Carbon fibers modified with carbon nanoparticles by a facile and fast flame preparation for in-tube solid-phase microextraction

Carbon fibers (CFs) were modified with carbon nanoparticles (CNPs) by a facile and fast flame preparation method. CNPs-CFs were observed by scanning electron microscope, and the nano-scaled granular structure on the surface was found. This material was also characterized by Raman microscope and X-ray photoelectron spectroscope. It was placed into a polyetheretherketone tube to get an extraction tube, which was connected with high performance liquid chromatography for online analysis. The tube displayed the effective extraction to several polycyclic aromatic hydrocarbons (PAHs), based on the possible hydrophobic and π stacking mechanism. Under the optimized conditions (60 mL of sample volume, 2.00 mL min^?1 of sample rate, 0.5% of methanol in sample, 2.0 min of desorption time), an analytical method towards these PAH targets was established. The low limits of detection (0.001–0.005 μg L^?1), satisfactory linear ranges (0.003–5.0 μg L^?1, 0.003–10.0 μg L^?1) and efficient enrichment factors (1012–3164) were presented. The method was applied to detect trace targets in several water samples and satisfactory results were obtained. The method provided some superiorities over other analytical methods, like online test, shorter time and better sensitivity.     

Cellulose fibers modified with silver nanoparticles

Cellulose fibers modified with silver nanoparticles were prepared using N-methylmorpholine-N-oxide as a direct solvent and analyzed in this study. Silver nanoparticles were generated as a product of AgNO₃ reduction by means of three methods under varying light conditions (daylight and darkroom). Influence of generating conditions on the size, the type and the number weighting of created nanoparticles was examined. Dynamic Light Scattering technique (DLS) was used for determination of those parameters. DLS analysis showed that the best method, i.e. the one that allowed the generation of the greatest number of silver nanoparticles with the smallest diameter and the smallest agglomerates, was incubation of cellulose pulp with AgNO₃ in a darkroom for 24 h. Mechanical and hydrophilic properties of all obtained fibers were also determined. Results showed that the method of silver nanoparticles generation did not influence significantly mechanical and hydrophilic properties of the modified fibers, because in all cases only small decreases of the studied parameters were observed.     

Cellulose fibers modified by Eu3+-doped yttria-stabilized zirconia nanoparticles

This paper describes a method for manufacturing luminescent cellulose fibers. Good optical properties of cellulose fibers under UV-C illumination were achieved by incorporating ZrO₂ (0.5?mol% of Eu³⁺) stabilized by Y₂O₃ (7?mol%) into the fiber structure’s particles. Fibers were obtained from 8?wt% cellulose solution in N-methylmorpholine N-oxide (NMMO) with the addition of a luminescent modifier in the range between 0.5 and 10?wt%. The physico-chemical and mechanical parameters and the structure of these fibers were examined.     

Multifunctional PES fabrics modified with colloidal Ag and TiO2 nanoparticles

This study is aimed to highlight the possibility of engineering the multifunctional textile nanocomposite material based on the polyester (PES) fabric modified with colloidal Ag and TiO₂ nanoparticles (NPs). The effects of concentration of NPs as well as the order of Ag and TiO₂ NPs loading on antimicrobial, UV protective, and photocatalytic properties of PES fabrics were examined. The antimicrobial activity of differently modified PES fabrics was tested against Gram‐negative bacterium Escherichia coli, Gram‐positive bacterium Staphylococcus aureus, and fungus Candida albicans. The concentration of Ag colloid and the order of Ag and TiO₂ NPs loading considerably affected the antimicrobial efficiency of PES fabrics. The fabrics provided maximum UV protection upon surface modification with Ag and TiO₂ NPs. Ag NPs enhanced Ag NPs enhanced the photodegradation activity of TiO₂ NPs and total photodegradation of methylene blue was achieved after 24 hr of UV illumination. Copyright © 2010 John Wiley & Sons, Ltd.     

Glucose biosensors based on Ag nanoparticles modified TiO2 nanotube arrays

A GOx/Ag/TiO₂ glucose biosensor was achieved by photoreducing Ag nanoparticles on TiO₂ nanotube arrays (NTAs) following with adsorption of GOx. The morphology, structure, and element component of Ag/TiO₂ NTAs were characterized by scanning electron microscope, transmission electron microscope, and X-ray diffraction. Ag nanoparticles were uniformly deposited on surface of TiO₂ NTAs with average size of 15 nm and the size and distribution changed with the immersing time of TiO₂ NTAs in AgNO₃ aqueous solution. Electrochemical properties of Ag/TiO₂ NTAs were characterized by cyclic voltammetry and amperometric detection of H₂O₂, revealing that TiO₂ NTAs with immersing time of 30 min achieve the best electrochemical activity. The GOx/Ag/TiO₂ NTAs biosensor with optimum conditions achieves a sensitivity of 0.39μA mM^?1 cm^?2 with liner range from 0.1 to 4 mM.     

