共查询到20条相似文献,搜索用时 31 毫秒
1.
X. Tan J. Zhou F. Liu Y. Peng B. Zhao 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(4):555-564
Density functional theory within general gradient approximation (GGA) has
been used to investigate sub-monolayer carbon atom adsorbed on Fe(100) as a
function of coverage. The carbon atoms prefer to adsorb in the fourfold
hollow site and bind strongly with the Fe surfaces. There is a substantial
and strong coverage dependence of the carbon-induced expansion of the first
interlayer spacing, reflecting a weakening of Fe–Fe bonds between the two
outermost substrate layers. Some charge is found to transfer from substrate
Fe to the adsorbate C atoms, which is responsible for the increase of work
function. The density of states (DOS) analysis indicates the bonding of
carbon with the first surface layer Fe atoms is primarily due to the
interaction between Fe 3dx2-y2, xy and C 2px, y orbitals, and the
bonding of carbon with the second surface layer Fe atom that sits directly
below the carbon atom is mainly from interaction between the minority spin
Fe 3dz2 and C 2pz orbitals. 相似文献
2.
Two new ligands derived from phloroglucinol 2-{[(4-methoxy benzoyl ) oxy ] } methyl benzoic acid[L1] and 2-{[(4-methyl benzoyl
)oxy] methyl} benzoic acid[L2] were synthesized. The solid complex Eu(III)-L2 has been synthesised and characterized by elemental
analysis ,UV and IR spectra. The reaction of Eu(III) with the two synthesized ligands has been investigated in I = 0.1 mol dm-3 p-toluene sulfonate by cyclic voltammetry and square wave voltammetry. The reaction of Eu (III)–L1 and Eu (III)–L2 binary
complexes with nucleotide 5′-AMP , 5′-ADP ,5′-ATP , 5′- GMP , 5′-IMP , and 5′-CMP has been investigated using UV, fluorescence
and electrochemical methods. The experimental conditions were selected such that self-association of the nucleotides and their
complexes was negligibly small, that is, the monomeric complexes were studied. The interaction of the Eu(III)–L1 or L 2 solid
complexes with calf-thymus DNA has been investigated by fluorescence and electrochemical methods including cyclic voltammetery(CV)
,differential pulse polarography (DPP) and square wave voltammetry (SWV) on a glassy carbon electrode. The fluorescence intensity
of Eu(III)-L2 complex was enhanced with the addition of DNA. Under optimal conditions in phosphate buffer pH 7.0 at 25 °C
the linear range is 3–20 μM for calf thymus DNA (CT–DNA) and the corresponding determination limit is 1.8 μM. 相似文献
3.
Ruslan Sergiienko Sunghoon Kim Etsuro Shibata Takashi Nakamura 《Journal of nanoparticle research》2010,12(2):481-491
For the first time Fe–Pt alloy included carbon nanocapsules were synthesized by an electric plasma discharge in an ultrasonic
cavitation field of liquid ethanol. This contrasts the extensively used chemical synthesis methods which produce uncoated
Fe–Pt alloy nanoparticles. We proposed that the as-synthesized Fe–Pt alloy included carbon nanocapsules are potentially useful
in biomedical applications. Thereby an aim of this work was to coat the Fe–Pt alloy nanoparticles by graphite shells using
plasma discharge in liquid ethanol and to study the structure and magnetic properties of the carbon encapsulated Fe–Pt alloy
nanoparticles. The core–shell structured nanoparticles were characterized by transmission electron microscopy and X-ray diffraction.
These methods revealed the presence of a disordered face-centered cubic (fcc) structure (γFe, Pt) in the cores of the as-synthesized carbon nanocapsules. The as-synthesized carbon nanocapsules showed the soft magnetic
character at room temperature. These carbon nanocapsules may provide a new approach in the transport and delivery of anticancer
drugs. 相似文献
4.
