首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
In a population sample of residents of Novosibirsk between the ages of 45 and 69, the complex of the following chemical components of blood is determined by SR XRF: K, Ca, Fe, Cu, Zn, Ge, Se, Br, Rb, Sr, Zr, and Pb. Risk factors of chronic noncommunicable diseases are determined: obesity, arterial hypertension, dislipidemia, and their associations with chemical elements Ca, Cu, Rb, Y, and Pb.  相似文献   

2.
The surface composition of AgSn alloys with low Cu and Zn contents was investigated by ESCA following various pretreatments. Exposure to air, especially at elevated temperatures, resulted in the surface being enriched, not only by Sn, but particularly by the Zn and Cu contents in the form of oxides. Zn and Cu enrichment is less pronounced when heating in a vacuum (10?6 Torr). Any tin oxide present is partially reduced. The results obtained are compared with model concepts established by various authors from studies of binary alloys.  相似文献   

3.
Carbon micro- and nanoscale structures formed during the consolidation of magmatic rocks is investigated. They are very similar to nanoscale carbon structures synthesized in a laboratory. A wide range of elements (Fe, K, Ti, V, Cr, Mn, Ni, Pt, Zn, Ga, Ge, Br, Sr, Zr, and Pb) are identified by XRF analysis in natural globules of graphite containing micro- and nanoscale structures. Some of these elements are thought to be natural catalysts in the formation of carbon structures by chemical vapor phase deposition (CCVD); the rest (rare-earth and noble metals) are considered to be useful as indicators of host rock mineralization.  相似文献   

4.
A S Divatia 《Pramana》1989,32(4):591-598
Trace elements in various materials using nuclear techniques are studied. Results obtained by using energy-dispersive X-ray fluorescence (EDXRF) and proton-induced X-ray emission (PIXE) are examined. The EDXRF method is used to quantitatively evaluate trace elements such as Mn, Fe, Cu, Zn, Br, Rb and Sr in tea leaves. Correlation of trace elements in tea leaves and in the corresponding soil is studied.  相似文献   

5.
Environmental studies have revealed significant contributions of vehicular exhaust emissions to high pollution levels in urban dwellings. The levels and sources of heavy metal contaminations of some major roads in Accra have been investigated in this work. Street dust samples collected from four major roads in Accra (Mallam Junction‐Weija road, John Teye‐Pokuase road, Tema Motorway and Tetteh Quarshie Interchange in Accra) were analysed for their elemental concentrations using energy‐dispersive X‐ray fluorescence. Twenty elements were identified: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr and Pb. Significant concentration levels were obtained for K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Br, Rb, Sr, Y, Zr and Pb in all the samples and were used for the source identification. Enrichment factors and principal component analysis were used to verify the anthropogenic contribution to road dust. Results obtained for the enrichment factors showed moderate enrichment for V, Cr and Cu, while Zn, Br, Zr and Pb were significantly enriched. Principal component analysis identified four sources and their contributions to the elemental contents in the road dust. Natural crust, brake wear, tyre wear and vehicle exhaust emission were the four sources identified. The contribution of vehicular non‐exhaust emissions to heavy metal contamination in the road dust was found to be greater than that of exhaust emissions. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

6.
《X射线光谱测定》2006,35(4):253-256
A large body of evidence indicates that abnormalities in the levels of iron, copper and zinc and their metabolism are associated with neurodegenerative diseases. However, it is difficult to decide whether any observed changes of trace elements reflect the primary disease process or are secondary to a primary process or mechanism. In the present study, Fe, Cu and Zn in organs of transgenic mice which express the familial Alzheimer's disease (AD) gene and normal mice of the same species and ages were determined by X‐ray fluorescence (XRF) spectrometry. The results show that Fe concentrations in a variety of organs and tissues were significantly increased whereas Zn concentrations decreased in the transgenic mice as compared with the ‘normals’. The levels of Cu in transgenic mice were also altered. Data obtained in the present study suggest that expression of the familial AD gene in mice results in altered homeostasis of Fe, Cu and Zn in organs of the animals, which may in turn accelerate the process of neurodegeneration. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

