermore, the calculation of energy loss coefficients increasing from 0.016 to 0.371 illustrates that the deformation occurs via dissipative mechanisms.

Growth of ZnO nanorods/flowers on the carbon fiber surfaces using sodium alginate as medium to enhance the mechanical properties of composites

The chemical inertness of the carbon fiber (CF) surface results in suboptimal mechanical properties of the prepared composites. To address this issue, we employed a combination of tannic acid and 3-aminopropyltriethoxysilane mixture (TA-APTES) grafted sodium alginate (SA) as a medium to enhance the interfacial properties of composites through the growth of ZnO nanoparticles on CF surfaces. ZnO nanolayers with rod-like and flower-like structures were obtained by adjusting the pH of the reaction system (pH = 10 and 12, respectively). Characterization results show that in comparison with the untreated CF composites, in the flexural strength, flexural modulus, interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of the as-prepared CF/TA-APTES/SA/ZnO10 (nanorods) composites were improved by 40.8 %, 58.4 %, 44.9 % and 47.8 %, respectively. The prepared CF/TA-APTES/SA/ZnO12 (nanoflowers) composite showed an increase in flexural strength, flexural modulus, ILSS and IFSS by 39.8 %, 63.6 %, 47.3 % and 48.2 %, respectively. These positive results indicate that the ZnO nanolayers increase the interfacial phase area and fiber surface roughness, thereby enhancing mechanical interlocking and load transfer between the fibers and resin matrix. This work provides a novel interfacial modification method for preparing CF composites used in longer and more durable wind turbine blades.

Environmental impacts of carbon fiber production and decarbonization performance in wind turbine blades

The application of carbon fiber in the wind power industry is of great interest in declining CO2 emissions but the carbon fiber manufacturing process is still a long way heading cleaner production. Since little to no information clarifies the dual effects from carbon fiber production to application, this study carried out a life cycle assessment (LCA) to recognize the environmental performances of polyacrylonitrile (PAN)-based carbon fiber production and explore the decarbonization effects of carbon fiber application in wind turbine blades. Based on on-site data from a leading carbon fiber production chain in China, potential environmental impacts of carbon fiber production predominantly originated from the precursor spinning stage (accounted for 13-91%). Fossil depletion (20.24 kg oil eq.), climate change (67.79 kg CO2 eq.), terrestrial ecotoxicity (165.63 kg 1,4-DCB eq.) and photochemical ozone formation (0.14 kg NOx eq.) were the four noteworthy areas to improve the sustainable development. Different scenarios in energy and advanced technology were set to explore the potential improvement of the environmental performance of carbon fiber products. Energy structure (wind power) can improve an average of 22.58% environmental benefit compared with the background scenarios. Regarding the decarbonization effects, the energy payback time and the carbon payback time were estimated to be 0.73 and 0.37 months respectively. Therefore, carbon fiber is a trustworthy material in the strategy to achieve sustainable development from a life cycle perspective.

Electrochemical oxidation and mechanism of sulfanilamide from groundwater in a flow-through system using carbon fiber (CF) anode

Metal-based anodes have been used for a long time in the electrochemical oxidation processes to remediate groundwater. However, the high cost of this technique as well as the release of potentially toxic metals (ex, lead), are major barriers being fully implemented. As an alternative of metal-based anodes, in recent years, carbon-based anodes have been paid attention due to their eco-friendliness and cost-effectiveness. This study evaluated the oxidation performance of carbon fiber (CF) anode in a flow-through system. The CF anode degraded 45-87% of the target pollutant (sulfanilamide), depending on the current intensity applied. However, no further degradation of sulfanilamide was observed after the cathode, indicating that sulfanilamide degradation occurred mainly at the anode. This study also determined the effect of electrolytes on electrochemical oxidation using chloride (Cl-), sulfate (SO42-), bicarbonate (CO3-), and synthetic groundwater. Cl- and SO42- electrolytes were converted electrochemically into active species, thereby enhancing sulfanilamide degradation, while the bicarbonate and groundwater electrolytes inhibited oxidation performance by scavenging hydroxyl radicals. A series of scavenger tests and characterization showed that the direct oxidation and hydroxyl radicals involved the sulfanilamide degradation. Especially, the production of hydroxyl radicals is more favorable in high currents than in low currents. That is, CF anode contributed to the degradation by direct oxidation of carbon-based electrodes and generation of hydroxyl radicals. In summary, this study highlights how a CF anode is capable of effectively degrading organic pollutants via anodic oxidation.

Carbon fiber-based multichannel solid-contact potentiometric ion sensors for real-time sweat electrolyte monitoring

Solid-contact ion-selective electrodes (SC-ISEs) feature miniaturization and integration that have gained extensive attention in non-invasive wearable sweat electrolyte sensors. The state-of-the-art wearable SC-ISEs mainly use polyethylene terephthalate, gold and carbon nanotube fibers as flexible substrates but suffer from uncomfortableness, high cost and biotoxicity. Herein, we report carbon fiber-based SC-ISEs to construct a four-channel wearable potentiometric sensor for sweat electrolytes monitoring (Na+/K+/pH/Cl-). The carbon fibers were extracted from commercial cloth, of which the starting point is addressing the cost and reproducibility issues for flexible SC-ISEs. The bare carbon fiber electrodes exhibited reversible voltammetric and stable impedance performances. Further fabricated SC-ISEs based on corresponding ion-selective membranes disclosed Nernstian sensitivity and anti-interface ability toward both ions and organic species in sweat. Significantly, these carbon fiber-based SC-ISEs revealed high reproducibility of standard potentials between normal and bending states. Finally, a textile-based sensor was integrated with a solid-contact reference electrode, which realized on-body sweat electrolytes analysis. The results displayed high accuracy compared with ex-situ tests by ion chromatography. This work highlights carbon fiber-based multichannel wearable potentiometric ion sensors with low cost, biocompatibility and reproducibility.

An inexpensive paracetamol sensor based on an acid-activated carbon fiber microelectrode

Paracetamol, a contaminant of emerging concern, has been detected in different bodies of water, where it can impact ecological and human health. To quantify this paracetamol, electroanalytical methods have gained support. Thus, the present study developed a simple, inexpensive, and environmentally friendly method for paracetamol quantification using a carbon fiber microelectrode based on commercial carbon fiber. To improve the carbon fiber microelectrode's paracetamol sensitivity and selectivity, it was subjected to an activation process via electrochemical oxidation in an acid medium (H2SO4 or HNO3), using 20 consecutive cycles of cyclic voltammetry. The treated (activated) carbon fiber microelectrode was characterized using scanning electron microscopy and electrochemical techniques, including chronoamperometry and electrochemical impedance spectroscopy. The H2SO4-activated carbon fiber microelectrode exhibited enhanced figures of merit, with a linear dynamic range of paracetamol detection from 0.5 to 11 μmol L-1 and a limit of detection of 0.21 μmol L-1 under optimized conditions. The method was optimized by quantifying paracetamol in commercial pharmaceutical tablets, spiked running tap water, and river water (Pita River, Quito, Ecuador, latitude -0.364955°, longitude -78.404538°); the respective recovery values were 102.89, 103.93, and 112.40%. The results demonstrated an acceptable level of accuracy and the promising applicability of this carbon fiber microelectrode as a sensor to detect paracetamol.

Comparative analysis of thermo-physical and mechanical properties of PALF/CF/epoxy resin with and without nano TiO2 filler

The performance of an engineering material depends on its potentiality and characterization under different mechanical and thermal test environments. The present research study has revealed the performance of a new class of hybrid composites, focused specially on the general trends observed in their impact of fabrication and its properties. To investigate how the mechanical and thermal qualities of the epoxy matrix may be improved, pineapple leaf fibre and carbon fibre were particularly chosen. By embedding the selected filler into the Pineapple leaf Fiber/Carbon Fiber(PALF/CF) reinforced epoxy resin, coordination effects, impact of embedding were achieved in the form of modified mechanical and thermal properties. The present research work is focused to perform the thermal and mechanical properties of pineapple leaf fiber/carbon fiber reinforced epoxy resin(ER) composites with and without particulate nano TiO2 fillers. The comparison of hybrid fibre (carbon and pineapple leaf fibre) reinforced epoxy composites with and without particulate nano TiO2 fillers was done. The results of the mechanical tests demonstrated that, in comparison to all other composites, the inclusion of nano fillers improved the tensile, flexural, and impact strengths. Nano particle reinforced with hybrid composite has a score of 23.4, whereas clean epoxy only gets a score of 4.5. It follows from this example that the presence of nanoparticles raises the residual values.

