Conservação e restauro de uma urna em vidro do século I d.C., encontrada em Mértola (Portugal)

International audienceThe evolution of capillary forces during evap-oration and the corresponding changes in the geometrical characteristics of liquid (water) bridges between two glass spheres with constant separation are examined experimen-tally. For comparison, the liquid bridges were also tested for mechanical extension (at constant volume). The obtained results reveal substantial differences between the evolution of capillary force due to evaporation and the evolution due to extension of the liquid bridges. During both evaporation and extension, the change of interparticle capillary forces consists in a force decrease to zero either gradually or via rupture of the bridge. At small separations between the grains (short & wide bridges) during evaporation and at large volumes during extension, there is a slight initial increase of force. During evaporation, the capillary force decreases slowly at the begin-ning of the process and quickly at the end of the process; during extension, the capillary force decreases quickly at the beginning and slowly at the end of the process. Rup-ture during evaporation of the bridges occurs most abruptly for bridges with wider separations (tall and thin), sometimes occurring after only 25 % of the water volume was evapo-rated. The evolution (pinning/depinning) of two geometri-cal characteristics of the bridge, the diameter of the three-phase contact line and the "apparent" contact angle at the solid/liquid/gas interface, seem to control the capillary force evolution. The findings are of relevance to the mechanics of unsaturated granular media in the final phase of drying

Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry

Objective: The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase

Ulepszona procedura izolacji i przygotowania do analizy w ukłądzie GC-MS lotnych produktów reakcji Maillarda

The new method of isolation and preparation for GC-MS analysis of volatile compounds from processed meat and Model Maillard reactions products was investigated. Volatiles after separation with nitrogen stream were trapped in cooled (with solid CO₂ - ethanol bath) steel pipe, filled with glass beeds and subsequently washed out with diethyl ether. The results obtained showed usefulness of this method both for model systems and foodstuffs as well.Przebadano możliwość wydzielenia i przygotowania do analizy w układzie chromatograf gazowy-spektrometr masowy lotnych produktów reakcji Maillarda z układów modelowych typu aminokwas-cukier oraz lotnych związków zapachowych wydzielonych z polędwicy wołowej pieczonej. Stwierdzono, iż metoda polegająca na wydzieleniu tych związków strumieniem gazu obojętnego, osadzeniu ich na nośniku o umiarkowanie rozwiniętej powierzchni (szklane perełki 80/100 mesh) umieszczonym w kolumnie pomocniczej, a następnie wymyciu ich eterem, umożliwia otrzymanie próbki odpowiedniej do przeprowadzenia takiej analizy. Łagodne warunki wydzielania i wymywania powodują, iż tworzenie się artefaktów jest mało prawdopodobne. Chłodzenie kolumny pomocniczej do niskich temperatur umożliwia wyłapanie związków o szerokim spektrum temperatur wrzenia. Metoda może znaleźć ogólne zastosowanie do badania lotnych związków produktów spożywczych

Investigation (detection ) of microbal environmental contamination by mass spectrometry. Part I. Muramic acid as a biomarker of the microbial cell walls

Microorganisms synthesize several monomeric chemical structures that are not found elsewhere in nature, e.g. muramic acid (an amino sugar) and D-amino acids (D-alanine and D-glutamic acid) are ubiquitous in bacterial peptidoglycan (PG). Specific sugars (e.g. heptoses) and 3-hydroxylated fatty acids are found in the endotoxin (lipopolysaccharide, LPS) of gram-negative bacteria [42]. The best way to protect against environmental contamination is microbial control. Methods in current use for monitoring of microorganisms mainly include culturing and direct microscopy. However, several factors including samples collection, growth conditions, incubation temperature and interaction between different organisms all affect culturing results. Additionally, culturing based methods can detect only viable organisms and they are also time consuming, sometimes taking days or weeks. However, since both living and dead microorganisms express irritating and toxic structures, they should all be taken into consideration [17]. Muramic acid (MuAc), an amino sugar, has been suggested for use as a chemical marker in gas chromatography-mass spectrometry (GC-MS) determination of bacterial peptidoglycan in both clinical and environmental samples. Several derivatives of MuAc have been applied, including the alditol acetate [1, 2], aldononitrile [3], trifluoroacetyl [4] and trimethylsilyl [5], and methyl ester O-methyl acetate [6] derivatives. Both the alditol acetate and TMS derivatives have proven suitable for the use with GC-ion-trap tandem MS [7]. The aim of our proposition is a trial of application of gas chromatography-mass spectrometry (GC-MS) method as an alternative or complement to culturing, microscopy and other assays for detection, characterization and monitoring of microbial contamination of environment (e.g. water, air, air-conditioning systems), contamination of biochemical and food production chain processes, packaging for foodstuffs etc. by direct analysis of bacterial muramic acid as a biochemical marker. A method is described for the quantitation of muramic acid, a marker of bacterial peptidoglycan as trimethylsilyl (TMS ) derivatives using GC/MS method. The described methods are fast and simple, and can be applied for monitoring of microbial contamination directly, without prior culturing, in complex environmental samples. This method can also be applied for testing processes of cleaning and disinfection on packaging materials or on both packaging materials/foodstuffs in order to decrease their microbial load and thus to ensure better shelf-life

