Peptides released from acid goat whey by a yeast-lactobacillus association isolated from cheese microflora

Seven lactobacilli and a variety of microflora extracted from twenty five commercial cheeses were grown on unsupplemented acid goat whey and screened for their capacity to hydrolyse whey proteins [alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg)] and to generate peptides. Fermentations were performed aerobically or anaerobically at 37 degrees C using crude or pre-heated whey (10 min at 65, 75 or 85 degrees C). Under aerobic conditions, growth of lactobacilli was poor and protein hydrolysis did not occur. Anaerobic conditions slightly increased lactobacilli growth but neither beta-lg hydrolysis nor peptide generation were observed. More than 50% of alpha-la was digested into a truncated form of alpha-la (+/- 12 kDa) in crude whey and whey pre-heated at 65 degrees C. Twenty-five microflora extracted from raw milk cheeses were screened for their proteolytic activities on acid goat whey under the conditions previously described. Eight of them were able to hydrolyse up to 50% of alpha-la mainly during aerobic growth on crude or pre-heated whey. The corresponding hydrolysates were enriched in peptides. The hydrolysate involving microflora extracted from Comté cheese after or at 18 months ripening was the only one to exhibit hydrolysis of both alpha-la and beta-lg. Microbiological analysis showed that microorganisms originating from Comté cheese and capable of growth on unsupplemented whey consisted of Candida parapsilosis and Lactobacillus paracasei. Fermentation kinetic profiles suggested that peptides were released from alpha-la hydrolysis. The co-culture of both microorganisms was required for alpha-la hydrolysis that occurred concomitantly with the pH decrease. During whey fermentation, Cand. parapsilosis excrete at least one protease responsible for alpha-la hydrolysis, and Lb. paracasei is responsible for medium acidification that is required for protease activation.     

A space-exact beam element for time-dependent analysis of composite members with discrete shear connection

This paper presents a space-exact, time-discretized solution for the time-dependent analysis of composite beams with partial interaction. The time effects considered in this model are creep and shrinkage of the concrete slab. The constitutive model adopted to describe the time effects is linear viscoelasticity with time-dependent coefficients to account for ageing. By using the time-discretized form of the constitutive relations, the equilibrium equations in terms of the displacements at a generic instant are analytically solved. Based on the analytical expressions (exact in space) of the displacements and the internal forces, the space-exact stiffness matrix is deduced for a generic composite beam element. This stiffness matrix can be used in a displacement-based procedure for the time-analysis of continuous composite steel-concrete beams with arbitrary support and loading conditions. The present formulation requires a minimum number of elements depending on the support and loading conditions. The proposed hybrid analytical-numerical method is used to investigate both the short-term and the long-term deflections of simply supported composite beams in order to assess the calculation method proposed in Eurocode EN 1994-1-1 [21]. The effects of creep, shrinkage and degree of shear connection on the deflection of simply supported composite beams are also analyzed. The long-term deflection calculated with the analytical model based on the rules given in EN 1994-1-1 [21] is compared against the one predicted by the proposed model. It is found that EN 1994-1-1 [21] slightly underestimate the long-term deflection. It was also observed that the contribution of shrinkage to the deflection is more significant than suggested in EN 1994-1-1 [21].     

The Seine system: introduction to a multidisciplinary approach of the functioning of a regional river system

The Seine basin (France) is dominated by the megalopolis of Paris (10 millions inhabitants), surrounded by intensive agricultural areas: it represents an important example of regional territory strongly affected by anthropogenic activity. In the scope of the PIREN-Seine program, an interdisciplinary study of this basin was conducted. This paper introduces a special issue of the Science of the Total Environment devoted to the results of this program. It summarizes the main features of the Seine river system, the physical characteristics of its drainage network and its watershed, and the nature and spatial distribution of human activities. The scientific approaches used for the study of the system are described, emphasizing the role of material budgeting, mathematical modeling and historical reconstruction. Some functional characteristics of the Seine watershed and drainage network are summarized, showing that the system is now essentially controlled by anthropogenic constraints.     

