Comparative study of iron-containing haematinics from the point of view of their magnetic properties

The dynamic magnetic susceptibility of several haematinics in which iron is present as antiferromagnetic salts or iron oxyhydroxide nanoparticles has been measured. Among other parameters, the temperature dependence of the AC susceptibility of each compound acts as a fingerprint that informs about microstructural aspects of the presence of iron. The physicochemical characterisation of these compounds is of great relevance with respect to their bioavailability in the treatment of iron deficiency anaemia.     

Magnetic study of iron-containing carbon nanotubes: Feasibility for magnetic hyperthermia

We present a detailed magnetic study of iron containing carbon nanotubes (Fe-CNT), which highlights their potential for contactless magnetic heating in hyperthermia cancer treatment. Magnetic field dependent AC inductive heating experiments on Fe-CNT dispersions show a substantial temperature increase of Fe-CNT dispersions in applied AC magnetic fields. DC and AC magnetization studies have been done in order to elucidate the heating mechanism. We observe a different magnetic response of Fe-CNT powder compared to Fe-CNT dispersed in aqueous solution, e.g., ferromagnetic Fe-CNT in powder do not show any hysteresis when being dispersed in liquid. Our data indicate the motion of Fe-CNT in liquid in applied magnetic fields.     

Structure and composition of iron-containing langmuir-blodgett films

Summary The composition of differently prepared Langmuir-Blodgett multilayers of ferric arachidate has been investigated by means of absorption M?ssbauer spectroscopy and heavy-ion-induced mass spectrometry. We found that the iron concentration in qualitatively good films is 3.5 times higher than the stoichiometric value. Antiferromagnetic ordering in this two-dimensional model substance can be observed when the Fe−Fe distance in the layers is about 0.3 nm or below. The area density of the iron atoms in the planes decreases with decreasingpH values of the subphase which also leads to a disappearance of the long-range magnetic ordering and to a decrease of the Debye temperature of the films which is linearly dependent on the iron concentration in the films. Paper presented at the ICAME-95, Rimini, 10–16 September 1995     

Magnetism of iron-containing MCM-41 spheres

Iron species were loaded into the mesopores of MCM-41 spheres by incipient wetness impregnation procedure with Fe(ACAC)₃ as the precursor. The magnetism of the samples was studied by vibrating sample magnetometer (VSM), diffuse reflectance ultraviolet–visible (DRUV-vis) spectra and Mossbauer spectra. The results show that the magnetic behavior of the iron-loaded MCM-41 spheres depends on the content of iron loading, valence, and coordination state of iron ions, testing temperature and the atmosphere for the pyrolysis of the iron precursor.     

Comparative analysis of the bioactivity of materials

Bioactive materials are characterized by a high rate of formation of a carbonate-containing hydroxyapatite contact layer at the implant-bone interface and by a moderate resorption capacity in weakly acidic media. In vitro tests simulating the precipitation of hydroxyapatite from interstitial tissue fluid at the surface of a material are performed to evaluate the bioactivity of a broad range of materials. The data indicate that the silicon-containing material is characterized by the highest bioactivity in the series of calcium hydroxyapatites.     

Spin coupling in iron-containing proteins and model complexes

In the field of transition metals in biology we are concerned with a variety of homo- and hetero-polynuclear metal clusters which exhibit spin coupling. A further example for spin coupling in this field is provided by mononuclear transition metal complexes, with the paramagnetic metal site and an additional nonmetallic site forming a spin-coupled system. For both types of spin-coupled systems we present examples here, and we discuss the influence of localized and delocalized mixed-valence states, and the strength of superexchange, spin-dipolar and double-exchange contributions to spin coupling.     

