Molecular interactions and redox effects of carvacrol and thymol on myofibrillar proteins using a non-destructive and solvent-free methodological approach.

Science.gov (United States)

Lahmar, Aida; Akcan, Tolga; Chekir-Ghedira, Leila; Estévez, Mario

2018-04-01

The present study provides molecular insight into the effect of thymol and carvacrol on the oxidative damage caused to myofibrillar proteins by a hydroxyl-radical generating system (HRGS). An innovative model system was designed, in which gels, prepared with increasing levels of myofibrillar proteins, were oxidized by a HRGS (Fe 3+ /H 2 O 2 , 60 °C and 7 days) in the presence of lipids. The molecular affinity between myofibrillar proteins and both terpenes, as well as their effect on the oxidative stability of the gel systems, were studied using a non-destructive and solvent-free procedure based on fluorescence spectroscopy. Carvacrol displayed more affinity than thymol for establishing chemical interactions with protein residues. Both terpenes exhibited a significant antioxidant potential against the generation of lipid-derived volatile carbonyls and against the formation of protein crosslinking. This procedure may be applied to meat products to assess the effectiveness of a given antioxidant additive without size reduction or sample processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

Polyacrylamide gel electrophoresis-SDS as a tool to study myofibrillar proteins. A review.

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Perez-Chabela, M. Lourdes

2015-12-01

Full Text Available Miofibrillar proteins are part of land and sea animals’ muscle. Nonetheless, even when muscle proteins are the same type of proteins, their structure, rigor mortis time, and biochemical process associated to muscle to meat conversion, are different among animal species. This review has the aim to describe the advantages of SDS-polyacrylamide gel electrophoresis (SDS-PAGE in the study of myofibrillar proteins structure, besides the influence of many parameters on this technique to obtain an electrophoretic profile. Applications of this technique as a diagnostic tool in the food science, ecology and health are described as well.

Change of the structure and the digestibility of myofibrillar proteins in Nanjing dry-cured duck during processing.

Science.gov (United States)

Du, Xiaojing; Sun, Yangying; Pan, Daodong; Wang, Ying; Ou, Changrong; Cao, Jinxuan

2018-06-01

To investigate the change of bioavailability and structure of myofibrillar proteins during Nanjing dry-cured duck processing, carbonyl content, sulfhydryl (SH) group, disulfide (SS) group, sodium dodecyl sulfate polyacrylamide gel electrophoresis, surface hydrophobicity, secondary structures and in vitro digestibility were determined. During processing, carbonyl content and surface hydrophobicity increased; SH turned into SS group; α-helix turned into β-sheet and random coil fractions. Protein degradation occurred during dry-curing and drying-ripening stages. The in vitro digestibility of pepsin and pancreatic proteases increased during the salt curing stage and decreased during the drying-ripening stage. The increase of digestibility could be attributed to the mild oxidation, degradation and unfolding of proteins while the decrease of digestibility was related to the intensive oxidation and aggregation of proteins. Protein degradation was not a main factor of digestibility during the drying-ripening stage. Results demonstrated that the bioavailability loss of myofibrillar proteins in Nanjing dry-cured duck occurred during the stage of drying-ripening instead of curing. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Ca2+-dependent proteolytic activity in crab claw muscle: effects of inhibitors and specificity for myofibrillar proteins

International Nuclear Information System (INIS)

Mykles, D.L.; Skinner, D.M.

1983-01-01

The claw closer muscle of the Bermuda land crab, Gecarcinus lateralis, undergoes a sequential atrophy and restoration during each molting cycle. The role of Ca 2+ -dependent proteinases in the turn-over of myofibrillar protein in normal anecdysial (intermolt) claw muscle is described. Crab Ca 2+ -dependent proteinase degrades the myofibrillar proteins actin, myosin heavy and light chains, paramyosin, tropomyosin, and troponin-T and -I. Ca 2+ -dependent proteinase activity in whole homogenates and 90,000 x g supernatant fractions from muscle homogenates has been characterized with respect to Ca 2+ requirement, substrate specificity, and effects of proteinase inhibitors. The enzyme is inhibited by antipain, leupeptin, E-64, and iodoacetamide; it is insensitive to pepstatin A. The specificity of crab Ca 2+ -dependent proteinase was examined with native myosin with normal ATPase activity as well as with radioiodinated myosin and radioiodinated hemolymph proteins. Hydrolysis of 125 I-myosin occurs in two phases, both Ca 2+ -dependent: (1) heavy chain (M/sub r/ = 200,000) is cleaved into four large fragments (M/sub r/ = 160,000, 110,000, 73,000, 60,000) and numerous smaller fragments; light chain (M/sub r/ = 18,000) is cleaved to a 15,000-Da fragment; (2) the fragments produced in the first phase are hydrolyzed to acid-soluble material. Although radioiodinated native hemolymph proteins are not susceptible to the Ca 2+ -dependent proteinase, those denatured by carboxymethylation are degraded. These data suggest that crab Ca 2+ -dependent proteinase is involved in turnover of myofibrillar protein in normal muscle and muscle undergoing proecdysial atrophy

Filmes biodegradáveis à base de proteínas miofibrilares de pescado Biodegradable films based on myofibrillar proteins of fish

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Elessandra da Rosa Zavareze

2012-05-01

Full Text Available O objetivo deste trabalho foi estudar as propriedades físicas, mecânicas e de barreira dos filmes produzidos a partir de diferentes concentrações de proteínas miofibrilares de pescado de baixo valor comercial. O pescado utilizado foi a corvina (Micropogonias furnieri, que foi eviscerada e filetada. As proteínas miofibrilares foram obtidas do músculo, em sucessivas lavagens com água destilada. Os filmes foram produzidos com 3, 4 e 5% de proteínas miofibrilares pelo método de casting. Os filmes foram analisados nos seguintes aspectos: espessura, solubilidade, opacidade, resistência à tração, elongação e permeabilidade ao vapor de água (PVA. O aumento da concentração de proteínas miofibrilares atribuiu aos filmes maior espessura, opacidade, resistência à tração e PVA; no entanto, conferiu menor elongação na ruptura dos mesmos.The objective of this work was to study the physical, mechanical and barrier properties of the films produced from different concentrations of myofibrillar proteins of fish. The fish used was croaker (Micropogonias furnieri, which was gutted and filleted. The myofibrillar proteins were obtained through the muscle with successive washes with distilled water. The films were made with 3, 4 and 5% of myofibrillar proteins by the method of casting. The films were analyzed by thickness, solubility, opacity, tensile strength, elongation and water vapor permeability (PVA. The increase of myofibrillar proteins concentration in the films increased thickness, opacity, tensile strength and water vapor permeability and reduced elongation at break of the film.

Effect of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle.

Science.gov (United States)

Carter, W J; Van Der Weijden Benjamin, W S; Faas, F H

1980-10-01

Since experimental hyperthyroidism reduces skeletal muscle mass while simultaneously increasing cardiac muscle mass, the effect of hyperthyroidism on muscle protein degradation was compared in skeletal and cardiac muscle. Pulse-labeling studies using (3H) leucine and (14C) carboxyl labeled aspartate and glutamate were carried out. Hyperthyroidism caused a 25%-29% increase in protein breakdown in both sarcoplasmic and myofibrillar fractions of skeletal muscle. Increased muscle protein degradation may be a major factor in the development of skeletal muscle wasting and weakness in hyperthyroidism. In contrast, protein breakdown appeared to be reduced 22% in the sarcoplasmic fraction of hyperthyroid heart muscle and was unchanged in the myofibrillar fraction. Possible reasons for the contrasting effects of hyperthyroidism on skeletal and cardiac muscle include increased sensitivity of the hyperthyroid heart to catecholamines, increased cardiac work caused by the hemodynamic effects of hyperthyroidism, and a different direct effect of thyroid hormone at the nuclear level in cardiac as opposed to skeletal muscle.

Zebrafish models of BAG3 myofibrillar myopathy suggest a toxic gain of function leading to BAG3 insufficiency.

Science.gov (United States)

Ruparelia, Avnika A; Oorschot, Viola; Vaz, Raquel; Ramm, Georg; Bryson-Richardson, Robert J

2014-12-01

Mutations in the co-chaperone Bcl2-associated athanogene 3 (BAG3) can cause myofibrillar myopathy (MFM), a childhood-onset progressive muscle disease, characterized by the formation of protein aggregates and myofibrillar disintegration. In contrast to other MFM-causing proteins, BAG3 has no direct structural role, but regulates autophagy and the degradation of misfolded proteins. To investigate the mechanism of disease in BAG3-related MFM, we expressed wild-type BAG3 or the dominant MFM-causing BAG3 (BAG3(P209L)) in zebrafish. Expression of the mutant protein results in the formation of aggregates that contain wild-type BAG3. Through the stimulation and inhibition of autophagy, we tested the prevailing hypothesis that impaired autophagic function is responsible for the formation of protein aggregates. Contrary to the existing theory, our studies reveal that inhibition of autophagy is not sufficient to induce protein aggregation. Expression of the mutant protein, however, did not induce myofibrillar disintegration and we therefore examined the effect of knocking down Bag3 function. Loss of Bag3 resulted in myofibrillar disintegration, but not in the formation of protein aggregates. Remarkably, BAG3(P209L) is able to rescue the myofibrillar disintegration phenotype, further demonstrating that its function is not impaired. Together, our knockdown and overexpression experiments identify a mechanism whereby BAG3(P209L) aggregates form, gradually reducing the pool of available BAG3, which eventually results in BAG3 insufficiency and myofibrillar disintegration. This mechanism is consistent with the childhood onset and progressive nature of MFM and suggests that reducing aggregation through enhanced degradation or inhibition of nucleation would be an effective therapy for this disease.

Polymorphism of myofibrillar proteins of rabbit skeletal-muscle fibres. An electrophoretic study of single fibres.

OpenAIRE

Salviati, G; Betto, R; Danieli Betto, D

1982-01-01

Rabbit predominantly fast-twitch-fibre and predominantly slow-twitch-fibre skeletal muscles of the hind limbs, the psoas, the diaphragm and the masseter muscles were fibre-typed by one-dimensional polyacrylamide-gel electrophoresis of the myofibrillar proteins of chemically skinned single fibres. Investigation of the distribution of fast-twitch-fibre and slow-twitch-fibre isoforms of myosin light chains and the type of myosin heavy chains, based on peptide 'maps' published in Cleveland. Fisch...

Water binding of proteins in the processing frankfurter-type sausages. Part. 1. Water-binding ability of freeze-dried meat fractions containing myofibrillar and stromal proteins.

Science.gov (United States)

Heinevetter, L; Gassmann, B; Kroll, J

1987-01-01

As soon as possible and 48 h after slaughter respectively, from both blade-bone muscle groups of cattle and pig carcasses the "thick pieces" were excised, extracted, and fractionated. Residues and precipitates from water and salt extracts resulted were freeze-dried, and an improved Baumann capillary suction apparatus was used to measure their water binding capacity (WBC) with and without addition of 2% sodium chloride and/or heating to 80 degrees C. With one exception the WBC results followed a relative pattern demonstrating the final residues (stromal proteins and leavings of myofibrillar proteins) binding the highest amount of added water, precipitates of dialysis (mainly containing myofibrillar proteins) a remarkable amount and powdered meats the least. As scanning electron micrographs confirmed, there were no fibrous structures in the precipitates resulted from dialysis of salt solutions (1.0 mol/1). Heating decreased the spontaneous water uptake of all fractions. Addition of sodium chloride had only a noticeable capillary-suction and swelling effect on unheated samples. Hence swelling of undissolved protein structures (extraction of myosin and possibly of actomyosin) is therefore not the only way for water binding in frankfurter-type sausages.

Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men.

Science.gov (United States)

Mitchell, Cameron J; Churchward-Venne, Tyler A; Parise, Gianni; Bellamy, Leeann; Baker, Steven K; Smith, Kenneth; Atherton, Philip J; Phillips, Stuart M

2014-01-01

Muscle hypertrophy following resistance training (RT) involves activation of myofibrillar protein synthesis (MPS) to expand the myofibrillar protein pool. The degree of hypertrophy following RT is, however, highly variable and thus we sought to determine the relationship between the acute activation of MPS and RT-induced hypertrophy. We measured MPS and signalling protein activation after the first session of resistance exercise (RE) in untrained men (n = 23) and then examined the relation between MPS with magnetic resonance image determined hypertrophy. To measure MPS, young men (24±1 yr; body mass index  = 26.4±0.9 kg•m²) underwent a primed constant infusion of L-[ring-¹³C₆] phenylalanine to measure MPS at rest, and acutely following their first bout of RE prior to 16 wk of RT. Rates of MPS were increased 235±38% (Pmuscle volume and acute rates of MPS measured over 1-3 h (r = 0.02), 3-6 h (r = 0.16) or the aggregate 1-6 h post-exercise period (r = 0.10). Hypertrophy after chronic RT was correlated (r = 0.42, P = 0.05) with phosphorylation of 4E-BP1(Thr37/46) at 1 hour post RE. We conclude that acute measures of MPS following an initial exposure to RE in novices are not correlated with muscle hypertrophy following chronic RT.

The Study of Effect of Surimi Production Steps on Chemical Composition and Electrophoresis Pattern of Myofibrillar Proteins of Mechanically Deboned poultry meat (MDPM

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Sh Haji BagherNaeeni

2013-08-01

Full Text Available Mechanically deboning poultry meat (MDPM is widely used due to its suitable technological properties as well as low lipids and saturated fatty acids contents. Besides, production processes applied during the surimi production can improve the technological properties of MDPM. That is to say, the production steps of surimi can change chemical composition and concentration of myofibrillar proteins and improve functional properties of MDPM. In this study, MDPM was prepared from the poultry meat. The production process consisted of 2 washing steps with sodium bicarbonate solution followed by another washing step with 4°C water. Afterwards, chemical properties of MDPM and surimi (moisture content, protein, lipid, and ash content as well as electrophoresis pattern were evaluated. Result showed that surimi production steps could significantly decrease protein, lipid and ash contents; however, moisture content of MDPM increased significantly. The result of electrophoresis indicated a significant increase in heavy chain myosin with 200 KDa and actin with 45 KDa molecular weights. It was concluded that the production steps improved the chemical properties and increased the concentration of MDPM myofibrillar proteins.

Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis

DEFF Research Database (Denmark)

Doessing, Simon; Heinemeier, Katja M; Holm, Lars

2010-01-01

young individuals. rhGH administration caused an increase in serum GH, serum IGF-I, and IGF-I mRNA expression in tendon and muscle. Tendon collagen I mRNA expression and tendon collagen protein synthesis increased by 3.9-fold and 1.3-fold, respectively (P ...RNA expression and muscle collagen protein synthesis increased by 2.3-fold and 5.8-fold, respectively (P protein synthesis was unaffected by elevation of GH and IGF-I. Moderate exercise did not enhance the effects of GH manipulation. Thus, increased GH availability stimulates...... matrix collagen synthesis in skeletal muscle and tendon, but without any effect upon myofibrillar protein synthesis. The results suggest that GH is more important in strengthening the matrix tissue than for muscle cell hypertrophy in adult human musculotendinous tissue....

Intracellular protein breakdown. 8

International Nuclear Information System (INIS)

Bohley, P.; Kirschke, H.; Langner, J.; Wiederanders, B.; Ansorge, S.

1976-01-01

Double-labelled proteins from rat liver cytosol ( 14 C in long-lived, 3 H in short-lived proteins after in-vivo-labelling) are used as substrates for unlabelled proteinases in vitro. Differences in the degradation rates of short-lived and long-lived proteins in vitro by different proteinases and after addition of different effectors allow conclusions concerning their importance for the in-vivo-turnover of substrate proteins. The main activity (>90%) of soluble lysosomal proteinases at pH 6.1 and pH 6.9 is caused by thiolproteinases, which degrade preferentially short-lived cytosol proteins. These proteinases are inhibited by leupeptin. Autolysis of double-labelled cell fractions shows a remarkably faster breakdown of short-lived substrate proteins only in the soluble part of lysosomes. Microsomal fractions degrade in vitro preferentially long-lived substrate proteins. (author)

Cardiac myofibrillar contractile properties during the progression from hypertension to decompensated heart failure.

Science.gov (United States)

Hanft, Laurin M; Emter, Craig A; McDonald, Kerry S

2017-07-01

Heart failure arises, in part, from a constellation of changes in cardiac myocytes including remodeling, energetics, Ca 2+ handling, and myofibrillar function. However, little is known about the changes in myofibrillar contractile properties during the progression from hypertension to decompensated heart failure. The aim of the present study was to provide a comprehensive assessment of myofibrillar functional properties from health to heart disease. A rodent model of uncontrolled hypertension was used to test the hypothesis that myocytes in compensated hearts exhibit increased force, higher rates of force development, faster loaded shortening, and greater power output; however, with progression to overt heart failure, we predicted marked depression in these contractile properties. We assessed contractile properties in skinned cardiac myocyte preparations from left ventricles of Wistar-Kyoto control rats and spontaneous hypertensive heart failure (SHHF) rats at ~3, ~12, and >20 mo of age to evaluate the time course of myofilament properties associated with normal aging processes compared with myofilaments from rats with a predisposition to heart failure. In control rats, the myofilament contractile properties were virtually unchanged throughout the aging process. Conversely, in SHHF rats, the rate of force development, loaded shortening velocity, and power all increased at ~12 mo and then significantly fell at the >20-mo time point, which coincided with a decrease in left ventricular fractional shortening. Furthermore, these changes occurred independent of changes in β-myosin heavy chain but were associated with depressed phosphorylation of myofibrillar proteins, and the fall in loaded shortening and peak power output corresponded with the onset of clinical signs of heart failure. NEW & NOTEWORTHY This novel study systematically examined the power-generating capacity of cardiac myofilaments during the progression from hypertension to heart disease. Previously

Effect of resistance training and protein intake pattern on myofibrillar protein synthesis and proteome kinetics in older men in energy restriction.

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Murphy, Caoileann H; Shankaran, Mahalakshmi; Churchward-Venne, Tyler A; Mitchell, Cameron J; Kolar, Nathan M; Burke, Louise M; Hawley, John A; Kassis, Amira; Karagounis, Leonidas G; Li, Kelvin; King, Chelsea; Hellerstein, Marc; Phillips, Stuart M

2018-06-01

Strategies to enhance the loss of fat while preserving muscle mass during energy restriction are of great importance to prevent sarcopenia in overweight older adults. We show for the first time that the integrated rate of synthesis of numerous individual contractile, cytosolic and mitochondrial skeletal muscle proteins was increased by resistance training (RT) and unaffected by dietary protein intake pattern during energy restriction in free-living, obese older men. We observed a correlation between the synthetic rates of skeletal muscle-derived proteins obtained in serum (creatine kinase M-type, carbonic anhydrase 3) and the synthetic rates of proteins obtained via muscle sampling; and that the synthesis rates of these proteins in serum revealed the stimulatory effects of RT. These results have ramifications for understanding the influence of RT on skeletal muscle and are consistent with the role of RT in maintaining muscle protein synthesis and potentially supporting muscle mass preservation during weight loss. We determined how the pattern of protein intake and resistance training (RT) influenced longer-term (2 weeks) integrated myofibrillar protein synthesis (MyoPS) during energy restriction (ER). MyoPS and proteome kinetics were measured during 2 weeks of ER alone and 2 weeks of ER plus RT (ER + RT) in overweight/obese older men. Participants were randomized to consume dietary protein in a balanced (BAL: 25% daily protein per meal × 4 meals) or skewed (SKEW: 7:17:72:4% daily protein per meal) pattern (n = 10 per group). Participants ingested deuterated water during the consecutive 2-week periods, and skeletal muscle biopsies and serum were obtained at the beginning and conclusion of ER and ER + RT. Bulk MyoPS (i.e. synthesis of the myofibrillar protein sub-fraction) and the synthetic rates of numerous individual skeletal muscle proteins were quantified. Bulk MyoPS was not affected by protein distribution during ER or ER + RT (ER: BAL = 1.24�

Potential Biomarker of Myofibrillar Protein Oxidation in Raw and Cooked Ham: 3-Nitrotyrosine Formed by Nitrosation.

Science.gov (United States)

Feng, Xianchao; Li, Chenyi; Ullah, Niamat; Hackman, Robert M; Chen, Lin; Zhou, Guanghong

2015-12-30

The stability of cured meat products is increased by the protection of its proteins from oxidation by sodium nitrite (NaNO2) during processing. This study investigated the effects of NaNO2 (0, 50, 100, 200, and 400 mg/kg) on the physiochemical and structural characteristics of myofibrillar protein (MP) in raw and cooked ham. The NaNO2 showed a dose-dependent antioxidant effect, by inhibiting carbonyl formation, dityrosine formation, and denaturation of MP, and a nitrosative effect, through the formation of 3-Nitrotyrosine (3-NT). The 3-NT content within MP of raw ham had distinct negative correlations with sulfhydryl content and surface hydrophobicity. The 3-NT content within MP of cooked ham had significantly negative correlations with carbonyl, sulfhydryl content and turbidity and had significantly positive correlations with disulfide content. These results indicated that 3-NT may be a potential marker for protein oxidation in raw and cooked cured meat products.

Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men.

Directory of Open Access Journals (Sweden)

Cameron J Mitchell

Full Text Available Muscle hypertrophy following resistance training (RT involves activation of myofibrillar protein synthesis (MPS to expand the myofibrillar protein pool. The degree of hypertrophy following RT is, however, highly variable and thus we sought to determine the relationship between the acute activation of MPS and RT-induced hypertrophy. We measured MPS and signalling protein activation after the first session of resistance exercise (RE in untrained men (n = 23 and then examined the relation between MPS with magnetic resonance image determined hypertrophy. To measure MPS, young men (24±1 yr; body mass index  = 26.4±0.9 kg•m² underwent a primed constant infusion of L-[ring-¹³C₆] phenylalanine to measure MPS at rest, and acutely following their first bout of RE prior to 16 wk of RT. Rates of MPS were increased 235±38% (P<0.001 above rest 60-180 min post-exercise and 184±28% (P = 0.037 180-360 min post exercise. Quadriceps volume increased 7.9±1.6% (-1.9-24.7% (P<0.001 after training. There was no correlation between changes in quadriceps muscle volume and acute rates of MPS measured over 1-3 h (r = 0.02, 3-6 h (r = 0.16 or the aggregate 1-6 h post-exercise period (r = 0.10. Hypertrophy after chronic RT was correlated (r = 0.42, P = 0.05 with phosphorylation of 4E-BP1(Thr37/46 at 1 hour post RE. We conclude that acute measures of MPS following an initial exposure to RE in novices are not correlated with muscle hypertrophy following chronic RT.

Rheological Enhancement of Pork Myofibrillar Protein-Lipid Emulsion Composite Gels via Glucose Oxidase Oxidation/Transglutaminase Cross-Linking Pathway.

Science.gov (United States)

Wang, Xu; Xiong, Youling L; Sato, Hiroaki

2017-09-27

Porcine myofibrillar protein (MP) was modified with glucose oxidase (GluOx)-iron that produces hydroxyl radicals then subjected to microbial transglutaminase (TGase) cross-linking in 0.6 M NaCl at 4 °C. The resulting aggregation and gel formation of MP were examined. The GluOx-mediated oxidation promoted the formation of both soluble and insoluble protein aggregates via disulfide bonds and occlusions of hydrophobic groups. The subsequent TGase treatment converted protein aggregates into highly cross-linked polymers. MP-lipid emulsion composite gels formed with such polymers exhibited markedly enhanced gelling capacity: up to 4.4-fold increases in gel firmness and 3.5-fold increases in gel elasticity over nontreated protein. Microstructural examination showed small oil droplets dispersed in a densely packed gel matrix when MP was oxidatively modified, and the TGase treatment further contributed to such packing. The enzymatic GluOx oxidation/TGase treatment shows promise to improve the textural properties of emulsified meat products.

Controlled formation of emulsion gels stabilized by salted myofibrillar protein under malondialdehyde (MDA)-induced oxidative stress.

Science.gov (United States)

Zhou, Feibai; Sun, Weizheng; Zhao, Mouming

2015-04-15

This study presented the cold-set gelation of emulsions stabilized by salted myofibrillar protein (MP) under oxidative stress originated from malondialdehyde (MDA). Gel properties were compared over a range of MDA/NaCl concentrations including gel viscoelastic properties, strength, water-holding capacity (WHC), amount of protein entrapped, and microstructure. The oxidative stability of emulsion gels as indicated by lipid hydroperoxide was further determined and compared. Results indicated that emulsion stabilized by MP at swollen state under certain ionic strengths (0.2-0.6 M) was the premise of gel formation under MDA. In the presence of intermediate MDA concentrations (2.5-10 mM), the emulsion gels showed an improved elasticity, strength, WHC, and oxidative stability. This improvement should be mainly attributed to the enhanced protein-protein cross-linkings via MDA, which were homogeneously formed among absorbed and/or unabsorbed proteins, entrapping a greater amount and fractions of protein within network. Therefore, the oil droplets were better adherent to the gel matrix. Nevertheless, addition of high MDA concentrations (25-50 mM) led to the formation of excessive covalent bonds, which might break protein-protein bonds and trigger the desorption of protein from the interface. This ultimately caused "oil leak" phenomena as well as the collapse of gel structure and, thus, overall decreased gel properties and oxidative stability.

Myofibrillar protein synthesis following ingestion of soy protein isolate at rest and after resistance exercise in elderly men

Directory of Open Access Journals (Sweden)

Yang Yifan

2012-06-01

Full Text Available Abstract Background Increased amino acid availability stimulates muscle protein synthesis, however, aged muscle appears less responsive to the anabolic effects of amino acids when compared to the young. We aimed to compare changes in myofibrillar protein synthesis (MPS in elderly men at rest and after resistance exercise following ingestion of different doses of soy protein and compare the responses to those we previously observed with ingestion of whey protein isolate. Methods Thirty elderly men (age 71 ± 5 y completed a bout of unilateral knee-extensor resistance exercise prior to ingesting no protein (0 g, or either 20 g or 40 g of soy protein isolate (0, S20, and S40 respectively. We compared these responses to previous responses from similar aged men who had ingested 20 g and 40 g of whey protein isolate (W20 and W40. A primed constant infusion of L-[1-13 C]leucine and L-[ring-13 C6]phenylalanine and skeletal muscle biopsies were used to measure whole-body leucine oxidation and MPS over 4 h post-protein consumption in both exercised and non-exercised legs. Results Whole-body leucine oxidation increased with protein ingestion and was significantly greater for S20 vs. W20 (P = 0.003. Rates of MPS for S20 were less than W20 (P = 0.02 and not different from 0 g (P = 0.41 in both exercised and non-exercised leg muscles. For S40, MPS was also reduced compared with W40 under both rested and post-exercise conditions (both P P = 0.04. Conclusions The relationship between protein intake and MPS is both dose and protein source-dependent, with isolated soy showing a reduced ability, as compared to isolated whey protein, to stimulate MPS under both rested and post-exercise conditions. These differences may relate to the lower postprandial leucinemia and greater rates of amino acid oxidation following ingestion of soy versus whey protein.

Whey protein supplementation preserves postprandial myofibrillar protein synthesis during short-term energy restriction in overweight and obese adults.

Science.gov (United States)

Hector, Amy J; Marcotte, George R; Churchward-Venne, Tyler A; Murphy, Caoileann H; Breen, Leigh; von Allmen, Mark; Baker, Steven K; Phillips, Stuart M

2015-02-01

Higher dietary energy as protein during weight loss results in a greater loss of fat mass and retention of muscle mass; however, the impact of protein quality on the rates of myofibrillar protein synthesis (MPS) and lipolysis, processes that are important in the maintenance of muscle and loss of fat, respectively, are unknown. We aimed to determine how the consumption of different sources of proteins (soy or whey) during a controlled short-term (14-d) hypoenergetic diet affected MPS and lipolysis. Men (n = 19) and women (n = 21) (age 35-65 y; body mass index 28-50 kg/m(2)) completed a 14-d controlled hypoenergetic diet (-750 kcal/d). Participants were randomly assigned, double blind, to receive twice-daily supplements of isolated whey (27 g/supplement) or soy (26 g/supplement), providing a total protein intake of 1.3 ± 0.1 g/(kg · d), or isoenergetic carbohydrate (25 g maltodextrin/supplement) resulting in a total protein intake of 0.7 ± 0.1 g/(kg · d). Before and after the dietary intervention, primed continuous infusions of L-[ring-(13)C6] phenylalanine and [(2)H5]-glycerol were used to measure postabsorptive and postprandial rates of MPS and lipolysis. Preintervention, MPS was stimulated more (P whey than with soy or carbohydrate. Postintervention, postabsorptive MPS decreased similarly in all groups (all P whey group, which was less (P whey. We conclude that whey protein supplementation attenuated the decline in postprandial rates of MPS after weight loss, which may be of importance in the preservation of lean mass during longer-term weight loss interventions. This trial was registered at clinicaltrials.gov as NCT01530646. © 2015 American Society for Nutrition.

Skeletal Muscle Myofibrillar and Sarcoplasmic Protein Synthesis Rates Are Affected Differently by Altitude-Induced Hypoxia in Native Lowlanders

DEFF Research Database (Denmark)

Holm, Lars; Lyhne Haslund, Mads; Robach, Paul

2010-01-01

As a consequence to hypobaric hypoxic exposure skeletal muscle atrophy is often reported. The underlying mechanism has been suggested to involve a decrease in protein synthesis in order to conserve O(2). With the aim to challenge this hypothesis, we applied a primed, constant infusion of 1-(13)C...... and expired breath samples were collected hourly during the 4 hour trial and vastus lateralis muscle biopsies obtained at 1 and 4 hours after tracer priming in the overnight fasted state. Myofibrillar protein synthesis rate was doubled; 0.041±0.018 at sea-level to 0.080±0.018%⋅hr(-1) (p0.05). Trends...... to increments in whole body protein kinetics were seen: Degradation rate elevated from 2.51±0.21 at sea level to 2.73±0.13 µmol⋅kg(-1)⋅min(-1) (p = 0.05) at high altitude and synthesis rate similar; 2.24±0.20 at sea level and 2.43±0.13 µmol⋅kg(-1)⋅min(-1) (p>0.05) at altitude. We conclude that whole body amino...

Solubilization of myofibrillar proteins in water or low ionic strength media: Classical techniques, basic principles, and novel functionalities.

Science.gov (United States)

Chen, Xing; Tume, Ron K; Xu, Xinglian; Zhou, Guanghong

2017-10-13

The qualitative characteristics of meat products are closely related to the functionality of muscle proteins. Myofibrillar proteins (MPs), comprising approximately 50% of total muscle proteins, are generally considered to be insoluble in solutions of low ionic strength ( 0.3 M) for solubilization. These soluble proteins are the ones which determine many functional properties of meat products, including emulsification and thermal gelation. In order to increase the utilization of meat and meat products, many studies have investigated the solubilization of MPs in water or low ionic strength media and determining their functionality. However, there still remains a lack of systematic information on the functional properties of MPs solubilized in this manner. Hence, this review will explore some typical techniques that have been used. The main procedures used for their solubilization, the fundamental principles and their functionalities in water (low ionic strength medium) are comprehensively discussed. In addition, advantages and disadvantages of each technique are summarized. Finally, future considerations are presented to facilitate progress in this new area and to enable water soluble muscle MPs to be utilized as novel meat ingredients in the food industry.

Differential saliva-induced breakdown of starch filled protein gels in relation to sensory perception

NARCIS (Netherlands)

Janssen, A.M.; Pijpekamp, A.M. van de; Labiausse, D.

2009-01-01

In this study, the differential breakdown of protein gels containing four types of high and low cross-linked starch granules were studied. Susceptibility to saliva-induced breakdown of starch granules and the consequences of these for overall breakdown of the gel matrix were captured using a

Emulsion properties of pork myofibrillar protein in combination with microbial transglutaminase and calcium alginate under various pH conditions.

Science.gov (United States)

Hong, Geun Pyo; Min, Sang-Gi; Chin, Koo Bok

2012-01-01

In this study, the effects of microbial transglutaminase (MTG) and calcium alginate (CA) systems in combination with soybean oil on the emulsion properties of porcine myofibrillar protein (MP) were evaluated under various pH conditions. MTG was shown to improve emulsifying capacity and creaming stability, which increased with increasing pH values up to 6.5. The CA did not influence emulsifying capacity, but it improved the creaming stability of the MP-stabilized emulsions. Both MTG and CA enhanced the rheological properties, but their effects on the physical characteristics of the protein evidenced an opposite trend in relation to pH, i.e., the MTG system improved both the emulsion and gelling properties with increasing pH, whereas the CA system was effective when the pH was lowered. By combining the two MP gelling systems, a stable and pH-insensible emulsion could be produced. Copyright © 2011 Elsevier Ltd. All rights reserved.

Masseter muscle myofibrillar protein synthesis and degradation in an experimental critical illness myopathy model.

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Hazem Akkad

Full Text Available Critical illness myopathy (CIM is a debilitating common consequence of modern intensive care, characterized by severe muscle wasting, weakness and a decreased myosin/actin (M/A ratio. Limb/trunk muscles are primarily affected by this myopathy while cranial nerve innervated muscles are spared or less affected, but the mechanisms underlying these muscle-specific differences remain unknown. In this time-resolved study, the cranial nerve innervated masseter muscle was studied in a unique experimental rat intensive care unit (ICU model, where animals were exposed to sedation, neuromuscular blockade (NMB, mechanical ventilation, and immobilization for durations varying between 6 h and 14d. Gel electrophoresis, immunoblotting, RT-PCR and morphological staining techniques were used to analyze M/A ratios, myofiber size, synthesis and degradation of myofibrillar proteins, and levels of heat shock proteins (HSPs. Results obtained in the masseter muscle were compared with previous observations in experimental and clinical studies of limb muscles. Significant muscle-specific differences were observed, i.e., in the masseter, the decline in M/A ratio and muscle fiber size was small and delayed. Furthermore, transcriptional regulation of myosin and actin synthesis was maintained, and Akt phosphorylation was only briefly reduced. In studied degradation pathways, only mRNA, but not protein levels of MuRF1, atrogin-1 and the autophagy marker LC3b were activated by the ICU condition. The matrix metalloproteinase MMP-2 was inhibited and protective HSPs were up-regulated early. These results confirm that the cranial nerve innervated masticatory muscles is less affected by the ICU-stress response than limb muscles, in accordance with clinical observation in ICU patients with CIM, supporting the model' credibility as a valid CIM model.

Comparison of myofibrillar protein degradation, antioxidant profile, fatty acids, metmyoglobin reducing activity, physicochemical properties and sensory attributes of gluteus medius and infraspinatus muscles in goats

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Kazeem D. Adeyemi

2016-06-01

Full Text Available Abstract Background The functionality of myofibrillar proteins is a major factor influencing the quality attributes of muscle foods. Nonetheless, the relationships between muscle type and oxidative changes in chevon during ageing are meagrely elucidated. Postmortem changes in antioxidant status and physicochemical properties of glycolytic gluteus medius (GM and oxidative infraspinatus (IS muscles in goats were compared. Methods Twenty Boer bucks (9–10 months old, body weight of 36.9 ± 0.725 kg were slaughtered and the carcasses were subjected to chill storage (4 ± 0.5 °C. Analyses were conducted on GM and IS muscles sampled on 0, 1, 4 and 7 d postmortem. Results Chill storage did not affect the antioxidant enzyme activities in both muscles. The IS had greater (P  0.05 on free thiol, MRA and TBARS. The GM had lower (P  0.05 on consumer preference for flavour, juiciness and overall acceptability. However, IS had higher (P < 0.05 tenderness score than GM on d 1 and 4 postmortem. Intramuscular fat was higher (P < 0.05 in IS compared with GM. Fatty acid composition did not differ between the muscles. However, GM had lower (P < 0.05 n-6/n-3 ratio than IS. The n-3 and n-6 PUFA declined (P < 0.05 while the SFA increased (P < 0.05 over storage. Conclusion The changes in myofibrillar proteins and physicochemical properties of goat meat during postmortem chill storage are muscle-dependent.

Preparo e caracterização de proteínas miofibrilares de tilápia-do-nilo para elaboração de biofilmes Extraction and properties of nile tilapia myofibrillar proteins for edible films

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Ednelí Soraya Monterrey-Quintero

2000-01-01

Full Text Available A elaboração de filmes comestíveis à base de biopolímeros implica conhecimento das propriedades físico-químicas da macromolécula. Os objetivos deste trabalho foram a descrição de um método de preparo de proteínas miofibrilares de tilápia-do-nilo (Oreochromis niloticus, o estudo das propriedades relacionadas com a formação de filmes, e a caracterização dos biofilmes elaborados com a proteína. Músculo moído de tilápia-do-nilo, recém-abatida, foi lavado e processado até formação de uma pasta homogênea. A evolução das frações protéicas, durante o processamento, foi acompanhada por calorimetria diferencial de varredura. Estudou-se a solubilidade das proteínas miofibrilares liofilizadas (PML em função do pH (2-7. A identificação das frações protéicas e dos aminoácidos foi realizada por SDS-PAGE e cromatografia de troca iônica, respectivamente. Os biofilmes formados foram submetidos a testes de perfuração, de solubilidade e microscopia eletrônica. A amostra de PML, constituída apenas de proteínas miofibrilares, apresentou uma região de máxima solubilidade (96,9% em torno do pH 3,0 e elevado potencial de interações iônicas (74,4 kJ/100 kJ. Os biofilmes à base das PML de tilápia-do-nilo são pouco solúveis (abaixo de 20 g/100 g matéria seca. O glicerol influencia fortemente as propriedades mecânicas e a solubilidade dos biofilmes.The elaboration of edible films based on biopolymers, implies the knowledge of physicochemical properties of macromolecules. The objectives of this work were to describe a methodology of preparing Nile Tilapia myofibrillar proteins and study the properties related to formation and characterization of edible film elaborated with these proteins. Freshly slaughtered ground Nile Tilapia (Oreochromis niloticus muscle was washed and processed until the formation of a homogeneous paste. Evolution of protein fractions during processing was followed by scanning differential

Determination of steady-state protein breakdown rate in vivo by the disappearance of protein-bound tracer-labeled amino acids

DEFF Research Database (Denmark)

Holm, Lars; O'Rourke, Bruce; Ebenstein, David

2013-01-01

A method to determine the rate of protein breakdown in individual proteins was developed and tested in rats and confirmed in humans, using administration of deuterium oxide and incorporation of the deuterium into alanine that was subsequently incorporated into body proteins. Measurement of the fr...

BAG3 myofibrillar myopathy presenting with cardiomyopathy.

Science.gov (United States)

Konersman, Chamindra G; Bordini, Brett J; Scharer, Gunter; Lawlor, Michael W; Zangwill, Steven; Southern, James F; Amos, Louella; Geddes, Gabrielle C; Kliegman, Robert; Collins, Michael P

2015-05-01

Myofibrillar myopathies (MFMs) are a heterogeneous group of neuromuscular disorders distinguished by the pathological hallmark of myofibrillar dissolution. Most patients present in adulthood, but mutations in several genes including BCL2-associated athanogene 3 (BAG3) cause predominantly childhood-onset disease. BAG3-related MFM is particularly severe, featuring weakness, cardiomyopathy, neuropathy, and early lethality. While prior cases reported either neuromuscular weakness or concurrent weakness and cardiomyopathy at onset, we describe the first case in which cardiomyopathy and cardiac transplantation (age eight) preceded neuromuscular weakness by several years (age 12). The phenotype comprised distal weakness and severe sensorimotor neuropathy. Nerve biopsy was primarily axonal with secondary demyelinating/remyelinating changes without "giant axons." Muscle biopsy showed extensive neuropathic changes that made myopathic changes difficult to interpret. Similar to previous cases, a p.Pro209Leu mutation in exon 3 of BAG3 was found. This case underlines the importance of evaluating for MFMs in patients with combined neuromuscular weakness and cardiomyopathy. Copyright © 2015 Elsevier B.V. All rights reserved.

Does exercise stimulate protein breakdown in humans? Isotopic approaches to the problem

International Nuclear Information System (INIS)

Wolfe, R.R.

1987-01-01

Protein metabolism in exercise has been investigated for 100 yr, yet it is still unclear if exercise induces an increased rate of protein breakdown. We have recently addressed this general question in a series of experiments in human subjects using stable isotopic tracers. In this paper, the results of those studies are reviewed. We have found that in light exercise the de-carboxylation of leucine is increased. However, urea production is not increased correspondingly, nor is the rate of incorporation into urea of nitrogen from either leucine or lysine. Further complicating the picture is the fact that lysine de-carboxylation is not markedly elevated in exercise. From these studies, we must conclude that isotopic techniques which have achieved general acceptance in other circumstances cannot reliably be used to answer the question of whether exercise stimulates protein breakdown in humans. However, these methods do provide results which enable a better understanding of the metabolism of the individual amino acids in exercise

Characterisation of kiwifruit and asparagus enzyme extracts, and their activities toward meat proteins.

Science.gov (United States)

Ha, Minh; Bekhit, Alaa El-Din; Carne, Alan; Hopkins, David L

2013-01-15

Two plant enzyme extracts from kiwifruit and asparagus were evaluated for their ability to hydrolyse commercially available substrates and proteins present in both beef connective tissue and topside myofibrillar extracts. The results show significant differences in protease activity depending on the assay used. Protease assays with connective tissue and meat myofibrillar extracts provide a more realistic evaluation of the potential of the enzymes for application in meat tenderization. Overall, the kiwifruit protease extract was found to be more effective at hydrolysing myofibrillar and collagen proteins than the asparagus protease extract. The two protease extracts appeared to target meat myofibrillar and collagen proteins differently, suggesting the potential of a synergistic effect of these proteases in improving the tenderness of specific cuts of meat, based on their intrinsic protein composition. Copyright © 2012 Elsevier Ltd. All rights reserved.

Inhibition of interaction between epigallocatechin-3-gallate and myofibrillar protein by cyclodextrin derivatives improves gel quality under oxidative stress.

Science.gov (United States)

Zhang, Yumeng; Chen, Lin; Lv, Yuanqi; Wang, Shuangxi; Suo, Zhiyao; Cheng, Xingguang; Xu, Xinglian; Zhou, Guanghong; Li, Zhixi; Feng, Xianchao

2018-06-01

High levels of polyphenols can interact with myofibrillar proteins (MPs), causing damage to a MP emulsion gel. In this study, β-cyclodextrins were used to reduce covalent and non-covalent interaction between epigallocatechin-3-gallate (EGCG) and MPs under oxidative stress. The loss of both thiol and free amine groups and the unfolding of MPs caused by EGCG (80 μM/g protein) were significantly prevented by β-cyclodextrins, and the structural stability and solubility were improved. MP emulsion gel treated with EGCG (80 μM/g protein) had the highest cooking loss (68.64%) and gel strength (0.51 N). Addition of β-cyclodextrins significantly reduced cooking loss (26.24-58.20%) and improved gel strength (0.31-0.41 N) of MP emulsion gel jeopardized by EGCG under oxidative stress. Damage to the emulsifying properties of MPs caused by EGCG was significantly prevented by addition of β-cyclodextrins. β-cyclodextrins reduced interaction between EGCG and MPs in the order Methyl-β-cyclodextrin > (2-Hydroxypropyl)-β-cyclodextrin > β-cyclodextrin. In absence of EGCG, addition of β-cyclodextrins partly protected MPs from oxidative attack and improved its solubility. It is concluded that β-cyclodextrins does not markedly reduce the antioxidant ability of EGCG according to carbonyl analysis, and can effectively increase EGCG loading to potentially provide more durable antioxidant effect for meat products during processing, transportation and storage. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extração de proteínas miofibrilares de carne bovina para elaboração de filmes comestíveis Extraction of bovine meat myofibrillar proteins for elaboration edible films

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Sílvia M. A. de Souza

2004-12-01

Full Text Available A utilização de proteínas miofibrilares de carne na elaboração de filmes comestíveis implica, inicialmente, na obtenção desta macromolécula, uma vez que ela é indisponível comercialmente. Assim, os objetivos deste trabalho foram a obtenção e caracterização de proteínas miofibrilares de carne bovina, em escala de laboratório, e a elaboração e caracterização da microestrutura de filmes à base dessas proteínas. As proteínas miofibrilares foram extraídas do músculo Semitendinosus bovino, pós rigor mortis, empregando-se uma técnica de extração por centrifugação diferencial em solução tampão, com diferentes concentrações salinas, segundo metodologia de EISELE & BREKKE [13] modificada neste trabalho. As proteínas, assim obtidas, foram liofilizadas (PML e analisadas para determinação do teor de proteínas, de lipídios, de sais minerais, de cinzas e da umidade. A composição de aminoácidos foi determinada por cromatografia de troca iônica e o perfil eletroforético foi determinado em gel de poliacrilamida. Alguns filmes foram elaborados com 1g de PML/100g de solução, 60g de glicerol/100g de proteínas e ácido acético glacial para ajuste do pH=2,8. A microestrutura desses filmes foram analisadas por microscopia eletrônica de varredura. A PML, que apresentou teor de proteínas de 84,3%, foi composta de diversas frações de proteínas miofibrilares, com destaque para frações da miosina e da actina, segundo os resultados da eletroforese. Trabalhando-se a composição de aminoácidos, verificou-se que a maior contribuição energética das interações potenciais dos aminoácidos, foram as provenientes de ligações covalentes (58,3%, seguidas das interações iônicas (35,72%. A microestrutura do filme revelou uma estrutura pouco homogênea, porém coesa e densa e uma matriz protéica compacta e fina.The use of meat myofibrillar proteins for edible film production involves initially the extraction of the

The effect of eicosapentaenoic and docosahexaenoic acid on protein synthesis and breakdown in murine C2C12 myotubes

International Nuclear Information System (INIS)

Kamolrat, Torkamol; Gray, Stuart R.

