The determination of the Si and Ge content in SiGe alloy by gamma ray absorption spectroscopy

γ-Ray absorption spectroscopy has been used to accurately determine the Si and Ge content in SiGe alloys. This technique provides a fast, accurate, and non-destructive method for determining concentrations of components in binary systems. This work supported by the U. S. Atomic Energy Commission.     

基于中子活化瞬发伽马能谱确定地层元素含量的方法

中子技术能够利用中子与物质的相互作用确定其组成等性质,广泛应用于医学、环境科学、核反应堆建设、金属矿产勘查及石油工业中。在石油天然气领域,中子探测技术主要被用于确定井孔中的孔隙度、密度和流体饱和度等参数。随着测井技术的不断发展,基于瞬发伽马射线的中子活化分析技术也已应用于井下确定地层元素含量,并成为复杂岩性和非常规油气储层获得矿物含量的唯一手段。本文阐述了地层元素伽马能谱测井的方法,利用蒙特卡罗方法模拟了不同地层条件下的伽马能谱,构建了地层元素的标准谱库,研究了奇异值分解和极大似然估计能谱数据处理方法,并利用得到的元素产额及氧闭合模型实现地层元素含量的确定。利用蒙特卡罗方法构建已知地层的伽马能谱,采用上述数据处理方法得到元素含量与地层真实元素含量误差均在4%之内,Si元素误差最大为2.8%,Ca元素最大误差为3.3%,研究结果为井下确定地层元素成分及含量提供了有效的技术支持。     

人工神经网络法同时测定苯二酚异构体

研究了人工神经网络法与紫外分光光度分析相结合，用于邻苯二酚、间苯二酚、对苯二酚异构体的含量测定。本研究采用人工神经网络法，直接对苯二酚异构体混合液的紫外吸收光谱数据进行预测，不需预先分离，即可得到各异构体的浓度。     

The determination of polyethylene glycol in gamma globulin solutions

Polyethylene glycol is determined in gamma globulin solution by treating the supernatant of the precipitated protein with barium and iodine forming a barium-iodide complex of the glycol which gives a band at 535 nm.     

A new gamma spectral analysis algorithm for the determination

The aim of the investigation was to determine whether the ¹³⁷Cs contamination found in plants around the Paks Nuclear Power Plant in Paks, Hungary was a result of local emission or of the earlier Chernobyl accident. We distinguished between the two possibilities on the basis of the ¹³⁴Cs/¹³⁷Cs ratio. The ¹³⁴Cs activities to be measured were extremely low, in some cases undetectable with conventional evaluation softwares. Therefore a special algorithm was used to determine the ¹³⁴Cs/¹³⁷Cs ratio. On the basis of the results it is evident, that the contamination originated from Chernobyl.     

Determination of the water content of foods : Indirect determination of the water content

The indirect determination of the water content of foods is dealt witli on the basis of tlie following general considerations: A. The absolute vapour pressure of the water in the substance to be desiccated ; B. The absolute vapour pressure of the water in the surrounding air, C. Behaviour of the non-water components of the substance to be desicented , D. Special causes of errors, viz.: 1.. Retardation in the establishment of equihbrium; 2. Retardation due to title structure of the substancc to be desiccated, 3. Crust formation; 4. Analytical errors. E. Rate of desiccation: reference methods and rapid routine methods.We prefer to consider the problems relating to the indirect determination of the water content on the basis of absolute water vapour pressures. The advantages and disadvantages of this method of treatment have been indicated.     

刚果红光度法测定西索米星的含量

西索米星(sisom icin,SISO)是新一代广谱氨基糖苷类抗生素,在临床上广泛应用。目前测定西索米星的方法主要有微生物法[1]和高效液相色谱法[2-6],对其它氨基糖苷药物的测定有衍生化法[7,8]。本文利用酸性染料刚果红与西索米星在一定的条件下生成红色离子缔合物,使刚果红溶液褪色,建立了测定西索米星的褪色分光光度法。在pH4·5~6·8范围内,西索米星与刚果红生成的缔合物最大褪色波长为504nm,表观摩尔吸光系数为2·31×104L·mol-1·cm-1,西索米星在0·10mg/L~6·72mg/L浓度范围内,遵从比尔定律。可用于市售硫酸西索米星药物、人体尿液及…     

Direct determination of the phenanthrene and methylphenanthrene isomer distribution in crude oils by multidimensional capillary GC

The methylphenanthrene index (MPI) [1,2] which was recognized as suitable for the assessment of the “thermal” history of sedimentary organic matter, can be determined directly i.e. without preceding LC group separations by application of multi-dimensional GC in capillary columns. A GC double oven instrument (Siemens Sichromat 2) equipped with a “live switching” coupling piece was used for the necessary measurements.     

