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101.
Harrison SM Kaml I Prokoratova V Mazanek M Kenndler E 《Analytical and bioanalytical chemistry》2005,382(7):1520-1526
Animal glues were often used in historic and artistic objects, e.g. as paint ground, as binders for pigments, or as adhesives. The sources were egg, casein, or different collagens. For restoration and conservation purposes it is important to know which kind of animal glue a museum object contains. Capillary electrophoresis can deliver such information, because it enables differentiation among the three proteinaceous glue classes according to their different amino acid patterns after hydrolysis. This work deals with the most relevant problem in practice, whether this identification is obstructed by the presence of other binders, with which they are mixed in many real samples; in particular, interference from plant gums and drying oils was investigated. Capillary electrophoresis of the hydrolysates (after reaction with 6 mol L–1 HCl) was performed with an acidic background electrolyte consisting of chloroacetic acid (51.9 mmol L–1) adjusted with LiOH to pH 2.26. The underivatised analytes were detected with a contactless conductivity detector. It was found that the constituents of the plant gums (monosaccharides) or drying oils (long-chain fatty acids and short-chain dicarboxylic acids) never interfered with identification of the animal glues, as shown for artificial mixtures of the different binders even at tenfold excess over the animal glue, and for egg tempera samples. The method was used to identify the filling material from a statue from the eighteenth century. 相似文献
102.
Enrico Aiello Gaetano Dattolo Girolamo Cirrincione Anna Maria Almerico Isabella D'Asdia 《Journal of heterocyclic chemistry》1981,18(6):1153-1155
The synthesis of a new heterocyclic ring system is described. Condensation of 1,4-diketones 1a,b with β-alanine gave the substituted propionic acids 2a,b which upon reduction with palladium on charcoal afforded compounds 3a,b . Title compounds 4a,b were obtained by refluxing 3a,b in toluene with p-toluenesulphonic acid as catalyst. 相似文献
103.
Maurizio Galimberti Nicoletta Mascellani Fabrizio Piemontesi Isabella Camurati 《Macromolecular rapid communications》1999,20(4):214-218
Ethene/propene copolymerizations were performed in solution with a single centre catalyst system composed of a “constrained geometry” half‐sandwich organometallic complex {η1: η5‐[(tert‐butylamido)dimethylsilyl](2,3,4,5‐tetramethyl‐1‐cyclopentadienyl)}titanium dichloride, and methylaluminoxane. The statistical treatment of polymerization data allowed to determine the reactivity ratios for ethene and propene: rE = 1.35 ± 0.09, rP = 0.82 ± 0.05, rErP = 1.10 ± 0.14. This catalyst system promotes an almost random distribution of ethene and propene and gives rise to values of rP and rE very similar to each other. 相似文献
104.
The location of path-shaped facilities on trees has been receiving a growing attention in the specialized literature in the recent years. Examples of such facilities include railroad lines, highways and public transit lines. Most of the papers deal with the problem of locating a path on a tree by minimizing either the maximum distance from the vertices of the tree to the facility or of minimizing the sum of the distances from all the vertices of the tree to the path. However, neither of the two above criteria alone capture all essential elements of a location problem. The sum of the distances criterion alone may result in solutions which are unacceptable from the point of view of the service level for the clients who are located far away from the facilities. On the other hand, the criterion of the minimization of the maximum distance, if used alone, may lead to very costly service systems. In the literature, there is just one paper that considers the problem of finding an optimal location of a path on a tree using combinations of the two above criteria, and efficient algorithms are provided. In particular, the cases where one criterion is optimized subject to a restriction on the value of the other are considered and linear time algorithms are presented. However, these problems do not consider any bound on the length or cost of the facility. In this paper we consider the two following problems: find a path which minimizes the sum of the distances such that the maximum distance from the vertices of the tree to the path is bounded by a fixed constant and such that the length of the path is not greater than a fixed value; find a path which minimizes the maximum distance with the sum of the distances being not greater than a fixed value and with bounded length. From an application point of view the constraint on the length of the path may refer to a budget constraint for establishing the facility. The restriction on the length of the path complicates the two problems but for both of them we give O(n log2 n) divide-and-conquer algorithms. 相似文献
105.