Comparative study of LiNi0.05Mn1.95O4 powders prepared by different materials for Li-ion battery

LiNi_0.05Mn_1.95O₄ powders were prepared by manganese tetraoxide (MTO) and electrolytic manganese dioxide (EMD). The phase identification, surface morphology, and electrochemical properties of the prepared powders were studied by X-ray diffraction, scanning electron microscopy, cyclic voltammetry, and galvanostatic charge?Cdischarge experiments. Compared to LiNi_0.05Mn_1.95O₄ powders prepared by EMD, LiNi_0.05Mn_1.95O₄ powders prepared by MTO show better crystallinity. Both powders possess a typical cubic structure with uniform particle size. The specific capacity and coulombic efficiency of LiNi_0.05Mn_1.95O₄ powders prepared by MTO are higher than the one prepared by EMD. The capacity retention of LiNi_0.05Mn_1.95O₄ powders prepared by MTO cycled 30 times at room temperature and 55?°C are 98.3% and 90.6%, respectively, which are much higher than those of 86.63% and 77.7% for the one prepared by EMD. LiNi_0.05Mn_1.95O₄ powders prepared by MTO show higher specific capacity and better cycling performance than the one prepared by EMD.     

Point defects and orientation-dependent transport of matter and charge in iron-containing olivines

The variation of the oxygen content, x_O, of synthetic fayalite (Fe₂SiO₄) single crystals was investigated thermogravimetrically at 1130 °C as a function of the oxygen activity, a_O2 (= P_O2/P_O2° ≈ f_O2/f_O2° with P_O2° ≈ f_O2° = 1 bar ≈ 1 atm). It was found that x_O varies less in fayalite single crystals than in polycrystalline Fe₂SiO₄ studied earlier. The majority defects are most likely cation vacancies, (V_Me²⁺)″, ferric ions on M-sites, (Fe³⁺_Me²⁺), and ferric ions on Si-sites, (Fe³⁺_Si⁴⁺)′. Furthermore, the diffusion of iron in synthetic olivine single crystals ((Fe_xMg_1 − x)₂SiO₄) was studied at 1130 °C as a function of orientation, oxygen activity, and cationic composition. The observed oxygen activity dependencies suggest that cations move via different types of cation vacancies, most likely isolated vacancies, (V_Fe²⁺)″, and possibly neutral associates, {2(Fe³⁺_Me²⁺) ⋅ (V_Me²⁺)^′ ? ′}^x, the latter being minority defects. In addition, the electrical conductivity, σ, of fayalite single crystals was investigated as a function of orientation and oxygen activity within the stability field of fayalite at 1130 °C. The observed oxygen activity dependencies are compatible with (V_Me²⁺)^′ ? ′, (Fe³⁺_Me²⁺), and (Fe³⁺_Si⁴⁺)′ being the majority point defects at high a_O2 and with h^⋅ and e′ as the majority defects at low a_O2. The electrical conduction in fayalite is governed by contributions of electrons and holes. This extended point defect model for fayalite is also compatible with data for the variation of the oxygen content and for the iron tracer diffusion.     

Magnetic properties of iron-containing coatings formed by plasma-electrolytic oxidation

The magnetic properties of iron-containing coatings formed on aluminum by plasma-electrolytic oxidation were investigated. It was shown that the magnetic state of the samples studied is most likely induced by chemically inhomogeneous (multiphase) ferromagnetic particles.     

Corelationship between local structure and water purifying ability of iron-containing waste glasses

A relationship between the structure and water purifying ability of waste glass prepared from household garbage and Fe₂O₃ was examined by ⁵⁷Fe-Mössbauer and induced coupled plasma (ICP) measurements. From the Debye temperature of waste glass, Fe^II proved to be loosely bound in the glass network as a network modifier. Dissolution amount of Fe^III into artificial drain can be controlled from 0.14 to 0.35 mg/l by changing the Fe₂O₃ content. It proved that chemical oxygen demand (COD) decreases in proportion to the content of Fe^III, indicating that iron causes decomposition of organic and phosphorus compounds.     

