共查询到20条相似文献,搜索用时 15 毫秒
1.
The direct electrochemistry of morphine on modified multiwall carbon nanotubes using carbon ionic liquid (i.e., 1-butyl-3-methylimidazolium
hexafluoro phosphate, ([C4mim]–[PF6])) was studied. It was found that the electrode showed sensitive voltammetric response
to morphine. The experimental results suggested that the modified electrode promoted electron transfer reaction for the oxidation
of morphine. The electron transfer coefficient and charge transfer resistant (R
ct) of morphine at the modified electrode were calculated. Under the optimized conditions at pH 8.0, the peak current was linear
to morphine concentrations over the concentration range of 0.45–450 μmol L−1, using differential pulse voltammetry. The detection limit was 0.14 μmol L−1. The proposed method was successfully applied to the determination of morphine in both ampoules and urine samples. 相似文献
2.
Amorphous ErSiO films have been fabricated on p-type Si (001) substrates using rf magnetron sputtering technique. X-ray diffraction,
high-resolution transmission electron microscopy, and atomic force microscopy were employed to investigate the samples. It
is found that ErSiO film exhibits a flat surface, a sharp interface and superior electrical properties after post-deposition
annealing in O2 ambience for 30 min at 450°C. The effective dielectric constant of the film is measured to be 14.2, and the effective oxide
thickness reaches 1.9 nm, with a low leakage current density of 1.1×10−4 A/cm2 at an electric field of 1 MV cm−1 after annealing at 450°C. The obtained characteristics make the amorphous ErSiO films a promising substitute for SiO2 as a high-k gate dielectric. 相似文献
3.
The manganese oxide/multi-walled carbon nanotube (MnO2/MWNT) composite and the manganese oxide/acetylene black (MnO2/AB) composite were prepared by translating potassium permanganate into MnO2 which formed the above composite with residual carbon material using the redox deposition method and carbon as a reducer.
The products were characterized by X-ray diffraction, Fourier transform infrared, and scanning electron microscope. Electrochemical
properties of both the MnO2/MWNT and MnO2/AB electrodes were studied by using cyclic voltammetry, electrochemical impedance measurement, and galvanostatic charge/discharge
tests. The results show that the MnO2/MWNT electrode has better electrochemical capacitance performance than the MnO2/AB electrode. The charge–discharge test showed the specific capacitance of 182.3 F·g−1 for the MnO2/MWNT electrode, and the specific capacitance of 127.2 F·g−1 for the MnO2/AB electrode had obtained, within potential range of 0–1 V at a charge/discharge current density of 200 mA·g−1 in 0.5 mol·L−1 potassium sulfate electrolyte solution in the first cycle. The specific capacitance of both the MnO2/MWNT and MnO2/AB electrodes were 141.2 F·g−1 and 78.5 F·g−1 after 1,200 cycles, respectively. The MnO2/MWNT electrode has better cycling performance. The effect of different morphologies was investigated for both MnO2/MWNT and MnO2/AB composites. 相似文献
4.
Azab HA Duerkop A Mogahed EM Awad FK Abd El Aal RM Kamel RM 《Journal of fluorescence》2012,22(2):659-676
This work describes the application of time resolved fluorescence in microtiterplates and electrochemical methods on glassy
carbon electrode for investigating the interactions of europium-3-carboxycoumarin with pesticides aldicarb, methomyl and prometryne.
Stern-volmer studies at different temperatures indicate that static quenching dominates for methomyl, aldicarb and prometryne.
By using Lineweaver-Burk equation binding constants were determined at 303 K, 308 K and 313 K. A thermodynamic analysis showed
that the reaction is spontaneous with ΔG being negative. The enthalpy ΔH and the entropy ΔS of reactions were all determined.
