1,391 research outputs found

    Application of pactiter V3.3 code to the ACPS assessment of ITER neutral beam injectors primary heat transfer system

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    Activated Corrosion Products (ACPs) will be present in the various coolant loops of ITER: in-vessel and vacuum vessel, test blanket modules, auxiliary heating or diagnostic equipments. ACPs impact occupational exposure, routine effluents to the environment, and potential releases during accidents. Hence, the ACP inventory evaluation is an important task for ITER public and occupational safety. PACTITER v3.3 code is a computational tool derived from PACTOLE series of codes, modified in some modeling and computing capabilities. ITER Organization has included it as reference computer code for the ACP assessment. In the framework of its verification and validation activity, PACTITER v3.3 was used to assess the ACP inventory of the ITER Neutral Beam Injectors (NBIs) Primary Heat Transfer System (PHTS). This paper will document the preliminary results of this assessment, focusing on the impact of operation scenarios parameters (i.e. water chemistry, materials corrosion properties, etc.) and piping architecture

    Effects of garlic powder and salt on meat quality and microbial loads of rabbit burgers

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    The aim of the research study was to evaluate the effects of a common culinary spice such as garlic powder and salt addition on the quality and microbial shelf life of rabbit meat burgers. Rabbit burgers were evaluated for pH, the colour parameters, the water holding capacity and microbial loads during storage time of seven days at 4 ◦C. Four different formulations of burgers (n = 180 in total) were tested as control samples (only meat, C), burgers with garlic powder (at 0.25%, G), burgers with salt (at 1.00%, S) and burgers with both garlic powder and salt (0.25% and 1.00%, respectively, GS). As results, it was highlighted that garlic powder and salt addition significant affected pH, water holding capacity and some colour parameters of burgers. In particular, salt affected the pH of the raw burgers, leading to lower values that partially influenced all the colour parameters with higher a* values of S burgers. The mix of garlic powder and salt (GS burgers) showed mixed effects even if more closed to the G burgers than S ones. Salt expressed its properties of binding water molecules reducing drip and cooking losses in S and GS burgers. No variations in microbial loads were highlighted in relation to the formulations. Storage time affected all the parameters, highlighting a deterioration of the burgers' quality and an increase of the microbial loads

    Quantification of the effect of mammographic screening on fatal breast cancers: The Florence Programme 1990–96

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    Breast cancer cases diagnosed in women aged 50–69 since 1990 to 1996 in the City of Florence were partitioned into those who had been invited to screening prior to diagnosis and those who had not. All cases were followed up for vital status until 31 December 1999. The cumulative number of breast cancer deaths among the cases were divided by screening and invitation status, to give the rates of cancers proving fatal within a period of 8 years of observation (incidence-based mortality). We used the incidence-based mortality rates for two periods (1985–86, 1990–96), pre and during screening. The incidence-based mortality ratio comparing 1990–96 and 1985–86 was 0.50 (95% CI : 0.38–0.66), a significant 50% reduction. For noninvited women, compared to 1985-86, there was a 41% significant mortality reduction (RR=0.59, 95% CI : 0.42–0.82). The comparable reduction in those invited was a significant 55% (RR=0.45, 95% CI : 0.32–0.61). The incidence ratio of rates of cancers stage II or worse was close to one when the noninvited in 1990–96 were compared with 1985–86 (RR=0.97, 95% CI : 0.78–1.21). Excluding prevalent cases, the rate of stage II+ breast cancer cases was 42% lower in Screened women compared with the noninvited (RR=0.58, 95% CI : 0.45–0.74). This study confirmed that new treatments and the first rounds of the screening programme contributed to reducing mortality from breast cancer

    Gating of TonB-dependent transporters by substrate-specific forced remodelling

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    Membrane proteins play vital roles in inside-out and outside-in signal transduction by responding to inputs that include mechanical stimuli. Mechanical gating may be mediated by the membrane or by protein(s) but evidence for the latter is scarce. Here we use force spectroscopy, protein engineering and bacterial growth assays to investigate the effects of force on complexes formed between TonB and TonB-dependent transporters (TBDT) from Gram-negative bacteria. We confirm the feasibility of protein-only mediated mechanical gating by demonstrating that the interaction between TonB and BtuB (a TBDT) is sufficiently strong under force to create a channel through the TBDT. In addition, by comparing the dimensions of the force-induced channel in BtuB and a second TBDT (FhuA), we show that the mechanical properties of the interaction are perfectly tuned to their function by inducing formation of a channel whose dimensions are tailored to the ligand

