Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 640
Filtrar
1.
Molecules ; 26(3)2021 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-33499359

RESUMEN

Carbonized elastomer-based composites (CECs) possess a number of attractive features in terms of thermomechanical and electromechanical performance, durability in aggressive media and facile net-shape formability, but their relatively low ductility and strength limit their suitability for structural engineering applications. Prospective applications such as structural elements of micro-electro-mechanical systems MEMS can be envisaged since smaller principal dimensions reduce the susceptibility of components to residual stress accumulation during carbonization and to brittle fracture in general. We report the results of in situ in-SEM study of microdeformation and fracture behavior of CECs based on nitrile butadiene rubber (NBR) elastomeric matrices filled with carbon and silicon carbide. Nanostructured carbon composite materials were manufactured via compounding of elastomeric substance with carbon and SiC fillers using mixing rolling mill, vulcanization, and low-temperature carbonization. Double-edge notched tensile (DENT) specimens of vulcanized and carbonized elastomeric composites were subjected to in situ tensile testing in the chamber of the scanning electron microscope (SEM) Tescan Vega 3 using a Deben microtest 1 kN tensile stage. The series of acquired SEM images were analyzed by means of digital image correlation (DIC) using Ncorr open-source software to map the spatial distribution of strain. These maps were correlated with finite element modeling (FEM) simulations to refine the values of elastic moduli. Moreover, the elastic moduli were derived from unloading curve nanoindentation hardness measurements carried out using a NanoScan-4D tester and interpreted using the Oliver-Pharr method. Carbonization causes a significant increase of elastic moduli from 0.86 ± 0.07 GPa to 14.12 ± 1.20 GPa for the composite with graphite and carbon black fillers. Nanoindentation measurements yield somewhat lower values, namely, 0.25 ± 0.02 GPa and 9.83 ± 1.10 GPa before and after carbonization, respectively. The analysis of fractography images suggests that crack initiation, growth and propagation may occur both at the notch stress concentrator or relatively far from the notch. Possible causes of such response are discussed, namely, (1) residual stresses introduced by processing; (2) shape and size of fillers; and (3) the emanation and accumulation of gases in composites during carbonization.


Asunto(s)
Elastómeros/química , Nanocompuestos/química , Carbono/química , Compuestos Inorgánicos de Carbono/química , Simulación por Computador , Módulo de Elasticidad , Análisis de Elementos Finitos , Dureza , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Nanocompuestos/ultraestructura , Compuestos de Silicona/química , Estrés Mecánico , Resistencia a la Tracción
2.
Mikrochim Acta ; 187(5): 277, 2020 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-32314063

RESUMEN

MXene nanosheets of type Ti3C2Tx were modified with ß-hydroxybutyrate dehydrogenase and then used as a biosensor for amperometric sensing of ß-hydroxybutyrate. The MXene and the nanocomposite were characterized by X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The MXene has a layered structure and proved to be an excellent immobilization matrix providing good compatibility with the enzyme ß-hydroxybutyrate dehydrogenase. The MXene-based biosensor, best operated at a potential of - 0.35 V (vs. Ag/AgCl), displays a wide linear range (0.36 to 17.9 mM), a sensitivity of 0.480 µA mM-1 cm-2, and a low detection limit (45 µM). The biosensor was successfully applied to the determination of ß-hydroxybutyrate in (spiked) real serum samples. Graphical abstract Schematic representation of the synthesis and decoration of Mxene 2D sheets with ß-hydroxybutyrate dehydrogenase for the amperometric determination of ß-hydroxybutyric acid.


Asunto(s)
Ácido 3-Hidroxibutírico/análisis , Compuestos Inorgánicos de Carbono/química , Hidroxibutirato Deshidrogenasa/química , Nanocompuestos/química , Titanio/química , Ácido 3-Hidroxibutírico/metabolismo , Técnicas Biosensibles , Técnicas Electroquímicas , Electrodos , Hidroxibutirato Deshidrogenasa/metabolismo , Tamaño de la Partícula , Propiedades de Superficie
3.
J Vis Exp ; (156)2020 02 16.
Artículo en Inglés | MEDLINE | ID: mdl-32116307