A time-resolved (gated) luminescence-based method for determination of pesticides in microtiterplate format using the long-lived
europium-3-carboxycoumarin has been developed. The limit of detection is 4.80, 5.06 and 8.01 μmol L−1 for methomyl, prometryne and aldicarb, respectively. This is the lowest limit of detection achieved so far for luminescent
lanthanide-based probes for pesticides. The interaction of the probe with the pesticides has been investigated using cyclic
voltammetry (CV), differential pulse polarography (DPP), square wave voltammetry (SWV) and linear sweep voltammetry (LSV)
on a glassy carbon electrode in I = 0.1 mol L−1 p-toluenesulfonate at 25 °C. The diffusion coefficients of the reduced species are calculated. The main properties of the
electrode reaction occurring in a finite diffusion space are the quasireversible maximum and the splitting of the net SWV
peak for Eu(III) ions in the ternary complex formed . It was observed that the increase of the cathodic peak currents using
LSV is linear with the increase of pesticides concentration in the range 5 × 10−7 to 1 × 10−5 mol L−1. The detection limit (DL) were about 1.01, 2.23 and 1.89 μmolL−1 for aldicarb, methomyl and prometryne, respectively. In order to assess the analytical applicability of the method, the influence
of various potentially interfering species was examined. Influence of interfering species on the recovery of 10 μmol L−1 pesticides has been investigated. 相似文献
5.
Feoktistov N. A. Sakharov V. I. Serenkov I. T. Tolmachev V. A. Korkin I. V. Aleksenskii A. E. Vul’ A. Ya. Golubev V. G. 《Technical Physics》2011,56(5):718-724
The aerosol deposition of detonation nanodiamonds (DNDs) on a silicon substrate is comprehensively studied, and the possibility
of subsequent growth of nanocrystalline diamond films and isolated particles on substrates coated with DNDs is demonstrated.
It is shown that a change in the deposition time and the weight concentration of DNDs in a suspension in the range 0.001–1%
results in a change in the shape of DND agglomerates and their number per unit substrate surface area N
s
from 108 to 1011 cm−2. Submicron isolated diamond particles are grown on a substrate coated with DND agglomerates at N
s
≈ 108 cm−2 using microwave plasma-enhanced chemical vapor deposition. At N
s
≈ 1010 cm−2, thin (∼100 nm) nanodiamond films with a root-mean-square surface roughness less than 15 nm are grown. 相似文献
6.
Chien-Chon Chen Jin-Shyong Lin Eric Wei-Guang Diau Tzeng-Feng Liu 《Applied Physics A: Materials Science & Processing》2008,92(3):615-620
Self-cleaning of a surface of nanotube arrays of anodic titanium oxide (ATO) is demonstrated. The ATO was prepared in fluoride
ion containing sulfate electrolytes with a structure of 0.4 μm length, 100 nm pores diameter, 120 nm interpore distance, 25 nm
pore wall thickness, a 8×109 pores cm−2 pore density, and 68.2% porosity. Prepared as thin films either directly from a Ti foil or on a glass substrate, these arrays
have the property that water drops spread quickly over the surface of the films without irradiation. In contrast, a flat anatase
TiO2 film requires irradiation with UV light for several minutes before the contact angle decreases to zero. The observed self-cleaning
behavior of the ATO thin films is due to the capillary effect of the nanochannel structure and the superhydrophilic property
of the anatase TiO2 surface inside the tube. 相似文献
7.
Zakutayev A. Newhouse P. F. Kykyneshi R. Hersh P. A. Keszler D. A. Tate J. 《Applied Physics A: Materials Science & Processing》2011,102(2):485-492
Undoped and 10% Ca-doped BiCuOSe thin films are prepared by pulsed laser deposition without ex-situ processing. The influence
of the preparation conditions on structure and properties of Bi0.9Ca0.1CuOSe thin films on amorphous silica substrates is studied. The highest achieved concentration and mobility of free holes
(3.9×1020 cm−3 and 3.5 cm2/Vs) was close to that measured in strongly c-axis oriented samples on SrTiO3 substrates (4.0×1020 cm−3 and 7.5 cm2/Vs). The Bi0.9Ca0.1CuOSe films on SrTiO3 show almost temperature-independent Seebeck coefficient and their resistivity increases with increasing temperature. The
Seebeck coefficient of undoped BiCuOSe films on SrTiO3 increases below 150°K, and the resistivity shows a flat plateau centered at this temperature. Optical measurements suggest
that BiCuOSe has an indirect bandgap of 0.8 eV and a strong absorption edge at 1.45 eV. Ab-initio calculations of the electronic
band structure, effective masses and optical properties of BiCuOSe are also presented. 相似文献
8.
E. Coetsee J. J. Terblans H. C. Swart 《Applied Physics A: Materials Science & Processing》2010,101(4):645-650
Y2SiO5:Ce phosphor thin films were grown onto Si(100) substrates with pulsed laser deposition (PLD) using a 248-nm KrF excimer laser.
