Pretreated Carbon Fiber Research Articles

A Study on Applicability of Carbon Ceramic Disc using Pretreated Carbon Fiber

A Study on Applicability of Carbon Ceramic Disc using Pretreated Carbon Fiber

Time-Dependent Monitoring of Dopamine in the Brain of Live Embryonic Zebrafish Using Electrochemically Pretreated Carbon Fiber Microelectrodes.

Neurotransmitters are involved in functions related to signaling, stress response, and pathological disorder development, and thus, their real-time monitoring at the site of production is important for observing the changes related to these disorders. Here, we demonstrate the first time-dependent quantification of dopamine in the brains of live zebrafish embryos using electrochemically pretreated carbon fiber microelectrodes (CFMEs) utilizing differential pulse voltammetry as the measurement technique. The pretreatment of the CFMEs in 0.1 M NaOH held at a potential of +1.0 V for 600 s improves the sensitivity toward dopamine and allows for reliable measurements in low ionic strength media. We demonstrate the measurement of extracellular dopamine concentrations in the zebrafish brain during late embryogenesis. The extracellular dopamine concentration in the tectum of zebrafish varies between 200 and 400 nM. The conventional pharmacological manipulation of neurotransmitter levels in the brain demonstrates the selective detection of dopamine at the implantation site. Exposure to the dopamine transporter inhibitor nomifensine induces an increase in extracellular dopamine from 201.9 (±34.9) nM to 352.2 (±20.0) nM, while exposure to the norepinephrine transporter inhibitor desipramine does not lead to a significant modulation of the measured signal. Furthermore, we report the quantitative assessment of the catecholamine stress response of embryos to tricaine, an anesthetic frequently used in zebrafish assays. Exposure to tricaine induces a short-lived increase in brain dopamine from 198.6 (±15.7) nM to a maximum of 278.8 (±14.0) nM. Thus, in vivo electrochemistry can detect real-time changes in zebrafish neurochemical physiology resulting from drug exposure.

Spectroscopic analysis of chemically modified carbon fibres

Chemical treatments are used to introduce active functional groups and/or to increase the surface roughness of carbon fibres (CF) aiming to improve their interaction with polar polymeric matrices in composites. Considering the new challenges in the field of composite materials, such as the processing of hybrid composites and the growing use of thermoplastic structural composites, the modification of the CF surface has been increasingly studied. In this paper, the effect of various chemical treatments (with HCl, HNO3, H2SO4, CH3COOH, NH4OH, or H2O2) on the thermal stability, chemical composition, and microstructural parameters of a polyacrylonitrile‐based carbon fibre was investigated. Raman results indicated greater degree of crystallinity at the surface for the fibres treated (at 80°C for 1 h) with HCl, HNO3, H2SO4, and H2O2. The treatment with HCl at 80°C for 1 h was effective in reducing disturbance of the carbon structure, as indicated by the higher FWHMG value compared with those of the as‐received, acetone pretreated, and the other chemically treated carbon fibres. Fourier transform infrared (FTIR) showed that some treatments promoted an increase in CF polarity (H2SO4 at 80°C/1 h and NH4OH at 20°C/1 h), with the incorporation of organic polar groups (i.e., –OH). The apparent roughness of pretreated carbon fibre increased when treated with HNO3 at 80°C/1 h and H2SO4 at 80°C/1 h, as observed in the AFM analyses. AFM, FTIR, and Raman results suggest that the fibres treated with HNO3, H2SO4, and NH4OH were the most promising as reinforcement in high‐performance polymer composites.

Interfacial Bonding Enhancement Between Cryogenic Conditioned Carbon Fiber and Epoxy Resin Characterized by the Single-Fiber Fragmentation Method

Carbon fiber (CF) is an important structural material due to its favorable mechanical and physical properties. However, poor interfacial bonding with polymer resin severely affects the mechanical performance of carbon fiber reinforced polymer composites (CFRP). In this study, the single-fiber CFRPs were treated using multi-stage cryogenic approaches to optimize the interfacial shear strength (IFSS) between carbon fiber and epoxy resin. The carbon fiber was pretreated by cryogenic treatment with sharp and slow cooling rates, followed by the same treatment of the single-fiber CFRP composed of the pretreated carbon fiber to reach the optimal interfacial modification. The IFSS value was increased by 27.4% when the carbon fiber was pretreated at a slow cooling rate, and its single-fiber CFRP was treated at a sharp cooling rate.