Long-term improvement of sediment in situ restoration and REDOX characteristics by Vallisneria natans coupling with carbon fiber

China is conducting ecological restoration work in urban water bodies. Under anoxic and anaerobic conditions, pollutants transform and produce odorous and black substances, deteriorating the water quality, which is a significant problem in urban water bodies. Vallisneria natans has received widespread attention for its applications in water treatment and restoration. However, the efficiency by which V. natans reduces water pollution and allows sediment remediation requires further improvement. Therefore, in this study, we investigated the effect of V. natans coupled with carbon fiber on the restoration of water bodies and sediment compared with the control group that grew V. natans without carbon fiber. The oxidation-reduction potential (ORP) was selected as the main evaluation index for the water and sediment. Dissolved oxygen in the water and total organic carbon and total nitrogen (TN) in the sediment were also evaluated. V. natans coupled with carbon fiber significantly increased the ORP; that of surface sediment increased by 50 % and that of the water body increased by 60 % compared with the sediment without any bioremediation. Chemical oxygen demand, total phosphorous, and TN in water decreased by 61.2 %, 22.9 %, and 48.3 %, respectively. These results indicate that planting V. natans with carbon fiber can reduce pollutants in water (including humus) and sediments, effectively improving ORP in water and sediment.

A study of a bio-inspired impact resistant carbon fiber laminate with a sinusoidal helicoidal structure in the mandibles of trap-jaw ants

The majority of living organisms demonstrate remarkable attributes and have evolved effective mechanisms for synthesizing impact-resistant and damage-tolerant structures. One exemplary instance is the rapid mandible strikes exhibited by trap-jaw ants, which are a highly aggressive species of terrestrial social organisms. An impact-resistant sinusoidal helicoidal architecture is discovered in the mandibles of trap-jaw ants. The bioinspired laminate with a bi-sinusoidal helicoidal structure was manufactured using unidirectional carbon fiber prepreg by mold press forming. This study examines the impact resistance and damage tolerance of a bionic laminate through low velocity impact, computed tomography, and compression after impact tests. The results demonstrate that bionic laminates effectively limit damage propagation within the plane while enhancing energy dissipation capacity. The sinusoidal helicoidal configuration enhances cushioning capability against impact forces, retards penetration under higher loads, hinders crack propagation, and improves residual strength. Bionic laminates provide a valuable solution for damage tolerance through the resistance to through-the-thickness loads. STATEMENT OF SIGNIFICANCE: Helicoidal and sinusoidal helicoidal microstructures have been identified in the cross-section of the jaws of trap-jaw ants. The multiple waviness ratio parameters are designed for fabricating a sinusoidal helicoidal structure laminate using unidirectional carbon fiber prepreg through the mold press forming technique. This results in a damage-tolerant mechanism characterized by reduced delamination damage, which leads to a stiffer mechanical response. Meanwhile, it enhances resistance to crack propagation, leading to the formation of discontinuous delamination areas and the accumulation of sub-critical failures. Additionally, the sinusoidal helicoidal structure laminate combines the cushioning performance of bi-sinusoidal arrangements with the enhanced impact resistance of helical arrangements. This design delays penetration at higher loads, resulting in increased residual strength.

Formability of curved multilayer laminates via 3D printing using twisted continuous fiber composites

3D printers can print free-form 3D shapes; however, their mechanical properties are unsatisfactory. 3D printers can print 3D shapes freely but the resulting products exhibit unsatisfactory mechanical properties. 3D printing using CFRTP enables the formation of 3D structures with improved mechanical properties. When molding a structure with curved parts using a continuous carbon-fiber-reinforced thermoplastic (CFRTP) 3D printer, the difference in the inner and outer paths of the filament width during arc printing causes the CFRTP filament to become twisted, resulting in poor molding accuracy. In this study, we evaluated the formability of laminates via 3D printing with twisted CFRTP filaments to reduce the inner and outer path differences. And the maximum change in the filament width, which is defined as the maximum width minus the minimum width in one round of fibers, was defined as the forming accuracy. In the case of single-layer printing, the filament width decreased as the twist angle increased, and the forming accuracy (variation in the filament width) decreased. However, when stacking multiple layers, the maximum change in the filament width was the least when the twist angle was 6°. The discovery of the optimum twist angle at 1 K is the most significant aspect of this study and indicates the possibility of an optimum twist angle for various values of K.

Difference in carcinogenicities of two different vapor grown carbon fibers with different physicochemical characteristics induced by intratracheal instillation in rats

BACKGROUND

Carbon fibers are high aspect ratio structures with diameters on the submicron scale. Vapor grown carbon fibers are contained within multi-walled carbon tubes, with VGCF™-H commonly applied as a conductive additive in lithium-ion batteries. However, several multi-walled carbon fibers, including MWNT-7, have been reported to induce lung carcinogenicity in rats. This study investigated the carcinogenic potential of VGCF™-H fibers in F344 rats of both sexes with the vapor grown carbon fibers VGCF™-H and MWNT-7 over 2 years. The carbon fibers were administered to rats by intratracheal instillation at doses of 0, 0.016, 0.08, and 0.4 mg/kg (total doses of 0, 0.128, 0.64, and 3.2 mg/kg) once per week for eight weeks and the rats were observed for up to 2 years after the first instillation.

RESULTS

Histopathological examination showed the induction of malignant mesothelioma on the pleural cavity with dose-dependent increases observed at 0, 0.128, 0.64, and 3.2 mg/kg in rats of both sexes that were exposed to MWNT-7. On the other hand, only two cases of pleural malignant mesothelioma were observed in the VGCF™-H groups; both rats that received 3.2 mg/kg in male. The animals in the MWNT-7 groups either died or became moribund earlier than those in the VGCF™-H groups, which is thought related to the development of malignant mesothelioma. The survival rates were higher in the VGCF™-H group, and more carbon fibers were observed in the pleural lavage fluid (PLF) of the MWNT-7 groups. These results suggest that malignant mesothelioma is related to the transfer of carbon fibers into the pleural cavity.

CONCLUSIONS

The intratracheal instillation of MWNT-7 clearly led to carcinogenicity in both male and female rats at all doses. The equivocal evidence for carcinogenic potential that was observed in male rats exposed to VGCF™-H was not seen in the females. The differences in the carcinogenicities of the two types of carbon fibers are thought due to differences in the number of carbon fibers reaching the pleural cavity. The results indicate that the carcinogenic activity of VGCF™-H is lower than that of MWNT-7.

Combining voltage-sensitive dye, carbon fiber array, and extracellular nerve electrodes using a 3-D printed recording chamber and manipulators

BACKGROUND

The analyses of neuronal circuits require high-throughput technologies for stimulating and recording many neurons simultaneously with single-neuron precision. Voltage-sensitive dyes (VSDs) have enabled the monitoring of membrane potentials of many (10-100 s) neurons simultaneously. Carbon fiber electrode (CFE) arrays allow for stimulation and recording of many neurons simultaneously, including intracellularly.

NEW METHOD

Combining CFE with VSD leverages the advantages of both technologies, allowing for stimulation of single neurons while recording the activity of the entire network. 3-D printing technology was used to develop a chamber to simultaneously perform VSD imaging, CFE array recording, and extracellular recording from individual glass electrodes.

RESULTS

Aplysia buccal ganglia were stained with VSD and imaged while also recording using a CFE array and extracellular nerve electrodes. Coincident spiking activity was recorded by VSD, CFE, and extracellular nerve electrodes. Current injection with CFE electrodes could activate and inhibit individual neurons as detected by VSD and nerve recordings.

COMPARISON TO EXISTING METHODS

The large size of traditional manipulators limits the number of electrodes used and the number of neurons recorded during an experiment. Here we present a method to build a 3-D printed recording chamber that includes a 3-axis micromanipulator to position a CFE array and eight 2-axis manipulators to position eight extracellular electrodes.

CONCLUSIONS

3-D printing technology can be used to build a custom recording chamber and micromanipulators. Combining these technologies allows for the direct modulation of the activity of neurons while recording the activity of 100 s of neurons simultaneously.