RESUMEN

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal catalysis, the literature on direct heteroarylation is scarce. The presence of heteroatoms such as nitrogen, sulfur and oxygen often make heteroarylation a challenging research field due to catalyst poisoning, product decomposition and the rest. This protocol details a highly efficient direct α-C(sp3) heteroarylation of ketones under microwave irradiation. Key factors for successful heteroarylation include the use of XPhos Palladacycle Gen. 4 Catalyst, excess base to suppress side reactions and the high temperature and pressure achieved in a sealed reaction vial under microwave irradiation. The heteroarylation compounds prepared by this method were fully characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR) and high-resolution mass spectrometry (HRMS). This methodology has several advantages over literature precedents including broad substrate scope, rapid reaction time, greener procedure and operational simplicity by eliminating the preparation of intermediates such as silyl enol ether. Possible applications for this protocol include, but are not limited to, diversity-oriented synthesis for the discovery of biologically active small molecules, domino synthesis for the preparation of natural products and ligand development for new transition metal catalytic systems.


Asunto(s)
Cetonas/síntesis química , Metales/química , Microondas , Elementos de Transición/química , Compuestos Inorgánicos de Carbono/química , Espectroscopía de Resonancia Magnética con Carbono-13 , Catálisis , Cromatografía , Cetonas/química , Paladio/química , Espectroscopía de Protones por Resonancia Magnética , Compuestos de Silicona/química , Temperatura
4.
Environ Sci Pollut Res Int ; 27(2): 1224-1233, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30155638

RESUMEN

In this work, sludge-derived carbon (SC) was innovatively integrated with copper oxide (CuO) on macroporous silicon carbide foams to construct a distinctive catalyst (CuO/SC) with strong catalytic activity, which can effectively activate persulfate (PS) for the removal of methyl mercaptan (CH3SH). The structure and morphology of CuO/SC were investigated by means of XRD, SEM, and EDS. The effects of initial pH values, copper contents, PS dosages, and flow rates on CH3SH removal were also investigated. Under optimal condition, more than 90% of CH3SH was removed by CuO/SC-PS combined system within 10-min reaction due to the synergistic function of CuO and SC. More importantly, on the basis of reactive species trapping and ESR spectroscopy, it is revealed that the responsible reactive species for catalytic CH3SH composition were ·SO4-, ·OH, 1O2, and ·O2- in CuO/SC-PS system. Finally, the possible PS activation scheme of CuO/SC samples was proposed.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Carbono , Cobre/química , Aguas del Alcantarillado , Compuestos de Silicona/química , Especies Reactivas de Oxígeno , Compuestos de Sulfhidrilo/química
5.
Mikrochim Acta ; 186(12): 756, 2019 11 09.
Artículo en Inglés | MEDLINE | ID: mdl-31707552

RESUMEN

Forensic saliva identification represents an increasingly useful auxiliary means of crime investigations, particularly in sex crimes. Salivary bacteria detection techniques have been shown to be viable methods for identifying the presence of saliva. A one-pot method is described for the fabrication of bovine serum albumin-stabilized SiC nanoparticles (SiC@BSA NPs). The SiC@BSA NPs were conjugated to antibacterial peptide GH12 to allow for fluorometric detection and imaging of bacteria in saliva. More specifically, the nanoprobe, with fluorescence excitation/emission maxima at 320/410 nm, was used to detect the oral bacteria S. salivarius levels. The detection limit is 25 cfu·mL-1, and the assay can be performed within 40 min. The nanoprobe was also used to detect bacteria in forensic body fluids including blood, urine, and semen. In all cases, positive results were obtained with (mixed) samples containing saliva, while other saliva samples without saliva showed negative results. Fluorescent images of S. salivarius cells were obtained by implementing a high-content image analysis system. These results suggest that this new nanoprobe can be applied to screen for forensic saliva stains. Graphical abstractSchematic representation of the preparation of SiC@BSA-GH12 nanoprobe for fluorometric detection and imaging of S. salivarius in saliva.


