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91.
A set of Mapuche–Tehuelche composite silver jewellery items, produced in the 19th century and collected in a same indigenous camp in 1896, belonging to the La Vaulx's collection held at the Musée du Quai Branly (Paris), was observed by optical microscopy, scanning electron microscope and X‐radiography, and analysed by PIXE with a 3‐MeV external proton micro‐beam. We aimed to check if these jewels used daily by women evolved during their owners' lifetime, through the analysis of the alloys employed in their making and the silversmith's technologies. Results showed that the jewels were manufactured by different silversmiths, yet using the same workshop traditions. Silver‐based alloys of different compositions were identified. The presence of high Zn and Ni contents in many parts of certain items denotes the use of nickel silver alloys not by direct use of coins and native metals as expected but by remelting and reuse of coins and objects. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
92.
E Aprea F Morisco F Biasioli P Vitaglione L Cappellin C Soukoulis V Lembo F Gasperi G D'Argenio V Fogliano N Caporaso 《Journal of mass spectrometry : JMS》2012,47(9):1098-1103
Breath testing has been largely used as a diagnostic tool, but the difficulties in data interpretation and sample collection have limited its application. We developed a fast (< 20?s), on-line, non-invasive method for the collection and analysis of exhaled breath in awake rats based on proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) and applied it to investigate possible relationships between pathologies induced by dietary regime and breath composition. As a case study, we investigated rats with dietary induced non-alcoholic steatohepatitis (NASH) and modifications induced by coffee addition to the diet. We considered two different diets (standard and high fat) complemented with two different drinking possibilities (water or decaffeinated coffee) for a total of four groups with four rats each. Several spectrometric peaks were reliable markers for both dietary fat content and coffee supplementation. The high resolution and accuracy of PTR-ToF-MS allowed the identification of related compounds such as methanol, dimethyl sulphide, dimethyl sulphone and ammonia. In conclusion, the rapid and minimally invasive breath analysis of awake rats permitted the identification of markers related to diet and specific pathologic conditions and provided a useful tool for broader metabolic investigations. Copyright ? 2012 John Wiley & Sons, Ltd. 相似文献
93.
G Bianco F Lelario FG Battista SA Bufo TR Cataldi 《Journal of mass spectrometry : JMS》2012,47(9):1160-1169
An liquid chromatography-mass spectrometry method using electrospray ionization in negative ion mode coupled with a hybrid quadrupole linear ion trap and Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was applied to characterize of intact glucosinolates (GLSs) in crude sample extracts of wild bud flowers of Capparis spinosa (Capparis species, family Capparaceae). Structural information of GLSs was obtained upon precursor ions' isolation within the FTICR trapping cell and subsequent fragmentation induced by infrared multiphoton dissociation (IRMPD). Such a fragmentation was found very useful in terms of chemical identification of all precursor ions [M-H](-) including sulfur-rich GLSs reported here for the first time. Along with most common GLSs already found in capers such as glucocapparin, isopropyl/n-propyl-GLS, mercapto-glucocapparin, and two indolic GLS, i.e., 4-hydroxyglucobrassicin and glucobrassicin, the occurrence of the uncommon glycinyl-glucocapparin as well as two sulfur-rich GLSs is reported. IRMPD showed an increased selectivity towards disulfide bond cleavages with thiol migration, suggesting the side chain structure of non-targeted compounds, i.e., disulfanyl-glucocapparin and trisulfanyl-glucocapparin. Glucocapparin [2.05?±?0.25?mg/g, dry weight (dw)] was the most abundant GLS, followed by glucobrassicin (232?±?18?μg/g, dw) and 4-hydroxyglucobrassicin (89?±?12?μg/g, dw). All other compounds were present at very low content ranging from 0.5 to 1.5?μg/g dw. Copyright ? 2012 John Wiley & Sons, Ltd. 相似文献
94.
Filomena?Silva Olga?Louren?o Cidália?Pina-Vaz Acácio?G.?Rodrigues Jo?o?A.?Queiroz Fernanda?Concei??o?Domingues 《Journal of fluorescence》2010,20(4):907-914
Flow cytometry provides a rapid and high-content multiparameter analysis of individual microorganisms within a population.
