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1.
Uniform particles of manganese compounds obtained by forced hydrolysis of manganese(II) acetate 总被引:1,自引:0,他引:1
M. Ocaña 《Colloid and polymer science》2000,278(5):443-449
Procedures for the preparation at low temperature (80 °C) of uniform colloids consisting of Mn3O4 nanoparticles (about 20 nm) or elongated α-MnOOH particles with length less than 2 μm and width 0.4 μm or less, based on
the forced hydrolysis of aqueous manganese(II) acetate solutions in the absence (Mn3O4) or the presence (α-MnOOH) of HCl are described. These solids are only produced under a very restrictive range of reagent
concentrations involving solutions of 0.2–0.4 mol dm−3 manganese(II) acetate for Mn3O4 and of 1.6–2 mol dm−3 Mn(II) and 0.2–0.3 mol dm−3 HCl for α-MnOOH. The role that the acetate anions play in the precipitation of these solids is analyzed. It seems that these
anions promote the oxidation of Mn(II) to Mn(III), which readily hydrolyze causing precipitation. The evolution of the characteristics
of the powders with temperature up to 900 °C is also reported. Thus, Mn3O4 particles transform to Mn2O3 upon calcination at 800 °C; this is accompained by a sintering process. The α-MnOOH sample also experiences several phase
transformations on heating. First, it is oxidized at low temperatures (250–450 °C) giving MnO2 (pyrolusite), which is further reduced to Mn2O3 at 800 °C. After this process the particles still retain their elongated shape.
Received: 19 October 1999 Accepted: 24 November 1999 相似文献
2.
Summary. Isothermal sections of the Ni–Mn–Ga ternary phase diagram at 1073 and 1273 K were investigated over a wide range of alloy
compositions. The range of the β-Ni2MnGa phase, its equilibria with the γ-(Mn, Ni), α′-Ni3Ga, and γ-Ni3Ga2 phases, and the liquidus and solidus lines were determined experimentally. The aging effect on the shape memory effect (SME)
of Ni2MnGa sputtered films was also investigated. The two-way SME of the constraint-aged films was confirmed by the temperature
change. 相似文献
3.
Makoto Ohtsuka Christina Wedel Kimio Itagaki 《Monatshefte für Chemie / Chemical Monthly》2005,16(6):1909-1914
Isothermal sections of the Ni–Mn–Ga ternary phase diagram at 1073 and 1273 K were investigated over a wide range of alloy
compositions. The range of the β-Ni2MnGa phase, its equilibria with the γ-(Mn, Ni), α′-Ni3Ga, and γ-Ni3Ga2 phases, and the liquidus and solidus lines were determined experimentally. The aging effect on the shape memory effect (SME)
of Ni2MnGa sputtered films was also investigated. The two-way SME of the constraint-aged films was confirmed by the temperature
change. 相似文献
4.
M. Teresa Barros João Martins Rui M. Pinto Mónica S. Santos Helena M. V. M. Soares 《Journal of solution chemistry》2009,38(12):1504-1519
As part of a search for environmentally friendly metal chelating ligands, the stability constants of N, N′-ethylenedi-L-cysteine
(EC) complexes with Ca(II), Cu(II), Mg(II) and Mn(II) were determined by potentiometry with a glass electrode in aqueous solutions
containing 0.1 mol⋅L−1 KCl at 25 °C. Final models are proposed. For the Ca(II)–EC system, the overall stability constants are log 10
β
CaHL=14.53±0.03, log 10
β
CaL=4.79±0.01 and log 10
β
CaL2=8.38±0.04. For the M(II)–EC systems, where M=Cu(II) or Mg(II), the overall stability constants are log10
β
CuHL=31.19±0.02 and log 10
β
CuL=27.02±0.06 for Cu(II), and are log 10
β
MgHL=14.84±0.02 and log 10
β
MgL=6.164±0.008 for Mg(II). For the Mn(II)–EC system, the overall stability constant is log 10
β
MnL=10.12±0.01.