Ferrocene-Incorporated Cobalt Sulfide Nanoarchitecture for Superior Oxygen Evolution Reaction.

Here, ferrocene(Fc)-incorporated cobalt sulfide (Cox Sy ) nanostructures directly grown on carbon nanotube (CNT) or carbon fiber (CF) networks for electrochemical oxygen evolution reaction (OER) using a facile one-step solvothermal method are reported. The strong synergistic interaction between Fc-Cox Sy nanostructures and electrically conductive CNTs results in the superior electrocatalytic activity with a very small overpotential of ≈304 mV at 10 mA cm-2 and a low Tafel slope of 54.2 mV dec-1 in 1 m KOH electrolyte. Furthermore, the Fc-incorporated Cox Sy (FCoS) nanostructures are directly grown on the acid pretreated carbon fiber (ACF), and the resulting fabricated electrode delivers excellent OER performance with a low overpotential of ≈315 mV at 10 mA cm-2 . Such superior OER catalytic activity can be attributed to 3D Fc-Cox Sy nanoarchitectures that consist of a high concentration of vertical nanosheets with uniform distribution of nanoparticles that afford a large number of active surface areas and edge sites. Besides, the tight contact interface between ACF substrate and Fc-Cox Sy nanostructures could effectively facilitate the electron transfer rate in the OER. This study provides valuable insights for the rational design of energy storage and conversion materials by the incorporation of other transition metal into metal sulfide/oxide nanostructures utilizing metallocene.

Improved atomic oxygen erosion resistance of the carbon fibre–epoxy interface with polyhedral oligomeric silsesquioxane

Polyhedral oligomeric silsesquioxane (POSS) was grafted onto the surface of carbon fibres (CFs) to fabricate carbon fibre/epoxy (CF/EP) composites with improved interlaminar shear strength (ILSS) and atomic oxygen (AO) erosion resistance. POSS-CF was prepared by reacting amine groups on the pretreated CF surface with the POSS to form a continuous uniform layer of siloxane oligomers. X-Ray photoelectron spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy demonstrated that POSS was successfully grafted onto the CF surface. The ILSS and AO erosion resistance of the POSS-treated CFs and CF-EP interface were improved because a SiO2 passivation layer formed with AO exposure, especially with POSS-EP0409. This is an effective solution for enhancing the interfacial bonding force and interfacial AO erosion resistance for the low-Earth orbit environment.

Interface improvement of carbon fiber/PMMA resin composites by fiber surface coating

The surface of the carbon fiber (CF) has been pretreated by liquid phase deposition of microcrystalline cellulose (MCC).X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM) have beenused to analyze and characterize the surface morphology and structure of carbon fiber, and the shear strength test and SEMobservation of single fiber interface have been performed. The interfacial adhesion properties of carbon fiber compositeshave been investigated. The results have shown that the pretreated carbon fiber deposition increases the shear strength of thesingle fiber interface by 259.3%. The analysis results have shown that the improvement of interfacial shear strength has beenrelated to the mechanical riveting between the fibers/resin and the force of the interface. Pretreatment has increased thecarboxyl groups on the surface of carbon fibers and forms hydrogen bonds between carboxyl groups, thereby improving theinterfacial properties of carbon fiber composites.

Complementary analytical imaging techniques for the characterization of pretreated carbon fiber reinforced plastics

In this work the complementary characterization of pretreatment techniques for adhesive bonding of carbon fiber reinforced plastics (CFRP) is presented. Industrial CFRP plates were pretreated with laser, plasma, and corundum blasting abrasive techniques followed by chemical activation. The combined use of atomic force microscopy and chemical force microscopy enabled the characterization of the surface morphology and the specific adhesion force between a chemically functionalized cantilever and the pretreated surfaces simulating the adhesive bond. Complementary measurements with scanning electrochemical microscopy and X-ray photoelectron spectroscopy supported the experimental findings and delivered additional information about the chemical structure of the surfaces. A comparison of experimental data of mechanical tensile shear strength measurements and the applied analytical methods revealed a valid correlation of microscopic and macroscopic techniques.

Selective Amperometric Recording of Endogenous Ascorbate Secretion from a Single Rat Adrenal Chromaffin Cell with Pretreated Carbon Fiber Microelectrodes.

