Copper has been deposited on the surface of multiwailed carbon nanombes (MWNTs) and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer...Copper has been deposited on the surface of multiwailed carbon nanombes (MWNTs) and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), and electrochemical measurement. XRD analyses showed that Cu was a face-centered cubic (fcc) structure. The average size of Cu was calculated by Scherrer's formula from XRD data, and it was 11 nm. TEM revealed that Cu grains on the surface of MWNTs were uniform with the sizes of about 30-60 nm. The electrochemical measurement indicated that Cu-MWNT composite materials possessed fine electron conductivity.展开更多
This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes (MWCNTs) cartridge. Important parameters, such as the sample pH, eluent...This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes (MWCNTs) cartridge. Important parameters, such as the sample pH, eluent and its volume, sample flow rate and sample volume were investigated in detail. The linear ranges, the detection limits, and precisions (R.S.D.) were in the range of 0.1- 40 μg L^-11, 1.34.3 ng L^-1 and 2.3-2.8%, respectively. The performance of the proposed method was validated with real water samples, and the spiked recoveries were in the range of 91.7-117.8%, respectively. The experimental results demonstrated that the proposed method was an excellent alternative for the routine analysis of such pollutants in environmental samples. 2007 Qing Xiang Zhou. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristi...In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.展开更多
A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for...A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for fuel cell applications.The sizes of the supported Pt Ni nanoparticles are uniform and as small as 1–2 nm.Pt-to-Ni ratio was controllable by simply selecting a Pt Ni alloy target.The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation.The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst.The electronic structure characterization on the Pt Ni nanoparticles demonstrates that the electrons are transferred from Ni to Pt,which can suppress the CO poisoning effect.展开更多
Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall cou...Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions.展开更多
In the present study, multiwalled carbon nanotubes(MWCNTs), gold nanoparticles(AuN Ps), and glutathione(GSH) were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by la...In the present study, multiwalled carbon nanotubes(MWCNTs), gold nanoparticles(AuN Ps), and glutathione(GSH) were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by layer-by-layer technique as the films were constructed by the alternate deposition of cationic and anionic polyelectrolytes. The MWCNTs were modified via a noncovalent surface modification method using poly(diallydimethylammonium chloride) to form a cationic polyelectrolyte. An anionic polyelectrolyte was prepared by the chemical reduction of HAuCl_4 using sodium citrate as both the stabilizing and reducing agent to form anionic AuN Ps. GSH was used as an electrocatalyst toward the electro-oxidation of dopamine. The constructed composite electrode exhibits excellent electrocatalytic activity toward dopamine with a short response time and a wide linear range from 1 to 100 mmol/L. The limits of detection and quantitation of dopamine are(0.316 ± 0.081) mmol/L and(1.054 ± 0.081) mmol/L, respectively. The method is satisfactorily applied for the determination of dopamine in plasma and urine samples to obtain the recovery in the range from 97.90% to 105.00%.展开更多
This work focuses to improve the mechanical properties and investigates the growth of osteoblasts on a degradable chitosan/poly(L-lactide)/carbon nanotubes composite for tissue engineering. The morphological and mecha...This work focuses to improve the mechanical properties and investigates the growth of osteoblasts on a degradable chitosan/poly(L-lactide)/carbon nanotubes composite for tissue engineering. The morphological and mechanical properties characterizations were performed using scanning electronic microscopy (SEM) and rheometrics analysis system (RSA). Osteoblasts differentiation was determined by alkaline phosphatase activity, total number cells by an Alamar Blue assay, cell attachment and proliferation were visualized qualitatively using SEM, mineralization was characterized by transformed infrared spectroscopy, energy dispersive spectroscopy, and X-ray diffraction. The results suggest that the chitosan/poly(L-lactide)/multiwalled carbon nanotubes composites exhibit the ability to promote cell adhesion, proliferation, and differentiation on their surface.展开更多
A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as ...A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as the reversed dispersive sorbent.It was analyzed after purification by highperformance liquid chromatography,the extraction time and the properties of the nanocomposite were optimized.Under optimized conditions,present method has linear response over concentration range of 0.5–50 ng/mL in pork samples with a satisfactory detection limit close to 0.1 ng/mL.The precisions of the current method(coefficient of variation)are lower than 5%,while recoveries are more than 98.3%.The nanocomposite exhibited high adsorptivity,long-term storage stability,satisfactory anti-interfering activity and high selectivity toward2-agonists compared with those of rGO and CNTs.展开更多