Asunto(s)
Técnicas de Tipificación Bacteriana/métodos , Colorantes Fluorescentes/química , Nanopartículas/química , Saliva/microbiología , Espectrometría de Fluorescencia/métodos , Streptococcus salivarius/aislamiento & purificación , Animales , Compuestos Inorgánicos de Carbono/química , Bovinos , Humanos , Límite de Detección , Oligopéptidos/química , Albúmina Sérica Bovina/química , Compuestos de Silicona/química , Streptococcus salivarius/química
6.
Macromol Rapid Commun ; 40(23): e1900495, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31663644

RESUMEN

Photo-induced thermal polymerization upon near-infrared (NIR) light irradiation has been reported in the literature. In this approach, a component able to convert the NIR light into heat must be used in combination with a thermal initiator to initiate the free-radical polymerization of (meth)acrylates. In recent studies, some absorbers have been presented as very efficient heat generators (called heaters). In the present work, different fillers are investigated as heaters and compared to organic NIR absorbers. An alkoxyamine (e.g., BlocBuilder-MA) is used as thermal initiator and is dissociated by the heat generated by the NIR photoexcitation of the fillers. In the present work, several fillers are examined: graphene oxide, graphene nanoplatelets, multi-walled carbon nanotubes, and silicon carbide. Due to the energy of the photon delivered, NIR light curing is challenging but offers several advantages compared to visible light. The most interesting feature is the deeper penetration of the light inside the photocurable resin, enabling the polymerization of thick samples. Parallel to this, incorporation of fillers in resins allows unique access to composites through photothermal polymerization of (meth)acrylates. Three different wavelengths of irradiation have been studied: 785, 940, and 1064 nm.


Asunto(s)
Rayos Infrarrojos , Temperatura , Compuestos Inorgánicos de Carbono/química , Grafito/química , Ensayo de Materiales , Nanotubos de Carbono/química , Procesos Fotoquímicos , Polimerizacion , Compuestos de Silicona/química
7.
Mikrochim Acta ; 186(9): 660, 2019 08 30.
Artículo en Inglés | MEDLINE | ID: mdl-31471825

RESUMEN

A pyrolytic method is described for preparation of ultrafine Fe3C nanoparticles incorporated into N-doped graphitic carbon nanosheets (Fe3C@NGCSs). Iron phthalocyanine and graphitic carbon nitride (g-C3N4) are used as starting materials. The hybrid nanocomposite was placed on a glassy carbon electrode (GCE) and then applied to simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and xanthine (XA). Figures of merits are as follows: for AA, the linear response range covers the 54.0-5491.0 µM range, the lower detection limit is 16.7 µM, and the best working voltage (vs. the saturated calomel electrode (SCE)) is 0.05 V. The respective data for DA are 1.2-120.8 µM, 0.34 µM and 0.19 V (vs. SCE). For UA, the respective data are 4.8-263.0 µM, 1.4 µM and 0.32 V (vs. SCE), and for XA the data are 4.8-361.0 µM, 1.5 µM and 0.71 V (vs. SCE). The method was successfully applied to their simultaneous determination in spiked serum samples. Graphical abstract Ultrafine Fe3C nanoparticles embedded in N-doped graphitic carbon sheets for simultaneous determination of ascorbic acid, dopamine, uric acid and xanthine.


Asunto(s)
Ácido Ascórbico/análisis , Compuestos Inorgánicos de Carbono/química , Dopamina/análisis , Compuestos de Hierro/química , Nanopartículas/química , Ácido Úrico/análisis , Xantina/análisis , Técnicas Biosensibles , Carbono/química , Técnicas Electroquímicas , Electrodos , Humanos , Tamaño de la Partícula , Propiedades de Superficie
8.
J Mol Graph Model ; 93: 107438, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31521881

RESUMEN

Effective strategies to prevent the electrical tree growth and extend the lifetime of cross-linked polyethylene (XLPE) insulation are of crucial importance for the development of power cable industry. The first-principles study with DFT method was performed to understand the mechanism of aging resistance for SiC/XLPE nanocomposite. The Bader charge redistribution calculations between different types of silicon carbide and XLPE suggest that SiC fillers have the ability of capturing hot electrons to suppress the accumulation of space charges because of their unsaturated electronic structures and magnetism on the Si- or C-terminated surfaces. The interfacial behavior between SiC and XLPE was investigated based on the physical interaction and chemical reactivity. The 3C, 4H and 6H-type SiC with flat Si-terminated surfaces are proposed to be favorable additives by showing relatively strong physical interaction with XLPE to limit its movement, and high activation energy for the hydrogen migration reaction to protect the XLPE.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Polietileno/química , Compuestos de Silicona/química , Electrones , Nanocompuestos/química , Propiedades de Superficie
9.
Nano Lett ; 19(9): 6569-6576, 2019 09 11.
Artículo en Inglés | MEDLINE | ID: mdl-31381357