7.
Synchrotron radiation based x-ray fluorescence (SRXRF) was applied to the quantitative evaluation of elemental changes in substantia nigra pars compacta (SNc) in Parkinson's disease (PD) in the framework of a study on the role of chemical elements in the pathophysiology of PD. The analysis was carried out for dopaminergic nerve cells and extraneuronal spaces. The mass fractions of P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb were determined. The application of standard samples developed especially for the determination of elemental mass fractions in thin tissue sections using the SRXRF technique is presented. Two-dimensional maps of elemental distribution show that the location of nerve cells in SNc sections is precisely visualized by the high levels of most elements. It was found that statistically significant differences between control and PD neurons are observed for S (p = 0.04), Cl (p = 0.02), Ca (p = 0.08), Fe (p = 0.04) and Zn (p = 0.04). The mass fractions of P (p = 0.08), S (p = 0.07), Cl (p = 0.04), Zn (p = 0.08) and Rb (p = 0.08) in areas outside the nerve cell bodies differed significantly between PD and control groups. A clear cluster separation between the PD nerve cells and neurons representing the control group was noticed. It was found that Cl, Fe, Ca and Zn are the most significant elements in the general discrimination between PD nerve cells and the control. The comparison between the extraneuronal spaces showed that Cl, Fe and Cu differentiate the PD and control group the most. The evident contribution of chemical elements to the pathophysiology of PD was shown.  相似文献   

8.
The high-resolution 93.3-keV Mössbauer resonance in67Zn was used to investigate Cu?Zn alloys (brass) containing 16.6 wt.% Zn (α-phase) and 50.5 wt.% Zn (β'-phase) at pressures up to 6.2 GPa and at 4.2 K. The recoil-free fraction and the center shift change linearly with reduced volume. The decrease of the center shift is due to the second-order Doppler effect which is partially compensated by the increase of the s-electron density at the67Zn nucleus when the conduction electrons are compressed. In α-brass short-range order leads to four different Cu?Zn configurations. One of them exhibits a center shift which nearly coincides with that of the β'-phase.  相似文献   

9.
The aim of the present work is to examine if the Hume-Rothery stabilisation mechanism holds across whole solid solution ranges in a series of gamma-brasses with especial attention to the role of vacancies introduced into the large unit cell. The concentration dependence of the number of atoms in the unit cell, N, for gamma-brasses in the Cu–Zn, Cu–Cd, Cu–Al, Cu–Ga, Ni–Zn and Co–Zn alloy systems was determined by measuring the density and lattice constants at room temperature. The number of itinerant electrons in the unit cell, e/uc, is evaluated by taking a product of N and the number of itinerant electrons per atom, e/a, for the transition metal element deduced earlier from the full-potential linearised augmented plane wave (FLAPW)-Fourier analysis. The results are discussed within the rigid-band model using as a host the density of states (DOS) derived earlier from the FLAPW band calculations for the stoichiometric gamma-brasses Cu5Zn8, Cu9Al4 and TM2Zn11 (TM = Co and Ni). A solid solution range of gamma-brasses in Cu–Zn, Cu–Cd, Cu–Al, Cu–Ga and Ni–Zn alloy systems is found to fall inside the existing pseudogap at the Fermi level. This is taken as confirmation of the validity of the Hume-Rothery stability mechanism for a whole solute concentration range of these gamma-brasses. An exception to this behaviour was found in the Co–Zn gamma-brasses, where orbital hybridisation effects are claimed to play a crucial role in stabilisation.  相似文献   