In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in har...In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.展开更多
Synthesised triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNTs) were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs.T...Synthesised triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNTs) were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs.The adsorption capacity increased with an increase in pH for all adsorbents.The adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs,respectively.Both Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R 2 close to 1 for all adsorbents.On the other hand,the experimental data fitted well with a pseudo secondorder model.The speciation of nickel also influenced the adsorption on the purified and Tpp-MWCNTs.The adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature.展开更多
Thiosemicarbazide-grafted multi-walled carbon nanotubes were prepared and employed to investigate the pre-concentration of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) from aqueous solution prior to their determination by ICP-OES....Thiosemicarbazide-grafted multi-walled carbon nanotubes were prepared and employed to investigate the pre-concentration of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) from aqueous solution prior to their determination by ICP-OES. The resulting material was characterized by FT-IR, TGA and SEM. Various factors influencing the separation and pre-concentration were investigated. The enrichment factor typically is 60. Under optimized experimental conditions, the maximum adsorption capacities of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) were found to be 1.98, 10.94, 3.69 mg/g, and the relative standard deviations are 〈 3.5% (n = 6). The new adsorbent shows superior reusability and stability. The procedure was successfully applied to the determination of trace quantities of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) in water samples.展开更多
We have studied the effect of the engineered nanomaterial Taunit, containing multiwalled carbon nano- tubes (MWCNTs), on the growth of Onobrychis arenaria seedlings and investigated whether affected plants uptake an...We have studied the effect of the engineered nanomaterial Taunit, containing multiwalled carbon nano- tubes (MWCNTs), on the growth of Onobrychis arenaria seedlings and investigated whether affected plants uptake and accumulate MWCNTs. We found that 100 gg/mL and 1000 lag/mL of Taunit stimulated the growth of roots and stems, and enhanced the peroxidase activity in these parts of plants. Microscopy studies showed the presence of MWCNTs in the root and leaf tissues of seedlings exposed to Taunit, suggesting that MWCNTs have a capacity to penetrate the cell walls, accumulate in roots and translocate to the leaves. Thus the stimulating effect of MWCNTs on seedlings of O. arenaria may be associated with the primary uptake and accumulation of MWCNTs by plant roots followed by translocation to the other plant tissues.展开更多
A sensitive electrochemical sensor for the determination of cysteamine (CA) was developed using a modified multiwall carbon nanotube paste electrode (MWCNTPE) with isoproterenol (ISPT) as a mediator. This modifi...A sensitive electrochemical sensor for the determination of cysteamine (CA) was developed using a modified multiwall carbon nanotube paste electrode (MWCNTPE) with isoproterenol (ISPT) as a mediator. This modified electrode showed very high electrocatalytic activity for the anodic oxidation of CA. Under the optimized conditions, the electrocatalytic peak current showed a linear relationship with CA concentration in the range of 0.3-450.0 μmol/L with a detection limit of 0.09 μmol/L CA. The modified electrode was used for the determination of CA in real samples such as urine and drug samples.展开更多
Herein a facile and controllable heterocoagulation between polystyrene (PS) microspheres and multiwalled carbon nanotubes (MWCNTs) is introduced based on colloid thermodynamics. The MWCNTs play the role of steric ...Herein a facile and controllable heterocoagulation between polystyrene (PS) microspheres and multiwalled carbon nanotubes (MWCNTs) is introduced based on colloid thermodynamics. The MWCNTs play the role of steric stabilizer for stabilizing the metastable PS microspheres and thus immobilize spontaneously on the surface of PS microspheres. The synthesized MWCNTs-coated PS composite particles have been extensively characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetry and Raman spectroscopy. The results indicate that the structure and morphology of the resultant MWCNTs-coated PS composite particles are significantly affected by the weight ratio of PS and MWNCTs and the amount of poly(vinylpyrrolidone) that is injected into PS dispersion before they are mixed with MWCNTs. Therefore, these composite particles have the potential to produce MWCNTs-based composite materials with controllable mass loading and dispersity of MWCNTs.展开更多