2013-01-01

Highlights: ► EPA can enhance protein synthesis and retard protein breakdown in muscle cells. ► These effects were concurrent with increases in p70s6k and FOXO3a phosphorylation. ► EPA may be a useful tool in the treatment of muscle wasting conditions. -- Abstract: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been found to stimulate protein synthesis with little information regarding their effects on protein breakdown. Furthermore whether there are distinct effects of EPA and DHA remains to be established. The aim of the current study was to determine the distinct effects of EPA and DHA on protein synthesis, protein breakdown and signalling pathways in C2C12 myotubes. Fully differentiated C2C12 cells were incubated for 24 h with 0.1% ethanol (control), 50 μM EPA or 50 μM DHA prior to experimentation. After serum (4 h) and amino acid (1 h) starvation cells were stimulated with 2 mM L-leucine and protein synthesis measured using 3 H-labelled phenylalanine. Protein breakdown was measured using 3 H-labelled phenylalanine and signalling pathways (Akt, mTOR, p70S6k, 4EBP1, rps6 and FOXO3a) via Western blots. Data revealed that after incubation with EPA protein synthesis was 25% greater (P < 0.05) compared to control cells, with no effect of DHA. Protein breakdown was 22% (P < 0.05) lower, compared to control cells, after incubation with EPA, with no effect of DHA. Analysis of signalling pathways revealed that both EPA and DHA incubation increased (P < 0.05) p70s6k phosphorylation, EPA increased (P < 0.05) FOXO3a phosphorylation, with no alteration in other signalling proteins. The current study has demonstrated distinct effects of EPA and DHA on protein metabolism with EPA showing a greater ability to result in skeletal muscle protein accretion

The effect of eicosapentaenoic and docosahexaenoic acid on protein synthesis and breakdown in murine C2C12 myotubes

Energy Technology Data Exchange (ETDEWEB)

Kamolrat, Torkamol [Musculoskeletal Research Programme, Institute of Medical Sciences, University of Aberdeen, AB25 2ZD (United Kingdom); Gray, Stuart R., E-mail: s.r.gray@abdn.ac.uk [Musculoskeletal Research Programme, Institute of Medical Sciences, University of Aberdeen, AB25 2ZD (United Kingdom)

2013-03-22

Highlights: ► EPA can enhance protein synthesis and retard protein breakdown in muscle cells. ► These effects were concurrent with increases in p70s6k and FOXO3a phosphorylation. ► EPA may be a useful tool in the treatment of muscle wasting conditions. -- Abstract: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been found to stimulate protein synthesis with little information regarding their effects on protein breakdown. Furthermore whether there are distinct effects of EPA and DHA remains to be established. The aim of the current study was to determine the distinct effects of EPA and DHA on protein synthesis, protein breakdown and signalling pathways in C2C12 myotubes. Fully differentiated C2C12 cells were incubated for 24 h with 0.1% ethanol (control), 50 μM EPA or 50 μM DHA prior to experimentation. After serum (4 h) and amino acid (1 h) starvation cells were stimulated with 2 mM L-leucine and protein synthesis measured using {sup 3}H-labelled phenylalanine. Protein breakdown was measured using {sup 3}H-labelled phenylalanine and signalling pathways (Akt, mTOR, p70S6k, 4EBP1, rps6 and FOXO3a) via Western blots. Data revealed that after incubation with EPA protein synthesis was 25% greater (P < 0.05) compared to control cells, with no effect of DHA. Protein breakdown was 22% (P < 0.05) lower, compared to control cells, after incubation with EPA, with no effect of DHA. Analysis of signalling pathways revealed that both EPA and DHA incubation increased (P < 0.05) p70s6k phosphorylation, EPA increased (P < 0.05) FOXO3a phosphorylation, with no alteration in other signalling proteins. The current study has demonstrated distinct effects of EPA and DHA on protein metabolism with EPA showing a greater ability to result in skeletal muscle protein accretion.

Adverse effects of cyclosporine A on HSP25, alpha B-crystallin and myofibrillar cytoskeleton in rat heart

International Nuclear Information System (INIS)

Stacchiotti, Alessandra; Bonomini, Francesca; Lavazza, Antonio; Rodella, Luigi Fabrizio; Rezzani, Rita

2009-01-01

Cyclosporine (CsA) is a universally used immunosuppressive drug which induces adverse side effects in several organs, but its impact on the heart is still controversial. Small heat shock proteins (sHSPs), such as HSP25 and alpha B-crystallin, are cytoprotective stress proteins exceptionally represented in the heart. They act as myofibrillar chaperones that help actin and desmin to maintain their optimum configuration and stability, thereby antagonizing oxidative damage. The present study examined: (1) the cardiac distribution and abundance of HSP25 and alpha B-crystallin in rats receiving CsA at a therapeutic dosage (15 mg/kg/day) for 42 days and 63 days; (2) the presence of myofibrillar proteins, such as actin, alpha-actinin and desmin following the CsA treatments; (3) the subcellular effects of prolonged CsA exposure on the cardiomyocytes by histopathology and transmission electron microscopy. After 63 days CsA intake, sHSPs translocated from a regular sarcomeric pattern to peripheral sarcolemma and intercalated discs, together with actin and desmin. In contrast, the sarcomeric alpha-actinin pattern did not change in all experimental groups. The abundance of actin and HSP25 was unchanged in every time point of treatment while after 63 days CsA, alpha B-crystallin and desmin levels significantly decreased. Furthermore CsA induced fibrosis, irregular sarcomeric alignment and damaged desmosomes. These findings indicate that following prolonged CsA exposure, the cardiac muscle network was affected. In particular, the translocation of sHSPs to intercalated discs merits special consideration as a direct compensatory mechanism to limit CsA cardiotoxicity.

Quantity and functionality of protein fractions in chicken breast fillets affected by white striping.

Science.gov (United States)

Mudalal, S; Babini, E; Cavani, C; Petracci, M

2014-08-01

Recently, white striations parallel to muscle fibers direction have been observed on the surface of chicken breast, which could be ascribed to intensive growth selection. The aim of this study was to evaluate the effect of white striping on chemical composition with special emphasis on myofibrillar and sarcoplasmic protein fractions that are relevant to the processing features of chicken breast meat. During this study, a total of 12 pectoralis major muscles from both normal and white striped fillets were used to evaluate chemical composition, protein solubility (sarcoplasmic, myofibrillar, and total protein solubility), protein quantity (sarcoplasmic, myofibrillar, and stromal proteins), water holding capacity, and protein profile by SDS-PAGE analysis. White-striped fillets exhibited a higher percentage of moisture (75.4 vs. 73.8%; P cooking loss (33.7 vs. 27.4%; P chicken breast meat with white striping defect had different chemical composition (more fat and less protein) and protein quality and quantity (low content of myofibrillar proteins and high content of stromal proteins) with respect to normal meat. Furthermore, white striped fillets had lower protein functionality (higher cooking loss). All the former changes indicate that white striping has great impact on quality characteristics of chicken breast meat. © Poultry Science Association Inc.

Exercise & NSAID: Effect on muscle protein synthesis in knee osteoarthritis patients?

DEFF Research Database (Denmark)

Petersen, S.G.; Miller, Ben F; Hansen, M

2011-01-01

the contralateral leg remained rested. Twenty-four hours after exercise, we determined circulating concentrations of inflammatory parameters and measured FSR of myofibrillar and sarcoplasmic protein fractions of vastus lateralis muscle and patellar tendon collagen protein by the direct incorporation method using...... a flooding dose of 13C/12C-proline.RESULTS:Circulating levels of prostaglandin F2α were lower in the NSAID group compared with the placebo group (P effect of exercise on FSR in muscle myofibrillar (P = 0.003) and sarcoplasmic protein (P = 0.026) but not in tendon...... collagen protein (P = 0.52). No overall significant effect of the drug was seen on either of the tissue protein fractions (P > 0.05) or on the interaction between the drug and exercise on FSR in tendon collagen (P = 0.21), muscle myofibrillar (P = 0.68), or sarcoplasmic protein, FSR (P = 0.16).CONCLUSION...

Whole body and forearm substrate metabolism in hyperthyroidism: evidence of increased basal muscle protein breakdown.

Science.gov (United States)

Riis, Anne Lene Dalkjaer; Jørgensen, Jens Otto Lunde; Gjedde, Signe; Nørrelund, Helene; Jurik, Anne Grethe; Nair, K S; Ivarsen, Per; Weeke, Jørgen; Møller, Niels

2005-06-01

Thyroid hormones have significant metabolic effects, and muscle wasting and weakness are prominent clinical features of chronic hyperthyroidism. To assess the underlying mechanisms, we examined seven hyperthyroid women with Graves' disease before (Ht) and after (Eut) medical treatment and seven control subjects (Ctr). All subjects underwent a 3-h study in the postabsorptive state. After regional catheterization, protein dynamics of the whole body and of the forearm muscles were measured by amino acid tracer dilution technique using [15N]phenylalanine and [2H4]tyrosine. Before treatment, triiodothyronine was elevated (6.6 nmol/l) and whole body protein breakdown was increased 40%. The net forearm release of phenylalanine was increased in hyperthyroidism (microg.100 ml(-1).min(-1)): -7.0 +/- 1.2 Ht vs. -3.8 +/- 0.8 Eut (P = 0.04), -4.2 +/- 0.3 Ctr (P = 0.048). Muscle protein breakdown, assessed by phenylalanine rate of appearance, was increased (microg.100 ml(-1).min(-1)): 15.5 +/- 2.0 Ht vs. 9.6 +/- 1.4 Eut (P = 0.03), 9.9 +/- 0.6 Ctr (P = 0.02). Muscle protein synthesis rate did not differ significantly. Muscle mass and muscle function were decreased 10-20% before treatment. All abnormalities were normalized after therapy. In conclusion, our results show that hyperthyroidism is associated with increased muscle amino acid release resulting from increased muscle protein breakdown. These abnormalities can explain the clinical manifestations of sarcopenia and myopathy.

Fish oil supplementation suppresses resistance exercise and feeding-induced increases in anabolic signaling without affecting myofibrillar protein synthesis in young men.

Science.gov (United States)

McGlory, Chris; Wardle, Sophie L; Macnaughton, Lindsay S; Witard, Oliver C; Scott, Fraser; Dick, James; Bell, J Gordon; Phillips, Stuart M; Galloway, Stuart D R; Hamilton, D Lee; Tipton, Kevin D

2016-03-01

Fish oil (FO) supplementation potentiates muscle protein synthesis (MPS) in response to a hyperaminoacidemic-hyperinsulinemic infusion. Whether FO supplementation potentiates MPS in response to protein ingestion or when protein ingestion is combined with resistance exercise (RE) remains unknown. In a randomized, parallel group design, 20 healthy males were randomized to receive 5 g/day of either FO or coconut oil control (CO) for 8 weeks. After supplementation, participants performed a bout of unilateral RE followed by ingestion of 30 g of whey protein. Skeletal muscle biopsies were obtained before and after supplementation for assessment of muscle lipid composition and relevant protein kinase activities. Infusion of L-[ring-(13)C6] phenylalanine was used to measure basal myofibrillar MP Sat rest (REST), in a nonexercised leg following protein ingestion (FED) and following RE and protein ingestion (FEDEX).MPS was significantly elevated above REST during FEDEX in both the FO and CO groups, but there was no effect of supplementation. There was a significant increase in MPS in both groups above REST during FED but no effect of supplementation. Supplementation significantly decreased pan PKB activity at RESTin the FO group but not the CO group. There was a significant increase from REST at post-RE for PKB and AMPKα2 activity in the CO group but not in the FO group. In FEDEX, there was a significant increase in p70S6K1 activity from REST at 3 h in the CO group only. These data highlight that 8 weeks of FO supplementation alters kinase signaling activity in response to RE plus protein ingestion without influencing MPS. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Nuclear envelope breakdown induced by herpes simplex virus type 1 involves the activity of viral fusion proteins

Energy Technology Data Exchange (ETDEWEB)

Maric, Martina; Haugo, Alison C. [Department of Microbiology, University of Iowa, Iowa City, IA 52242 (United States); Dauer, William [Department of Neurology, University of Michigan, Ann Arbor, MI 48109 (United States); Johnson, David [Department of Microbiology and Immunology, Oregon Health Sciences University, Portland, OR 97201 (United States); Roller, Richard J., E-mail: richard-roller@uiowa.edu [Department of Microbiology, University of Iowa, Iowa City, IA 52242 (United States)

2014-07-15

Herpesvirus infection reorganizes components of the nuclear lamina usually without loss of integrity of the nuclear membranes. We report that wild-type HSV infection can cause dissolution of the nuclear envelope in transformed mouse embryonic fibroblasts that do not express torsinA. Nuclear envelope breakdown is accompanied by an eight-fold inhibition of virus replication. Breakdown of the membrane is much more limited during infection with viruses that lack the gB and gH genes, suggesting that breakdown involves factors that promote fusion at the nuclear membrane. Nuclear envelope breakdown is also inhibited during infection with virus that does not express UL34, but is enhanced when the US3 gene is deleted, suggesting that envelope breakdown may be enhanced by nuclear lamina disruption. Nuclear envelope breakdown cannot compensate for deletion of the UL34 gene suggesting that mixing of nuclear and cytoplasmic contents is insufficient to bypass loss of the normal nuclear egress pathway. - Highlights: • We show that wild-type HSV can induce breakdown of the nuclear envelope in a specific cell system. • The viral fusion proteins gB and gH are required for induction of nuclear envelope breakdown. • Nuclear envelope breakdown cannot compensate for deletion of the HSV UL34 gene.

Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training.

Directory of Open Access Journals (Sweden)

Evelyn B Parr

Full Text Available INTRODUCTION: The culture in many team sports involves consumption of large amounts of alcohol after training/competition. The effect of such a practice on recovery processes underlying protein turnover in human skeletal muscle are unknown. We determined the effect of alcohol intake on rates of myofibrillar protein synthesis (MPS following strenuous exercise with carbohydrate (CHO or protein ingestion. METHODS: In a randomized cross-over design, 8 physically active males completed three experimental trials comprising resistance exercise (8×5 reps leg extension, 80% 1 repetition maximum followed by continuous (30 min, 63% peak power output (PPO and high intensity interval (10×30 s, 110% PPO cycling. Immediately, and 4 h post-exercise, subjects consumed either 500 mL of whey protein (25 g; PRO, alcohol (1.5 g·kg body mass⁻¹, 12±2 standard drinks co-ingested with protein (ALC-PRO, or an energy-matched quantity of carbohydrate also with alcohol (25 g maltodextrin; ALC-CHO. Subjects also consumed a CHO meal (1.5 g CHO·kg body mass⁻¹ 2 h post-exercise. Muscle biopsies were taken at rest, 2 and 8 h post-exercise. RESULTS: Blood alcohol concentration was elevated above baseline with ALC-CHO and ALC-PRO throughout recovery (P<0.05. Phosphorylation of mTOR(Ser2448 2 h after exercise was higher with PRO compared to ALC-PRO and ALC-CHO (P<0.05, while p70S6K phosphorylation was higher 2 h post-exercise with ALC-PRO and PRO compared to ALC-CHO (P<0.05. Rates of MPS increased above rest for all conditions (∼29-109%, P<0.05. However, compared to PRO, there was a hierarchical reduction in MPS with ALC-PRO (24%, P<0.05 and with ALC-CHO (37%, P<0.05. CONCLUSION: We provide novel data demonstrating that alcohol consumption reduces rates of MPS following a bout of concurrent exercise, even when co-ingested with protein. We conclude that alcohol ingestion suppresses the anabolic response in skeletal muscle and may therefore impair recovery and adaptation

Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage.

Science.gov (United States)

Damas, Felipe; Phillips, Stuart M; Libardi, Cleiton A; Vechin, Felipe C; Lixandrão, Manoel E; Jannig, Paulo R; Costa, Luiz A R; Bacurau, Aline V; Snijders, Tim; Parise, Gianni; Tricoli, Valmor; Roschel, Hamilton; Ugrinowitsch, Carlos

2016-09-15

Skeletal muscle hypertrophy is one of the main outcomes from resistance training (RT), but how it is modulated throughout training is still unknown. We show that changes in myofibrillar protein synthesis (MyoPS) after an initial resistance exercise (RE) bout in the first week of RT (T1) were greater than those seen post-RE at the third (T2) and tenth week (T3) of RT, with values being similar at T2 and T3. Muscle damage (Z-band streaming) was the highest during post-RE recovery at T1, lower at T2 and minimal at T3. When muscle damage was the highest, so was the integrated MyoPS (at T1), but neither were related to hypertrophy; however, integrated MyoPS at T2 and T3 were correlated with hypertrophy. We conclude that muscle hypertrophy is the result of accumulated intermittent increases in MyoPS mainly after a progressive attenuation of muscle damage. Skeletal muscle hypertrophy is one of the main outcomes of resistance training (RT), but how hypertrophy is modulated and the mechanisms regulating it are still unknown. To investigate how muscle hypertrophy is modulated through RT, we measured day-to-day integrated myofibrillar protein synthesis (MyoPS) using deuterium oxide and assessed muscle damage at the beginning (T1), at 3 weeks (T2) and at 10 weeks of RT (T3). Ten young men (27 (1) years, mean (SEM)) had muscle biopsies (vastus lateralis) taken to measure integrated MyoPS and muscle damage (Z-band streaming and indirect parameters) before, and 24 h and 48 h post resistance exercise (post-RE) at T1, T2 and T3. Fibre cross-sectional area (fCSA) was evaluated using biopsies at T1, T2 and T3. Increases in fCSA were observed only at T3 (P = 0.017). Changes in MyoPS post-RE at T1, T2 and T3 were greater at T1 (P Muscle damage was the highest during post-RE recovery at T1, attenuated at T2 and further attenuated at T3. The change in MyoPS post-RE at both T2 and T3, but not at T1, was strongly correlated (r ≈ 0.9, P muscle hypertrophy. Initial Myo

Effects of prerigor pressurization on the emulsifying capacity of muscle protein

Energy Technology Data Exchange (ETDEWEB)

Elgasim, E.A.; Kennick, W.H.; Anglemier, A.F.; Elkhalifa, E.A.; Koohmaraie, M.

1982-05-01

The emulsifying capacities of pressure treated and control muscle homogenates, sarcoplasmic protein and myofibrillar proteins of ovine and bovine longissimus muscles were determined at 2, 6, 24 and 168 hr postmortem. The pH of the intact muscle, muscle homogenate and myofibrillar protein extract were taken at these times. Before onset of rigor mortis, the emulsifying capacity of muscle homogenate from the control samples was higher than the pressure treated samples. At 24 and 168 hr postmortem, the pressure treated and control samples were not significantly different (P>0.05) for emulsifying capacity. At 2 hr postmortem, the emulsifying capacity of myofibrillar protein extract from control samples was higher (P<0.05) than that from pressure treated samples; thereafter, the emulsification curve for the pressure treated samples was higher than that of the control. The emulsification capacity of sarcoplasmic proteins from control muscles was slightly, but consistently, higher than that from pressure treated muscles throughout the test period. Overall, the emulsification capacity of muscle proteins was not detrimentally affected by pressure treatment.

Coordinated collagen and muscle protein synthesis in human patella tendon and quadriceps muscle after exercise

DEFF Research Database (Denmark)

Miller, Benjamin F; Olesen, Jens L; Hansen, Mette

2005-01-01

We hypothesized that an acute bout of strenuous, non-damaging exercise would increase rates of protein synthesis of collagen in tendon and skeletal muscle but these would be less than those of muscle myofibrillar and sarcoplasmic proteins. Two groups (n = 8 and 6) of healthy young men were studied...... collagen (0.077% h(-1)), muscle collagen (0.054% h(-1)), myofibrillar protein (0.121% h(-1)), and sarcoplasmic protein (0.134% h(-1))). The rates decreased toward basal values by 72 h although rates of tendon collagen and myofibrillar protein synthesis remained elevated. There was no tissue damage...... of muscle visible on histological evaluation. Neither tissue microdialysate nor serum concentrations of IGF-I and IGF binding proteins (IGFBP-3 and IGFBP-4) or procollagen type I N-terminal propeptide changed from resting values. Thus, there is a rapid increase in collagen synthesis after strenuous exercise...

Effect of physiologic hyperinsulinemia on skeletal muscle protein synthesis and breakdown in man

International Nuclear Information System (INIS)

Gelfand, R.A.; Barrett, E.J.

1987-01-01

Although insulin stimulates protein synthesis and inhibits protein breakdown in skeletal muscle in vitro, the actual contribution of these actions to its anabolic effects in man remains unknown. Using the forearm perfusion method together with systemic infusion of L-[ring-2,6-3H]phenylalanine and L-[1- 14 C]leucine, we measured steady state amino acid exchange kinetics across muscle in seven normal males before and in response to a 2-h intraarterial infusion of insulin. Postabsorptively, the muscle disposal (Rd) of phenylalanine (43 +/- 5 nmol/min per 100 ml forearm) and leucine (113 +/- 13) was exceeded by the concomitant muscle production (Ra) of these amino acids (57 +/- 5 and 126 +/- 9 nmol/min per dl, respectively), resulting in their net release from the forearm (-14 +/- 4 and -13 +/- 5 nmol/min per dl, respectively). In response to forearm hyperinsulinemia (124 +/- 11 microU/ml), the net balance of phenylalanine and leucine became positive (9 +/- 3 and 61 +/- 8 nmol/min per dl, respectively (P less than 0.005 vs. basal). Despite the marked increase in net balance, the tissue Rd for both phenylalanine (42 +/- 2) and leucine (124 +/- 9) was unchanged from baseline, while Ra was markedly suppressed (to 33 +/- 5 and 63 +/- 9 nmol/min per dl, respectively, P less than 0.01). Since phenylalanine is not metabolized in muscle (i.e., its only fates are incorporation into or release from protein) these results strongly suggest that in normal man, physiologic elevations in insulin promote net muscle protein anabolism primarily by inhibiting protein breakdown, rather than by stimulating protein synthesis

Analysis of myofibrillar proteins and transcripts in adult skeletal muscles of the American lobster Homarus americanus: variable expression of myosins, actin and troponins in fast, slow-twitch and slow-tonic fibres.

Science.gov (United States)

Medler, Scott; Mykles, Donald L

2003-10-01

Skeletal muscles are diverse in their contractile properties, with many of these differences being directly related to the assemblages of myofibrillar isoforms characteristic of different fibers. Crustacean muscles are similar to other muscles in this respect, although the majority of information about differences in muscle organization comes from vertebrate species. In the present study, we examined the correlation between myofibrillar protein isoforms and the patterns of myofibrillar gene expression in fast, slow-phasic (S(1)) and slow-tonic (S(2)) fibers of the American lobster Homarus americanus. SDS-PAGE and western blotting were used to identify isoform assemblages of myosin heavy chain (MHC), P75, troponin T (TnT) and troponin I (TnI). RT-PCR was used to monitor expression of fast and slow (S(1)) MHC, P75 and actin in different fiber types, and the MHC and actin levels were quantified by real-time PCR. Fast and slow fibers from the claw closers predominantly expressed fast and S(1) MHC, respectively, but also lower levels of the alternate MHC. By contrast, fast fibers from the deep abdominal muscle expressed fast MHC exclusively. In addition, slow muscles expressed significantly higher levels of actin than fast fibers. A distal bundle of fibers in the cutter claw closer muscle was found to be composed of a mixture of S(1) and S(2) fibers, many of which possessed a mixture of S(1) and S(2) MHC isoforms. This pattern supports the idea that S(1) and S(2) fibers represent extremes in a continuum of slow muscle phenotype. Overall, these patterns demonstrate that crustacean skeletal muscles cannot be strictly categorized into discrete fiber types, but a muscle's properties probably represent a point on a continuum of fiber types. This trend may result from differences in innervation pattern, as each muscle is controlled by a unique combination of phasic, tonic or both phasic and tonic motor nerves. In this respect, future studies examining how muscle phenotype

Proteomic evaluation of myofibrillar carbonylation in chilled fish mince and its inhibition by catechin.

Science.gov (United States)

Pazos, Manuel; Maestre, Rodrigo; Gallardo, José M; Medina, Isabel

2013-01-01

The present study investigates the susceptibility of individual myofibrillar proteins from mackerel (Scomber scombrus) mince to undergo carbonylation reactions during chilled storage, and the antioxidant capacity of (+)-catechin to prevent oxidative processes of proteins. The carbonylation of each particular protein was quantified by combining the labelling of protein carbonyls by fluorescein-5-thiosemicarbazide (FTSC) with 1-D or 2-D gel electrophoresis. Alpha skeletal actin, glycogen phosphorylase, unnamed protein product (UNP) similar to enolase, pyruvate kinase, isoforms of creatine kinase, aldolase A and an isoform of glyceraldehyde 3-phosphate dehydrogenase (G3PDH) showed elevated oxidation in chilled non-supplemented mince. Myosin heavy chain (MHC) was not carbonylated in chilled muscle, but an extensive MHC degradation was observed in those samples. The supplementation of catechin reduced protein oxidation and lipid oxidation in a concentration-dependent manner: control>25>100≈200ppm. Therefore, the highest catechin concentrations (100 and 200ppm) exhibited the strongest antioxidant activity. Catechin (200ppm) reduced significantly carbonylation of protein spots identified as glycogen phosphorylase, pyruvate kinase muscle isozyme, isoforms of creatine kinase. Conversely, catechin was ineffective to inhibit the oxidation of actin and UNP similar to enolase. These results draw attention to the inefficiency of catechin to prevent actin oxidation, in contrast to the extremely high efficiency of catechin in inhibiting oxidation of lipids and other proteins. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of starvation on protein synthesis and nucleic acid metabolism in the muscle of the barred sand bass Paralabrax nebulifer

Energy Technology Data Exchange (ETDEWEB)

Lowery, M.S.

1987-01-01

Starvation induced different protein synthesis responses in red and white muscle of the barred sand bass Paralabrax nebulifer. Red muscle had /sup 14/C-leucine incorporation rates into total protein which were several times higher than white muscle in both the fed and starved states. Muscle was separated into a myofibrillar fraction consisting of the structural proteins and a sarcoplasmic fraction consisting of soluble proteins. Synthesis of the myofibrillar fraction of white muscle decreased by 90%, while red muscle myofibrillar synthesis remained essentially unchanged. Changes in the labeling of several enzymes purified from the sarcoplasmic fraction were different even though the overall loss of enzyme activity was similar, suggesting that changes in synthesis rates were important in maintaining appropriate relative enzyme concentrations.

Laser-Induced Breakdown Spectroscopy Based Protein Assay for Cereal Samples.

Science.gov (United States)

Sezer, Banu; Bilge, Gonca; Boyaci, Ismail Hakki

2016-12-14

Protein content is an important quality parameter in terms of price, nutritional value, and labeling of various cereal samples. However, conventional analysis methods, namely, Kjeldahl and Dumas, have major drawbacks such as long analysis time, titration mistakes, and carrier gas dependence with high purity. For this reason, there is an urgent need for rapid, reliable, and environmentally friendly technologies for protein analysis. The present study aims to develop a new method for protein analysis in wheat flour and whole meal by using laser-induced breakdown spectroscopy (LIBS), which is a multielemental, fast, and simple spectroscopic method. Unlike the Kjeldahl and Dumas methods, it has potential to analyze a high number of samples in considerably short time. In the study, nitrogen peaks in LIBS spectra of wheat flour and whole meal samples with different protein contents were correlated with results of the standard Dumas method with the aid of chemometric methods. A calibration graph showed good linearity with the protein content between 7.9 and 20.9% and a 0.992 coefficient of determination (R 2 ). The limit of detection was calculated as 0.26%. The results indicated that LIBS is a promising and reliable method with its high sensitivity for routine protein analysis in wheat flour and whole meal samples.

Incorporation of DL(1-14C)-leucine into muscle proteins in buffalo calves and its response to exogenous insulin

International Nuclear Information System (INIS)

Vivekanandan, R.; Singh, L.N.

1976-01-01

Protein synthesis and the effect of insulin on this process have been studied in buffalo skeletal muscles using DL(1- 14 C)-leucine. The muscle fibres isolated from triceps, showed highest specific radioactivity (SRA) in the sarcoplasmic proteins followed by myofibrillar and stroma proteins. Exogenous insulin stimulated the incorporation in the myofibrillar and stroma fractions but not in the sarcoplasmic proteins. Radioscanning of the polyacrylamide gel electrophorograms further revealed preferential labelling of only some of the myofibrillar proteins in the presence of exogenous insulin. Statistically significant differences in the SRA were observed between nuclear, mitochondrial and post-mitochondrial proteins without exogenous insulin the post-mitochondrial proteins showing highest SRA. Addition of insulin to the assay medium significantly stimulated the incorporation in the nuclear fraction whereas mitochondrial and post-mitochondrial fractions did not respond. Intramuscular injection of insulin, 3 hours prior to collection of tissue, stimulated the incorporation in nuclear as well as post-mitochondrial fractions but had no effect on the mitochondrial protein synthesis. (author)

Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients

DEFF Research Database (Denmark)

Jespersen, Jakob G; Nedergaard, Anders; Reitelseder, Søren

2011-01-01

Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR), glycogen synthase kinase 3β (GSK3β) and forkhead box O (FoxO) pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors invol...... involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU) patients compared with healthy controls....

Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients

DEFF Research Database (Denmark)

Jespersen, Jakob G; Nedergaard, Anders; Reitelseder, Søren

2011-01-01

Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR), glycogen synthase kinase 3ß (GSK3ß) and forkhead box O (FoxO) pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors invol...... involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU) patients compared with healthy controls....

Konjac flour improved textural and water retention properties of transglutaminase-mediated, heat-induced porcine myofibrillar protein gel: Effect of salt level and transglutaminase incubation.

Science.gov (United States)

Chin, Koo B; Go, Mi Y; Xiong, Youling L

2009-03-01

Functional properties of heat-induced gels prepared from microbial transglutaminase (TG)-treated porcine myofibrillar protein (MP) containing sodium caseinate with or without konjac flour (KF) under various salt concentrations (0.1, 0.3 and 0.6MNaCl) were evaluated. The mixed MP gels with KF exhibited improved cooking yields at all salt concentrations. TG treatment greatly enhanced gel strength and elasticity (storage modulus, G') at 0.6M NaCl, but not at lower salt concentrations. The combination of KF and TG improved the gel strength at 0.1 and 0.3M NaCl and G' at all salt concentrations, when compared with non-TG controls. Incubation of MP suspensions (sols) with TG promoted the disappearance of myosin heavy chain and the production of polymers. The TG-treated MP mixed gels had a compact structure, compared to those without TG, and the KF incorporation modified the gel matrix and increased its water-holding capacity. Results from differential scanning calorimetry suggested possible interactions of MP with KF, which may explain the changes in the microstructure of the heat-induced gels.

Exome sequencing identifies variants in two genes encoding the LIM-proteins NRAP and FHL1 in an Italian patient with BAG3 myofibrillar myopathy.

Science.gov (United States)

D'Avila, Francesca; Meregalli, Mirella; Lupoli, Sara; Barcella, Matteo; Orro, Alessandro; De Santis, Francesca; Sitzia, Clementina; Farini, Andrea; D'Ursi, Pasqualina; Erratico, Silvia; Cristofani, Riccardo; Milanesi, Luciano; Braga, Daniele; Cusi, Daniele; Poletti, Angelo; Barlassina, Cristina; Torrente, Yvan

2016-06-01

Myofibrillar myopathies (MFMs) are genetically heterogeneous dystrophies characterized by the disintegration of Z-disks and myofibrils and are associated with mutations in genes encoding Z-disk or Z-disk-related proteins. The c.626 C > T (p.P209L) mutation in the BAG3 gene has been described as causative of a subtype of MFM. We report a sporadic case of a 26-year-old Italian woman, affected by MFM with axonal neuropathy, cardiomyopathy, rigid spine, who carries the c.626 C > T mutation in the BAG3 gene. The patient and her non-consanguineous healthy parents and brother were studied with whole exome sequencing (WES) to further investigate the genetic basis of this complex phenotype. In the patient, we found that the BAG3 mutation is associated with variants in the NRAP and FHL1 genes that encode muscle-specific, LIM domain containing proteins. Quantitative real time PCR, immunohistochemistry and Western blot analysis of the patient's muscular biopsy showed the absence of NRAP expression and FHL1 accumulation in aggregates in the affected skeletal muscle tissue. Molecular dynamic analysis of the mutated FHL1 domain showed a modification in its surface charge, which could affect its capability to bind its target proteins. To our knowledge this is the first study reporting, in a BAG3 MFM, the simultaneous presence of genetic variants in the BAG3 and FHL1 genes (previously described as independently associated with MFMs) and linking the NRAP gene to MFM for the first time.

Whey and casein labelled with L-[1-13C]-leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion

DEFF Research Database (Denmark)

Reitelseder, Søren; Agergaard, Jakob; Doessing, Simon

2011-01-01

to a single bolus intake of whey or casein after performance of heavy resistance exercise. Young male individuals were randomly assigned to participate in two protein trials (n = 9) or one control trial (n = 8). Infusion of l-[1-(13)C]leucine was carried out, and either whey, casein (0.3 g/kg lean body mass......), or a noncaloric control drink was ingested immediately after exercise. l-[1-(13)C]leucine-labeled whey and casein were used while muscle protein synthesis (MPS) was assessed. Blood and muscle tissue samples were collected to measure systemic hormone and amino acid concentrations, tracer enrichments......, and myofibrillar protein synthesis. Western blots were used to investigate the Akt signaling pathway. Plasma insulin and branched-chain amino acid concentrations increased to a greater extent after ingestion of whey compared with casein. Myofibrillar protein synthesis was equally increased 1-6 h postexercise after...

Suspected myofibrillar myopathy in Arabian horses with a history of exertional rhabdomyolysis.

Science.gov (United States)

Valberg, S J; McKenzie, E C; Eyrich, L V; Shivers, J; Barnes, N E; Finno, C J

2016-09-01

Although exertional rhabdomyolysis (ER) is common in Arabian horses, there are no dedicated studies describing histopathological characteristics of muscle from Arabian horses with ER. To prospectively identify distinctive histopathological features of muscle from Arabian endurance horses with a history of ER (pro-ER) and to retrospectively determine their prevalence in archived samples from Arabian horses with exertional myopathies (retro-ER). Prospective and retrospective histopathological description. Middle gluteal muscle biopsies obtained from Arabian controls (n = 14), pro-ER (n = 13) as well as archived retro-ER (n = 25) muscle samples previously classified with type 2 polysaccharide storage myopathy (15/25), recurrent exertional rhabdomyolysis (7/25) and no pathology (3/25) were scored for histopathology and immunohistochemical staining of cytoskeletal proteins. Glutaraldehyde-fixed samples (2 pro-ER, one control) were processed for electron microscopy. Pro-ER and retro-ER groups were compared with controls using Mann-Whitney U and Fisher's exact tests. Centrally located myonuclei in mature myofibres were found in significantly more (Prhabdomyolysis, ectopic accumulation of cytoskeletal proteins and Z-disc degeneration bear a strong resemblance to a myofibrillar myopathy. While many of these horses were previously diagnosed with type 2 polysaccharide storage myopathy, pools of glycogen forming within disrupted myofibrils appeared to give the false appearance of a glycogen storage disorder. © 2015 EVJ Ltd.

Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients.

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Jakob G Jespersen

Full Text Available BACKGROUND: Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR, glycogen synthase kinase 3β (GSK3β and forkhead box O (FoxO pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU patients compared with healthy controls. METHODOLOGY/PRINCIPAL FINDINGS: ICU patients were systemically inflamed, moderately hyperglycemic, received insulin therapy, and showed a tendency to lower plasma branched chain amino acids compared with controls. Using Western blotting we measured Akt, GSK3β, mTOR, ribosomal protein S6 kinase (S6k, eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1, and muscle ring finger protein 1 (MuRF1; and by RT-PCR we determined mRNA expression of, among others, insulin-like growth factor 1 (IGF-1, FoxO 1, 3 and 4, atrogin1, MuRF1, interleukin-6 (IL-6, tumor necrosis factor α (TNF-α and myostatin. Unexpectedly, in critically ill ICU patients Akt-mTOR-S6k signaling was substantially higher compared with controls. FoxO1 mRNA was higher in patients, whereas FoxO3, atrogin1 and myostatin mRNAs and MuRF1 protein were lower compared with controls. A moderate correlation (r2=0.36, p<0.05 between insulin infusion dose and phosphorylated Akt was demonstrated. CONCLUSIONS/SIGNIFICANCE: We present for the first time muscle protein turnover signaling in critically ill ICU patients, and we show signaling pathway activity towards a stimulation of muscle protein synthesis and a somewhat inhibited proteolysis.

Myofibrillar myopathies: State of the art, present and future challenges.

Science.gov (United States)

Béhin, A; Salort-Campana, E; Wahbi, K; Richard, P; Carlier, R-Y; Carlier, P; Laforêt, P; Stojkovic, T; Maisonobe, T; Verschueren, A; Franques, J; Attarian, S; Maues de Paula, A; Figarella-Branger, D; Bécane, H-M; Nelson, I; Duboc, D; Bonne, G; Vicart, P; Udd, B; Romero, N; Pouget, J; Eymard, B

2015-10-01

Myofibrillar myopathies (MFM) have been described in the mid-1990s as a group of diseases sharing common histological features, including an abnormal accumulation of intrasarcoplasmic proteins, the presence of vacuoles and a disorganization of the intermyofibrillar network beginning at the Z-disk. The boundaries of this concept are still uncertain, and whereas six genes (DES, CRYAB, LDB3/ZASP, MYOT, FLNC and BAG3) are now classically considered as responsible for MFM, other entities such as FHL1 myopathy or Hereditary Myopathy with Early Respiratory Failure linked to mutations of titin can now as well be included in this group. The diagnosis of MFM is not always easy; as histological lesions can be focal, and muscle biopsy may be disappointing; this has led to a growing importance of muscle imaging, and the selectivity of muscle involvement has now been described in several disorders. Due to the rarity of these myopathies, if some clinical patterns (such as distal myopathy associated with cardiomyopathy due to desmin mutations) are now well known, surprises remain possible and should lead to systematic testing of the known genes in case of a typical histological presentation. In this paper, we aim at reviewing the data acquired on the six main genes listed above as well as presenting the experience from two French reference centres, Paris and Marseilles. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Effect of biostimulator on the incorporation of DL(1-14C)leucine into skeletal muscle proteins of buffalo

International Nuclear Information System (INIS)

Nath, N.C.; Singh, L.N.

1982-01-01

Incorporation of 14 C-leucine into muscle proteins of buffalo calves was studied in vitro using muscle fibre preparations from biceps femoris. Biostimulator (a spleen tissue extract) stimulated the incorporation of 14 C-leucine into total proteins to some extent, but inhibited the synthesis of sarcoplasmic proteins. There was no significant difference in the relative proportion of the individual sarcoplasmic and myofibrillar proteins in the presence or absence of biostimulator. In one major sarcoplasmic protein there was higher specific activity in the presence of biostimulator. In all the remaining 4 proteins the incorporation was inhibited. Among the myofibrillar proteins, the incorporation into troponins, myosin light chains and tropomyosin was stimulated in the presence of biostimulator. Myosin heavy chain and acting did not show any change in incorporation of 14 C-leucine after addition of the biostimulator. (author)

Gross and true ileal digestible amino acid contents of several animal body proteins and their hydrolysates.

Science.gov (United States)

Cui, J; Chong, B; Rutherfurd, S M; Wilkinson, B; Singh, H; Moughan, P J

2013-07-01

Amino acid compositions of ovine muscle, ovine myofibrillar protein, ovine spleen, ovine liver, bovine blood plasma, bovine blood globulins and bovine serum albumin and the amino acid compositions and in vivo (laboratory rat) true ileal amino acid digestibilities of hydrolysates (sequential hydrolysis with Neutrase, Alcalase and Flavourzyme) of these protein sources were determined. True ileal amino acid digestibility differed (Pprotein hydrolysates. The ovine myofibrillar protein and liver hydrolysates were the most digestible, with a mean true ileal digestibility across all amino acids of 99%. The least digestible protein hydrolysate was bovine serum albumin with a comparable mean true ileal digestibility of 93%. When the digestible amino acid contents were expressed as proportions relative to lysine, considerable differences, across the diverse protein sources, were found in the pattern of predicted absorbed amino acids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nutritional value and digestion rate of rhea meat proteins in association with storage and cooking processes.

Science.gov (United States)

Filgueras, Renata S; Gatellier, Philippe; Ferreira, Claude; Zambiazi, Rui C; Santé-Lhoutellier, Véronique

2011-09-01

The nutritional value of proteins was investigated after the storage and cooking of rhea M. Gastrocnemius pars interna. Oxidation of basic and aromatic amino acids, surface hydrophobicity and aggregation state of proteins, were determined in raw and cooked meat. In addition, myofibrillar proteins were exposed in vitro to proteases of the digestive tract. Cooking markedly affected the protein surface hydrophobicity. The BBP bound content was three times greater in cooked than in fresh rhea meat. A small increment in tryptophan content after cooking was observed. Storage influenced Schiff bases formation indicating the presence of protein-aldehyde adducts after cooking. High content of Schiff bases was found after cooking of samples stored for 5 days, demonstrating a probable implication of free amino groups, most likely from lysine. Cooking decreased the myofibrillar protein susceptibility to pepsin activity. After cooking, the proteolysis rate by pancreatic enzymes increased. Our findings support the importance of protein aggregation in the nutritional value of meat proteins. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparison of protein degradation, protein oxidation, and μ-calpain activation between pale, soft, and exudative and red, firm, and nonexudative pork during postmortem aging.

Science.gov (United States)

Yin, Y; Zhang, W G; Zhou, G H; Guo, B

2014-08-01

The objective of this study was to investigate the differences in protein modifications between pale, soft, and exudative (PSE) and red, firm, and nonexudative (RFN) pork during postmortem (PM) aging. Longissimus dorsi (LD) including 8 PSE and 8 RFN muscles were individually removed from 16 carcasses. These 16 LD muscles were vacuum packaged at 24 h after slaughter and stored at 4°C for 1, 3, and 5 d. The centrifugation loss, drip loss, color, protein solubility, protein oxidation, protein degradation including desmin, troponin T, and integrin, and μ-calpain activation were determined. The pH of PSE samples was significantly lower than that of RFN samples at both 1 and 24 h PM (P 0.05). In addition, PSE pork presented a lower solubility of sarcoplasmic protein, myofibrillar protein, and total protein than RFN pork except the solubility of myofibrillar protein at d 1 (P firm, and nonexudative pork presented lower intensity of intact 80 kDa calpain and greater intensity of autolyzed 76 kDa product compared to PSE pork (P < 0.01). The results indicate that the degree of μ-calpain activation, the extent of protein degradation including desmin and integrin, and the level of protein solubility in PSE pork could contribute to its low water holding capacity during PM storage.