RESUMEN

Reports reveal that the piezoresistance coefficients of silicon carbide (SiC) nanowires (NWs) are 2 to 4 times smaller than those of their corresponding bulk counterparts. It is a challenge to eliminate contamination in adhering NWs onto substrates. In this study, a new setup was developed, in which NWs were manipulated and fixed by a goat hair and conductive silver epoxy in air, respectively, in the absence of any depositions. The goat hair was not consumed during manipulation of the NWs. The process took advantage of the stiffness and tapered tip of the goat hair, which is unlike the loss issue of beam sources in depositions. With the new fixing method, in situ transmission electron microscopy (TEM) electromechanical coupling measurements were performed on pristine SiC NWs. The piezoresistance coefficient and carrier mobility of SiC NW are -94.78 × 10-11 Pa-1 and 30.05 cm2 V-1 s-1, respectively, which are 82 and 527 times respectively greater than those of SiC NWs reported previously. We, for the first time, report that the piezoresistance coefficient of SiC NW is 17 times those of its bulk counterparts. These findings provide new insights to develop high performance SiC devices and to help avoid catastrophic failure when working in harsh environments.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Cabello/química , Nanocables/química , Compuestos de Silicona/química , Plata/química , Estrés Mecánico , Animales , Cabras , Microscopía Electrónica de Transmisión , Nanocables/ultraestructura
10.
Sci Rep ; 9(1): 11540, 2019 08 08.
Artículo en Inglés | MEDLINE | ID: mdl-31395932

RESUMEN

Silicon has been widely used as a material for microelectronic for more than 60 years, attracting considerable scientific interest as a promising tool for the manufacture of implantable medical devices in the context of neurodegenerative diseases. However, the use of such material involves responsibilities due to its toxicity, and researchers are pushing towards the generation of new classes of composite semiconductors, including the Silicon Carbide (3C-SiC). In the present work, we tested the biocompatibility of Silicon and 3C-SiC using an in vitro model of human neuronal stem cells derived from dental pulp (DP-NSCs) and mouse Olfactory Ensheathing Cells (OECs), a particular glial cell type showing stem cell characteristics. Specifically, we investigated the effects of 3C-SiC on neural cell morphology, viability and mitochondrial membrane potential. Data showed that both DP-NSCs and OECs, cultured on 3C-SiC, did not undergo consistent oxidative stress events and did not exhibit morphological modifications or adverse reactions in mitochondrial membrane potential. Our findings highlight the possibility to use Neural Stem Cells plated on 3C-SiC substrate as clinical tool for lesioned neural areas, paving the way for future perspectives in novel cell therapies for neuro-degenerated patients.


Asunto(s)
Materiales Biocompatibles/química , Células-Madre Neurales/efectos de los fármacos , Neuronas/efectos de los fármacos , Silicio/química , Animales , Materiales Biocompatibles/farmacología , Materiales Biocompatibles/uso terapéutico , Compuestos Inorgánicos de Carbono/química , Compuestos Inorgánicos de Carbono/farmacología , Supervivencia Celular/efectos de los fármacos , Humanos , Ratones , Neuroglía/efectos de los fármacos , Semiconductores , Silicio/farmacología , Silicio/uso terapéutico , Compuestos de Silicona/química , Compuestos de Silicona/farmacología , Propiedades de Superficie
11.
ACS Nano ; 13(10): 11572-11581, 2019 10 22.
Artículo en Inglés | MEDLINE | ID: mdl-31433939