Water cleaning ability and local structure of iron-containing soda-lime silicate glass

A relationship between waste-water cleaning ability and local structure of iron-containing soda-lime silicate glass, 15Na₂O·15CaO·xFe₂O₃·(70-x)SiO₂ (x?= 10–50 in mass%), abbreviated as NCFSx glass, was investigated by means of ⁵⁷Fe-Mössbauer spectroscopy, redox titration with KMnO₄ for the determination of chemical oxygen demand (COD) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Mössbauer spectra of NCFSx glass with “x” of 10 and 30 were composed of two doublets: one due to Fe^IIIO₄ tetrahedra (T _d) with isomer shift (δ) of 0.23–0.26 mm s^???1 and quadrupole splitting (Δ) 1.01–1.04 mm s^???1, and the other due to Fe^IIO₆ octahedra (O _h) with δ of 1.00–1.03 mm s^???1 and Δ of 2.03–2.05 mm s^???1. Absorption area for Fe^II(T _d) was decreased from 9.7 to 6.5 and 0.0 % when “x” was increased from 10 to 30 and 50. A leaching test performed with 500 mL of artificial waste water and 2.0 g of NCFS50 revealed waste-water cleaning ability of soda-lime glass, e.g., COD was reduced from 280 to 55.2 mg L^???1 after 10 day-leaching. After 10 day-leaching, it proved that iron was dissolved into waste water to a level of 5.3 $_{7} \times 10^{-1}$  mg L^???1. These results prove that organic matter could be effectively decomposed with iron-containing soda-lime silicate glass.     

几种傅里叶子的深入比较研究

用于模式识别的傅里叶子主要有基于极半径函数、转角函数和曲率函数等三种方法 ,通过比较研究 ,找出一种运算简便且精度高的傅里叶子。对不同的图形用三种方法分别计算出原函数和傅里叶频谱 ,然后从大到小依次选取k个 (k =1,2 ,… ,N)傅里叶系数进行反变换 ,计算出反变换函数与原函数之间存在的误差 ,根据误差随k变化的曲线判断三种方法的优劣。实验结果表明 ,基于极半径函数的傅里叶子最为理想。将它用于孢子的识别和计数 ,正确识别率达 99%。     

The characterisation of iron-containing intermetallic phases within industrially cast aluminium

⁵⁷Fe conversion electron Mössbauer spectroscopy has been used to investigate the intermetallic phases near the surface of a D.C. cast aluminium ingot. The CEMS data is used with SAAES (selected area Auger electron spectroscopy) and SAXPS (selected area X-ray photoelectron spectroscopy) data to propose a model of the surface region above the grain boundaries.     

全息记录介质的评价方法及特性研究

本文在综合前人工作的基础上,提出了一套评价全息记录介质的方法。测量和研究了重铬酸盐明胶和卤化银介质的某些特性。     

Comparative study of large-mode holey and conventional fibers

Little information exists regarding how large-mode holey fibers compare, in practical terms, with their conventional counterparts. We present what is to our knowledge the first experimental study of mode area and bend loss for a range of large-mode holey and conventional fibers. It is demonstrated here that large-mode holey fibers exhibit mode areas and bending losses that are comparable to those of conventional fibers at 1.55mu . However, the novel wavelength dependence of the numerical aperture in a holey fiber offers a significant advantage for broadband and short-wavelength applications in which single-mode operation is required.     

Comparative simulation study of colloidal gels and glasses

Using computer simulations, we identify the mechanisms causing aggregation and structural arrest of colloidal suspensions interacting with a short-ranged attraction at moderate and high densities. Two different nonergodicity transitions are observed. As the density is increased, a glass transition takes place, driven by excluded volume effects. In contrast, at moderate densities, gelation is approached as the strength of the attraction increases. At high density and interaction strength, both transitions merge, and a logarithmic decay in the correlation function is observed. All of these features are correctly predicted by mode coupling theory.     

Comparative study of charged multiplicity distributions

A compilation is made of charged multiplicity distributions for $\text{π}{}^{\mathrm{\pm }}\text{,}\text{K}{}^{\mathrm{\pm }}\text{,}\text{p and}\text{p}$ interactions on hydrogen. Besides the usually studied parameters 〈 n_c〉 and D, the skewness γ₁, the kurtosis γ₂ and the mode are closely examined. It is found that γ₁ and γ₂ may be considered as constant for p_lab > 10 GeV/c. As a consequence, all the data are well parametrized by means of the Edgeworth expansion, describing the approach to a Gaussian when the number of production centres is increased. The constancy of γ₁ would indicate that this number does not grow in the energy domain studied. Limited to the first order, the Edgeworth expansion is a useful alternative to the Czyzewski-Rybicki formula for expressing all the regularities of the multiplicity distributions.