Metal–chelate speciations simulations showed that EC is an efficient chelating agent for Cd(II), Co(II), Cu(II), Ni(II), Pb(II)
and Zn(II) for pH≥7. 相似文献
5.
Nakaruk A. Lin C. Y. W. Channei D. Koshy P. Sorrell C. C. 《Journal of Sol-Gel Science and Technology》2012,61(1):175-178
Thin films of TiO2 doped with Fe and Mn were deposited on F-doped SnO2-coated glass by spin coating. Dopant concentrations of 3–7 wt% (metal basis) were used. The structural, chemical, and optical
characteristics of the films were investigated. Laser Raman microspectroscopy and glancing angle X-ray diffraction data showed
that the films consisted of the anatase polymorph of TiO2. X-ray photoelectron spectroscopy data indicated the presence of Fe3+, Mn4+, and Mn3+ in the doped films, as predicted by calculated thermodynamic stability diagrams, and the occurrence of atomic disorder and
associated structural distortion. Ultraviolet–visible spectrophotometry data showed that the optical indirect band gap of
the films decreased significantly with increasing dopant levels, from 3.36 eV (undoped) to 2.95 eV (7 wt% Fe) and 2.90 eV
(7 wt% Mn). These improvements are attributed to single (Fe) or multiple (Mn) shallow electron/hole trapping sites associated
with the dopant ions. 相似文献
6.
β-sialon ceramics sintered with yttria additives have been studied with the use of an electron probe X-ray analysis (EPMA).
Sialon ceramics were prepared from a carbothermally derived β-sialon powder and then sintered in a nitrogen atmosphere with
yttria admixture. The above process was followed by annealing in flowing nitrogen. Scanning electron microscope (SEM) observations
have shown that the sintered material contains a glassy phase (Y-Si-Al-O-N) on the grain boundaries. X-ray diffraction (XRD)
after annealing in nitrogen revealed the presence of a considerable amount of yttrium aluminium garnet (YAG). The higher voltage
of 30 kV was used in order to excite the yttrium Kα radiation (14.96 keV) at an appropriate overvoltage ratio because in some phases of the material, the disappearance of the
yttrium Lα line has been observed during EPMA examination at an accelerating voltage of 15 kV in energy dispersive spectra (EDS). The
intensity of the yttrium Kα line was sufficiently high, while the Y Lα line was not seen in the ED spectrum. Because the position of the yttrium Lα line (1.922 keV) is very close to the Si (K) absorption edge (1.84 keV), the strong absorption at this edge is probably responsible
for the effect. This result should be considered as a serious warning in the case of EPMA (EDS) studies on compounds or mixtures
suspected to contain both silicon and yttrium, because at electrons energies lower than 15 keV, the presence of yttrium in
materials can go unnoticed. In wavelength dispersive spectra (WDS) obtained at 15 keV the intensity of the yttrium Lα line was also very low but measurable. 相似文献
7.
Mosqueda Y Pomares M Pérez-Cappe EL Miranda A Fariñas JC Larrea MT 《Analytical and bioanalytical chemistry》2006,386(6):1855-1862
An analytical method was developed for the determination of three major (Li, Ni and Co) and fourteen minor or trace elements
(Al, Ba, Ca, Cu, Cr, Fe, K, Mg, Mn, Na, Si, Sr, Ti and V) in LiNi1−x
Co
x
O2 (x = 0.2–0.8) ceramic powders by inductively coupled plasma optical emission spectrometry. Sample dissolution was achieved by
25% nitric acid digestion in a microwave oven. For each element, an analytical line free from spectral interferences was selected.
A detailed study of matrix effects over a wide interval of total excitation energy (TEE) lines (1.62–16.50 eV) was performed
at near-robust plasma conditions. A remarkable enhancement in atomic lines with TEE <4 eV was noticed, whereas a significant
reduction in atomic and ionic lines with TEE >4 eV was observed. The extrapolation to infinite dilution method was successfully
used to overcome these nonspectroscopic interferences. Detection limits (3σ) varied from 0.21 mg kg−1 for Sr to 49.7 mg kg−1 for Na. The precision of determination (obtained as the relative standard deviation) was lower than 1% for the major elements
Li, Ni and Co and between 0.69 and 10% for minor and trace elements. The accuracy of the method ranged from 91 to 101% for
major elements, and from 90 to 110%, or close to this range, for most of the impurities in both of the samples studied.