RESUMEN

Implantable electronics are of great interest owing to their capability for real-time and continuous recording of cellular-electrical activity. Nevertheless, as such systems involve direct interfaces with surrounding biofluidic environments, maintaining their long-term sustainable operation, without leakage currents or corrosion, is a daunting challenge. Herein, we present a thin, flexible semiconducting material system that offers attractive attributes in this context. The material consists of crystalline cubic silicon carbide nanomembranes grown on silicon wafers, released and then physically transferred to a final device substrate (e.g., polyimide). The experimental results demonstrate that SiC nanomembranes with thicknesses of 230 nm do not experience the hydrolysis process (i.e., the etching rate is 0 nm/day at 96 °C in phosphate-buffered saline (PBS)). There is no observable water permeability for at least 60 days in PBS at 96 °C and non-Na+ ion diffusion detected at a thickness of 50 nm after being soaked in 1× PBS for 12 days. These properties enable Faradaic interfaces between active electronics and biological tissues, as well as multimodal sensing of temperature, strain, and other properties without the need for additional encapsulating layers. These findings create important opportunities for use of flexible, wide band gap materials as essential components of long-lived neurological and cardiac electrophysiological device interfaces.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Platino (Metal)/química , Compuestos de Silicona/química , Electrónica , Temperatura
12.
ACS Nano ; 13(9): 10002-10014, 2019 09 24.
Artículo en Inglés | MEDLINE | ID: mdl-31433945

RESUMEN

Reactive oxygen species (ROS) are crucial molecules in cancer therapy. Unfortunately, the therapeutic efficiency of ROS is unsatisfactory in clinic, primarily due to their rigorous production conditions. By taking advantage of the intrinsic acidity and overproduction of H2O2 in the tumor environment, we have reported an ROS nanoreactor based on core-shell-structured iron carbide (Fe5C2@Fe3O4) nanoparticles (NPs) through the catalysis of the Fenton reaction. These NPs are able to release ferrous ions in acidic environments to disproportionate H2O2 into •OH radicals, which effectively inhibits the proliferation of tumor cells both in vitro and in vivo. The high magnetization of Fe5C2@Fe3O4 NPs is favorable for both magnetic targeting and T2-weighted magnetic resonance imaging (MRI). Ionization of these NPs simultaneously decreases the T2 signal and enhances the T1 signal in MRI, and this T2/T1 switching process provides the visualization of ferrous ions release and ROS generation for the supervision of tumor curing. These Fe5C2@Fe3O4 NPs show great potential in endogenous environment-excited cancer therapy with high efficiency and tumor specificity and can be guided further by MRI.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Compuestos Férricos/química , Compuestos de Hierro/química , Imagen por Resonancia Magnética , Magnetismo , Nanopartículas/química , Especies Reactivas de Oxígeno/química , Animales , Línea Celular Tumoral , Diagnóstico por Imagen , Femenino , Concentración de Iones de Hidrógeno , Hierro/análisis , Ratones Endogámicos BALB C , Nanopartículas/ultraestructura , Polietilenglicoles/química
13.
Biosens Bioelectron ; 142: 111594, 2019 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-31430612

RESUMEN

We report a novel anode electrocatalyst, iron carbide nanoparticles dispersed in porous graphitized carbon (Nano-Fe3C@PGC), which is synthesized by facile approach involving a direct pyrolysis of ferrous gluconate and a following removal of free iron, but provides microbial fuel cells with superior performances. The physical characterizations confirm the unique configuration of iron carbide nanoparticles with porous graphitized carbon. Electrochemical measurements demonstrate that the as-synthesized Nano-Fe3C@PGC exhibits an outstanding electrocatalytic activity toward the charge transfer between bacteria and anode. Equipped with Nano-Fe3C@PGC, the microbial fuel cells based on a mixed bacterium culture yields a power density of 1856 mW m-2. The resulting excellent performance is attributed to the large electrochemical active area and the high electronic conductivity that porous graphitized carbon provides and the enriched electrochemically active microorganisms and enhanced activity towards the redox reactions in microorganisms by Fe3C nanoparticles.