Investigetion (detection) of environment microbial contamination by mass spectrometry. Part 2, 3-hydroxy fatty acids as a lipopolysaccharides (endotoxin) biomarkers of the gram-negative bacterial cell walls

Microorganisms synthesize several monomeric chemical structures that are not found elsewhere in nature, e.g. muramic acid (an amino sugar) and D-amino acids (D-alanine and D-glutamic acid) are ubiquitous in bacterial peptidoglycan (PG). Characteristic sugars (e.g. heptoses) and 3-hydroxylated fatty acids are found in the endotoxin (lipopolysaccharide, LPS) of gram-negative bacteria [1]. The best way to protect against environment contamination is microbial control. Methods in current use for monitoring microorganisms mainly include culture and direct microscopy. However, several factors, including samples collection, growth conditions, incubation temperature and interaction between different organisms all affected the culture results. Additionally, culture based methods can detect only viable organisms and they are also time consuming, sometimes taking days or weeks. However, since both living and dead microorganisms express irritating and toxic structures, they should all be taken into consideration. Muramic acid has been suggested for use as a chemical marker in gas chromatography-mass spectrometry (GC-MS) determination of bacterial peptidoglycan [2]. While 3-hydroxylated fatty acids are the best proposition for use as a chemical markers in gas chromatography-mass spectrometry determination of bacterial lipopolysaccharide (endotoxin) of gram-negative bacteria in both clinical and environmental samples [38]. Two derivatives have been applied, including the trimethylsilyl (TMS) and pentafluorobenzoyl (PFBO) derivatives [80]. Both derivatives (TMS and PFBO) have been proven suitable for use with GC-ion-trap tandem MS [3]. The aim of our proposition is trial of application of gas chromatography-mass spectrometry (GC-MS) method as an alternative or complement to culturing, microscopy and other assays for detection, characterization and monitoring of microbial contamination of environment (e.g. water, air, air-conditioning systems), contamination of biochemical and food production chain processes, packaging for foodstuffs etc. by analysis of bacterial 3-hydroxylated fatty acids as a biochemical markers. A method is described for the quantitation of methyl esters of 3-hydroxyacids, markers of bacterial lipopolysaccharide (endotoxin), as trimethylsilyl or pentafluorobenzoyl derivatives using GC/MS method. The described methods are quick and simple, can be applied for monitoring microbial contamination directly, without prior culturing, in complex environmental samples. This method can be also applied for testing processes of cleaning and disinfections on packaging materials or on both packaging materials/foodstuffs in order to decrease their microbial load and thus to ensure better shelf-life. [1] Z. Mielniczuk, K. Bal, Spektrometria mas w badaniach skażeń mikrobiologicznych środowiska. Część I. Kwas muraminowy jako biomarker ścian komórkowych bakterii, Wiad. Chem., 2012, 66, 445. [2] K. Bal, L. Larsson, E. Mielniczuk, Z. Mielniczuk, Structure of muramic acid TMS derivative mass spectrum’s base ion (m/z=185) used for quantification of bacterial peptidoglycan, J. Microbiol. Meth., 2002, 48, 267. [3] A. Saraf, L. Larsson, Identification of microorganisms by mass spectrometry, Advances in Mass Spectrometry, 1998, 14, 449. [38] Z. Mielniczuk, E. Mielniczuk, L. Larsson, Gas chromatography-mass spectrometry methods for analysis of 2- and 3-hydroxylated fatty acids: Application for endotoxin measurement, J. Microbiol. Meth., 1993, 17, 91. [80] Z. Mielniczuk, S. Alugupalli, E. Mielniczuk, L. Larsson, Gas chromatography-mass spectrometry of lipopolysaccharide 3-hydroxy fatty acids: comparison of pentafluorobenzoyl and trimethylsilyl methyl ester derivatives, J. Chromatogr., 1992, 623, 115

Crystallisation of Amorphous Y50Cu42Al8Y_{50}Cu_{42}Al_8 Alloy

Amorphous $Y_{50}Cu_{42}Al_8$ ribbon was prepared by melt-spinning technique on the Cu wheel. The crystallisation process was analysed by differential scanning calorimetry and X-ray diffraction. Differential scanning calorimetry curves characterising two crystallisation stages of $Y_{50}Cu_{42}Al_8$ alloy were measured in non-isothermal dynamic mode at different heating rates. Activation energies of both steps of crystallisation process were acquired by the Kissinger method and are equal to 570± 56 and 290±29 kJ/mol for the first and second stage, respectively. By annealing the ribbon at a given temperature for various times the nanocrystalline phase grains of the sizes of about 40 nm in diameter were created. The influence of the annealing temperature on the grain size evolution was also examined