Continuous monitoring of shelf lives of materials by application of data loggers with implemented kinetic parameters

The evaluation of the shelf life of, for example, food, pharmaceutical materials, polymers, and energetic materials at room or daily climate fluctuation temperatures requires kinetic analysis in temperature ranges which are as similar as possible to those at which the products will be stored or transported in. A comparison of the results of the evaluation of the shelf life of a propellant and a vaccine calculated by advanced kinetics and simplified 0th and 1st order kinetic models is presented. The obtained simulations show that the application of simplified kinetics or the commonly used mean kinetic temperature approach may result in an imprecise estimation of the shelf life. The implementation of the kinetic parameters obtained fromadvanced kinetic analyses into programmable data loggers allows the continuous online evaluation and display on a smartphone of the current extent of the deterioration of materials. The proposed approach is universal and can be used for any goods, any methods of shelf life determination, and any type of data loggers. Presented in this study, the continuous evaluation of the shelf life of perishable goods based on the Internet of Things (IoT) paradigm helps in the optimal storage/shipment and results in a significant decrease of waste

Catabolisme de la chlorophylle b: structures, mécanismes et synthèse

L’isolation et la caractérisation d’un nouveau catabolite de la chlorophylle (chl) à partir d’un Magnolia cultivé au jardin botanique de l’Université de Fribourg, Suisse. Un catabolite de la chlorophylle provenant du Mognolia hybr. spec. hort. a été isolé et purifié. Des expériences de dégradation chimique et de spectrométrie de masse ont montré que le nouveau catabolite possède une constitution similaire aux catabolites de la chlorophylle déjà isolés à partir de Cercidiphyllum japonicum et de Brassica napus. La différence entre ces catabolites consiste en la présence d’un résidu glycosylique lié de manière covalente au groupe hydroxy de la chaîne latérale éthyle du catabolite. Une détermination sûre de la constitution du catabolite a été empêchée par l’insolubilité inhérente du composé dans les solvants adéquats, ce qui n’a pas permis d’obtenir un spectre RMN suffisamment résolu. Démonstration de la conversion de la chl b en chl a avant dégradation dans les plantes supérieures. La chl b constitue le pigment secondaire du système collecteur de lumière dans les plantes supérieures et dans les algues vertes. Elle représente 30% de la quantité totale de chlorophylle. Avec la découverte d’un cycle d’interconversion chl a( b) il a été avancé que dans les plantes évoluées la chl b est convertie en chl a avant dégradation. Ce travail met en évidence, par spéctrométrie à haute résolution RMN-1H , –2H et de masse, qu’une fraction significative du groupe méthyle clé du catabolite contient un atome de deutérium lorsque les feuilles d’orge ( Hordeum vulgare) sont placées dans l’obscurité en présence d’eau deutérée à 80%. Ces résultats indiquent que la chl b est convertie en chl a avant dégradation, ce qui signifie que le catabolite isolé jusqu’ici provient des chl a et b. Il est surprenant de ne trouver l’insertion que d’un atome de deutérium dans le groupe méthyle du catabolite provenant de la chl b. Ceci suggère l’implication d’au moins deux enzymes rédox différentes. De ce résultat, on peut conclure que le cofacteur du premier enzyme transfert un hydrure et que le cofacteur du second utilise un (des) électron(s). L’absence de marquage sur les autres groupes méthyle du catabolite confirme qu’à l’exception de conversion chl b(a), les angiospermes ne forment pas de chlorophylle dans l’obscurité. Synthèse des maléimides, fragments obtenus lors de la procédure de dégradation chimique de catabolites de la chlorophylle. Cette partie du travail traite de la synthèse partielle et totale des maléimides isolés lors de la dégradation à l’acide chromique des catabolites de la chlorophylle susmentionnés. Pour cela, des dérivés appropriés de la protoporphyrine IX, des pyrroles substitués aux positions 3 et 4, et d’autres dérivés de pyrrole ont été synthétisés et traités avec de l’acide chromique. Bien que les quantités obtenues restent restreintes, les deux méthodes ont fourni les maléimides désirés.Isolation and characterization of a new chlorophyll (chl) catabolite from a Magnolia species collected at the Botanical Garden of the University of Fribourg, Switzerland. A chlorophyll catabolite of Magnolia hybr. spec. hort. was isolated and purified. Chemical degradation experiments and mass spectroscopic investigation showed that the new catabolite has a similar constitution as the catabolites previously isolated from Cercidiphyllum japonicum and Brassica napus. The difference between them appears to be the presence of a glycosylic residue, which is covalently attached to the hydroxy group of the ethyl side chain of the catabolite. A secure elucidation of constitution was hampered by the inherent insolubility of the compound in suitable solvents, which did not allowed to obtain sufficiently resolved NMR spectra. Experimental proof that in higher plants chl b is converted to chl a before degradation. Chl b occurs as an accessory pigment of the light harvesting systems in higher plants and green algae, and comprises up to 30% of the total Chls. With the discovery of the Chl b( a) interconversion cycle it has been occasionally speculated that in higher plants Chl b is converted to Chl a before degradation. This work evidences, by high resolution 1H-, 2H- NMR and MS-ICR spectroscopic methods, that a significant fraction of the key methyl group of the Chl a catabolite becomes mono-deuterium labelled when green barley leaves ( Hordeum vulgare) are de-greened by permanent darkness in heavy water (80 atom% 2H). These results indicate that Chl b is converted to Chl a before degradation i.e. the Chl a catabolite isolated has emerged from both Chl a and Chl b. It was surprising to find that exclusively one deuterium atom was incorporated into the methyl-group of the Chl b catabolite. This result suggests the involvement of at least two distinguishable redox enzymes. From this result, it was concluded that the cofactor of the first enzyme transfers a hydride ion and that the cofactor of the second one mediates electron(s). The lack of label in the remaining methyl groups of the catabolite confirms, except from Chl b( a) conversion, the general assumption that angiosperms form no Chl in the dark. Chemical synthesis of the corresponding maleimide fragments obtained from the chemical degradation procedure of the chlorophyll catabolites. This part deals with the partial and total chemical synthesis of the maleimides isolated from the chromic acid degradation products of the above mentioned chlorophyll catabolite. For this purpose, suitable protoporphyrin IX derivatives, 3,4-substituted pyrroles and pyrrol derivatives were synthesized and subsequently treated with chromic acid. Both methods yielded the desired maleimides although, up to now, only in small quantities