Asunto(s)
Fuentes de Energía Bioeléctrica , Compuestos Inorgánicos de Carbono/química , Grafito/química , Compuestos de Hierro/química , Nanoestructuras/química , Fuentes de Energía Bioeléctrica/economía , Fuentes de Energía Bioeléctrica/microbiología , Compuestos Inorgánicos de Carbono/economía , Catálisis , Conductividad Eléctrica , Electrodos , Diseño de Equipo , Grafito/economía , Compuestos de Hierro/economía , Nanopartículas/química , Nanopartículas/economía , Nanopartículas/ultraestructura , Nanoestructuras/economía , Nanoestructuras/ultraestructura , Porosidad
14.
J Photochem Photobiol B ; 197: 111515, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31255939

RESUMEN

An extraordinary arrangement of research is as yet going on in the area of orthopedic implants advancement to determine different issues being looked by the engineering today. In spite of a few detriments of the orthopedic metallic inserts, they keep on being utilized, essentially as a result of their unrivaled mechanical properties. We investigated the conceivable utilization of silicon carbide (SiC) as a nano-ceramic covering material of titanium (Ti)-based all out femoral substitution implants. The thought is to keep wear garbage arrangement from the delicate titanium exterior. Silicon carbide is a hard and firmly holding bio-ceramic surface substance, and in light of these physico-chemical properties, it isn't actually degradable, just like the case with apatite (HA). To improve cytocompatibility and osseous-integration, we deposited anodized titanium nanotubes (TiO2) inserts, by electrochemical deposition method (EDM), with silicon carbide (SiC) with apatite (SiC@HA). The deposition was affirmed by SEM, while phase composition properties were assessed by XRD. Calcium affidavit, osteocalcin creation, and articulation of bone genes were essentially higher in rodent osteoblast cell culture on SiC@HA-covered anodized titanium nanotubes than in cells cultured on uncoated anodized titanium nanotubes. Implantation into rodent femurs likewise demonstrated that the SiC@HA-covered substance had unrivaled osseous-integration movement in correlation with that of customary inserts, as evaluated by in vivo tomography and histology. Therefore, anodized titanium nanotubes covered with SiC@HA holds guarantee as an orthopedic implant substance.


Asunto(s)
Regeneración Ósea , Compuestos Inorgánicos de Carbono/química , Materiales Biocompatibles Revestidos/química , Durapatita/química , Nanopartículas/química , Compuestos de Silicona/química , Titanio/química , Animales , Regeneración Ósea/efectos de los fármacos , Huesos/metabolismo , Huesos/patología , Adhesión Celular/efectos de los fármacos , Materiales Biocompatibles Revestidos/farmacología , Materiales Biocompatibles Revestidos/uso terapéutico , Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Fracturas del Fémur/terapia , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Osteoblastos/citología , Osteoblastos/efectos de los fármacos , Osteocalcina/metabolismo , Prótesis e Implantes , Ratas
15.
Anal Chim Acta ; 1073: 30-38, 2019 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-31146833

RESUMEN

Highly N-doped SiC was presented as an optimal electrode for electrochemical immunoassays with a far higher sensitivity than chemiluminescence detection. As the first step, the electrochemical properties of highly N-doped SiC, such as the double-layer capacitance (Cdl), rate constant for electron transfer (kapp) and ideal polarizable potential range (electrochemical window) were analyzed and compared with those of Au, Pt, and graphite electrodes. The highly N-doped SiC electrode was used for the quantification of oxidized 3,3',5,5'-tetramethylbenzidine (TMB) which was widely used as chromogenic substrate for commercialized immunoassay kits. In order to enhance the sensitivity for the quantification of the oxidized TMB the chronoamperometry was applied to avoid the background current of i-V measurement. Finally, the chronoamperometry based on the highly N-doped SiC electrode was applied to commercial immunoassay kits for the medical diagnosis of the human immunodeficiency virus (HIV) and the human hepatitis B surface antigen (hHBsAg). The chronoamperometric measurement based on the highly N-doped SiC electrode was proved to detect at far lower limits in comparison with the conventional optical density measurement as well as the chemiluminescence assay based on luminol as a chemiluminescent probe.