Quantitative description of ascorbate secretion at a single-cell level is of great importance in physiological studies; however, most studies on the ascorbate secretion have so far been performed through analyzing cell extracts with high performance liquid chromatography, which lacks time resolution and analytical performance on a single-cell level. This study demonstrates a single-cell amperometry with carbon fiber microelectrodes (CFEs) to selectively monitor amperometric vesicular secretion of endogenous ascorbate from a single rat adrenal chromaffin cell. The CFEs are electrochemically pretreated in a weakly basic solution (pH 9.5), and such pretreatment essentially enables the oxidation of ascorbate to occur at a relatively low potential (i.e., 0.0 V vs Ag/AgCl), and further a high selectivity for ascorbate measurement over endogenously existing electroactive species such as epinephrine, norepinephrine, and dopamine. The selectivity is ensured by much larger amperometric response at the pretreated CFEs toward ascorbate over those toward other endogenously existing electroactive species added into the solution or ejected to the electrode with a micropuffer pipet, and by the totally suppressed current response by adding ascorbate oxidase into the cell lysate. With the pretreated CFE-based single-cell amperometry developed here, exocytosis of endogenous ascorbate of rat adrenal chromaffin cells is directly observed and ensured with the calcium ion-dependent high K+-induced secretion of endogenous ascorbate from the cells. Moreover, the quantitative information on the exocytosis of endogenous ascorbate is provided.

Studies of the electrochemical behavior of moniliformin mycotoxin and its sensitive determination at pretreated glassy carbon electrodes in a non-aqueous medium

The electrochemical oxidation of moniliformin (MON) mycotoxin in acetonitrile (ACN)+0.1moldm−3 (C4H9)4NPF6 at electrochemically pretreated glassy carbon electrodes (EPGCE) and fiber disk carbon ultramicroelectrodes (FCUME) is studied for the first time. Electrochemical techniques used were cyclic (CV), convolution and square wave (SWV) voltammetries as well as controlled potential electrolysis. Experimental results allowed inferring a complex electro-oxidation mechanism with adsorption of reactant and homogeneous chemical steps coupled to the electron transfer reaction.The UV–Vis spectroscopy was used as a non-electrochemical technique in order to follow the disappearance/appearance of the reactant/reaction product/s during controlled potential electrolysis.The most probable electro-oxidation mechanism proposed on the base of digital simulation results of cyclic voltammograms is one of the CEC type. Thermodynamic and kinetics parameters were calculated from the fitting of experimental cyclic voltammograms, while the diffusion parameter was calculated from convoluted cyclic voltammograms. We propose that reaction products obtained are produced through the decomposition of the MON radical generated from the electrochemical oxidation of MON anion.On the other hand, the MON quantitative determination was performed using adsorptive SWV at EPGCE. An extremely low detection limit of 1×10−11moldm−3 (1.2ppt) for a signal to noise ratio of 3:1 was calculated.

Effect of surface preparation on electroless Ni‐P plating on carbon fiber‐Reinforced Cyanate Ester Resin Laminate

The effect of surface preparation on electroless Ni‐P plating on carbon fiber reinforced cyanate ester resin laminate has been investigated. Three different surface chemical etching ways were performed, namely: (i) hexanediamine etching, (ii) hexanediamine followed by aniline etching, and (iii) aniline etching. The results indicated that Ni‐P coating on hexanediamine etching or hexanediamine followed by aniline etching pretreated carbon fiber reinforced cyanate ester resin laminates usually tended to be cracked, veined, and low adhesion, while aniline etched laminates showed a homogenous roughing surface which is suitable for subsequently uniform, cellular, and good adhesion Ni‐P plating. POLYM. COMPOS., 37:1161–1166, 2016. © 2014 Society of Plastics Engineers

HPLC–ED of low-molecular weight brominated phenols and tetrabromobisphenol A using pretreated carbon fiber microelectrode

Electrochemically pretreated carbon fiber microelectrode was used to develop a simple, fast and sensitive HPLC-ECD method for the determination of brominated phenols. In addition to simple mono-, di- and tri-bromophenols (4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, 2,4,6-tri-bromophenol) the possibility of electrochemical detection of 3,3',5,5'-tetrabromobisphenol A in oxidation mode is reported for the first time. The isocratic separation was achieved within 14 min using ternary mobile phase consisting of 50mM-phosphate buffer (pH 3.5), acetonitrile and methanol (35/15/50, v/v), and detection potential of E=+1450 mV (vs. Ag/AgCl). The carbon fiber microelectrode permitted to use high anodic potentials (up to +1800 mV vs. Ag/AgCl), the optimum analytical response was achieved at +1450 mV vs. Ag/AgCl. The limits of detection (LOD) for the studied analytes were within the range of 1.8-56.6 ng mL(-1). The developed method was applied to determination of brominated phenols in spiked water samples. Furthermore, after simple extraction with methyl tert-butyl ether, it was possible to quantify tetrabromobisphenol A (TBBA) in a piece of CRT monitor plastic casing. The found amount of TBBA was 10.22 mg kg(-1) (±0.43).