Temporins are short (10–13 amino acids) and linear antimicrobial peptides first isolated from the skin of the European red
frog, Rana temporaria, and are effective against Gram-positive bacteria and Candida albicans. Similarly to other antimicrobial peptides, the association of temporins to lipid membranes has been concluded to underlie
their antimicrobial effects. Accordingly, a detailed understanding of their interactions with phospholipids is needed. We
conjugated a fluorophore (Texas Red) to a Cys containing derivative of temporin B (temB) and investigated its binding to liposomes
by fluorescence spectroscopy. Circular dichroic spectra for the Cys-mutant recorded in the absence and in the presence of
phospholipids were essentially similar to those for temB. A blue shift in the emission spectra and diminished quenching by
ferrocyanide (FCN) of Texas Red labeled temporin B (TRC-temB) were seen in the presence of liposomes. Both of these changes
can be attributed to the insertion of the Texas Red into the hydrophobic region of the bilayer. Resonance energy transfer,
steady state anisotropy, and fluorescence lifetimes further demonstrate the interaction of TRC-temB with liposomes to be enhanced
by negatively charged phospholipids. Instead, cholesterol attenuates the association of TRC-temB with membranes. The interactions
between TRC-temB and liposomes of varying negative surface charge are driven by electrostatics as well as hydrophobicity.
Similarly to native temporin B also TRC-temB forms amyloid type fibers in the presence of negatively charged liposomes. This
property is likely to relate to the cytotoxic activity of this peptide. 相似文献
5.
We have measured the relative luminescence quantum yields and luminescence lifetimes of Tb(III) and Dy(III) ions in complexes
with pyrazole-5-carboxylic acids. Based on study of the time-resolved luminescence spectra of Tb(III) and Dy(III) complexes
with 3-(6-benzodioxanyl)pyrazole-5-carboxylic acid, we have demonstrated the possibility in principle of determining Dy(III)
in the presence of Tb(III) by separating the short-lived component of the luminescence of dysprosium, despite the practically
complete overlap of the analytical bands of dysprosium by the terbium bands. This method was used to determine Dy(III) in
luminescent materials: scandium borates doped with terbium and dysprosium.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 327–331, May–June, 2007. 相似文献
6.
M. Ashok A. V. S. S. Prasad P. Muralidhar Reddy V. Ravinder 《Journal of Applied Spectroscopy》2008,75(6):864-871
Twelve Ru(II) complexes with coordinated amides were synthesized and characterized by elemental, IR, 1H, 13C, 31P NMR, mass, and electronic spectral analysis, along with magnetic and conductance measurements. Molecular formulas and octahedral
structures have been tentatively proposed. These complexes were used as catalysts for the hydrolysis of rivastigmine and neostigmine.
The hydrolyzed products were coupled with 3-methyl benzothiazolinone hydrazone reagent in the presence of sodium metaperiodate
and the resulting colored products were determined spectrophotometrically. The yields of hydrolyzed products were found to
be 98.47% and 99.75% respectively. All the ligands and Ru(II) complexes were screened for antibacterial activity.
Published in Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 867–874, November–December, 2008. 相似文献
7.
1-(4-Aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties
of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy,
circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes
bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal
complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant
activity and be better than standard antioxidants like vitamin C and mannitol.
Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10-5 M, [DNA]=(0-1) ×10-5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(εa – εf) versus [DNA] for the titration of DNA with the complex. 相似文献
8.
M. M. Seleim M. S. Abu-Bakr E. Y. Hashem A. M. El-Zohry 《Journal of Applied Spectroscopy》2009,76(4):554-563
A highly sensitive and selective first-derivative spectrophotometric method has been developed for the determination of aluminum
and iron in mixtures. The method is based on the formation of the binary complexes of aluminum and iron with Alizarin yellow
R (AYR) 5-[4-nitrophenylazo]salicylic acid at pH 2.0 with molar absorptivity of 1.1∙104 l⋅mol–1⋅cm–1. A zero-crossing technique is found suitable for the direct measurement of the first derivative value at the specified wavelength,
so aluminum and iron were thus determined in the ranges 1.3–5.4 μg/ml and 1.1–8.3 μg/ml, respectively, in the presence of
both components. The detection limits were found to be 1.4 ng/ml for aluminum and 2.8 ng/ml for iron. The relative standard
deviations were in all cases less than 1.5%. The proposed method was successfully applied for the simultaneous determination
of aluminum and iron in certified reference aluminum samples. 相似文献
9.