No effect of anti-inflammatory medication on postprandial and postexercise muscle protein synthesis in elderly men with slightly elevated systemic inflammation

DEFF Research Database (Denmark)

Dideriksen, Kasper Juel; Reitelseder, Søren; Malmgaard-Clausen, Nikolai Mølkjær

2016-01-01

BACKGROUND: Based on circulating C-reactive protein (CRP) levels, some individuals develop slightly increased inflammation as they age. In elderly inflamed rats, the muscle response to protein feeding is impaired, whereas it can be maintained by treatment with non-steroidal anti-inflammatory drugs...... (NSAIDs). It is unknown whether this applies to elderly humans with increased inflammation. Thus, the muscle response to whey protein bolus ingestion with and without acute resistance exercise was compared between healthy elderly individuals and elderly individuals with slightly increased inflammation......protein synthetic response was measured as the fractional synthetic rate (FSR) and p70S6K phosphorylation-to-total protein ratio. RESULTS: The basal myofibrillar FSR and the myofibrillar FSR responses to whey protein bolus ingestion with and without acute resistance exercise were...

High pressure processing of meat: effects on ultrastructure and protein digestibility.

Science.gov (United States)

Kaur, Lovedeep; Astruc, Thierry; Vénien, Annie; Loison, Olivier; Cui, Jian; Irastorza, Marion; Boland, Mike

2016-05-18

The effects of high pressure processing (HPP, at 175 and 600 MPa) on the ultrastructure and in vitro protein digestion of bovine longissimus dorsi muscle meat were studied. HPP caused a significant change in the visual appearance and texture of the meat subjected to HPP at 600 MPa so that it appeared similar to cooked meat, unlike the meat subjected to HPP at 175 MPa that showed no significant visible change in the colour and texture compared to the raw meat. The muscles were subjected to digestion under simulated gastric conditions for 1 h and then under simulated small-intestinal conditions for a further 2 h. The digests were analysed using gel electrophoresis (SDS-PAGE) and ninhydrin assay for amino N. The effect of the acid conditions of the stomach alone was also investigated. Reduced SDS-PAGE results showed that pepsin-digested (60 min) HPP meats showed fewer proteins or peptides of high molecular weight than the pepsin-digested untreated meat, suggesting more breakdown of the parent proteins in HPP-treated meats. This effect was more pronounced in the muscles treated at 600 MPa. These results are in accordance with microscopy results, which showed greater changes in the myofibrillar structure after simulated gastric digestion of the sample processed at 600 MPa than at 175 MPa. Transmission electron microscopy also showed the presence of protein aggregates in the former sample, resulting probably from protein denaturation of sarcoplasmic proteins, in the subcellular space and between myofibrils; along with cell contraction (similar to that caused by heating) in the former.

Emulsifying and gelling properties of weakfish myofibrillar proteins as affected by squid mantle myofibrillar proteins in a model system

Directory of Open Access Journals (Sweden)

Daniela Mariel Suarez

2014-03-01

Full Text Available The aim of the present work was to investigate the physicochemical, biochemical and functional characteristics of both the myofibrils (MF and actomyosin (AM of squid mantle (Illex argentinus and weakfish (Cynoscion guatucupa muscles, and evaluate the influence of the addition of myofibrilar proteins from the squid mantle on the physicochemical and functional properties of those of the weakfish. After extraction, purification and characterization of the MF and AM of both species, emulsions of each protein fraction from each muscle were formulated. Mixtures of the MF or AM of both species were also analyzed. The emulsifying properties were monitoring using the Emulsifying Activity Index (EAI and Emulsion Stability (ES. In addition, gel pastes were formulated from the squid mantle, weakfish muscle and the mixture of both species, and the following functional properties of the gels assessed: water holding capacity, colour, textural profile analysis (TPA (hardness, elasticity, cohesiveness, gumminess and gel strength. The EAI values of emulsions formulated with the MF of the mantle were significantly (p<0.05 higher than those formulated from those of weakfish. The incorporation of squid MF in the mixture increased the EAI values. Conversely, the highest ES values were obtained with weakfish MF, and the incorporation of MF weakfish in the mixture increased the ES values. Similar EAI and ES behaviours were observed for the AM of the corresponding species. Irrespective of the thermal treatment, the gel strength of the gelled paste of squid muscle was significantly (p<0.05 lower than that of weakfish muscle and of those obtained with the different mixtures. The behaviours of the expressible moisture (EM from the gelled pastes were similar to those of gel strength. Irrespective of the thermal treatment, the pastes formulated with a high weakfish: mantle ratio showed less water loss. The gelled pastes of squid mantle showed the highest values for whiteness

Chymase inhibition prevents fibronectin and myofibrillar loss and improves cardiomyocyte function and LV torsion angle in dogs with isolated mitral regurgitation.

Science.gov (United States)

Pat, Betty; Chen, Yuanwen; Killingsworth, Cheryl; Gladden, James D; Shi, Ke; Zheng, Junying; Powell, Pamela C; Walcott, Greg; Ahmed, Mustafa I; Gupta, Himanshu; Desai, Ravi; Wei, Chih-Chang; Hase, Naoki; Kobayashi, Tsunefumi; Sabri, Abdelkarim; Granzier, Henk; Denney, Thomas; Tillson, Michael; Dillon, A Ray; Husain, Ahsan; Dell'italia, Louis J

2010-10-12

The left ventricular (LV) dilatation of isolated mitral regurgitation (MR) is associated with an increase in chymase and a decrease in interstitial collagen and extracellular matrix. In addition to profibrotic effects, chymase has significant antifibrotic actions because it activates matrix metalloproteinases and kallikrein and degrades fibronectin. Thus, we hypothesize that chymase inhibitor (CI) will attenuate extracellular matrix loss and LV remodeling in MR. We studied dogs with 4 months of untreated MR (MR; n=9) or MR treated with CI (MR+CI; n=8). Cine MRI demonstrated a >40% increase in LV end-diastolic volume in both groups, consistent with a failure of CI to improve a 25% decrease in interstitial collagen in MR. However, LV cardiomyocyte fractional shortening was decreased in MR versus normal dogs (3.71±0.24% versus 4.81±0.31%; P<0.05) and normalized in MR+CI dogs (4.85±0.44%). MRI with tissue tagging demonstrated an increase in LV torsion angle in MR+CI versus MR dogs. CI normalized the significant decrease in fibronectin and FAK phosphorylation and prevented cardiomyocyte myofibrillar degeneration in MR dogs. In addition, total titin and its stiffer isoform were increased in the LV epicardium and paralleled the changes in fibronectin and FAK phosphorylation in MR+CI dogs. These results suggest that chymase disrupts cell surface-fibronectin connections and FAK phosphorylation that can adversely affect cardiomyocyte myofibrillar structure and function. The greater effect of CI on epicardial versus endocardial titin and noncollagen cell surface proteins may be responsible for the increase in torsion angle in chronic MR.

Differences in postprandial protein handling after beef compared with milk ingestion during postexercise recovery: a randomized controlled trial.

Science.gov (United States)

Burd, Nicholas A; Gorissen, Stefan H; van Vliet, Stephan; Snijders, Tim; van Loon, Luc Jc

2015-10-01

Protein consumed after resistance exercise increases postexercise muscle protein synthesis rates. To date, dairy protein has been studied extensively, with little known about the capacity of other protein-dense foods to augment postexercise muscle protein synthesis rates. We aimed to compare protein digestion and absorption kinetics, postprandial amino acid availability, anabolic signaling, and the subsequent myofibrillar protein synthetic response after the ingestion of milk compared with beef during recovery from resistance-type exercise. In crossover trials, 12 healthy young men performed a single bout of resistance exercise. Immediately after cessation of exercise, participants ingested 30 g protein by consuming isonitrogenous amounts of intrinsically l-[1-(13)C]phenylalanine-labeled beef or milk. Blood and muscle biopsy samples were collected at rest and after exercise during primed continuous infusions of l-[ring-(2)H5]phenylalanine and l-[ring-3,5-(2)H2]tyrosine to assess protein digestion and absorption kinetics, plasma amino acid availability, anabolic signaling, and subsequent myofibrillar protein synthesis rates in vivo in young men. Beef protein-derived phenylalanine appeared more rapidly in circulation compared with milk ingestion (P Nutrition.

Inhibition of ErbB2 by receptor tyrosine kinase inhibitors causes myofibrillar structural damage without cell death in adult rat cardiomyocytes

International Nuclear Information System (INIS)

Pentassuglia, Laura; Graf, Michael; Lane, Heidi; Kuramochi, Yukio; Cote, Gregory; Timolati, Francesco; Sawyer, Douglas B.; Zuppinger, Christian; Suter, Thomas M.

2009-01-01

Inhibition of ErbB2 (HER2) with monoclonal antibodies, an effective therapy in some forms of breast cancer, is associated with cardiotoxicity, the pathophysiology of which is poorly understood. Recent data suggest, that dual inhibition of ErbB1 (EGFR) and ErbB2 signaling is more efficient in cancer therapy, however, cardiac safety of this therapeutic approach is unknown. We therefore tested an ErbB1-(CGP059326) and an ErbB1/ErbB2-(PKI166) tyrosine kinase inhibitor in an in-vitro system of adult rat ventricular cardiomyocytes and assessed their effects on 1. cell viability, 2. myofibrillar structure, 3. contractile function, and 4. MAPK- and Akt-signaling alone or in combination with Doxorubicin. Neither CGP nor PKI induced cardiomyocyte necrosis or apoptosis. PKI but not CGP caused myofibrillar structural damage that was additive to that induced by Doxorubicin at clinically relevant doses. These changes were associated with an inhibition of excitation-contraction coupling. PKI but not CGP decreased p-Erk1/2, suggesting a role for this MAP-kinase signaling pathway in the maintenance of myofibrils. These data indicate that the ErbB2 signaling pathway is critical for the maintenance of myofibrillar structure and function. Clinical studies using ErbB2-targeted inhibitors for the treatment of cancer should be designed to include careful monitoring for cardiac dysfunction.

On protein quality control, myofibrillar myopathies, and neurodegeneration

NARCIS (Netherlands)

Meister, Melanie

2017-01-01

Eiwitten zijn bouwstenen van de cel en het is noodzakelijk dat zij in specifieke -vooraf bepaalde – 3-dimensionale vormen ‘gevouwen’ worden om hun functies binnen de cel te kunnen vervullen. De cel heeft een speciaal netwerk (Protein Quality Control [PQC] netwerk) die de kwaliteit van dergelijke

Mechanosensitive molecular networks involved in transducing resistance exercise-signals into muscle protein accretion

Directory of Open Access Journals (Sweden)

Emil Rindom

2016-11-01

Full Text Available Loss of skeletal muscle myofibrillar protein with disease and/or inactivity can severely deteriorate muscle strength and function. Strategies to counteract wasting of muscle myofibrillar protein are therefore desirable and invite for considerations on the potential superiority of specific modes of resistance exercise and/or the adequacy of low load resistance exercise regimens as well as underlying mechanisms. In this regard, delineation of the potentially mechanosensitive molecular mechanisms underlying muscle protein synthesis (MPS, may contribute to understanding on how differentiated resistance exercise can transduce a mechanical signal into stimulation of muscle accretion. Recent findings suggest specific upstream exercise-induced mechano-sensitive myocellular signaling pathways to converge on mammalian target of rapamycin complex 1 (mTORC1, to influence MPS. This may e.g. implicate mechanical activation of signaling through a diacylglycerol kinase (DGKζ-phosphatidic acid (PA axis or implicate integrin deformation to signal through a Focal adhesion kinase (FAK-Tuberous Sclerosis Complex 2TSC2-Ras homolog enriched in brain (Rheb axis. Moreover, since initiation of translation is reliant on mRNA, it is also relevant to consider potentially mechanosensitive signaling pathways involved in muscle myofibrillar gene transcription and whether some of these pathways converge with those affecting mTORC1 activation for MPS. In this regard, recent findings suggest how mechanical stress may implicate integrin deformation and/or actin dynamics to signal through a Ras homolog gene family member A protein (RhoA-striated muscle activator of Rho signaling (STARS axis or how it may implicate deformation of Notch to affect Bone Morphogenetic Protein (BMP signaling through a small mother of decapentaplegic (Smad axis.

Anabolic sensitivity of postprandial muscle protein synthesis to the ingestion of a protein-dense food is reduced in overweight and obese young adults.

Science.gov (United States)

Beals, Joseph W; Sukiennik, Richard A; Nallabelli, Julian; Emmons, Russell S; van Vliet, Stephan; Young, Justin R; Ulanov, Alexander V; Li, Zhong; Paluska, Scott A; De Lisio, Michael; Burd, Nicholas A

2016-10-01

Excess body fat diminishes muscle protein synthesis rates in response to hyperinsulinemic-hyperaminoacidemic clamps. However, muscle protein synthetic responses after the ingestion of a protein-dense food source across a range of body mass indexes (BMIs) have not been compared. We compared the myofibrillar protein synthetic response and underlying nutrient-sensing mechanisms after the ingestion of lean pork between obese, overweight, and healthy-weight adults. Ten healthy-weight [HW; BMI (in kg/m 2 ): 22.7 ± 0.4], 10 overweight (OW; BMI: 27.1 ± 0.5), and 10 obese (OB; BMI: 35.9 ± 1.3) adults received primed continuous l-[ring- 13 C 6 ]phenylalanine infusions. Blood and muscle biopsy samples were collected before and after the ingestion of 170 g pork (36 g protein and 3 g fat) to assess skeletal muscle anabolic signaling, amino acid transporters [large neutral and small neutral amino acid transporters (LAT1, SNAT2) and CD98], and myofibrillar protein synthesis. At baseline, OW and OB groups showed greater relative amounts of mammalian target of rapamycin complex 1 (mTORC1) protein than the HW group. Pork ingestion increased mTORC1 phosphorylation only in the HW group (P = 0.001). LAT1 and SNAT2 protein content increased during the postprandial period in all groups (time effect, P anabolic signals, that reduces muscle sensitivity to food ingestion. This trial was registered at clinicaltrials.gov as NCT02613767. © 2016 American Society for Nutrition.

High frequency breakdown voltage

International Nuclear Information System (INIS)

Chu, Thanh Duy.

1992-03-01

This report contains information about the effect of frequency on the breakdown voltage of an air gap at standard pressure and temperature, 76 mm Hg and O degrees C, respectively. The frequencies of interest are 47 MHz and 60 MHz. Additionally, the breakdown in vacuum is briefly considered. The breakdown mechanism is explained on the basis of collision and ionization. The presence of the positive ions produced by ionization enhances the field in the gap, and thus determines the breakdown. When a low-frequency voltage is applied across the gap, the breakdown mechanism is the same as that caused by the DC or static voltage. However, when the frequency exceeds the first critical value f c , the positive ions are trapped in the gap, increasing the field considerably. This makes the breakdown occur earlier; in other words, the breakdown voltage is lowered. As the frequency increases two decades or more, the second critical frequency, f ce , is reached. This time the electrons start being trapped in the gap. Those electrons that travel multiple times across the gap before reaching the positive electrode result in an enormous number of electrons and positive ions being present in the gap. The result is a further decrease of the breakdown voltage. However, increasing the frequency does not decrease the breakdown voltage correspondingly. In fact, the associated breakdown field intensity is almost constant (about 29 kV/cm).The reason is that the recombination rate increases and counterbalances the production rate, thus reducing the effect of the positive ions' concentration in the gap. The theory of collision and ionization does not apply to the breakdown in vacuum. It seems that the breakdown in vacuum is primarily determined by the irregularities on the surfaces of the electrodes. Therefore, the effect of frequency on the breakdown, if any, is of secondary importance

Nuclear envelope breakdown induced by herpes simplex virus type 1 involves the activity of viral fusion proteins.

Science.gov (United States)

Maric, Martina; Haugo, Alison C; Dauer, William; Johnson, David; Roller, Richard J

2014-07-01

Herpesvirus infection reorganizes components of the nuclear lamina usually without loss of integrity of the nuclear membranes. We report that wild-type HSV infection can cause dissolution of the nuclear envelope in transformed mouse embryonic fibroblasts that do not express torsinA. Nuclear envelope breakdown is accompanied by an eight-fold inhibition of virus replication. Breakdown of the membrane is much more limited during infection with viruses that lack the gB and gH genes, suggesting that breakdown involves factors that promote fusion at the nuclear membrane. Nuclear envelope breakdown is also inhibited during infection with virus that does not express UL34, but is enhanced when the US3 gene is deleted, suggesting that envelope breakdown may be enhanced by nuclear lamina disruption. Nuclear envelope breakdown cannot compensate for deletion of the UL34 gene suggesting that mixing of nuclear and cytoplasmic contents is insufficient to bypass loss of the normal nuclear egress pathway. Copyright © 2014 Elsevier Inc. All rights reserved.

Methodical investigation of the protein metabolism and of the bioenergetics of protein retention in growing animals. 1

International Nuclear Information System (INIS)

Schiemann, R.; Bock, H.D.; Keller, J.; Hoffmann, L.; Krawielitzki, K.; Klein, M.

1983-01-01

The influence of different protein levels in the feed (group R1 20%, R2 38% crude protein) and of different energy levels (group J1 low, J2 high energy level) on the composition of the carcass and the apparent half-life periods of the body proteins were determined in 4 groups of 15 male broiler chickens labelled with 15 NH 4 acetate. In all slaughtering phases the higher protein level resulted in a higher weight of the feathers, breast and leg muscles, higher amounts of N in all parts of the body and a higher percentage of feathers, breast and leg muscles of the total carcass than the lower protein level. Between 13 and 19% of the N in the carcass contributed to the feathers, 24-31% to the breast and leg muscles and 50-63% to the rest of the carcass. The relative quotas of the sum of breast and leg muscles in the carcass were higher for the low energy level than for the high energy level. There were no remarkable differences as to the protein content of the muscles in dependence on the energy level, the quota of sarcoplasmatic proteins, however, was higher on the high level in contrast to the low energy level, that of the myofibrillar proteins was lower. The apparent half-life period of the total body protein after normal protein supply was 22 days (group R1) and 14 after high protein supply. The energy levels in groups J1 and J2 had no significant influence on the half-life period of the total body protein. In the body fractions examined the apparent half-life periods were highest in the breast muscle and lowest in the rest of the carcass. The protein stored in the feathers did not undergo decomposition. The protein fractions 'sarcoplasmatic protein' and 'myofibrillar protein' of breast and leg muscle neither differed from one another nor from the respective total muscle fractions as regards their half-life period. (author)

Towards generation of bioactive peptides from meat industry waste proteins: Generation of peptides using commercial microbial proteases.

Science.gov (United States)

Ryder, Kate; Bekhit, Alaa El-Din; McConnell, Michelle; Carne, Alan

2016-10-01

Five commercially available food-grade microbial protease preparations were evaluated for their ability to hydrolyse meat myofibrillar and connective tissue protein extracts to produce bioactive peptides. A bacterial-derived protease (HT) extensively hydrolysed both meat protein extracts, producing peptide hydrolysates with significant in vitro antioxidant and ACE inhibitor activities. The hydrolysates retained bioactivity after simulated gastrointestinal hydrolysis challenge. Gel permeation chromatography sub-fractionation of the crude protein hydrolysates showed that the smaller peptide fractions exhibited the highest antioxidant and ACE inhibitor activities. OFFGEL electrophoresis of the small peptides of both hydrolysates showed that low isoelectric point peptides had antioxidant activity; however, no consistent relationship was observed between isoelectric point and ACE inhibition. Cell-based assays indicated that the hydrolysates present no significant cytotoxicity towards Vero cells. The results indicate that HT protease hydrolysis of meat myofibrillar and connective tissue protein extracts produces bioactive peptides that are non-cytotoxic, should be stable in the gastrointestinal tract and may contain novel bioactive peptide sequences. Copyright © 2016 Elsevier Ltd. All rights reserved.

Angiotensin I-Converting Enzyme (ACE Inhibitory Activity and ACE Inhibitory Peptides of Salmon (Salmo salar Protein Hydrolysates Obtained by Human and Porcine Gastrointestinal Enzymes

Directory of Open Access Journals (Sweden)

Małgorzata Darewicz

2014-08-01

Full Text Available The objectives of the present study were two-fold: first, to detect whether salmon protein fractions possess angiotensin I-converting enzyme (ACE inhibitory properties and whether salmon proteins can release ACE inhibitory peptides during a sequential in vitro hydrolysis (with commercial porcine enzymes and ex vivo digestion (with human gastrointestinal enzymes. Secondly, to evaluate the ACE inhibitory activity of generated hydrolysates. A two-step ex vivo and in vitro model digestion was performed to simulate the human digestion process. Salmon proteins were degraded more efficiently by porcine enzymes than by human gastrointestinal juices and sarcoplasmic proteins were digested/hydrolyzed more easily than myofibrillar proteins. The ex vivo digested myofibrillar and sarcoplasmic duodenal samples showed IC50 values (concentration required to decrease the ACE activity by 50% of 1.06 and 2.16 mg/mL, respectively. The in vitro hydrolyzed myofibrillar and sarcoplasmic samples showed IC50 values of 0.91 and 1.04 mg/mL, respectively. Based on the results of in silico studies, it was possible to identify 9 peptides of the ex vivo hydrolysates and 7 peptides of the in vitro hydrolysates of salmon proteins of 11 selected peptides. In both types of salmon hydrolysates, ACE-inhibitory peptides IW, IY, TVY and VW were identified. In the in vitro salmon protein hydrolysates an ACE-inhibitory peptides VPW and VY were also detected, while ACE-inhibitory peptides ALPHA, IVY and IWHHT were identified in the hydrolysates generated with ex vivo digestion. In our studies, we documented ACE inhibitory in vitro effects of salmon protein hydrolysates obtained by human and as well as porcine gastrointestinal enzymes.

Ingestion of Wheat Protein Increases In Vivo Muscle Protein Synthesis Rates in Healthy Older Men in a Randomized Trial.

Science.gov (United States)

Gorissen, Stefan Hm; Horstman, Astrid Mh; Franssen, Rinske; Crombag, Julie Jr; Langer, Henning; Bierau, Jörgen; Respondek, Frederique; van Loon, Luc Jc

2016-09-01

Muscle mass maintenance is largely regulated by basal muscle protein synthesis and the capacity to stimulate muscle protein synthesis after food intake. The postprandial muscle protein synthetic response is modulated by the amount, source, and type of protein consumed. It has been suggested that plant-based proteins are less potent in stimulating postprandial muscle protein synthesis than animal-derived proteins. However, few data support this contention. We aimed to assess postprandial plasma amino acid concentrations and muscle protein synthesis rates after the ingestion of a substantial 35-g bolus of wheat protein hydrolysate compared with casein and whey protein. Sixty healthy older men [mean ± SEM age: 71 ± 1 y; body mass index (in kg/m(2)): 25.3 ± 0.3] received a primed continuous infusion of l-[ring-(13)C6]-phenylalanine and ingested 35 g wheat protein (n = 12), 35 g wheat protein hydrolysate (WPH-35; n = 12), 35 g micellar casein (MCas-35; n = 12), 35 g whey protein (Whey-35; n = 12), or 60 g wheat protein hydrolysate (WPH-60; n = 12). Plasma and muscle samples were collected at regular intervals. The postprandial increase in plasma essential amino acid concentrations was greater after ingesting Whey-35 (2.23 ± 0.07 mM) than after MCas-35 (1.53 ± 0.08 mM) and WPH-35 (1.50 ± 0.04 mM) (P protein synthesis rates increased after ingesting MCas-35 (P protein synthesis rates above basal rates (0.049% ± 0.007%/h; P = 0.02). The myofibrillar protein synthetic response to the ingestion of 35 g casein is greater than after an equal amount of wheat protein. Ingesting a larger amount of wheat protein (i.e., 60 g) substantially increases myofibrillar protein synthesis rates in healthy older men. This trial was registered at clinicaltrials.gov as NCT01952639. © 2016 American Society for Nutrition.

Antioxidant properties of salmon (Salmo salar L.) protein fraction hydrolysates revealed following their ex vivo digestion and in vitro hydrolysis.

Science.gov (United States)

Borawska, Justyna; Darewicz, Małgorzata; Pliszka, Monika; Vegarud, Gerd E

2016-06-01

Salmon (Salmo salar L.) myofibryllar protein (MP) and sarcoplasmic protein (SP) were digested with human gastric and duodenal juices and hydrolysed in vitro with commercial pepsin and Corolase PP. The digestion after duodenal juice/Corolase PP caused almost complete breakdown of peptide bonds in MP and SP. The DPPH(•) scavenging activity of proteins decreased during both ex vivo digestion and in vitro hydrolysis. The highest value of DPPH(•) scavenging activity was shown for the gastric digest of SP (8.88 ± 0.87%). The ABTS(+•) scavenging activity of MP and SP increased during digestion/hydrolysis. The duodenal digest of SP was characterised by the highest value of ABTS(+•) scavenging activity (72.7 ± 1.2%). In turn, the highest value of ferric-reducing power was determined for the gastric digest of SP (84.8 ± 0.2%). Salmon antioxidant peptides Phe-Ile-Lys-Lys, His-Leu, Ile-Tyr, Pro-His-Leu, Pro-Trp, Val-Pro-Trp were identified in both ex vivo digested and in vitro hydrolysed MP and SP. An antioxidant peptide, Val-Tyr, was additionally detected in the in vitro hydrolysate of SP. The results indicate the salmon myofibrillar and sarcoplasmic protein fractions as potential sources of antioxidant peptides that could be released in the gastrointestinal tract but their amino acid sequence and quantification vary. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

High pressure processing of meat

DEFF Research Database (Denmark)

Grossi, Alberto; Christensen, Mette; Ertbjerg, Per

the rheological properties of pork meat batters by inducing formation of protein gels. HP induced protein gels are suggested to be formed by high molecular weight myofibrillar protein aggregates and by peptides formed by lysosomal enzyme-induced cleavage of myofibrillar proteins. Perspectives: The data presented...

Investigating the role of uncoupling of Troponin I phosphorylation from changes in myofibrillar Ca2+-sensitivity in the pathogenesis of Cardiomyopathy

Directory of Open Access Journals (Sweden)

Andrew Easton Messer

2014-08-01

Full Text Available Contraction in the mammalian heart is controlled by the intracellular Ca2+ concentration as it is in all striated muscle, but the heart has an additional signalling system that comes into play to increase heart rate and cardiac output during exercise or stress. β-adrenergic stimulation of heart muscle cells leads to release of cyclic-AMP and the activation of protein kinase A which phosphorylates key proteins in the sarcolemma, sarcoplasmic reticulum and contractile apparatus. Troponin I (TnI and Myosin Binding Protein C (MyBP-C are the prime targets in the myofilaments. TnI phosphorylation lowers myofibrillar Ca2+-sensitivity and increases the speed of Ca2+-dissociation and relaxation (lusitropic effect.Recent studies have shown that this relationship between Ca2+-sensitivity and TnI phosphorylation may be unstable. In familial cardiomyopathies, both dilated and hypertrophic (DCM and HCM, a mutation in one of the proteins of the thin filament often results in the loss of the relationship (uncoupling and blunting of the lusitropic response. For familial dilated cardiomyopathy in thin filament proteins it has been proposed that this uncoupling is causative of the phenotype. Uncoupling has also been found in human heart tissue from patients with hypertrophic obstructive cardiomyopathy as a secondary effect. Recently, it has been found that Ca2+-sensitizing drugs can promote uncoupling, whilst one Ca2+-desensitising drug Epigallocatechin 3-Gallate (EGCG can reverse uncoupling.We will discuss recent findings about the role of uncoupling in the development of cardiomyopathies and the molecular mechanism of the process.

dc breakdown conditioning and breakdown rate of metals and metallic alloys under ultrahigh vacuum

CERN Document Server

Descoeudres, A; Calatroni, S; Taborelli, M; Wuensch, W

2009-01-01

RF accelerating structures of the Compact Linear Collider (CLIC) require a material capable of sustaining high electric field with a low breakdown rate and low induced damage. Because of the similarity of many aspects of DC and RF breakdown, a DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultra-high vacuum in a simple setup. Conditioning speeds and breakdown fields of several metals and alloys have been measured. The average breakdown field after conditioning ranges from 100 MV/m for Al to 850 MV/m for stainless steel, and is around 170 MV/m for Cu which is the present base-line material for CLIC structures. The results indicate clearly that the breakdown field is limited by the cathode. The presence of a thin cuprous oxide film at the surface of copper electrodes significantly increases the breakdown field. On the other hand, the conditioning speed of Mo is improved by removing oxides at t...

dc breakdown conditioning and breakdown rate of metals and metallic alloys under ultrahigh vacuum

Directory of Open Access Journals (Sweden)

A. Descoeudres

2009-03-01

Full Text Available The rf accelerating structures of the Compact Linear Collider (CLIC require a material capable of sustaining high electric field with a low breakdown rate and low induced damage. Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultrahigh vacuum in a simple setup. Conditioning speeds and breakdown fields of several metals and alloys have been measured. The average breakdown field after conditioning ranges from 100  MV/m for Al to 850  MV/m for stainless steel, and is around 170  MV/m for Cu which is the present base-line material for CLIC structures. The results indicate clearly that the breakdown field is limited by the cathode. The presence of a thin cuprous oxide film at the surface of copper electrodes significantly increases the breakdown field. On the other hand, the conditioning speed of Mo is improved by removing oxides at the surface with a vacuum heat treatment, typically at 875°C for 2 hours. Surface finishing treatments of Cu samples only affect the very first breakdowns. More generally, surface treatments have an effect on the conditioning process itself, but not on the average breakdown field reached after the conditioning phase. In analogy to rf, the breakdown probability has been measured in dc with Cu and Mo electrodes. The dc data show similar behavior as rf as a function of the applied electric field.

Protein turnover, amino acid requirements and recommendations for athletes and active populations

Energy Technology Data Exchange (ETDEWEB)

Poortmans, J.R.; Carpentier, A. [Laboratory for Biometry and Sport Nutrition, Faculty of Motor Sciences, Free University of Brussels, Brussels (Belgium); Pereira-Lancha, L.O. [Departamento de Nutrição, Instituto Vita, São Paulo, SP (Brazil); Lancha, A. Jr. [Laboratório de Nutrição Aplicada à Atividade Motora, Escola de Educação Física e Esporte, Universidade de São Paulo, São Paulo, SP (Brazil)

2012-06-08

Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ({sup 13}C-lysine, {sup 15}N-glycine, {sup 2}H{sub 5}-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg{sup −1}·day{sup −1} compared to 0.8 g·kg{sup −1}·day{sup −1} in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

Protein turnover, amino acid requirements and recommendations for athletes and active populations

International Nuclear Information System (INIS)

Poortmans, J.R.; Carpentier, A.; Pereira-Lancha, L.O.; Lancha, A. Jr.

2012-01-01

Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ( 13 C-lysine, 15 N-glycine, 2 H 5 -phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg −1 ·day −1 compared to 0.8 g·kg −1 ·day −1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h

Protein turnover, amino acid requirements and recommendations for athletes and active populations

Directory of Open Access Journals (Sweden)

J.R. Poortmans

2012-10-01

Full Text Available Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers (13C-lysine, 15N-glycine, ²H5-phenylalanine and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes compared to resistance exercise, which induces fiber hypertrophy (myofibrils. Nitrogen balance (difference between protein intake and protein degradation for athletes is usually balanced when the intake of protein reaches 1.2 g·kg-1·day-1 compared to 0.8 g·kg-1·day-1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins and carbohydrate (± 30 g maltodextrine drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

Electrical breakdown in vacuum

International Nuclear Information System (INIS)

Beukema, G.P.

1980-01-01

The main part of this thesis is dedicated to the field enhancement factor; in particular to the study of the origin, alteration and influence on the breakdown properties of different materials. This work required the examination of large surface areas on the same microscopic scale on which the relevant phenomena occur. (Pre)-breakdown measurements are described in which the anode condition does not play a role in the initiation of a breakdown, while the cathode can be considered as a broad-area electrode. The influence of adsorbed gases on pre-breakdown currents is investigated. It is shown that ions, released by field emission electrons from adsorbed layers on the anode change the emitting properties of a well-conditioned cathode if the current density at the anode is small. A new experimental arrangement is outlined to better distinguish between the different parameters which are important for the initiation of electrical breakdown. Comparative measurements between stainless steel and titanium electrodes are described to study the influence of either the cathode or the anode upon the initiation of a breakdown. (Auth.)

Galalpha1-->4Gal-glycans are expressed on myofibrillar associated proteins

DEFF Research Database (Denmark)

Kirkeby, S; Moe, D; Cläesson, M H

1998-01-01

NAcbeta- were used to detect terminal alpha-galactosylated glycoconjugates on muscle proteins. Electrotransfer of proteins, extracted from human masseter and biceps muscles, to nitrocellulose after polyacrylamide gel electrophoresis (PAGE) and incubation with anti-Pk (CD77) consistently showed two bands...... with apparent molecular weights of 66 kDa and 64 kDa. In fresh frozen muscle sections from some humans there was endothelial reaction with anti-CD77 in capillaries, venules and veins but not in arterioles and arteries. In muscle samples from other humans there was no staining of endothelial cells. Formalin......-fixed human muscle displayed a CD77 reaction with highest accumulation of reaction product at the periphery of the fibers. This may be explained by the presence of Pk glycoconjugates on intermediate filaments in muscle fibers. In preparations of cat masseter muscle proteins the antibodies against P1Pk...

Breakdowns in collaborative information seeking

DEFF Research Database (Denmark)

Hertzum, Morten

2010-01-01

Collaborative information seeking is integral to many professional activities. In hospital work, the medication process encompasses continual seeking for information and collaborative grounding of information. This study investigates breakdowns in collaborative information seeking through analyses...... of the use of the electronic medication record adopted in a Danish healthcare region and of the reports of five years of medication incidents at Danish hospitals. The results show that breakdowns in collaborative information seeking is a major source of medication incidents, that most of these breakdowns...... are breakdowns in collaborative grounding rather than information seeking, that the medication incidents mainly concern breakdowns in the use of records as opposed to oral communication, that the breakdowns span multiple degrees of separation between clinicians, and that the electronic medication record has...

Methodical investigation of the protein metabolism and of the bioenergetics of protein retention in growing animals. 1. Determination of parameters of growth and protein retention of chickens after long-term labelling with /sup 15/NH/sub 4/ acetate

Energy Technology Data Exchange (ETDEWEB)

Schiemann, R.; Bock, H.D.; Keller, J.; Hoffmann, L.; Krawielitzki, K.; Klein, M. (Akademie der Landwirtschaftswissenschaften der DDR, Dummerstorf-Rostock. Forschungszentrum fuer Tierproduktion)

1983-01-01

The influence of different protein levels in the feed (group R1 20%, R2 38% crude protein) and of different energy levels (group J1 low, J2 high energy level) on the composition of the carcass and the apparent half-life periods of the body proteins were determined in 4 groups of 15 male broiler chickens labelled with /sup 15/NH/sub 4/ acetate. In all slaughtering phases the higher protein level resulted in a higher weight of the feathers, breast and leg muscles, higher amounts of N in all parts of the body and a higher percentage of feathers, breast and leg muscles of the total carcass than the lower protein level. Between 13 and 19% of the N in the carcass contributed to the feathers, 24-31% to the breast and leg muscles and 50-63% to the rest of the carcass. The relative quotas of the sum of breast and leg muscles in the carcass were higher for the low energy level than for the high energy level. There were no remarkable differences as to the protein content of the muscles in dependence on the energy level, the quota of sarcoplasmatic proteins, however, was higher on the high level in contrast to the low energy level, that of the myofibrillar proteins was lower. The apparent half-life period of the total body protein after normal protein supply was 22 days (group R1) and 14 after high protein supply. The energy levels in groups J1 and J2 had no significant influence on the half-life period of the total body protein. In the body fractions examined the apparent half-life periods were highest in the breast muscle and lowest in the rest of the carcass. The protein stored in the feathers did not undergo decomposition. The protein fractions 'sarcoplasmatic protein' and 'myofibrillar protein' of breast and leg muscle neither differed from one another nor from the respective total muscle fractions as regards their half-life period.

Consumption of Milk Protein or Whey Protein Results in a Similar Increase in Muscle Protein Synthesis in Middle Aged Men.

Science.gov (United States)

Mitchell, Cameron J; McGregor, Robin A; D'Souza, Randall F; Thorstensen, Eric B; Markworth, James F; Fanning, Aaron C; Poppitt, Sally D; Cameron-Smith, David

2015-10-21

The differential ability of various milk protein fractions to stimulate muscle protein synthesis (MPS) has been previously described, with whey protein generally considered to be superior to other fractions. However, the relative ability of a whole milk protein to stimulate MPS has not been compared to whey. Sixteen healthy middle-aged males ingested either 20 g of milk protein (n = 8) or whey protein (n = 8) while undergoing a primed constant infusion of ring (13)C₆ phenylalanine. Muscle biopsies were obtained 120 min prior to consumption of the protein and 90 and 210 min afterwards. Resting myofibrillar fractional synthetic rates (FSR) were 0.019% ± 0.009% and 0.021% ± 0.018% h(-1) in the milk and whey groups respectively. For the first 90 min after protein ingestion the FSR increased (p whey groups respectively with no difference between groups (p = 0.810). FSR returned to baseline in both groups between 90 and 210 min after protein ingestion. Despite evidence of increased rate of digestion and leucine availability following the ingestion of whey protein, there was similar activation of MPS in middle-aged men with either 20 g of milk protein or whey protein.

Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men.

Science.gov (United States)

van Vliet, Stephan; Shy, Evan L; Abou Sawan, Sidney; Beals, Joseph W; West, Daniel Wd; Skinner, Sarah K; Ulanov, Alexander V; Li, Zhong; Paluska, Scott A; Parsons, Carl M; Moore, Daniel R; Burd, Nicholas A

2017-12-01

Background: Protein in the diet is commonly ingested from whole foods that contain various macro- and micronutrients. However, the effect of consuming protein within its natural whole-food matrix on postprandial protein metabolism remains understudied in humans. Objective: We aimed to compare the whole-body and muscle protein metabolic responses after the consumption of whole eggs with egg whites during exercise recovery in young men. Design: In crossover trials, 10 resistance-trained men [aged 21 ± 1 y; 88 ± 3 kg; body fat: 16% ± 1% (means ± SEMs)] received primed continuous l-[ ring - 2 H 5 ]phenylalanine and l-[1- 13 C]leucine infusions and performed a single bout of resistance exercise. After exercise, participants consumed intrinsically l-[5,5,5- 2 H 3 ]leucine-labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Repeated blood and muscle biopsy samples were collected to assess whole-body leucine kinetics, intramuscular signaling, and myofibrillar protein synthesis. Results: Plasma appearance rates of protein-derived leucine were more rapid after the consumption of egg whites than after whole eggs ( P = 0.01). Total plasma availability of leucine over the 300-min postprandial period was similar ( P = 0.75) between the ingestion of whole eggs (68% ± 1%) and egg whites (66% ± 2%), with no difference in whole-body net leucine balance ( P = 0.27). Both whole-egg and egg white conditions increased the phosphorylation of mammalian target of rapamycin complex 1, ribosomal protein S6 kinase 1, and eukaryotic translation initiation factor 4E-binding protein 1 during postexercise recovery (all P egg ingestion increased the postexercise myofibrillar protein synthetic response to a greater extent than did the ingestion of egg whites ( P = 0.04). Conclusions: We show that the ingestion of whole eggs immediately after resistance exercise resulted in greater stimulation of myofibrillar protein synthesis than did the ingestion of egg whites

AC BREAKDOWN IN GASES

Science.gov (United States)

electron- emission (multipactor) region, and (3) the low-frequency region. The breakdown mechanism in each of these regions is explained. An extensive bibliography on AC breakdown in gases is included.

Cave breakdown by vadose weathering.

Directory of Open Access Journals (Sweden)

Osborne R. Armstrong L.

2002-01-01

Full Text Available Vadose weathering is a significant mechanism for initiating breakdown in caves. Vadose weathering of ore bodies, mineral veins, palaeokarst deposits, non-carbonate keystones and impure, altered or fractured bedrock, which is intersected by caves, will frequently result in breakdown. Breakdown is an active, ongoing process. Breakdown occurs throughout the vadose zone, and is not restricted to large diameter passages, or to cave ceilings. The surfaces of disarticulated blocks are commonly coated, rather than having fresh broken faces, and blocks continue to disintegrate after separating from the bedrock. Not only gypsum, but also hydromagnesite and aragonite are responsible for crystal wedging. It is impossible to study or identify potential breakdown foci by surface surveys alone, in-cave observation and mapping are essential.

Proteomic analysis of processing by-products from canned and fresh tuna: identification of potentially functional food proteins.

Science.gov (United States)

Sanmartín, Esther; Arboleya, Juan Carlos; Iloro, Ibon; Escuredo, Kepa; Elortza, Felix; Moreno, F Javier

2012-09-15

Proteomic approaches have been used to identify the main proteins present in processing by-products generated by the canning tuna-industry, as well as in by-products derived from filleting of skeletal red muscle of fresh tuna. Following fractionation by using an ammonium sulphate precipitation method, three proteins (tropomyosin, haemoglobin and the stress-shock protein ubiquitin) were identified in the highly heterogeneous and heat-treated material discarded by the canning-industry. Additionally, this fractionation method was successful to obtain tropomyosin of high purity from the heterogeneous starting material. By-products from skeletal red muscle of fresh tuna were efficiently fractionated to sarcoplasmic and myofibrillar fractions, prior to the identification based mainly on the combined searching of the peptide mass fingerprint (MALDI-TOF) and peptide fragment fingerprinting (MALDI LIFT-TOF/TOF) spectra of fifteen bands separated by 1D SDS-PAGE. Thus, the sarcoplasmic fraction contained myoglobin and several enzymes that are essential for efficient energy production, whereas the myofibrillar fraction had important contractile proteins, such as actin, tropomyosin, myosin or an isoform of the enzyme creatine kinase. Application of proteomic technologies has revealed new knowledge on the composition of important by-products from tuna species, enabling a better evaluation of their potential applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

["Nervous breakdown": a diagnostic characterization study].

Science.gov (United States)

Salmán, E; Carrasco, J L; Liebowitz, M; Díaz Marsá, M; Prieto, R; Jusino, C; Cárdenas, D; Klein, D

1997-01-01

An evaluation was made of the influence of different psychiatric co-morbidities on the symptoms of the disorder popularly known as "ataque de nervios" (nervous breakdown) among the US Hispanic population. Using a self-completed instrument designed specially for both traditional nervous breakdown and for panic symptoms, and structured or semi-structured psychiatric interviews for Axis I disorders, and evaluation was made of Hispanic subjects who sought treatment for anxiety in a clinic (n = 156). This study centered on 102 subjects who presented symptoms of "nervous breakdown" and comorbidity with panic disorder, other anxiety disorders, or affective disorder. Variations in co-morbidity with "nervous breakdown" enabled the identification of different patterns of "nervous breakdown" presenting symptoms. Individuals with "nervous breakdown" and panic disorder characteristically expressed a greater sense of asphyxiation, fear of dying, and growing fear (panic-like) during their breakdowns. Subjects with "nervous breakdown" and affective disorder had a greater sensation of anger and more tendency toward screaming and aggressive behavior such as breaking things during the breakdown (emotional anger). Finally, subjects with "nervous breakdown" and co-morbidity with another anxiety disorder had fewer "paniclike" or "emotional anger" symptoms. These findings suggest that: a) the widely used term "nervous breakdown" is a popular label for different patterns of loss of emotional control; b) the type of loss of emotional control is influenced by the associated psychiatric disorder; and c) the symptoms characteristics of the "nervous breakdown" can be useful clinical markers for associated psychiatric disorders. Future research is needed to determine whether the known Hispanic entity "ataque de nervios" is simply a popular description for different aspects of well-known psychiatric disorders, or if it reflects specific demographic, environmental, personality and/or clinical

Fast Breakdown as Coronal/Ionization Waves?