Process parameters were varied during the growth process and the effect on the surface morphology and cathodoluminescence
(CL) was analysed. The process parameters that were changed included the following: gas pressure (vacuum (5×10−6 Torr), 1×1−2 Torr and 1 Torr O2), different gas species (O2, Ar and N2 at a pressure of 455 mTorr), laser fluence (1.6±0.1 J cm−2 and 3.0±0.3 J cm−2) and substrate temperature (400 and 600°C). The surface morphology was investigated with atomic force microscopy (AFM). The
morphology of the thin films ablated in vacuum and 10 mTorr ambient O2 showed more or less the same trend. An increase in the pressure to 1 Torr O2, however, showed a definite increase in deposited particle sizes. Ablation in N2 gas resulted in small particles of 20 nm in diameter and ablation in O2 gas produced bigger particles of 20, 30 and 40 nm as well as an agglomeration of these particles into bigger size clusters
of 80 to 100 nm. Ablation in Ar gas led to particle sizes of 30 nm and the particles were much more spherically defined and
evenly distributed on the surface. The higher fluence deposition led to bigger particle and grain sizes as well as thicker
layers with respect to the lower fluence. The particle sizes of the higher fluence vary mainly between 130 and 140 nm and
the lower fluence sizes vary between 50 and 60 nm. The higher fluence particles consist of smaller particles ranging from
5 to 30 nm as measured with AFM. The surface structure of the thin film ablated at 400°C substrate temperature is less compact
(lesser agglomeration of particles than at 600°C). The increase in substrate temperature definitely resulted in a rougher
surface layer. CL was measured to investigate the effect of the surface morphology on the luminescent intensities. The increased
O2 ambient (1 Torr) resulted in a higher CL intensity compared to the thin films ablated in vacuum. The thin film ablated in
Ar gas showed a much higher CL intensity than the other thin films. Ablation at a high fluence resulted in a higher CL intensity.
The higher substrate temperature resulted in better CL intensities. The more spherically shaped particles and rougher surface
led to increase CL intensities. 相似文献
9.
In the paper, a chemiluminescence (CL) system was developed based on the catalytical effect of diperiodatocuprate (III) (DPC)
on the 1,10-phenanthroline (phen)/hydrogen peroxide (H2O2) in the presence of cetyltrimethylammonium bromide (CTAB). The effects of experimental conditions were investigated. Meanwhile
the increase of CL intensity of the DPC/phen/H2O2/CTAB system is proportional to the concentration of phen in the range of low concentration. The linear range of the calibration
curve is 5.0 × 10−9–1.0 × 10−6 mol L−1, and the corresponding detection limit is 1.9 × 10−9 mol L−1. The effects of phenolic compounds (PCs) on the system were investigated. Hydroquinone was used as an example to investigate
the application of the CL system to the determination of PCs. The quenched CL intensity is linearly related to the logarithm
of concentration of hydroquinone. The linear range of the calibration curve is 2.5 × 10−9–1.0 × 10−5 g mL−1, and the corresponding detection limit is 1.8 × 10−9 g mL−1. This phen and hydroquinone can be synchronously determined. The method was applied to the determination of hydroquinone
in water samples and the recoveries were from 92% to 106%. 相似文献
10.
The efficiency of excited-state interaction between Tb3+ and the industrial product Cilostazol (CIL) has been studied in different solvents. High luminescence intensity peak at 545 nm
of terbium complex in acetonitrile was obtained. The photophysical properties of the green emissive Tb3+ complex have been elucidated, the terbium was used as optical sensor for the assessment of CIL in the pharmaceutical tablets
and body fluids at pH 3.1 and λex = 320 nm with a concentration range 1.0 × 10−9–1.0 × 10−6 mol L−1 of CIL, correlation coefficient of 0.998 and detection limit of 7.5 × 10−10 mol L−1. 相似文献
11.
H. Hoffmann J. Pickl M. Schmidt D. Krause 《Applied Physics A: Materials Science & Processing》1978,16(3):239-246
Indium oxide films doped with tin (ITO-films) have been hf-sputtered from an 80 at-%In2O3/20 at-%SnO2 target onto glass substrates. The sputter atmosphere contained mainly argon (10−2Torr) with addition of oxygen (0≦p
O
2≦2·10−2Torr). The sputtered films aren-conductors. The conductivity and density of charge carriers depend on the oxygen content of the sputter gas. They could be
varied by two orders of magnitude. In air or in oxygen atmosphere the films oxidize at the surface and for a certain depth
beneath the surface, thus decreasing the conductivity. The Hall mobility of the sputtered films is smaller (≈10 cm2V−1 s−1) than one observes at ITO films produced by CVD sparaying or other methods. The conductivity of as sputtered films approached
maximum values of about 1000Ώ−1cm−1. 相似文献
12.
