导数光谱法同时测定甲硝唑和维生素B6的研究

本建立了以０．１ｍｏｌ／ＬＨＣｌ为介质，采用三阶导数光谱法，同时测定甲硝唑和维生素Ｂ６的新方法，方法检测限为０．８１μｇ／ｍＬ甲硝唑和０．１６μｇ／ｍＬ维生素Ｂ６，二测定的线性范围均为１．６－２２．４μｇ／ｍＬ，直接用于复方甲硝唑片剂中甲硝唑和维生素Ｂ６的测定，两种生物的测定变异系数分别小于２．２６和２．６０％，回收率分别为９３－１０２％和９９－１０１％．     

Determination of trace iron (II) and molybdenum (VI) in ground water by pyrocatechol resin-phase spectrophotometry]

In weak acid medium (pH 6.20), Fe(III) and Mo(VI) can form colored complexes with pyrocatechol and quantitatively adsorbed on 717 strong base anion exchange resin. The apparent molar absorption coefficients of resin phase are epsilon = 4.1 x 10(4) L/(mol x cm) at 520 nm for Fe(III) and epsilon = 9.0 x 10(4) L/(mol x cm) at 400 nm for Mo(VI). Beer's law is obeyed for Fe (III) and Mo(VI) in the range of 0-2.2 mg x L(-1) and 0-1.6 mg x L(-1). The method has been applied to the determination of trace Fe(III) and Mo(VI) in ground water. The relative standard deviations are 3.3% and 3.2%, respectively.     

5‘—硝基水杨基荧光酮双波长标准加入分光光度法同时测定？…

在０．３－０．９ｍｏｌ／Ｌ硫酸介质中，在溴化十六烷基三甲铵存在下，５’－硝基水杨基荧光酮与锗和钼形成最大吸收波长分别为５１３和５３３ｎｍ的红色配合物，其吸收光谱严重重叠。基于此，本文采用双波长标准加入法对该混合物的显色体系进行了研究，建立了同时分光光度测定锗和钼的新方法，并与等吸收双波长法作了比较。     

催化动力学褪色光度法测定痕量铜（Ⅱ）的研究

研究了在盐酸介质中 ,铜 (Ⅱ )催化过氧化氢氧化孔雀绿褪色反应的适宜条件与影响因素 ,建立了催化动力学光度法测定痕量铜的新方法。该方法是用固定时间法在 6 15nm波长处监测催化反应。方法的线性范围为 0～ 2 2 μg·L- 1 ,检出限为 1 92× 10 - 9g·mL- 1 ,该催化反应对铜 (Ⅱ )为一级反应 ,表观活化能为12 2 3kJ·mol- 1 ,表观反应速率常数为 7 70× 10 - 4s- 1 。因为Fe3 干扰Cu(Ⅱ )的测定 ,用PO3-4与Fe3 生成稳定的 [Fe(PO4 ) 2 ]3- 络合物 ,可掩蔽Fe3 。方法相对标准偏差为 1 16 % ,标准加入回收率为 98 3%～10 0 3%。该方法用于水样品、茶叶样品、奶粉样品以及苹果样品中铜的测定 ,获满意结果     

The effect of aluminum overlayers on the magnetization of iron and iron-nickel alloys

Iron and iron-nickel films 2 to 10 nm thick were prepared in a high vacuum magnetometer. The magnetic moment of each iron or iron nickel film was measured in situ, then an aluminum overlayer (2–30 nm thick) was deposited on the ferromagnetic film, and the magnetic moment was again measured in situ. The aluminum overlayer decreases the magnetic moment as if the iron film or iron-nickel film thickness decreases by about 0.3 to 0.5 nm.     

A study of trinuclear iron(III) O-phthalates

Mössbauer data as well as infrared and magnetic susceptibility results indicate that Fe(III)-phthalates are high spin ferric complexes with a combination of trinuclear oxo-bridged and monomer structures. Values obtained for the isomer shift and quadrupole splitting parameters suggest that different counter ions, such as OH, NO₃, and Na, leave the Fe(III) ions in two very distorted octahedral arrangements, although they scarcely affect the electron densities at the iron nuclei.     

Heat capacity of a five-coordinated iron(III) complex,iodobis (N,N-Dimethyldithiocarbamato) iron(III), between 0.4 and 300 K

The heat capacity of iodobis (N, N-dimethyldithiocarbamato)iron(III) has been measured between 0.4 and 300 K. Based on the heat capacity and entropy at low temperatures it was found that the present sample consists of a mixture of monomer (ca. 40%) and dinier (ca. 60%); the former brings about a λ-type phase transition from an antiferromagnetic to a paramagnetic state at T_N = (1.65 ±0.04) K while the latter exhibits a Schottky-ype anomaly due to antiferromagnetic dimeric coupling, the effect of which becomes dominant below ca. 0.7 K. The zero-field splitting parameter of a single ferric ion was estimated to be $\text{D}\text{k}\text{=}\text{D}{}_{\mathrm{D}}\text{k}\text{= 14 K}$ for the monometer and the dimer, while the dimeric coupling constant was $\text{J}{}_{\mathrm{D}}\text{k}\text{= ?0.15 K}$. The entropy at low temperatures cannot be accounted for solely by the spin manifold. Additional contribution from a tunnel-splitting of the rotational levels of four constituent methyl-groups has been discussed. In this case, the level splitting of the ground state is 2.5 J mol^?1 and the barrier height of hindering potential is 2.3 kJ mol^?1.     