Science.gov (United States)

Krehbiel, P. R.; Petersen, D.; da Silva, C. L.

2017-12-01

Studies of high-power narrow bipolar events (NBEs) have shown they are produced by a newly-recognized breakdown process called fast positive breakdown (FPB, Rison et al., 2016, doi:10.1038/ncomms10721). The breakdown was inferred to be produced by a system of positive streamers that propagate at high speed ( ˜3-6 x 107 m/s) due to occurring in a localized region of strong electric field. The polarity of the breakdown was determined from broadband interferometer (INTF) observations of the propagation direction of its VHF radiation, which was downward into the main negative charge region of a normally-electrified storm. Subsequent INTF observations being conducted in at Kennedy Space Center in Florida have shown a much greater incidence of NBEs than in New Mexico. Among the larger dataset have been clear-cut instances of some NBEs being produced by upward breakdown that would be of negative polarity. The speed and behavior of the negative breakdown is the same as that of the fast positive, leading to it being termed fast negative breakdown (FNB). The similarity (not too mention its occurrence) is surprising, given the fact that negative streamers and breakdown develops much differently than that of positive breakdown. The question is how this happens. In this study, we compare fast breakdown characteristics to well-known streamer properties as inferred from laboratory experiments and theoretical analysis. Additionally, we begin to explore the possibility that both polarities of fast breakdown are produced by what may be called coronal or ionization waves, in which the enhanced electric field produced by streamer or coronal breakdown of either polarity propagates away from the advancing front at the speed of light into a medium that is in a metastable condition of being at the threshold of hydrometeor-mediated corona onset or other ionization processes. The wave would develop at a faster speed than the streamer breakdown that gives rise to it, and thus would be

A Model for the Onset of Vortex Breakdown

Science.gov (United States)

Mahesh, K.

1996-01-01

A large body of information exists on the breakdown of incompressible streamwise vortices. Less is known about vortex breakdown at high speeds. An interesting example of supersonic vortex breakdown is the breakdown induced by the interaction of vortices with shock waves. The flow in supersonic engine inlets and over high-speed delta wings constitute technologically important examples of this phenomenon, which is termed 'shock-induced vortex breakdown'. In this report, we propose a model to predict the onset of shock-induced vortex breakdown. The proposed model has no adjustable constants, and is compared to both experiment and computation. The model is then extended to consider two other problems: the breakdown of a free compressible vortex, and free incompressible vortex breakdown. The same breakdown criterion is used in all three problems to predict the onset of breakdown. Finally, a new breakdown map is proposed that allows the simultaneous comparison of data from flows ranging from incompressible breakdown to breakdown induced by a shock wave.

Lactobacillus sakei CRL1862 improves safety and protein hydrolysis in meat systems.

Science.gov (United States)

Castellano, P; Aristoy, M C; Sentandreu, M A; Vignolo, G; Toldrá, F

2012-12-01

The capacity of Lactobacillus sakei CRL1862 to prevent the growth of pathogens and its ability to degrade sarcoplasmic and myofibrillar proteins in pork meat systems was evaluated. In addition, basic safety aspects of Lact. sakei CRL1862 such as production of biogenic amines and antibiotic susceptibility were addressed. The bacteriocin-producing Lact. sakei CRL1862 showed respectively bactericide and bacteriostatic effect against Listeria monocytogenes and Staphylococcus aureus in beaker sausage assay during 9 days of storage at 22 °C. The hydrolytic effect of Lact. sakei CRL1862 on protein extracts was evaluated by SDS-PAGE and reverse phase HPLC. A more pronounced proteolysis was evidenced in inoculated sarcoplasmic proteins compared with myofibrillar extracts with the generation of predominantly hydrophilic peptides and increase of total free amino acids concentration. Lactobacillus sakei CRL1862 produced neither histamine nor tyrosine and exhibited no resistance to the antibiotics assayed. Lactobacillus sakei CRL1862 effectively controlled the growth of L. monocytogenes and Staph. aureus; moreover, it was able to hydrolyse pork meat extracts generating peptides and amino acids, which may improve hygienic and sensorial attributes of fermented meat products. The use of an integrated approach to evaluate the major traits of Lact. sakei CRL1862 showed it can be applied as an autochthonous functional starter in meat fermentation. © 2012 The Society for Applied Microbiology.

Voltage breakdown on niobium and copper surfaces

International Nuclear Information System (INIS)

Werner, G.R.; Padamsee, H.; Betzwieser, J.C.; Liu, Y.G.; Rubin, K.H.R.; Shipman, J.E.; Ying, L.T.

2003-01-01

Experiments have shown that voltage breakdown in superconducting niobium RF cavities is in many ways similar to voltage breakdown on niobium cathodes in DC voltage gaps; most striking are the distinctive starburst patterns and craters that mark the site of voltage breakdown in both superconducting cavities and DC vacuum gaps. Therefore, we can learn much about RF breakdown from simpler, faster DC experiments. We have direct evidence, in the form of before'' and ''after'' pictures, that breakdown events caused by high surface electric fields occur with high probability at contaminant particles on surfaces. Although the pre-breakdown behavior (field emission) seems to depend mostly on the contaminant particles present and little on the substrate, the breakdown event itself is greatly affected by the substrate-niobium, heavily oxidized niobium, electropolished copper, and diamond-machined copper cathodes lead to different kinds of breakdown events. By studying DC voltage breakdown we hope to learn more details about the processes involved in the transition from field emission to catastrophic arcing and the cratering of the surface; as well as learning how to prevent breakdown, we would like to learn how to cause breakdown, which could be important when ''processing'' cavities to reduce field emission. (author)

Effect of prolonged intravenous glucose and essential amino acid infusion on nitrogen balance, muscle protein degradation and ubiquitin-conjugating enzyme gene expression in calves

Directory of Open Access Journals (Sweden)

Scaife Jes R

2008-02-01

Full Text Available Abstract Background Intravenous infusions of glucose and amino acids increase both nitrogen balance and muscle accretion. We hypothesised that co-infusion of glucose (to stimulate insulin and essential amino acids (EAA would act additively to improve nitrogen balance by decreasing muscle protein degradation in association with alterations in muscle expression of components of the ubiquitin-proteasome proteolytic pathway. Methods We examined the effect of a 5 day intravenous infusions of saline, glucose, EAA and glucose + EAA, on urinary nitrogen excretion and muscle protein degradation. We carried out the study in 6 restrained calves since ruminants offer the advantage that muscle protein degradation can be assessed by excretion of 3 methyl-histidine and multiple muscle biopsies can be taken from the same animal. On the final day of infusion blood samples were taken for hormone and metabolite measurement and muscle biopsies for expression of ubiquitin, the 14-kDa E2 ubiquitin conjugating enzyme, and proteasome sub-units C2 and C8. Results On day 5 of glucose infusion, plasma glucose, insulin and IGF-1 concentrations were increased while urea nitrogen excretion and myofibrillar protein degradation was decreased. Co-infusion of glucose + EAA prevented the loss of urinary nitrogen observed with EAA infusions alone and enhanced the increase in plasma IGF-1 concentration but there was no synergistic effect of glucose + EAA on the decrease in myofibrillar protein degradation. Muscle mRNA expression of the ubiquitin conjugating enzyme, 14-kDa E2 and proteasome sub-unit C2 were significantly decreased, after glucose but not amino acid infusions, and there was no further response to the combined infusions of glucose + EAA. Conclusion Prolonged glucose infusion decreases myofibrillar protein degradation, prevents the excretion of infused EAA, and acts additively with EAA to increase plasma IGF-1 and improve net nitrogen balance. There was no evidence of

On dielectric breakdown statistics

International Nuclear Information System (INIS)

Tuncer, Enis; James, D Randy; Sauers, Isidor; Ellis, Alvin R; Pace, Marshall O

2006-01-01

In this paper, we investigate the dielectric breakdown data of some insulating materials and focus on the applicability of the two- and three-parameter Weibull distributions. A new distribution function is also proposed. In order to assess the model distribution's trustworthiness, we employ the Monte Carlo technique and, randomly selecting data-subsets from the whole dielectric breakdown data, determine whether the selected probability functions accurately describe the breakdown data. The utility and strength of the proposed expression are illustrated distinctly by the numerical procedure. The proposed expression is shown to be a valuable alternative to the Weibull ones

Three-dimensional supersonic vortex breakdown

Science.gov (United States)

Kandil, Osama A.; Kandil, Hamdy A.; Liu, C. H.

1993-01-01

Three-dimensional supersonic vortex-breakdown problems in bound and unbound domains are solved. The solutions are obtained using the time-accurate integration of the unsteady, compressible, full Navier-Stokes (NS) equations. The computational scheme is an implicit, upwind, flux-difference splitting, finite-volume scheme. Two vortex-breakdown applications are considered in the present paper. The first is for a supersonic swirling jet which is issued from a nozzle into a supersonic uniform flow at a lower Mach number than that of the swirling jet. The second is for a supersonic swirling flow in a configured circular duct. In the first application, an extensive study of the effects of grid fineness, shape and grid-point distribution on the vortex breakdown is presented. Four grids are used in this study and they show a substantial dependence of the breakdown bubble and shock wave on the grid used. In the second application, the bubble-type and helix-type vortex breakdown have been captured.

Muscle and liver glycogen, protein, and triglyceride in the rat

DEFF Research Database (Denmark)

Richter, Erik; Sonne, Bente; Joensen Mikines, Kari

1984-01-01

in skeletal muscle was accompanied by increased breakdown of triglyceride and/or protein. Thus, the effect of exhausting swimming and of running on concentrations of glycogen, protein, and triglyceride in skeletal muscle and liver were studied in rats with and without deficiencies of the sympatho......-adrenal system. In control rats, both swimming and running decreased the concentration of glycogen in fast-twitch red and slow-twitch red muscle whereas concentrations of protein and triglyceride did not decrease. In the liver, swimming depleted glycogen stores but protein and triglyceride concentrations did...... not decrease. In exercising rats, muscle glycogen breakdown was impaired by adrenodemedullation and restored by infusion of epinephrine. However, impaired glycogen breakdown during exercise was not accompanied by a significant net breakdown of protein or triglyceride. Surgical sympathectomy of the muscles did...

Shock/vortex interaction and vortex-breakdown modes

Science.gov (United States)

Kandil, Osama A.; Kandil, H. A.; Liu, C. H.

1992-01-01

Computational simulation and study of shock/vortex interaction and vortex-breakdown modes are considered for bound (internal) and unbound (external) flow domains. The problem is formulated using the unsteady, compressible, full Navier-Stokes (NS) equations which are solved using an implicit, flux-difference splitting, finite-volume scheme. For the bound flow domain, a supersonic swirling flow is considered in a configured circular duct and the problem is solved for quasi-axisymmetric and three-dimensional flows. For the unbound domain, a supersonic swirling flow issued from a nozzle into a uniform supersonic flow of lower Mach number is considered for quasi-axisymmetric and three-dimensional flows. The results show several modes of breakdown; e.g., no-breakdown, transient single-bubble breakdown, transient multi-bubble breakdown, periodic multi-bubble multi-frequency breakdown and helical breakdown.

Breakdown properties of irradiated MOS capacitors

International Nuclear Information System (INIS)

Paccagnella, A.; Candelori, A.; Pellizzer, F.; Fuochi, P.G.; Lavale, M.

1996-01-01

The authors have studied the effects of ionizing and non-ionizing radiation on the breakdown properties of different types of MOS capacitors, with thick (200 nm) and thin (down to 8 nm) oxides. In general, no large variations of the average breakdown field, time-to-breakdown at constant voltage, or charge-to-breakdown at constant voltage, or charge-to-breakdown values have been observed after high dose irradiation (20 Mrad(Si) 9 MeV electrons on thin and thick oxides, 17(Si) Mrad Co 60 gamma and 10 14 neutrons/cm 2 only on thick oxides). However, some modifications of the cumulative failure distributions have been observed in few of the oxides tested

Breakdown characteristics of xenon HID Lamps

Science.gov (United States)

Babaeva, Natalia; Sato, Ayumu; Brates, Nanu; Noro, Koji; Kushner, Mark

2009-10-01

The breakdown characteristics of mercury free xenon high intensity discharge (HID) lamps exhibit a large statistical time lag often having a large scatter in breakdown voltages. In this paper, we report on results from a computational investigation of the processes which determine the ignition voltages for positive and negative pulses in commercial HID lamps having fill pressures of up to 20 atm. Steep voltage rise results in higher avalanche electron densities and earlier breakdown times. Circuit characteristics also play a role. Large ballast resistors may limit current to the degree that breakdown is quenched. The breakdown voltage critically depends on cathode charge injection by electric field emission (or other mechanisms) which in large part controls the statistical time lag for breakdown. For symmetric lamps, ionization waves (IWs) simultaneously develop from the bottom and top electrodes. Breakdown typically occurs when the top and bottom IWs converge. Condensed salt layers having small conductivities on the inner walls of HID lamps and on the electrodes can influence the ignition behavior. With these layers, IWs tend to propagate along the inner wall and exhibit a different structure depending on the polarity.

Skin breakdown in acute care pediatrics.

Science.gov (United States)

Suddaby, Elizabeth C; Barnett, Scott D; Facteau, Lorna

2006-04-01

The purpose of this study was to develop a simple, single-page measurement tool that evaluates risk of skin breakdown in the peadiatric population and apply it to the acutely hospitalized child. Data were collected over a 15-month period from 347 patients on four in-patient units (PICU, medical-surgical, oncology, and adolescents) on skin breakdown using the AHCPR staging guidelines and compared to the total score on the Starkid SkinScale in order to determine its ability to predict skin breakdown. The inter-rater reliability of the Starkid Skin Scale was r2 = 0.85 with an internal reliablity of 0.71. The sensitivity of the total score was low (17.5%) but highly specific (98.5%). The prevalence of skin breakdown in the acutely hospitalized child was 23%, the majority (77.5%) occurring as erythema of the skin. Buttocks, perineum, and occiput were the most common locations of breakdown. Occiput breakdown was more common in critically ill (PICU) patients while diaper dermatitis was more common in the general medical-surgical population.

A high protein diet upregulated whole-body protein turnover during energy deficit

Science.gov (United States)

The effects of higher protein diets and sustained energy deficit (ED) on whole-body protein turnover (WBPTO) are not well described. This study examined whether dietary protein level influences whole-body protein breakdown (Ra), non-oxidative leucine disposal (NOLD), and oxidation (Ox) during ED. ...

Breakdown concepts for contingency tables

NARCIS (Netherlands)

Kuhnt, S.

2010-01-01

Loglinear Poisson models are commonly used to analyse contingency tables. So far, robustness of parameter estimators as well as outlier detection have rarely been treated in this context. We start with finite-sample breakdown points. We yield that the breakdown point of mean value estimators

High gradient RF breakdown study

International Nuclear Information System (INIS)

Laurent, L.; Luhmann, N.C. Jr.; Scheitrum, G.; Hanna, S.; Pearson, C.; Phillips, R.

1998-01-01

Stanford Linear Accelerator Center and UC Davis have been investigating high gradient RF breakdown and its effects on pulse shortening in high energy microwave devices. RF breakdown is a critical issue in the development of high power microwave sources and next generation linear accelerators since it limits the output power of microwave sources and the accelerating gradient of linacs. The motivation of this research is to find methods to increase the breakdown threshold level in X-band structures by reducing dark current. Emphasis is focused on improved materials, surface finish, and cleanliness. The test platform for this research is a traveling wave resonant ring. A 30 MW klystron is employed to provide up to 300 MW of traveling wave power in the ring to trigger breakdown in the cavity. Five TM 01 cavities have previously been tested, each with a different combination of surface polish and/or coating. The onset of breakdown was extended up to 250 MV/m with a TiN surface finish, as compared to 210 MV/m for uncoated OFE copper. Although the TiN coating was helpful in depressing the field emission, the lowest dark current was obtained with a 1 microinch surface finish, single-point diamond-turned cavity

Humidity effects on wire insulation breakdown strength.

Energy Technology Data Exchange (ETDEWEB)

Appelhans, Leah

2013-08-01

Methods for the testing of the dielectric breakdown strength of insulation on metal wires under variable humidity conditions were developed. Two methods, an ASTM method and the twisted pair method, were compared to determine if the twisted pair method could be used for determination of breakdown strength under variable humidity conditions. It was concluded that, although there were small differences in outcomes between the two testing methods, the non-standard method (twisted pair) would be appropriate to use for further testing of the effects of humidity on breakdown performance. The dielectric breakdown strength of 34G copper wire insulated with double layer Poly-Thermaleze/Polyamide-imide insulation was measured using the twisted pair method under a variety of relative humidity (RH) conditions and exposure times. Humidity at 50% RH and below was not found to affect the dielectric breakdown strength. At 80% RH the dielectric breakdown strength was significantly diminished. No effect for exposure time up to 140 hours was observed at 50 or 80%RH.

Multiple helical modes of vortex breakdown

DEFF Research Database (Denmark)

Sørensen, Jens Nørkær; Naumov, I. V.; Okulov, Valery

2011-01-01

Experimental observations of vortex breakdown in a rotating lid-driven cavity are presented. The results show that vortex breakdown for cavities with high aspect ratios is associated with the appearance of stable helical vortex multiplets. By using results from stability theory generalizing Kelvi......’s problem on vortex polygon stability, and systematically exploring the cavity flow, we succeeded in identifying two new stable vortex breakdown states consisting of triple and quadruple helical multiplets....

A computational study of the topology of vortex breakdown

Science.gov (United States)

Spall, Robert E.; Gatski, Thomas B.

1991-01-01

A fully three-dimensional numerical simulation of vortex breakdown using the unsteady, incompressible Navier-Stokes equations has been performed. Solutions to four distinct types of breakdown are identified and compared with experimental results. The computed solutions include weak helical, double helix, spiral, and bubble-type breakdowns. The topological structure of the various breakdowns as well as their interrelationship are studied. The data reveal that the asymmetric modes of breakdown may be subject to additional breakdowns as the vortex core evolves in the streamwise direction. The solutions also show that the freestream axial velocity distribution has a significant effect on the position and type of vortex breakdown.

Discharge breakdown in the EXTRAP configuration

International Nuclear Information System (INIS)

Drake, J.R.

1982-02-01

The breakdown of a discharge in a linear EXTRAP configuration has been studied experimentally. In this configuration the breakdown occurs along the zero B-field line, which is the axis of the linear octupole magnetic field, between the anode and cathode which constitute the ends of the linear device. Breakdown could be described by a modified Townsend criterion which included additional electron losses due to the presence of the B-field transverse to the discharge. (author)

Electrode breakdown potentials in MHD plasmas

International Nuclear Information System (INIS)

Sodha, M.S.; Raju, G.V.R.; Kumar, A.S.; Gupta, Bhumesh

1988-01-01

Electrode breakdown potentials and current densities have been calculated for both the thermionically electron emitting and non-emitting cathodes. Calculated values have been compared with the available experimental results. It is found that the cathode potential drop for the breakdown is almost unaffected by the emission. However, both the total potential difference between the anode and the cathode and the current density at the breakdown are higher for electron-emitting cathodes than for non-emitting cathodes. (author)

No additional effect of different types of physical activity on 10-hour muscle protein synthesis in elderly men on a controlled energy- and protein-sufficient diet

DEFF Research Database (Denmark)

Bulow, Jacob; Agergaard, Jakob; Kjær, Michael

2016-01-01

protein synthesis (MPS) are less investigated. The aim of this study was to determine the effects of daily physical activities upon MPS in elderly individuals. Methods: A total of 24 elderly men (70 +/- 1 year) were recruited and randomly assigned: inactivity in form of bed-rest (IA), daily physical......-hour myofibrillar protein fractional synthesis rates (FSR), and typical prerequisites for calculating FSR were fulfilled. Physical activities were monitored, and venous blood and muscle biopsies collected. Results: Physical activity was highest in the DA compared to both the IA and RE groups. Nutrient...... activities (DA), or heavy resistance exercise (RE). All groups undertook a normal eating routine containing carbohydrates (52 E%), fat (32 E%), and protein (16 E%). Ingestion of labeled milk protein ([1-C-13] leucine-labeled whey and caseinate) served to maintain tracer enrichment for determination of 10...

The Multistability of Technological Breakdowns in Education

DEFF Research Database (Denmark)

Andersen, Bjarke Lindsø; Tafdrup, Oliver Alexander

2017-01-01

Introduction Everyone who is involved with modern technological artefacts such as computers, software and tablets has experienced situations where the artefacts suddenly cease to function properly. This is commonly known as a technological breakdown. Within education and the praxis of teaching...... technological breakdowns become a more and more ubiquitous phenomenon due to the rapid increase of technological artefacts utilized for educational purposes (Riis, 2012). The breakdowns impact the educational practice with consequences ranging from creating small obstacles to rendering it impossible to conduct...... successful teaching. Thus, knowing how to cope with technological breakdowns is a pivotal part of being a technological literate....

Investigations of dc breakdown fields

CERN Document Server

Ramsvik, Trond; Reginelli, Alessandra; Taborelli, Mauro

2006-01-01

The need for high accelerating gradients for the future 30 GHz multi-TeV e+e- Compact Linear Collider (CLIC) at CERN has triggered a comprehensive study of DC breakdown fields of metals in UHV. The study shows that molybdenum (Mo), tungsten (W), titanium (Ti) and TiVAl reach high breakdown fields, and are thus good candidates for the iris material of CLIC structures. A significant decrease in the saturated breakdown field (Esat) is observed for molybdenum and tungsten when exposed to air. Specifically, at air pressures of 10-5 mbar, the decrease in Esat is found to be 50% and 30% for molybdenum and tungsten, respectively. In addition, a 30% decrease is found when molybdenum is conditioned with a CO pressure of ~1-10-5 mbar. Surface analysis measurements and breakdown conditioning in O2 ambience imply that the origin of the decrease in Esat is closely linked to oxide formation on the cathode surface. "Ex-situ" treatments by ion bombardment of molybdenum effectively reduce the oxide layers, and improve the brea...

Planned waveguide electric field breakdown studies

International Nuclear Information System (INIS)

Wang Faya; Li Zenghai

2012-01-01

This paper presents an experimental setup for X-band rf breakdown studies. The setup is composed of a section of WR90 waveguide with a tapered pin located at the middle of the waveguide E-plane. Another pin is used to rf match the waveguide so it operates in a travelling wave mode. By adjusting the penetration depth of the tapered pin, different surface electric field enhancements can be obtained. The setup will be used to study the rf breakdown rate dependence on power flow in the waveguide for a constant maximum surface electric field on the pin. Two groups of pins have been designed. The Q of one group is different and very low. The other has a similar Q. With the test of the two groups of pins, we should be able to discern how the net power flow and Q affect the breakdown. Furthermore, we will apply an electron beam treatment to the pins to study its effect on breakdown. Overall, these experiments should be very helpful in understanding rf breakdown phenomena and could significantly benefit the design of high gradient accelerator structures.

Experiments concerning the theories of vortex breakdown

Science.gov (United States)

Panton, Ronald L.; Stifle, Kirk E.

1991-01-01

An experimental project was undertaken to investigate the character of vortex breakdown with particular regard to the stagnation and wave guide theories of vortex breakdown. Three different wings were used to produce a trailing vortex which convected downstream without undergoing breakdown. Disturbances were then introduced onto the vortex using a moving wire to 'cut' the vortex. The development of upstream and downstream propagating disturbance waves was observed and the propagation velocities measured. A downstream traveling wave was observed to produce a structure similar in appearance to a vortex breakdown. An upstream traveling wave produced a moving turbulent region. The upstream disturbance moved into an axial velocity profile that had a wake-like defect while the downstream moving vortex breakdown moved against a jet-like overshoot. The longitudinal and swirl velocity profiles were documented by LDV measurement. Wave velocities, swirl angles, and swirl parameters are reported.

The Development of Breakdown in Transformer Oil

Directory of Open Access Journals (Sweden)

Jozef Kudelcik

2007-01-01

Full Text Available The conditions under which breakdown of composite liquid - solid insulation can be occurred, e.g. in transformer, play an important role in designing of such insulation. The initial state of breakdown development is explained based on development of streamers in cavitations. The whole breakdown development in transformer oil is represented by RLC circuit and it depends on the parameters of outer circuit.

BAG3 Directly Interacts with Mutated alphaB-Crystallin to Suppress Its Aggregation and Toxicity

NARCIS (Netherlands)

Hishiya, Akinori; Salman, Mortada Najem; Carra, Serena; Kampinga, Harm H.; Takayama, Shinichi

2011-01-01

A homozygous disruption or genetic mutation of the bag3 gene causes progressive myofibrillar myopathy in mouse and human skeletal and cardiac muscle disorder while mutations in the small heat shock protein aB-crystallin gene ( CRYAB) are reported to be responsible for myofibrillar myopathy. Here, we

Lack of functional benefit with glutamine versus placebo in Duchenne muscular dystrophy: a randomized crossover trial.

Directory of Open Access Journals (Sweden)

Elise Mok

Full Text Available Oral glutamine decreases whole body protein breakdown in Duchenne muscular dystrophy (DMD. We evaluated the functional benefit of 4 months oral glutamine in DMD.30 ambulant DMD boys were included in this double-blind, randomized crossover trial with 2 intervention periods: glutamine (0.5 g/kg/d and placebo, 4 months each, separated by a 1-month wash-out, at 3 outpatient clinical investigation centers in France. Functional benefit was tested by comparing glutamine versus placebo on change in walking speed at 4 months. Secondary outcome measures were: 2-minute walk test, work, power, muscle mass (urinary creatinine, markers of myofibrillar protein breakdown (urinary 3-methyl-histidine/creatinine, serum creatine phospho-kinase, body composition (fat free mass, fat mass percentage, safety and oral nutrient intake. There was no improvement in the primary end point (walking speed or in secondary measures of muscle function (2-minute walk test, work, power in the glutamine group compared with placebo. However, subjects receiving glutamine or placebo showed no deterioration in functional measures over the course of the 9-month trial. No differences in muscle mass, markers of protein breakdown or serum creatine phosho-kinase were observed, except for a blunted increase in fat free mass in the glutamine group which led to a greater increase in fat mass percentage. Glutamine was safe and well-tolerated.This trial did not identify additional benefit of 4 months oral glutamine over placebo on muscle mass or function in ambulatory DMD boys. Although apparently safe, current data cannot support routine supplementation in this population as a whole, until further research proves otherwise.(ClinicalTrials.gov NCT00296621.

Formation of vortex breakdown in conical–cylindrical cavities

International Nuclear Information System (INIS)

Martins, Diego Alves de Moro; Souza, Francisco José de; Salvo, Ricardo de Vasconcelos

2014-01-01

Highlights: • Rotating flows in conical–cylindrical cavities were simulated via an in-house code using unstructured meshes. • The vortex breakdown phenomenon was verified in the geometries analyzed. • The influence of Stewartson and Bödewadt layers was observed in the vortex breakdown formation. • A curve of stability and number of breakdowns was obtained as a function of Reynolds number. • Spiral vortex breakdown was observed in some situations. - Abstract: Numerical simulations in confined rotating flows were performed in this work, in order to verify and characterize the formation of the vortex breakdown phenomenon. Cylindrical and conical–cylindrical geometries, both closed, were used in the simulations. The rotating flow is induced by the bottom wall, which rotates at constant angular velocity. Firstly the numerical results were compared to experimental results available in references, with the purpose to verify the capacity of the computational code to predict the vortex breakdown phenomenon. Further, several simulations varying the parameters which govern the characteristics of the flows analyzed in this work, i.e., the Reynolds number and the aspect ratio, were performed. In these simulations, the limits for the transitional regime and the vortex breakdown formation were verified. Steady and transient cases, with and without turbulence modeling, were simulated. In general, some aspects of the process of vortex breakdown in conical–cylindrical geometries were observed to be different from that in cylinders

Analyzing randomly occurring voltage breakdowns

International Nuclear Information System (INIS)

Wiltshire, C.W.

1977-01-01

During acceptance testing of high-vacuum neutron tubes, 40% of the tubes failed after experiencing high-voltage breakdowns during the aging process. Use of a digitizer in place of an oscilloscope revealed two types of breakdowns, only one of which affected acceptance testing. This information allowed redesign of the aging sequence to prevent tube damage and improve yield and quality of the final product

NSP-Dependent Simple Nitrile Formation Dominates upon Breakdown of Major Aliphatic Glucosinolates in Roots, Seeds, and Seedlings of Arabidopsis thaliana Columbia-0.

Science.gov (United States)

Wittstock, Ute; Meier, Kathrin; Dörr, Friederike; Ravindran, Beena M

2016-01-01

One of the best-studied plant defense systems, the glucosinolate-myrosinase system of the Brassicales, is composed of thioglucosides known as glucosinolates and their hydrolytic enzymes, the myrosinases. Tissue disruption brings these components together, and bioactive products are formed as a consequence of myrosinase-catalyzed glucosinolate hydrolysis. Among these products, isothiocyanates have attracted most interest as chemical plant defenses against herbivores and pathogens and health-promoting compounds in the human diet. Previous research has identified specifier proteins whose presence results in the formation of alternative product types, e.g., nitriles, at the expense of isothiocyanates. The biological roles of specifier proteins and alternative breakdown products are poorly understood. Here, we assessed glucosinolate breakdown product profiles obtained upon maceration of roots, seedlings and seeds of Arabidopsis thaliana Columbia-0. We identified simple nitriles as the predominant breakdown products of the major endogenous aliphatic glucosinolates in root, seed, and seedling homogenates. In agreement with this finding, genes encoding nitrile-specifier proteins (NSPs) are expressed in roots, seeds, and seedlings. Analysis of glucosinolate breakdown in mutants with T-DNA insertions in any of the five NSP genes demonstrated, that simple nitrile formation upon tissue disruption depended almost entirely on NSP2 in seeds and mainly on NSP1 in seedlings. In roots, about 70-80% of the nitrile-forming activity was due to NSP1 and NSP3 . Thus, glucosinolate breakdown product profiles are organ-specifically regulated in A. thaliana Col-0, and high proportions of simple nitriles are formed in some parts of the plant. This should be considered in future studies on biological roles of the glucosinolate-myrosinase system.

NSP-dependent simple nitrile formation dominates upon breakdown of major aliphatic glucosinolates in roots, seeds, and seedlings of Arabidopsis thaliana Columbia-0

Directory of Open Access Journals (Sweden)

Ute Wittstock

2016-12-01

Full Text Available One of the best-studied plant defense systems, the glucosinolate-myrosinase system of the Brassicales, is composed of thioglucosides known as glucosinolates and their hydrolytic enzymes, the myrosinases. Tissue disruption brings these components together, and bioactive products are formed as a consequence of myrosinase-catalyzed glucosinolate hydrolysis. Among these products, isothiocyanates have attracted most interest as chemical plant defenses against herbivores and pathogens and health-promoting compounds in the human diet. Previous research has identified specifier proteins whose presence results in the formation of alternative product types, e.g. nitriles, at the expense of isothiocyanates. The biological roles of specifier proteins and alternative breakdown products are poorly understood. Here, we assessed glucosinolate breakdown product profiles obtained upon maceration of roots, seedlings and seeds of Arabidopsis thaliana Columbia-0. We identified simple nitriles as the predominant breakdown products of the major endogenous aliphatic glucosinolates in root, seed, and seedling homogenates. In agreement with this finding, genes encoding nitrile-specifier proteins (NSPs are expressed in roots, seeds, and seedlings. Analysis of glucosinolate breakdown in mutants with T-DNA insertions in any of the five NSP genes demonstrated, that simple nitrile formation upon tissue disruption depended almost entirely on NSP2 in seeds and mainly on NSP1 in seedlings. In roots, about 70-80 % of the nitrile-forming activity was due to NSP1 and NSP3. Thus, glucosinolate breakdown product profiles are organ-specifically regulated in A. thaliana Col 0, and high proportions of simple nitriles are formed in some parts of the plant. This should be considered in future studies on biological roles of the glucosinolate-myrosinase system.

Methodical investigation of the protein metabolism and of the bioenergetics of the protein retention in growing animals. 2

International Nuclear Information System (INIS)

Voelker, T.; Krawielitzki, K.; Klein, M.; Keller, J.

1983-01-01

The amino acid composition of the proteins in selected body fractions of chickens and the 15 N -excess of amino acids isolated from them resulting from a feeding experiment with long-term 15 NH 4 -acetate labelling were determined. The amino acid spectra of feathers, breast and leg muscles are characterized by differences in the content of individual amino acids specific for the organs, the composition of the proteins, however, is independent of the protein content of the ration and the age of the animals. The sarcoplasmatic and myofibrillar proteins also have typical amino acid patterns, which-with the exception of the histidine content-are neither influenced by the extraction of the proteins from the breast or leg muscles nor by the energy level of the feeding or the age of the animals. There are no significant differences in the metabolization of the main protein fraction of the breast and leg muscles. The oral supply of 15 N-ammonium acetate to broilers predominantly labels the non-essential amino acids so that the derived kinetic data chiefly represent the metabolism of the non-essential amino acids. (author)

Impulse breakdown of liquids

CERN Document Server

Ushakov, Vasily Y

2007-01-01

The book describes the main physical processes and phenomena in pulsed electric breakdown. The knowledge and the control of the electric breakdown of liquids is important not only for the insulation inside power systems but it is also used for the creation and information of high voltage and high current pulses. Such high-voltage micro- and nanosecond pulses find wide application in experimental physics, electro discharge technology, physics of dielectrics, radar detection and ranging, high-speed photography. The nature of charge carriers, mechanism of formation and evolution of the gas phase,

Pressurized-helium breakdown at very low temperatures

Energy Technology Data Exchange (ETDEWEB)

Metas, R J

1972-06-01

An investigation of the electrical-breakdown behavior of helium at very low temperatures has been carried out to assist the design and development of superconducting power cables. At very high densities, both liquid and gaseous helium showed an enhancement in electric strength when pressurized to a few atmospheres; conditioned values of breakdown fields then varied between 30 and 45 MV/m. Breakdown processes occurring over a wide range of helium densities are discussed. 24 references.

Comparative Studies of High-Gradient Rf and Dc Breakdowns

CERN Document Server

Kovermann, Jan Wilhelm; Wuensch, Walter

2010-01-01

The CLIC project is based on normal-conducting high-gradient accelerating structures with an average accelerating gradient of 100 MV/m. The maximum achievable gradient in these structures is limited by the breakdown phenomenon. The physics of breakdowns is not yet fully understood quantitatively. A full knowledge could have strong impact on the design, material choice and construction of rf structures. Therefore, understanding breakdowns has great importance to reaching a gradient of 100MV/m with an acceptable breakdown probability. This thesis addresses the physics underlying the breakdown effect, focusing on a comparison of breakdowns in rf structures and in a dc spark setup. The dc system is simpler, easier to benchmark against simulations, with a faster turnaround time, but the relationship to rf breakdown must be established. To do so, an experimental approach based on optical diagnostics and electrical measurements methods was made. Following an introduction into the CLIC project, a general theoretical ...

Numerical Borehole Breakdown Investigations using XFEM

Science.gov (United States)

Beckhuis, Sven; Leonhart, Dirk; Meschke, Günther

2016-04-01

During pressurization of a wellbore a typical downhole pressure record shows the following regimes: first the applied wellbore pressure balances the reservoir pressure, then after the compressive circumferential hole stresses are overcome, tensile stresses are induced on the inside surface of the hole. When the magnitude of these stresses reach the tensile failure stress of the surrounding rock medium, a fracture is initiated and propagates into the reservoir. [1] In standard theories this pressure, the so called breakdown pressure, is the peak pressure in the down-hole pressure record. However experimental investigations [2] show that the breakdown did not occur even if a fracture was initiated at the borehole wall. Drilling muds had the tendency to seal and stabilize fractures and prevent fracture propagation. Also fracture mechanics analysis of breakdown process in mini-frac or leak off tests [3] show that the breakdown pressure could be either equal or larger than the fracture initiation pressure. In order to gain a deeper understanding of the breakdown process in reservoir rock, numerical investigations using the extended finite element method (XFEM) for hydraulic fracturing of porous materials [4] are discussed. The reservoir rock is assumed to be pre-fractured. During pressurization of the borehole, the injection pressure, the pressure distribution and the position of the highest flux along the fracture for different fracturing fluid viscosities are recorded and the influence of the aforementioned values on the stability of fracture propagation is discussed. [1] YEW, C. H. (1997), "Mechanics of Hydraulic Fracturing", Gulf Publishing Company [2] MORITA, N.; BLACK, A. D.; FUH, G.-F. (1996), "Borehole Breakdown Pressure with Drilling Fluids". International Journal of Rock Mechanics and Mining Sciences 33, pp. 39-51 [3] DETOURNAY, E.; CARBONELL, R. (1996), "Fracture Mechanics Analysis of the Breakdown Process in Minifrac or Leakoff Test", Society of Petroleum

Gauge theories as theories of spontaneous breakdown

International Nuclear Information System (INIS)

Ivanov, E.A.; Ogievetsky, V.I.

1976-01-01

Any gauge theory is proved to arise from spontaneous breakdown of symmetry under certain infinite parameter group, the corresponding gauge field being the Goldstone field by which this breakdown is accompanied

Breakdown coefficients and scaling properties of rain fields

Directory of Open Access Journals (Sweden)

D. Harris

1998-01-01

Full Text Available The theory of scale similarity and breakdown coefficients is applied here to intermittent rainfall data consisting of time series and spatial rain fields. The probability distributions (pdf of the logarithm of the breakdown coefficients are the principal descriptor used. Rain fields are distinguished as being either multiscaling or multiaffine depending on whether the pdfs of breakdown coefficients are scale similar or scale dependent, respectively. Parameter  estimation techniques are developed which are applicable to both multiscaling and multiaffine fields. The scale parameter (width, σ, of the pdfs of the log-breakdown coefficients is a measure of the intermittency of a field. For multiaffine fields, this scale parameter is found to increase with scale in a power-law fashion consistent with a bounded-cascade picture of rainfall modelling. The resulting power-law exponent, H, is indicative of the smoothness of the field. Some details of breakdown coefficient analysis are addressed and a theoretical link between this analysis and moment scaling analysis is also presented. Breakdown coefficient properties of cascades are also investigated in the context of parameter estimation for modelling purposes.

Electrical breakdown phenomena of dielectric elastomers

DEFF Research Database (Denmark)

Mateiu, Ramona Valentina; Yu, Liyun; Skov, Anne Ladegaard

2017-01-01

Silicone elastomers have been heavily investigated as candidates for dielectric elastomers and are as such almost ideal candidates with their inherent softness and compliance but they suffer from low dielectric permittivity. This shortcoming has been sought optimized by many means during recent...... years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we investigate the electrical breakdown phenomena of various types of permittivity-enhanced silicone elastomers. Two types...... of silicone elastomers are investigated and different types of breakdown are discussed. Furthermore the use of voltage stabilizers in silicone-based dielectric elastomers is investigated and discussed....

Sample preconcentration utilizing nanofractures generated by junction gap breakdown assisted by self-assembled monolayer of gold nanoparticles.

Directory of Open Access Journals (Sweden)

Chun-Ping Jen

Full Text Available The preconcentration of proteins with low concentrations can be used to increase the sensitivity and accuracy of detection. A nonlinear electrokinetic flow is induced in a nanofluidic channel due to the overlap of electrical double layers, resulting in the fast accumulation of proteins, referred to as the exclusion-enrichment effect. The proposed chip for protein preconcentration was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. This study extends our previous paper, in which gold nanoparticles were manually deposited onto the surface of a protein preconcentrator. In the present work, nanofractures were formed by utilizing the self-assembly of gold-nanoparticle-assisted electric breakdown. This reliable method for nanofracture formation, involving self-assembled monolayers of nanoparticles at the junction gap between microchannels, also decreases the required electric breakdown voltage. The experimental results reveal that a high concentration factor of 1.5×10(4 for a protein sample with an extremely low concentration of 1 nM was achieved in 30 min by using the proposed chip, which is faster than our previously proposed chip at the same conditions. Moreover, an immunoassay of bovine serum albumin (BSA and anti-BSA was carried out to demonstrate the applicability of the proposed chip.

Effects of gamma irradiation on physicochemical properties of heat-induced gel prepared with chicken salt-soluble proteins

International Nuclear Information System (INIS)

Choi, Yun-Sang; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Jeong, Tae-Jun; Seo, Kwang-Wook; Kim, Young-Boong; Kim, Cheon-Jei

2015-01-01

The technological effects of gamma irradiation (0, 3, 7, and 10 kGy) on chicken salt-soluble meat proteins in a model system were investigated. There were no significant differences in protein, fat, and ash content, and sarcoplasmic protein solubility among all samples. The samples with increasing gamma irradiation levels had higher pH, lightness, yellowness, and apparent viscosity, whereas moisture content, water holding capacity, redness, myofibrillar protein solubility, total protein solubility, hardness, springiness, cohesiveness, gumminess, and chewiness were the highest in the unirradiated control. The result from meat products using gamma irradiation was intended to provide a basic resource processing technology. - Highlights: • The effect of gamma irradiation on salt-soluble meat proteins was investigated. • Gelling properties of salt-soluble protein affected by gamma irradiation. • Gamma irradiation of meat products provides a basic resource processing technology

A computational study of the taxonomy of vortex breakdown

Science.gov (United States)

Spall, Robert E.; Gatski, Thomas B.

1990-01-01

The results of a fully three-dimensional numerical simulation of vortex breakdown using the unsteady, incompressible Navier-Stokes equations are presented. The solutions show that the freestream axial velocity distribution has a significant effect on the position and type of vortex breakdown. Common features between bubble-type and spiral-type breakdown are identified and the role of flow stagnation and the critical state are discussed as complimentary ideas describing the initiation of breakdown.

A Combined Electro-Thermal Breakdown Model for Oil-Impregnated Paper

Directory of Open Access Journals (Sweden)

Meng Huang

2017-12-01

Full Text Available The breakdown property of oil-impregnated paper is a key factor for converter transformer design and operation, but it is not well understood. In this paper, breakdown voltages of oil-impregnated paper were measured at different temperatures. The results showed that with the increase of temperature, electrical, electro-thermal and thermal breakdown occurred successively. An electro-thermal breakdown model was proposed based on the heat equilibrium and space charge transport, and negative differential mobility was introduced to the model. It was shown that carrier mobility determined whether it was electrical or thermal breakdown, and the model can effectively explain the temperature-dependent breakdown.

A kinetic model to simulate the effect of cooking time-temperature on the gastric digestion of meat

OpenAIRE

Kondjoyan, Alain; Daudin, Jean-Dominique; Portanguen, Stéphane; Aubry, Laurent; Sante-Lhoutellier, Veronique

2014-01-01

A kinetic model was developed to predict the effect of cooking time and temperature on the digestibility of myofibrillar proteins. The predictions were confronted to the measurement of the in vitro digestibility of myofibrillar proteins coming from either slices of beef meat heated in water bath or from a piece of meat roasted in a domestic oven. The model was able to simulate the in vitro measurements for the meat pieces of different sizes cooked under different condi...

Stress-induced breakdown during galvanostatic anodising of zirconium

International Nuclear Information System (INIS)

Van Overmeere, Q.; Proost, J.

2010-01-01

Although internal stress is frequently being suggested as a plausible reason for oxide breakdown during valve metal anodising, no direct quantitative evidence has been made available yet. In this work, we anodized sputtered zirconium thin films galvanostatically at room temperature in sulphuric acid until breakdown was observed, and simultaneously measured the internal stress evolution in the oxide in situ, using a high-resolution curvature setup. It was found that the higher the magnitude of the observed internal compressive stress in the oxide, the smaller the oxide thickness at which breakdown occurred. The moment of breakdown was identified from a slope change in the cell voltage evolution, indicative for a decrease in anodising efficiency. The latter presumably occurs as a result of oxygen evolution, initiated by the relative increase of the cubic or tetragonal zirconia phase content relative to the monoclinic one. This was evidenced in turn by comparing electron diffractograms, taken in a transmission electron microscope, before and after breakdown. The critical role of internal stress on oxide breakdown during zirconium anodising can therefore be associated with its promoting effect on the densifying phase transformation of monoclinic oxide.