Electrochemical preparation of nanosized manganese dioxides from manganese chloride solutions 总被引:1,自引:0,他引:1
Manganese dioxides were fabricated by electrodeposition from MnCl2, MgCl2/MnCl2, and HCl/MnCl2 aqueous solutions at 100 °C, respectively. Oxidation behaviors of Mn(II) on titanium plate were studied by cyclic voltammetry.
X-ray diffractometer, scanning electron microscopy, and BET measurements were used to characterize manganese dioxide crystal
structures, micromorphologies, and specific surface area. The effects of electrolyte composition and potential on manganese
dioxide crystal structure and micromorphology were investigated. Manganese dioxide structure type and micromorphology were
controlled by adjusting electrolyte composition. γ-MnO2 aggregates consisting of nanosheets were electrodeposited from 0.05 mol L−1 MnCl2 aqueous solution. Crystallinity and the size of γ-MnO2 nanosheet were increased by adding Mg(II) into electrolyte. Nanosized rod-like α-MnO2 with higher specific surface area was prepared by adding 2.0 mol L−1 hydrochloric acid into manganese chloride solution. 相似文献
13.
H. Kim A. Cepler C. Cetina D. Knies M. S. Osofsky R. C. Y. Auyeung A. Piqué 《Applied Physics A: Materials Science & Processing》2008,93(3):593-598
Present p-type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state
within days after deposition. One approach to grow higher quality p-type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization
of Zr–N codoped p-type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N
codoped p-type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N2O background pressures between 10−5 to 10−2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N2O deposition pressure. P-type conduction was observed for films grown at pressures between 10−3 to 10−2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10−3 Torr of N2O show p-type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×1018 cm−3, and a Hall mobility of 1.4 cm2 V−1 s−1. The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films. 相似文献
14.
The specific heat of undercooled liquid Ni80Fe10Cu10 alloy was experimentally measured by electromagnetic levitation drop calorimeter, and also numerically simulated by the molecular
dynamics method. The achieved maximum undercooling is up to 252 K (0.15 T
L) in the experiments, and the measured result is 41.67 J mol−1 K−1. The simulation provides calculated data within 0∼702 K undercooling range, which is much broader than the experimental regime.
The simulated value is 37.02 J mol−1 K−1. Although there exists a difference of 4.65 J mol−1 K−1 between them, the result is quite acceptable for simulation. Furthermore, the liquid structure of undercooled Ni80Fe10Cu10 alloy is studied in terms of the total and partial pair distribution functions, which display that the ordered degree of
atoms enhances from a normal liquid to metastable state. 相似文献
15.
Water-soluble Mn2+-doped ZnS quantum dots (QDs) were prepared using mercaptoacetic acid as the stabilizer. The optical properties and structure
features were characterized by X-Ray, absorption spectrum, IR spectrum and fluorescence spectrum. In pH 7.8 Tris-HCl buffer,
the QDs emitted strong fluorescence peaked at 590 nm with excitation wavelength at 300 nm. The presence of sulfide anion resulted
in the quenching of fluorescence and the intensity decrease was proportional to the S2− concentration. The linear range was from 2.5 × 10−6 to 3.8 × 10−5 mol L−1 with detection limit as 1.5 × 10−7 mol L−1. Most anions such as F−, Cl−, Br−, I−, CH3CO2
−, ClO4
−, CO3
2−, NO2
−, NO3
−, S2O3
2−, SO3
2− and SO4
2− did not interfere with the determination. Thus a highly selective assay was proposed and applied to the determination of
S2− in discharged water with the recovery of ca. 103%. 相似文献
16.
The present work reports on the synthesis, characterization and performance of a new metal-containing ionic liquid [(C3H7)2-bim]2[CdCl4] (bim = benzimidazole) as an electrocatalyst for trichloroacetic acid (TCA) and bromate reduction. The structure of Cd(II)-containing
ionic liquid (Cd-IL) was characterized by X-ray crystallography, IR spectroscopy, and elemental analysis. The molecular structure
contains two independent cations of 1,3-dipropyl-benzimidazolium and one anion of CdCl42−. The cadmium atom has a tetrahedral geometry by coordinating to four chlorine atoms. The melting point of Cd-IL is 73 °C.