Thermal Stability of Explosives

Thermal decomposition rates and mechanisms of explosives are of obvious importance to efforts designed to enhance safety in manufacturing, storage and handling of these energetic materials. To assess the thermal stability of energetic materials a series of analyses have to be performed. This paper gives an overview on the classical tests used to establish the safety parameters. The modern analytical methods applied today are also presented and illustrated. The development of technology and the use of advanced numerical techniques such as AKTS-TA-Software® enables prediction of the reaction progress of materials in broad temperature ranges. In fact, the goal for numerical simulations is to replace experiments in situations when direct accessibility to the test item or set-up is not possible for timing or safety reasons. The introduction of such new methodology will lead to approaches as close as possible to the reality but will never be able to reach it

Propellant Chemistry

A systematic overview of the different types of solid propellants, their chemical compositions, characteristics and practical applications is given. The classification of propellants, the function of stabilizers and the modification of the ballistic properties are discussed

Propellant Chemistry

A systematic overview of the different types of solid propellants, their chemical compositions, characteristics and practical applications is given. The classification of propellants, the function of stabilizers and the modification of the ballistic properties are discussed

New light on the evolutionary history of the common goby (Pomatoschistus microps) with an emphasis on colonization processes in the Mediterranean Sea.

Through the study of the phylogeographic structure and demographic history of the common goby, Pomatoschistus microps, the influence of Quaternary climatic changes on the evolutionary history of coastal and marine fishes is investigated. Because of its sedentary life cycle in Mediterranean lagoons, it is also a good model to study more specifically if the formation of lagoons during the Holocene had an impact on population structure and demography. Mitochondrial sequences of Northeastern Atlantic and Western Mediterranean specimens were used for phylogenetic reconstructions as well as divergence time estimates, demographic history and population structure analyses. Pomatoschistus microps was a highly supported monophyletic clade including four lineages. It may have appeared 77,000 yr ago, and the divergence of its lineages likely occured shortly thereafter (between 61,000 and 54,000 yr). Most lineages had polytomic topologies, low nucleotide diversity and demographic analyses providing evidence of population expansion. Each lineage was characterized by a large number of private haplotypes. Most haplotypes found in Mediterranean localities were endemic, and one was dominant. Complex reticulated relationships connecting North European, Atlantic and Mediterranean haplotypes were observed. Moderate to high population structure was underlined. Contrary to previous published studies, no significant differentiation was observed between Atlantic and Mediterranean populations, indicating that the Gibraltar Strait is not a phylogeographic break for P. microps. Indeed, molecular dating combined with the tree topologies, phylogeographic and demographic analyses as well as high haplotype diversity underline a recent and rapid population divergence during the last glacial. However, population structure indicates that differentiation is an ongoing process. From an ancestral population trapped in the Atlantic, this goby colonized first northern Europe and later the Mediterranean Sea. Shared haplotypes could have dispersed in the western Mediterranean basin before the lagoon formation, while most private haplotypes, evidencing a recent isolation, probably diverged in lagoons after their closure

Prediction of thermal stability of materials by modified kinetic and model selection approaches based on limited amount of experimental points

The experimental data collected in the discontinuous mode are often used for the computation of reaction kinetics and, further, for the simulation of the thermal stability of materials. However, the kinetic calculations based on limited amount of sparse points require specific criteria allowing correct choice of the best kinetic model. We present the modified kinetic computations allowing considering one, two or even more reaction stages by applying unlimited amount of combinations of different kinetic models for the best description of the reaction course. The kinetic parameters are calculated using the truncated Šesták-Berggren (SB) approach and further verified by using the Akaike and Bayesian information criteria (AIC and BIC, respectively). The proposed method of kinetic and model selection for elaboration of sparse points were checked by the simulation of generated points with known, arbitrarily chosen kinetic parameters containing some scatter. The verified procedure was applied for the prediction of the thermal stability of energetic (propellant) and biological (vaccine) materials characterized by approximately 30 experimental data points

Genetic diversity indices for each <i>Pomatoschistus microps</i> lineage.

a<p>Number of sequences.</p>b<p>Number of haplotypes.</p>c<p>Nucleotide diversity (sd = standard deviation).</p>d<p>Haplotype diversity (sd = standard deviation).</p>e<p>Mean number of pairwise differences.</p

Demographic history of <i>Pomatoschistus microps</i> inferred from concatenated control region and cytochrome <i>b</i> gene sequences.

<p>Observed mismatch distributions (grey line) for each lineage are compared to expected distributions (black line) under a population growth-decline model.</p

Maximum-likelihood tree reconstructed from concatenated control region and cytochrome <i>b</i> gene sequences from <i>Pomatoschistus microps</i>.

<p><b>A</b>. Individual labels are detailed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091576#pone.0091576.s005" target="_blank">Table S1</a>. Individuals with • are from an Atlantic locality, whereas individuals with blue * and red star are, respectively, from northern Europe and Mediterranean localities. Numbers at nodes are for ML bootstrap percentages (≥50%). <b>B</b>. Numbers at nodes are for divergence times (Myr) estimated with PAML and based on a geologic calibration point, 6.05±0.09 Myr (between 6.14 and 5.96 Myr) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091576#pone.0091576-Rouchy1" target="_blank">[7]</a>. For both figures, <i>P. microps</i> lineages are indicated on the right.</p