相似文献
8.
Yuanyuan Cong Rena Kasimu Hui Dai Palida Abulizi Ping Sheng Xiaoming Gao Pengfei Tu 《Chemistry of Natural Compounds》2009,45(1):11-13
A neutral polysaccharide Gi-A1 was isolated from the roots of Glycyrrhiza inflata Bat. It had a molecular mass of over 2000 kDa
and showed [α]D20 + 81.4° (c 1.05, H2O). Acid hydrolysis and methylation analysis indicated that Gi-A1 was mainly composed of α-D-glucose, α-L-arabinose, and α-D-galactose
with a molar ratio of 8.0:1.8:1.0. It can significantly stimulate spleen cell proliferation in vitro (P < 0.01).
Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 13–14, January–February, 2009. 相似文献
9.
Zoran Samard?ijaRID=""ID="" To whom correspondence should be addressed Darko Makovec Miran ?eh 《Mikrochimica acta》2000,132(2-4):383-386
Yttrium-doped BaTiO3 ceramics have been studied as a potential material for positive temperature coefficient resistors (PTCR). The mechanism of
Y incorporation into BaTiO3 plays an important role for displaying good electrical properties. Determination of the amount of yttrium in the BaTiO3 as well as microstructure characterization of the samples were performed using SEM, EDS and WDS analysis. An optimized trace
element WDS quantitative analysis was applied to determine elemental concentrations for Ba, Ti and Y in the samples as accurately
as possible. BaTiO3 and Y2O3 were used as standards. Analysis was undertaken using a JEOL JXA 840A electron probe microanalyzer. WDS X-ray intensity measurements
were performed under 20 kV, 50 nA beam current and 0.2% preset standard counting deviation (σc) using a PET crystal. Measured k-ratios were quantified by ZAF matrix correction. Average results of WDS quantitative analysis showed 20.17 ± 0.08 at % Ti,
19.95 ± 0.09 at % Ba, 0.22 ± 0.03 at % Y, and 59.66 at % O. The results suggest incorporation of yttrium in the BaTiO3 preferentially at the Ba-sites, however partial incorporation of Y at Ti-sites could not be excluded. 相似文献
10.
The intensities of the Fe L lines/bands l = L3M1, η = L2M1, α1,2 = L3M4,5, β1 = L2M4, and β3,4 = L1M2,3 were measured for pure Fe and Fe3O4 using a TAP crystal as the dispersing element. The energy of the exciting electrons, E0, was varied in the range 5 ≤ E0 ≤ 25 keV.
For pure Fe the following results were obtained. The net peak height ratio Ll/Lα remains relatively constant with varying
E0 at approximately 14%. The E0 dependence of Lη is similar to that of Ll, although Lη is less intense than Ll by a factor of 7. Lβ1/Lα decreases from 20% for E0 = 5 keV to about 5% for 25 keV. Lβ3,4 behaves like Lβ1 but is weaker by a factor of 15.
For Fe3O4 a much weaker intensity of Lα was observed which can be partially explained by its stronger absorption. Again, the E0 dependence of Ll and Lη is similar with Ll/Lα = 19% and Lη/Lα = 4%. Lβ1 and Lβ3,4 show a comparable E0 dependence. Lβ1/Lα decreases from 50% for E0 = 5 keV to 34% for 25 keV. Lβ3,4 is weaker than Lβ1 by a factor of about 25.
The observed E0 dependence of the different lines was used to estimate a set of mass absorption coefficients. Our value for Lα in Fe agrees
well with other data which were deduced from variable E0 measurements but differs considerably from data given by Heinrich and Henke. 相似文献
11.