MWCNTs-Co(II) and Pd(II) were prepared through grafting silylated-salicylaldimine Pd(II) and Co(II) on multiwalled carbon nanotubes(MWCNTs) for ethylene oligomerization. The structures of the two MWCNTs-supported cata...MWCNTs-Co(II) and Pd(II) were prepared through grafting silylated-salicylaldimine Pd(II) and Co(II) on multiwalled carbon nanotubes(MWCNTs) for ethylene oligomerization. The structures of the two MWCNTs-supported catalysts were characterized by means of scanning electron microscopy(SEM), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, thermogravimetric analyses(TGA) and nitrogen adsorption and desorption. And the influence of the supported pattern on the catalytic properties for ethylene oligomerization was investigated. The results revealed that the silylated-salicylaldimine complexes were grafted on the inner and outer surfaces of the carbon nanotubes and the pore size and BET surface area of MWCNTs decreased. Compared with the homogeneous catalysts, the two MWCNTs-supported catalysts had higher selectivity for hexene and 1-hexene in the presence of diethylaluminum chloride(DEAC) with a small molecule size due to confinement effect. MWCNTs-Pd exhi-bited higher activity and higher selectivity for C8+ olefin compared to MWCNTs-Co due to electronic factors. The catalytic activities of MWCNTs-Pd and MWCNTs-Co decreased from 24.18×105g·(mol Pd·h)–1 and 20.57×105g·(mol Co·h)–1 to 19.79×105g·(mol Pd·h)–1 and 13.14×105g·(mol Co·h)–1 after the third recycle reaction, respectively.展开更多
An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobi...An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.展开更多
Multiwalled carbon nanotubes ( MWNTs) were prepared by DCarc dischargein hydrogen gas, and werethermally purified byinfrared radiation in air. The morphology of pristineand purified MWNTs was observed by scanning ele...Multiwalled carbon nanotubes ( MWNTs) were prepared by DCarc dischargein hydrogen gas, and werethermally purified byinfrared radiation in air. The morphology of pristineand purified MWNTs was observed by scanning electron microscope ( SEM) , and the crys tallinestructureand perfection wereinvestigated by high resolution transmission electron mi croscope( HRTEM) and Raman spectrometer. Itcameto the conclusion thatthese MWNTs possessed a high degreeof graphitization and very narrow centralchannel(about1 0 nm indiameter) , giving risetotheappearanceof breathing modesfor MWNTs.展开更多
Composites formed from Polyacrylamide (PAAm)-Multiwalled carbon nanotubes (MWNTs) were prepared via free radical crosslinking copolymerization with different amounts of MWNTs varying in the range between 0.1 and 50 wt...Composites formed from Polyacrylamide (PAAm)-Multiwalled carbon nanotubes (MWNTs) were prepared via free radical crosslinking copolymerization with different amounts of MWNTs varying in the range between 0.1 and 50 wt%. The temperature variations of the elastic modulus, G of the PAAm-MWNT composite due to volume phase transition were measured by using tensile testing technique. The composite preserves the ability to undergo the volume phase transition and its elastic modulus and toughness (T) are found strongly dependent on temperature. It is observed that elastic modulus increased when temperature is increased from 30?C to 60?C. Toughness, however presented the reversed behavior versus temperature compare to the elastic modulus.展开更多
Solvent-free nanofluids hold promise for many technologically significant applications.The liquid-like behavior,a typical rheological property of solvent-free nanofluids,has aroused considerable interests.However,ther...Solvent-free nanofluids hold promise for many technologically significant applications.The liquid-like behavior,a typical rheological property of solvent-free nanofluids,has aroused considerable interests.However,there has been still lack of efficient methods to predict and control the liquid-like behavior of solvent-free nanofluids.In this paper,we propose a semi-discrete dynamic system with stochastic excitation describing the temperature change effects on the rheological property of multiwall carbon nanotubes(MWCNTs)modified by grafting sulfonic acid terminated organosilanes as corona and tertiary amine as canopy,which is a typical covalent-type solvent-free nanofluid system.The vibration of the grafting branches is simulated by employing a structure-preserving approach,and the shear force of grafting branches at the fixed end is computed subsequently.By taking the shear forces as an excitation acting on the MWCNTs,the axial motion of the MWCNTs is solved with the 7-point Gauss-Kronrod quadrature rule.The critical temperature associated with the appearance of the liquid-like behavior as well as the upper bound of the moving speed of the modified MWCNTs is determined,which can be used to predict and control the liquid-like behavior of the modified MWCNTs in engineering applications.展开更多
In this paper the effects of temperature on the radial breathing modes (RBMs) and radial wave propaga- tion in multiwall carbon nanotubes (MWCNTs) are inves- tigated using a continuum model of multiple elastic iso...In this paper the effects of temperature on the radial breathing modes (RBMs) and radial wave propaga- tion in multiwall carbon nanotubes (MWCNTs) are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.展开更多
基金This work was financially supported by the Natural Science Foundation of Guangdong Province, China (No. 04300695) and the Starting-up Research Foundation of Jinan University (No 51204022)
文摘Copper has been deposited on the surface of multiwailed carbon nanombes (MWNTs) and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), and electrochemical measurement. XRD analyses showed that Cu was a face-centered cubic (fcc) structure. The average size of Cu was calculated by Scherrer's formula from XRD data, and it was 11 nm. TEM revealed that Cu grains on the surface of MWNTs were uniform with the sizes of about 30-60 nm. The electrochemical measurement indicated that Cu-MWNT composite materials possessed fine electron conductivity.