Influence of melatonin or its antagonism on alcohol consumption in ethanol drinking rats: A behavioral and in vivo voltammetric study

Melatonin, an indoleamine hormone synthesized in the pinealocytes, has been implicated as influencing the intake of alcohol in rats. It has been shown that this hormone is voltammetrically electroactive at the surface of pretreated carbon fiber microelectrodes in vitro and in vivo, in rat cerebral melatonergic regions such the pineal gland. The aim of this work consisted in the study of the influence of melatonin on spontaneously ethanol drinking or ethanol avoiding rats selected throughout a free choice two bottle test. It appeared that only the water preferring rats were affected by treatment with the hormone and that in vivo voltammetric related levels of melatonin were higher in the pineal gland of ethanol drinking rats versus water preferring rats. In addition, when treated with the melatonin antagonist GR128107 ethanol drinking rats significantly reduced the spontaneous consumption of alcohol.

Specific Oxygen-Containing Functional Groups on the Carbon Surface Underlie an Enhanced Sensitivity to Dopamine at Electrochemically Pretreated Carbon Fiber Microelectrodes

The in vivo use of carbon-fiber microelectrodes for neurochemical investigation has proven to be selective and sensitive when coupled with background-subtracted fast-scan cyclic voltammetry (FSCV). Various electrochemical pretreatments have been established to enhance the sensitivity of these sensors; however, the fundamental chemical mechanisms underlying these enhancement strategies remain poorly understood. We have investigated an electrochemical pretreatment in which an extended triangular waveform from -0.5 to 1.8 V is applied to the electrode prior to the voltammetric detection of dopamine using a more standard waveform ranging from -0.4 to 1.3 V. This pretreatment enhances the electron-transfer kinetics and significantly improves sensitivity. To gain insight into the chemical mechanism, the electrodes were studied using common analytical techniques. Contact atomic force microscopy (AFM) was used to demonstrate that the surface roughness was not altered on the nanoscale by electrochemical pretreatment. Raman spectroscopy was utilized to investigate oxide functionalities on the carbon surface and confirmed that carbonyl and hydroxyl functional groups were increased by electrochemical conditioning. Spectra collected after the selective chemical modification of these groups implicate the hydroxyl functionality, rather than the carbonyl, as the major contributor to the enhanced electrochemical signal. Finally, we have demonstrated that this electrochemical pretreatment can be used to create carbon microdisc electrodes with sensitivities comparable to those associated with larger, conventionally treated cylindrical carbon fiber microelectrodes.

Mechanical Properties of C/SiC Composites via Precursor Pyrolysis with Pretreated Carbon Fiber

3D C/SiC composites were fabricated by polycarbosilane (PCS) infiltration and pyrolysis process. The influence of pretreatment of carbon fiber, including pyrolytic carbon coating and thermal treatment, on mechanical properties of C/SiC composites was investigated. The results showed that the composites without fiber pretreatment had a flexural strength of 154MPa and a fracture toughness of 4.8 MPa•m1/2, while those with carbon coating or thermal treatment had much higher strength and toughness, that is, more than 400MPa and 15MPa•m1/2 respectively. Weak interfacial bonding and better in-situ strength of carbon fiber were main reasons for mechanical property improvement with pretreated carbon fiber.

Micro-cylinder biosensors for phenol and catechol based on layer-by-layer immobilization of tyrosinase on latex particles: Theory and experiment

Abstract Microelectrode sensors for phenol and catechol are described, based on the sequential immobilization of polystyrene sulphonate, polyallylamine, tyrosinase and polyallylamine again, onto micrometer scale latex spheres, followed by the adsorption of the spheres onto electrochemically pretreated carbon fibres. The steady state responses of the fibres are analyzed in terms of a cylindrical diffusion – kinetic model. It is deduced that the adsorbed latex particles provide a relatively open film structure, resulting in a diffusion coefficient only one order of magnitude lower than the solution value, and that at minimum 2–3% of the immobilized enzyme is catalytically active. The optimised sensors exhibit linear ranges to phenol and catechol of 7–56.5 μM and 2–19.7 μM respectively, with sensitivities of 0.15 A M−1 cm−2 and 1.72 A M−1 cm−2 respectively. The limiting factor to sensor stability is desorption of latex from the fibres.