The K-stearate/glycerol (KC18/Gl) binary system was studied at mole fractions of stearate of x
KC18 = 0.10, 0.25, 0.30 and 0.50. Small- and wide-angle X-ray diffraction (XRD) measurements were combined with differential scanning
calorimetry (DSC) measurements at different temperatures. The investigations were intended to verify the previously published
phase diagram and were targeted at the confirmation of the gel-like (G1) phase and the isotropic (I) phase. The XRD and DSC measurements lead to the conclusion that the G1 phase as well as the I phase, the existence of which had been proposed from texture observations, do in fact not exist. Consequently,
a correction of the preliminary phase diagram is given. This corrected phase diagram reveals the crystalline phase (C) ⇆ gel
phase (G) ⇆ hexagonal phase (Hα) ⇆ isotropic, micellar phase phase transitions for low KC18 concentrations of x
KC18 = 0.15–0.3 and the C ⇆ G ⇆ lamellar phase (Lα) phase transitions for concentrations about or higher than x
KC18 = 0.35. The C, G, Lα and Hα phases have been further characterized by structural parameters (characteristic d values) as a function of temperature. The phase transitions C ⇆ G, G ⇆ Lα and G ⇆ Hα correlate with sharp shifts in the d value of the first small-angle reflections.
Received: 20 April 1999 Accepted: 28 July 1999 相似文献
12.
A new high α1A adrenoreceptor (α1AAR) expression cell membrane chromatography (CMC) method was developed for characterization of α1AAR binding interactions. HEK293 α1A cell line, which expresses stably high levels of α1AAR, was used to prepare the stationary phase in the CMC model. The HEK293 α1A/CMC-offline-HPLC system was applied to specifically recognize the ligands which interact with the α1AAR, and the dissociation equilibrium constants (K
D) obtained from the model were (1.87 ± 0.13) × 10−6 M for tamsulosin, (2.86 ± 0.20) × 10−6 M for 5-methylurapidil, (3.01 ± 0.19) × 10−6 M for doxazosin, (3.44 ± 0.19) × 10−6 M for terazosin, (3.50 ± 0.21) × 10−6 M for alfuzosin, and (7.57 ± 0.31) × 10−6 M for phentolamine, respectively. The competitive binding study between tamsulosin and terazosin indicated that the two drugs
interacted at the common binding site of α1AAR. However, that was not the case between tamsulosin and oxymetazoline. The results had a positive correlation with those
from radioligand binding assay and indicated that the CMC method combined modified competitive binding could be a quick and
efficient way for characterizing the drug–receptor interactions. 相似文献
13.
An effective, rapid and simple analytical method for the determination of Na, K, Ca, Mg, Cd, Pb, Ba, Fe, Mn, Sr, Zr, Cu, Zn
and Al at mg kg−1 levels in the ultrapure salts MgCl2 and CaCl2 using optical emission spectrometry was developed. Optimisation of the operation conditions was performed with real samples
of ultrapure MgCl2 and CaCl2. The results of the determination with multi-elemental water standards were compared to the internal standardisation, the
standard addition method, and the maximum allowable content of the above mentioned elements in pure chemicals. The method
was shown to be very sensitive with the following limits of detection: Na 1.01, K 3.12, Ca 0.263, Mg 0.275, Cd 0.0832, Pb
0.482, Ba 0.0153, Fe 0.0528, Mn 0.0473, Sr 0.0203, Zr 0.638, Cu 0.0732, Zn 0.0686 and Al 0.459 (all in mg kg−1). The method exhibited satisfactory precision, high analytical recoveries, linear responses of an accuracy of at least 4
orders of magnitude and low contamination susceptibility. 相似文献
14.