    Mechanical response of random heteropolymers

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    We present an analytical theory for heteropolymer deformation, as exemplified experimentally by stretching of single protein molecules. Using a mean-field replica theory, we determine phase diagrams for stress-induced unfolding of typical random sequences. This transition is sharp in the limit of infinitely long chain molecules. But for chain lengths relevant to biological macromolecules, partially unfolded conformations prevail over an intermediate range of stress. These necklace-like structures, comprised of alternating compact and extended subunits, are stabilized by quenched variations in the composition of finite chain segments. The most stable arrangements of these subunits are largely determined by preferential extension of segments rich in solvophilic monomers. This predicted significance of necklace structures explains recent observations in protein stretching experiments. We examine the statistical features of select sequences that give rise to mechanical strength and may thus have guided the evolution of proteins that carry out mechanical functions in living cells.Comment: 10 pages, 6 figure

    Extracting Structural Information of a Heteropolymer from Force-Extension Curves

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    We present a theory for the reverse analysis on the sequence information of a single H/P two-letter random hetero-polymer (RHP) from its force-extension(f-z) curves during quasi static stretching. Upon stretching of a self-assembled RHP, it undergoes several structural transitions. The typical elastic response of a hetero-polymeric globule is a set of overlapping saw-tooth patterns. With consideration of the height and the position of the overlapping saw-tooth shape, we analyze the possibility of extracting the binding energies of the internal domains and the corresponding block sizes of the contributing conformations.Comment: 5 figures 7 page

    Equivalent Circuit for RF Flexural Free-Free MEMS Resonators

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    A method to extract a lumped-parameter equivalent circuit for a free-free flexural MEMS resonator, based on the Euler-Bernoulli beam equation and exploiting a modal analysis approach, is presented. The dynamic behaviour predicted by the equivalent circuit is compared with FEM simulations, and the effect of a geometrical mismatch is investigated as well. The resonance frequency and the quality factor are correctly predicted. The method could be used for more complex systems of interconnected beams. The circuit can be used as a quick and intuitive analysis tool for the system-level designer and to allow the simulation of the device in a system-level design environment

    Unraveling the molecular basis of subunit specificity in P pilus assembly by mass spectrometry

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    P pili are multisubunit fibers essential for the attachment of uropathogenic Escherichia coli to the kidney. These fibers are formed by the noncovalent assembly of six different homologous subunit types in an array that is strictly defined in terms of both the number and order of each subunit type. Assembly occurs through a mechanism termed “donor-strand exchange (DSE)” in which an N-terminal extension (Nte) of one subunit donates a β-strand to an adjacent subunit, completing its Ig fold. Despite structural determination of the different subunits, the mechanism determining specificity of subunit ordering in pilus assembly remained unclear. Here, we have used noncovalent mass spectrometry to monitor DSE between all 30 possible pairs of P pilus subunits and their Ntes. We demonstrate a striking correlation between the natural order of subunits in pili and their ability to undergo DSE in vitro. The results reveal insights into the molecular mechanism by which subunit ordering during the assembly of this complex is achieved

    MEAT QUALITY OF LOCAL AND HYBRID RABBITS

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    pH, colour and oxidative status were evaluated to study the effect of rabbit genotype on meat quality. Commercial Hybrids, selected for high growth rate and a local population, characterized by slow growing, were used. Meat quality characteristics of L. lumborum and B. femoris muscles showed significant differences between genotypes. Local population had higher pHu values but lower pH fall values than Hybrids. Hybrids showed higher lightness values and TBARS contents than local population. Meat quality parameters were influenced by genotype. The differences between genotypes could be related to the different degree of maturity because the rabbits, in relation to the different growth rate, were slaughtered at the same weight but at different age
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