Polyoxadiazole fibers modified by nano-additives

A method of increasing the oxygen index (OI) of polyoxadiazole fibers by introducing fire retardant nano(micro)-additives into the polymer before the fiber formation is presented. The following additives are studied: dicarboxydiphenyl oxide, brominated and chlorinated phthalocianines, and carbon black. The use of these additives in the amount of 2–5% of the polymer weight in spinning solutions makes it possible to produce fibers with OI of up to 34 % and thermal stability of up to 84%.     

Facile preparation and characterization of highly antimicrobial colloid Ag or Au nanoparticles

A series of colloid silver or gold nanoparticles (AgNPs or AuNPs) were successfully prepared by in situ reduction and stabilization of hyperbranched poly(amidoamine) with terminal dimethylamine groups (HPAMAM-N(CH(3))(2)) in water, and they all exhibited highly antimicrobial activity. The particle size could be controlled easily by adjusting the molar ratio of N/Ag (or N/Au) in feed. When the molar ratio was 2, some aggregates of the nanoparticles separated from the colloidal solution, which showed some limited antimicrobial activity with the bacterial inhibition ratio of below 15%. As the molar ratio increased from 10 to 30, the average particle diameters decreased (from ca. 7.1 to 1.0 nm for AgNPs and from ca. 7.7 to 3.9 nm for AuNPs, respectively) and they all showed high dispersion stability and excellent antimicrobial efficiency. All the bacterial inhibition ratios reached up to ca. 98% at the low silver content of ca. 2.0 microg/mL or at the low gold content of ca. 2.8 microg/mL. The AgNPs or AuNPs with smaller particle size can provide much more effective contact surface with the bacteria, thus enhancing their antimicrobial efficiency. Besides, the cationic HPAMAM-N(CH(3))(2) can also do some contribution to the antimicrobial activity through the strong ionic interaction with the bacteria.     

Novel method for the preparation of core-shell nanoparticles with movable Ag core and polystyrene loop shell

Core/shell nanoparticles with movable silver (Ag) core and polystyrene (PSt) shell (Ag@PSt nanoparticle) were successfully synthesized at room temperature and under ambient pressure via two steps: γ-irradiation and interfacial-initiated polymerization. Firstly, mono-dispersed Ag nanoparticles with diameters 20 nm were synthesized in inversed microemulsion by reducing silver nitrate under γ-irradiation. Then, Ag nanoparticles were coated with PSt via interfacial-initiated polymerization with cumene hydroperoxide/ferrous sulfate/disodium ethylenediaminetetraacetate/sodium formaldehyde sulfoxylate (CHPO-Fe²⁺-EDTA-SFS) as the redox initiation pair. The resulted Ag@PSt nanoparticles were identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).     

One-pot preparation of surface modified boehmite nanoparticles with rare-earth cyclen complexes

We report on the one-pot synthetic procedure of cyclen derivatives bearing three acetate groups attached on boehmite nanoparticles, the complexing capabilities of these inorganic-organic hybrid materials with rare earth cations, and the behaviour as contrast agents or fluorescence probes.     

Ag nanoparticles for determination of bisphenol A by resonance light-scattering technique

Resonance light-scattering (RLS) technique was developed for studying the interaction of silver nanoparticles (Ag NPs) with bisphenol A. A simple and environmentally friendly method was developed to synthesize Ag NPs using cinnamon extract. Synthesized nanoparticles were characterized using various measurement techniques. The synthesized Ag NPs were nearly spherical, with the sizes ranging from 30 to 60 nm. Spectral analysis indicated that the cinnamon extract acted as the reducing and capping agents on the surface of Ag NPs. RLS technique was used as the detection method. Light-scattering properties of the synthesized nanoparticles in the presence or absence of bisphenol A was selected as the detection signal. Under the optimal conditions, the linear dynamic range and RSD were found to be 0.01–10.0 mg L^?1 and 2.78% (n?=?3), respectively. A limit of detection of 0.005 mg L^?1 was obtained for the determination of bisphenol A. The obtained results showed successful application of the method for the analysis of bisphenol A in real samples.     

Characterization of wood fibers modified by phenol-formaldehyde

Wood-fiber phenol-formaldehyde-resin (PFR) modified surfaces, obtained from the adsorption of a PFR/water solution, are investigated as a function of the nature and the amount of PFR adsorbed. Surface are measurements are performed by using krypton adsorption at 77 K. Chemical modification is monitored by the electron spectroscopy for chemical analysis (ESCA) technique and the surface energy by the inverse phase gas chromatography (IPGC) method at infinite dilution. The London dispersive componentγ _S ^L of the surface energy shows a relationship to the concentration of carbon and oxgen at the fiber surface.γ _S ^L increases from 27.5 mN·m⁻¹ for the untreated fiber to 42.5 mN·m⁻¹ for the fibers treated with 20% high molecular-weight-grade phenol-formaldehyde. The surface atomic ratio O/C determined using the ESCA technique exhibits a decrease from 44% for untreated to 31% for treated samples. Surface area also decreases from 2.09 m²/g to 1.50 m²/g. The PFR adsorbed by wood fibers is observed as the dispersive component of surface energy starts to increase, as the surface oxygen concentration decreases, and on the surface area of the wood fiber.     

