Identification of antioxidant by-products based on their specific chemistry and their potential detection during SUS extractable study

Single-use films in biopharmaceutical and biotechnology industries are mainly made from polymers such as PE, EVA and EVOH. Depending upon the environmental aggressiveness during various stages of the polymer lifetime, additives are added to protect them such as substituted hindered phenols acting as antioxidants, melt (processing) stabilizers, and to some extent as photo-antioxidants. Ionizing radiation effects on polymers have been widely investigated. They consist mainly of free radicals production. These free radicals can in turn lead to degradation and or crosslinking phenomena (release of gases, discoloration, changes in mechanical properties and gas permeability, degradation and leaching of polymer additives into solvents, etc.) whose extent depends on many factors. In contrast, there is little information on the effect of ionizing radiation on the additive package properties used in multilayer packaging films. A specific influence on chemical transformations of phenols is induced as well. Strong discoloration of the polymer stabilized with phenolic antioxidants originates for instance mainly from the reaction products of the stabilizers. The color development can be attributed to the formation of conjugated diene compounds, arising as a consequence of trapping of radicals by phenolics. The discoloration depends on the structure and concentration of the phenolic transformation products. As a result of the described complexity, a huge variety of potential extractable compounds can be expected from antioxidants. This work focuses of highlighting the degradation products we may expect from the thermal and radiative degradation of the primary and secondary anti-oxidants and to address complexity of identifying properly the by-products one may detect in extractable study applied to pharmaceutical single use products

Gut microbiome patterns depending on children's psychosocial stress : reports versus biomarkers

Aim: Chronic stress increases disease vulnerability factors including inflammation, a pathological characteristic potentially regulated by the gut microbiota. We checked the association between the gut microbiome and psychosocial stress in children/adolescents and investigated which stress parameter (negative versus positive emotion, self-report versus parental report, events versus emotions, biomarker cortisol versus parasympathetic activity) is the most relevant indicator herein. Methods: Gut microbiome sequencing was completed in fecal samples from 93 Belgian 8-16y olds. Stress measures included negative events, negative emotions, emotional problems reported by parents, happiness, hair cortisol and heart rate variability (pnn50 parameter reflecting parasympathetic activity). Alpha diversity, beta diversity and linear discriminant analysis were the unadjusted analyses. Age, sex, socio-economic status, diet, physical activity, sleep and weight status were adjusted for via a redundancy analysis and differential abundance via zero-inflated negative binomial regression. Results: High stress as reflected by low pnn50 and more negative events were associated with a lower alpha diversity as indicated by the Simpson index. Happiness and pnn50 showed significant differences between high and low stress groups based on weighted UniFrac distance, and this remained significant after confounder adjustment. Adjusted and unadjusted taxonomic differences were also most pronounced for happiness and pnn50 being associated respectively with 24 OTU (=11.8% of bacterial counts) and 31 OTU (=13.0%). As a general pattern, high stress was associated with lower Firmicutes at the phylum level and higher Bacteroides, Parabacteroides, Rhodococcus, Methanobrevibacter and Roseburia but lower Phascolarctobacterium at genus level. Several genera gave conflicting results between different stress measures e.g. Ruminococcaceae UCG014, Tenericutes, Eubacterium coprostanoligenes, Prevotella 9 and Christensenellaceae R7. Differential results in preadolescents versus adolescents were also evident. Conclusion: Even in this young healthy population, stress parameters were cross-sectionally associated with gut microbial composition but this relationship was instrument specific. Positive emotions and parasympathetic activity appeared the strongest parameters and should be integrated in future microbiota projects amongst other stress measures

Experimental and theoretical investigation of BCl_3 decomposition in H_2

International audienceA combined experimental and theoretical study of the homogeneous decomposition of BCl3 in a H2 carrier gas is presented. A detailed description of the B/Cl/H thermodynamic equilibrium is first obtained from ab-initio calculations from which a restricted low energy chemical mechanism is identified to model the decomposition of BCl3. Transition state theory is then invoked to obtain reaction rates and the resulting kinetic mechanism is incorporated in a 1D model of a CVD reactor. Comparison of calculated steady state concentrations with in-situ FT-IR measurements shows a good agreement at low temperatures, thus validating the kinetic model. The divergence observed at higher temperatures is attributed to boron deposition

CVD and CVI of pyrocarbon from various precursors

International audienceThe control of pyrocarbon (pyC) chemical vapor infiltration (CVI) is a key issue in the processing of high-performance C/C composites with applications in aerospace parts and braking technology. For years, the precise investigation of deposition kinetics and pyC nanometerscale anisotropy has been rehearsed in chemical vapor deposition (CVD) and several variants of CVI with various pore sizes, and using mostly propane, propylene, and methane as source precursors. A literature survey and the analysis of recent experimental data have helped to understand better the role of gas-phase intermediate species in the various nanotextural transitions; a coherent modeling frame, which is suitable for propane, propylene, and methane—the latter having a neatly lower reactivity—has been set up and tested against experimental results from independent teams. The relation between nanotexture and processing conditions is then explained

Optimization of somatic cell injection in the perspective of nuclear transfer in goldfish