Biochemical,Enzymatic, and Computational Characterization of Recurrent Somatic Mutations of the Human Protein Tyrosine Phosphatase PTP1B in Primary Mediastinal B Cell Lymphoma

Human protein tyrosine phosphatase 1B (PTP1B) is a ubiquitous non-receptor tyrosine phosphatase that serves as a major negative regulator of tyrosine phosphorylation cascades of metabolic and oncogenic importance such as the insulin, epidermal growth factor receptor (EGFR), and JAK/STAT pathways. Increasing evidence point to a key role of PTP1B-dependent signaling in cancer. Interestingly, genetic defects in PTP1B have been found in different human malignancies. Notably, recurrent somatic mutations and splice variants of PTP1B were identified in human B cell and Hodgkin lymphomas. In this work, we analyzed the molecular and functional levels of three PTP1B mutations identified in primary mediastinal B cell lymphoma (PMBCL) patients and located in the WPD-loop (V184D), P-loop (R221G), and Q-loop (G259V). Using biochemical, enzymatic, and molecular dynamics approaches, we show that these mutations lead to PTP1B mutants with extremely low intrinsic tyrosine phosphatase activity that display alterations in overall protein stability and in the flexibility of the active site loops of the enzyme. This is in agreement with the key role of the active site loop regions, which are preorganized to interact with the substrate and to enable catalysis. Our study provides molecular and enzymatic evidence for the loss of protein tyrosine phosphatase activity of PTP1B active-site loop mutants identified in human lymphoma.     

On the confluence of ultrafast high-temperature sintering and flash sintering phenomena

Ultrafast high-temperature sintering (UHS) and flash sintering are novel methods for rapid sintering of ceramics, often completed in just a few seconds. Here, we show that both also share two additional features: an abrupt rise in electrical conductivity, which is electronic, and electroluminescence. More fundamentally, both are related to phonon physics where MD calculations have shown that proliferation of phonons at the edge of the Brillouin zone can induce Frenkel pairs without the application of electrical fields. Here, we show that, indeed, heating without the application of electric field, can also induce flash: Rapid heating processes of thin films of an oxide-salt deposited on silk fibers, with a propane torch, are shown to induce electronic conductivity, electroluminescence, and rapid sintering of the oxide. The discussion in this article harkens back to two inventions, more than a century ago, which can now be related to flash and UHS: (i) the Nernst glow lamp circa 1900, made from zirconia, and (ii) the Welsbach mantle, constituted from ceria doped thorium oxide, in the late nineteenth century. Thus, the confluence between high heating rate and electric field induced flash phenomena links the past to the new. The emerging question is how injection of phonons that has been shown to create Frenkels can further induce high electronic conductivity and electroluminescence in oxides. Both electronic conductivity and luminescence are likely related to the generation of electron–hole pairs.     

Tensile and water barrier properties of cassava starch composite films reinforced by synthetic zeolite and beidellite

Composites films were prepared by the casting method using native cassava starch plasticized with glycerol and 3D or 2D synthetic fillers i.e. Beta zeolite and Na-beidellite type 2:1 phyllosilicate. Special attention was paid to the effect of the filler contents and type on the mechanical and barrier properties. It was shown that films reinforced with lyophilized Beta zeolite presented both high water solubility (WS) and water vapor permeability (WVP) values than the pristine starch whereas an improvement on the WVP was found for composites prepared from Na-beidellite or from non lyophilized Beta zeolite. For the two types of fillers, a drastic increase of the mechanical properties (especially in the Young’s modulus) was observed.     

Advanced testing and debugging support for reactive executable DSLs

Software and Systems Modeling - Executable Domain-Specific Languages (xDSLs) allow the definition and the execution of behavioral models. Some behavioral models are reactive, meaning that during...