Hao Chen Yongchang Liu Zesheng Yan Yanli Li Lifang Zhang 《Applied Physics A: Materials Science & Processing》2010,98(1):211-217
The three cooling rates of 10, 100, 200 K/min dilatometry experiments are used to investigate the kinetics of the isochronal
austenite (γ) to ferrite (α) transformation of Fe–0.0036wt.%C alloy. “Normal transformation” and “abnormal transformation” have both been observed for
transformations at different cooling rates. In accordance with the thermodynamic characteristics of the γ→α transformation investigated here and previous kinetic considerations, a JMAK-like approach for the kinetics of isochronal
phase transformations was developed that incorporates three overlapping processes: site saturation nucleation, alternate growth
modes (from interface-controlled to diffusion-controlled to interface-controlled growth), as well as impingement for random
distribution nuclei. The JMAK-like approach has been employed to fit the experimental results, and the fitting results show
that for the γ→α transformation of the Fe–C alloy at all applied cooling rates, the growth mode evolves in the corresponding order: from interface-controlled
to diffusion-controlled growth; from interface-controlled to diffusion-controlled to interface-controlled growth; and interface-controlled
growth. 相似文献
10.
Stephen P. Cramer Yuming Xiao Hongxin Wang Yisong Guo Matt C. Smith 《Hyperfine Interactions》2006,170(1-3):47-54
We have used nuclear resonance vibrational spectroscopy (NRVS) to examine the nature of the Fe–S unit. Specifically, vibrational
characteristics have been determined, and through incremental steps in model system complexity, applied to analysis of the
enzyme nitrogenase. This stepwise strategy demonstrates NRVS as a viable bioinorganic tool, and will undoubtedly increase
the application of synchrotron spectroscopy to biological problems. 相似文献
11.
Steven Yueh-Hsiu Wu Ching-Li Tseng Feng-Huei Lin 《Journal of nanoparticle research》2010,12(4):1173-1185
In this study, a magnetic iron-doped calcium sulfide (Fe–CaS) nanoparticle was newly developed and studied for the purpose
of hyperthermia due to its promising magnetic property, adequate biodegradation rate, and relatively good biocompatibility.
Fe–CaS nanoparticles were synthesized by a wet chemical co-precipitation process with heat treatment in a N2 atmosphere, and were subsequently cooled in N2 and exposed to air at a low temperature. The crystal structure of the Fe–CaS nanoparticles was similar to that of the CaS,
which was identified by an X-ray diffractometer (XRD). The particle size was less than 40 nm based on a Debye–Scherrer equation
and transmission electron microscope (TEM) examination. Magnetic properties obtained from the SQUID magnetometer demonstrated
that the synthesized CaS was a diamagnetic property. Once the Fe ions were doped, the synthesized Fe–CaS converted into paramagnetism
which showed no hysteresis loop. Having been heated above 600 °C in N2, the Fe–CaS showed a promising magnetic property to produce enough energy to increase the temperature for hyperthermia. 10 mg/ml
of the Fe–CaS was able to generate heat to elevate the media temperature over 42.5 °C within 6 min. The area of the hysteresis
loop increased with the increasing of the treated temperature, especially at 800 °C for 1 h. This is because more Fe ions
replaced Ca ions in the lattice at the higher heat treatment temperature. The heat production was also increasing with the
increasing of heat treatment temperature, which resulted in an adequate specific absorption ratio (SAR) value, which was found
to be 45.47 W/g at 37 °C under an alternative magnetic field of f = 750 KHz, H = 10 Oe. The in vitro biocompatibility test of the synthesized Fe–CaS nanoparticles examined by the LDH assay showed no cytotoxicity
to 3T3 fibroblast. The result of in vitro cell hyperthermia shows that under magnetic field the Fe–CaS nanoparticles were
able to generate heat and kill the CT-26 cancer cells significantly. We believe that the developed Fe–CaS nanoparticles have
great potential as thermo-seeds for cancer hyperthermia in the near future. 相似文献
12.