"Three-in-One" Multi-Scale Structural Design of Carbon Fiber-Based Composites for Personal Electromagnetic Protection and Thermal Management

Wearable devices with efficient thermal management and electromagnetic interference (EMI) shielding are highly desirable for improving human comfort and safety. Herein, a multifunctional wearable carbon fibers (CF) @ polyaniline (PANI) / silver nanowires (Ag NWs) composites with a "branch-trunk" interlocked micro/nanostructure were achieved through "three-in-one" multi-scale design. The reasonable assembly of the three kinds of one-dimensional (1D) materials can fully exert their excellent properties i.e., the superior flexibility of CF, the robustness of PANI, and the splendid conductivity of AgNWs. Consequently, the constructed flexible composite demonstrates enhanced mechanical properties with a tensile stress of 1.2 MPa, which was almost 6 times that of the original material. This is mainly attributed to the fact that the PNAI (branch) was firmly attached to the CF (trunk) through polydopamine (PDA), forming a robust interlocked structure. Meanwhile, the composite possesses excellent thermal insulation and heat preservation capacity owing to the synergistically low thermal conductivity and emissivity. More importantly, the conductive path of the composite established by the three 1D materials greatly improved its EMI shielding property and Joule heating performance at low applied voltage. This work paves the way for rational utilization of the intrinsic properties of 1D materials, as well as provides a promising strategy for designing wearable electromagnetic protection and thermal energy management devices.

Tetris-Style Stacking Process to Tailor the Orientation of Carbon Fiber Scaffolds for Efficient Heat Dissipation

As the miniaturization of electronic devices and complication of electronic packaging, there are growing demands for thermal interfacial materials with enhanced thermal conductivity and the capability to direct the heat toward heat sink for highly efficient heat dissipation. Pitch-based carbon fiber (CF) with ultrahigh axial thermal conductivity and aspect ratios exhibits great potential for developing thermally conductive composites as TIMs. However, it is still hard to fabricate composites with aligned carbon fiber in a general approach to fully utilize its excellent axial thermal conductivity in specific direction. Here, three types of CF scaffolds with different oriented structure were developed via magnetic field-assisted Tetris-style stacking and carbonization process. By regulating the magnetic field direction and initial stacking density, the self-supporting CF scaffolds with horizontally aligned (HCS), diagonally aligned and vertically aligned (VCS) fibers were constructed. After embedding the polydimethylsiloxane (PDMS), the three composites exhibited unique heat transfer properties, and the HCS/PDMS and VCS/PDMS composites presented a high thermal conductivity of 42.18 and 45.01 W m-1 K-1 in fiber alignment direction, respectively, which were about 209 and 224 times higher than that of PDMS. The excellent thermal conductivity is mainly ascribed that the oriented CF scaffolds construct effective phonon transport pathway in the matrix. In addition, fishbone-shaped CF scaffold was also produced by multiple stacking and carbonization process, and the prepared composites exhibited a controlled heat transfer path, which can allow more versatility in the design of thermal management system.

Impact of Internal CFRP strips on the flexural behavior of heat-damaged reinforced concrete beams

Recent theoretical developments revealed that reinforced concrete (RC) structures are susceptible to deterioration risk upon exposure to high temperatures where the mechanical properties of their constituents are affected and therefore require upgrading their overall performance. However, the overall behavior could be improved by strengthing the RC beams using the well-known carbon fiber-reinforcement polymers (CFRP) materials where its efficiency is highly limited by detachment, and debonding problems appear as a result of the weakness in the bond between the concrete surface and the strengthening material or upon the stress concentration induced by the various anchoring systems. The CFRP sheets have been integrated as internal reinforcement in the maximum bending zone within the thermally damaged beams, a new technology used in this study. The suggested method was the first of its kind and did not need an adhesive to be applied where debonding problem is eliminated. In contrast to conventionally reinforced steel, CFRP composite materials are fully compatible with flexural steel and constrained concrete. A total of 40 RC with (150 × 200) mm² and an overall length of 1100 mm concrete beams were cast, and the studied parameters were the CFRP length, position, and exposure temperature. The internal strengthening technique has been found to ensure the full utilization of the strengthening material where the externally-strengthened beams fail preceding the CFRP strain reached, and this was confirmed using the linear weighted sum method where the internal strengthening has the highest ranking based on the mechanical characteristics comparisons. Moreover, the internal CFRP reinforcement improves RC beam performance, strength, stiffness, toughness, and serviceability more than exterior CFRP sheets. However, the enhancement percentages are twice as much for internal strengthening as the external one. It has also been found that the reinforcement's location substantially impacted the number and length of flexural cracks and its failure mode. In addition, for every 1% reduction in concrete compressive strength in heat damage, the average ultimate load was reduced by 0.8%. The CFRP profitability indexes decrease as sheet number and temperature increase; the average toughness decrease at 150 °C, 250 °C, and 500 °C is 12%, 21%, and 47%, respectively.

Carbon-fiber-reinforced polyetheretherketone orthopedic implants in musculoskeletal and spinal tumors: imaging and clinical features

Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) orthopedic implants are gaining popularity in oncologic applications as they offer many potential advantages over traditional metallic implants. From an imaging perspective, this instrumentation allows for improved evaluation of adjacent anatomic structures during radiography, computed tomography (CT), and magnetic resonance imaging (MRI). This results in improved postoperative surveillance imaging quality as well as easier visualization of anatomy for potential image-guided percutaneous interventions (e.g., pain palliation injections, or ablative procedures for local disease control). CFR-PEEK devices are also advantageous in radiation oncology treatment due to their decreased imaging artifact during treatment planning imaging and decreased dose perturbation during radiotherapy delivery. As manufacturing processes for CFR-PEEK materials continue to evolve and improve, potential orthopedic applications in the spine and appendicular skeleton increase. An understanding of the unique properties of CFR-PEEK devices and their impact on imaging is valuable to radiologists delivering care to orthopedic oncology patients in both the diagnostic and interventional settings. This multidisciplinary review aims to provide a comprehensive insight into the radiologic, surgical, and radiation oncology impact of these innovative devices.

'Thermo-mechanical behavior of alternative material combinations for full-arch implant-supported hybrid prostheses with short cantilevers'

OBJECTIVES

To compare the fracture resistance (FR) of three combinations of materials for full-arch maxillary implant-supported hybrid prostheses (HPs) with short cantilevers (≤ 10 mm).

METHODS

Maxillary HPs were fabricated and classified as follows (n = 5 each): Group-1 (CC-A, control): acrylic-resin-veneered Co-Cr frameworks; Group-2 (CF-A): acrylic-resin-veneered carbon-fiber mesostructures; and Group-3 (CF-R): composite-resin-veneered carbon-fiber frames. Specimens were thermal-cycled (5,000 cycles; 5 °C-55 °C; dwell time: 30 s). Vertical loads were applied until failure, first at the 10-mm-long cantilever (LC), and, afterwards, at the anterior region (AR), using a universal testing machine (crosshead speed: 0.05 mm/s). The fracture pattern was assessed by stereomicroscope and SEM. The one-way ANOVA, the Bonferroni, and the independent samples t tests, were run (α= 0.05).

RESULTS

At LC, CF-A, and CC-A samples exhibited the highest FR values (p< 0.001), showing no differences to each other. At AR, CC-A specimens recorded the highest FR, followed by CF-A samples (p< 0.001). CF-R HPs displayed the lowest FR at both locations (p< 0.001). The only group with differences between the tested sites was the CC-A, the AR being more resistant (p< 0.001). Most CC-A and CF-A HPs failed cohesively. CF-R prostheses mainly failed adhesively.

CONCLUSIONS

Maxillary HPs with short cantilevers (≤ 10 mm) made of Co-Cr or carbon-fiber veneered with acrylic resin demonstrated an adequate mechanical resistance (> 900 N).

CLINICAL SIGNIFICANCE

For maxillary HPs with cantilevers up to 10 mm, acrylic-veneered carbon- fiber mesostructures may be recommended, whereas coating carbon-fiber frames with composite resin seems not suitable.

In situ electrodeposition of bismuth oxide nanowires @MWNT on the carbon fiber microelectrode for the sensitively electrochemical detection of folic acid

A microminiaturized electrochemical device, BiO@CNW/CFE was fabricated based on the in situ co-electrodeposition of bismuth oxide nanowires (BiNWs) and multi-walled carbon nanotubes (MWNTs) on the surface of carbon fiber electrode (CFE). The nanostructure of BiNWs could bind MWNTs on the surface of CFE during the precipitation of bismuth at the potential of -1.1 V. The vimineous nanostructure of BiO@CNW improved the surface area and electrochemical activity of the microelectrode. With the low background noise, folic acid (FA) can be detected sensitively by BiO@CNW/CFE based on the electrochemical reduction via the method of square wave voltammetry. The linear range of FA in sodium acetate-acetic acid buffer was achieved in the range of 5.00 nM-200 nM, the detection limit was estimated to be 0.63 nM. The recoveries of FA in human serum and artificial cerebral spinal fluid were between 99% and 103%, which indicates BiO@CNW/CFE was a reliable sensor for the detection of FA in biological samples.