Reduction of the 2,4,6-trichloroanisole content in cork stoppers using gamma radiation

This work demonstrates that it is possible to eliminate or transform 2,4,6-trichloroanisole (2,4,6-TCA) in cork stoppers, using gamma radiation transforming it in molecular residues which do not have the same organoleptic/odour characteristics. This process when applied to packed cork stoppers ready to use, inside their sealed packages, avoiding later contamination, assures the elimination/reduction of the problem, which is an enormous advantage over the other processes. Studies were carried out with cork stoppers naturally contaminated using radiation doses from 15 to 400 kGy. The results showed elimination/reduction efficiencies of 2,4,6-TCA higher than 90%.     

The use of thermal analysis in the approximate determination of the cement content in concrete

Thermal analysis was first used to investigate the pattern of dissociation of hydrated ordinary Portland cement. Portlandite (Ca(OH)₂) decomposes at about 500°C. This was confirmed by kinetic calculations. Thermal analysis was then performed to establish the effect of varying the cement content on the percent mass loss associated with the decomposition of Ca(OH)₂ in cement mortar cured for 28 days. An increasing relation was obtained. Standard concrete cubes were then prepared with cement contents ranging from 200 to 450 kg m^-3. The loss in mass on heating, up to 750°C, of concrete samples cured for 28 days was then related to the cement content in concrete. The relation obtained was tested for concrete cubes of known cement content and found to be in better agreement than the results obtained by conventional chemical analysis. This method can be used for an approximate determination of the cement content in concrete. This revised version was published online in July 2006 with corrections to the Cover Date.     

The determination of the Fe content in natural sphalerites by means of Raman spectroscopy

Natural sphalerite samples collected from the Baia Sprie ore deposit (Romania) were analyzed through Raman spectroscopy, SEM-EDX and XRD. The most intense Raman lines at 300, 331 and 350 cm⁻¹ were used to improve iron determination method from sphalerites by Raman spectroscopy. It is well known that the iron content of synthetic sphalerite can be quantified by measuring the height of Raman lines (h₁, h₃). By using the new h₂/h₃ and (h₁ + h₂)/h₃ ratios and two additional linear equations, this method is improved and becomes suitable to natural sphalerites. The results are in good agreement with the SEM-EDX data.     

DTA determination of the anhydrite content in rock salts

The DTA method was used to determine the phase diagram of the NaCl-CaSO₄ system over the range 0.55 wt.% of CaSO₄ in air atmosphere. The effects of SiO₂, CaCO₃ and Fe₂O₃ on the melting temperatures of pure NaCl and the eutectic were determined. On the basis of the above temperatures, a method of quantitative determination of the anhydrite content in rock salts has been developed.

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Zusammenfassung DTA wurde benutzt, um in Luft im Bereich 0 bis 55,0 Gew.% CaSO₄ das Phasendiagramm des Systemes NaCl-CaSO₄ zu bestimmen. Es wurde auch der Einfluß von SiO₂, CaCO₃ und Fe₂O₃ auf die Schmelztemperatur von reinem NaCl bzw. des Eutektikums bestimmt. Auf der Grundlage obiger Temperaturen wurde eine Methode zur quantitativen Bestimmung des Anhydritgehaltes in Steinsalzen entwickelt.

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Errors occurring in the determination of temperature-heat content curves

In the determination of temperature-heat content curves errors may occur which are due to low transition rates, low diffusion rates and low rates of heat transfer. These errors are subsequently discussed. Liquid to solid transitions may be slow even when liquid and solid are in contact with each other at finite ratios. This causes appreciable differences between melting temperatures and solidification temperatures. The phenomenon is called two-phase undercooling. When two-phase undercooling occurs the cooling curve obtained may lead to erroneous conclusions, e.g. an impure substance may seem to be extremely pure. This is illustrated by experiments.As far as is known two-phase superheating appears to be negligible under normal conditions. Therefore heating curves are preferred to cooling curves.As stirring cannot promote diffusion in the solid phase it is doubted whether the stirrer method has advantages over the thin film method.Errors due to limited heat transfer and occurring with the thin film method have been calculated. Formulae have been given relating the dimensions of a thin film apparatus and the rate of heating to the accuracy aimed at.Application of an internal check on heating curves is recommended.     

The influence of gamma irradiation on flavonoïds content during storage of irradiated clementina

The influence of Gamma irradiation on content of some important flavonoïds (flavonones glycosides and polymethoxylated flavones) was evaluated during storage of Moroccan clementina treated at a mean dose of 0.3 kGy and stored three months at 3′C. Results shows that at day one, gamma irradiation induced degradation of small quantities of these flavonoïds, however after 14 days of storage, the content of these compounds was significantly higher (p≤0.05) in irradiated samples. Irradiation stimulated biosynthesis of flavonoïds after 14 days of storage. Hesperidin was the major flavanones compounds in clementines. Nobiletin and Heptamethoxyflavone were the major polymethoxylated flavones in clementines. Our study demonstrated that the content of these compounds was significantly higher (p≤0.05) in irradiated samples.