In the past years, several fluorescent stains were developed in order to monitor DNA content distribution and cell-cycle phases,
mainly in eukaryotic cells. Recently, due to its low detection limits, several of these fluorescent stains were also applied
to prokaryotic cells. In this study, the ability of a novel far-red fluorescent stain DRAQ5 in assessing intracellular DNA
content distribution in Escherichia coli DH5α was evaluated. The results showed that a DRAQ5-labelled live E. coli suspension can be obtained by incubation of 1 × 106 cells/mL with 5 μM DRAQ5 in PBS buffer supplemented with EDTA (pH = 7.4) during 30 min at 37 °C. Flow cytometric analysis
of fixed E. coli cells revealed that ethanol should be used in detriment of glutaraldehyde for DRAQ5 labelling. After the analysis of RNase
and DNase digested samples, DRAQ5 was proven to be a specific DNA labelling stain. The present study demonstrates that the
use of DRAQ5 as a DNA-labelling stain provides an easy assessment of intracellular DNA content and cell-cycle phases in Gram-negative
bacteria such as E. coli. 相似文献
95.
96.
The conflict between pH as empirical number in routine control and the pH value regarded as conveying some information concerning the effective concentration or activity of hydrogen ions, aH, has caused much confusion.There are, however, reasons to conclude that the overwhelming amount of thermodynamic data is not sufficiently accurate—either due to ignorance of metrological concepts or due to insufficiently specified measurement processes of fundamental chemical quantities pH.The commonly used seven reference buffer solutions to which primary pH values have been conventional assigned, represent a selection out of a more extensive list, recommended by NBS (now NIST) in 1962. From then onwards conventions concerning the Debye-Hückel model of electrolyte solutions and ionic strength have been revised and the pH(S) values reassessed in conformity but only for these seven reference buffer solutions. The others have, so far remained unchanged, locking harmonisation of the conventionally assigned pH(S) values.In this work, ionic strength is calculated through complete equations derived from the acidity constants. Concentrations of the various species involved in the conventional assignment of pH and their corresponding activity coefficients are therefore, more rigorously known. The process proves particularly useful for poliprotic acids with overlapping acidity constants, where the ratio is less than 103.As a consequence, conventionally assigned pH values of reference buffer solutions are recalculated and corrections are introduced as appropriate. 相似文献
97.
Solution enthalpies of 1-bromoadamantane in 14 monoalcohols were measured at 298.15 K. Comparison with the solution enthalpies of 2-bromo-2-methylpropane was performed. The obtained data were discussed in terms of the effect of solute's size and solvent's structure. 相似文献
98.
Filomena Gon?alves George E. Marnellos Evangelos A. Efthimiadis José L. Figueiredo 《Reaction Kinetics and Catalysis Letters》2003,80(1):153-159
The simultaneous reduction of N2O+NO with carbon supported Ni/K catalysts was studied. High conversions of both compounds were obtained at 400°C, and a synergystic
effect between Ni and K was observed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
99.
Rigano D Arnold NA Conforti F Menichini F Formisano C Piozzi F Senatore F 《Natural product research》2011,25(6):614-626
The essential oil of Nepeta glomerata from Lebanon was studied by means of GC and GC/MS analysis; 70 compounds were identified. The oil was constituted mainly by monoterpenes and the most abundant components were α-pinene, spathulenol and carvacrol. Nepeta glomerata oil showed antibacterial activity, particularly towards Gram-positive bacteria, and also inhibited LPS-induced NO production in macrophage cell line RAW 264.7, with an IC(50) value of 78.1 μg mL(-1). Furthermore, an in?vitro cytotoxic assay showed that the oil was more active on a renal adenocarcinoma cell line (48% of inhibition of proliferation at 100 μg mL(-1)) in comparison to an amelanotic melanoma. 相似文献
100.
Given a smooth compact k-dimensional manifold Λ embedded in ? m , with m≥2 and 1≤k≤m?1, and given ?>0, we define B ? (Λ) to be the geodesic tubular neighborhood of radius ? about Λ. In this paper, we construct positive solutions of the semilinear elliptic equation $$\begin{cases} \Delta u + u^p = 0 &\mbox{in } B_{\epsilon}(\varLambda) \\ u = 0 & \mbox{on } \partial B_{\epsilon}(\varLambda) , \end{cases} $$ when the parameter ? is chosen small enough. In this equation, the exponent p satisfies either p>1 when n:=m?k≤2 or $p\in(1, \frac{n+2}{n-2})$ when n>2. In particular, p can be critical or supercritical in dimension m≥3. As ? tends to 0, the solutions we construct have Morse index tending to infinity. Moreover, using a Pohozaev type argument, we prove that our result is sharp in the sense that there are no positive solutions for $p>\frac{n+2}{n-2}$ , n≥3, if ? is sufficiently small. 相似文献