Lignin-based carbon fibers: Insight into structural evolution from lignin pretreatment, fiber forming, to pre-oxidation and carbonization

Lignin remains the second abundant source of renewable carbon with an aromatic structure. However, most of the lignin is burnt directly for power generation, with an effective utilization rate of <2 %, making value addition on lignin an urgent requirement. From this perspective, preparation of lignin-based carbon fibers has been widely studied as an effective way to increase value addition on lignin. However, lignin species are diverse and complex in structure, and the pathway that enables changes in lignin structure during pretreatment, fiber formation, stabilization, and carbonization is still uncertain. In this review, we condense the common structural evolution route from the previous studies, which can serve as a guide towards engineered lignin carbon fibers with high performance properties.

The Use of Carbon Fiber-Reinforced Instrumentation in Patients with Spinal Oncologic Tumors: A Systematic Review of Literature and Future Directions

INTRODUCTION

Metastatic spine tumors affect over 30% of patients who have been diagnosed with cancer. While techniques in surgical intervention have undoubtedly evolved, there are some pitfalls when spinal instrumentation is required for stabilization following tumor resection. However, the use of carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implants has become increasingly popular due to improved radiolucency and positive osteobiologic properties. Here, we present a systematic review describing the use of CFR-PEEK-coated instrumentation in the oncologic population while identifying advantages and potential shortcomings of these devices.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was conducted in March 2022 to identify articles detailing the use of CFR-PEEK implants for spinal instrumentation in patients with primary and secondary spine tumors. The search was performed using the PubMed, Scopus, and Embase databases.

RESULTS

An initial search returned a total of 85 articles among the three databases used. After the exclusion of duplicates and screening of abstracts, 21 full-text articles were examined for eligibility. Eleven articles were excluded due to not fitting our inclusion and exclusion criteria. Ten articles were subsequently eligible for full-text review.

CONCLUSIONS

CFR-PEEK possesses a similar safety and efficacy profile to titanium implants but has distinct advantages. It limits artifact, increases early detection of local tumor recurrence, increases radiotherapy dose accuracy, and is associated with low complication rates (9.96%)-making it a promising alternative for the demands unique to the treatment/outcome of spinal oncologic patients.

Comparison of five different methodologies for evaluating ankle-foot orthosis stiffness

BACKGROUND

The mechanical properties of an ankle-foot orthosis (AFO) play an important role in the gait mechanics of the end user. However, testing methodologies for evaluating these mechanical properties are not standardized. The purpose of this study was to compare five different evaluation frameworks to assess AFO stiffness.

METHOD

The same 13 carbon composite AFOs were tested with five different methods. Four previously reported custom test fixtures (the BRUCE, KST, SMApp, and EMPIRE) rotated an AFO into dorsiflexion about a defined axis in the sagittal plane. The fifth method involved quasi-static deflection of AFOs into dorsiflexion by hanging weights (HW) from the footplate. AFO rotational stiffness was calculated as the linear fit of the AFO resistive torque and angular deflection. Differences between methods were assessed using descriptive statistics and a repeated measures Friedman with post-hoc Bonferroni-Holm adjusted Wilcoxon signed-rank tests.

RESULTS

There were significant differences in measured AFO stiffnesses between test methods. Specifically, the BRUCE and HW methods measured lower stiffness than both the EMPIRE and the KST. Stiffnesses measured by the SMApp were not significantly different than any test method. Stiffnesses were lowest in the HW method, where motion was not constrained to a single plane. The median difference in absolute AFO stiffness across methods was 1.03 Nm/deg with a range of [0.40 to 2.35] Nm/deg. The median relative percent difference, measured as the range of measured stiffness from the five methods over the average measured stiffness was 62% [range 13% to 156%]. When the HW method was excluded, the four previously reported test fixtures produced a median difference in absolute AFO stiffness of 0.52 [range 0.38 to 2.17] Nm/deg with a relative percent difference between the methods of 27% [range 13% to 89%].

CONCLUSIONS

This study demonstrates the importance of developing mechanical testing standards, similar to those that exist for lower limb prosthetics. Lacking standardization, differences in methodology can result in large differences in measured stiffness, particularly for different constraints on motion. Non-uniform measurement practices may limit the clinical utility of AFO stiffness as a metric in AFO prescription and future research.

Synthesis, Characterization, and Antibacterial Properties of ZnO Nanostructures Functionalized Flexible Carbon Fibers

BACKGROUND

Studies on the surface functionalization of flexible carbon fibers without any substrate by using cost-effective, fast, and practical processes that may provide antibacterial properties to carbon fiber have received great importance recently.

OBJECTIVE

The objective of this patent study is to obtain zinc oxide nanostructures functionalized carbon fibers by a facile, cheap, fast, and repeatable method, and to show their effective antibacterial activity.

METHODS

Electroplating and electrochemical anodization were used to synthesize zinc oxide nanostructures on carbon fiber surfaces, respectively, and their antibacterial properties were studied by zone inhibition test against Staphylococcus aureus and Pseudomonas aeruginosa.

RESULTS

The zinc oxide nanostructures on carbon fiber surfaces were successfully synthesized in minutes, and they exhibited effective antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa. The morphological properties of the nanocomposite were studied using scanning electron microscopy, which showed that ZnO on the CF surface exhibits a flake-like nanostructure. Fourier transform infrared spectrophotometer, x-ray diffraction spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy were used to analyze the composite's compositional, structural, crystallographic, and spectral characteristics. The results from all analyses were in a good agreement, indicating that the wurtzite crystalline ZnO nanostructure was successfully produced on the CF surface.

CONCLUSION

As a consequence, a method for the surface functionalization of carbon fiber using zinc oxide nanostructures has been developed that is feasible, low-cost, rapid, and repeatable. The flexible nanocomposite structure has a significant potential to be employed as a scaffold in sensor technology, wearable devices, and particularly in medical textiles due to its antibacterial and woven-able properties.

A closed-loop recycling process for carbon fiber-reinforced polymer waste using thermally activated oxide semiconductors: Carbon fiber recycling, characterization and life cycle assessment

The objective of this study is to investigate the properties of recycled carbon fiber (rCF) and its environmental impact, with a specific focus on the energy consumption of the recycling process based on the use of thermally activated oxide semiconductors (TASC). The mechanical and surface properties of rCF obtained under the optimal process parameters were characterized. The life cycle assessment method was used to evaluate the environmental impact of a closed-loop recycling process for carbon fiber-reinforced polymer (CFRP) waste using TASC. The results indicated that the decomposition rate of resin was 95.5 %, and no carbonaceous solid was generated. The gaseous produced of the recycling process were mainly CO₂ and H₂O, and no liquid products were produced. The surface oxidation degree of rCF was relatively slight. COOH was generated on the surface of rCF, which was conducive to improving the interfacial adhesion viscosity with resin. The monofilament tensile strength of rCF was maintained above 97 %. Compared with landfill and incineration, CFRP waste recycling using TASC can make global warming potential, acidification potential and eutrophication potential reduced by 28 %, 32 %, and 25 %, respectively. Ozone layer depletion potential, human toxicity potential and terrestrial ecotoxicity potential in disposing CFRP waste using TASC were 30 %, 21 % and 41 % of that using pyrolysis, respectively. The energy consumption in carbon fiber recycling by TASC was only 23 % of that in virgin carbon fiber manufacturing. TASC is found to be a promising potential strategy for managing CFRP waste.