Reduction of iron(III) in annealed asbestos/chrysotile

Magnetic and structural properties of Bi substituted YIG with nominal formula of Bi _x Y_3???x Fe₅O₁₂ (x?=?0.0, 0.25, 0.5, 0.75, 1.00) prepared via Mechanochemical Processing (MCP) have been studied with Mossbauer spectroscopy, X-ray diffraction (XRD). The temperature dependence of sublattice magnetic hyperfine field for samples is analyzed. The a–d intersublattice superexchange found to be antiferromagnetic and increases from ??21.97 to ??25.79 k_B as Bi increases from 0.0 to 0.25. The a–a and d–d intrasublattice exchanges for sample x?=?0.0 are 13.18 and 10.55 k_B respectively while for sample x?=?0.25 a–a and d–d intrasublattice exchanges are 7.7 and 8.9 k_B respectively. The correlation of lattice constant and superexchange interaction are discussed.     

Formation of fractal structures by aggregation of anisometric iron (III) hydroxide particles

Coagulation of anisometric iron (III) hydroxide sols has been studied by dynamic light scattering, TEM and ultra-small-angle X-ray scattering. The anisometry of rod-like individual colloidal particles can be characterised with a mean aspect ratio of 10. It was established for the first time, that the aggregates formed by coagulation of anisometric particles show definite fractal structure with a mass fractal dimension of 1.95 ± 0.05.     

Magnetic properties of calcium-silicates (diopside and gehlenite) doped with iron (III)

The incorporation of Fe³⁺ cations into some Ca-silicates (diopside, gehlenite), substituting for alkali earths of different valencies and in differently coordinated lattice positions, will give rise to considerable lattice disorder. It is shown that this will result in special magnetization properties of these silicates.     

Spin-spin relaxation in heteropolynuclear clusters containing iron(III) and copper(II) ions

The magnetic coupling between Fe(III) and Cu(II) and the relaxation behavior of the spin centered at the iron have been studied in di- and trinuclear clusters. The experimental spectra have been analyzed in terms of a simple cross-relaxation model. In the strongly coupled trimer the relaxation rates are determined by a Boltzmann factor and a single field- and temperature-independent scaling parameter¹ w ₀, while the weakly coupled dimer exhibits obviously a more complex behavior.     

Measurements of degree of sensitization (DoS) in aluminum alloys using EMAT ultrasound

Sensitization in 5XXX aluminum alloys is an insidious problem characterized by the gradual formation and growth of beta phase (Mg₂Al₃) at grain boundaries, which increases the susceptibility of alloys to intergranular corrosion (IGC) and intergranular stress-corrosion cracking (IGSCC). The degree of sensitization (DoS) is currently quantified by the ASTM G67 Nitric Acid Mass Loss Test, which is destructive and time consuming. A fast, reliable, and non-destructive method for rapid detection and the assessment of the condition of DoS in AA5XXX aluminum alloys in the field is highly desirable. In this paper, we describe a non-destructive method for measurements of DoS in aluminum alloys with an electromagnetic acoustic transducer (EMAT). AA5083 aluminum alloy samples were sensitized at 100 °C with processing times varying from 7 days to 30 days. The DoS of sensitized samples was first quantified with the ASTM 67 test in the laboratory. Both ultrasonic velocity and attenuation in sensitized specimens were then measured using EMAT and the results were correlated with the DoS data. We found that the longitudinal wave velocity was almost a constant, independent of the sensitization, which suggests that the longitudinal wave can be used to determine the sample thickness. The shear wave velocity and especially the shear wave attenuation are sensitive to DoS. Relationships between DoS and the shear velocity, as well as the shear attenuation have been established. Finally, we performed the data mining to evaluate and improve the accuracy in the measurements of DoS in aluminum alloys with EMAT.     

Studies of magnetite nanoparticles synthesized by thermal decomposition of iron (III) acetylacetonate in tri(ethylene glycol)

In this paper, water-soluble magnetite nanoparticles have been directly synthesized by thermal decomposition of iron (III) acetylacetonate, Fe(acac)₃ in tri(ethyleneglycol). Size and morphology of the nanoparticles are determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements while the crystal structure is identified using X-ray diffraction (XRD). Surface charge and surface coating of the nanoparticles are recognized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS) and zeta potential measurements. Magnetic properties are determined using vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID) measurements. The results show that as-prepared magnetite nanoparticles are relatively monodisperse, single crystalline and superparamagnetic in nature with the blocking temperature at around 100 K. The magnetite nanoparticles are found to be highly soluble in water due to steric and electrostatic interactions between the particles arising by the surface adsorbed tri(ethyleneglycol) molecules and associated positive charges, respectively. Cytotoxicity studies on human cervical (SiHa), mouse melanoma (B16F10) and mouse primary fibroblast cells demonstrate that up to a dose of 80 μg/ml, the magnetic nanoparticles are nontoxic to the cells. Specific absorption rate (SAR) value has been calculated to be 885 and 539 W/gm for samples with the iron concentration of 1 and 0.5 mg/ml, respectively. The high SAR value upon exposure to 20 MHz radiofrequency signifies the applicability of as-prepared magnetite nanoparticles for a feasible magnetic hyperthermia treatment.