Christophe Hecquet Franck Delmotte Marie-Fran?oise Ravet-Krill Sébastien de Rossi Arnaud Jérome Fran?oise Bridou Fran?oise Varnière Evgueni Meltchakov Frédéric Auchère Angelo Giglia Nicola Mahne Stefano Nanaronne 《Applied Physics A: Materials Science & Processing》2009,95(2):401-408
In this paper, we present a study on two-channel multilayer mirrors which can operate at two wavelengths in Extreme Ultraviolet
(EUV) spectral range. We propose a new method to design two-channel EUV multilayer mirrors with enhanced spectral selectivity.
The mirror structure is a stack of two periodic multilayers separated by a buffer layer. We have defined the main parameters
which allow adjustment of the distance between different order Bragg’s peak and of wavelength positions of reflectivity minima.
Two mirrors have been designed and deposited for solar EUV telescope applications by using this method. The first mirror reflects
Fe IX–X line (17.1 nm) and Fe XVI (33.5 nm) lines with attenuation of the He II line (30.4 nm). The second mirror reflects
Fe IX–X and He II lines with attenuation of Fe XV (28.4 nm) and Fe XVI lines. Measurements with synchrotron radiation source
confirm that, in both cases, for these mirrors, we are able to adjust reflectivity maxima (Bragg peak position) and minima.
Such multilayers offer new possibilities for compact design of multi-wavelength EUV telescopes and/or for high spectral selectivity. 相似文献
13.
Xinguo Li Jianyi Shen Bing Zhong Yi Chen Shaoyi Peng Qin Wang Dong Wu 《Hyperfine Interactions》1992,69(1-4):867-870
The effect of second metal component on the structural characteristic of Fe M UFP catalysts was investigated by in situ Mossbauer
spectroscopy. The incorporation of second metal component hinders, the reduction and carburization of iron containing phase
in the presence of H2 and CO, and the degree of hindrance is in the order of Mg Mn Zn due to the interaction between iron and the second metal
component. Consequently, the formation of light olefinic products is in the order of Fe Mg>Fe−Mn·Fe−Zn catalysts consistent
with the F-T synthesis performance.
This work was supported by the National Natural Science Foundation of China 相似文献
14.
Well-crystallized hematite was suspended in water and treated at room-temperature (RT) with sodium borohydride. The product
of the reaction is a highly magnetic black powder, which is stable at RT. The NaBH4 treatment converts about half of the hematite to an amorphous Fe–B alloy and to a small fraction of sub-micron sized, amorphous
metallic-Fe nodules. Heating at 400°C of this composite has resulted in the crystallization and/or oxidation of more than
half of the amorphous Fe–B phase to α-Fe and Fe3O4 and B2O3, respectively. After treatment at 800°C, the metallic Fe and the amorphous Fe–B have completely vanished, and the resulting
product consists of hematite and FeBO3 embedded in the matrix of α-Fe2O3. 相似文献
15.
The amorphization of Fe−Zr multilayers due to ion-beam mixing and solid state reaction is studied in detail using the CEMS
and CXMS. The nature of the amorphous Fe−Zr phase produced by both processes is the same suggesting that diffusion of Fe is
an important mechanism during ion-beam mixing. 相似文献
16.
Haowen Huang Chunhui Li Caiting Qu Shaowen Huang Fang Liu Yunlong Zeng 《Journal of nanoparticle research》2012,14(3):754
In this article, a type of core–shell nanostructure, Au2S/AuAgS/Ag3AuS2-coated gold nanorods (GNRs) with unique optical properties was used as a sensing platform to detect fish sperm DNA (fsDNA).