Studies on the Development of Microelectrodes and Miniaturized Biosensors with A Novel Material: Petroleum Pitch-Based Carbon Fiber

This article reports the experimental results of the studies of a carbon fiber microelectrode and therefore a miniaturized biosensor. The important progress that resulted from the use of oxidation pretreated petroleum pitch-based carbon fiber (PPCF) is described. The pretreatment on the PPCF microelectrode resulted in obvious improvement of its properties. The peak-shaped voltammograms are similar to that of a common-sized electrode, and the currents are higher than the nonpretreated one for several (even tens) folds due to the high dense surficial active centers as oxo acid and peroxide acid. The thionine is easily polymerized on the pretreated PPCF microelectrode, and as a matrix electrode, a miniaturized amperometric biosensor for catechol was developed by immobilization of a mushroom extract on it. The resulting biosensor could be applied to determine the catechol with a linear range of 1.0 × 10−7–1.0 × 10−5 mol/L and response time less than 50 s.

Determination of the neurotransmitter-norepinephrine in the presence of ascorbic acid using carbon fiber microelectrodes activated by potentiostat

Carbon fiber microelectrodes pretreated electrochemically exhibit highly electrochemical activity and show high sensitivity for determining of the neurotransmitter-norepinephrine in the presence of high concentrations of ascorbic acid. The peak currents are a linear relationship with norepinephrine in the range of 639×10−6–1.06×10−4 mol/l and the detection limit is up to 2.0×10−6 mol/l. All analytical processes can be performed without deaeration. It is possible to use the electrochemically pretreated carbon fiber microelectrodes in determining norepinephrine in vivo directly.

Effect of local infusion of glutamate analogues into the nucleus accumbens of rats: an electrochemical and behavioural study

In vivo voltammetry at electrochemically pretreated carbon fibre electrodes was used to investigate the effect of local infusion of glutamate analogues on dopamine (DA) release in rat nucleus accumbens. Infusion of a low dose of NMDA or AMPA (1 mM/0.2 μl), but not l-glutamate or kainate, was followed a few minutes later by a large but short-lived increase in the extracellular concentration of DA. The involvement of spreading depression was indicated since this response could be repeated only after a short refractory period, and the response magnitude did not seem to be dependent on the dose infused. Furthermore, the increase in DA release was accompanied by a marked negative shift in brain field potential and a similar increase in release could be induced by local infusion of K +. The infusion of NMDA, AMPA or kainate was followed by behavioural activation of the animals but not convulsions. The behavioural response induced by NMDA was dose-dependently reduced by haloperidol, which suggests the involvement of a DA-dependent mechanism in this effect. Co-infusion of the DA transport inhibitors, nomifensine or GBR 12909, failed to alter the DA response to NMDA, while this response was completely blocked by co-infusion of tetrodotoxin or pretreatment with reserpine. It is evident from this study that local infusion of NMDA or AMPA may induce spreading depression in rat nucleus accumbens and that this condition is associated with a vast release of DA and behavioural activation.

Filamentary preforms of Al-13wt % Si alloy reinforced with TiC-coated and pre-treated carbon fibres

Filamentary preforms of aluminium-13 wt % Si alloy reinforced with TiC-coated carbon fibres were obtained by liquid metal infiltration using K2ZrF6 as wetting agent. The interfacial structure was investigated using analytical electron microscopy (TEM, SEM) and the fibre strength measured following each step of processing. The reaction between the K2ZrF6 deposit and the molten alloy is discussed on the basis of the reaction products formed at the fibre-matrix interface, which mainly consisted of fluoride compounds (K3AlF6), different zirconium-rich suicides (Si2Zr, SiZr (Al), (Al, Si)2Zr) and crystalline γ-alumina. Large amounts and/or inhomogeneous distributions of the K2ZrF6 deposit should be avoided, because the massive precipitation of colonies of intermetallics around fibres is conducive for the formation of harmful aluminium carbides and favours brittle fracture of the composite. The utilization of TiC-coatings formed by the reactive chemical vapour deposition process gave satisfactory results, both in terms of composite elaboration and fibre protection during liquid infiltration.