Obstacle-induced spiral vortex breakdown

OpenAIRE

Pasche, Simon; Gallaire, François; Dreyer, Matthieu; Farhat, Mohamed

2014-01-01

An experimental investigation on vortex breakdown dynamics is performed. An adverse pressure gradient is created along the axis of a wing-tip vortex by introducing a sphere downstream of an elliptical hydrofoil. The instrumentation involves high-speed visualizations with air bubbles used as tracers and 2D Laser Doppler Velocimeter (LDV). Two key parameters are identified and varied to control the onset of vortex breakdown: the swirl number, defined as the maximum azimuthal velocity divided by...

Vortex breakdown incipience: Theoretical considerations

Science.gov (United States)

Berger, Stanley A.; Erlebacher, Gordon

1992-01-01

The sensitivity of the onset and the location of vortex breakdowns in concentrated vortex cores, and the pronounced tendency of the breakdowns to migrate upstream have been characteristic observations of experimental investigations; they have also been features of numerical simulations and led to questions about the validity of these simulations. This behavior seems to be inconsistent with the strong time-like axial evolution of the flow, as expressed explicitly, for example, by the quasi-cylindrical approximate equations for this flow. An order-of-magnitude analysis of the equations of motion near breakdown leads to a modified set of governing equations, analysis of which demonstrates that the interplay between radial inertial, pressure, and viscous forces gives an elliptic character to these concentrated swirling flows. Analytical, asymptotic, and numerical solutions of a simplified non-linear equation are presented; these qualitatively exhibit the features of vortex onset and location noted above.

Electrical strength of vacuum gap at repetitive breakdown

International Nuclear Information System (INIS)

Dubinin, N.P.; Chistyakov, N.P.

1983-01-01

The investigation of repetitive pulse breakdown of vacuum space, which electrodes have been subjected to various treatment in vacuum and inert gas, is carried out. In case of electrode warm-up in vacuum up to 400 deg C as well as electronic heating up to 900 deg C the voltage in case of repetitive breakdown hasncreased approximately twice and in case of a through treatment, which is accomplished by a high-current glow discharge in inert gas, the maximum high voltage in case of the first breakdown at repetitive breakdown has decreased by 30...40%, remaining 2-3 times higher than in the first case

Measurement of skeletal muscle collagen breakdown by microdialysis

DEFF Research Database (Denmark)

Miller, B F; Ellis, D; Robinson, M M

2011-01-01

Exercise increases the synthesis of collagen in the extracellular matrix of skeletal muscle. Breakdown of skeletal muscle collagen has not yet been determined because of technical limitations. The purpose of the present study was to use local sampling to determine skeletal muscle collagen breakdown...... collagen breakdown 17–21 h post-exercise, and our measurement of OHP using GC–MS was in agreement with traditional assays....

48 CFR 252.236-7000 - Modification proposals-price breakdown.

Science.gov (United States)

2010-10-01

...-price breakdown. 252.236-7000 Section 252.236-7000 Federal Acquisition Regulations System DEFENSE... CLAUSES Text of Provisions And Clauses 252.236-7000 Modification proposals—price breakdown. As prescribed in 236.570(a), use the following clause: Modification Proposals—Price Breakdown (DEC 1991) (a) The...

Fundamental studies of passivity and passivity breakdown

International Nuclear Information System (INIS)

Macdonald, D.D.; Urquidi-Macdonald, M.; Song, H.; Biaggio-Rocha, S.; Searson, P.

1991-11-01

This report summarizes the findings of our fundamental research program on passivity and passivity breakdown. During the past three and one half years in this program (including the three year incrementally-funded grant prior to the present grant), we developed and experimentally tested various physical models for the growth and breakdown of passive films on metal surfaces. These models belong to a general class termed ''point defects models'' (PDMs), in which the growth and breakdown of passive films are described in terms of the movement of anion and cation vacancies

Pre-breakdown phenomena and discharges in a gas-liquid system

Science.gov (United States)

Tereshonok, D. V.; Babaeva, N. Yu; Naidis, G. V.; Panov, V. A.; Smirnov, B. M.; Son, E. E.

2018-04-01

In this paper, we investigate pre-breakdown and breakdown phenomena in gas-liquid systems. Cavitation void formation and breakdown in bubbles immersed in liquids are studied numerically, while complete breakdown of bubbled water is studied in experiments. It is shown that taking into account the dependence of water dielectric constant on electric field strength plays the same important role for cavitation void appearance under the action of electrostriction forces as the voltage rise time. It is also shown that the initial stage of breakdown in deformed bubbles immersed in liquid strongly depends on spatial orientation of the bubbles relative to the external electric field. The effect of immersed microbubbles, distributed in bulk water, on breakdown time and voltage is studied experimentally. At the breakdown voltage, the slow ‘thermal’ mechanism is changed by the fast ‘streamer-leader’ showing a decrease in breakdown time by two orders of magnitude by introducing microbubbles (0.1% of volumetric gas content) into the water. In addition, the plasma channel is found to pass between nearby microbubbles, exhibiting some ‘guidance’ effect.

Electrical breakdown of water in microgaps

International Nuclear Information System (INIS)

Schoenbach, Karl; Kolb, Juergen; Xiao Shu; Katsuki, Sunao; Minamitani, Yasushi; Joshi, Ravindra

2008-01-01

Experimental and modeling studies on electrical breakdown in water in submillimeter gaps between pin and plane electrodes have been performed. Prebreakdown, breakdown and recovery of the water gaps were studied experimentally by using optical and electrical diagnostics with a temporal resolution on the order of one nanosecond. By using Mach-Zehnder interferometry, the electric field distribution in the prebreakdown phase was determined by means of the Kerr effect. Electric fields values in excess of the computed electric fields, which reach >4 MV cm -1 for applied electrical pulses of 20 ns duration, were recorded at the tip of the pin electrode, an effect which can be explained by a reduced permittivity of water at high electric fields. Breakdown of the gaps, streamer-to-arc transition, was recorded by means of high-speed electrical diagnostics, and through high-speed photography. It was shown, through simulations, that breakdown is initiated by field emission at the interface of preexisting microbubbles. Impact ionization within the micro-bubble's gas then contributes to plasma development. Experiments using pulse-probe methods and Schlieren diagnostics allowed us to follow the development of the disturbance caused by the breakdown over a time of more than milliseconds and to determine the recovery time of a water switch. In order to trigger water switches a trigger electrode with a triple point has been utilized. The results of this research have found application in the construction of compact pulse power generators for bioelectric applications.

Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

International Nuclear Information System (INIS)

Thiyagarajan, Magesh; Thompson, Shane

2012-01-01

We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 μm radius spot size that produces laser intensities up to 3 - 6 TW/cm 2 , sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10 8 nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then scaled to

Protein Availability and Satellite Cell Dynamics in Skeletal Muscle.

Science.gov (United States)

Shamim, Baubak; Hawley, John A; Camera, Donny M

2018-06-01

Human skeletal muscle satellite cells are activated in response to both resistance and endurance exercise. It was initially proposed that satellite cell proliferation and differentiation were only required to support resistance exercise-induced hypertrophy. However, satellite cells may also play a role in muscle fibre remodelling after endurance-based exercise and extracellular matrix regulation. Given the importance of dietary protein, particularly branched chain amino acids, in supporting myofibrillar and mitochondrial adaptations to both resistance and endurance-based training, a greater understanding of how protein intake impacts satellite cell activity would provide further insight into the mechanisms governing skeletal muscle remodelling with exercise. While many studies have investigated the capacity for protein ingestion to increase post-exercise rates of muscle protein synthesis, few investigations have examined the role for protein ingestion to modulate satellite cell activity. Here we review the molecular mechanisms controlling the activation of satellite cells in response to mechanical stress and protein intake in both in vitro and in vivo models. We provide a mechanistic framework that describes how protein ingestion may enhance satellite activity and promote exercise adaptations in human skeletal muscle.

Kinetic parameters of protein metabolism in rats during protein-free feeding

International Nuclear Information System (INIS)

Krawielitzki, K.; Schadereit, R.; Wuensche, J.

1987-01-01

16 male rats of 100 g live weight were given 50 mg of a mixture containing 15 N-labelled amino acids as a single dose within a protein-free feeding period. Following this the 15 N excretion in feces and urine as well as the development of the 15 N excess in different organs and tissues were estimated over 3 days by slaughtering the animals within given 7 time intervals. Using a 3 pool model and the computer program for the interpretation of 15 N tracer experiments by Toewe et al. (1984), kinetic parameters such as the rate of protein synthesis, protein breakdown and the rate of reutilization were calculated. Despite a negative N balance (- 41.8 mg N/d) under protein-free conditions the protein metabolism of the rat shows high dynamics characterized by a high flux rate (225 mg N/d) and a high rate of body protein synthesis (181 mg/d). The reutilization was 85 %. Depending on time the 15 N excess in the tested organs and tissues showed significant differences and seems to demonstrate that under these conditions protein synthesis mainly takes place in the most important organs (e.g. intestinal tract, liver). Under protein-free feeding conditions protein synthesis and protein breakdown of the whole body seems to be slightly increased in comparison to N balanced feeding conditions. (author)

AVLIS Production Plant work breakdown structure and Dictionary

International Nuclear Information System (INIS)

1984-01-01

The work breakdown structure has been prepared for the AVLIS Production Plant to define, organize, and identify the work efforts and is summarized in Fig. 1-1 for the top three project levels. The work breakdown structure itself is intended to be the primary organizational tool of the AVLIS Production Plant and is consistent with the overall AVLIS Program Work Breakdown Structure. It is designed to provide a framework for definition and accounting of all of the elements that are required for the eventual design, procurement, and construction of the AVLIS Production Plant. During the present phase of the AVLIS Project, the conceptual engineering phase, the work breakdown structure is intended to be the master structure and project organizer of documents, designs, and cost estimates. As the master project organizer, the key role of the work breakdown structure is to provide the mechanism for developing completeness in AVLIS cost estimates and design development of all hardware and systems. The work breakdown structure provides the framework for tracking, on a one-to-one basis, the component design criteria, systems requirements, design concepts, design drawings, performance projections, and conceptual cost estimates. It also serves as a vehicle for contract reporting. 12 figures, 2 tables

Breakdown Characteristics Study on an 18 Cell X-band Structure

International Nuclear Information System (INIS)

Wang, F

2008-01-01

A CLIC designed 18 cells, low group velocity (2.4% to 1.0% c), X-band (11.4 GHz) accelerator structure (denoted T18) was designed at CERN, its cells were built at KEK, and it was assembled and tested at SLAC. An interesting feature of this structure is that the gradient in the last cell is about 50% higher than that in the first cell. This structure has been RF conditioned at SLAC NLCTA for about 1400 hours where it incurred about 2200 breakdowns. This paper presents the characteristics of these breakdowns, including (1) the breakdown rate dependence on gradient, pulse width and conditioning time, (2) the breakdown distribution along the structure, (3) relation between breakdown and pulsed heating dependence study and (4) electric field decay time for breakdown changing over the whole conditioning time. Overall, this structure performed very well, having a final breakdown rate of less than 1e-6/pulse/m at 106 MV/m with 230 ns pulse width

Breakdown Characteristics Study on an 18 Cell X-band Structure

International Nuclear Information System (INIS)

Wang Faya

2009-01-01

A CLIC designed 18 cells, low group velocity (2.4% to 1.0% c), X-band (11.4 GHz) accelerator structure (denoted T18) was designed at CERN, its cells were built at KEK, and it was assembled and tested at SLAC. An interesting feature of this structure is that the gradient in the last cell is about 50% higher than that in the first cell. This structure has been RF conditioned at SLAC NLCTA for about 1400 hours where it incurred about 2200 breakdowns. This paper presents the characteristics of these breakdowns, including 1) the breakdown rate dependence on gradient, pulse width and conditioning time, 2) the breakdown distribution along the structure, 3) relation between breakdown and pulsed heating dependence study and 4) electric field decay time for breakdown changing over the whole conditioning time. Overall, this structure performed very well, having a final breakdown rate of less than 1e-6/pulse/m at 106 MV/m with 230 ns pulse width.

Analysis on X-band structure breakdown at GLCTA

International Nuclear Information System (INIS)

Suehara, T.; Sanuki, T.; Komamiya, S.; Higo, T.; Hayano, H.; Terunuma, N.; Saeki, T.; Watanabe, K.; Hayakawa, A.; Tsukada, Y.

2004-01-01

We have built a new monitoring system for accelerator structure breakdown in the X-band high-gradient test facility at KEK (GLCTA: Global Linear Collider Test Accelerator). An X-band test structure KX01 (made by KEK) has been processed at GLCTA and we have been collecting data for about 3 months using this breakdown monitoring system. We describe overview of the monitoring system and preliminary result of breakdown analysis of the structure. (author)

Breakdown Cause and Effect Analysis. Case Study

Science.gov (United States)

Biały, Witold; Ružbarský, Juraj

2018-06-01

Every company must ensure that the production process proceeds without interferences. Within this article, the author uses the term "interferences" in reference to unplanned stoppages caused by breakdowns. Unfortunately, usually due to machine operators' mistakes, machines break, which causes stoppages thus generating additional costs for the company. This article shows a cause and effect analysis of a breakdown in a production process. The FMEA as well as quality management tools: the Ishikawa diagram and Pareto chart were used for the analysis. Correction measures were presented which allowed for a significant reduction in the number of stoppages caused by breakdowns.

Laser-induced breakdown spectroscopy analysis of asbestos

International Nuclear Information System (INIS)

Caneve, L.; Colao, F.; Fabbri, F.; Fantoni, R.; Spizzichino, V.; Striber, J.

2005-01-01

Laser-induced breakdown spectroscopy was applied to test the possibility of detecting and identifying asbestos in different samples in view of the perspective at field operation without sample preparation which is peculiar to this technique. Several like-resin materials were first investigated by laser-induced breakdown spectroscopy, in order to find an asbestos container assuring safe laboratory operation during the material characterization aimed to identify indicators suitable for a quick identification on field. Successively, spectra of asbestos samples of both in serpentine and amphibole forms were measured and the variability in elemental composition was calculated from the emission spectra. Ratios of intensities of characteristic elements were tested as indicators for asbestos recognition. Laser-induced breakdown spectroscopy results were compared with those obtained by analyzing the same asbestos samples with a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, a good correlation was found for Mg/Si and Fe/Si, thus showing the capability of laser-induced breakdown spectroscopy as a diagnostic tool for this category of materials. In particular, it was demonstrated that the method based on two indicators derived from laser-induced breakdown spectroscopy intensity ratios allows to discriminate between asbestos and cements in single shot measurements suitable to field operation

Breakdown resistance of refractory metals compared to copper

CERN Document Server

Taborelli, M; Kildemo, M

2004-01-01

The behaviour of Mo, W and Cu with respect to electrical breakdown in ultra high vacuum has been investigated by means of a capacitor discharge method. The maximum stable electric field without breakdown and the field enhancement factor, beta have been measured between electrodes of the same material in a sphere/plane geometry for anode and cathode, respectively. The maximum stable field increases as a function of the number of breakdown events for W and Mo. In contrast, no systematic increase is observed for Cu. The highest values obtained are typically 500 MV/m for W, 350 MV/m for Mo and only 180 MV/m for Cu. This conditioning, found for the refractory metals, corresponds to a simultaneous decrease of beta and is therefore related to the field emission properties of the surface and their modification upon sparking. Accordingly, high beta values and no applicable field increase occur for Cu even after repeated breakdown. The results are compared with RF breakdown experiments [1] performed on prototype 30 GHz...

Modeling Covariance Breakdowns in Multivariate GARCH

OpenAIRE

Jin, Xin; Maheu, John M

2014-01-01

This paper proposes a flexible way of modeling dynamic heterogeneous covariance breakdowns in multivariate GARCH (MGARCH) models. During periods of normal market activity, volatility dynamics are governed by an MGARCH specification. A covariance breakdown is any significant temporary deviation of the conditional covariance matrix from its implied MGARCH dynamics. This is captured through a flexible stochastic component that allows for changes in the conditional variances, covariances and impl...

Experimental Study on High Electrical Breakdown of Water Dielectric

International Nuclear Information System (INIS)

Zhang Zicheng; Zhang Jiande; Yang Jianhua

2005-01-01

By means of a coaxial apparatus, pressurized water breakdown experiments with microsecond charging have been carried out with different surface roughness of electrodes and different ethylene glycol concentrations of ethylene glycol/water mixture. The experimental results about the breakdown stress and the effective time are presented. The breakdown stress is normalized to the situation that the effective time is transformed to 1 μs and analyzed. The conclusions are as follows: (1) the breakdown stress formula is modified to E = 0.561M A -1/10 t eff -1/N P 1/8 ; (2) the coefficient M is significantly increased by surface polishing and ethylene glycol additive; (3) it is accumulative for the capacity of improving electrical breakdown strength for surface polishing, ethylene glycol additive, and pressurization, of which pressurization is the most effective method; (4) the highest stress of 235.5 kV/cm is observed in ethylene glycol/water mixture with an ethylene glycol concentration of 80% at a hydrostatic pressure of 1215.9 kPa and is about one time greater than that in pure water at constant pressure; (5) for pressurization and surface polishing, the primary mechanism to improve the breakdown strength of water dielectric is the increase in the breakdown time delay. Research results indicate great potential in the application of the high power pulse conditioning system of water dielectric

Influência da espessura de biofilmes feitos à base de proteínas miofibrilares sobre suas propriedades funcionais Thickness effects of myofibrillar protein based edible films on their functional properties

Directory of Open Access Journals (Sweden)

PAULO JOSÉ DO AMARAL SOBRAL

2000-06-01

Full Text Available O emprego potencial de filmes comestíveis e biodegradáveis em embalagens é condicionado pelas suas propriedades funcionais, que são influenciadas por muitos fatores, inclusive pela espessura. O objetivo deste trabalho foi estudar a influência da espessura dos biofilmes feitos à base de proteínas miofibrilares (de carne bovina e de tilápia-do-nilo sobre suas propriedades funcionais. Os biofilmes foram preparados a partir de uma solução filmogênica com 1 g de proteínas/100 g de solução. A concentração de plastificante foi de 45 g de glicerina/100 g de proteínas, e o pH foi mantido em 2,7. Após secagem, os filmes foram acondicionados em dessecadores a 58% de umidade relativa e 22°C, por quatro dias. As propriedades mecânicas foram determinadas por teste de perfuração; a permeabilidade ao vapor de água, por um método gravimétrico, e a cor e a opacidade, com colorímetro HunterLab, a 22°C. A força na perfuração, a permeabilidade ao vapor de água, a diferença de cor e a opacidade dos dois biofilmes aumentaram linearmente com a espessura dos corpos-de-prova. A deformação na perfuração foi pouco dependente da espessura e apresentou grande dispersão, em ambos os filmes. A taxa de permeabilidade ao vapor de água diminuiu linearmente com a espessura.Research on edible and biodegradable films had been promoted recently because of environmental concerns. The use of these materials for packaging applications is conditioned by their functional properties, which are influenced by many factors, including thickness. The objective of this work was to study the influence of thickness of myofibrillar protein-based biofilms on some of their functional properties. Biofilms were prepared from film forming solutions (FFS containing 1 g of protein/100 g of FFS. The plasticizer concentration was 45 g glycerin/100 g of protein and the pH was kept at 2.7. After drying, biofilms were conditioned in desiccators at 58% relative humidity and

Product Work Breakdown Structure

National Research Council Canada - National Science Library

Okayama, Y; Chirillo, L. D

1980-01-01

.... Any such subdivision scheme is a work breakdown structure. Traditional shipbuilders employ work subdivisions by ships functional systems which are natural and appropriate for estimating and for early design stages...

Experimental Study on Breakdown Characteristics of Transformer Oil Influenced by Bubbles

Directory of Open Access Journals (Sweden)

Chunxu Qin

2018-03-01

Full Text Available Bubbles will reduce the electric strength of transformer oil, and even result in the breakdown of the insulation. This paper has studied the breakdown voltages of transformer oil and oil-impregnated pressboard under alternating current (AC and direct current (DC voltages. In this paper, three types of electrodes were applied: cylinder-plan electrodes, sphere-plan electrodes, and cone-plan electrodes, and the breakdown voltages were measured in both no bubbles and bubbles. The sphere-sphere electrodes were used to study the breakdown voltage of the oil-impregnated pressboard. The results showed that under the influence of bubble, the breakdown voltage of the cylinder-plan electrode dropped the most, and the breakdown voltage of the cone-plan electrode dropped the least. The bubbles motion was the key factor of the breakdown. The discharge types of the oil-impregnated pressboard were different with bubbles, and under DC, the main discharge type was flashover along the oil-impregnated pressboard, while under AC, the main discharge type was breakdown through the oil-impregnated pressboard.

Gas breakdown in tokamaks

International Nuclear Information System (INIS)

Abramov, V.A.; Pogutse, O.P.; Yurchenko, Eh.I.

1975-01-01

The initial stage of the charge development in a tokomak is considered theoretically. It is supposed that all electrons produced in neutral gas ionisation process are in the regime of an almost continuous acceleration. The production time of a given electron density is calculated as a function of the neutral gas density and of parameters of the vortex electric field. The mechanism of plasma escape on walls is considered. It is shown that the escaping time is defined by a specific inertial flow of plasma and depends on whether chamber walls are metal or dielectric. The criterion of the gas breakdown in a toroidal system is formulated. The developed theory is shown to explain a strong dependence of the breakdown on the gas initial density [ru

The choice of label and measurement technique in tracer studies of body protein metabolism in man

International Nuclear Information System (INIS)

James, W.P.T.; Sender, P.M.; Garlick, P.J.; Waterlow, J.C.

1975-01-01

The turnover of non-serum proteins in man has had limited study despite the physiological importance of maintaining the balance between synthesis and breakdown of body proteins. Body protein is usually considered as a single pool and breakdown rates are often measured by monitoring excreted label at intervals after pulse labelling with radioactive or 15 N amino acids. No label has yet been used for measuring tissue protein breakdown in man which is free from the major problem of label re-utilization. All measurements of breakdown rates, eg. with 75 Se-selenomethionine, 15 N- or 14 C-glycine, give rate constants which are too low. The heterogeneity of body proteins also means that an estimate of the weighted average breakdown rate can only be obtained after following the excretion of isotope for a long period, perhaps of the order of 3-4 half-lives which, for man, would be 100 days after labelling. We therefore use infusions with either 14 C- or 15 N-labelled amino acids to measure breakdown and synthesis rates: these values are less affected by problems of protein heterogeneity. Single injection techniques are subject to more error than constant infusions of label because of the difficulty of defining the precursor activity. 15 N labelling need not be confined to essential amino acids if total protein rather than amino acid turnover is studied: the latter involves measurements of the labelled amino acid itself which is difficult with 15 N because of the small amounts of free amino acid nitrogen available. Carbon labelling of non-essential amino acids is unsuitable for studies of protein turnover and the choice of the position of the label on the molecule is important when labelled essential amino acids are employed. Short-term changes in protein metabolism are evaluated better with amino acids with a small pool size; the equilibration time in the excretory bicarbonate pool is also shorter than in the urea pool so that 15 N is less useful than carbon labelling. We

Breakdown of teenage placements in Danish out-of-home care

DEFF Research Database (Denmark)

Egelund, Tine; Olsson, Martin; Høst, Anders

2012-01-01

to breakdown. However, while the logistic regression model was significant, it explained only 6% of the variance. Earlier studies have indicated that breakdown is a substantial problem of child welfare in several other western countries, Denmark is no exception. These corresponding breakdown rates point out...

Dramatically enhanced electrical breakdown strength in cellulose nanopaper

Directory of Open Access Journals (Sweden)

Jianwen Huang

2016-09-01

Full Text Available Electrical breakdown behaviors of nanopaper prepared from nanofibrillated cellulose (NFC were investigated. Compared to conventional insulating paper made from micro softwood fibers, nanopaper has a dramatically enhanced breakdown strength. Breakdown field of nanopaper is 67.7 kV/mm, whereas that of conventional paper is only 20 kV/mm. Air voids in the surface of conventional paper are observed by scanning electron microscope (SEM. Further analyses using mercury intrusion show that pore diameter of conventional paper is around 1.7 μm, while that of nanopaper is below 3 nm. Specific pore size of nanopaper is determined to be approximately 2.8 nm by the gas adsorption technique. In addition, theoretical breakdown strengths of nanopaper and conventional paper are also calculated to evaluate the effect of pore size. It turns out that theoretical values agree well with experimental data, indicating that the improved strength in nanopaper is mainly attributed to the decreased pore size. Due to its outstanding breakdown strength, this study indicates the suitability of nanopaper for electrical insulation in ultra-high voltage convert transformers and other electrical devices.

Impact of Machine Breakdowns on Productivity

Directory of Open Access Journals (Sweden)

Anwaruddin Tanwari

2011-10-01

Full Text Available This paper reports the machine breakdowns and their impact on the total productivity for the FMCGs (Fast Moving Consumer Goods industry because higher productivity rate is important factor on which the customer services largely depend in this competitive business world. This paper also suggests that the machine breakdowns and other related problems within the plant are due to improper care, keeping the plant operative for twenty four hours a day, seven days a week without any break and lack of management\\'s concentration towards these issues. These break-downs results in un-timely closure of the plant and very poor production performance is achieved in the plant that affects the service level at great level. Realising the importance of maintenance in improving productivity and service, an attempt has been made in this paper to study the scope of maintenance with the help of a case study.

Numerical simulation and physical aspects of supersonic vortex breakdown

Science.gov (United States)

Liu, C. H.; Kandil, O. A.; Kandil, H. A.

1993-01-01

Existing numerical simulations and physical aspects of subsonic and supersonic vortex-breakdown modes are reviewed. The solution to the problem of supersonic vortex breakdown is emphasized in this paper and carried out with the full Navier-Stokes equations for compressible flows. Numerical simulations of vortex-breakdown modes are presented in bounded and unbounded domains. The effects of different types of downstream-exit boundary conditions are studied and discussed.

Breakdown-prone volume in terahertz wave beams

Energy Technology Data Exchange (ETDEWEB)

Nusinovich, G. S.; Qiao, F.; Kashyn, D. G.; Pu, R. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742-3511 (United States); Dolin, L. S. [Institute of Applied Physics, Nizhny Novgorod 603600 (Russian Federation)

2013-06-21

This study was motivated by the recently proposed concept of remote detection of concealed radioactive materials by a focused terahertz (THz) radiation [V. L. Granatstein and G. S. Nusinovich, J. Appl. Phys. 108, 063304 (2010)]. According to this concept, a high-power THz radiation should be focused in a small spot where the field intensity exceeds the breakdown threshold. In the presence of free electrons in such a breakdown-prone volume, a THz discharge will occur there. However, this volume should be so small that in the absence of ionizing sources in its vicinity the probability to have there any free electrons is low. Then, the increased breakdown rate in a series of THz pulses would indicate the presence of hidden radioactive materials in the vicinity of the focused spot. For this concept, it is important to accurately determine the breakdown-prone volume created by a focused THz radiation. This problem is analyzed in this paper, first, for the case of a single wave beam and, then, for the case of crossing wave beams of different polarizations. The problem is studied first ignoring the diffraction spread of wave beams in the vicinity of the focal plane and, then, with the account for the diffraction spreading. Then, relations between the THz wave power, the range of such a system and the breakdown-prone volume are analyzed. Finally, the effect of the atmospheric turbulence on propagation and focusing of THz wave beams in air is considered.

Breakdown-prone volume in terahertz wave beams

International Nuclear Information System (INIS)

Nusinovich, G. S.; Qiao, F.; Kashyn, D. G.; Pu, R.; Dolin, L. S.

2013-01-01

This study was motivated by the recently proposed concept of remote detection of concealed radioactive materials by a focused terahertz (THz) radiation [V. L. Granatstein and G. S. Nusinovich, J. Appl. Phys. 108, 063304 (2010)]. According to this concept, a high-power THz radiation should be focused in a small spot where the field intensity exceeds the breakdown threshold. In the presence of free electrons in such a breakdown-prone volume, a THz discharge will occur there. However, this volume should be so small that in the absence of ionizing sources in its vicinity the probability to have there any free electrons is low. Then, the increased breakdown rate in a series of THz pulses would indicate the presence of hidden radioactive materials in the vicinity of the focused spot. For this concept, it is important to accurately determine the breakdown-prone volume created by a focused THz radiation. This problem is analyzed in this paper, first, for the case of a single wave beam and, then, for the case of crossing wave beams of different polarizations. The problem is studied first ignoring the diffraction spread of wave beams in the vicinity of the focal plane and, then, with the account for the diffraction spreading. Then, relations between the THz wave power, the range of such a system and the breakdown-prone volume are analyzed. Finally, the effect of the atmospheric turbulence on propagation and focusing of THz wave beams in air is considered.

Prolonged bed rest decreases skeletal muscle and whole body protein synthesis

Science.gov (United States)

Ferrando, A. A.; Lane, H. W.; Stuart, C. A.; Davis-Street, J.; Wolfe, R. R.

1996-01-01

We sought to determine the extent to which the loss of lean body mass and nitrogen during inactivity was due to alterations in skeletal muscle protein metabolism. Six male subjects were studied during 7 days of diet stabilization and after 14 days of stimulated microgravity (-6 degrees bed rest). Nitrogen balance became more negative (P protein synthesis (PS; P protein also decreased by 46% (P protein breakdown and inward transport. Whole body protein synthesis determined by [15N]alanine ingestion on six subjects also revealed a 14% decrease (P protein breakdown change significantly. These results indicate that the loss of body protein with inactivity is predominantly due to a decrease in muscle PS and that this decrease is reflected in both whole body and skeletal muscle measures.

Local NSAID infusion does not affect protein synthesis and gene expression in human muscle after eccentric exercise

DEFF Research Database (Denmark)

Mikkelsen, U R; Schjerling, P; Helmark, Ida Carøe

2010-01-01

models, and inhibit the exercise-induced satellite cell proliferation and protein synthesis in humans. However, the cellular mechanisms eliciting these responses remain unknown. Eight healthy male volunteers performed 200 maximal eccentric contractions with each leg. To block prostaglandin synthesis...... locally in the skeletal muscle, indomethacin (NSAID) was infused for 7.5 h via microdialysis catheters into m. vastus lateralis of one leg. Protein synthesis was determined by the incorporation of 1,2-(13)C(2) leucine into muscle protein from 24 to 28 h post-exercise. Furthermore, mRNA expression...... of selected genes was measured in muscle biopsies (5 h and 8 days post-exercise) by real-time reverse transcriptase PCR. Myofibrillar and collagen protein synthesis were unaffected by the local NSAID infusion. Five hours post-exercise, the mRNA expression of cyclooxygenase-2 (COX2) was sixfold higher...

The Work Breakdown Structure in an Acquisition Reform Environment

National Research Council Canada - National Science Library

Albert, Neil

1997-01-01

These viewgraphs discuss acquisition reform, costs, provide a definition for work breakdown structure, development process of work breakdown, an overview of contract business management, a GAO review...

Plasma breakdown in a capacitively-coupled radiofrequency argon discharge

Science.gov (United States)

Smith, H. B.; Charles, C.; Boswell, R. W.

1998-10-01

Low pressure, capacitively-coupled rf discharges are widely used in research and commercial ventures. Understanding of the non-equilibrium processes which occur in these discharges during breakdown is of interest, both for industrial applications and for a deeper understanding of fundamental plasma behaviour. The voltage required to breakdown the discharge V_brk has long been known to be a strong function of the product of the neutral gas pressure and the electrode seperation (pd). This paper investigates the dependence of V_brk on pd in rf systems using experimental, computational and analytic techniques. Experimental measurements of V_brk are made for pressures in the range 1 -- 500 mTorr and electrode separations of 2 -- 20 cm. A Paschen-style curve for breakdown in rf systems is developed which has the minimum breakdown voltage at a much smaller pd value, and breakdown voltages which are significantly lower overall, than for Paschen curves obtained from dc discharges. The differences between the two systems are explained using a simple analytic model. A Particle-in-Cell simulation is used to investigate a similar pd range and examine the effect of the secondary emission coefficient on the rf breakdown curve, particularly at low pd values. Analytic curves are fitted to both experimental and simulation results.

Criterion for vortex breakdown on shock wave and streamwise vortex interactions.

Science.gov (United States)

Hiejima, Toshihiko

2014-05-01

The interactions between supersonic streamwise vortices and oblique shock waves are theoretically and numerically investigated by three-dimensional (3D) Navier-Stokes equations. Based on the two inequalities, a criterion for shock-induced breakdown of the streamwise vortex is proposed. The simple breakdown condition depends on the Mach number, the swirl number, the velocity deficit, and the shock angle. According to the proposed criterion, the breakdown region expands as the Mach number increases. In numerical simulations, vortex breakdown appeared under conditions of multiple pressure increases and the helicity disappeared behind the oblique shock wave along the line of the vortex center. The numerical results are consistent with the predicted breakdown condition at Mach numbers 2.0 and 3.0. This study also found that the axial velocity deficit is important for classifying the breakdown configuration.

Development of Hybrid Product Breakdown Structure for NASA Ground Systems

Science.gov (United States)

Monaghan, Mark W.; Henry, Robert J.

2013-01-01

The Product Breakdown Structure is traditionally a method of identification of the products of a project in a tree structure. It is a tool used to assess, plan, document, and display the equipment requirements for a project. It is part of a product based planning technique, and attempts to break down all components of a project in as much detail as possible, so that nothing is overlooked. The PBS for ground systems at the Kennedy Space Center is being developed to encompass the traditional requirements including the alignment of facility, systems, and components to the organizational hierarchy. The Ground Operations Product Breakdown Structure is a hybrid in nature in that some aspects of a work breakdown structure will be incorporated and merged with the Architecture Concept of Operations, Master Subsystem List, customer interface, and assigned management responsibility. The Ground Operations Product Breakdown Structure needs to be able to identify the flexibility of support differing customers (internal and external) usage of ground support equipment within the Kennedy Space Center launch and processing complex. The development of the Product Breakdown Structure is an iterative activity Initially documenting the organization hierarchy structure and relationships. The Product Breakdown Structure identifies the linkage between the customer program requirements, allocation of system resources, development of design goals, and identification logistics products. As the Product Breakdown Structure progresses the incorporation of the results of requirement planning for the customer occurs identifying facility needs and systems. The mature Product Breakdown Structure is baselined with a hierarchical drawing, the Product Breakdown Structure database, and an associated document identifying the verification of the data through the life cycle of the program/product line. This paper will document, demonstrate, and identify key aspects of the life cycle of a Hybrid Product

Simulation of a three-dimensional vortex breakdown

Science.gov (United States)

Liu, C. H.; Menne, Stefan

1989-01-01

The breakdown of a vortex flow in a tube is studied for a slightly diverging tube by means of a numerical solution of the Navier-Stokes equations for a quasi-stationary, incompressible, laminar flow. Numerical results are compared to experiments of Faler and Leibovich. The numerical data display features similar to the experimental results concerning breakdown conditions, location, and structure.

Effects of heat on meat proteins - Implications on structure and quality of meat products.

Science.gov (United States)

Tornberg, E

2005-07-01

Globular and fibrous proteins are compared with regard to structural behaviour on heating, where the former expands and the latter contracts. The meat protein composition and structure is briefly described. The behaviour of the different meat proteins on heating is discussed. Most of the sarcoplasmic proteins aggregate between 40 and 60 °C, but for some of them the coagulation can extend up to 90°C. For myofibrillar proteins in solution unfolding starts at 30-32°C, followed by protein-protein association at 36-40°C and subsequent gelation at 45-50°C (conc.>0.5% by weight). At temperatures between 53 and 63°C the collagen denaturation occurs, followed by collagen fibre shrinkage. If the collagen fibres are not stabilised by heat-resistant intermolecular bonds, it dissolves and forms gelatine on further heating. The structural changes on cooking in whole meat and comminuted meat products, and the alterations in water-holding and texture of the meat product that it leads to, are then discussed.

A Real-time Breakdown Prediction Method for Urban Expressway On-ramp Bottlenecks

Science.gov (United States)

Ye, Yingjun; Qin, Guoyang; Sun, Jian; Liu, Qiyuan

2018-01-01

Breakdown occurrence on expressway is considered to relate with various factors. Therefore, to investigate the association between breakdowns and these factors, a Bayesian network (BN) model is adopted in this paper. Based on the breakdown events identified at 10 urban expressways on-ramp in Shanghai, China, 23 parameters before breakdowns are extracted, including dynamic environment conditions aggregated with 5-minutes and static geometry features. Different time periods data are used to predict breakdown. Results indicate that the models using 5-10 min data prior to breakdown performs the best prediction, with the prediction accuracies higher than 73%. Moreover, one unified model for all bottlenecks is also built and shows reasonably good prediction performance with the classification accuracy of breakdowns about 75%, at best. Additionally, to simplify the model parameter input, the random forests (RF) model is adopted to identify the key variables. Modeling with the selected 7 parameters, the refined BN model can predict breakdown with adequate accuracy.

Determining the mode of high voltage breakdowns in vacuum devices

International Nuclear Information System (INIS)

Miller, H.C.; Furno, E.J.; Sturtz, J.P.

1980-01-01

Devices were constructed which were essentially vacuum diodes equipped with windows allowing observation of high voltage breakdowns. The waveform of the applied voltage was photographed, and the x-ray output was monitored to investigate electrical breakdown in these vacuum diodes. Results indicate that breakdowns may be divided into two types: (1) vacuum (interelectrode) breakdown - characterized by a diffuse moderately bright discharge, a relative slow and smooth voltage collapse, and a large burst of x-rays, and (2) surface (insulator) flashover - characterized by a bright discharge with a very bright filamentary core, a relatively fast and noisy voltage collapse and no x-ray burst. Useful information concerning the type of breakdown in a vacuum device can be obtained by monitoring the voltage (current) waveform and the x-ray output

Supersonic quasi-axisymmetric vortex breakdown

Science.gov (United States)

Kandil, Osama A.; Kandil, Hamdy A.; Liu, C. H.

1991-01-01

An extensive computational study of supersonic quasi-axisymmetric vortex breakdown in a configured circular duct is presented. The unsteady, compressible, full Navier-Stokes (NS) equations are used. The NS equations are solved for the quasi-axisymmetric flows using an implicit, upwind, flux difference splitting, finite volume scheme. The quasi-axisymmetric solutions are time accurate and are obtained by forcing the components of the flowfield vector to be equal on two axial planes, which are in close proximity of each other. The effect of Reynolds number, for laminar flows, on the evolution and persistence of vortex breakdown, is studied. Finally, the effect of swirl ration at the duct inlet is investigated.

Abrupt onset of muscle dysfunction after treatment for Grave's disease: a case report.

Science.gov (United States)

Hernán Martínez, José; Sánchez, Alfredo; Torres, Oberto; Palermo, Coromoto; Santiago, Mónica; Figueroa, Carlos; Trinidad, Rafael; Mangual, Michelle; Gutierrez, Madeleine; González, Eva; Miranda, María de Lourdes

2014-01-01

Myopathy is a known complication of hypothyroidism, commonly characterized by an elevation in Creatine Kinase (CPK) due to increase capillary permeability proportional to the hypothyroid state. Thyroid hormone is important for the expression of fast myofibrillar proteins in the muscle. In hypothyroidism the expression of these proteins are deficient and there is an increase accumulation of slow myofibrillar proteins. A rapid or abrupt descend in thyroid hormones caused by radioiodine therapy after prolonged hyperthyroidism can lead to local hypothyroid state within the muscle tissue, resulting in CPK elevation and hypothyroid myopathy. Hormone replacement leads to resolution of symptoms and normalization of muscle enzymes serum levels.

Studies on gas breakdown in pulsed radio frequency atmospheric pressure glow discharges

International Nuclear Information System (INIS)

Huo, W. G.; Jian, S. J.; Yao, J.; Ding, Z. F.

2014-01-01

In pulsed RF atmospheric pressure glow discharges, the gas breakdown judged by the rapid drop in the amplitude of the pulsed RF voltage is no longer universally true. The steep increment of the plasma-absorbed RF power is proposed to determine the gas breakdown. The averaged plasma-absorbed RF power over a pulse period is used to evaluate effects of the preceding pulsed RF discharge on the breakdown voltage of the following one, finding that the breakdown voltage decreases with the increment in the averaged plasma-absorbed RF power under constant pulse duty ratio. Effects of the pulse off-time on the breakdown voltage and the breakdown delay time are also studied. The obtained dependence of the breakdown voltage on the pulse off-time is indicative of the transitional plasma diffusion processes in the afterglow. The breakdown voltage varies rapidly as the plasma diffuses fast in the region of moderate pulse off-time. The contribution of nitrogen atom recombination at the alumina surface is demonstrated in the prolonged memory effect on the breakdown delay time vs. the pulse off-time and experimentally validated by introducing a trace amount of nitrogen into argon at short and long pulse off-times

Optimal Rules for Single Machine Scheduling with Stochastic Breakdowns

Directory of Open Access Journals (Sweden)

Jinwei Gu

2014-01-01

Full Text Available This paper studies the problem of scheduling a set of jobs on a single machine subject to stochastic breakdowns, where jobs have to be restarted if preemptions occur because of breakdowns. The breakdown process of the machine is independent of the jobs processed on the machine. The processing times required to complete the jobs are constants if no breakdown occurs. The machine uptimes are independently and identically distributed (i.i.d. and are subject to a uniform distribution. It is proved that the Longest Processing Time first (LPT rule minimizes the expected makespan. For the large-scale problem, it is also showed that the Shortest Processing Time first (SPT rule is optimal to minimize the expected total completion times of all jobs.

Breakdown processes in wire chambers, prevention and rate capability

International Nuclear Information System (INIS)

Atac, M.

1983-01-01

Breakdowns were optically and electronically observed in drift tubes and drift chambers. They occur at a critical gain for given intensity in a gas mixture when ultraviolet photons are not completely quenched. It was observed that the breakdowns depended critically on average current for a given gas mixture independent of the size of the drift tubes used. Using 4.6% ethyl alcohol vapor mixed into 50/50 argon ethane gas, breakdown are eliminated up to 7 /sub μ/A average current drawn by pulses on a 1 cm section of an anode wire under an intense source. Pulses with an avalanche size of 10 6 electron rates above 10 6 pulses per centimeter per wire may be obtained with the elimination of breakdowns

Breakdown processes in wire chambers, prevention and rate capability

International Nuclear Information System (INIS)

Atac, M.

1982-01-01

Breakdowns were optically and electronically observed in drift tubes and drift chambers. They occur at a critical gain for given intensity in a gas mixture when ultraviolet photons are not completely quenched. It was observed that the breakdowns depended critically on average current for a given gas mixture independent of the size of the drift tubes used. Using 4.6% ethyl alcohol vapor mixed into 50/50 argon ethane gas, breakdowns are eliminated up to 7 μA average current drawn by pulses on a 1 cm section of an anode wire under an intense source. Pulses with an avalanche size of 10 6 electron rates above 10 6 pulses per centimeter per wire may be obtained with the elimination of breakdowns

Effect of neutron irradiation on the breakdown voltage of power MOSFET's

International Nuclear Information System (INIS)

Hasan, S.M.Y.; Kosier, S.L.; Schrimpf, R.D.; Galloway, K.F.