Electrochemical properties of the Cd-IL have been investigated by preparing bulk-modified carbon paste electrode, and Cd-IL
is used as a binder and an electrocatalyst. This modified electrode has good electrocatalytic activity toward reduction of
TCA and bromate. The detection limit and the sensitivity are 0.01 μM and 102.72 μA μM−1 for trichloroacetic acid detection and 0.003 μM and 496.15 μA μM−1 for bromate detection. This work demonstrates that the Cd-IL may become a new kind of functional material in constructing
chemicals and biosensors. 相似文献
17.
Chan y Díaz E. Duarte-Moller A. Camacho Juan M. Castro-Rodríguez R. 《Applied Physics A: Materials Science & Processing》2012,106(3):619-624
SnO2 thin films have been deposited on glass substrates by pulsed Nd:YAG laser at different oxygen pressures, and the effects
of oxygen pressure on the physical properties of SnO2 films have been investigated. The films were deposited at substrate temperature of 500°C in oxygen partial pressure between
5.0 and 125 mTorr. The thin films deposited between 5.0 to 50 mTorr showed evidence of diffraction peaks, but increasing the
oxygen pressure up to 100 mTorr, three diffraction peaks (110), (101) and (211) were observed containing the SnO2 tetragonal structure. The electrical resistivity was very sensitive to the oxygen pressure. At 100 mTorr the films showed
electrical resistivity of 4×10−2 Ω cm, free carrier density of 1.03×1019 cm−3, mobility of 10.26 cm2 V−1 s−1 with average visible transmittance of ∼87%, and optical band gap of 3.6 eV. 相似文献
18.
Vasily Lavrentiev Jiri Vacik Hiroshi Naramoto Kazumasa Narumi 《Applied Physics A: Materials Science & Processing》2009,95(3):867-873
The structure transformation occurring in fullerene film under bombardment by 50 keV C60+ cluster ions is reported. The Raman spectra of the irradiated C60 films reveal a new peak rising at 1458 cm−1 with an increase in the ion fluence. This feature of the Raman spectra suggests linear polymerization of solid C60 induced by the cluster ion impacts. The aligned C60 polymeric chains composing about 5–10 fullerene molecules have been distinguished on the film surface after the high-fluence
irradiation using atomic force microscopy (AFM). The surface profiling analysis of the irradiated films has revealed pronounced
sputtering during the treatment. The obtained results indicate that the C60 polymerization occurs in a deep layer situated more than 40 nm below the film surface. The deep location of the C60 polymeric phase indirectly confirms the dominant role of shock waves in the detected C60 phase transformation. 相似文献
19.
Attia MS Mahmoud WH Ramsis MN Khalil LH Othman AM Hashem SG Mostafa MS 《Journal of fluorescence》2011,21(4):1739-1748
A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical
tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably
enhance the luminescence intensity of the Sm3+ ion in Sm3+- DC complex at λex = 400 nm. The produced luminescence intensity of Sm3+- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic
range for the determination of DC is 1 × 10−8 – 5 × 10−6 mol L−1 and in case of quantum yield calculations is 7 × 10−9 – 5 × 10−6 mol L−1 with detection limit of 6.5 × 10−10 mol L−1. The enhancement mechanism of the luminescence intensity in the Sm3+- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which
Eu3+ ion is used instead of Sm3+ ion is also studied. 相似文献
20.
Youssef AO 《Journal of fluorescence》2012,22(3):827-834
A new, simple, sensitive and selective spectrofluorimetric method for the determination of Hydrochlorothiazide was developed
in acetonitrile at pH 6.2. The Hydrochlorothiazide can remarkably enhance the luminescence intensity of the Tb3+ ion doped in sol–gel matrix at λex = 370 nm. The intensity of the emission band of Tb3+ ion doped in sol–gel matrix was increased due to the energy transfer from the triplet excited state of Hydrochlorothiazide
to (5D4) excited energy state of Tb3 ion. The enhancement of the emission band of Tb3+ ion doped in sol–gel matrix at (5D4→7 F5) 545 nm was directly proportion to the concentration of Hydrochlorothiazide with a dynamic ranges of 5.0 × 10−10—5.0 × 10−6 mol L−1 and detection limit of 2.2 × 10−11 mol L−1. 相似文献