The prepared core–shell nanorods are positively charged due to the adsorption of the positively charged cetyltrimethylammonium
bromide (CTAB) cations on their surface. fsDNA can form ternary fsDNA–CTAB–nanorod complexes together with CTAB and nanorod,
which provides a useful platform to detect fsDNA through absorption spectra and resonance light scattering (RLS) spectroscopy.
In this sensitive core–shell nanorod sensor, CTAB concentration and the nanoparticle dosage play important roles and have
been investigated. Moreover, the fsDNA–CTAB–nanorod complexes induce a great enhancement of RLS intensity of the core–shell
GNRs and directly proportional to the concentration of fsDNA, reaching a detection limit of about 10−9 mg/mL. This study will be significant for as-prepared core–shell GNRs for future application in biological systems. 相似文献
17.
A new scheme is presented for the physical processes leading to the nuclear fusion reaction d(3He, 4He)p catalyzed by a negatively charged muon μ−. It is shown that the observable rate and yield of the nuclear reaction depend on a chain of ion-molecular reactions involving
the participation of the dμ 3He molecule. New calculations of the nuclear fusion rates in the dμ3He molecule are presented.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 2, 89–94 (25 January 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
18.
Pyrite undergoes a series of exothermic reactions during mine roasting to porous hematite. At low temperatures, the first non-refractive phase to form is ferrous sulphate and could be a cheaper alternative to hematite roasting for the mining industry. In this study, pyrite powder is heated in air at temperatures between 200 and 370 °C for 1 to 256 h in a temperature and time series. The rate of oxidation of pyrite to ferrous sulphate is modelled by combining the Arrhenius equation with the Weibull function to extract reliable thermodynamic data, including the energy of activation, the frequency factor and the overall order of reaction. From the thermodynamic data obtained, two possible oxidation mechanisms are recognized, depending on the bond dissociation energies of the S–S and Fe–S bonds in pyrite. 相似文献
19.
Kaczmarek M 《Journal of fluorescence》2011,21(6):2201-2205
The chemiluminescence (CL) of oxidation of non-steroidal anti-inflammatory drugs (NSAIDs) by Ce(IV) ions, was recorded in
the presence and absence europium(III) ions, in solution of pH ~ 4 of solution. Kinetic curves and CL emission spectra of
the all studied systems were discussed. CL of measurable intensity was observed in the Ce(IV)–NP–Eu(III) reaction system only
in acidic solutions. The CL spectrum rcegistered for this system shows emission bands, typical of Eu(III) ions, with maximum
at λ ~ 600 nm. The chemiluminescent method, based on Eu(III) emission in reaction system of NP-Ce(IV)–Eu(III) in acid solution
was therefore used for the determination of naproxen in mixture of non-steroidal anti-inflammatory drugs. 相似文献
20.
Moamen S. Refat Mohamed M. Ibrahim Mohamed A. A. Moussa 《Journal of Applied Spectroscopy》2012,78(6):772-781
Charge-transfer complexes (CTC) resulting from interactions of 1,3-di[(E)-1-(2-hydroxyphenyl) methylideneamino]-2-propanol Schiff base with some acceptors such as iodine (I2), bromine (Br2), and picric acid (PiA) have been isolated in the solid state in a chloroform solvent at room temperature.
Based on elemental analysis, UV-Vis, infrared, and 1H NMR spectra, and thermogravimetric analysis (TG/DTG) of the solid CTC, [(Schiff)(I2)] (1), [(Schiff)(Br2)] complexes with a ratio of 1:1 and [(Schiff)(PiA)3] complexes with 1:3 have been prepared. In the picric acid complex, infrared and 1H NMR spectroscopic data indicate that the charge-transfer interaction is associated with a hydrogen bonding, whereas the
iodine and bromine complexes were interpreted in terms of the formation of dative ion pairs [Schiff+, I2∙−] and [Schiff+, Br2∙−], respectively. Kinetic parameters were obtained for each stage of thermal degradation of the CT complexes using Coats–Redfern
and Horowitz–Metzger methods. DC electrical properties as a function of temperature of these charge transfer complexes have
been studied. 相似文献