Experimental investigation on a combination of soil electrokinetic consolidation and remediation of drained water using composite nanofiber-based electrodes

A novel electrokinetic geosynthetic (EKG) can be efficient in achieving multiple objectives. In this study, a new EKG as an electrode and a drainage channel in the electro-osmotic consolidation was fabricated by electrospun nanofibers containing graphene nanoparticles (GNs) attached to a carbon fiber substrate. To investigate the effectiveness of the fabricated electrodes in electro-osmotic consolidation and remediation of water drained from the system, an experimental apparatus was constructed while considering loading capability in expanded ranges and applying the electric field, and was filled with copper (Cu)-contaminated kaolinite. Experiments were divided into control (CT) and EKG groups, and three categories, C-EK, ES₁-EK, and ES₂-EK (using carbon fiber, electrospun nanofibers containing 1 wt% GNs, and electrospun nanofibers consisting of 2 wt% GNs, respectively). All the experiments were conducted with the same conditions, loading, drainage condition, and duration. However, EKG experiments were performed by employing the electric field under the vertical pressure in the range of 7-113 kPa, while the CT was conducted without the electric field. According to experimental results, 18 wt% polymethyl methacrylate in the dimethylformamide solvent containing 1 and 2 wt% GNs was selected for making a nanofibrous layer on the carbon fiber. The average diameters of the fibers were 404 ± 36 and 690 ± 62 nm and yielded at 1 and 2 wt% GNs, respectively. The results revealed that using the EKG accelerated kaolinite consolidation. The average degree of consolidation was 68 and 85% in the CT and EKG experiments, respectively. Furthermore, the fabricated electrodes were highly effective as a drainage channel for remediating water drained from the system. Moreover, the highest Cu removal efficiency was obtained in ES₂-EK (97%) and ES₁-EK (92%), respectively. Conversely, the lowest Cu removal efficiency was observed in the C-EK group (85%).

Application of Murphy - Good Plot Parameters Extraction Method on Electron Emission from Carbon Fibers

The significance of the Fowler-Nordheim-type plots lies in the possibility of extracting useful and reliable physical parameters of the field electron emitters. This is achieved by the parameter's extraction methods. We report on the application of two parameters extraction methods on field emission data from bundles of carbon fibers (CFs) grouped in nickel tubes and operated inside a typical field emission microscope setup. These methods are the Murphy-Good plot and the conventional Fowler-Nordheim plot iterative method. The physical parameters include the area extraction parameter, the notional (actual) emission area, the formal area efficiency factor and the voltage conversion length. The results obtained from the two methods are discussed and compared to shed light on the controversial nature of these methods. The mechanism of field electron emission is analyzed based on the parameters extracted.

Removal of salicylic acid by electrochemical processes using stainless steel and platinum anodes

Salicylic acid is an important pharmaceutic and widely used in plant hormones and personal care products. Peroxicoagulation (PC) method has recently been employed in treatment of various pollutants. In general, carbon-based cathode materials such as graphite and carbon fiber are used for in situ H₂O₂ production and stainless steel (SS316-L) anode for low iron production in PC studies as an efficient system modification. This study was conducted to investigate salicylic acid removal efficiency of electrochemical processes. Stainless steel was used as anode in this study. It was believed that the oxidation effect of stainless steel could be responsible for partial removal of salicylic acid. In this study, stainless steel anode and graphite or carbon fiber cathodes were employed in PC treatments for removing salicylic acid from aqueous solution, and some model trials were also made to investigate the in-situ Fe²⁺ and H₂O₂ production performance. Present findings revealed a total organic carbon (TOC) removal of 30.5% and salicylic acid removal of 69.5% at optimized conditions. The EF system modification used in the study can be proposed as an easy, low-cost and effective treatment alternative for treatment of pharmaceutical industry wastes such as salicylic acid.

Factory site analysis of respirable fibers generated during the process of cutting and grinding of carbon fibers-reinforced plastics

OBJECTIVES

Carbon fibers are used in a variety of industrial applications, based on their lightweight and high stiffness properties. There is little information on the characteristics and exposure levels of debris generated during the factory processing of carbon fibers or their composites. This study revisits the general assumption that carbon fibers or their debris released during composite processing are considered safe for human health.

METHODS

The present interventional study was conducted at a factory located in Japan, and involved on-site collection of debris generated during the industrial processing of polyacrylonitrile (PAN)-based carbon-fiber-reinforced plastic (CFRP). The debris were collected before being exhausted locally from around different factory machines and examined morphologically and quantitatively by scanning electron microscopy. The levels of exposure to respirable carbon fibers at different areas of the factory were also quantified.

RESULTS

The collected debris mainly contained the original carbon fibers broken transversely at the fiber's major axis. However, carbon fiber fragments morphologically compatible with the WHO definition of respirable fibers (length: > 5 μm, width: < 3 μm, length/width ratio: > 3:1) were also found. The concentrations of respirable fibers at the six examined factory areas under standard working conditions in the same factory were below the standard limit of 10 fibers/L, specified for asbestos dust-generating facilities under the Air Pollution Control Law in Japan.

CONCLUSIONS

Our study identified potentially dangerous respirable fibers with high aspect ratio, which was generated during the processing of PAN-based CFRP. Regular risk assessment of carbon fiber debris is necessary to ensure work environment safety.

Transcrystalline growth of PLLA on carbon fiber grafted with nano-SiO2 towards boosting interfacial bonding in bone scaffold

BACKGROUND

The reinforcement effect of fiber-reinforced polymer composites is usually limited because of the poor interfacial interaction between fiber and polymer, though fiber reinforcement is regarded as an effective method to enhance the mechanical properties of polymer.

METHODS

In this study, nano-SiO2 particles grafted by 3-Glycidoxypropyltrimethoxysilane (KH560) were introduced onto the surface of 3-Aminopropyltriethoxysilane (KH550) modified carbon fiber (CF) by a self-assembly strategy to improve the interfacial bonding between CF and biopolymer poly (lactic acid) (PLLA).

RESULTS

The results indicated that PLLA chains preferred to anchor at the surface of nano-SiO2 particles and then formed high order crystalline structures. Subsequently, PLLA spherulites could epitaxially grow on the surface of functionalized CF, forming a transcrystalline structure at the CF/PLLA interface. Meanwhile, the nano-SiO2 particles were fixed in the transcrystalline structure, which induced a stronger mechanical locking effect between CF and PLLA matrix. The results of tensile experiments indicated that the PLLA/CF-SiO2 scaffold with a ratio of CF to SiO2 of 9:3 possessed the optimal strength and modulus of 10.11 MPa and 1.18 GPa, respectively. In addition, in vitro tests including cell adhesion and fluorescence indicated that the scaffold had no toxicity and could provide a suitable microenvironment for the growth and proliferation of cell.

CONCLUSION

In short, the PLLA/CF-SiO2 scaffold with good mechanical properties and cytocompatibility had great potential in the application of bone tissue engineering.

Fabrication of NH2-MIL-125(Ti) nanodots on carbon fiber/MoS2-based weavable photocatalysts for boosting the adsorption and photocatalytic performance

Metal-organic frameworks (MOFs) are prospective photocatalysts for removing pollutants. However, the large size of MOFs results in unsatisfactory photocatalytic performance, thus restricting their further usage. Herein, ultrasmall Ti MOF (NH₂-MIL-125(Ti)) nanodots (diameter: < 10 nm) were prepared on carbon fiber (CF) (diameter: ∼7 μm) based MoS₂ (thickness: ∼20 nm, length: ∼200 nm) via a facile method and used as an efficient and reusable photocatalyst. The weaved CF/MoS₂/NH₂-MIL-125(Ti) cloth (0.15 g, 4 × 4 cm²) shows good reusability with an easy reusing process. Compared with large size NH₂-MIL-125(Ti) based sample, our well-prepared NH₂-MIL-125(Ti) nanodots based sample shows the improved surface area (290.1 m² g^-1) and it can generate more reactive oxygen species (ROS), which enhance removal performance (81.1% levofloxacin (LVFX), 67.9% acid orange 7 (AO7), 94.3% methylene blue (MB) and 100% Cr(Ⅵ)) in 120 min. Additionally, the recycling test for 4 cycles indicates high stability. This work highlights the function of easy-recyclable NH₂-MIL-125(Ti) nanodots-based heterojunctions in wastewater purification.

Fracture resistance of cantilevered full-arch implant-supported hybrid prostheses with carbon fiber frameworks after thermal cycling

OBJECTIVES

This in vitro study aimed to find the best combination of mesostructure and veneering materials for full-arch implant-supported hybrid prostheses (HPs) in terms of the fracture resistance (FR) of their cantilevers.

METHODS

Three groups (n = 5 each) of maxillary HPs were fabricated: Group-1 (CC-A, control): Co-Cr frameworks coated with acrylic resin; Group-2 (CF-A): carbon fiber veneered with acrylic resin; and Group-3 (CF-R): carbon fiber coated with composite resin. All specimens were submitted to 5,000 thermal cycles (5 °C - 55 °C, dwell time: 30 s), and subjected to a single cantilever bending test in a universal testing machine (crosshead speed: 0.5 mm/min) until failure. The fracture pattern was assessed using stereo microscope and SEM. The one-way ANOVA and Bonferroni tests were run (α= 0.05).