基金This work was supported by the Creative Talented Person's Fund of Henan Province (No. [20051126);Natural Science Foundation of Henan Province (No. 072300460010);the Fund of Henan Normal University (No. 2006PL06);the grants from the Henan Key Laboratory for environmental pollution control.
文摘This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes (MWCNTs) cartridge. Important parameters, such as the sample pH, eluent and its volume, sample flow rate and sample volume were investigated in detail. The linear ranges, the detection limits, and precisions (R.S.D.) were in the range of 0.1- 40 μg L^-11, 1.34.3 ng L^-1 and 2.3-2.8%, respectively. The performance of the proposed method was validated with real water samples, and the spiked recoveries were in the range of 91.7-117.8%, respectively. The experimental results demonstrated that the proposed method was an excellent alternative for the routine analysis of such pollutants in environmental samples. 2007 Qing Xiang Zhou. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.
基金supported by the National Natural Science Foundation of China(No.61274019)the Soochow University-Western University Joint Centre for Synchrotron Radiation Research+1 种基金the Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for fuel cell applications.The sizes of the supported Pt Ni nanoparticles are uniform and as small as 1–2 nm.Pt-to-Ni ratio was controllable by simply selecting a Pt Ni alloy target.The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation.The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst.The electronic structure characterization on the Pt Ni nanoparticles demonstrates that the electrons are transferred from Ni to Pt,which can suppress the CO poisoning effect.
基金supported by the National Natural Science Foundation of China(No.20705016)State Key Laboratory of Electroanalytical Chemistry(No.2008009)China Postdoctoral Science Foundation(No.20080431213).
文摘Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions.
基金financially supported by the Faculty of Science,King Mongkut’s Institute of Technology Ladkrabang,Bangkok,Thailand(No.2558-02050067)
文摘In the present study, multiwalled carbon nanotubes(MWCNTs), gold nanoparticles(AuN Ps), and glutathione(GSH) were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by layer-by-layer technique as the films were constructed by the alternate deposition of cationic and anionic polyelectrolytes. The MWCNTs were modified via a noncovalent surface modification method using poly(diallydimethylammonium chloride) to form a cationic polyelectrolyte. An anionic polyelectrolyte was prepared by the chemical reduction of HAuCl_4 using sodium citrate as both the stabilizing and reducing agent to form anionic AuN Ps. GSH was used as an electrocatalyst toward the electro-oxidation of dopamine. The constructed composite electrode exhibits excellent electrocatalytic activity toward dopamine with a short response time and a wide linear range from 1 to 100 mmol/L. The limits of detection and quantitation of dopamine are(0.316 ± 0.081) mmol/L and(1.054 ± 0.081) mmol/L, respectively. The method is satisfactorily applied for the determination of dopamine in plasma and urine samples to obtain the recovery in the range from 97.90% to 105.00%.
文摘This work focuses to improve the mechanical properties and investigates the growth of osteoblasts on a degradable chitosan/poly(L-lactide)/carbon nanotubes composite for tissue engineering. The morphological and mechanical properties characterizations were performed using scanning electronic microscopy (SEM) and rheometrics analysis system (RSA). Osteoblasts differentiation was determined by alkaline phosphatase activity, total number cells by an Alamar Blue assay, cell attachment and proliferation were visualized qualitatively using SEM, mineralization was characterized by transformed infrared spectroscopy, energy dispersive spectroscopy, and X-ray diffraction. The results suggest that the chitosan/poly(L-lactide)/multiwalled carbon nanotubes composites exhibit the ability to promote cell adhesion, proliferation, and differentiation on their surface.
基金This study was financially supported by the Program of Technology Gansu Province(1309RTSA025,1009FTGA018,1306TTPA036).
