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排序方式: 共有390条查询结果,搜索用时 244 毫秒
1.
Bahraminasab A. Tabei S. M. A. Masoudi A. A. Shahbazi F. Reza Rahimi Tabar M. 《Journal of statistical physics》2004,116(5-6):1521-1544
The joint probability distribution function (PDF) of the height and its gradients is derived for a zero tension d + 1-dimensional Kardar-Parisi-Zhang (KPZ) equation. It is proved that the height's PDF of zero tension KPZ equation shows lack of positivity after a finite time t c . The properties of zero tension KPZ equation and its differences with the case that it possess an infinitesimal surface tension is discussed. Also potential relation between the time scale t c and the singularity time scale t c.v→0 of the KPZ equation with an infinitesimal surface tension is investigated. 相似文献
2.
A. Gharib H. Rahimi H. Pyrovan N. J. Raoffi H. Taherpoor 《Journal of Radioanalytical and Nuclear Chemistry》1985,89(1):31-44
This work is part of a project with the IAEA, in a coordinated program on Trace Elements in Human and Bio-Environmental Systems to evaluate their nutritional requirements, interrelations and the role of trace elements in health, metabolism, etc. Cow's milk being regarded as one of the most important and nutritious foodstuffs consumed by people. Hence as a first step, an elemental analysis for milk was carried out for this purpose; a few samples of pasteurized milk and local sample were investigated for essential and toxic trace elements. The secondary aim of this project was the assessment of various analytical techniques involved. However, in the present work, the methods involved were AAS, PIXE and NAA. The latter method was applied both instrumentally and radiochemically. Although the results pertaining to the various methods employed are not in good agreement. there is, however, some justification to clarify this internal inconsistency. The precision of NAA and AAS allows a greater degree of acceptance. Although PIXE is very fast and rather routine, the technique for trace element analysis needs certain adaptations and development. 相似文献
3.
The potentiometric response properties and applications of a tetra-coordinate nickel(II) complex with relatively high selectivity toward nitrate ion are described. The nickel(II) complex of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,13-tetraene was used as a neutral carrier into plasticized poly(vinyl chloride) (PVC) membrane. The influence of several variables was investigated in order to optimize the potentiometric response and selectivity of the electrode. The resulting membrane electrode incorporating 31.0% PVC, 61.0% dioctyl phthalate (DOP) as plasticizer, 3% methyltrioctylammonium chloride (MTOAC) as a cationic additive and 5% carrier (all w/w) demonstrates a Nernstian response slope of −59.6 mV per decade over the concentration range of 5×10−6-1×10−1 M NO3−. The electrode exhibits a fast response time (≤10 s), a detection limit of 2.5×10−6 M, and can be used over a wide pH range of 4-12. The electrode shows improved selectivity in comparison to most of the previously reported nitrate-selective electrodes. It was successfully applied to the determination of nitrate ion in natural water samples. 相似文献
4.
Flameless atomic absorption techniques were used to determine the lead and other atmospheric particulate in the city of Tehran. 640 samples were collected in 20 different stations around the city during four seasons in 1992. The radioactivity of the air samples was also measured by -ray spectrometry using high purity Ge/Li detectors, and a multichannel analyzer. The results were compared with previous measurements in the city of Tehran. 相似文献
5.
Radiotracer method was developed for measuring14CO2 content in cement-wood mixtures. The carbon dioxide used for the treatment was labeled with14C, a -emitting radioisotope, and samples were measured by -scintillation and liquid scintillation techniques. Test samples were prepared in the laboratory with various compositions and treated with labeled14CO2. The tracer was released from Ba14CO3 by lactic acid with total activity of 37 MBq. Selectivity of the technique allows to distinguish the carbon dioxide bound during the treatment and bound previously from the mbient air. Sensitivity of the method is higher than that of traditional methods and allowed determination of CO2 content in each component of the mixture. It is 63 ng. if measured by -scintillation detector and 1.6 ng, if measured by liquid scintillation. Accuracy of the method is 0.3%. 相似文献
6.
Polyphosphazenes form one of the most important and interesting classes of inorganic polymers having a backbone of alternating
phosphorus and nitrogen atoms with phosphorus atom bearing two organic side groups. The most important feature of these polymers
is the synthesis route which allows the side groups to be changed over a wide range to obtain a broad variety of products
with different properties from elastomers to glasses, water soluble to hydrophobic polymers, bioinert to bioactive materials,
and electrical insulators to conductors. In this paper, some novel applications of these polymers in biomedical materials
and advanced devices are reviewed. 相似文献
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Green and one‐pot surface coating of iron oxide magnetic nanoparticles with natural amino acids and biocompatibility investigation 下载免费PDF全文
Hamed Nosrati Marziyeh Salehiabar Elahe Attari Soodabeh Davaran Hossein Danafar Hamidreza Kheiri Manjili 《应用有机金属化学》2018,32(2)
We report the synthesis of iron oxide magnetic nanoparticles (IONPs) coated with various natural amino acids (AAs) using a one‐pot reaction in an aqueous medium. Several AAs, which contained hydrophilic and hydrophobic groups, were selected to study their effects on size, morphology and toxicity of IONPs. Functionalized IONPs were characterized using X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopies. Furthermore, vibrating sample magnetometry analysis shows these nanoparticles have excellent magnetic properties. Cellular toxicity of IONPs was also investigated on HFF2 cell lines. The AA‐coated IONPs are non‐toxic and biocompatible. Natural AA‐coated IONPs show a potential for their development in in vitro and in vivo biomedical fields due to their non‐toxicity, good ζ‐potential and related small size and narrow size distribution. 相似文献
10.
Multistage stochastic programming (SP) with both endogenous and exogenous uncertainties is a novel problem in which some uncertain parameters are decision-dependent and others are independent of decisions. The main difficulty of this problem is that nonanticipativity constraints (NACs) make up a significantly large constraint set, growing very fast with the number of scenarios and leading to an intractable model. Usually, a lot of these constraints are redundant and hence, identification and elimination of redundant NACs can cause a significant reduction in the problem size. Recently, a polynomial time algorithm has been proposed in the literature which is able to identify all redundant NACs in an SP problem with only endogenous uncertainty. In this paper, however, we extend the algorithm proposed in the literature and present a new method which is able to make the upper most possible reduction in the number of NACs in any SP with both exogenous and endogenous uncertain parameters. Proving the validity of this method is another innovation of this study. Computational results confirm that the proposed approach can significantly reduce the problem size within a reasonable computation time. 相似文献