1994-01-01

The effect of neutron irradiation on power metal-oxide-semiconductor field effect transistor (power MOSFET) breakdown voltage has been investigated. Transistors with various breakdown voltage ratings were irradiated in a TRIGA nuclear reactor with cumulative fluence levels up to 5 x 10 14 neutrons/cm 2 (1 MeV equivalent). Noticeable increases in the breakdown voltages are observed in n-type MOSFET's after 10 13 neutrons/cm 2 and in p-type MOSFETs after 10 12 neutrons/cm 2 . An increase in breakdown voltage of as much as 30% is observed after 5 x 10 14 neutrons/cm 2 . The increase in breakdown voltage is attributed to the neutron-irradiation-induced defects which decrease the mean free path and trap majority carriers in the space charge region. The effect of positive trapped oxide charge due to concomitant gamma radiation and the effect of the termination structure on the increase in breakdown voltage are considered. An empirical model is presented to predict the value of the breakdown voltage as a function of neutron fluence

Ac breakdown in near-atmospheric pressure noble gases: I. Experiment

International Nuclear Information System (INIS)

Sobota, A; Kanters, J H M; Van Veldhuizen, E M; Haverlag, M; Manders, F; Gendre, M F; Hendriks, J

2011-01-01

Ac-driven breakdown processes have been explored much less than the pulsed or dc breakdown, even though they have possible applications in industry. This paper focuses on the frequency range between 60 kHz and 1 MHz, at a pin-pin electrode geometry and gap lengths of 4 or 7 mm. The breakdown process was examined in argon and xenon at 0.3 and 0.7 bar. We used electrical and optical measurements to characterize the breakdown process, to observe the influence of frequency change and the effect of ignition enhancers-UV irradiation and radioactive material.

Ac breakdown in near-atmospheric pressure noble gases: I. Experiment

Energy Technology Data Exchange (ETDEWEB)

Sobota, A; Kanters, J H M; Van Veldhuizen, E M; Haverlag, M [Eindhoven University of Technology, Department of Applied Physics, Postbus 513, 5600MB Eindhoven (Netherlands); Manders, F; Gendre, M F; Hendriks, J, E-mail: a.sobota@tue.nl [Philips Lighting, LightLabs, Mathildelaan 1, 5600JM Eindhoven (Netherlands)

2011-06-08

Ac-driven breakdown processes have been explored much less than the pulsed or dc breakdown, even though they have possible applications in industry. This paper focuses on the frequency range between 60 kHz and 1 MHz, at a pin-pin electrode geometry and gap lengths of 4 or 7 mm. The breakdown process was examined in argon and xenon at 0.3 and 0.7 bar. We used electrical and optical measurements to characterize the breakdown process, to observe the influence of frequency change and the effect of ignition enhancers-UV irradiation and radioactive material.

Light-load resistance exercise increases muscle protein synthesis and hypertrophy signaling in elderly men

DEFF Research Database (Denmark)

Agergaard, Jakob; Bülow, Jacob; Jensen, Jacob K

2017-01-01

to 13 h of supine rest. After 2.5 h of rest, unilateral LL-RE, consisting of leg extensions (10 sets, 36 repetitions) at 16% of 1 repetition maximum (RM), was conducted. Subsequently, the subjects were randomized to oral intake of 4 g of whey protein per hour (PULSE, n = 10), 28 g of whey protein at 0 h...... and 12 g of whey protein at 7 h postexercise (BOLUS, n = 10), or 4 g of maltodextrin per hour (placebo, n = 10). Quadriceps muscle biopsies were taken at 0, 3, 7, and 10 h postexercise from the resting and the exercised leg of each subject. Myofibrillar FSR and activity of select targets from...... persisted in the placebo group only. Levels of phosphorylated (T37/46) eukaryotic translation initiation factor 4E-binding protein 1 increased throughout the postexercise period in the exercised leg in the placebo and BOLUS groups and peaked at 7 h. In all three groups, phosphorylated (T56) eukaryotic...

The Electrical Breakdown of Thin Dielectric Elastomers

DEFF Research Database (Denmark)

Zakaria, Shamsul Bin; Morshuis, Peter H. F.; Yahia, Benslimane Mohamed

2014-01-01

Dielectric elastomers are being developed for use in actuators, sensors and generators to be used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. In order to obtain maximum efficiency, the devices are operated at high electrical fields....... This increases the likelihood for electrical breakdown significantly. Hence, for many applications the performance of the dielectric elastomers is limited by this risk of failure, which is triggered by several factors. Amongst others thermal effects may strongly influence the electrical breakdown strength....... In this study, we model the electrothermal breakdown in thin PDMS based dielectric elastomers in order to evaluate the thermal mechanisms behind the electrical failures. The objective is to predict the operation range of PDMS based dielectric elastomers with respect to the temperature at given electric field...

A case report: a heterozygous deletion (2791_2805 del) in exon 18 of the filamin C gene causing filamin C-related myofibrillar myopathies in a Chinese family.

Science.gov (United States)

Miao, Jing; Su, Fei-Fei; Liu, Xue-Mei; Wei, Xiao-Jing; Yuan, Yun; Yu, Xue-Fan

2018-06-04

Filamin C-related myofibrillar myopathies (MFM) are progressive skeletal myopathies with an autosomal dominant inheritance pattern. The conditions are caused by mutations of the filamin C gene (FLNC) located in the chromosome 7q32-q35 region. Genetic variations in the FLNC gene result in various clinical phenotypes. We describe a 43-year-old woman who suffered filamin C-related MFM, with symptoms first presenting in the proximal muscles of the lower limbs and eventually spreading to the upper limbs and distal muscles. The patient's serum level of creatine kinase was mildly increased. Mildy myopathic changes in the electromyographic exam and moderate lipomatous alterations in lower limb MRI were found. Histopathological examination revealed increased muscle fiber size variability, disturbances in oxidative enzyme activity, and the presence of abnormal protein aggregates and vacuoles in some muscle fibers. Ultrastructural analysis showed inclusions composed of thin filaments and interspersed granular densities. DNA sequencing analysis detected a novel 15-nucleotide deletion (c.2791_2805del, p.931_935del) in the FLNC gene. The patient's father, sister, brother, three paternal aunts, one paternal uncle, and the uncle's son also had slowly progressive muscle weakness, and thus, we detected an autosomal dominant inheritance pattern of the disorder. A novel heterogeneous 15-nucleotide deletion (c.2791_2805del, p.931_935del) in the Ig-like domain 7 of the FLNC gene was found to cause filamin C-related MFM. This deletion in the FLNC gene causes protein aggregation, abnormalities in muscle structure, and impairment in muscle fiber function, which leads to muscle weakness.

Breakdown of mucin as barrier to digestive enzymes in the ischemic rat small intestine.

Directory of Open Access Journals (Sweden)

Marisol Chang

Full Text Available Loss of integrity of the epithelial/mucosal barrier in the small intestine has been associated with different pathologies that originate and/or develop in the gastrointestinal tract. We showed recently that mucin, the main protein in the mucus layer, is disrupted during early periods of intestinal ischemia. This event is accompanied by entry of pancreatic digestive enzymes into the intestinal wall. We hypothesize that the mucin-containing mucus layer is the main barrier preventing digestive enzymes from contacting the epithelium. Mucin breakdown may render the epithelium accessible to pancreatic enzymes, causing its disruption and increased permeability. The objective of this study was to investigate the role of mucin as a protection for epithelial integrity and function. A rat model of 30 min splanchnic arterial occlusion (SAO was used to study the degradation of two mucin isoforms (mucin 2 and 13 and two epithelial membrane proteins (E-cadherin and toll-like receptor 4, TLR4. In addition, the role of digestive enzymes in mucin breakdown was assessed in this model by luminal inhibition with acarbose, tranexamic acid, or nafamostat mesilate. Furthermore, the protective effect of the mucin layer against trypsin-mediated disruption of the intestinal epithelium was studied in vitro. Rats after SAO showed degradation of mucin 2 and fragmentation of mucin 13, which was not prevented by protease inhibition. Mucin breakdown was accompanied by increased intestinal permeability to FITC-dextran as well as degradation of E-cadherin and TLR4. Addition of mucin to intestinal epithelial cells in vitro protected against trypsin-mediated degradation of E-cadherin and TLR4 and reduced permeability of FITC-dextran across the monolayer. These results indicate that mucin plays an important role in the preservation of the mucosal barrier and that ischemia but not digestive enzymes disturbs mucin integrity, while digestive enzymes actively mediate epithelial cell

Studies of RF Breakdown of Metals in Dense Gases

CERN Document Server

Hanlet, Pierrick M; Ankenbrandt, Charles; Johnson, Rolland P; Kaplan, Daniel; Kuchnir, Moyses; Moretti, Alfred; Paul, Kevin; Popovic, Milorad; Yarba, Victor; Yonehara, Katsuya

2005-01-01

A study of RF breakdown of metals in gases has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 800 MHz test cell has been used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, chromium, and beryllium electrodes as functions of hydrogen and helium gas density. These results are compared to the predicted or known RF breakdown behavior of these metals in vacuum.

A model of breakdown in parallel-plate detectors

International Nuclear Information System (INIS)

Fonte, P.

1996-01-01

Parallel-plate avalanche chambers (PPAC's) have many desirable properties, such as a fast, large area particle detector. However, the maximum gain is limited by a form of violent breakdown that limits the usefulness of this detector, despite its other evident qualities. The exact nature of this phenomenon is not yet sufficiently clear to sustain possible improvements. A previous experimental study is complemented in the present work by a quantitative model of the breakdown phenomenon in PPAC's, based on the streamer theory. The model reproduces well the peculiar behavior of the external current observed in PPAC's and resistive-plate chambers. Other breakdown properties measured in PPAC's are also well reproduced

Estimation of whole body protein turnover by L-[1-[sup 13]C]-leucine tracer experiment in post-viral hepatocirrhotic patients

Energy Technology Data Exchange (ETDEWEB)

Xinhua, Zhu; Zhenduo, Tang; Tengchang, Dai; Zongqin, Xia [Shanghai Second Medical Univ. (China)

1993-08-01

A constant infusion of L-[1-[sup 1]'3C]-leucine given to the subject and the plasma [sup 13]C-leucine enrichment and breath [sup 1]'3CO[sub 2] enrichment were measured with GC-MS and gas isotope ratio MS respectively. The plateau isotope enrichments reached were used to calculate the whole body protein synthesis and breakdown rates using a two pools model. 15 post-viral hepatocirrhotic patients and 6 normal adults were studied. The whole body protein synthesis and breakdown rates were both markedly increased in cirrhotic patients, with the breakdown rate higher than the synthesis rate and hence leading to a negative nitrogen balance. The changes of 7 decompensated cirrhotic patients were more severe than 8 compensated cirrhotic patients. The results suggest that the protein malnutrition and negative nitrogen balance of post-viral hepatocirrhotic patients are not simply due to low intake of protein and that the hyperactive turnover, especially the excessive breakdown of body protein might play an important role.

Neuromuscular electrical stimulation prior to presleep protein feeding stimulates the use of protein-derived amino acids for overnight muscle protein synthesis.

Science.gov (United States)

Dirks, Marlou L; Groen, Bart B L; Franssen, Rinske; van Kranenburg, Janneau; van Loon, Luc J C

2017-01-01

Short periods of muscle disuse result in substantial skeletal muscle atrophy. Recently, we showed that both neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. In this study, we test our hypothesis that NMES can augment the use of presleep protein-derived amino acids for overnight muscle protein synthesis in older men. Twenty healthy, older [69 ± 1 (SE) yr] men were subjected to 24 h of bed rest, starting at 8:00 AM. In the evening, volunteers were subjected to 70-min 1-legged NMES, while the other leg served as nonstimulated control (CON). Immediately following NMES, 40 g of intrinsically l-[1- 13 C]-phenylalanine labeled protein was ingested prior to sleep. Blood samples were taken throughout the night, and muscle biopsies were obtained from both legs in the evening and the following morning (8 h after protein ingestion) to assess dietary protein-derived l-[1- 13 C]-phenylalanine enrichments in myofibrillar protein. Plasma phenylalanine concentrations and plasma l-[1- 13 C]-phenylalanine enrichments increased significantly following protein ingestion and remained elevated for up to 6 h after protein ingestion (P protein-bound l-[1- 13 C]-phenylalanine enrichments (MPE) increased to a greater extent in the stimulated compared with the control leg (0.0344 ± 0.0019 vs. 0.0297 ± 0.0016 MPE, respectively; P protein-derived amino acids in the NMES compared with CON leg. In conclusion, application of NMES prior to presleep protein feeding stimulates the use of dietary protein-derived amino acids for overnight muscle protein synthesis in older men. Neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. Here we demonstrate that in older men after a day of bed rest, the application of NMES prior to presleep protein feeding stimulates the use of

Pre-breakdown light emission phenomena in low-pressure argon between parabolic electrodes

Energy Technology Data Exchange (ETDEWEB)

Wagenaars, E [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Perriens, N W B [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Brok, W J M [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Bowden, M D [Department of Physics and Astronomy, The Open University, Milton Keynes, MK7 6AA (United Kingdom); Veldhuizen, E M van [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Kroesen, G M W [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

2006-09-07

An experimental study on pre-breakdown light emission in low-pressure argon gas was performed. In a pulsed discharge, pre-breakdown phenomena were observed for repetition rates between 100 and 2000 Hz and pulse duration of 100 {mu}s. These phenomena were studied with time-resolved emission imaging using an intensified charge coupled device camera. The origin of the pre-breakdown emission was identified as diffusion of volume charges left over from previous discharges. These charges were accelerated towards the anode in small electron avalanches causing excitation of argon atoms. Different spatial distributions of the pre-breakdown light emission for different times between discharges were measured and the effects of the pre-breakdown phenomena on the main breakdown phase were studied using a double voltage pulse. The observed effects were attributed to the distribution of volume charges, left over from previous discharges, in the discharge gap during the pre-breakdown phase.

Project management strategies for prototyping breakdowns

DEFF Research Database (Denmark)

Granlien, Maren Sander; Pries-Heje, Jan; Baskerville, Richard

2009-01-01

, managing the explorative and iterative aspects of prototyping projects is not a trivial task. We examine the managerial challenges in a small scale prototyping project in the Danish healthcare sector where a prototype breakdown and project escalation occurs. From this study we derive a framework...... of strategies for coping with escalation in troubled prototyping projects; the framework is based on project management triangle theory and is useful when considering how to manage prototype breakdown and escalation. All strategies were applied in the project case at different points in time. The strategies led...

Hibernating black bears (Ursus americanus) experience skeletal muscle protein balance during winter anorexia.

Science.gov (United States)

Lohuis, T D; Harlow, H J; Beck, T D I

2007-05-01

Black bears spend four to seven months every winter confined to their den and anorexic. Despite potential for skeletal muscle atrophy and protein loss, bears appear to retain muscle integrity throughout winter dormancy. Other authors have suggested that bears are capable of net protein anabolism during this time. The present study was performed to test this hypothesis by directly measuring skeletal muscle protein metabolism during the summer, as well as early and late hibernation periods. Muscle biopsies were taken from the vastus lateralis of six free-ranging bears in the summer, and from six others early in hibernation and again in late winter. Protein synthesis and breakdown were measured on biopsies using (14)C-phenylalanine as a tracer. Muscle protein, nitrogen, and nucleic acid content, as well as nitrogen stable isotope enrichment, were also measured. Protein synthesis was greater than breakdown in summer bears, suggesting that they accumulate muscle protein during periods of seasonal food availability. Protein synthesis and breakdown were both lower in winter compared to summer but were equal during both early and late denning, indicating that bears are in protein balance during hibernation. Protein and nitrogen content, nucleic acid, and stable isotope enrichment measurements of the biopsies support this conclusion.

Surface breakdown igniter for mercury arc devices

Science.gov (United States)

Bayless, John R.

1977-01-01

Surface breakdown igniter comprises a semiconductor of medium resistivity which has the arc device cathode as one electrode and has an igniter anode electrode so that when voltage is applied between the electrodes a spark is generated when electrical breakdown occurs over the surface of the semiconductor. The geometry of the igniter anode and cathode electrodes causes the igniter discharge to be forced away from the semiconductor surface.

Sarcoplasmatic and myofibrillar protein changes caused by acute heat stress in broiler chicken Alterações nas proteínas sarcoplasmáticas e miofibrilares em frangos de corte causadas por estresse térmico agudo

Directory of Open Access Journals (Sweden)

Carolina de Castro Santos

2008-01-01

Full Text Available Acute heat stress (AHS modifies the structure of myofibrils affecting functional properties of meat, mainly the water holding capacity. This experiment aimed to identify changes in proteolysis and migration between the myofibrillar and sarcoplasmatic fractions due to pre-slaughter AHS. Myofibrillar fragmentation index (MFI, SDS-PAGE, western blot of vinculin (WB and shear force (SF were determined. Six hundred broilers (Gallus gallus were slaughtered in three different days (ST. In each ST, groups of ten animals were placed in transport crates and submitted to AHS (35ºC, 75 - 85% RH for 2 hours. Simultaneously, the non-stressed broilers (NS were kept in thermoneutral environment (22ºC, 83 ± 6.6% RH within the crates in the same density. After slaughter, the breast muscles were kept refrigerated until the withdrawal of all samples (0, 1, 2, 6 and 24 hours after slaughter. Sampling within AHS and NS birds was collected according to lightness value (normal L* 51, except for determination of MFI and SF. The lightness was used later to perform SDS-PAGE and WB analyses. MFI kinetics showed that the fragmentation rate was superior in animals NS, indicating that AHS can harm proteolysis and rate of myofibrillar fragmentation. However, the extent of fragmentation did not change, as well as SF values. SDS-PAGE for Troponin fragments indicated a differentiated pattern between AHS and NS. The WB did not show alterations in vinculin fragmentation. Modifications in sarcoplasmatic fraction are observed in meat with high L*values, independent of environmental condition.O estresse térmico agudo (ET causa alterações na estrutura das miofibrilas, afetando propriedades funcionais da carne, principalmente a capacidade de retenção de água. Identificaram-se mudanças na proteólise e migração entre as frações miofibrilar e sarcoplasmática, decorrentes do ET pré-abate, através do índice de fragmentação miofibrilar (MFI, SDS-PAGE para troponina (SDS

Protein metabolism in slow- and fast-twitch skeletal muscle during turpentine-induced inflammation.

Science.gov (United States)

Muthny, Tomas; Kovarik, Miroslav; Sispera, Ludek; Tilser, Ivan; Holecek, Milan

2008-02-01

The aim of our study was to evaluate the differences in protein and amino acid metabolism after subcutaneous turpentine administration in the soleus muscle (SOL), predominantly composed of red fibres, and the extensor digitorum longus muscle (EDL) composed of white fibres. Young rats (40-60 g) were injected subcutaneously with 0.2 ml of turpentine oil/100 g body weight (inflammation) or with the same volume of saline solution (control). Twenty-four hours later SOL and EDL were dissected and incubated in modified Krebs-Heinseleit buffer to estimate total and myofibrillar proteolysis, chymotrypsin-like activity of proteasome (CHTLA), leucine oxidation, protein synthesis and amino acid release into the medium. The data obtained demonstrate that in intact rats, all parameters measured except protein synthesis are significantly higher in SOL than in EDL. In turpentine treated animals, CHTLA increased and protein synthesis decreased significantly more in EDL. Release of leucine was inhibited significantly more in SOL. We conclude that turpentine-induced inflammation affects more CHTLA, protein synthesis and leucine release in EDL compared to SOL.

Liver and muscle protein metabolism in cachexia

NARCIS (Netherlands)

Peters, J.A.C.

2009-01-01

Up to 50% of cancer patients suffer from progressive weight loss (cachexia). Cachexia is induced by proinflammatory mediators (cytokines), induced by the tumor’s presence. These cytokines induce so-called acute phase protein synthesis by the liver, followed by skeletal muscle protein breakdown.

Breakdown of highly excited oxygen in a DC electric field

International Nuclear Information System (INIS)

Vagin, N.P.; Ionin, A.A.; Klimachev, Yu.M.; Sinitsin, D.V.; Yuryshev, N.N.; Deryugin, A.A.; Kochetov, I.V.; Napartovich, A.P.

2000-01-01

The breakdown of oxygen in a dc electric field is studied. A high concentration of oxygen molecules in the a 1 Δ g excited state is obtained in a purely chemical reactor. A decrease in the breakdown voltage at degrees of excitation exceeding 50% is observed. The theoretical decrement in the breakdown voltage obtained by solving the Boltzmann equation is in good agreement with the experimental data

Influence of water trees on breakdown voltage of polymeric cables insulations

Energy Technology Data Exchange (ETDEWEB)

Stancu, Cristina [INCDIE ICPE CA, Bucharest (Romania); Notingher, Petru V.; Plopeanu, Mihai Gabriel [Politehnica University of Bucharest, Bucharest (Romania)

2011-07-01

In a previous paper was shown that water trees development modifies considerably the electric field repartition, which increases significantly in the vicinity of treed areas. In order to find the water trees influence on the breakdown voltage, in the present paper, an experimental study on model cables insulated with low density polyethylene is done. In insulation samples, water trees with various dimensions and densities were developed. For the reduction of the test duration, an electric field with a higher frequency (3-5 kHz) was used. For breakdown voltage measurement an automatic setup was realized. For each value of the ageing time the dimensions and densities of water trees and breakdown voltage were measured and the dependency of the breakdown voltage with these quantities were analysed. The results show a significant reduction of the breakdown voltage of treed cables insulations compared to un-treed ones. Key words: polyethylene, water treeing, electric field, breakdown, power cables.

Contraction intensity and feeding affect collagen and myofibrillar protein synthesis rates differently in human skeletal muscle

DEFF Research Database (Denmark)

Holm, Lars; Hall, Gerrit van; Rose, Adam John

2010-01-01

Exercise stimulates muscle protein fractional synthesis rate (FSR) but the importance of contractile intensity and whether it interplays with feeding is not understood. This was investigated following two distinct resistance exercise (RE) contraction intensities using an intra-subject design...... to feeding. Further, although functionally linked, the contractile and the supportive matrix structures upregulate their protein synthesis rate quite differently in response to feeding and contractile-activity and -intensity....

Protein synthesis and degradation during starvation-induced cardiac atrophy in rabbits

International Nuclear Information System (INIS)

Samarel, A.M.; Parmacek, M.S.; Magid, N.M.; Decker, R.S.; Lesch, M.

1987-01-01

To determine the relative importance of protein degradation in the development of starvation-induced cardiac atrophy, in vivo fractional synthetic rates of total cardiac protein, myosin heavy chain, actin, light chain 1, and light chain 2 were measured in fed and fasted rabbits by continuous infusion of [ 3 H] leucine. In addition, the rate of left ventricular protein accumulation and loss were assessed in weight-matched control and fasted rabbits. Rates of total cardiac protein degradation were then estimated as the difference between rates of synthesis and growth. Fasting produced left ventricular atrophy by decreasing the rate of left ventricular protein synthesis (34.8 +/- 1.4, 27.3 +/- 3.0, and 19.3 +/- 1.2 mg/day of left ventricular protein synthesized for 0-, 3-, and 7-day fasted rabbits, respectively). Inhibition of contractile protein synthesis was evident by significant reductions in the fractional synthetic rates of all myofibrillar protein subunits. Although fractional rates of protein degradation increased significantly within 7 days of fasting, actual amounts of left ventricular protein degraded per day were unaffected. Thus, prolonged fasting profoundly inhibits the synthesis of new cardiac protein, including the major protein constituents of the myofibril. Both this inhibition in new protein synthesis as well as a smaller but significant reduction in the average half-lives of cardiac proteins are responsible for atrophy of the heart in response to fasting

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

Science.gov (United States)

Michels, Nathalie; Clarke, Gerard; Olavarria-Ramirez, Loreto; Gómez-Martínez, Sonia; Díaz, Ligia Esperanza; Marcos, Ascensión; Widhalm, Kurt; Carvalho, Livia A

2018-05-15

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. 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)-α, interferon (IFN)-ɣ, 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. 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-α in both populations). 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

Impact of Resistance Training on Skeletal Muscle Mitochondrial Biogenesis, Content, and Function

Directory of Open Access Journals (Sweden)

Thomas Groennebaek

2017-09-01

Full Text Available Skeletal muscle metabolic and contractile properties are reliant on muscle mitochondrial and myofibrillar protein turnover. The turnover of these specific protein pools is compromised during disease, aging, and inactivity. Oppositely, exercise can accentuate muscle protein turnover, thereby counteracting decay in muscle function. According to a traditional consensus, endurance exercise is required to drive mitochondrial adaptations, while resistance exercise is required to drive myofibrillar adaptations. However, concurrent practice of traditional endurance exercise and resistance exercise regimens to achieve both types of muscle adaptations is time-consuming, motivationally demanding, and contended to entail practice at intensity levels, that may not comply with clinical settings. It is therefore of principle interest to identify effective, yet feasible, exercise strategies that may positively affect both mitochondrial and myofibrillar protein turnover. Recently, reports indicate that traditional high-load resistance exercise can stimulate muscle mitochondrial biogenesis and mitochondrial respiratory function. Moreover, fatiguing low-load resistance exercise has been shown capable of promoting muscle hypertrophy and expectedly entails greater metabolic stress to potentially enhance mitochondrial adaptations. Consequently, fatiguing low-load resistance exercise regimens may possess the ability to stimulate muscle mitochondrial adaptations without compromising muscle myofibrillar accretion. However, the exact ability of resistance exercise to drive mitochondrial adaptations is debatable, not least due to some methodological challenges. The current review therefore aims to address the evidence on the effects of resistance exercise on skeletal muscle mitochondrial biogenesis, content and function. In prolongation, a perspective is taken on the specific potential of low-load resistance exercise on promoting mitochondrial adaptations.

G/sub o/ protein of fat cells: role in hormonal regulation of agonist-stimulated phosphatidyl inositol breakdown

International Nuclear Information System (INIS)

Rapiejko, P.J.; Northup, J.K.; Malbon, C.C.

1986-01-01

Incubating rat fat cell membranes in the presence of [ 32 P]NAD + and pertussis toxin (PT) results in the ADP-ribosylation of two peptides (M/sub r/ = 41,000 and 40,000). The 41,000-M/sub r/ peptide is the inhibitory G-protein of adenylate cyclase (G/sub i/). The 40,000-M/sub r/ peptide radiolabeled in the presence of [ 32 P]NAD + and PT has been purified from rabbit heart and bovine brain, but has not been identified uniformly in membranes of fat cells. Two rabbit polyclonal antisera raised against the alpha-subunit of bovine brain G/sub o/ were used to probe the nature of the 40,000-M/sub r/ peptide in rat fat cell membranes that had been separated by gel electrophoresis in the presence of sodium dodecyl sulfate and transferred electrophoretically to nitrocellulose. Both antisera specific for the alpha-subunit of G/sub o/ recognized the M/sub r/ = 40,000 peptide of fat cells that is ADP-ribosylated in the presence of PT. PT treatment of rat fat cells blocks epinephrine-stimulated inositol 1,4,5 trisphosphate (IP 3 ) generation. The inhibition of IP 3 generation by PT suggests a role for either G/sub i/ or G/sub o/ in receptor-mediated phosphatidyl inositol breakdown in the rat fat cell

RF Breakdown in Normal Conducting Single-Cell Structures

International Nuclear Information System (INIS)

Dolgashev, V.A.; Nantista, C.D.; Tantawi, S.G.; Higashi, Y.; Higo, T.

2006-01-01

Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape and material. Experimental and theoretical study of the effects of these parameters on the breakdown limit in full scale structures is difficult and costly. We use 11.4 GHz single-cell traveling wave and standing wave accelerating structures for experiments and modeling of rf breakdown behavior. These test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype multicell structures for the X-band linear collider. Fields elsewhere in the test structures are significantly lower than that of the single cell. The setup uses matched mode converters that launch the circular TM 01 mode into short test structures. The test structures are connected to the mode launchers with vacuum rf flanges. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. Simple 2D geometry of the test structures simplifies modeling of the breakdown currents and their thermal effects

Effects of streamwise vortex breakdown on supersonic combustion.

Science.gov (United States)

Hiejima, Toshihiko

2016-04-01

This paper presents a numerical simulation study of the combustion structure of streamwise vortex breakdown at Mach number 2.48. Hydrogen fuel is injected into a combustor at sonic speed from the rear of a hypermixer strut that can generate streamwise vortices. The results show that the burning behavior is enhanced at the points of the shock waves that are incident on the vortex and therefore the vortex breakdown in the subsonic region occurs due to combustion. The breakdown domain in the mainstream is found to form a flame-holding region suited to combustion and to lead to a stable combustion field with detached flames. In this way, streamwise vortex breakdown has an essential role in combustion enhancement and the formation of flames that hold under supersonic inflow conditions. Finally, the combustion property defined here is shown to coincide with the produced-water mass flow. This property shows that the amount of combustion is saturated at equivalence ratios over 0.4, although there is a slight increase beyond 1.

Work Breakdown Structures The Foundation for Project Management Excellence

CERN Document Server

Norman, Eric S; Fried, Robert T

2011-01-01

Understand and apply new concepts regarding Work Breakdown Structures The Work Breakdown Structure (WBS) has emerged as a foundational concept and tool in Project Management. It is an enabler that ensures clear definition and communication of project scope while performing a critical role as a monitoring and controlling tool. Created by the three experts who led the development of PMI's Practice Standard for Work Breakdown Structures, Second Edition, this much-needed text expands on what the standard covers and describes how to go about successfully implementing the WBS within the project life

High-voltage atmospheric breakdown across intervening rutile dielectrics.

Energy Technology Data Exchange (ETDEWEB)

Williamson, Kenneth Martin; Simpson, Sean; Coats, Rebecca Sue; Jorgenson, Roy Eberhardt; Hjalmarson, Harold Paul; Pasik, Michael Francis

2013-09-01

This report documents work conducted in FY13 on electrical discharge experiments performed to develop predictive computational models of the fundamental processes of surface breakdown in the vicinity of high-permittivity material interfaces. Further, experiments were conducted to determine if free carrier electrons could be excited into the conduction band thus lowering the effective breakdown voltage when UV photons (4.66 eV) from a high energy pulsed laser were incident on the rutile sample. This report documents the numerical approach, the experimental setup, and summarizes the data and simulations. Lastly, it describes the path forward and challenges that must be overcome in order to improve future experiments for characterizing the breakdown behavior for rutile.

Numerical study on physical mechanism of vortex breakdown occurrence in spin-up process

OpenAIRE

"小出, 輝明"; Teruaki", "Koide

2008-01-01

"A Numerical study presented on a vortex breakdown in spin-up process in an enclosed cylindrical container. In a transitional state, momentary vortex breakdowns can occur for particular parameter values ofthe Reynolds number and aspect ratio where no vortex breakdown appears in a steady state. This transient vortex breakdown flow is convenient to consider a mechanism for the occurrence of a vortex breakdown. It isdiscussed that periodical increase and decrease of angular momentum in upstream ...

Experimental research for vacuum gap breakdown in high voltage multi-pulse

International Nuclear Information System (INIS)

Huang Ziping; He Jialong; Chen Sifu; Deng Jianjun; Wang Liping

2008-01-01

Base on the breakdown theory of vacuum gaps, experiments have been done to find out the breakdown electric field intensities in high voltage single-and triple-pulse for 26 vacuum gaps with different shapes. The experimental results match up to the theory and confirm the effect of the pulse-number increase on the breakdown electric field intensity. The key point to decide the macroscopical breakdown electric field intensity of a vacuum gap has been pointed out with some advises about the design of a multi-pulse linear inductive accelerator's accelerate gap. (authors)

Vortex breakdown in a supersonic jet

Science.gov (United States)

Cutler, Andrew D.; Levey, Brian S.

1991-01-01

This paper reports a study of a vortex breakdown in a supersonic jet. A supersonic vortical jets were created by tangential injection and acceleration through a convergent-divergent nozzle. Vortex circulation was varied, and the nature of the flow in vortical jets was investigated using several types of flow visualization, including focusing schlieren and imaging of Rayleigh scattering from a laser light sheet. Results show that the vortical jet mixed much more rapidly with the ambient air than a comparable straight jet. When overexpanded, the vortical jet exhibited considerable unsteadiness and showed signs of vortex breakdown.

Scaling and volatility of breakouts and breakdowns in stock price dynamics.

Science.gov (United States)

Liu, Lu; Wei, Jianrong; Huang, Jiping

2013-01-01

Because the movement of stock prices is not only ubiquitous in financial markets but also crucial for investors, extensive studies have been done to understand the law behind it. In particular, since the financial crisis in 2008, researchers have a more interest in investigating large market volatilities in order to grasp changing market trends. In this work, we analyze the breakouts and breakdowns of both the Standard & Poor's 500 Index in the US stock market and the Shanghai Composite Index in the Chinese stock market. The breakout usually represents an ongoing upward trend in technical analysis while the breakdown represents an ongoing downward trend. Based on the renormalization method, we introduce two parameters to quantize breakouts and breakdowns, respectively. We discover scaling behavior, characterized by power-law distributions for both the breakouts and breakdowns in the two financial markets with different power-law exponents, which reflect different market volatilities. In detail, the market volatility for breakdowns is usually larger than that for breakouts. Moreover, as an emerging market, the Chinese stock market has larger market volatilities for both the breakouts and breakdowns than the US stock market (a mature market). Further, the short-term volatilities show similar features for both the US stock market and the Chinese stock market. However, the medium-term volatilities in the US stock market are almost symmetrical for the breakouts and breakdowns, whereas those in the Chinese stock market appear to be asymmetrical for the breakouts and breakdowns. The methodology presented here provides a way to understand scaling and hence volatilities of breakouts and breakdowns in stock price dynamics. Our findings not only reveal the features of market volatilities but also make a comparison between mature and emerging financial markets.

Scaling and volatility of breakouts and breakdowns in stock price dynamics.

Directory of Open Access Journals (Sweden)

Lu Liu

Full Text Available BACKGROUND: Because the movement of stock prices is not only ubiquitous in financial markets but also crucial for investors, extensive studies have been done to understand the law behind it. In particular, since the financial crisis in 2008, researchers have a more interest in investigating large market volatilities in order to grasp changing market trends. METHODOLOGY/PRINCIPAL FINDINGS: In this work, we analyze the breakouts and breakdowns of both the Standard & Poor's 500 Index in the US stock market and the Shanghai Composite Index in the Chinese stock market. The breakout usually represents an ongoing upward trend in technical analysis while the breakdown represents an ongoing downward trend. Based on the renormalization method, we introduce two parameters to quantize breakouts and breakdowns, respectively. We discover scaling behavior, characterized by power-law distributions for both the breakouts and breakdowns in the two financial markets with different power-law exponents, which reflect different market volatilities. In detail, the market volatility for breakdowns is usually larger than that for breakouts. Moreover, as an emerging market, the Chinese stock market has larger market volatilities for both the breakouts and breakdowns than the US stock market (a mature market. Further, the short-term volatilities show similar features for both the US stock market and the Chinese stock market. However, the medium-term volatilities in the US stock market are almost symmetrical for the breakouts and breakdowns, whereas those in the Chinese stock market appear to be asymmetrical for the breakouts and breakdowns. CONCLUSIONS/SIGNIFICANCE: The methodology presented here provides a way to understand scaling and hence volatilities of breakouts and breakdowns in stock price dynamics. Our findings not only reveal the features of market volatilities but also make a comparison between mature and emerging financial markets.

Low-pressure gas breakdown in longitudinal combined electric fields

International Nuclear Information System (INIS)

Lisovskiy, V A; Kharchenko, N D; Yegorenkov, V D

2010-01-01

This paper contains the complete experimental and analytical picture of gas breakdown in combined electric fields for arbitrary values of rf and dc fields. To obtain it, we continued the study of the discharge ignition modes in nitrogen with simultaneous application of dc and rf electric fields presented in Lisovskiy et al (2008 J. Phys. D: Appl. Phys. 41 125207). To this end, we studied the effect of rf voltage on dc discharge ignition. When we applied an rf voltage exceeding the one corresponding to the minimum breakdown voltage of a self-sustained rf discharge, the curve of dependence of the dc breakdown voltage of a combined discharge on gas pressure was found to consist of two sections. We got the generalized gas breakdown criterion in the combined field valid for arbitrary values of rf and dc electric fields. The calculation results agree with experimental data satisfactorily.

The validity of the general similarity law for electrical breakdown of gases

International Nuclear Information System (INIS)

Osmokrovic, Predrag; Zivic, Tamara; Loncar, Boris; Vasic, Aleksandra

2006-01-01

This paper investigates the validity of the similarity law in cases of dc and pulse breakdown of gases. Geometrically similar systems insulated with SF 6 gas were used during experiments. It is shown that the similarity law is valid for dc breakdown voltage if the electron mean free path is included in geometrical parameters of the system, but not for pulse breakdown voltages. The explanation for this is the mechanism of the pulse discharge. The similarity law was expanded to take into account mechanisms of pulse breakdown initiation. Thus, the general similarity law is obtained, the validity of which in case of a pulse breakdown is established experimentally

Modulating fracture properties of mixed protein systems

NARCIS (Netherlands)

Ersch, C.E.; Laak, I. ter; Linden, E. van der; Venema, P.; Martin, A.H.

2015-01-01

To design foods with desired textures it is important to understand structure build-up and breakdown. One can obtain a wide range of structures using mixtures of different structuring ingredients such as for example protein mixtures. Mixed soy protein isolate (SPI)/gelatine gels were analyzed for

Breakdown Breakthrough: NREL Finds Easier Ways to Deconstruct Biomass |

Science.gov (United States)

News | NREL Breakdown Breakthrough: NREL Finds Easier Ways to Deconstruct Biomass Breakdown Breakthrough: NREL Finds Easier Ways to Deconstruct Biomass May 22, 2018 Roman Brunecky (left), Yannick Bomble soften biomass. Photo by Dennis Schroeder, NREL If there's an easier, more efficient method, science will

Existence of life-time stable proteins in mature rats-Dating of proteins' age by repeated short-term exposure to labeled amino acids throughout age

DEFF Research Database (Denmark)

Bechshøft, Cecilie Leidesdorff; Schjerling, Peter; Bornø, Andreas

2017-01-01

In vivo turnover rates of proteins covering the processes of protein synthesis and breakdown rates have been measured in many tissues and protein pools using various techniques. Connective tissue and collagen protein turnover is of specific interest since existing results are rather diverging. Th...... living days, indicating very slow turnover. The data support the hypothesis that some proteins synthesized during the early development and growth still exist much later in life of animals and hence has a very slow turnover rate.......In vivo turnover rates of proteins covering the processes of protein synthesis and breakdown rates have been measured in many tissues and protein pools using various techniques. Connective tissue and collagen protein turnover is of specific interest since existing results are rather diverging....... The aim of this study is to investigate whether we can verify the presence of protein pools within the same tissue with very distinct turnover rates over the life-span of rats with special focus on connective tissue. Male and female Lewis rats (n = 35) were injected with five different isotopically...

Fear of breakdown and the unlived life.

Science.gov (United States)

Ogden, Thomas H

2014-04-01

Winnicott's Fear of breakdown is an unfinished work that requires that the reader be not only a reader, but also a writer of this work which often gestures toward meaning as opposed to presenting fully developed ideas. The author's understanding of the often confusing, sometimes opaque, argument of Winnicott's paper is as follows. In infancy there occurs a breakdown in the mother-infant tie that forces the infant to take on, by himself, emotional events that he is unable to manage. He short-circuits his experience of primitive agony by generating defense organizations that are psychotic in nature, i.e., they substitute self-created inner reality for external reality, thus foreclosing his actually experiencing critical life events. By not experiencing the breakdown of the mother-infant tie when it occurred in infancy, the individual creates a psychological state in which he lives in fear of a breakdown that has already happened, but which he did not experience. The author extends Winnicott's thinking by suggesting that the driving force of the patient's need to find the source of his fear is his feeling that parts of himself are missing and that he must find them if he is to become whole. What remains of his life feels to him like a life that is mostly an unlived life. Copyright © 2014 Institute of Psychoanalysis.

Reversible post-breakdown conduction in aluminum oxide-polymer capacitors

NARCIS (Netherlands)

Chen, Qian; Gomes, H.L.; Rocha, P.R.F.; Leeuw, de D.M.; Meskers, S.C.J.

2013-01-01

Aluminum/Al2O3/polymer/metal capacitors submitted to a low-power constant current stress undergo dielectric breakdown. The post-breakdown conduction is metastable, and over time the capacitors recover their original insulating properties. The decay of the conduction with time follows a power law

Vortex breakdown in closed containers with polygonal cross sections

International Nuclear Information System (INIS)

Naumov, I. V.; Dvoynishnikov, S. V.; Kabardin, I. K.; Tsoy, M. A.

2015-01-01

The vortex breakdown bubble in the confined flow generated by a rotating lid in closed containers with polygonal cross sections was analysed both experimentally and numerically for the height/radius aspect ratio equal to 2. The stagnation point locations of the breakdown bubble emergence and the corresponding Reynolds number were determined experimentally and in addition computed numerically by STAR-CCM+ CFD software for square, pentagonal, hexagonal, and octagonal cross section configurations. The flow pattern and the velocity were observed and measured by combining the seeding particle visualization and the temporal accuracy of laser Doppler anemometry. The vortex breakdown size and position on the container axis were determined for Reynolds numbers, ranging from 1450 to 2400. The obtained results were compared with the flow structure in the closed container of cubical and cylindrical configurations. It is shown that the measured evolution of steady vortex breakdown is in close agreement with the numerical results

Prediction of vortex breakdown on a delta wing

Science.gov (United States)

Agrawal, S.; Robinson, B. A.; Barnett, R. M.

1992-01-01

Recent studies of leading-edge vortex flows with computational fluid dynamics codes using Euler or Navier-Stokes formulations have shown fair agreement with experimental data. These studies have concentrated on simulating the flowfields associated with a sharp-edged flat plate 70 deg delta wing at angles of attack where vortex breakdown or burst is observed over the wing. There are, however, a number of discrepancies between the experimental data and the computed flowfields. The location of vortex breakdown in the computational solutions is seen to differ from the experimental data and to vary with changes in the computational grid and freestream Mach number. There also remain issues as to the validity of steady-state computations for cases which contain regions of unsteady flow, such as in the post-breakdown regions. As a partial response to these questions, a number of laminar Navier-Stokes solutions were examined for the 70 deg delta wing. The computed solutions are compared with an experimental database obtained at low subsonic speeds. The convergence of forces, moments and vortex breakdown locations are also analyzed to determine if the computed flowfields actually reach steady-state conditions.

A Drosophila model of dominant inclusion body myopathy type 3 shows diminished myosin kinetics that reduce muscle power and yield myofibrillar defects.