文摘A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as the reversed dispersive sorbent.It was analyzed after purification by highperformance liquid chromatography,the extraction time and the properties of the nanocomposite were optimized.Under optimized conditions,present method has linear response over concentration range of 0.5–50 ng/mL in pork samples with a satisfactory detection limit close to 0.1 ng/mL.The precisions of the current method(coefficient of variation)are lower than 5%,while recoveries are more than 98.3%.The nanocomposite exhibited high adsorptivity,long-term storage stability,satisfactory anti-interfering activity and high selectivity toward2-agonists compared with those of rGO and CNTs.
文摘In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.
基金The Grant-Holder-Linked Bursary received from the National Research Foundation and the bursary granted by the Department of Chemical Technology to Mr. A. A
文摘Synthesised triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNTs) were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs.The adsorption capacity increased with an increase in pH for all adsorbents.The adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs,respectively.Both Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R 2 close to 1 for all adsorbents.On the other hand,the experimental data fitted well with a pseudo secondorder model.The speciation of nickel also influenced the adsorption on the purified and Tpp-MWCNTs.The adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature.
文摘Thiosemicarbazide-grafted multi-walled carbon nanotubes were prepared and employed to investigate the pre-concentration of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) from aqueous solution prior to their determination by ICP-OES. The resulting material was characterized by FT-IR, TGA and SEM. Various factors influencing the separation and pre-concentration were investigated. The enrichment factor typically is 60. Under optimized experimental conditions, the maximum adsorption capacities of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) were found to be 1.98, 10.94, 3.69 mg/g, and the relative standard deviations are 〈 3.5% (n = 6). The new adsorbent shows superior reusability and stability. The procedure was successfully applied to the determination of trace quantities of Cd(Ⅱ), Cu(Ⅱ) and Pb(Ⅱ) in water samples.
文摘We have studied the effect of the engineered nanomaterial Taunit, containing multiwalled carbon nano- tubes (MWCNTs), on the growth of Onobrychis arenaria seedlings and investigated whether affected plants uptake and accumulate MWCNTs. We found that 100 gg/mL and 1000 lag/mL of Taunit stimulated the growth of roots and stems, and enhanced the peroxidase activity in these parts of plants. Microscopy studies showed the presence of MWCNTs in the root and leaf tissues of seedlings exposed to Taunit, suggesting that MWCNTs have a capacity to penetrate the cell walls, accumulate in roots and translocate to the leaves. Thus the stimulating effect of MWCNTs on seedlings of O. arenaria may be associated with the primary uptake and accumulation of MWCNTs by plant roots followed by translocation to the other plant tissues.
基金Majlesi Branch,Islamic Azad University,Isfahan,Iran for their support
文摘A sensitive electrochemical sensor for the determination of cysteamine (CA) was developed using a modified multiwall carbon nanotube paste electrode (MWCNTPE) with isoproterenol (ISPT) as a mediator. This modified electrode showed very high electrocatalytic activity for the anodic oxidation of CA. Under the optimized conditions, the electrocatalytic peak current showed a linear relationship with CA concentration in the range of 0.3-450.0 μmol/L with a detection limit of 0.09 μmol/L CA. The modified electrode was used for the determination of CA in real samples such as urine and drug samples.
基金financially supported by the National Natural Science Foundation of China(Nos.21204030 and 51133002)the Fundamental Research Funds for the Central Universities(JUSRP111A05)
文摘Herein a facile and controllable heterocoagulation between polystyrene (PS) microspheres and multiwalled carbon nanotubes (MWCNTs) is introduced based on colloid thermodynamics. The MWCNTs play the role of steric stabilizer for stabilizing the metastable PS microspheres and thus immobilize spontaneously on the surface of PS microspheres. The synthesized MWCNTs-coated PS composite particles have been extensively characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetry and Raman spectroscopy. The results indicate that the structure and morphology of the resultant MWCNTs-coated PS composite particles are significantly affected by the weight ratio of PS and MWNCTs and the amount of poly(vinylpyrrolidone) that is injected into PS dispersion before they are mixed with MWCNTs. Therefore, these composite particles have the potential to produce MWCNTs-based composite materials with controllable mass loading and dispersity of MWCNTs.
基金supported by the Natural Science Foundation of Heilongjiang Province of China(No.E2018012)the Postdoctoral Foundation of Heilongjiang Province of China(No.16190023).
