Urease enzyme was covalently attached on the poly(glycidylmethacrylate) (PGMA)-grafted iron oxide nanoparticles on Au electrode for the fabrication of urea biosensor. The telomere of poly(glycidylmethacrylate) (PGMA) with a trimethoxysilyl terminal group was synthesized by telomerization of glycidylmethacrylate. Iron oxide nanoparticles were coated with telomere of poly(glycidylmethacrylate) in order to obtain good enzyme immobilization platform. The telomere and nanoparticles were characterized by using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). The biosensor’s potentiometric response was measured as a function of urea concentration in phosphate buffer solution (10 mM, pH 7.5) and showed a linear range of 0.25–5.0 mM urea. The produced biosensor exhibited a good response time of ~8 s and was stable for about two months. The basic features (optimum pH, optimum temperature, interference and storage stability) of the enzyme electrode were determined. 相似文献
Summary. The first polymeric halotrioxochromate, dipyrazinium tri(fluorotrioxochromate), was prepared and used for quantitative oxidation
of several organic substrates. This novel compound is more efficient than, and has certain advantages over, its monomeric
analogues in terms of the amount of oxidant required, reaction times, and yields. 相似文献
In 1999 investigation, the needles of Sabina chinesis L. from 11 hot spot tourist cities extending over China were collected as biomonitors for evaluation of atmospheric elemental differences in those cities. Thirty five elements were determined by instrumental neutron activation analysis (INAA). The experimental data reflected the environmental alteration in the cities that have different geographical position, population burden and industrialized level. Eventually by using the data processed by factor analysis (FA) and subsequent cluster analysis (CA), the cities were grouped into six sorts of the urban atmospheric deposition with corresponding elements. 相似文献
In this paper, we introduce real lightlike hypersurfaces of indefinite
quaternion Kaehler manifold. Fundamental properties of real lightlike
hypersurfaces of an indefinite quaternion Kaehler manifold are
investigated. We prove the non existence of real lightlike hypersurfaces
in indefinite qaternionic space form under some conditions.
Received 31 October 2000; revised 20 June 2001. 相似文献
In the title compound, C16H20Cl2O8, the bicyclic system contains a central non‐planar cyclohexane ring which is fused to a cyclobutane moiety. The cyclohexane ring has a chair conformation and the whole system adopts a syn conformation. The structure provides information on the stereochemical course of the chlorination, photo‐oxidation and hydroxylation steps of the reaction. 相似文献
We have developed a new immunological biosensor for ultrasensitive quantification of human epidermal growth factor receptor-3(HER-3). In order to construct the biosensor, the gold electrode surface was layered with, hexanedithiol, gold nanoparticles, and cysteamine, respectively. Anti-HER-3 antibody was covalently attached to cysteamine by glutaraldehyde and used as a bioreceptor in a biosensor system for the first time by this study. Surface characterization was obtained by means of electrochemical impedance spectroscopy and voltammetry. The proposed biosensor showed a good analytical performance for the detection of HER-3 ranging from 0.2 to 1.4 pg mL−1. Kramers–Kronig transform was performed on the experimental impedance data. Moreover, in an immunosensor system, the single frequency impedance technique was firstly used for characterization of interaction between HER-3 and anti-HER-3. Finally the presented biosensor was applied to artificial serum samples spiked with HER-3. 相似文献
In this work, we report optomechanical coupling, resolved sidebands and phonon lasing in a solid‐core microbottle resonator fabricated on a single mode optical fiber. Mechanical modes with quality factors (Qm) as high as 1.57 × 104 and 1.45 × 104 were observed, respectively, at the mechanical frequencies and . The maximum Hz is close to the theoretical lower bound of 6 × 1012 Hz needed to overcome thermal decoherence for resolved‐sideband cooling of mechanical motion at room temperature, suggesting microbottle resonators as a possible platform for this endeavor. In addition to optomechanical effects, scatter‐induced mode splitting and ringing phenomena, which are typical for high‐quality optical resonances, were also observed in a microbottle resonator.
A cellulose–graphite oxide composite was synthesized and characterized as an adsorbent for dispersive solid-phase extraction of rhodium from various samples before atomic absorption detection. The pH, adsorbent volume, centrifugation time and rate, eluent concentration, volume and type, adsorption and elution contact time, sample volume, and matrix interferences were optimized. The developed method is simple, rapid, and inexpensive. The tolerance limits for rhodium were 10,000?mg?L?1 sodium, 25,000?mg?L?1 potassium, 10,000?mg?L?1 magnesium, and 20,000?mg?L?1 calcium. The recovery for rhodium exceeded 95%. Elution was performed with 10?mL of 2.5?mol?L?1 H2SO4. The adsorption and elution contact times were 30 and 60?s, respectively. The detection limit of the method for rhodium was 5.4?µg?L?1 and the precision as the relative standard deviation was 1.6%. A certified reference material 2556 (used auto catalyst pellets) and fortified samples were analyzed to evaluate the accuracy of the method. The optimized method was used for the preconcentration of rhodium from tap water, well water, wastewater, seawater, catalytic converters, and street dust. 相似文献
This study details the metal and metalloid accumulation profiles of three species of sea cucumbers (Holothuriamammata, Holothuriapolii and Holothuriatubulosa) native to Alia?a and Ild?r (?zmir, Turkey), two regions that are representative of industrial and residential districts, respectively. A total of 11 elements were analysed (Fe, Cu, Mn, Zn, Cr, Co, V, Ni, Cd, Pb and As) from gut and body wall tissues of holothurians and in sediment samples. The Mann–Whitney U analysis revealed statistical difference between locations and tissues. Accumulations of Alia?a samples were significantly higher than Ild?r samples with respect to Zn, V, Mn, Cr, Fe and Co while accumulations were significantly higher in the gut than body wall regardless of the region for all elements tested. The correlation analysis showed more and stronger correlations in the gut than in the body wall. In addition, metal(loid) concentrations in the sediment were found to correlate strongly with these in the sea cucumber gut. The cluster analysis displayed totally different element accumulation pattern for Alia?a and Ild?r in the both tissues which indicate that anthropogenic effects start to alter the bioaccumulation of metal(loids). Biota-sediment accumulation factors (BSAF) and metal contamination index were calculated to determine the extent of metal(loid) uptake and to compare total elemental accumulation at each region. Gut tissue elemental BSAF is higher than body wall for all elements at both areas. Cd has the highest value with 5.582 (gut tissue) and the lowest are Ni, V and Cr with 0.001 (body wall tissue). In addition, sediment results were compared with previous studies and sediment quality guidelines and found to exceed the lowest effect level (LEL) values for As and Ni. 相似文献
The structure of the title compound C11H7FN2O2S was characterized by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/n with Z = 12, i.e. with three molecules in asymmetric unit. The molecules are not planar: the dihedral angles between the planes of thiophene and the benzene rings are 42.3(3)°, 42.0(3)°, and 48.9(2)°. In the crystal, intermolecular C–H···F interactions link the molecules through R22 (14) ring motif. The crystal packing is also stabilized by π···π interactions. 相似文献