Praher B Rössler R Arenholz E Heitz J Pedarnig JD 《Analytical and bioanalytical chemistry》2011,400(10):3367-3375
Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is employed for quantitative determination of oxide
concentrations in multi-component materials. Industrial oxide materials from steel industry are laser ablated in air, and
the optical plasma emission is collected by spectrometers and gated detectors. The temperature and electron number density
of laser-induced plasma are determined from measured LIBS spectra. Emission lines of aluminium (Al), calcium (Ca), iron (Fe),
manganese (Mn), magnesium (Mg), silicon (Si), titanium (Ti), and chromium (Cr) of low self-absorption are selected, and the
concentration of oxides CaO, Al2O3, MgO, SiO2, FeO, MnO, TiO2, and Cr2O3 is calculated by CF-LIBS analysis. For all sample materials investigated, we find good match of calculated concentration
values (C
CF) with nominal concentration values (C
N). The relative error in oxide concentration, e
r = |C
CF − C
N|/C
N, decreases with increasing concentration and it is e
r ≤ 100% for concentration C
N ≥ 1 wt.%. The CF-LIBS results are stable against fluctuations of experimental parameters. The variation of laser pulse energy
over a large range changes the error by less than 10% for major oxides (C
N ≥ 10 wt.%). The results indicate that CF-LIBS method can be employed for fast and stable quantitative compositional analysis
of multi-component materials. 相似文献
15.
Enzyme-linked immunosorbent assay (ELISA), horseradish peroxidase (HRP)-catalyzed fluorescent reaction, and oxalate chemiluminescence
imaging analysis have been combined to develop a sensitive, simple, and rapid method for analysis of interferon alpha (α-IFN)
in human serum samples. A typical “sandwich type” immunoassay was used. Reaction of o-phenylenediamine (OPD) with hydrogen peroxide (H2O2), catalyzed by HRP, produced 2,3-diaminophenazine (PDA), which was detected by chemiluminescence imaging analysis with the
bis(2,4,6-trichlorophenyl)oxalate (TCPO)–H2O2–glyoxaline–PDA chemiluminescent system. The TCPO chemiluminescent imaging system is more sensitive and the chemiluminescence
quantum yield is at least five times higher than for the luminol–H2O2–HRP–PIP (p-iodophenol) chemiluminescent imaging system. The results showed there was a very good linear correlation between response
and amount of α-IFN in the range 1.3–156.0 pg mL−1 (R = 0.9991) and the detection limit was 0.8 pg mL−1 (S/N=3). The relative standard deviation (n = 9) was 4.7%. The proposed method has been used for successful analysis of the amount of α-IFN in human serum. The results
obtained compared well with those obtained by conventional colorimetric ELISA and luminol chemiluminescent ELISA.
Figure Procedures of the proposed method 相似文献
16.
Pranesh Muralidhar Elmar Bonaccurso Günter K. Auernhammer Hans-Jürgen Butt 《Colloid and polymer science》2011,289(14):1609-1615
The initial stages of spontaneous spreading of a solvent drop (toluene) on the surface of a soluble polymer (polystyrene)
have been studied with a high-speed camera. For drops of 1–4 μL volume, the increase in contact radius r can be described by a power law r μ ta r \propto {t^{\alpha }} , with the spreading exponent α = 0.50 and for the first ≈8 ms. Thereafter, the three-phase contact line was pinned leading to a macroscopic static contact
angle of Θ0 = 12–15°. The insoluble liquids ethanol (α = 0.47, Θ0 = 0) and water (α = 0.35, Θ0 = 90°) showed a slower spreading. We attribute the fast spreading of toluene to the strong interaction with the polymer,
like in reactive wetting. The finite macroscopic contact angle indicates the formation of a ridge by softening of polystyrene
due to permeated toluene and the subsequent plastic deformation by the surface tension of the liquid. This interpretation
is supported by experiments on polymers grafted from a silicon wafer. Toluene completely wets polymer brush surfaces. Transport
of toluene through the vapor phase plays a significant role. 相似文献
17.
