113 research outputs found

    Effect of somatic cell count on milk composition and mozzarella cheese quality

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    The aim of this study was to investigate the effect of somatic cell count (SCC) on mozzarella cheese quality. Three categories of raw milk were selected: low (SCC 987 000 cells/ml). Cheeses were produced on the same day of milk collection and were vacuum packed in plastic bags and analysed weekly for 60 days at cold storage (4 Ā°C). As somatic cell count increases, casein content, casein as a percentage of true protein, lactose content, and titratable acidity decrease significantly in raw milk. No significant differences were observed in moisture, fat, and total protein contents among mozzarella cheese samples from the different SCC categories. However, cheese samples produced from high SCC milk had significantly higher pH (6.83) compared to samples produced with low and medium SCC milk, 5.58 and 5.46, respectively. The extension of proteolysis was not significant for cheese samples made from raw milk with low SCC during the first 30 days of cold storage. Proteolysis levels increased significantly on the 15th storage day for cheeses made with medium and high SCC, whereas significant increases were only observed on the 45th storage day for cheeses made with low SCC

    Experimental and numerical study on mechanical properties of aluminum alloy under uniaxial tensile test

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    The main objective is to model the behavior of 7075 aluminum alloy and built an experimental database to identify the model parameters. The first part of the paper presents an experimental database on 7075 aluminum alloy. Thus, uniaxial tensile tests are carried in three loading directions relative to the rolling direction, knowing that the fatigue of aircraft structures is traditionally managed based on the assumption of uniaxial loads. From experimental database, the mechanical properties are extracted, particularly the various fractures owing to pronounced anisotropy relating to material. In second part, plastic anisotropy is then modeled using the identification strategy which depends on yield criteria, hardening law and evolution law. In third part, a comparison with experimental data shows that behavior model can successfully describe the anisotropy of the Lankford coefficient

    Theorical study on mechanical properties of AZ31B Magnesium alloy Sheets under multiaxial loading

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    Numerical simulation by plastic deformation of the shaping processes currently has a large industrial interest. It allows you to shorten the time of design and construction related products and tools to analyze and to optimize processes. An essential part of simulation tools is the constitutive law used to describe the material used. The activity of characterization and modeling of material behavior of the plastic deformation shaping remains a very important research field of activity; the objective of proposing laws of behavior used in computer codes, essentially based on finite element is sufficiently to represent the real behavior of materials. Considering the nature of the materials used and the stresses they experience the behavior laws account for several requirements which make them increasingly complicated. Among these requirements, we cite in particular plastic anisotropy, the great transformations, the complexity and diversity of loads, etc. The complexity of these laws makes them more difficult to implement and in particular to identify: the classic tests are no longer sufficient for identification. The objective of this work is based on two essential points: Suggest a construction strategy, particularly of identifying laws elastoplastic behavior anisotropic operational for the numerical simulation of plastic deformation shaping processes with particular attention to sheet metal magnesium. Magnesium sheet metal manufacturing process involves rolling operation. In a cost-cutting goal, this operation now takes place cold, implying a very marked anisotropy of the material at the output of the mill.&nbsp

    Systematic Gene Overexpression in Candida albicans identifies a Regulator of Early Adaptation to the Mammalian Gut

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    We are grateful to members of the genomics core facility (PF2, GĆ©nopole) for the availability of the microarray scanner and the Alain Jacquierā€™s lab for making the GenePix software available. We are grateful to Drs. Suzanne Noble and Aaron Mitchell for providing C. albicans mutant collections. We thank all members of the Fungal Biology & Pathogenicity Unit, particularly Drs. Anne Neville and Adeline Feri for their numerous insights during the course of this project. This work has been supported by grants from the Agence Nationale de la Recherche (KANJI, ANR-08-MIE-033-01 to C.dā€™E. and F.D.; ERA-Net Infect-ERA, FUNCOMPATH, ANR-14-IFEC-0004; and CANDIHUB, ANR-14-CE-0018 to C.dā€™E.), the French Governmentā€™s Investissement dā€™Avenir program (Laboratoire dā€™Excellence Integrative Biology of Emerging Infectious Diseases, ANR-10-LABX-62-IBEID to C.dā€™E.; Institut de Recherche Technologique BIOASTER, ANR-10-AIRT-03 to C.dā€™E., F.D. and T.J.), the European Commission (FinSysB PITN-GA-2008-214004 to C.dā€™E.) and the Wellcome Trust (The Candida albicans ORFeome project, WT088858MA to C.dā€™E. and C.M.). C.M. acknowledges support from the Medical Research Council, UK (New Investigator Award, G0400284), the MRC Centre for Medical Mycology (MR/N006364/1) and the University of Aberdeen. S.Z. is an Institut Pasteur International Network Affiliate Program Fellow. S.Z., L.v.W. and A.H.C. were the recipients of post-doctoral fellowships from the European Commission (FINSysB, PITN-GA-2008-214004 to S.Z.), the Agence Nationale de la Recherche (KANJI, ANR-08-MIE-033-01 to S.Z.; ERA-Net Infect-ERA, FUNCOMPATH, ANR-14-IFEC-0004 to A.H.C.; CANDIHUB, ANR-14-CE-0018 to L.v.W) and the French Governmentā€™s Investissement dā€™Avenir program (Institut de Recherche Technologique BIOASTER, ANR-10-AIRT-03 to S.Z. and A.H.C.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