Study on the preparation and formation mechanism of barium sulphate nanoparticles modified by different organic acids

This paper reports a simple method to prepare barium sulphate nanoparticles by use of tetradecanoic acid, hexadecanoic acid and stearic acid as modifier. The barium sulphate nanoparticles obtained are characterized by using Fourier transform infra-red spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic laser light scatter (DLLS) and thermogravimetric analysis (TGA), respectively. The results show that the BaSO₄ particles are all spherical and in the nano-scale. Our method has a better dispersion and controllable diameter dependent on the length of the chain of organic acid and the pH value of the system. A possible mechanism is also discussed.     

Spectroscopy property of Ag nanoparticles

Three silver nanoparticles of different size characterized by the UV-vis absorbance spectra and TEM images were prepared by citrate reduction and laser ablation with excitation of 532 and 248 nm. It is proved that all of them are effective SERS-active substrates, whereas, enhancement effect of silver colloids has not too much relation with the size and shape of the Ag nanoparticles. However, different photoluminescence spectra were observed from these three particles, indicating that the photoluminescence property of silver nanoparticles is dependent on the size. The spectra shift to higher energies with decreasing particle size. In addition, we also tentatively give the assignment of the luminescence bands.     

Electrode modified with a composite film of ZnO nanorods and Ag nanoparticles as a sensor for hydrogen peroxide

A conducting fluorine-doped tin oxide (FTO) electrode, first modified with zinc oxide nanorods (ZnONRs) and subsequently attached with photosynthesized silver nanoparticles (AgNPs), designated as AgNPs/ZnONRs/FTO electrode, was used as an amperometric sensor for the determination of hydrogen peroxide. The first layer (ZnONRs) was obtained by chemical bath deposition (CBD), and was utilized simultaneously as the catalyst for the photoreduction of Ag ions under UV irradiation and as the matrix for the immobilization of AgNPs. The aspect ratio of ZnONRs to be deposited was optimized by controlling the number of their CBDs to render enough surface area for Ag deposition, and the amount of AgNPs to be attached was controlled by adjusting the UV-irradiation time. The immobilized AgNPs showed excellent electrocatalytic response to the reduction of hydrogen peroxide. The resultant amperometric sensor showed 10-fold enhanced sensitivity for the detection of H₂O₂, compared to that without AgNPs, i.e., only with a layer of ZnONRs. Amperometric determination of H₂O₂ at −0.55 V gave a limit of detection of 0.9 μM (S/N = 3) and a sensitivity of 152.1 mA M⁻¹ cm⁻² up to 0.983 mM, with a response time (steady-state, t₉₅) of 30-40 s. The selectivity of the sensor was investigated against ascorbic acid (AA) and uric acid (UA). Energy dispersive X-ray (EDX) analysis, transmission electron microscopic (TEM) image, X-ray diffraction (XRD) patterns, cyclic voltammetry (CV), and scanning electron microscopic (SEM) images were utilized to characterize the modified electrode. Sensing properties of the modified electrode were studied both by CV and amperometric analysis.     

Study of the physicochemical properties of aminostyrene copolymers modified by plasma treatment

The change in the surface and mechanical properties of styrene-butyl methacrylate-aminostyrene terpolymer films by plasma treatment was investigated. It was found that treatment in a direct-current discharge enhanced the mechanical strength of the terpolymer surface, which can be associated with the crosslinking of linear macromolecules into a three-dimensional network structure. It was shown that the most substantial changes in the mechanical strength are achieved in the case of terpolymer film treatment at the anode.     

Ag nanoparticles from the mechanochemical decomposition of Ag oxalate

The present work focuses on the chemical reactivity of Ag oxalate powders under mechanical processing conditions. The powders were submitted to mechanical loads in the presence of an aqueous solution containing a polymeric surfactant. A gradual decrease of the total mass of powders was observed, ascribable to the occurrence of a decomposition process. X-ray diffraction and UV-vis spectrophotometric analyses indicated that the Ag oxalate decomposes into metallic Ag and gaseous carbon dioxide. Transmission electron microscopy showed that metallic Ag exists in the form of particles with average size of about 5 nm. The formation of nanometer-sized Ag particles can be related to the plastic deformation and attrition processes taking place at the points of contacts between neighboring particles during the mechanical loading at collision.     

Polypropylene film chemical and physical modifications by dielectric barrier discharge plasma treatment at atmospheric pressure

Dielectric barrier discharge (DBD) technologies have been used to treat a polypropylene film. Various parameters such as treatment speed or electrical power were changed in order to determine the treatment power impact at the polypropylene surface. Indeed, all the treatments were performed using ambient air as gas to oxidize the polypropylene surface. This oxidation level and the surface modifications during the ageing were studied by a wetting method and by X-ray photoelectron spectroscopy (XPS). Moreover polypropylene film surface topography was analyzed by atomic force microscopy (AFM) in order to observe the surface roughness modifications. These topographic modifications were correlated to the surface oxidation by measuring with a lateral force microscope (LFM) the surface heterogeneity. The low ageing effects and the surface reorganization are discussed.