Mohammad Wasim Nasir Khalid Azeem Asif Mohammad Arif Jamshed Hussain Zaidi 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1153-1159
Mineral contents of strawberry, collected from different farms of Islamabad were analysed by semi-absolute k
0-instrumental neutron activation analysis and atomic absorption spectrophotometry. The samples were irradiated at two research
reactors located in Pakistan Institute of Nuclear Science & Technology (PINSTECH), Islamabad. The analytical methodologies
were validated by analysing reference materials, IAEA-336 (lichen) and IAEA-V-10 (hay powder). In all the samples, a total
of 26 elements were quantified, among them 16 elements (Ca, Cd, Cl, Co, Cr, Cs, Fe, K, Mg, Mn, Na, Pb, Ru, Sc, Sr and Zn)
were found in all the samples. The determined elemental concentrations in strawberry were compared with the reported values
from other countries. In comparison with the mineral contents of other fruits, strawberry stands best source of Mn and the
second most important source of K after banana. Intake of trace metals through this source was calculated and it was found
that strawberry provides Mn (1.95–3.68 mg/kg), Cr (19.2–46.3 × 10−3 mg/kg), Fe (3.45–8.72 mg/kg), K (1,520–1,670 mg/kg) and Mg (100–220 mg/kg), which forms 26, 19, 14, 7 and 7% of the recommended
dietary allowances for the respective metals. The daily intake of Cd and Pb were compared with the provisional tolerable weekly
intake defined by FAO/WHO. 相似文献
18.
A simple implementation of third-order perturbation theory applied to a multireference zero-order wavefunction is presented.
Two different partitions of the Hamiltonian (M?ller–Plesset baricentric and Epstein–Nesbet) are considered. Two test cases,
CH2 and N2, are examined. The third-order results are shown to be in good agreement in either partition and are generally an improvement
with respect to the second-order results. The phenomenon of intruder states, absent in Epstein–Nesbet, appears to be magnified
in the M?ller–Plesset partition.
Received: 22 November 2001 / Accepted: 22 February 2002 / Published online: 3 May 2002 相似文献
19.
Contracted Gaussian-type function (CGTF) basis sets are reported for valence p orbitals of the six alkali and alkaline-earth atoms Li, Be, Na, Mg, K, and Ca for molecular applications. These sets are
constructed by Roothaan–Hartree–Fock calculations for the ns → np excited states of atoms, in which both linear and nonlinear parameters of CGTFs are variationally optimized. The present
CGTF sets reproduce well the numerical Hartree–Fock ns → np excitation energies: the largest error is 0.0009 hartrees for Li. New CGTFs are tested with diatomic Li2, Na2, K2, and MH molecules, where M = Li, Be, Na, Mg, K, and Ca, by self-consistent-field (SCF) and multiconfiguration SCF calculations.
The resultant spectroscopic constants compare well with those of more elaborate calculations and are sufficiently close to
experimental values, supporting the efficiency of the present set for the valence p orbitals.
Received: 9 July 1998 / Accepted: 17 September 1998 / Published online: 1 February 1999 相似文献
20.
Microemulsion polymerization of styrene using a polymerizable nonionic surfactant and a cationic surfactant 总被引:9,自引:0,他引:9
High polymer/surfactant weight ratios (up to about 15:1) of polystyrene microlatexes have been successfully produced by microemulsion
polymerization using a small amount of polymerizable surfactant, ω-methoxypoly(ethylene oxide)40 undecyl α-methacrylate macromonomer (PEO-R-MA-40), and cetyltrimethylammonium bromide (CTAB). After generating “seeding particles”
in a ternary microemulsion containing only 0.2 wt% CTAB and 0.1 wt% styrene, the additional styrene containing less than 1 wt%
PEO-R-MA-40 was added dropwise to the polymerized microemulsion for a period of about 4 h at room temperature. PEO-R-MA-40
copolymerized readily with styrene. The stable microlatexes were bluish-transparent at a lower polymer content and became
bluish-opaque at a higher polymer content. Nearly monodisperse latex particles with diameters ranging from 50 to 80 nm and
their molar masses ranging from 0.6 to 1.6 × 106 g/mol could be obtained by varying the polymerization conditions. The dependence of the number of particles per milliliter
of microlatex, the latex particle size and the copolymer molar mass on the polymerization time is discussed in conjunction
with the effect of the macromonomer concentration.
Received: 25 October/2000 Accepted: 2 February 2001 相似文献