10.
密封消解ICP-AES和ICP-MS测定中日两国茶叶中23种矿质元素   总被引:18,自引:4,他引:14  
收集了13种中国茶叶和6种日本茶叶,在进行密封消解后,采用电感耦合等离子体发射光谱法(ICP-AES)和电感耦合等离子体质谱法(ICP-MS)测定了茶叶中Al,Ba,Ca,Cd,Ce,Co,Cr,Cs,Cu,Fe,La,Mg,Mn,Na,Ni,Pb,Rb,Sb,Sr,Th,U,Y和Zn等23种矿质元素的含量,并用茶叶标准参考物质(GBW07605)评价了分析方法的准确度。研究结果表明:密封消解有助于获得较为准确的茶叶中矿质元素含量的分析结果;与日本茶叶相比,中国茶叶中Cd,Co,Cr,Cs,Fe,Pb,Rb,Sb,Th,U和Zn等元素含量显著偏高(P<0.05),预示大气重金属污染程度中国较日本严重。另外,还发现茶叶中一些矿质元素含量之间有很强的线性相关性。  相似文献   

11.
Concentrations of K, Ca, Cr, Fe, Ni, Cu, Zn, Se, Rb, Sr, Cd, Hg and Pb were measured in the muscle, digestive glands and gonads of Octopus vulgaris, Lolligo vulgaris and Sepia officinalis captured in the west and south coast of Portugal. Essential elements (K, Ca, Fe, Cu, Zn, Se, Rb and Sr) were obtained by energy dispersive x‐ray fluorescence spectrometry, while toxic elements (Cr, Ni, Cd, Hg and Pb) were obtained by atomic absorption spectrometry. The latter technique was used owing to its higher sensitivity, since these elements were not detected by the first technique. The tissues of the three species present a similar pattern for essential elements. Potassium and Ca are present at the highest concentration in all the studied samples. The highest levels for toxic elements were found in the digestive glands, exceeding the maximum allowed values in the case of Se and Cd. However, in the muscle tissue these values were never reached. Comparing both coasts, we can say that the west coast presents higher levels of Pb while the south coast presents enhanced levels of Hg. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

12.
Twelve lichen species growing on different ecological habitats in East Antarctica were analyzed for Cr, Cu, Fe, Pb and Zn. All the species had consistently higher amounts of Fe and Cu, as their substrata were iron and copper mineralized rocks. the foliose and fruticose lichens had a greater concentration of heavy metals than the crustose ones. Significantly, lead was not detected in any sample indicating that the area is still free from pollution.  相似文献   

13.
We report on the use of elemental composition, determined by energy dispersive X-ray fluorescence (EDXRF), to identify different types of paper. The concentrations of S, Cl, K, Ca, Ti, Mn, Fe, Co, Cu, Zn, As, Br, Rb, Sr, Ba and Pb were determined in papers from 1555, 1575, 1724, 1748, 1779, 1782, 1787, 1806, 1861, 1919, 1941 and 2005. A preliminary analysis was made with the use of a dendrogram. The Euclidian distances evidenced a big fluctuation in the elemental composition on most recent papers. The dendrogram also allowed us to catalogue the analysed samples into ten types of paper. Calcium, Cu, Fe, Zn and Sr were the only elements found in all paper samples. However the content of each element was different in every paper type. Calcium is the predominant element in all paper types. Applying Spearman coefficients correlations to these papers for Ca, Cu, Fe, Zn and Sr, we found moderate negative correlations between Ca-Cu. Positive correlations were also found between Fe-Cu, though not very strong. High levels of the toxic elements, Co, Ni, As and Pb were present in papers from 1779 and 1787. From this work it becomes clear that the number of elements in modern papers is lower than in older ones. PACS 39.30.+W; 78.70.En; 89.90.+n  相似文献   

14.
《Surface science》1991,255(3):L557-L561
Synchrotron radiation photoelectron spectra taken at 100 eV photon energy have been measured to characterize the interface reactions of the metal-insulator-semiconductor systems Cu/RbF/GaAs(100) and Cu/RbF/Ge(100). In comparision, similar sequences are studied on the Cu/GaAs(100) and Cu/Ge(100) interfaces without the RbF interlayer. After Cu-deposition of 1–4 Å on RbF-covered (10–14 Å) GaAs and Ge surfaces, shoulder peaks appear on both the Ga 3d and Ge 3d core levels. The shoulder peaks are shifted 1.1 and 1.4 eV to higher binding energy for the Ga 3d and Ge 3d levels, respectively. The Rb 4p and F 2p peak positions are slightly shifted between 0.25 and 0.5 eV. The broad second Ga 3d and Ge 3d peaks can be correlated to plasmon loss of electrons from these levels in a two-dimensional Rb metal-like layer formed at the Cu/RbF interface. The excitation energy of a Rb surface plasmon in a Cu-Rb-RbF system is calculated to be 1.3 eV.  相似文献   