RESULTS

The FR yielded significant differences among the three groups (p< 0.001). CC-A samples reached the highest FR values (p ≤ 0.001), whereas both CF-A and CF-R HPs exhibited the comparably (p = 0.107) lowest FR. CC-A specimens failed cohesively (100%): mostly without chipping (80%). CF-A mesostructures were always broken at the connections of the distal implants. CF-R prostheses often failed adhesively (80%).

CONCLUSIONS

The HPs made of Co-Cr veneered with acrylic demonstrated the best mechanical behavior, being the only group whose 13-mm long cantilevers exceeded the clinically acceptable FR of 900 N. The HPs constructed with carbon fiber frameworks showed, additionally, more unfavorable fracture patterns.

CLINICAL SIGNIFICANCE

For HPs with cantilevers up to 13 mm, Co-Cr mesostructures coated with acrylic may represent the optimum combination of materials.

Multiplexing neurochemical detection with carbon fiber multielectrode arrays using fast-scan cyclic voltammetry

Carbon fiber microelectrodes (CFMEs) have been extensively used to measure neurotransmitters with fast-scan cyclic voltammetry (FSCV) due to their ability to adsorb cationic monoamine neurotransmitters. Although FSCV, in tandem with CFMEs, provides high temporal and spatial resolution, only single-channel potentiostats and electrodes have been primarily utilized. More recently, the need and use of carbon fiber multielectrode arrays has risen to target multiple brain regions. Previous studies have shown the ability to detect dopamine using multielectrode arrays; however, they are not readily available to the scientific community. In this work, we interfaced a carbon fiber multielectrode array (MEA or multielectrode array), to a commercially available four-channel potentiostat for multiplexing neurochemical measurements. The MEA's relative performance was compared to single CFMEs where dopamine detection was found to be adsorption controlled to the electrode's surface. Multiple waveforms were applied to each fiber of the multielectrode array simultaneously to detect different analytes on each electrode of the array. A proof of concept ex vivo experiment showed that the multielectrode array could record redox activity in different areas within the mouse caudate putamen and detect dopamine in a 3-mm2 area. To our knowledge, this is the first use of the multielectrode array paired with a commercially available multichannel potentiostat for multi-waveform application and neurotransmitter co-detection. This novel array may aid in future studies to better understand complex brain heterogeneity, the dynamic neurochemical environment, and how disease states or drugs affect separate brain areas concurrently. Graphical abstract.

Towards producing high-quality lignin-based carbon fibers: A review of crucial factors affecting lignin properties and conversion techniques

The production of low-cost and high-quality carbon fibers (CFs) from biorenewable lignin precursors has been of worldwide interest for decades. Although numerous works have been reported and the proposed "1.72 GPa/172 GPa" target set by the Department of Energy (DOE) has been closely met in a few studies, most lignin-based CFs (LCFs) have poor strength properties compared to industrial PAN (polyacrylonitrile)-based CFs. The production of LCFs involves several steps, and the final quality of LCFs is governed by both lignin's properties and the manufacturing processes. Therefore, understanding the key factors of producing high quality LCF is of high importance. In this review, we firstly outlined several lignin's properties (e.g., impurities, thermal properties, molecular structure) that may play important role in determining its processability and suitability as carbon fiber precursor. Secondly, conversion strategies include spinning, stabilization and carbonization, and corresponding parameters influencing the final quality of LCF are comprehensively analyzed. Last, additional characterization methods are proposed as a means to facilitate analyzing of lignin and LCF. This review attempts to provide insights towards high-quality LCF production from both material and manufacturing aspects.

High precision zero-friction magnetic dendrometer

Increasing agricultural demand for freshwater in the face of a changing climate requires improved irrigation management to maximize resource efficiency. Soil water deficits can significantly reduce plant growth and development, directly impacting crop quantity and quality. Dendrometers are a plant-based tool that have shown potential to improve irrigation management in high-value woody perennial crops (e.g., trees and vines). A dendrometer continuously measures small fluctuations in stem diameter; this has been directly correlated to water stress measurements using traditional methods. While plant-based measures of water deficits are considered to be the best measures of water stress, current dendrometer methods are imprecise due to mechanical hysteresis and thermal expansion. The high-precision dendrometer created at the OPEnS Lab alleviates these key failure points using zero-thermal expansion carbon fiber, zero friction via a spring tensioning approach, and a linear magnetic encoder. In-lab tests and field deployments have validated device measurements and the execution of these pivotal qualities. Mass deployment of these automated dendrometers has the potential to provide a continuous record of water stress, providing valuable decision support for irrigation management.

Enhanced recovery of phosphate as a value-added product from wastewater by using lanthanum modified carbon-fiber

The aim of this study is to present the potential of activated carbon fiber (CF) impregnated with lanthanum (La) as a novel adsorbent (La-CF) of phosphate-phosphorus (P) and to assess the value-added due to P-recovery from wastewater using La-CF. The CF were loaded with La and the loaded CF was then calcined at 500 °C. The La-CF adsorbent was used in a series of batch experiments to characterize the adsorption of P at pH of 6-10 and P concentrations of 1-200 mg/L. Physical-chemical properties such as surface morphology, surface charge, surface area, and surface chemistry were determined for the La-CF. The La-CF exhibited adsorption capacity of 196.5 mg/g, fast sorption kinetics and high selectivity for P removal from aqueous solution. La-CF removed 97.3% of P from wastewater and achieved P-level to below 2 mg/L. It was repetitively reused over 10 times in successive cycles to remove P from wastewater. The value-added by recovery of P from wastewater was calculated at around 0.12 US$/L, demonstrating economic benefits of La-CF. In conclusion, the successful removal, recycling, and recovery value-added of P using La-CF adsorbent displayed good potential for developing the technology for treatment of wastewaters to recover valuable compounds such as phosphorus.

Utility of carbon fiber instrumentation in spinal oncology

Spinal oncology has had many advancements often necessitating serial imaging for post-surgical treatment planning and close follow up. Traditional spinal instrumentation introduces artifact into MRI and CT imaging, which can reduce the efficacy of follow up imaging and treatment. Newly created carbon-fiber instrumentation can offer many advantages compared to traditional instrumentation while typically maintaining biomechanical stability. The utility of this new instrumentation continues to evolve as more surgeons utilize these materials, which can improve patient outcomes. We illustrate the utility of this new hardware technology through various patient examples.

Evolution of materials for implants in metastatic spine disease till date - Have we found an ideal material?

"Metastatic Spine Disease" (MSD) often requires surgical intervention and instrumentation with spinal implants. Ti6Al4V is widely used in metastatic spine tumor surgery (MSTS) and is the current implant material of choice due to improved biocompatibility, mechanical properties, and compatibility with imaging modalities compared to stainless steel. However, it is still not the ideal implant material due to the following issues. Ti6Al4V implants cause stress-shielding as their Young's modulus (110 gigapascal [GPa]) is higher than cortical bone (17-21 GPa). Ti6Al4V also generates artifacts on CT and MRI, which interfere with the process of postoperative radiotherapy (RT), including treatment planning and delivery. Similarly, charged particle therapy is hindered in the presence of Ti6Al4V. In addition, artifacts on CT and MRI may result in delayed recognition of tumor recurrence and postoperative complications. In comparison, polyether-ether-ketone (PEEK) is a promising alternative. PEEK has a low Young's modulus (3.6 GPa), which results in optimal load-sharing and produces minimal artifacts on imaging with less hinderance on postoperative RT. However, PEEK is bioinert and unable to provide sufficient stability in the immediate postoperative period. This issue may possibly be mitigated by combining PEEK with other materials to form composites or through surface modification, although further research is required in these areas. With the increasing incidence of MSD, it is an opportune time for the development of spinal implants that possess all the ideal material properties for use in MSTS. Our review will explore whether there is a current ideal implant material, available alternatives and whether these require further investigation.

Electrochemical treatment in KOH renews and activates carbon fiber microelectrode surfaces

Carbon fiber microelectrodes (CFMEs) are the standard electrodes for fast-scan cyclic voltammetry (FSCV) detection of neurotransmitters. CFMEs are generally used untreated but the surface can be activated with different treatments to improve electrochemical performance. In this work, we explored electrochemical treatments to clean and activate the CFME surface. We used different solution conditions for electrochemical treatment and found that electrochemical pretreatment in KOH outperforms treatment in KCl, H₂O₂, or HCl by accelerating the surface renewal process. The etching rate of carbon with electrochemical treatment in KOH is 37 nm/min, which is 10 times faster than that in the other solutions. Electrochemical treatment in KOH for several minutes regenerates a new carbon surface, which introduces more oxygen functional groups beneficial for adsorption and electron transfer. The KOH-treated CFMEs improved the limit of detection (LOD) to 9 ± 2 nM from 14 ± 4 nM for untreated CFMEs, and they successfully detected stimulated dopamine release in rat brain slices, demonstrating that they are stable and sensitive enough to use in biological systems. Electrochemical treatment in KOH completely restores the electrode sensitivity after biofouling. The proposed electrochemical treatment is simple and fast and can be applied prior to using CFMEs or after use to restore the surface. Thus, the method has potential to be a standard step to clean the carbon surface, or restore the sensitivity of electrodes from biofouling.