Daniela?IchimEmail author Ilaria?Peroni Fernando?Sparasci 《Journal of Mathematical Modelling and Algorithms》2005,4(3):253-264
In a linear regression framework, structural change models are proposed for the detection of abrupt changes in parameter values.
Two models are discussed: 1) the pure structural change model, where all the components of the parameter are allowed to change and are tested all together, and 2) the partial structural change model, where only some of the parameter
β components might change. For an on-line implementation, a sliding window algorithm is introduced. The procedure was successfully
applied to phase transition identification in cryogenic thermometry.
*Work partially funded under EU SofTools_MetroNet Contact N. G6RT-CT-2001-05061. 相似文献
106.
Isabella G Bashmakova 《Historia Mathematica》1981,8(4):393-416
This article contains an analysis of the methods for solving diophantine equations of second and third degrees in two unknowns, from the most ancient times to Poincaré. Special attention is paid to the works of Fermat, Euler, and Jacobi. 相似文献
107.
The work presented herein regards the analysis of an experimental technique for the execution of dynamic tensile tests on
structural material sheet specimens. Dynamic tensile testing of sheet is becoming more important due to the need for more
optimized vehicle crashworthiness analysis in the automotive industry. Positive strain-rate sensitivity, i.e. the strength
increases with strain-rate, offers a potential for improved energy absorption during a crash event.
Tests have been carried out in the Reliability and Safety Laboratory of the 2nd Engineering Faculty of the Politecnico di Torino. Different types of testing techniques have been used to generate data under
dynamic conditions. However, no guidelines are available for the testing method, specimen dimensions, measurement devices,
and other important issues which are critical for the quality of the results. Accurate signal processing and curve smoothing
are often necessary to make the testing data usable. 相似文献
108.
We discuss the possibility of discriminating between different supersymmetric see-saw models by improving the experimental sensitivity to charged lepton flavour violating processes. Assuming a hierarchical neutrino mass spectrum, we classify see-saw models according to how the hierarchy Δm2Δm2atm is generated, and study the predictions of each class for the branching ratios of τ→μγ and μ→eγ. The process τ→μγ is found to be a particularly promising tool to probe the fundamental see-saw parameters, and especially to identify the origin of the large atmospheric mixing angle. Predictions for μ→eγ are more model-dependent. We point out that, even with an improvement of the experimental sensitivities by three orders of magnitude, both τ→μγ and μ→eγ could escape detection in models where Δm2atm is determined by one of the lightest right-handed neutrinos. 相似文献
109.
Triantafyllos A. Albanis Dominga Bochicchio Sabino A. Bufo Isabella Cospito Maurizio D'Auria Marilena Lekka 《International journal of environmental analytical chemistry》2013,93(8-9):561-569
Photodegradation of two sulfonylurea herbicides, triasulfuron and thifensulfuron-methyl adsorbed on Preveza or Nea Malgara soils (Greece) was studied in outdoor and laboratory experiments. Herbicides on adsorbed phase and kept in the dark were characterised by a high reactivity, giving depletion curves that can be all described by a first order equation. In the irradiation experiments the kinetic behaviour of photodegradation was complex and characterised by a double step photoreaction. After a first period varying from 8 to 24 h the rate of reaction was reduced to 7-31% of the initial rate. The kinetic constant related to the degradation of triasulfuron practically showed the same values of those obtained for thifensulfuron-methyl. The half-lives obtained on Nea Malgara soil were generally higher than those obtained using Preveza soil. The observed behaviour is explained considering the photochemical properties of the herbicides, and the organic matter content of the soils. 相似文献
110.