15.
SR scanning XRF is used to analyze the annual elemental layers of bottom sediments from Lake Teletskoye. Scanning is conducted with a pitch of 0.1 mm at energies of 16, 24, and 38 keV. The content of more than 15 elements are determined: K, Ca, Ti, Mn, Fe, V, Cr, Ni, Cu, Zn, As, Rb, Sr, Y, Zr, Cd, Sn, I, and Ba (range of concentrations, 0.005–10%). A cross section containing (1) the upper part of an underlying layer, (2) the total annual layer, (3) one more complete layer, and (4) the lower part of an overlapping layer is measured. Geochemical indicators reflecting the rhythm of annual precipitation are found.  相似文献   

16.
采用SPECTROSCAN-U型便携式波长色散X射线荧光光谱仪,使用粉末样品压片制样,现场分析了某铜矿区样品中的Cu、Pb、Zn、Co、Ni、Cr、V、Ti、Mn、Rb、Sr、Zr、Y、Ca、Fe等15种元素,获得了较好的精密度与准确度。用现场分析数据圈出的异常图与室内化学分析数据圈出的异常图符合较好,为野外现场快速分析作了有益的尝试。  相似文献   

17.
A general method to include temperature effects into the equation of state (EOS) of solids is discussed. A universal model based on a pseudo-spinodal approach is used to predict the pressure and temperature dependencies of the thermodynamic properties for a variety of solids: n-H2, Ar, Kr, Xe, NaCl, LiF, NaF, KCl, CsCl, Li, Na, K, Rb, Cs, Al, Fe, Cu, Zn, Ag, Cd, Pt, Au, and Pb. The predictive capabilities of the complete EOS are discussed and compared with available models.  相似文献   

18.
X射线荧光光谱压片法测定六种花瓣粉末的成分   总被引:1,自引:0,他引:1  
利用X射线荧光光谱法对白玫瑰花、红玫瑰花,白康乃馨、红康乃馨,白蝴蝶兰、红蝴蝶兰3个品种6个粉末样品中元素的种类和含量进行测定,并就每组样品的测定结果进行分析比对。结果表明,3个品种的花瓣粉末中均未检测出有毒元素的存在,且花瓣粉末中元素含量丰富;除含有常量元素外,还含有如Fe,Cu,Zn,Mn,Ni,Si,Sr,Rb等多种微量元素,但3个品种的微量元素的种类及含量有所差异;同一品种的花瓣粉末中元素的种类大致相同,而元素含量却各有差异,白色比红色中元素含量高。  相似文献   

19.
The content of micro- and macroelements was investigated in two algal species from the Bulgarian Black Sea aquatoria.

The radiochemical variant of neutron-activation analysis is used for elimination of the harmful activities of the macro-components 24Na, 42K, 32P, which makes it possible to determine 56Mn, 64Cu, 76As.

The quantitative composition of the elements Fc, Co, Cr, Cd, Sc, Zn, Ce, Sc, Rb, Au, Sm, As, Cu, Mn, Sb, Hg was measured.  相似文献   

20.
The level scheme of78Kr has been studied with the techniques of γ ray spectroscopy: decay spectra of78Rb produced by the reactions64Zn(16O,pn) and65Cu(16O,3n) have been measured; in-beam γγ coincidences have been taken during the irradiation of64Zn with16O ions; and an angular distribution measurement of γ rays from the reaction64Ni(16O, 2n)78Kr has been performed. Fifteen excited states in78Kr have been observed and spins have been proposed for most of these levels. A78Rb decay with a half-life of 17.5 ± 2 min has been found in addition to the previously known 6.0 ±0.2 min decay.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号