Late recognition of an early catastrophic failure of a carbon fiber reinforced distal femoral plate: A case report

The use of carbon fiber reinforced implants to address distal femur fractures has gained in popularity due to their favorable mechanical characteristics and potential for improved healing. The failure of metal locked plates for this application has been widely reported. Here is presented a novel case of early failure of a carbon fiber reinforced polyetheretherketone (PEEK) plate applied for a distal femur fracture. This is the first known report of failure of a carbon fiber reinforced distal femur plate in a patient with a traumatic fracture. Due to the radiolucent characteristics of the plate, the failure was not immediately recognized. While there may be advantages to these plates, early catastrophic failure can still occur.

Microbial nitrogen removal in synthetic aquaculture wastewater by fixed-bed baffled reactors packed with different biofilm carrier materials

Fixed-bed baffled reactors packed with carbon fiber (CFBR), polyurethane, or non-woven fabrics were developed to support microbial nitrification-denitrification reactions for nitrogen removal from synthetic aquaculture wastewater. The CFBR showed the best performance, with a short hydraulic retention time and low C/N ratio. Microbial communities in the reactor's biofilms and deposited sludge were analyzed using high-throughput sequencing and quantitative polymerase chain reactions. The biofilms efficiently enriched the nitrifying and denitrifying bacteria in the CFBR. Moreover, bacteria capable of denitrification under aerobic conditions were detected in the aerobic chamber biofilm, showing positive correlations with the main nitrifiers and denitrifiers, which provides potential synergistic interactions for simultaneous nitrification-denitrification in the aerobic chamber. A network analysis revealed that the CFBR had more complex cooperative interactions than others. This study provides insights into the influence of different carrier materials on biofilm formation, proving that the CFBR has potential applications in aquaculture wastewater treatment.

Tribological, cytotoxicity and antibacterial properties of graphene oxide/carbon fibers/polyetheretherketone composite coatings on Ti-6Al-4V alloy as orthopedic/dental implants

In this work, graphene oxide/carbon fibers/polyetheretherketone (GO/CF/PEEK) composite coatings on Ti-6Al-4V (TC4) alloy were fabricated by electrostatic powder spraying method. The coatings with 0.02 wt% GO and 25 wt% CF were made to improve the wear resistance, cytocompatibility and antibacterial properties of the TC4 as orthopedic/dental implants. The physicochemical properties involving coating thickness, Vickers hardness, micromorphology, phase structures and contact angles were investigated. The results indicated that the GO/CF/PEEK coatings can significantly decrease the coefficient of friction (COF) (from 0.433 ± 0.017 to 0.085 ± 0.008) and enhance the wear resistance of TC4 alloy during the wet friction process in sliding contact with a Si₃N₄ ball. The results showed that few scratches appeared on the GO/CF/PEEK coating. As the in vitro cytotoxicity test by murine fibroblast L929 cells shown, the GO/CF/PEEK coating revealed good cytocompatibility. More importantly, GO/CF/PEEK coating exhibited excellent suppression toward Staphylococcus aureus (S. aureus) owing to the antibacterial nature of GO. Therefore, the GO/CF/PEEK composite coated TC4 could be considered as a prospective orthopedic/dental implant material for bone tissue engineering.

Production of hydrogen-rich gases in the recycling process of residual carbon fiber reinforced polymers by pyrolysis

In this work, a novel method to valorize the polymeric matrix of residual carbon fiber reinforced polymers (CFRP) in the recycling process of carbon fibers by pyrolysis is presented. The experiments have been carried out with an expired epoxy-based pre-preg and in a lab-scale installation composed of two reactors. In the first one, pyrolysis and oxidation have been carried out, while in the second one, the gases and vapors resulting from the thermal decomposition of the polymeric resin have been thermally treated. The following operating parameters have been studied in the pyrolysis step: dwell time, the use of N₂ (N₂ flow, no N₂ flow and not even to inert the reaction medium) and the solid bed material of the second reactor. In the oxidation step, temperature and time have been optimized by using the theory of experiments based on 2 ^k factorial design was used. It has been demonstrated that clean carbon fibers and a gaseous fraction with 75% by volume of H₂ can be obtained. This is possible through a combined process of (1) CFRP thermal decomposition at 500 °C, (2) thermal treatment of gases and vapors at 900 °C in a solid bed tubular reactor filled with a waste refractory material and (3) oxidation of pyrolysis solid at 500 °C during 165 min in presence of 1.3 L air min^-1.

Management of Spinal Dumbbell Tumors via a Minimally Invasive Posterolateral Approach and Carbon Fiber-Reinforced Polyether Ether Ketone Instrumentation: Technical Note and Surgical Case Series

OBJECTIVE

Stand-alone minimally invasive approaches for the surgical management of spinal dumbbell tumors carry the risk of incomplete resections and impaired hemostasis. More-extensive approaches require subsequent instrumentation with metal artifacts impairing follow-up imaging. Here, we present a technical note on percutaneous instrumentation using carbon fiber-reinforced polyether ether ketone (CFR-PEEK) hardware combined with a minimally invasive posterolateral approach for tumor resection.

METHODS

We present a Technical Note and according case series of 7 patients with dumbbell tumors in the lumbar and thoracolumbar spine operated on between 2017 and 2020. CFR-PEEK pedicle screws and rods were inserted percutaneously. Afterwards, a dedicated self-standing retractor for posterolateral approaches was connected to the screws. Following a unilateral facetectomy, the tumor was resected in a microsurgical fashion. Clinical data are reported with respect to the Preferred Reporting Of CasE Series in Surgery (PROCESS) guidelines.

RESULTS

Four patients presented with de novo tumors. Three patients were treated for residual tumor mass after previous surgeries. Gross total resection was achieved in all 7 cases, as demonstrated by early postoperative magnetic resonance imaging. Histopathology demonstrated 5 World Health Organization grade I schwannomas, 1 grade II hemangiopericytoma, and 1 cavernous hemangioma. No postoperative complications were observed. CFR-PEEK hardware allowed unambiguous visualization of the resection cavity on follow-up imaging.

CONCLUSIONS

Resection of dumbbell tumors via a minimally invasive posterolateral approach and instrumentation with CFR-PEEK hardware allows maximal and safe resection. Due to lack of major metal artifacts, carbon fiber hardware improves the interpretation of follow-up imaging as well as planning of radiation if required for tumor recurrence.

Solitary late spinal metastasis from apocrine salivary duct carcinoma: Case report

Background

The salivary duct carcinomas (SDCs) are rare, high-grade neoplasms involving major salivary glands. Parotid is the most frequently involved gland (85%). Apocrine phenotype (histological presence of decapitation secretions) and androgen reception expression define SDC. The clinical course of these tumors is characterized by aggressive local behavior with extraglandular extension, high recurrence rates, early metastases, and poor prognoses. Despite aggressive surgical/radiation therapy management, the rates of locoregional and metastatic relapses are high, and the mortality rates over 48 months approach 65%. Notably, there is no treatment algorithm available for managing vertebral metastases from apocrine SDC.

Case Description

An elderly male presented with MR/CT findings of an isolated T11 vertebral metastasis attributed to a previously treated parotid SDC. On both CT/MR, it was an osteolytic lesion and demonstrated spinal canal infiltration. The patient underwent surgical biopsy/decompression/resection, following which the lesion histopathologically proved to be a SDC. The patient was subsequently treated with 30 Gy in 10 fractions within 2 weeks of discharge. One-month later, the MRI confirmed adequate epidural decompression without recurrence, and 9 months post-operatively, patient remained disease free.

Conclusion

Isolated metastasis attributed to parotid SDC followed by radiation therapy may result in tumor control.

Can Polyether Ether Ketone Dethrone Titanium as the Choice Implant Material for Metastatic Spine Tumor Surgery?