Asunto(s)
Bencidinas/análisis , Técnicas Biosensibles , Compuestos Inorgánicos de Carbono/química , Técnicas Electroquímicas , VIH/aislamiento & purificación , Antígenos de Superficie de la Hepatitis B/aislamiento & purificación , Inmunoensayo , Compuestos de Silicona/química , Electrodos , Humanos
16.
J Hazard Mater ; 378: 120728, 2019 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-31202067

RESUMEN

Enteromorpha prolifera-derived Fe3C/C composite has been fabricated through a facile one-step calcination method. As an advanced Fenton-like catalyst, the obtained Fe3C/C composite displayed high catalytic reactivity to generate hydroxyl radicals. It is worth to note that the removal rate of methylene blue (MB) could effectively reach 100% in a wide pH range (pH = 2˜12) and the maximum degradation capacity of the composite is 660 mg/g. The stability and reusability of Fe3C/C composite catalyst have also been tested, which could remain the removal rate at 100% after 6 consecutive runs. To illustrate the practical application possibility, the Fe3C/C composite catalyst was used for degradation of papermaking and dyeing waste water, which could reduce the COD (chemical oxygen demand) value to less than 50. Additionally, the antibiotic norfloxacin (NOR) could also be catalytically removed by the Fe3C/C composite and the possible removal pathway has also been proposed. The excellent removal performance of Fe3C/C composite for MB and NOR may be attributed to the synergistic effect between porous carbon adsorption and Fe3C catalysis. This study not only provides novel insights into recycling of waste biomass, but also paves a new way for the application of Fe3C/C in dyes and antibiotics waste water treatment areas.


Asunto(s)
Antibacterianos/aislamiento & purificación , Compuestos Inorgánicos de Carbono/química , Catálisis , Colorantes/aislamiento & purificación , Residuos de Medicamentos/aislamiento & purificación , Radical Hidroxilo/química , Compuestos de Hierro/química , Nanocompuestos/química , Oxidantes/química , Ulva/química , Adsorción , Peróxido de Hidrógeno , Residuos Industriales , Hierro , Azul de Metileno , Norfloxacino/aislamiento & purificación , Papel , Eliminación de Residuos Líquidos
17.
Artículo en Inglés | MEDLINE | ID: mdl-30938573

RESUMEN

A study was conducted to characterize the raw wastewater entering a modern cost effective municipal WWTP in Poland using two approaches; 1) a combination of modeling and carbonaceous oxygen demand (COD) fractionation using respirometric test coupled with model estimation (RT-ME) and 2) flocculation/filtration COD fractionation method combined with BOD measurements (FF-BOD). It was observed that the particulate fractions of COD obtained using FF-BOD method was higher than those estimated by RT-ME approach. Contrary to the above, the values of inert soluble fraction evaluated by FF-BOD method was significantly lower than RT-ME approach (2.4% and 3.9% respectively). Furthermore, the values for low colloidal and particulate fractions as well as soluble inert fractions were different than expected from a typical municipal wastewater. These observations suggest that even at low load (10% of the total wastewater treatment inflow), the industrial wastewater composition can significantly affect the characteristics of municipal wastewater which could also affect the performance and accuracy of respirometric tests. Therefore, in such cases, comparison of the respirometric tests with flocculation/filtration COD/BOD measurements are recommended. Oxygen uptake rate profile with settled wastewater and/or after coagulation-flocculation, however, could still be recommended as a "rapid" control method for monitoring/optimising modern cost-effective wastewater treatment plants.


Asunto(s)
Análisis de la Demanda Biológica de Oxígeno , Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos/economía , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Análisis de la Demanda Biológica de Oxígeno/métodos , Análisis de la Demanda Biológica de Oxígeno/normas , Calibración , Compuestos Inorgánicos de Carbono/química , Fraccionamiento Químico/métodos , Ciudades , Análisis Costo-Beneficio , Monitoreo del Ambiente/métodos , Monitoreo del Ambiente/normas , Filtración , Floculación , Humanos , Oxígeno/química , Polonia , Purificación del Agua/economía , Purificación del Agua/métodos , Purificación del Agua/normas
18.
ACS Nano ; 13(3): 2870-2878, 2019 03 26.
Artículo en Inglés | MEDLINE | ID: mdl-30822381

