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Rendiconti del Circolo Matematico di Palermo Series 1 - 相似文献
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Loris Tonidandel Eugenio Ragazzi Pietro Traldi 《Rapid communications in mass spectrometry : RCM》2009,23(3):403-408
Baltic amber contains high levels of succinic acid, most of which is part of the polymer framework, and only recently has the presence of microcrystals of free succinic acid been documented by scanning electron microscopy and X‐ray diffraction analysis. The determination of succinic acid can be used for an easy identification of Baltic amber among other fossil resins and to distinguish it from imitations, widely diffused on the market, produced with natural or modified recent or sub‐fossil resins, such as copals. We report here a simple method, based on negative ion electrospray ionization mass spectrometry, for evaluating the free succinic acid content in water/methanol extracts of ambers from different origin, using a sample of about 20 mg. The limit of quantification is better than 1 ppm and, when applied to a set of amber samples of different origin, it was able to distinguish those of Baltic origin (showing free succinic acid levels in the range 50–400 ppm) from the others (for which succinic acid was undetectable, i.e. at levels lower than 1 ppm). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Pietro Lura Frank Winnefeld Stefanie Klemm 《Journal of Thermal Analysis and Calorimetry》2010,101(3):925-932
Isothermal calorimetry and chemical shrinkage measurements are two independent techniques used to study the development of
hydration in cementitious systems. In this study, calorimetry and chemical shrinkage measurements were combined and simultaneously
performed on hydrating cement paste samples. Portland cement pastes with different water to cement ratios and a cement paste
containing calcium sulfoaluminate clinker and anhydrite were studied. The combined calorimetry/chemical shrinkage test showed
good reproducibility and revealed the different hydration behavior of sealed samples and open samples, i.e., samples exposed
to external water during hydration. Large differences between sealed and open samples were observed in a Portland cement paste
with low water to cement ratio and in the calcium sulfoaluminate paste; these effects are attributed to self-desiccation of
the sealed pastes. Once the setup is fully automatized, it is expected that combined calorimetry/chemical shrinkage measurements
can be routinely used for investigating cement hydration. 相似文献
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Cali F Ragalmuto A Chiavetta V Calabrese G Fichera M Vinci M Ruggeri G Schinocca P Sturnio M Romano S Romano V Elia M 《Experimental & molecular medicine》2010,42(12):842-848
Angelman syndrome (AS) is a severe neurobehavioural disorder caused by failure of expression of the maternal copy of the imprinted domain located on 15q11-q13. There are different mechanisms leading to AS: maternal microdeletion, uniparental disomy, defects in a putative imprinting centre, mutations of the E3 ubiquitin protein ligase (UBE3A) gene. However, some of suspected cases of AS are still scored negative to all the latter mutations. Recently, it has been shown that a proportion of negative cases bear large deletions overlapping one or more exons of the UBE3A gene. These deletions are difficult to detect by conventional gene-scanning methods due to the masking effect by the non-deleted allele. In this study, we have used for the first time multiplex ligation-dependent probe amplification (MLPA) and comparative multiplex dosage analysis (CMDA) to search for large deletions affecting the UBE3A gene. Using this approach, we identified a novel causative deletion involving exon 8 in an affected sibling. Based on our results, we propose the use of MLPA as a fast, accurate and inexpensive test to detect large deletions in the UBE3A gene in a small but significant percentage of AS patients. 相似文献
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