Instrumentation during metastatic spine tumor surgery (MSTS) provides stability to the spinal column in patients with pathologic fracture or iatrogenic instability produced while undergoing extensive decompression. Titanium is the current implant material of choice in MSTS. However, it hinders radiotherapy planning and generates artifacts, with magnetic resonance imaging and computed tomography scans used for postoperative evaluation of tumor recurrence and/or complications. The high modulus of elasticity of titanium (110 GPa) results in stress shielding, which may lead to construct failure at the bone-implant interface. Polyether ether ketone (PEEK), a thermoplastic polymer, is an emerging alternative to titanium for use in MSTS. The modulus of elasticity of PEEK (3.6 GPa) is close to that of cortical bone (17-21 GPa), resulting in minimal stress shielding. Its radiolucent and nonmetallic properties cause minimal interference with magnetic resonance imaging and computed tomography scans. PEEK also causes low-dose perturbation for radiotherapy planning. However, PEEK has reduced bioactivity with bone and lacks sufficient rigidity to be used as rods in MSTS. The reduced bioactivity of PEEK may be addressed by 1) surface modification (introducing porosity or bioactive coating with hydroxyapatite [HA] or titanium) and 2) forming composites with HA/titanium. The mechanical properties of PEEK may be improved by forming composites with HA or carbon fiber. Despite these modifications, all PEEK and PEEK-based implants are difficult to handle and contour intraoperatively. Our review provides a comprehensive overview of PEEK and modified PEEK implants, with a description of their properties and limitations, potentially serving as a basis for their future development and use in MSTS.

3D NiO nanoflakes/carbon fiber meshwork: Facile preparation and utilization as general platform for photocathodic bioanalysis

Herein, we describe a customized approach for facile preparation of three-dimensional (3D) NiO nanoflakes (NFs)/carbon fiber meshwork (CFM) and its validation as a common photocathode matrix for photoelectrochemical (PEC) bioanalysis, which to our knowledge has not been reported. Specifically, 3D NiO NFs/CFM was fabricated by a sequential liquid phase deposition and annealing process, which was then characterized by scanning electron microscopy, X-ray photoelectron spectrum, UV-vis absorption spectra and N₂ adsorption-desorption measurement. Sensitized by BiOI and incorporated with an alkaline phosphatase (ALP)/tyrosinase (TYR) bi-enzyme cascade system, a sensitive split-type cathodic PEC bioanalysis for the determination of ALP was achieved. This method can detect ALP concentrations down to 3 × 10^-5 U L^-1 with a linear response range of 0.001-10 U L^-1. Moreover, this proposed system exhibited good selectivity, stability and excellent performance for real sample analysis. This research features the facile preparation of 3D NiO NFs/CFM that could acts as a universal matrix for photocathodic analysis, and is envisioned to stimulate more effort for advanced 3D photocathode for PEC bioanalysis and beyond.

Epoxy based sandwich composite using three-dimensional integrally woven fabric as core strengthened with additional carbon face-sheets

Sandwich composites are three-dimensional (3D) composite structures that offer higher stiffness with overall low density. However, they suffer from low strength; thus, not suited for load bearing applications. In this work, an attempt is made to develop a high strength lightweight sandwich composite suited for load-bearing applications. A sandwich composite based on 3D integrally woven fabric with thickness 3 mm as the core and strengthened with additional 2x2 twill woven carbon fabric face-sheets is reported. The samples were manufactured by wet hand lay co-lamination process using Araldite® LY 1564 epoxy as the matrix polymer and with fiber fraction of 50% by weight. The number of additional carbon face-sheets over the core was varied from two to eight in steps of two. The composite samples were experimented under three-point bending and edgewise compression tests to determine the flexural and compressive strengths in both warp and weft directions. The weft direction samples yielded higher flexural and compressive strengths due to the continuous arrangement of the core pile yarn. The samples with six carbon face-sheets tested along the weft direction offered the highest specific strengths of ~409 kN m/kg and 259 kN m/kg in bending and compression tests. Similarly, the flexural strength was ~340 MPa, and compressive strength was ~217 MPa. A detailed fractography study revealed no core crushing or compression failure of the core during bending tests.

Fast chemical recycling of carbon fiber reinforced plastic at ambient pressure using an aqueous solvent accelerated by a surfactant

The properties of infusibility and insolubility in organic solvent of cured epoxy resin makes it difficult to recycle carbon fiber reinforced plastics (CFRP). We have reported the recycling of CFRPs using the oxidizing power of hydroxyl radicals generated from NaOCl solution. In our study, we used benzyltrimethylammonium bromide (BTAB) and sodium dodecyl sulfate (SDS) for the interfacial separation between the epoxy resin and carbon fibers (CF). The surfactant system maximized recycling efficiency in both pretreatment and the main reaction of the CFRP recycling process. In the second step, the reaction time to successfully reclaim the CFs was much shorter, only one hour, compared with the two-hour reaction time for the non-SDS process previously reported by us. Scanning electron microscope images and Raman analyses showed that the surface of the reclaimed CF (r-CFs) was clean and smooth without any defects, and there was no significant structural change compared to virgin CF (v-CFs). The tensile strength of r-CF was 3.42 GPa which is 96.9% of the v-CF. Thus, the CFRP recycling process using SDS not only results in r-CF with good mechanical and physical properties, but also increases recycling efficiency by reducing the time.

High-efficiency and wide-bandwidth microwave absorbers based on MoS2-coated carbon fiber

Carbon fiber (CF) is a significant multifunction material, which is extensively used in aircraft because of its superb performance. However, its microwave absorption properties (MAPs) are seriously restricted as a result of the impedance mismatch issue. To address this issue, an efficient strategy is conducted by a series of CF@MoS₂ and CF@MoS₂@Fe₃O₄ composites that are fabricated by in-situ grown MoS₂ nanosheets (MoS₂-NS) and Fe₃O₄ nanoparticles (Fe₃O₄-NPs) on the surface of CF. The results of microwave absorption performance (MAP) reveal that the minimum reflection loss (RL) can reach -21.4 dB with a CF@MoS₂ composite coating thickness of 3.8 mm; the effective attenuation bandwidth (RL < -10 dB, i.e., 90% microwave energy is attenuated) is up to 10.85 GHz (7.15-18.0 GHz). From a detailed analysis, it is observed impedance mismatch is the critical limiting factor for MAPs rather than attenuation. Furthermore, for CF@MoS₂@Fe₃O₄, the MAP is strongly dependent on the level of coating of magnetic Fe₃O₄-NPs on the surface of CF@MoS₂ composites. The mechanisms underlying the superb MAP and related phenomena are investigated, opening new directions for fabricating CF-based microwave absorbers with high efficiency and wide-bandwidth. Finally, the occurrence of multi-reflection phenomena of EM waves in absorbers are critically analyzed.

Strong and thermostable hydrothermal carbon coated 3D needled carbon fiber reinforced silicon-boron carbonitride composites with broadband and tunable high-performance microwave absorption

Excellent electromagnetic wave (EMW) absorbing materials with high-temperature stable and superior mechanical properties are among the most promising candidates for practical application. Here, novel hydrothermal carbon coated three-dimensional (3D) needled carbon fiber reinforced silicon-boron carbonitride (HC-CF/SiBCN) composites with a hierarchical A (CF)/B (HC)/C (SiBCN) structure were constructed and prepared for the first time by combining hydrothermal transformation and precursor infiltration and pyrolysis (PIP) process. The thickness of the HC coating controlled by the glucose concentration played a crucial role in tailoring the EMW capacity of the composite. The incorporation of SiBCN could not only effectively improve the oxidation resistance but also actively enhance the mechanical properties of the HC coated CF structure. Compared to the weak high-temperature oxidation resistance and mechanical properties of pristine 3D needled CF felt, the composites after the introduction of HC and SiBCN were thermostable in air atmosphere beyond 1000 °C to about above 70% weight retention, and the maximum flexural and compression strength of the composites could reach to 23.51 ± 1.37 and 12.22 ± 1.12 MPa, respectively. A substantial enhancement of EMW absorption ability was achieved through incorporation of HC and SiBCN, which could be attributed to the matched characteristic impedance and enhanced loss ability, whose optimization EMW absorption performance was the minimum reflection loss (RL_min) of -52.08 dB and effective absorption bandwidth (EAB) of 7.64 GHz for the composite obtained by two PIP cycles with 24 wt% glucose solution, demonstrating that the HC-CF/SiBCN composites with high-temperature stable, excellent mechanical and superior EMW absorption properties could be considered as a promising candidate for the applications in harsh environments.