RESUMEN

Magnetic nanoparticles are important tools for biomedicine, where they serve as versatile multifunctional instruments for a wide range of applications. Among these applications, magnetic hyperthermia is of special interest for the destruction of tumors and triggering of drug delivery. However, many applications of magnetic nanoparticles require high-quality magnetic nanoparticles displaying high specific absorption rates (SARs), which remains a challenge today. We report here the functionalization and stabilization in aqueous media of highly magnetic 15 nm iron carbide nanoparticles featuring excellent heating power through magnetic induction. The challenge of achieving water solubility and colloidal stability was addressed by designing and using specific dopamine-based ligands. The resulting nanoparticles were completely stable for several months in water, phosphate, phosphate-buffered saline, and serum-containing media. Iron carbide nanoparticles displayed high SARs in water and viscous media (water/glycerol mixtures), even after extended exposition to water and oxygen (SAR up to 1000 W·g-1 in water at 100 kHz, 47 mT). The cytotoxicity and cellular uptake of iron carbide nanoparticles could be easily tuned and were highly dependent on the chemical structure of the ligands used.


Asunto(s)
Materiales Biocompatibles/química , Compuestos Inorgánicos de Carbono/química , Compuestos de Hierro/química , Nanopartículas de Magnetita/química , Agua/química , Materiales Biocompatibles/síntesis química , Compuestos Inorgánicos de Carbono/síntesis química , Dopamina/síntesis química , Dopamina/química , Glicerol/química , Células HeLa , Humanos , Compuestos de Hierro/síntesis química , Ligandos , Estructura Molecular , Oxígeno/química
19.
IEEE Trans Biomed Eng ; 66(12): 3526-3533, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-30908188

RESUMEN

Nanosecond electroporation of cell organelles is being studied since more than a decade, but it is still not entirely understood. Unique prototype hardware equipment and challenging measuring methods may also be a contributing reason for this situation. In the scope of this paper, we improve the performance of the high-voltage nanosecond pulse generator by introducing silicon carbide (SiC) mosfets. We developed a new high-voltage diode opening switch (DOS)-nanosecond pulse generator for laboratory use for in vitro experiments in electroporation cuvettes. Analysis and comparison of the most commonly used switching technologies in pulse generators were made. The device is designed by two parallel two-stage Marx-bank circuits with SiC mosfets that generates up to 200 A in the resonant network. A driving circuit for stable simultaneous switching of SiC mosfets was developed. The developed generator can deliver from 500 V to more than 6 kV, approximately 8 ns pulses to a 50 Ω load. Even though the amplitude of the output pulse is not as high as expected, the multiplication factor [Formula: see text] is still approximately 9, which is an improvement compared to the previously published linear DOS generator. Measurement and evaluation process is described in detail. Additionally, we emphasize on the size of an error that occurs during measurements.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Electroporación/instrumentación , Nanotecnología/instrumentación , Semiconductores , Compuestos de Silicona/química , Diseño de Equipo
20.
J Hazard Mater ; 369: 621-631, 2019 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-30825808

RESUMEN

The efficiency of zero-valent iron (Fe0) for the degradation of contaminants in water or soil can be highly reduced by side reactions with oxygen or water. This work was conducted to test whether this drawback can be effectively suppressed by the carbonation of Fe0 with pyrolyzed biomass, which forms a Fe3C composite. The composite Fe3C was characterized and its reactivity and stability were assessed in batch tests with methyl orange (MO) as a model pollutant. The results indicated that the removal rate of MO on Fe3C composite was higher than that of Fe0 (7.587 mg/(g·min) vs. 4.306 mg/(g·min)) at pH 4, where the degradation mechanism was confirmed by high-performance liquid chromatography-mass spectrometry. More importantly, the produced iron oxide in the Fe3C composite was highly suppressed. Regeneration studies showed that after three times of cycling, the removal efficiency of MO on Fe3C composite was kept to 99.42%, but Fe0 almost lost its reactivity. In situ chemical reduction of a colorimetric redox probe (indigo-5, 5'-disulfonate, I2S) quantitatively demonstrated that Fe3C composite has the reduction kinetics of I2S obviously slower than Fe0, indicating that Fe3C composite improved the stability of incorporated Fe0 to resist the side oxidation.


Asunto(s)
Biomasa , Compuestos Inorgánicos de Carbono/química , Colorantes/aislamiento & purificación , Compuestos de Hierro/química , Adsorción , Compuestos Azo , Colorimetría , Compuestos Férricos/química , Concentración de Iones de Hidrógeno , Cinética , Contaminantes Químicos del Agua/aislamiento & purificación
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...