Application de la chélatométrie au dosage des esters et chlorures de mono-esters oxaliques

Esters and chlorides of oxalic mono-esters can be estimated volumetrically. After saponification precipitation is carried out by means of a calcium chloride solution, the excess of which is measured by chelatometry.     

Multiplicity theorems for superlinear elliptic problems

In this paper we study second order elliptic equations driven by the Laplacian and p-Laplacian differential operators and a nonlinearity which is (p-)superlinear (it satisfies the Ambrosetti–Rabinowitz condition). For the p-Laplacian equations we prove the existence of five nontrivial smooth solutions, namely two positive, two negative and a nodal solution. Finally we indicate how in the semilinear case, Morse theory can be used to produce six nontrivial solutions. This paper was completed while the first author was visiting the University of Aveiro as an Invited Scientist. The hospitality and financial support of the host institution are gratefully acknowledged. The second and third authors acknowledge the partial financial support of the Portuguese Foundation for Science and Technology (FCT) under the research project POCI/MAT/55524/2004.     

Optimal labelling of proteins with acridinium ester

The effects of reaction conditions on the labelling of model proteins (human IgG and BSA) with an acridinium hydroxsuccinimidyl ester are studied. The effect of changes in reaction temperature were minimal. An increase in reaction time increased the amount of labelling, eventually reaching saturation. A higher label/protein ratio produced a proportionally higher label incorporation. The optimal pH of the labelling buffer was found to be pH 8.5. The acridinium-labelled proteins can be detected and quantified in the 4 × 10^?18?3 × 10^?14 mol range.     

Synthesis and photophysical evaluation of meso-phenyl-1,4-dihydropyridineand pyridine-porphyrin hybrids

Chemistry of Heterocyclic Compounds - In the present work, we have synthesized new molecular hybrids consisting of porphyrin ring system connected at the meso positions with phenyl groups and/or,...     

Cladonia verticillaris (lichen) can exhibit defense mechanisms against Rn-222 under controlled conditions

Journal of Radioanalytical and Nuclear Chemistry - This study aimed to evaluate the effects of the Rn-222 progeny on the lichen Cladonia verticillaris under controlled conditions. The results...     

1H NMR-based metabolomics approach for exploring urinary metabolome modifications after acute and chronic physical exercise

Metabolomics is a comprehensive method for metabolite assessment that involves measuring the overall metabolic signature of biological samples. We used this approach to investigate biochemical changes due to acute and chronic physical exercise. Twenty-two women using identical oral contraceptives were segregated into an untrained (n = 10) or trained (n = 12) group depending on their physical training background. The subjects performed two exercises in a randomized order: a prolonged exercise test (75% of their \mathop V^· \textO_2   max \mathop V\limits^\cdot {{\text{O}}_{2\,\;\max }} until exhaustion) and a short-term, intensive exercise test (short-term, intensive exercise anaerobic test). Urine specimens were collected before and 30 min after each test. The samples were analyzed by ¹H NMR spectroscopy, and multivariate statistical techniques were utilized to process the data. Distinguishing characteristics were observed only in the urine profiles of specimens collected before vs. 30 min after the short-term, intensive exercise test. The metabolites responsible for such changes were creatinine, lactate, pyruvate, alanine, β-hydroxybutyrate, acetate, and hypoxanthine. In both groups, the excretion of lactate, pyruvate, alanine, β-hydroxybutyrate, and hypoxanthine increased similarly after the completion of the short-term, intensive exercise test (p < 0.03). However, acetate excretion increased to a lesser extent in trained than in untrained subjects (p < 0.05). In conclusion, metabolomics is a promising tool in order to gain insight into physiological status and to clarify the changes induced by short-term, intense physical exercise.