文摘MWCNTs-Co(II) and Pd(II) were prepared through grafting silylated-salicylaldimine Pd(II) and Co(II) on multiwalled carbon nanotubes(MWCNTs) for ethylene oligomerization. The structures of the two MWCNTs-supported catalysts were characterized by means of scanning electron microscopy(SEM), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, thermogravimetric analyses(TGA) and nitrogen adsorption and desorption. And the influence of the supported pattern on the catalytic properties for ethylene oligomerization was investigated. The results revealed that the silylated-salicylaldimine complexes were grafted on the inner and outer surfaces of the carbon nanotubes and the pore size and BET surface area of MWCNTs decreased. Compared with the homogeneous catalysts, the two MWCNTs-supported catalysts had higher selectivity for hexene and 1-hexene in the presence of diethylaluminum chloride(DEAC) with a small molecule size due to confinement effect. MWCNTs-Pd exhi-bited higher activity and higher selectivity for C8+ olefin compared to MWCNTs-Co due to electronic factors. The catalytic activities of MWCNTs-Pd and MWCNTs-Co decreased from 24.18×105g·(mol Pd·h)–1 and 20.57×105g·(mol Co·h)–1 to 19.79×105g·(mol Pd·h)–1 and 13.14×105g·(mol Co·h)–1 after the third recycle reaction, respectively.
基金Department of Science and Technology(DST)Government of India,for sanctioning financial assistance for executing this programme under Nanomaterials Science and Technology Initiative Programmethe Council of Scientific and Industrial Research(CSIR),Government of India,for granting her fellowship for executing this programme
文摘An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.
文摘Multiwalled carbon nanotubes ( MWNTs) were prepared by DCarc dischargein hydrogen gas, and werethermally purified byinfrared radiation in air. The morphology of pristineand purified MWNTs was observed by scanning electron microscope ( SEM) , and the crys tallinestructureand perfection wereinvestigated by high resolution transmission electron mi croscope( HRTEM) and Raman spectrometer. Itcameto the conclusion thatthese MWNTs possessed a high degreeof graphitization and very narrow centralchannel(about1 0 nm indiameter) , giving risetotheappearanceof breathing modesfor MWNTs.
文摘Composites formed from Polyacrylamide (PAAm)-Multiwalled carbon nanotubes (MWNTs) were prepared via free radical crosslinking copolymerization with different amounts of MWNTs varying in the range between 0.1 and 50 wt%. The temperature variations of the elastic modulus, G of the PAAm-MWNT composite due to volume phase transition were measured by using tensile testing technique. The composite preserves the ability to undergo the volume phase transition and its elastic modulus and toughness (T) are found strongly dependent on temperature. It is observed that elastic modulus increased when temperature is increased from 30?C to 60?C. Toughness, however presented the reversed behavior versus temperature compare to the elastic modulus.
基金supported by the National Natural Science Foundation of China(Nos.12172281 and 11972284)the Distinguished Young Scholars of Shaanxi Province of China(No.2019JC-29)+2 种基金the Foundation Strengthening Programme Technical Area Fund of Shaanxi Province of China(No.2021-JCJQ-JJ-0565)the Science and Technology Innovation Team of Shaanxi Province of China(No.2022TD-61)the Youth Innovation Team of Shaanxi Universities and Doctoral Dissertation Innovation Fund of Xi’an University of Technology of China(Nos.252072016 and 252072115)。
文摘Solvent-free nanofluids hold promise for many technologically significant applications.The liquid-like behavior,a typical rheological property of solvent-free nanofluids,has aroused considerable interests.However,there has been still lack of efficient methods to predict and control the liquid-like behavior of solvent-free nanofluids.In this paper,we propose a semi-discrete dynamic system with stochastic excitation describing the temperature change effects on the rheological property of multiwall carbon nanotubes(MWCNTs)modified by grafting sulfonic acid terminated organosilanes as corona and tertiary amine as canopy,which is a typical covalent-type solvent-free nanofluid system.The vibration of the grafting branches is simulated by employing a structure-preserving approach,and the shear force of grafting branches at the fixed end is computed subsequently.By taking the shear forces as an excitation acting on the MWCNTs,the axial motion of the MWCNTs is solved with the 7-point Gauss-Kronrod quadrature rule.The critical temperature associated with the appearance of the liquid-like behavior as well as the upper bound of the moving speed of the modified MWCNTs is determined,which can be used to predict and control the liquid-like behavior of the modified MWCNTs in engineering applications.
文摘In this paper the effects of temperature on the radial breathing modes (RBMs) and radial wave propaga- tion in multiwall carbon nanotubes (MWCNTs) are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.