<p>Abstract</p> <p>Background</p> <p>Nuclear transfer has the potential to become one strategy for fish genetic resources management, by allowing fish reconstruction from cryopreserved somatic cells. Survival rates after nuclear transfer are still low however. The part played by unsuitable handling conditions is often questioned, but the different steps in the procedure are difficult to address separately. In this work led on goldfish (<it>Carassius auratus</it>), the step of somatic cells injection was explored. Non-enucleated metaphase II oocytes were used as a template to explore the toxicity of the injection medium, to estimate the best location where the cell should be injected, and to assess the delay necessary between cell injection and oocyte activation.</p> <p>Results</p> <p>Trout coelomic fluid was the most suitable medium to maintain freshly spawned oocytes at the metaphase II stage during oocyte manipulation. Oocytes were then injected with several media to test their toxicity on embryo development after fertilization. Trout coelomic fluid was the least toxic medium after injection, and the smallest injected volume (10 pL) allowed the same hatching rates as the non injected controls (84.8% ± 23). In somatic cell transfer experiments using non enucleated metaphase II oocytes as recipient, cell plasma membrane was ruptured within one minute after injection. Cell injection at the top of the animal pole in the oocyte allowed higher development rates than cell injection deeper within the oocyte (respectively 59% and 23% at mid-blastula stage). Embryo development rates were also higher when oocyte activation was delayed for 30 min after cell injection than when activation was induced without delay (respectively 72% and 48% at mid-blastula stage).</p> <p>Conclusions</p> <p>The best ability of goldfish oocytes to sustain embryo development was obtained when the carrier medium was trout coelomic fluid, when the cell was injected close to the animal pole, and when oocyte activation was induced 30 min after somatic cell injection. Although the experiments were not designed to produce characterized clones, application of these parameters to somatic cell nuclear transfer experiments in enucleated metaphase II oocytes is expected to improve the quality of the reconstructed embryos.</p

DNA-Accelerated Catalysis of Carbene-Transfer Reactions by a DNA/Cationic Iron Porphyrin Hybrid

A novel DNA-based hybrid catalyst comprised of salmon testes DNA and an iron(III) complex of a cationic meso-tetrakis(N-alkylpyridyl)porphyrin was developed. When the N-methyl substituents were placed at the ortho position with respect to the porphyrin ring, high reactivity in catalytic carbene-transfer reactions was observed under mild conditions, as demonstrated in the catalytic enantioselective cyclopropanation of styrene derivatives with ethyl diazoacetate (EDA) as the carbene precursor. A remarkable feature of this catalytic system is the large DNA-induced rate acceleration observed in this reaction and the related dimerization of EDA. It is proposed that high effective molarity of all components of the reaction in or near the DNA is one of the key contributors to this unique reactivity. This study demonstrates that the concept of DNA-based asymmetric catalysis can be expanded into the realm of organometallic chemistry

Psychosocial stress and inflammation driving tryptophan breakdown in children and adolescents : a cross-sectional analysis of two cohorts

Background: Tryptophan breakdown is an important mechanism in several diseases e.g. inflammation and stress induced inflammation have been associated with the development of depression via enhanced tryptophan breakdown. Depression is a major public health problem which commonly starts during adolescence, thus identifying underlying mechanisms during early life is crucial in prevention. The aim of this work was to verify whether independent and interacting associations of psychosocial stress and inflammation on tryptophan breakdown already exist in children and adolescents as a vulnerable age group. Methods: Two cross-sectional population-based samples of children/adolescents (8-18 y) were available: 315 from the European HELENA study and 164 from the Belgian ChiBS study. In fasting serum samples, tryptophan, kynurenine, kynurenic acid, C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, soluble vascular adhesion molecule 1 (sVCAM1) and soluble intercellular adhesion molecule 1 (sICAM1) were measured. Psychological stress was measured by stress reports (subjective) and cortisol (objective - awakening salivary cortisol or hair cortisol). Linear regressions with stress or inflammation as predictor were adjusted for age, sex, body mass index, puberty, socio-economic status and country. Results: In both cohorts, inflammation as measured by higher levels of CRP, sVCAM1 and sICAM1 was associated with kynurenine/tryptophan ratio and thus enhanced tryptophan breakdown (beta: 0.145-0.429). Psychological stress was only associated with tryptophan breakdown in the presence of higher inflammatory levels (TNF-alpha in both populations). Conclusions: Inflammatory levels were replicable key in enhancing tryptophan breakdown along the kynurenine pathway, even at young age and in a non-clinical sample. The stress-inflammation interaction indicated that only the stress exposures inducing higher inflammatory levels (or in an already existing inflammatory status) were associated with more tryptophan breakdown. This data further contributes to our understanding of pathways to disease development, and may help identifying those more likely to develop stress or inflammation-related illnesses

Imidazolylidene Cu(II) complexes: synthesis using imidazolium carboxylate precursors and structure rearrangement pathways

Copper(II) complexes of type (NHC)CuX2 (X = OAc, Cl, Br, BF4, NO3) bearing monodentate N-heterocyclic carbenes (NHCs) were prepared by in situ decarboxylation of imidazolium carboxylates as a new synthetic methodology for Cu(II)-NHC complexes. In contrast to the classical deprotonation method, the decarboxylation protocol does not require anaerobic conditions and provides access to complexes with NHCs that are unstable as free carbenes such as N,N’-diisopropyl-imidazolylidene and N,N’-dimethyl-imidazolylidene. Spectroscopic evidence of the formation of the Cu‒CNHC bond is provided by UV-vis and EPR, in particular by the 44 MHz carbene hyperfine coupling constant using a 13C-labelled imidazolylidene ligand. A variation of the nature of the carbene N-substituents and the anions bound to the Cu(II) center is possible with this methodology. These variations strongly influence the stability of the complexes. Structural rearrangement and ligand reorganization was observed during recrystallisation, which are comprised of heterolytic Cu‒CNHC bond dissociation for unstable NHC ligands as well as homolytic Cu‒X bond cleavage and disproportionation reactions depending on the nature of the anion X in the copper complex