    Prediction of Phenotype-Associated Genes via a Cellular Network Approach: A Candida albicans Infection Case Study

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    Candida albicans is the most prevalent opportunistic fungal pathogen in humans causing superficial and serious systemic infections. The infection process can be divided into three stages: adhesion, invasion, and host cell damage. To enhance our understanding of these C. albicans infection stages, this study aimed to predict phenotype-associated genes involved during these three infection stages and their roles in C. albicansā€“host interactions. In light of the principles that proteins that lie closer to one another in a protein interaction network are more likely to have similar functions, and that genes regulated by the same transcription factors tend to have similar functions, a cellular network approach was proposed to predict the phenotype-associated genes in this study. A total of 4, 12, and 3 genes were predicted as adhesion-, invasion-, and damage-associated genes during C. albicans infection, respectively. These predicted genes highlight the facts that cell surface components are critical for cell adhesion, and that morphogenesis is crucial for cell invasion. In addition, they provide targets for further investigations into the mechanisms of the three C. albicans infection stages. These results give insights into the responses elicited in C. albicans during interaction with the host, possibly instrumental in identifying novel therapies to treat C. albicans infection

    The bZIP Transcription Factor Rca1p Is a Central Regulator of a Novel CO2 Sensing Pathway in Yeast

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    Like many organisms the fungal pathogen Candida albicans senses changes in the environmental CO2 concentration. This response involves two major proteins: adenylyl cyclase and carbonic anhydrase (CA). Here, we demonstrate that CA expression is tightly controlled by the availability of CO2 and identify the bZIP transcription factor Rca1p as the first CO2 regulator of CA expression in yeast. We show that Rca1p upregulates CA expression during contact with mammalian phagocytes and demonstrate that serine 124 is critical for Rca1p signaling, which occurs independently of adenylyl cyclase. ChIP-chip analysis and the identification of Rca1p orthologs in the model yeast Saccharomyces cerevisiae (Cst6p) point to the broad significance of this novel pathway in fungi. By using advanced microscopy we visualize for the first time the impact of CO2 build-up on gene expression in entire fungal populations with an exceptional level of detail. Our results present the bZIP protein Rca1p as the first fungal regulator of carbonic anhydrase, and reveal the existence of an adenylyl cyclase independent CO2 sensing pathway in yeast. Rca1p appears to regulate cellular metabolism in response to CO2 availability in environments as diverse as the phagosome, yeast communities or liquid culture

    A Human-Curated Annotation of the Candida albicans Genome

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    Recent sequencing and assembly of the genome for the fungal pathogen Candida albicans used simple automated procedures for the identification of putative genes. We have reviewed the entire assembly, both by hand and with additional bioinformatic resources, to accurately map and describe 6,354 genes and to identify 246 genes whose original database entries contained sequencing errors (or possibly mutations) that affect their reading frame. Comparison with other fungal genomes permitted the identification of numerous fungus-specific genes that might be targeted for antifungal therapy. We also observed that, compared to other fungi, the protein-coding sequences in the C. albicans genome are especially rich in short sequence repeats. Finally, our improved annotation permitted a detailed analysis of several multigene families, and comparative genomic studies showed that C. albicans has a far greater catabolic range, encoding respiratory Complex 1, several novel oxidoreductases and ketone body degrading enzymes, malonyl-CoA and enoyl-CoA carriers, several novel amino acid degrading enzymes, a variety of secreted catabolic lipases and proteases, and numerous transporters to assimilate the resulting nutrients. The results of these efforts will ensure that the Candida research community has uniform and comprehensive genomic information for medical research as well as for future diagnostic and therapeutic applications

    Identification strategy of anisotropic behavior laws: application to thin sheets of Aluminium A5

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    Numerical simulation provides a valuable assistance in the controlling of forming processes. The elasto-plastic orthotropic constitutive law is based on the choice of an equivalent stress, a hardening law and a plastic potential. An identification of the model parameters from an experimental database is developed. This database consists in hardening curves and Lankford coefficients of specimens subjected to off-axis tensile tests. The proposed identification strategy is applied to aluminum sheets. The behavior of this material is studied under several solicitations. The anisotropic behavior of the aluminum plate is modeled using the Barlat criterionand the hardening law. The obtained Lankford coefficients are compared to those which are identified by a different strategy
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