Science.gov (United States)

Suggs, Jennifer A; Melkani, Girish C; Glasheen, Bernadette M; Detor, Mia M; Melkani, Anju; Marsan, Nathan P; Swank, Douglas M; Bernstein, Sanford I

2017-06-01

Individuals with inclusion body myopathy type 3 (IBM3) display congenital joint contractures with early-onset muscle weakness that becomes more severe in adulthood. The disease arises from an autosomal dominant point mutation causing an E706K substitution in myosin heavy chain type IIa. We have previously expressed the corresponding myosin mutation (E701K) in homozygous Drosophila indirect flight muscles and recapitulated the myofibrillar degeneration and inclusion bodies observed in the human disease. We have also found that purified E701K myosin has dramatically reduced actin-sliding velocity and ATPase levels. Since IBM3 is a dominant condition, we now examine the disease state in heterozygote Drosophila in order to gain a mechanistic understanding of E701K pathogenicity. Myosin ATPase activities in heterozygotes suggest that approximately equimolar levels of myosin accumulate from each allele. In vitro actin sliding velocity rates for myosin isolated from the heterozygotes were lower than the control, but higher than for the pure mutant isoform. Although sarcomeric ultrastructure was nearly wild type in young adults, mechanical analysis of skinned indirect flight muscle fibers revealed a 59% decrease in maximum oscillatory power generation and an approximately 20% reduction in the frequency at which maximum power was produced. Rate constant analyses suggest a decrease in the rate of myosin attachment to actin, with myosin spending decreased time in the strongly bound state. These mechanical alterations result in a one-third decrease in wing beat frequency and marginal flight ability. With aging, muscle ultrastructure and function progressively declined. Aged myofibrils showed Z-line streaming, consistent with the human heterozygote phenotype. Based upon the mechanical studies, we hypothesize that the mutation decreases the probability of the power stroke occurring and/or alters the degree of movement of the myosin lever arm, resulting in decreased in vitro

A Drosophila model of dominant inclusion body myopathy type 3 shows diminished myosin kinetics that reduce muscle power and yield myofibrillar defects

Directory of Open Access Journals (Sweden)

Jennifer A. Suggs

2017-06-01

Full Text Available Individuals with inclusion body myopathy type 3 (IBM3 display congenital joint contractures with early-onset muscle weakness that becomes more severe in adulthood. The disease arises from an autosomal dominant point mutation causing an E706K substitution in myosin heavy chain type IIa. We have previously expressed the corresponding myosin mutation (E701K in homozygous Drosophila indirect flight muscles and recapitulated the myofibrillar degeneration and inclusion bodies observed in the human disease. We have also found that purified E701K myosin has dramatically reduced actin-sliding velocity and ATPase levels. Since IBM3 is a dominant condition, we now examine the disease state in heterozygote Drosophila in order to gain a mechanistic understanding of E701K pathogenicity. Myosin ATPase activities in heterozygotes suggest that approximately equimolar levels of myosin accumulate from each allele. In vitro actin sliding velocity rates for myosin isolated from the heterozygotes were lower than the control, but higher than for the pure mutant isoform. Although sarcomeric ultrastructure was nearly wild type in young adults, mechanical analysis of skinned indirect flight muscle fibers revealed a 59% decrease in maximum oscillatory power generation and an approximately 20% reduction in the frequency at which maximum power was produced. Rate constant analyses suggest a decrease in the rate of myosin attachment to actin, with myosin spending decreased time in the strongly bound state. These mechanical alterations result in a one-third decrease in wing beat frequency and marginal flight ability. With aging, muscle ultrastructure and function progressively declined. Aged myofibrils showed Z-line streaming, consistent with the human heterozygote phenotype. Based upon the mechanical studies, we hypothesize that the mutation decreases the probability of the power stroke occurring and/or alters the degree of movement of the myosin lever arm, resulting in

Abnormal breakdown characteristic in a two-phase mixture

International Nuclear Information System (INIS)

Ye Qizheng; Li Jin; Lu Fei

2006-01-01

A two-phase mixture (TPM) is a mixture of gas and macroparticles of high concentration. Based on Townsend's theory, a new cell-iterative model in analytical form for the breakdown mechanism in TPM is presented. Compared with the original cell-iterative model in our previous paper, the obstructive factor of the macroparticles that influences the electron avalanche propagation is considered, except for the macroparticles distorting the electrical field and capture of the electrons. The cell attractive parameter k is presented according to the classical continuum theory for field charging. The modified Paschen law for a TPM is presented to calculate the breakdown voltage. The breakdown voltage of the TPM, U TPM , increases gradually with an increase in the macroparticle number density (m). The voltage U TPM is lower than that of the pure gas at low m values and larger at high m values. With a decrease of the macroparticle volume fraction and the dielectric mismatch, the voltage U TPM increases gradually at low m values and decreases gradually at high m values. The voltage U TPM at pd 200 cm Torr is lower than that at pd = 760 cm Torr for low m values and larger for high m values. This kind of abnormal breakdown characteristic in the TPM occurs in the case of high macroparticle volume fraction. On the other hand, the minimum of the TPM's Paschen curve increases with increase in m. It provides the possibility and the conditions of greatly increasing the breakdown voltage in a nearly uniform field

Abnormal breakdown characteristic in a two-phase mixture

Energy Technology Data Exchange (ETDEWEB)

Ye Qizheng; Li Jin; Lu Fei [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China)

2006-05-21

A two-phase mixture (TPM) is a mixture of gas and macroparticles of high concentration. Based on Townsend's theory, a new cell-iterative model in analytical form for the breakdown mechanism in TPM is presented. Compared with the original cell-iterative model in our previous paper, the obstructive factor of the macroparticles that influences the electron avalanche propagation is considered, except for the macroparticles distorting the electrical field and capture of the electrons. The cell attractive parameter k is presented according to the classical continuum theory for field charging. The modified Paschen law for a TPM is presented to calculate the breakdown voltage. The breakdown voltage of the TPM, U{sub TPM}, increases gradually with an increase in the macroparticle number density (m). The voltage U{sub TPM} is lower than that of the pure gas at low m values and larger at high m values. With a decrease of the macroparticle volume fraction and the dielectric mismatch, the voltage U{sub TPM} increases gradually at low m values and decreases gradually at high m values. The voltage U{sub TPM} at pd 200 cm Torr is lower than that at pd = 760 cm Torr for low m values and larger for high m values. This kind of abnormal breakdown characteristic in the TPM occurs in the case of high macroparticle volume fraction. On the other hand, the minimum of the TPM's Paschen curve increases with increase in m. It provides the possibility and the conditions of greatly increasing the breakdown voltage in a nearly uniform field.

NASA Work Breakdown Structure (WBS) Handbook

Science.gov (United States)

Terrell, Stefanie M.

2018-01-01

The purpose of this document is to provide program/project teams necessary instruction and guidance in the best practices for Work Breakdown Structure (WBS) and WBS dictionary development and use for project implementation and management control. This handbook can be used for all types of NASA projects and work activities including research, development, construction, test and evaluation, and operations. The products of these work efforts may be hardware, software, data, or service elements (alone or in combination). The aim of this document is to assist project teams in the development of effective work breakdown structures that provide a framework of common reference for all project elements.

Statistics of vacuum breakdown in the high-gradient and low-rate regime

Science.gov (United States)

Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio; Korsbäck, Anders; Djurabekova, Flyura; Rajamäki, Robin; Giner-Navarro, Jorge

2017-01-01

In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

Moisture migration, microstructure damage and protein structure changes in porcine longissimus muscle as influenced by multiple freeze-thaw cycles.

Science.gov (United States)

Zhang, Mingcheng; Li, Fangfei; Diao, Xinping; Kong, Baohua; Xia, Xiufang

2017-11-01

This study investigated the effects of multiple freeze-thaw (F-T) cycles on water mobility, microstructure damage and protein structure changes in porcine longissimus muscle. The transverse relaxation time T 2 increased significantly when muscles were subjected to multiple F-T cycles (Pcycles caused sarcomere shortening, Z line fractures, and I band weakening and also led to microstructural destruction of muscle tissue. The decreased free amino group content and increased dityrosine in myofibrillar protein (MP) revealed that multiple F-T cycles caused protein cross-linking and oxidation. In addition, the results of size exclusion chromatography, circular dichroism spectra, UV absorption spectra, and intrinsic fluorescence spectroscopy indirectly proved that multiple F-T cycles could cause protein aggregation and degradation, α-helix structure disruption, hydrophobic domain exposure, and conformational changes of MP. Overall, repeated F-T cycles changed the protein structure and water distribution within meat. Copyright © 2017 Elsevier Ltd. All rights reserved.

The influence of the tensile stress on magnetic breakdown in niobium

International Nuclear Information System (INIS)

Alekseevskii, N.E.; Glinski, M.; Nizhankovskii, V.I.

1980-01-01

It has been shown that magnetic breakdown takes place through the spin-orbital gaps between the hole octahedron of the second Brillouin zone and the open multiply connected surface of hole of the third zone, in two junctions. It is expected that even a small deformation of the sample, lowering the lattice symmetry should eliminate the magnetic breakdown by symmetry point contacts and should change the spectrum of the magnetic breakdown thermopower oscillations. Therefore, the influence of the uniaxial tensile stress on magnetic breakdown was investigated. Experimental details and results are given. The results indicate the change of the spin-orbit gap caused by stress is most probably anisotropic. (U.K.)

Breakdowns in Coordination Between Air Traffic Controllers

Science.gov (United States)

Bearman, Chris; Orasanu, Judith; Miller, Ronald C.

2011-01-01

This talk outlines the complexity of coordination in air traffic control, introduces the NextGen technologies, identifies common causes for coordination breakdowns in air traffic control and examines whether these causes are likely to be reduced with the introduction of NextGen technologies. While some of the common causes of breakdowns will be reduced in a NextGen environment this conclusion should be drawn carefully given the current stage of development of the technologies and the observation that new technologies often shift problems rather than reduce them.

The rate of dielectric breakdown weathering of lunar regolith in permanently shadowed regions

Science.gov (United States)

Jordan, A. P.; Stubbs, T. J.; Wilson, J. K.; Schwadron, N. A.; Spence, H. E.

2017-02-01

Large solar energetic particle events may cause dielectric breakdown in the upper 1 mm of regolith in permanently shadowed regions (PSRs). We estimate how the resulting breakdown weathering compares to meteoroid impact weathering. Although the SEP event rates measured by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO) are too low for breakdown to have significantly affected the regolith over the duration of the LRO mission, regolith gardened by meteoroid impacts has been exposed to SEPs for ∼106 yr. Therefore, we estimate that breakdown weathering's production rate of vapor and melt in the coldest PSRs is up to 1.8 - 3.5 ×10-7 kg m-2 yr-1 , which is comparable to that produced by meteoroid impacts. Thus, in PSRs, up to 10-25% of the regolith may have been melted or vaporized by dielectric breakdown. Breakdown weathering could also be consistent with observations of the increased porosity ("fairy castles") of PSR regolith. We also show that it is conceivable that breakdown-weathered material is present in Apollo soil samples. Consequently, breakdown weathering could be an important process within PSRs, and it warrants further investigation.

Accoustic Localization of Breakdown in Radio Frequency Accelerating Cavities

Energy Technology Data Exchange (ETDEWEB)

Lane, Peter Gwin [IIT, Chicago

2016-07-01

Current designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. In this context and in general, the use of RF cavities in strong magnetic fields has its challenges. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to small regions of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Details on RF cavity sound sources as well as the hardware, software, and algorithms used to localize the source of sound emitted from breakdown thermal shocks are presented. In addition, results from simulations and experiments on three RF cavities, namely the Aluminum Mock Cavity, the High-Pressure Cavity, and the Modular Cavity, are also given. These results demonstrate the validity and effectiveness of the described technique for acoustic localization of breakdown.

Communication Breakdown: Unraveling the Islamic States Media Efforts

Science.gov (United States)

2016-10-01

Communication Breakdown: Unraveling the Islamic State’s Media Efforts Daniel Milton Communication Breakdown: Unraveling the Islamic State’s Media ...production arm of central media office).28 The high level of communication between the central media office and the satellite offices illustrates the tension...and discussed by the mass media . Those products are likely important to the group’s recruitment efforts, but clearly it is trying to portray itself

Variables associated with family breakdown in healthy and obese/ overweigh adolescents

Directory of Open Access Journals (Sweden)

Carla Cristina J. N. de Almeida

2014-03-01

Full Text Available Objective: To evaluate the presence of family breakdown factors among eutrophic and overweight/obese adolescents. Methods: Cross-sectional study of 242 students aged between 14 and 19 years old, from a public school. Each student was weighed, measured and answered a questionnaire with closed questions addressing the presence of family breakdown factors. The adolescents were divided in two groups: euthophic and overweight/obese. The answers of both groups were compared by Fisher's exact and Mann-Whitney tests. Results: There was no statistically significant difference in the prevalence of the studied factors between the two groups. Comparing the number of positive answers (presence of family breakdown factors and negative ones (absence of family breakdown factors, no difference was observed between the groups. Conclusions: The inclusion of a control group showed that factors of family breakdown, usually identified as associated with obesity in adolescents, may also be present in eutrophic adolescents.

DC breakdown characteristics of silicone polymer composites for HVDC insulator applications

Science.gov (United States)

Han, Byung-Jo; Seo, In-Jin; Seong, Jae-Kyu; Hwang, Young-Ho; Yang, Hai-Won

2015-11-01

Critical components for HVDC transmission systems are polymer insulators, which have stricter requirements that are more difficult to achieve compared to those of HVAC insulators. In this study, we investigated the optimal design of HVDC polymer insulators by using a DC electric field analysis and experiments. The physical properties of the polymer specimens were analyzed to develop an optimal HVDC polymer material, and four polymer specimens were prepared for DC breakdown experiments. Single and reverse polarity breakdown tests were conducted to analyze the effect of temperature on the breakdown strength of the polymer. In addition, electric fields were analyzed via simulations, in which a small-scale polymer insulator model was applied to prevent dielectric breakdown due to electric field concentration, with four DC operating conditions taken into consideration. The experimental results show that the electrical breakdown strength and the electric field distribution exhibit significant differences in relation to different DC polarity transition procedures.

Statistics of vacuum breakdown in the high-gradient and low-rate regime

Directory of Open Access Journals (Sweden)

Walter Wuensch

2017-01-01

Full Text Available In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

PHENIX Work Breakdown Structure

International Nuclear Information System (INIS)

1994-02-01

The Work Breakdown Structure (WBS) Book begins with this Overview section, which contains the high-level summary cost estimate, the cost profile, and the global construction schedule. The summary cost estimate shows the total US cost and the cost in terms of PHENIX construction funds for building the PHENIX detector. All costs in the WBS book are shown in FY 1993 dollars. Also shown are the institutional and foreign contributions, the level of pre-operations funding, and the cost of deferred items. Pie charts are presented at PHENIX WBS level 1 and 2 that show this information. The PHENIX construction funds are shown broken down to PHENIX WBS level 3 items per fiscal year, and the resulting profile is compared to the RHIC target profile. An accumulated difference of the two profiles is also shown. The PHENIX global construction schedule is presented at the end of the Overview section. Following the Overview are sections for each subsystem. Each subsystem section begins with a summary cost estimate, cost profile, and critical path. The total level 3 cost is broken down into fixed costs (M ampersand S), engineering costs (EDIA) and labor costs. Costs are further broken down in terms of PHENIX construction funds, institutional and foreign contributions, pre-operations funding, and deferred items. Also shown is the contingency at level 3 and the level 4 breakdown of the total cost. The cost profile in fiscal years is shown at level 3. The subsystem summaries are followed by the full cost estimate and schedule sheets for that subsystem. These detailed sheets are typically carried down to level 7 or 8. The cost estimate shows Total, M ampersand S, EDIA, and Labor breakdowns, as well as contingency, for each WBS entry

Impulse breakdown of small air gap in electric field Part II: Statistical ...

African Journals Online (AJOL)

The patterns of shot distribution and maximum coverage at impulse breakdown voltage for positive point electr-odes (needle and cone electrodes) in small air gaps in non-uniform electric fields were investigated. During the breakdown test, a sheet of paper was placed on the plate electrode (-ve), and each breakdown shot ...

RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES

Energy Technology Data Exchange (ETDEWEB)

Johnson, Rolland

2014-09-21

Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Part of the problem is that RF breakdown in an evacuated cavity involves a complex mixture of effects, which include the geometry, metallurgy, and surface preparation of the accelerating structures and the make-up and pressure of the residual gas in which plasmas form. Studies showed that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas, as needed for muon cooling channels, without the need for long conditioning times, even in the presence of strong external magnetic fields. This positive result was expected because the dense gas can practically eliminate dark currents and multipacting. In this project we used this high pressure technique to suppress effects of residual vacuum and geometry that are found in evacuated cavities in order to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. One of the interesting and useful outcomes of this project was the unanticipated collaborations with LANL and Fermilab that led to new insights as to the operation of evacuated normal-conducting RF cavities in high external magnetic fields. Other accomplishments included: (1) RF breakdown experiments to test the effects of SF6 dopant in H2 and He gases with Sn, Al, and Cu electrodes were carried out in an 805 MHz cavity and compared to calculations and computer simulations. The heavy corrosion caused by the SF6 components led to the suggestion that a small admixture of oxygen, instead of SF6, to the hydrogen would allow the same advantages without the corrosion in a practical muon beam line. (2) A

Localization of rf breakdowns in a standing wave cavity

Directory of Open Access Journals (Sweden)

Faya Wang

2009-04-01

Full Text Available At SLAC, a five-cell, normal-conducting, L-band (1.3 GHz, standing-wave (SW cavity was built as a prototype positron capture accelerator for the ILC. The structure met the ILC gradient goal but required extensive rf processing. When rf breakdowns occurred, a large variation was observed in the decay rate of the stored energy in the cavity after the input power was shut off. It appeared that the breakdowns were isolating sections of the cavity, and that the trapped energy in those sections was then partitioned among its natural modes, producing a distinct beating pattern during the decay. To explore this phenomenon further, an equivalent circuit model of cavity was created that reproduces well its normal operating characteristics. The model was then used to compute the spectra of trapped energy for different numbers of isolated cells. The resulting modal patterns agree well with those of the breakdown data, and thus such a comparison appears to provide a means of identifying the irises on which the breakdowns occurred.

On correction factor in scaling law for low pressure DC gas breakdown

International Nuclear Information System (INIS)

Gleb Wataghin, UNICAMP, Campinas, SP (Brazil))" data-affiliation=" (Instituto de Física Gleb Wataghin, UNICAMP, Campinas, SP (Brazil))" >Ronchi, G; Gleb Wataghin, UNICAMP, Campinas, SP (Brazil))" data-affiliation=" (Instituto de Física Gleb Wataghin, UNICAMP, Campinas, SP (Brazil))" >Machida, M

2014-01-01

The low pressure gas breakdown described by Paschen's law in Townsend theory, i.e. the breakdown voltage as a function of gas pressure p and the electrode distance d, provides an accurate description of breakdown in DC discharges when the ratio between inter-electrode gap distance d and electrode radii R tends to zero. On increasing of the ratio d/R, the Paschen's curves are shifted to the region of higher breakdown voltage and higher pd values. A modified Paschen's law recently proposed is well satisfied in our measurements. However, the value of constant b changes not only due to gas type but also according to electrode gap distance; furthermore, gas breakdown voltages are considerably modified by plasma-wall interactions due to glass tube proximity in the discharge.

Electrical breakdown studies with Mycalex insulators

International Nuclear Information System (INIS)

Waldron, W.; Greenway, W.; Eylon, S.; Henestroza, E.; Yu, S.

2003-01-01

Insulating materials such as alumina and glass-bonded mica (Mycalex) are used in accelerator systems for high voltage feedthroughs, structural supports, and barriers between high voltage insulating oil and the vacuum beam pipe in induction accelerator cells. Electric fields in the triple points should be minimized to prevent voltage breakdown. Mechanical stress can compromise seals and result in oil contamination of the insulator surface. We have tested various insulator cleaning procedures including ultrasonic cleaning with a variety of aqueous-based detergents, and manual scrubbing with various detergents. Water sheeting tests were used to determine the initial results of the cleaning methods. Ultimately, voltage breakdown tests will be used to quantify the benefits of these cleaning procedures

Lowering effect of radioactive irradiation on breakdown voltage and electron avalanche pulse characteristics

International Nuclear Information System (INIS)

Kawahashi, Akira; Nakano, Toru; Hosokawa, Tatsuzo; Miyoshi, Yosinori.

1976-01-01

In the time resolving measurement of the growing process and breakdown of electron avalanche in a gap of uniform electric field, the phenomenon that DC breakdown voltage slightly lowered was observed when β ray was irradiated as the initial electron source, as compared with unirradiated condition. Beta source used is 90 Sr- 90 Y of 2 mCi in radiative equilibrium. The experimental results and the examination are described in detail. In brief, the remarkable superposition of succeeding avalanche pulse over the preceeding avalanche pulse waveform was observed under the gap condition in which the breakdown voltage decreased in β-ray irradiation. Thus this superposition of avalanche pulses is considered as one of the causes of the breakdown voltage reduction. When β source is used as the initial electron source, the number of supplied initial electrons is very large as compared with unity, and at the same time, a great number of initial electrons can be supplied within the diffusion radius r of avalanche. Then the effect of initial electron number n 0 was considered by employing a diagram for breakdown scheme. The transition from Townsend type breakdown to streamer type breakdown occurs owing to increasing n 0 , and in that condition, the breakdown voltage lowers slightly. (Wakatsuki, Y)

Gas breakdown at cyclotron resonance with a submillimeter laser

International Nuclear Information System (INIS)

Hacker, M.P.; Temkin, R.J.; Lax, B.

1976-01-01

A pulsed 496-μm CH 3 F laser is used to produce gas breakdown in He at pressures between 1 and 300 Torr in an intense longitudinal magnetic field. Breakdown is detected by the observation of visible light when the electron cyclotron frequency (eB/m) equals the laser frequency, which occurs at B=216 kG for lambda=496 μm. At the lowest helium pressures and near cyclotron resonance, the focused laser intensity of 40 kW/cm 2 gives rise to very large electron heating rates, well beyond the limit of validity of conventional equilibrium breakdown theory. The observed result is an intensity-dependent resonant linewidth, much larger than predicted by equilibrium theories

High-gradient breakdown studies of an X-band Compact Linear Collider prototype structure

Directory of Open Access Journals (Sweden)

Xiaowei Wu

2017-05-01

Full Text Available A Compact Linear Collider prototype traveling-wave accelerator structure fabricated at Tsinghua University was recently high-gradient tested at the High Energy Accelerator Research Organization (KEK. This X-band structure showed good high-gradient performance of up to 100  MV/m and obtained a breakdown rate of 1.27×10^{−8} per pulse per meter at a pulse length of 250 ns. This performance was similar to that of previous structures tested at KEK and the test facility at the European Organization for Nuclear Research (CERN, thereby validating the assembly and bonding of the fabricated structure. Phenomena related to vacuum breakdown were investigated and are discussed in the present study. Evaluation of the breakdown timing revealed a special type of breakdown occurring in the immediately succeeding pulse after a usual breakdown. These breakdowns tended to occur at the beginning of the rf pulse, whereas usual breakdowns were uniformly distributed in the rf pulse. The high-gradient test was conducted under the international collaboration research program among Tsinghua University, CERN, and KEK.

Influence of temperature on current-induced domain wall motion and its Walker breakdown

International Nuclear Information System (INIS)

Fan, Lvchao; Hu, Jingguo; Su, Yuanchang; Zhu, Jinrong

2016-01-01

The current-driven domain wall propagation along a thin ferromagnetic strip with thermal field is studied by means of micromagnetic simulations. The results show that the velocity of domain wall is almost independent of temperature until Walker breakdown happened. However the thermal field can suppress Walker breakdown and makes domain wall move faster. Further analysis indicates that the thermal field tends to keep the out-of-plane magnetic moment of the domain wall stay in high value, which can promote domain wall motion and suppress the Walker breakdown by breaking the period of domain wall transformation. - Highlights: • Influences of temperature on the displacement and the velocity of DW are shown. • The suppression of Walker breakdown by temperature is given. • The reason for suppressing Walker breakdown is analyzed. • The breaking transformation period of Walker breakdown by temperature is given.

Ionizing potential waves and high-voltage breakdown streamers.

Science.gov (United States)

Albright, N. W.; Tidman, D. A.

1972-01-01

The structure of ionizing potential waves driven by a strong electric field in a dense gas is discussed. Negative breakdown waves are found to propagate with a velocity proportional to the electric field normal to the wavefront. This causes a curved ionizing potential wavefront to focus down into a filamentary structure, and may provide the reason why breakdown in dense gases propagates in the form of a narrow leader streamer instead of a broad wavefront.

The breakdown and glow phases during the initiation of discharges for lamps

International Nuclear Information System (INIS)

Pitchford, L.C.; Peres, I.; Liland, K.B.; Boeuf, J.P.; Gielen, H.

1997-01-01

High intensity discharge (HID) lamps are often initiated by the application of one or more short, high-voltage, breakdown pulses superimposed on a 50 or 60 Hz generator voltage. A successful transition from the breakdown event to steady-state operating conditions in HID lamps requires that the lamp-circuit system be adequate to sustain the plasma created during breakdown until the electrodes are heated to thermionic temperatures. In this article, we use a one-dimensional (in the axial direction) transient discharge model to study the conditions needed to sustain the cold-cathode discharge after a breakdown event has occurred. While the application of our one-dimensional model to real lamps is approximate, we find that the model predictions are consistent with experimental results in HID lamps, a few of which are presented here. The main conclusion from this work is that, after breakdown, the voltage necessary to sustain a glow discharge is dependent on the source impedance, the gas composition, and on the plasma density created by the breakdown event. copyright 1997 American Institute of Physics

Breakdown in the organ donation process and its effect on organ availability.

Science.gov (United States)

Razdan, Manik; Degenholtz, Howard B; Kahn, Jeremy M; Driessen, Julia

2015-01-01

Background. This study examines the effect of breakdown in the organ donation process on the availability of transplantable organs. A process breakdown is defined as a deviation from the organ donation protocol that may jeopardize organ recovery. Methods. A retrospective analysis of donation-eligible decedents was conducted using data from an independent organ procurement organization. Adjusted effect of process breakdown on organs transplanted from an eligible decedent was examined using multivariable zero-inflated Poisson regression. Results. An eligible decedent is four times more likely to become an organ donor when there is no process breakdown (adjusted OR: 4.01; 95% CI: 1.6838, 9.6414; P organs yielded. Overall, for every process breakdown occurring in the care of an eligible decedent, one less organ is available for transplant. Decedent's age is a strong predictor of likelihood of donation and the number of organs transplanted from a donor. Conclusion. Eliminating breakdowns in the donation process can potentially increase the number of organs available for transplant but some organs will still be lost.

Junction depth dependence of breakdown in silicon detector diodes

International Nuclear Information System (INIS)

Beck, G.A.; Carter, A.A.; Carter, J.R.; Greenwood, N.M.; Lucas, A.D.; Munday, D.J.; Pritchard, T.W.; Robinson, D.; Wilburn, C.D.; Wyllie, K.

1996-01-01

The high voltage capability of detector diodes fabricated in the planar process is limited by the high field generated at the edge of the junction.We have fabricated diodes with increased junction depth with respect to our standard process and find a significantly higher breakdown voltage,in reasonable agreement with previous studies of junction breakdown. (orig.)

Beauty in the Breakdown

Science.gov (United States)

Brisco, Nicole

2008-01-01

Most human beings look at erosion as the destruction of a surface, but artists can see that erosion often creates indefinable beauty. Where do you see beauty in the breakdown? In this article, the author presents an innovative lesson that would allow students to observe both human and physical nature. In this activity students will create a work…

Breakdown localization in the fixed gap system

CERN Document Server

Rajamaki, Robin; Wuensch, Walter

2014-01-01

Accurate localization of breakdowns in vacuum could help shed light on breakdown related processes that are not yet fully understood. At the DC spark lab at CERN, an instrument called the Fixed Gap System (FGS) has been developed partially for this purpose. Among other things, the FGS has four built-in antennas, which are intended for breakdown localization. The capability of this aspect of the FGS was explored in this report. Specifically, the feasibility of using a method similar to that which is used in cavity Beam Position Monitors (BPMs) was investigated. The usable frequency range of the current experimental setup was also studied. Firstly, a modal analysis of the inner geometry of the FGS was done in HFSS. This showed that the two first modes to be expected in the spark gap quite differ from those of the ideal pillbox – both in field pattern and in frequency ( 4 and 6 GHz vs. 0.2 and 3 GHz). Secondly, S-parameters of the system were measured. These showed that the coupling between antennas is weak...

Protein intake does not increase vastus lateralis muscle protein synthesis during cycling

DEFF Research Database (Denmark)

Hulston, CJ; Wolsk, Emil; Grøndahl, Thomas Sahl

2011-01-01

PURPOSE: This study aimed to investigate the effect of protein ingestion on leg protein turnover and vastus lateralis muscle protein synthesis during bicycle exercise and recovery. METHODS: Eight healthy males participated in two experiments in which they ingested either a carbohydrate solution...... sampling, and blood flow measurements. Muscle protein synthesis was calculated from the incorporation of l-[ring-C6]phenylalanine into protein. RESULTS: Consuming protein during exercise increased leg protein synthesis and decreased net leg protein breakdown; however, protein ingestion did not increase...... protein synthesis within the highly active vastus lateralis muscle (0.029%·h(-1), ± 0.004%·h(-1), and 0.030%·h(-1), ± 0.003%·h(-1), in CHO and CHO + P, respectively; P = 0.88). In contrast, consuming protein, during exercise and recovery, increased postexercise vastus lateralis muscle protein synthesis...

Noise Parameter Analysis of SiGe HBTs for Different Sizes in the Breakdown Region

Directory of Open Access Journals (Sweden)

Chie-In Lee

2016-01-01

Full Text Available Noise parameters of silicon germanium (SiGe heterojunction bipolar transistors (HBTs for different sizes are investigated in the breakdown region for the first time. When the emitter length of SiGe HBTs shortens, minimum noise figure at breakdown decreases. In addition, narrower emitter width also decreases noise figure of SiGe HBTs in the avalanche region. Reduction of noise performance for smaller emitter length and width of SiGe HBTs at breakdown resulted from the lower noise spectral density resulting from the breakdown mechanism. Good agreement between experimental and simulated noise performance at breakdown is achieved for different sized SiGe HBTs. The presented analysis can benefit the RF circuits operating in the breakdown region.

Predictors of muscle protein synthesis after severe pediatric burns

Science.gov (United States)

Objectives: Following a major burn, muscle protein synthesis rate increases but in most patients, this response is not sufficient to compensate the also elevated protein breakdown. Given the long-term nature of the pathophysiologic response to burn injury, we hypothesized that skeletal muscle prot...

Patients with polymyositis show changes in muscle protein charges

DEFF Research Database (Denmark)

Bartels, E M; Jacobsen, Søren; Rasmussen, L

1989-01-01

Polymyositis (PM) appears with indolent proximal muscle weakness and is an inflammatory disease with breakdown of muscle cells. In our study the protein charge concentrations of the contractile proteins in the A and I bands were determined, applying a microelectrode technique. Patients with PM sh...

Breakdown in the Organ Donation Process and Its Effect on Organ Availability

Directory of Open Access Journals (Sweden)

Manik Razdan

2015-01-01

Full Text Available Background. This study examines the effect of breakdown in the organ donation process on the availability of transplantable organs. A process breakdown is defined as a deviation from the organ donation protocol that may jeopardize organ recovery. Methods. A retrospective analysis of donation-eligible decedents was conducted using data from an independent organ procurement organization. Adjusted effect of process breakdown on organs transplanted from an eligible decedent was examined using multivariable zero-inflated Poisson regression. Results. An eligible decedent is four times more likely to become an organ donor when there is no process breakdown (adjusted OR: 4.01; 95% CI: 1.6838, 9.6414; P<0.01 even after controlling for the decedent’s age, gender, race, and whether or not a decedent had joined the state donor registry. However once the eligible decedent becomes a donor, whether or not there was a process breakdown does not affect the number of transplantable organs yielded. Overall, for every process breakdown occurring in the care of an eligible decedent, one less organ is available for transplant. Decedent’s age is a strong predictor of likelihood of donation and the number of organs transplanted from a donor. Conclusion. Eliminating breakdowns in the donation process can potentially increase the number of organs available for transplant but some organs will still be lost.

A categorization of water system breakdowns: Evidence from Liberia, Nigeria, Tanzania, and Uganda.

Science.gov (United States)

Klug, Tori; Cronk, Ryan; Shields, Katherine F; Bartram, Jamie

2018-04-01

In rural sub-Saharan Africa, one in three handpumps are non-functional at any time. While there is some evidence describing factors associated with non-functional water systems, there is little evidence describing the categories of water system breakdowns that commonly occur. Insufficient water availability from broken down systems can force people to use unimproved water sources, which undermines the health benefits of an improved water source. We categorized common water system breakdowns using quantitative and qualitative monitoring data from Liberia, Nigeria, Tanzania, and Uganda (each N>3600 water systems) and examined how breakdown category varies by water system type and management characteristics. Specific broken parts were mentioned more frequently than all other reasons for breakdown; hardware parts frequently found at fault for breakdown were aprons (Liberia), pipes (Tanzania and Uganda), taps/spouts (Tanzania and Uganda), and lift mechanisms (Nigeria). Statistically significant differences in breakdown category were identified based on system type, age, management type, and fee collection type. Categorization can help to identify common reasons for water system breakdown. The analysis of these data can be used to develop improved monitoring instruments to inform actors of different breakdown types and provide reasons for system non-functionality. Improved monitoring instruments would enable actors to target appropriate resources to address specific breakdowns likely to arise based on system type and management characteristics in order to inform improved implementation of and post-construction support for water systems in sub-Saharan Africa. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancement of dielectric breakdown strengths in polymer film capacitors

International Nuclear Information System (INIS)

Binder, M.; Mammone, R.J.; Lavene, B.; Rondeau, E.

1992-01-01

This paper reports that breakdown voltages of wound, polymer film/metal foil capacitors have been dramatically increased by briefly exposing them (after they had been spirally wound) to a low pressure, low temperature gas plasma. Exposure of wound, polycarbonate-based capacitors to a 96%CF 4 /4%O 2 gas plasma for 4 minutes, for example, produced a 200% increase in breakdown voltage

Influence of pre-cooking protein paste gelation conditions and post-cooking gel storage conditions on gel texture.

Science.gov (United States)

Paker, Ilgin; Matak, Kristen E

2016-01-15

Gelation conditions affect the setting of myofibrillar fish protein gels. Therefore the impact of widely applied pre-cooking gelation time/temperature strategies and post-cooking period on the texture and color of final protein gels was determined. Four pre-cooking gelation strategies (no setting time, 30 min at 25 °C, 1 h at 40 °C or 24 h at 4 °C) were applied to protein pastes (fish protein concentrate and standard functional additives). After cooking, texture and color were analyzed either directly or after 24 h at 4 °C on gels adjusted to 25 °C. No-set gels were harder, gummier and chewier (P cooking. Gel-setting conditions had a greater (P cooking stored gels in texture and color, depending on the pre-cooking gelation strategy. Pre-cooking gelation conditions will affect final protein gel texture and color, with gel stability benefiting from a gel-setting period. However, post-cooking storage may have a greater impact on final gels, with textural attributes becoming more consistent between all samples. © 2015 Society of Chemical Industry.

Breakdown in ZnO Varistors by High Power Electrical Pulses; TOPICAL

International Nuclear Information System (INIS)

PIKE, GORDON E.

2001-01-01

This report documents an investigation of irreversible electrical breakdown in ZnO varistors due to short pulses of high electric field and current density. For those varistors that suffer breakdown, there is a monotonic, pulse-by-pulse degradation in the switching electric field. The electrical and structural characteristics of varistors during and after breakdown are described qualitatively and quantitatively. Once breakdown is nucleated, the degradation typically follows a well-defined relationship between the number of post-initiation pulses and the degraded switching voltage. In some cases the degraded varistor has a remnant 20(micro)m diameter hollow track showing strong evidence of once-molten ZnO. A model is developed for both electrical and thermal effects during high energy pulsing. The breakdown is assumed to start at one electrode and advance towards the other electrode as a thin filament of conductive material that grows incrementally with each successive pulse. The model is partially validated by experiments in which the varistor rod is cut at several different lengths from the electrode. Invariably one section of the cut varistor has a switching field that is not degraded while the other section(s) are heavily degraded. Based on the experiments and models of behavior during breakdown, some speculations about the nature of the nucleating mechanism are offered in the last section

Qualitative Analysis of Dairy and Powder Milk Using Laser-Induced Breakdown Spectroscopy (LIBS).

Science.gov (United States)

Alfarraj, Bader A; Sanghapi, Herve K; Bhatt, Chet R; Yueh, Fang Y; Singh, Jagdish P

2018-01-01

Laser-induced breakdown spectroscopy (LIBS) technique was used to compare various types of commercial milk products. Laser-induced breakdown spectroscopy spectra were investigated for the determination of the elemental composition of soy and rice milk powder, dairy milk, and lactose-free dairy milk. The analysis was performed using radiative transitions. Atomic emissions from Ca, K, Na, and Mg lines observed in LIBS spectra of dairy milk were compared. In addition, proteins and fat level in milks can be determined using molecular emissions such as CN bands. Ca concentrations were calculated to be 2.165 ± 0.203 g/L in 1% of dairy milk fat samples and 2.809 ± 0.172 g/L in 2% of dairy milk fat samples using the standard addition method (SAM) with LIBS spectra. Univariate and multivariate statistical analysis methods showed that the contents of major mineral elements were higher in lactose-free dairy milk than those in dairy milk. The principal component analysis (PCA) method was used to discriminate four milk samples depending on their mineral elements concentration. In addition, proteins and fat level in dairy milks were determined using molecular emissions such as CN band. We applied partial least squares regression (PLSR) and simple linear regression (SLR) models to predict levels of milk fat in dairy milk samples. The PLSR model was successfully used to predict levels of milk fat in dairy milk sample with the relative accuracy (RA%) less than 6.62% using CN (0,0) band.

Electric field measurements in moving ionization fronts during plasma breakdown

NARCIS (Netherlands)

Wagenaars, E.; Bowden, M.D.; Kroesen, G.M.W.

2006-01-01

We have performed time-resolved, direct measurements of electric field strengths in moving ionization fronts during the breakdown phase of a pulsed plasma. Plasma breakdown, or plasma ignition, is a highly transient process marking the transition from a gas to a plasma. Some aspects of plasma

Surface of Alumina Films after Prolonged Breakdowns in Galvanostatic Anodization

Directory of Open Access Journals (Sweden)

Christian Girginov

2011-01-01

Full Text Available Breakdown phenomena are investigated at continuous isothermal (20∘C and galvanostatic (0.2–5 mA cm−2 anodizing of aluminum in ammonium salicylate in dimethylformamide (1 M AS/DMF electrolyte. From the kinetic (-curves, the breakdown voltage ( values are estimated, as well as the frequency and amplitude of oscillations of formation voltage ( at different current densities. The surface of the aluminum specimens was studied using atomic force microscopy (AFM. Data on topography and surface roughness parameters of the electrode after electric breakdowns are obtained as a function of anodization time. The electrode surface of anodic films, formed with different current densities until the same charge density has passed (2.5 C cm−2, was assessed. Results are discussed on the basis of perceptions of avalanche mechanism of the breakdown phenomena, due to the injection of electrons and their multiplication in the volume of the film.

Analysis of low-pressure dc breakdown in nitrogen between two spherical iron electrodes

International Nuclear Information System (INIS)

Pejovic, Momcilo M.; Nesic, Nikola T.; Pejovic, Milic M.

2006-01-01

The influence of afterglow period τ, voltage increase rate k, and electrode gap d on breakdown voltage U b for a nitrogen-filled tube with spherical electrodes of diameter D>>d and p=6.5 mbar has been investigated. The data for the breakdown voltage were obtained for the case when there is a presence of N( 4 S) atoms, which release secondary electrons via recombination on the cathode. By fitting the experimental data of breakdown voltage mean values as a function of the voltage increase rate, the static breakdown voltages for afterglow periods of 15 and 100 s were estimated. The electrical field as a function of the electrode gap using breakdown voltage mean values was also determined. It is shown that experimental results of the breakdown voltage mean value as a function of pd in the interval of d from 0.82 to 1.62 mm can be very well described with Paschen's law, valid for the case of parallel-plate electrodes

Protein turnover in lactating mink (Mustela vison) is not affected by dietary protein supply

DEFF Research Database (Denmark)

Tauson, Anne-Helene; Fink, Rikke; Chwalibog, André

2006-01-01

The mink is a strict carnivore and may therefore serve as a model for the cat. Current recommendations for protein supply for lactating mink are based on production experiments with preweaning kit growth as a measure of dietary adequacy (1,2). Recently, nitrogen balance and substrate oxidation have...... in humans (7), growing pigs (8), and growing rats (9). In adult cats, both protein synthesis and breakdown were lower when feeding a low- than when feeding a high-protein diet [20 vs. 70% of metabolizable energy (ME)5 from protein] (10). The objectives of this study were therefore to develop a ¹5N...

High-speed photography and holography of laser induced breakdown in liquids

International Nuclear Information System (INIS)

Lauterborn, W.

1979-01-01

Optical breakdown phenomena in liquids due to focused ruby laser light are investigated by high-speed photography and holography. Special attention is given the dynamics of the cavities produced in the liquid upon breakdown as they can be expected to become a powerful research tool in cavitation physics. To this end the production of three-dimensional breakdown configurations would be desirable as well as their investigation by high-speed holographic means. Both problems are presently under study. To achieve multiple breakdown at preselected points in the liquid a grating-lens assembly and digital holograms in photoresist are used. To film the motion of the cavities high-speed holocinematographic methods are developed. By now four to eight holograms can be taken at a rate of 10 to 20 kHz. (author)

Effects of polarization and absorption on laser induced optical breakdown threshold for skin rejuvenation

Science.gov (United States)

Varghese, Babu; Bonito, Valentina; Turco, Simona; Verhagen, Rieko

2016-03-01

Laser induced optical breakdown (LIOB) is a non-linear absorption process leading to plasma formation at locations where the threshold irradiance for breakdown is surpassed. In this paper we experimentally demonstrate the influence of polarization and absorption on laser induced breakdown threshold in transparent, absorbing and scattering phantoms made from water suspensions of polystyrene microspheres. We demonstrate that radially polarized light yields a lower irradiance threshold for creating optical breakdown compared to linearly polarized light. We also demonstrate that the thermal initiation pathway used for generating seed electrons results in a lower irradiance threshold compared to multiphoton initiation pathway used for optical breakdown.

Investigation of efficient termination structure for improved breakdown properties of semiconductor radiation detectors

International Nuclear Information System (INIS)

Krizaj, D.; Resnik, D.; Vrtacnik, D.; Amon, S.

1998-01-01

Efficiency of a new junction termination structure for improvement of breakdown properties of semiconductor radiation detectors is investigated. The structure consists of a diffused resistor winding around the active junction in a spiral fashion. The current flow through the spiral enables controlled potential distribution along the spiral turns and thus controlled depletion spreading from the main junction, efficiently preventing premature avalanche breakdown. Both multiple guard-ring structures and spiral junction termination structures have shown good breakdown properties typically three to five times higher than breakdown voltages of diodes without junction termination. The breakdown voltages of spiral junction termination structures are only weakly influenced by changes in substrate doping concentration caused by neutron irradiation. They can thus be considered for termination of future semiconductor radiation detectors

Dynamical symmetry breakdown in SU(5) and SO(10)

International Nuclear Information System (INIS)

Shellard, R.C.

1983-09-01

Some restrictions imposed upon Grand Unified Theories by dynamical symmetry breakdown are examined. It is observed in particular, that theories with SU(5) as symmetry group, with 3 or more fermion families undergo dynamical symmetry breakdown, and some of the fermions will acquire mass at the Grand Unified scale. On the other hand, the SO(10) group, with 3 families is free from this problem. (Author) [pt

RF Breakdown in Normal Conducting Single-cell Structures

CERN Document Server

Dolgashev, Valery A; Higo, Toshiyasu; Nantista, Christopher D; Tantawi, Sami G

2005-01-01

Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape and material. Experimental and theoretical study of the effects of these parameters on the breakdown limit in full scale structures is difficult and costly. We use 11.4 GHz single-cell traveling wave and standing wave accelerating structures for experiments and modeling of rf breakdown behavior. These test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype multicell structures for the X-band linear collider. Fields elsewhere in the test structures are significantly lower than that of the single cell. The setup uses matched mode converters that launch the circular TM01 mode into short test structures. The test structures are connected to the mode launchers with vacuum rf flanges. This setup allows economic testing of different cell geometries, cell materials an...

Runaway breakdown and electrical discharges in thunderstorms

Science.gov (United States)

Milikh, Gennady; Roussel-Dupré, Robert

2010-12-01

This review considers the precise role played by runaway breakdown (RB) in the initiation and development of lightning discharges. RB remains a fundamental research topic under intense investigation. The question of how lightning is initiated and subsequently evolves in the thunderstorm environment rests in part on a fundamental understanding of RB and cosmic rays and the potential coupling to thermal runaway (as a seed to RB) and conventional breakdown (as a source of thermal runaways). In this paper, we describe the basic mechanism of RB and the conditions required to initiate an observable avalanche. Feedback processes that fundamentally enhance RB are discussed, as are both conventional breakdown and thermal runaway. Observations that provide clear evidence for the presence of energetic particles in thunderstorms/lightning include γ-ray and X-ray flux intensifications over thunderstorms, γ-ray and X-ray bursts in conjunction with stepped leaders, terrestrial γ-ray flashes, and neutron production by lightning. Intense radio impulses termed narrow bipolar pulses (or NBPs) provide indirect evidence for RB particularly when measured in association with cosmic ray showers. Our present understanding of these phenomena and their enduring enigmatic character are touched upon briefly.

Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

International Nuclear Information System (INIS)

Babushok, V.I.; DeLucia, F.C.; Gottfried, J.L.; Munson, C.A.; Miziolek, A.W.

2006-01-01

A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of the double pulse laser induced breakdown spectroscopy technique: collinear, orthogonal pre-spark, orthogonal pre-heating and dual pulse crossed beam modes. In addition, combinations of laser pulses with different wavelengths, different energies and durations were studied, thus providing flexibility in the choice of wavelength, pulse width, energy and pulse sequence. The double pulse laser induced breakdown spectroscopy approach provides a significant enhancement in the intensity of laser induced breakdown spectroscopy emission lines up to two orders of magnitude greater than a conventional single pulse laser induced breakdown spectroscopy. The double pulse technique leads to a better coupling of the laser beam with the plasma plume and target material, thus providing a more temporally effective energy delivery to the plasma and target. The experimental results demonstrate that the maximum effect is obtained at some optimum separation delay time between pulses. The optimum value of the interpulse delay depends on several factors, such as the target material, the energy level of excited states responsible for the emission, and the type of enhancement process considered. Depending on the specified parameter, the enhancement effects were observed on different time scales ranging from the picosecond time level (e.g., ion yield, ablation mass) up to the hundred microsecond level (e.g., increased emission intensity for laser induced breakdown spectroscopy of submerged metal target in water). Several suggestions have been proposed to explain

A Coaxial Vortex Ring Model for Vortex Breakdown

OpenAIRE

Blackmore, Denis; Brons, Morten; Goullet, Arnaud

2008-01-01

A simple - yet plausible - model for B-type vortex breakdown flows is postulated; one that is based on the immersion of a pair of slender coaxial vortex rings in a swirling flow of an ideal fluid rotating around the axis of symmetry of the rings. It is shown that this model exhibits in the advection of passive fluid particles (kinematics) just about all of the characteristics that have been observed in what is now a substantial body of published research on the phenomenon of vortex breakdown....

Electrical Breakdown and Mechanical Ageing in Dielectric Elastomers

DEFF Research Database (Denmark)

Zakaria, Shamsul Bin

Dielectric elastomers (DE) are used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. For many applications, one of the major factors that limits the DE performance is premature electrical breakdown. There are many approaches that have been......, the lifetime of elastomer materials needs further investigation. Therefore, in the second strategy, several DE parameters such as Young’s moduli, breakdown strengths and dielectric permittivities of PDMS elastomers filled with hard filler particles were investigated after being subjected to pre...

Gas Breakdown of Radio Frequency Glow Discharges in Helium at near Atmospheric Pressure

International Nuclear Information System (INIS)

Liu Xinkun; Xu Jinzhou; Cui Tongfei; Guo Ying; Zhang Jing; Shi Jianjun

2013-01-01

A one-dimensional self-consistent fluid model was developed for radio frequency glow discharge in helium at near atmospheric pressure, and was employed to study the gas breakdown characteristics in terms of breakdown voltage. The effective secondary electron emission coefficient and the effective electric field for ions were demonstrated to be important for determining the breakdown voltage of radio frequency glow discharge at near atmospheric pressure. The constant of A was estimated to be 64±4 cm −1 Torr −1 , which was proportional to the first Townsend coefficient and could be employed to evaluate the gas breakdown voltage. The reduction in the breakdown voltage of radio frequency glow discharge with excitation frequency was studied and attributed to the electron trapping effect in the discharge gap

Breakdown Studies for the CLIC Accelerating

CERN Document Server

Calatroni, S; Kovermann, J; Taborelli, M; Timko, H; Wuensch, W; Durabekova, F; Nordlund, K; Pohjonen, A; Kuronen, A

2010-01-01

Optimizing the design and the manufacturing of the CLIC RF accelerating structures for achieving the target value of breakdown rate at the nominal accelerating gradient of 100 MV/m requires a detailed understanding of all the steps involved in the mechanism of breakdown. These include surface modification under RF fields, electron emission and neutral evaporation in the vacuum, arc ignition and consequent surface modification due to plasma bombardment. Together with RF tests, experiments are conducted in a simple DC test set-up instrumented with electrical diagnostics and optical spectroscopy. The results are also used for validating simulations which are performed using a wide range of numerical tools (MD coupled to electrostatic codes, PIC plasma simulations) able to include all the above phenomena. Some recent results are presented in this paper

Prevention of breakdown behind railgun projectiles

International Nuclear Information System (INIS)

Hawke, R.S.

1992-01-01

An electromagnetic railgun accelerator system, for accelerating projectiles by a plasma arc, introduces a breakdown inhibiting gas into the railgun chamber behind the accelerating projectile. The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF 6 . The gas is introduced between the railgun rails after the projectile has passed through inlets in the rails or the projectile; by coating the rails or the projectile with a material which releases the gas after the projectile passes over it; by fabricating the rails or the projectile or insulators out of a material which releases the gas into the portions of the chamber through which the projectile has travelled. The projectile may have a cavity at its rear to control the release of ablation products. 12 figs

A simple mechanism for controlling vortex breakdown in a closed flow

OpenAIRE

Cabeza, C.; Sarasua, Gustavo; Marti, Arturo C.; Bove, Italo

2005-01-01

This work is focused to study the development and control of the laminar vortex breakdown of a flow enclosed in a cylinder. We show that vortex breakdown can be controlled by the introduction of a small fixed rod in the axis of the cylinder. Our method to control the onset of vortex breakdown is simpler than those previously proposed, since it does not require any auxiliary device system. The effect of the fixed rods may be understood using a simple model based on the failure of the quasi-cyl...

Relations between rheological properties, saliva-induced structure breakdown and sensory texture attributes of custards

NARCIS (Netherlands)

Janssen, A.M.; Terpstra, M.E.J.; Wijk, R.A.de; Prinz, J.F.

2007-01-01

The relevance of initial rheological properties and mechanical and enzymatic structure breakdown in determining selected sensory texture attributes of custards was studied. The so-called structure breakdown cell was used to characterize saliva-induced breakdown, i.e., by monitoring digestion of

Improved model of activation energy absorption for different electrical breakdowns in semi-crystalline insulating polymers

Science.gov (United States)

Sima, Wenxia; Jiang, Xiongwei; Peng, Qingjun; Sun, Potao

2018-05-01

Electrical breakdown is an important physical phenomenon in electrical equipment and electronic devices. Many related models and theories of electrical breakdown have been proposed. However, a widely recognized understanding on the following phenomenon is still lacking: impulse breakdown strength which varies with waveform parameters, decrease in the breakdown strength of AC voltage with increasing frequency, and higher impulse breakdown strength than that of AC. In this work, an improved model of activation energy absorption for different electrical breakdowns in semi-crystalline insulating polymers is proposed based on the Harmonic oscillator model. Simulation and experimental results show that, the energy of trapped charges obtained from AC stress is higher than that of impulse voltage, and the absorbed activation energy increases with the increase in the electric field frequency. Meanwhile, the frequency-dependent relative dielectric constant ε r and dielectric loss tanδ also affect the absorption of activation energy. The absorbed activation energy and modified trap level synergistically determine the breakdown strength. The mechanism analysis of breakdown strength under various voltage waveforms is consistent with the experimental results. Therefore, the proposed model of activation energy absorption in the present work may provide a new possible method for analyzing and explaining the breakdown phenomenon in semi-crystalline insulating polymers.

The muscle protein synthetic response to food ingestion.

Science.gov (United States)

Gorissen, Stefan H M; Rémond, Didier; van Loon, Luc J C

2015-11-01

Preservation of skeletal muscle mass is of great importance for maintaining both metabolic health and functional capacity. Muscle mass maintenance is regulated by the balance between muscle protein breakdown and synthesis rates. Both muscle protein breakdown and synthesis rates have been shown to be highly responsive to physical activity and food intake. Food intake, and protein ingestion in particular, directly stimulates muscle protein synthesis rates. The postprandial muscle protein synthetic response to feeding is regulated on a number of levels, including dietary protein digestion and amino acid absorption, splanchnic amino acid retention, postprandial insulin release, skeletal muscle tissue perfusion, amino acid uptake by muscle, and intramyocellular signaling. The postprandial muscle protein synthetic response to feeding is blunted in many conditions characterized by skeletal muscle loss, such as aging and muscle disuse. Therefore, it is important to define food characteristics that modulate postprandial muscle protein synthesis. Previous work has shown that the muscle protein synthetic response to feeding can be modulated by changing the amount of protein ingested, the source of dietary protein, as well as the timing of protein consumption. Most of this work has studied the postprandial response to the ingestion of isolated protein sources. Only few studies have investigated the postprandial muscle protein synthetic response to the ingestion of protein dense foods, such as dairy and meat. The current review will focus on the capacity of proteins and protein dense food products to stimulate postprandial muscle protein synthesis and identifies food characteristics that may modulate the anabolic properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

How practice breakdowns disclose existing structures and contribute to practice innovation

NARCIS (Netherlands)

Loohuis, Raymond Petrus Antonius

2015-01-01

Practice breakdowns provide fertile ground for practice innovation because they demand a shift from structure to process. Practice breakdowns are fruitful subjects for research and practice because they disclose existing structures by prompting situated actors to become reflective on the otherwise

Humidity and polarity influence on MIM PZT capacitor degradation and breakdown

NARCIS (Netherlands)

Wang, Jiahui; Salm, Cora; Houwman, Evert; Schmitz, Jurriaan; Nguyen, Minh

2016-01-01

This paper presents a reliability study on unpackaged metal-PZT-metal capacitors. Both ramped voltage stress (RVS) and time dependent dielectric breakdown (TDDB) measurements show that environmental humidity dramatically worsens the PZT reliability. Visible breakdown spots on the surface of PZT

Reduction of space charge breakdown in e-beam irradiated nano/polymethyl methacrylate composites

International Nuclear Information System (INIS)

Zheng Feihu; Zhang Yewen; An Zhenlian; Dong Jianxing; Lei Qingquan

2013-01-01

Fast discharge of numerous space charges in dielectric materials can cause space charge breakdown. This letter reports the role of nanoparticles in affecting space charge breakdown of nano/polymethyl methacrylate composites. Space charge distributions in the composites, implanted by electron beam irradiation, were measured by pressure wave propagation method. The results show that the nanoparticles have significant effects on the isothermal charge decay and space charge breakdown in the nanocomposites. The resistance to space charge breakdown in the nanocomposites is attributed to the combined action of the introduction of deep trapping states and the scattering effect by the added nanoparticles.

Experimental dependence of ECR plasma breakdown on wave polarization in the TJ-II stellarator

International Nuclear Information System (INIS)

Cappa, A.; Castejon, F.; Tabares, F.; Fernandez, A.; Tafalla, D.; Cal, E. de la; Estrada, T.; Nagasaki, K.

2005-01-01

Recently, second harmonic ECRH plasma breakdown and its dependence on the initial conditions such as neutral gas pressure, injected power or beam polarization has been the subject of theoretical as well as experimental work. Although those studies have been carried out in the context of stellarators, they are particularly relevant in the case of large tokamaks, such as ITER, where conventional inductive breakdown is expected to be strongly improved if ECRH is used. A matter of interest is the dependence of breakdown time on wave polarization. In the existing theoretical models, wave polarization is not taken into account because it is assumed that the injected ECRH power is initially scrambled by the vessel walls and that the energy source for breakdown is only due to the non-linear wave-particle interaction between deeply trapped electrons and the averaged electric field. However, while this seems reasonable for the very beginning of the discharge, it may not be so as we progress towards breakdown. Actually, as experiments in Heliotron J have demonstrated, wave polarization must be taken into account in the description of the energy source. Breakdown experiments in TJ-II were performed in order to get a deep insight into this matter and part of the results of breakdown dependence on wave polarization were already discussed. In particular, it was demonstrated that the hypothesis about the energy source used in the models is failing long before full ionization is completed. But more information in relation with our understanding of the second harmonic ECRH breakdown, such as the toroidal and radial breakdown propagation, which is seen to be non-diffusive, can be extracted. Thus, the experiment results provide valuable data that can be used not only to improve the energy source but also to include spatial dimensions in the breakdown models. (author)

Role of growth hormone, insulin-like growth factor-I, and insulin-like growth factor binding proteins in the catabolic response to injury and infection.

Science.gov (United States)

Lang, Charles H; Frost, Robert A

2002-05-01

The erosion of lean body mass resulting from protracted critical illness remains a significant risk factor for increased morbidity and mortality in this patient population. Previous studies have documented the well known impairment in nitrogen balance results from both an increase in muscle protein degradation as well as a decreased rate of both myofibrillar and sacroplasmic protein synthesis. This protein imbalance may be caused by an increased presence or activity of various catabolic agents, such as tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6 or glucocorticoids, or may be mediated via a decreased concentration or responsiveness to various anabolic hormones, such as growth hormone or insulin-like growth factor-I. This review focuses on recent developments pertaining to the importance of alterations in the growth hormone-insulin-like growth factor-I axis as a mechanism for the observed defects in muscle protein balance.

Experimental vortex breakdown topology in a cylinder with a free surface

DEFF Research Database (Denmark)

Lo Jacono, D.; Nazarinia, M.; Brøns, Morten

2009-01-01

The free SLII-face, flow in it circular cylinder driven by a rotating bottom disk IS Studied experimentally using particle image velocimetry. Results are compared With computational,11 results assuming I stress-free surface A dye visualization Study by Spohn et al ["Observations of vortex breakdown...... in in open cylindrical container with I rotating bottom," Exp. Fluids 14. 70 (1993)]v as well as several numerical computations. has found a range of different vortex breakdown Structures in this flow. We confirm the existence of a transition where the top of the breakdown bubble crosses from the axis...... to the surface, which has previously only been found numerically. We employ a technique by Brons et al ["Topology of vortex breakdown bubbles in I cylinder with rotating bottom and free surface J. Fluid Mech 428. 133 (2001)] to find the corresponding bifurcation curve in the parameter plane, which has hitherto...

Electric properties and carrier multiplication in breakdown sites in multi-crystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Schneemann, Matthias; Carius, Reinhard; Rau, Uwe [IEK5-Photovoltaics, Forschungszentrum Jülich, Jülich 52425 (Germany); Kirchartz, Thomas, E-mail: t.kirchartz@fz-juelich.de [IEK5-Photovoltaics, Forschungszentrum Jülich, Jülich 52425 (Germany); Faculty of Engineering and CENIDE, University of Duisburg-Essen, Carl-Benz-Str. 199, Duisburg 47057 (Germany)

2015-05-28

This paper studies the effective electrical size and carrier multiplication of breakdown sites in multi-crystalline silicon solar cells. The local series resistance limits the current of each breakdown site and is thereby linearizing the current-voltage characteristic. This fact allows the estimation of the effective electrical diameters to be as low as 100 nm. Using a laser beam induced current (LBIC) measurement with a high spatial resolution, we find carrier multiplication factors on the order of 30 (Zener-type breakdown) and 100 (avalanche breakdown) as new lower limits. Hence, we prove that also the so-called Zener-type breakdown is followed by avalanche multiplication. We explain that previous measurements of the carrier multiplication using thermography yield results higher than unity, only if the spatial defect density is high enough, and the illumination intensity is lower than what was used for the LBIC method. The individual series resistances of the breakdown sites limit the current through these breakdown sites. Therefore, the measured multiplication factors depend on the applied voltage as well as on the injected photocurrent. Both dependencies are successfully simulated using a series-resistance-limited diode model.

RF Breakdown Studies Using a 1.3 GHZ Test Cell

International Nuclear Information System (INIS)

Sah, R.; Johnson, R.P.; Neubauer, M.; Conde, M.; Gai, W.; Moretti, A.; Popovic, M.; Yonehara, K.; Byrd, J.; Li, D.; BastaniNejad, M.

2009-01-01

Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) and pressure barrier capable of operating both at high pressure and in vacuum has been designed and built, and preliminary testing has been completed. A series of detailed experiments is planned at the Argonne Wakefield Accelerator. At the same time, computer simulations of the RF Breakdown process will be carried out to help develop a consistent physics model of RF Breakdown. In order to study the effect of the radiofrequency on RF Breakdown, a second test cell will be designed, fabricated, and tested at a lower frequency, most likely 402.5 MHz.

The electrical breakdown strength of pre-stretched elastomers, with and without sample volume conservation

DEFF Research Database (Denmark)

Zakaria, Shamsul Bin; Morshuis, Peter H. F.; Yahia, Benslimane Mohamed

2015-01-01

In practice, the electrical breakdown strength of dielectric electroactive polymers (DEAPs)determines the upper limit for transduction. During DEAP actuation, the thickness of the elastomer decreases, and thus the electrical field increases and the breakdown process is determined by a coupled...... electro-mechanical failure mechanism. A thorough understanding of the mechanisms behind the electro-mechanical breakdown process is required for developing reliable transducers. In this study, two experimental configurations were used to determine the stretch dependence of the electrical breakdown...

Identification of small peptides arising from hydrolysis of meat proteins in dry fermented sausages.

Science.gov (United States)

López, Constanza M; Bru, Elena; Vignolo, Graciela M; Fadda, Silvina G

2015-06-01

In this study, proteolysis and low molecular weight (LMW) peptides (<3kDa) from commercial Argentinean fermented sausages were characterized by applying a peptidomic approach. Protein profiles and peptides obtained by Tricine-SDS-PAGE and RP-HPLC-MS, respectively, allowed distinguishing two different types of fermented sausages, although no specific biomarkers relating to commercial brands or quality were recognized. From electrophoresis, α-actin, myoglobin, creatine kinase M-type and L-lactate dehydrogenase were degraded at different intensities. In addition, a partial characterization of fermented sausage peptidome through the identification of 36 peptides, in the range of 1000-2100 Da, arising from sarcoplasmic (28) and myofibrillar (8) proteins was achieved. These peptides had been originated from α-actin, myoglobin, and creatine kinase M-type, but also from the hydrolysis of other proteins not previously reported. Although muscle enzymes exerted a major role on peptidogenesis, microbial contribution cannot be excluded as it was postulated herein. This work represents a first peptidomic approach for fermented sausages, thereby providing a baseline to define key peptides acting as potential biomarkers. Copyright © 2015 Elsevier Ltd. All rights reserved.

On the breakdown modes and parameter space of Ohmic Tokamak startup

Science.gov (United States)

Peng, Yanli; Jiang, Wei; Zhang, Ya; Hu, Xiwei; Zhuang, Ge; Innocenti, Maria; Lapenta, Giovanni

2017-10-01

Tokamak plasma has to be hot. The process of turning the initial dilute neutral hydrogen gas at room temperature into fully ionized plasma is called tokamak startup. Even with over 40 years of research, the parameter ranges for the successful startup still aren't determined by numerical simulations but by trial and errors. However, in recent years it has drawn much attention due to one of the challenges faced by ITER: the maximum electric field for startup can't exceed 0.3 V/m, which makes the parameter range for successful startup narrower. Besides, this physical mechanism is far from being understood either theoretically or numerically. In this work, we have simulated the plasma breakdown phase driven by pure Ohmic heating using a particle-in-cell/Monte Carlo code, with the aim of giving a predictive parameter range for most tokamaks, even for ITER. We have found three situations during the discharge, as a function of the initial parameters: no breakdown, breakdown and runaway. Moreover, breakdown delay and volt-second consumption under different initial conditions are evaluated. In addition, we have simulated breakdown on ITER and confirmed that when the electric field is 0.3 V/m, the optimal pre-filling pressure is 0.001 Pa, which is in good agreement with ITER's design.

Breakdown of coupling dielectrics for Si microstrip detectors

International Nuclear Information System (INIS)

Candelori, A.; Paccagnella, A.; Padova Univ.; Saglimbeni, G.

1999-01-01

Double-layer coupling dielectrics for AC-coupled Si microstrip detectors have been electrically characterized in order to determine their performance in a radiation-harsh environment, with a focus on the dielectric breakdown. Two different dielectric technologies have been investigated: SiO 2 /TEOS and SiO 2 /Si 3 N 4 . Dielectrics have been tested by using a negative gate voltage ramp of 0.2 MV/(cm·s). The metal/insulator/Si I-V characteristics show different behaviours depending on the technology. The extrapolated values of the breakdown field for unirradiated devices are significantly higher for SiO 2 /Si 3 N 4 dielectrics, but the data dispersion is lower for SiO 2 /TEOS devices. No significant variation of the breakdown field has been measured after a 10 Mrad (Si) γ irradiation for SiO 2 /Si 3 N 4 dielectrics. Finally, the SiO 2 /Si 3 N 4 DC conduction is enhanced if a positive gate voltage ramp is applied with respect to the negative one, due to the asymmetric conduction of the double-layer dielectric

Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

Science.gov (United States)

Pearson, Richard G.; Hui, Cang; Gessner, Mark O.; Pérez, Javier; Alexandrou, Markos A.; Graça, Manuel A. S.; Cardinale, Bradley J.; Albariño, Ricardo J.; Arunachalam, Muthukumarasamy; Barmuta, Leon A.; Boulton, Andrew J.; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G.; Dudgeon, David; Encalada, Andrea C.; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S.; Gonçalves, José F.; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S.; Pringle, Catherine M.; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M.

2016-01-01

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons. PMID:27122551

Spontaneous symmetry breakdown in gauge theories

International Nuclear Information System (INIS)

Scadron, M.D.

1982-01-01

The dynamical theory of spontaneous breakdown correctly predicts the bound states and relates the order parameters of electron-photon superconductivity and quark-gluon chiral symmetry. A similar statement cannot be made for the standard electro-weak gauge symmetry. (author)

Relativistic runaway breakdown in low-frequency radio

Science.gov (United States)

Füllekrug, Martin; Roussel-Dupré, Robert; Symbalisty, Eugene M. D.; Chanrion, Olivier; Odzimek, Anna; van der Velde, Oscar; Neubert, Torsten

2010-01-01

The electromagnetic radiation emitted by an electron avalanche beam resulting from relativistic runaway breakdown within the Earth's atmosphere is investigated. It is found from theoretical modeling with a computer simulation that the electron beam emits electromagnetic radiation which is characterized by consecutive broadband pulses in the low-frequency radio range from ˜10 to 300 kHz at a distance of ˜800 km. Experimental evidence for the existence of consecutive broadband pulses is provided by low-frequency radio observations of sprite-producing lightning discharges at a distance of ˜550 km. The measured broadband pulses occur ˜4-9 ms after the sprite-producing lightning discharge, they exhibit electromagnetic radiation which mainly spans the frequency range from ˜50 to 350 kHz, and they exhibit complex waveforms without the typical ionospheric reflection of the first hop sky wave. Two consecutive pulses occur ˜4.5 ms and ˜3 ms after the causative lightning discharge and coincide with the sprite luminosity. It is concluded that relativistic runaway breakdown within the Earth's atmosphere can emit broadband electromagnetic pulses and possibly generates sprites. The source location of the broadband pulses can be determined with an interferometric network of wideband low-frequency radio receivers to lend further experimental support to the relativistic runaway breakdown theory.

Electronic individual breakdown of pension rights and/or transfer value

CERN Document Server

Pension Fund

2011-01-01

Commencing this year, members of the personnel will be notified by e-mail of their annual breakdown of pension rights and/or transfer value. Each person receiving the e-mail notification will be invited to consult this breakdown by clicking on a link protected by AISlogin and a password. Benefits Service of the Pension Fund pension-benefits@cern.ch  

Breakdown Localization Studies on the SwissFEL C-band Test Structures

CERN Document Server

Klavins, J; Le Pimpec, F; Locans, U; Shipman, N; Stingelin, L; Wohlmuther, M; Zennaro, R

2013-01-01

The SwissFEL main LINAC will consist of 104 Cband structures with a nominal accelerating gradient of 28MV/m. First power tests were performed on short constant impedance test-structures composed of eleven double-rounded cups. In order to localize breakdowns, two or three acoustic emission sensors were installed on the test-structures. In order to localize breakdowns we have analysed, in addition to acoustic measurements, the delay and phase of the RF power signals. Parasitic, acoustic noise emitted from the loads of the structure complicated the data interpretation and necessitated appropriate processing of the acoustic signals. The Goals of the experiments were to identify design and manufacturing errors of the structures. The results indicate that breakdowns occur mostly at the input power coupler, as also confirmed by vacuumevents at the same location. The experiments show that the LINAC test-structures fulfil the requirements in breakdown probability. Moreover developing a detection system based on acoust...

Characteristics and Breakdown Behaviors of Polysilicon Resistors for High Voltage Applications

Directory of Open Access Journals (Sweden)

Xiao-Yu Tang

2015-01-01

Full Text Available With the rapid development of the power integrated circuit technology, polysilicon resistors have been widely used not only in traditional CMOS circuits, but also in the high voltage applications. However, there have been few detailed reports about the polysilicon resistors’ characteristics, like voltage and temperature coefficients and breakdown behaviors which are critical parameters of high voltage applications. In this study, we experimentally find that the resistance of the polysilicon resistor with a relatively low doping concentration shows negative voltage and temperature coefficients, while that of the polysilicon resistor with a high doping concentration has positive voltage and temperature coefficients. Moreover, from the experimental results of breakdown voltages of the polysilicon resistors, it could be deduced that the breakdown of polysilicon resistors is thermally rather than electrically induced. We also proposed to add an N-type well underneath the oxide to increase the breakdown voltage in the vertical direction when the substrate is P-type doped.

Influence of magnetic field on the electrical breakdown characteristics in cylindrical diode

International Nuclear Information System (INIS)

Li Shouzhe; Uhm, Han S.

2004-01-01

The influence of magnetic field on the electrical breakdown properties is investigated by applying a magnetic field along the longitudinal direction in a cylindrical diode for two electrical polarities. Breakdown characteristics in a crossed magnetic field are analyzed with the equivalentreduced-electric-field concept and Townsend criterion. The discharge experiment at reduced pressure is carried out in the moderate magnetic field. Experimental investigation is concentrated on the magnetic dependent behavior of the electrical breakdown in the lower pressure side of Paschen's minimum. It is found that the electrical breakdown characteristics with respect to the magnetic field depend on electrical polarity of the cylindrical diode, which is interpreted by taking the gyromotion of the individual electrons in the diode into accounts under the moderate magnetic field in the lower pressure side of Paschen's minimum

Effects of macro-nutrient, micro-nutrient composition and cooking conditions on in vitro digestibility of meat and aquatic dietary proteins.

Science.gov (United States)

Luo, Jiaqiang; Taylor, Cheryl; Nebl, Thomas; Ng, Ken; Bennett, Louise E

2018-07-15

Animal and aquatic meats represent important sources of dietary protein and micro-nutrients. Although red and processed meats carry some risks for human health, sensory and nutritional advantages drive meat consumption. Therefore, it is important to understand how meat processing and cooking influence healthiness. The research aim was to investigate relationships of meat composition (proximates, amino acids and minerals) and cooking conditions (raw, 90 s microwave, 200 °C oven for 10 or 30 min) on protein digestibility, for a selection of four animal (beef, chicken, pork, kangaroo) and four aquatic meats (salmon, trout, prawn, oyster). Lean meats were minced before cooking followed by in vitro gastro-intestinal digestion and analysed for progress of hydrolysis, and size ranges of peptides using MALDI-TOF-MS. Correlation matrix analysis between compositional and functional parameters indicated that digestibility was significantly linked with protein and metal concentrations, likely reflecting moisture-dependent solubility and inter-mixing of sarcoplasmic metallo-proteins and insoluble myofibrillar proteins. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Particle size analysis of lamb meat: Effect of homogenization speed, comparison with myofibrillar fragmentation index and its relationship with shear force.

Science.gov (United States)

Karumendu, L U; Ven, R van de; Kerr, M J; Lanza, M; Hopkins, D L

2009-08-01

The impact of homogenization speed on Particle Size (PS) results was examined using samples from the M.longissimus thoracis et lumborum (LL) of 40 lambs. One gram duplicate samples from meat aged for 1 and 5days were homogenized at five different speeds; 11,000, 13,000, 16,000, 19,000 and 22,000rpm. In addition to this LL samples from 30 different lamb carcases also aged for 1 and 5days were used to study the comparison between PS and myofibrillar fragmentation index (MFI) values. In this case, 1g duplicate samples (n=30) were homogenized at 16,000rpm and the other half (0.5g samples) at 11,000rpm (n=30). The homogenates were then subjected to respective combinations of treatments which included either PS analysis or the determination of MFI, both with or without three cycles of centrifugation. All 140 samples of LL included 65g blocks for subsequent shear force (SF) testing. Homogenization at 16,000rpm provided the greatest ability to detect ageing differences for particle size between samples aged for 1 and 5days. Particle size at the 25% quantile provided the best result for detecting differences due to ageing. It was observed that as ageing increased the mean PS decreased and was significantly (P<0.001) less for 5days aged samples compared to 1day aged samples, while MFI values significantly increased (P<0.001) as ageing period increased. When comparing the PS and MFI methods it became apparent that, as opposed to the MFI method, there was a greater coefficient of variation for the PS method which warranted a quality assurance system. Given this requirement and examination of the mean, standard deviation and the 25% quantile for PS data it was concluded that three cycles of centrifugation were not necessary and this also applied to the MFI method. There were significant correlations (P<0.001) within the same lamb loin sample aged for a given period between mean MFI and mean PS (-0.53), mean MFI and mean SF (-0.38) and mean PS and mean SF (0.23). It was

Double helix vortex breakdown in a turbulent swirling annular jet flow

NARCIS (Netherlands)

Vanierschot, M.; Perçin, M.; van Oudheusden, B.W.

2018-01-01

In this paper, we report on the structure and dynamics of double helix vortex breakdown in a turbulent annular swirling jet. Double helix breakdown has been reported previously for the laminar flow regime, but this structure has rarely been observed in turbulent flow. The flow field is

Effects of continuum breakdown on hypersonic aerothermodynamics for reacting flow

Science.gov (United States)

Holman, Timothy D.; Boyd, Iain D.

2011-02-01

This study investigates the effects of continuum breakdown on the surface aerothermodynamic properties (pressure, stress, and heat transfer rate) of a sphere in a Mach 25 flow of reacting air in regimes varying from continuum to a rarefied gas. Results are generated using both continuum [computational fluid dynamics (CFD)] and particle [direct simulation Monte Carlo (DSMC)] approaches. The DSMC method utilizes a chemistry model that calculates the backward rates from an equilibrium constant. A preferential dissociation model is modified in the CFD method to better compare with the vibrationally favored dissociation model that is utilized in the DSMC method. Tests of these models are performed to confirm their validity and to compare the chemistry models in both numerical methods. This study examines the effect of reacting air flow on continuum breakdown and the surface properties of the sphere. As the global Knudsen number increases, the amount of continuum breakdown in the flow and on the surface increases. This increase in continuum breakdown significantly affects the surface properties, causing an increase in the differences between CFD and DSMC. Explanations are provided for the trends observed.

Thermoplastic processing of proteins for film formation--a review.

Science.gov (United States)

Hernandez-Izquierdo, V M; Krochta, J M

2008-03-01

Increasing interest in high-quality food products with increased shelf life and reduced environmental impact has encouraged the study and development of edible and/or biodegradable polymer films and coatings. Edible films provide the opportunity to effectively control mass transfer among different components in a food or between the food and its surrounding environment. The diversity of proteins that results from an almost limitless number of side-chain amino-acid sequential arrangements allows for a wide range of interactions and chemical reactions to take place as proteins denature and cross-link during heat processing. Proteins such as wheat gluten, corn zein, soy protein, myofibrillar proteins, and whey proteins have been successfully formed into films using thermoplastic processes such as compression molding and extrusion. Thermoplastic processing can result in a highly efficient manufacturing method with commercial potential for large-scale production of edible films due to the low moisture levels, high temperatures, and short times used. Addition of water, glycerol, sorbitol, sucrose, and other plasticizers allows the proteins to undergo the glass transition and facilitates deformation and processability without thermal degradation. Target film variables, important in predicting biopackage performance under various conditions, include mechanical, thermal, barrier, and microstructural properties. Comparisons of film properties should be made with care since results depend on parameters such as film-forming materials, film formulation, fabrication method, operating conditions, testing equipment, and testing conditions. Film applications include their use as wraps, pouches, bags, casings, and sachets to protect foods, reduce waste, and improve package recyclability.

Effects of Preslaughter Stress Levels on the Post-mortem Sarcoplasmic Proteomic Profile of Gilthead Seabream Muscle

DEFF Research Database (Denmark)

Silva, Tomé Santos; Cordeiro, Odete D; Matos, Elisabete D.

2012-01-01

identification was performed by MALDI-TOF-TOF MS. Analysis of the results indicates changes on several cellular pathways, with some of these changes being attributable to oxidative and proteolytic activity on sarcoplasmic proteins, together with leaking of myofibrillar proteins. These processes appear to have...

Experimental study of vortex breakdown in a cylindrical, swirling flow

Science.gov (United States)

Stevens, J. L.; Celik, Z. Z.; Cantwell, B. J.; Lopez, J. M.

1996-01-01

The stability of a steady, vortical flow in a cylindrical container with one rotating endwall has been experimentally examined to gain insight into the process of vortex breakdowwn. The dynamics of the flow are governed by the Reynolds number (Re) and the aspect ratio of the cylinder. Re is given by Omega R(sup 2)/nu, where Omega is the speed of rotation of the endwall, R is the cylinder radius, and nu is the kinematic viscosity of the fluid filling the cylinder. The aspect ratio is H/R, where H is the height of the cylinder. Numerical simulation studies disagree whether or not the steady breakdown is stable beyond a critical Reynolds number, Re(sub c). Previous experimental researches have considered the steady and unsteady flows near Re(sub c), but have not explored the stability of the steady breakdown structures beyond this value. In this investigation, laser induced fluorescence was utilized to observe both steady and unsteady vortex breakdown at a fixed H/R of 2.5 with Re varying around Re(sub c). When the Re of a steady flow was slowly increased beyond Re(sub c), the breakdown structure remained steady even though unsteadiness was possible. In addition, a number of hysteresis events involving the oscillation periods of the unsteady flow were noted. The results show that both steady and unsteady vortex breakdown occur for a limited range of Re above Re(sub c). Also, with increasing Re, complex flow transformations take place that alter the period at which the unsteady flow oscillates.

Space Charge Modulated Electrical Breakdown of Oil Impregnated Paper Insulation Subjected to AC-DC Combined Voltages

Directory of Open Access Journals (Sweden)

Yuanwei Zhu

2018-06-01

Full Text Available Based on the existing acknowledgment that space charge modulates AC and DC breakdown of insulating materials, this investigation promotes the related investigation into the situations of more complex electrical stress, i.e., AC-DC combined voltages. Experimentally, the AC-DC breakdown characteristics of oil impregnated paper insulation were systematically investigated. The effects of pre-applied voltage waveform, AC component ratio, and sample thickness on AC-DC breakdown characteristics were analyzed. After that, based on an improved bipolar charge transport model, the space charge profiles and the space charge induced electric field distortion during AC-DC breakdown were numerically simulated to explain the differences in breakdown characteristics between the pre-applied AC and pre-applied DC methods under AC-DC combined voltages. It is concluded that large amounts of homo-charges are accumulated during AC-DC breakdown, which results in significantly distorted inner electric field, leading to variations of breakdown characteristics of oil impregnated paper insulation. Therefore, space charges under AC-DC combined voltages must be considered in the design of converter transformers. In addition, this investigation could provide supporting breakdown data for insulation design of converter transformers and could promote better understanding on the breakdown mechanism of insulating materials subjected to AC-DC combined voltages.

New phenomenology of gas breakdown in DC and RF fields

Science.gov (United States)

Petrović, Zoran Lj; Sivoš, Jelena; Savić, Marija; Škoro, Nikola; Radmilović Radenović, Marija; Malović, Gordana; Gocić, Saša; Marić, Dragana

2014-05-01

This paper follows a review lecture on the new developments in the field of gas breakdown and low current discharges, usually covered by a form of Townsend's theory and phenomenology. It gives an overview of a new approach to identifying which feedback agents provide breakdown, how to model gas discharge conditions and reconcile the results with binary experiments and how to employ that knowledge in modelling gas discharges. The next step is an illustration on how to record volt-ampere characteristics and use them on one hand to obtain the breakdown voltage and, on the other, to identify the regime of operation and model the secondary electron yields. The second aspect of this section concerns understanding the different regimes, their anatomy, how those are generated and how free running oscillations occur. While temporal development is the most useful and interesting part of the new developments, the difficulty of presenting the data in a written form precludes an easy publication and discussion. Thus, we shall only mention some of the results that stem from these measurements. Most micro discharges operate in DC albeit with complex geometries. Thus, parallel plate micro discharge measurements were needed to establish that Townsend's theory, with all its recent extensions, is still valid until some very small gaps. We have shown, for example, how a long-path breakdown puts in jeopardy many experimental observations and why a flat left-hand side of the Paschen curve often does not represent good physics. We will also summarize a kinetic representation of the RF breakdown revealing a somewhat more complex picture than the standard model. Finally, we will address briefly the breakdown in radially inhomogeneous conditions and how that affects the measured properties of the discharge. This review has the goal of summarizing (rather than developing details of) the current status of the low-current DC discharges formation and operation as a discipline which, in spite of

Relativistic runaway breakdown in low-frequency radio

DEFF Research Database (Denmark)

Fullekrug, M.; Roussel-Dupre, R.; Symbalisty, E.M.D.

2011-01-01

at a distance of similar to 550 km. The measured broadband pulses occur similar to 4-9 ms after the sprite-producing lightning discharge, they exhibit electromagnetic radiation which mainly spans the frequency range from similar to 50 to 350 kHz, and they exhibit complex waveforms without the typical...... electromagnetic pulses and possibly generates sprites. The source location of the broadband pulses can be determined with an interferometric network of wideband low-frequency radio receivers to lend further experimental support to the relativistic runaway breakdown theory.......The electromagnetic radiation emitted by an electron avalanche beam resulting from relativistic runaway breakdown within the Earth's atmosphere is investigated. It is found from theoretical modeling with a computer simulation that the electron beam emits electromagnetic radiation which...

Numerical simulation of incidence and sweep effects on delta wing vortex breakdown

Science.gov (United States)

Ekaterinaris, J. A.; Schiff, Lewis B.

1994-01-01

The structure of the vortical flowfield over delta wings at high angles of attack was investigated. Three-dimensional Navier-Stokes numerical simulations were carried out to predict the complex leeward-side flowfield characteristics, including leading-edge separation, secondary separation, and vortex breakdown. Flows over a 75- and a 63-deg sweep delta wing with sharp leading edges were investigated and compared with available experimental data. The effect of variation of circumferential grid resolution grid resolution in the vicinity of the wing leading edge on the accuracy of the solutions was addressed. Furthermore, the effect of turbulence modeling on the solutions was investigated. The effects of variation of angle of attack on the computed vortical flow structure for the 75-deg sweep delta wing were examined. At moderate angles of attack no vortex breakdown was observed. When a critical angle of attack was reached, bubble-type vortex breakdown was found. With further increase in angle of attack, a change from bubble-type breakdown to spiral-type vortex breakdown was predicted by the numerical solution. The effects of variation of sweep angle and freestream Mach number were addressed with the solutions on a 63-deg sweep delta wing.

Soy-dairy protein blend and whey protein ingestion after resistance exercise increases amino acid transport and transporter expression in human skeletal muscle

Science.gov (United States)

Reidy, P. T.; Walker, D. K.; Dickinson, J. M.; Gundermann, D. M.; Drummond, M. J.; Timmerman, K. L.; Cope, M. B.; Mukherjea, R.; Jennings, K.; Volpi, E.

2014-01-01

Increasing amino acid availability (via infusion or ingestion) at rest or postexercise enhances amino acid transport into human skeletal muscle. It is unknown whether alterations in amino acid availability, from ingesting different dietary proteins, can enhance amino acid transport rates and amino acid transporter (AAT) mRNA expression. We hypothesized that the prolonged hyperaminoacidemia from ingesting a blend of proteins with different digestion rates postexercise would enhance amino acid transport into muscle and AAT expression compared with the ingestion of a rapidly digested protein. In a double-blind, randomized clinical trial, we studied 16 young adults at rest and after acute resistance exercise coupled with postexercise (1 h) ingestion of either a (soy-dairy) protein blend or whey protein. Phenylalanine net balance and transport rate into skeletal muscle were measured using stable isotopic methods in combination with femoral arteriovenous blood sampling and muscle biopsies obtained at rest and 3 and 5 h postexercise. Phenylalanine transport into muscle and mRNA expression of select AATs [system L amino acid transporter 1/solute-linked carrier (SLC) 7A5, CD98/SLC3A2, system A amino acid transporter 2/SLC38A2, proton-assisted amino acid transporter 1/SLC36A1, cationic amino acid transporter 1/SLC7A1] increased to a similar extent in both groups (P protein blend resulted in a prolonged and positive net phenylalanine balance during postexercise recovery compared with whey protein (P protein synthesis increased similarly between groups. We conclude that, while both protein sources enhanced postexercise AAT expression, transport into muscle, and myofibrillar protein synthesis, postexercise ingestion of a protein blend results in a slightly prolonged net amino acid balance across the leg compared with whey protein. PMID:24699854

The effects of glucosinolates and their breakdown products on necrotrophic fungi.

Directory of Open Access Journals (Sweden)

Kobi Buxdorf

Full Text Available Glucosinolates are a diverse class of S- and N-containing secondary metabolites that play a variety of roles in plant defense. In this study, we used Arabidopsis thaliana mutants that contain different amounts of glucosinolates and glucosinolate-breakdown products to study the effects of these phytochemicals on phytopathogenic fungi. We compared the fungus Botrytis cinerea, which infects a variety of hosts, with the Brassicaceae-specific fungus Alternaria brassicicola. B. cinerea isolates showed variable composition-dependent sensitivity to glucosinolates and their hydrolysis products, while A. brassicicola was more strongly affected by aliphatic glucosinolates and isothiocyanates as decomposition products. We also found that B. cinerea stimulates the accumulation of glucosinolates to a greater extent than A. brassicicola. In our work with A. brassicicola, we found that the type of glucosinolate-breakdown product is more important than the type of glucosinolate from which that product was derived, as demonstrated by the sensitivity of the Ler background and the sensitivity gained in Col-0 plants expressing epithiospecifier protein both of which accumulate simple nitrile and epithionitriles, but not isothiocyanates. Furthermore, in vivo, hydrolysis products of indole glucosinolates were found to be involved in defense against B. cinerea, but not in the host response to A. brassicicola. We suggest that the Brassicaceae-specialist A. brassicicola has adapted to the presence of indolic glucosinolates and can cope with their hydrolysis products. In contrast, some isolates of the generalist B. cinerea are more sensitive to these phytochemicals.

Investigation of dielectric breakdown in silica-epoxy nanocomposites using designed interfaces.

Science.gov (United States)

Bell, Michael; Krentz, Timothy; Keith Nelson, J; Schadler, Linda; Wu, Ke; Breneman, Curt; Zhao, Su; Hillborg, Henrik; Benicewicz, Brian

2017-06-01

Adding nano-sized fillers to epoxy has proven to be an effective method for improving dielectric breakdown strength (DBS). Evidence suggests that dispersion state, as well as chemistry at the filler-matrix interface can play a crucial role in property enhancement. Herein we investigate the contribution of both filler dispersion and surface chemistry on the AC dielectric breakdown strength of silica-epoxy nanocomposites. Ligand engineering was used to synthesize bimodal ligands onto 15nm silica nanoparticles consisting of long epoxy compatible, poly(glycidyl methacrylate) (PGMA) chains, and short, π-conjugated, electroactive surface ligands. Surface initiated RAFT polymerization was used to synthesize multiple graft densities of PGMA chains, ultimately controlling the dispersion of the filler. Thiophene, anthracene, and terthiophene were employed as π-conjugated surface ligands that act as electron traps to mitigate avalanche breakdown. Investigation of the synthesized multifunctional nanoparticles was effective in defining the maximum particle spacing or free space length (L f ) that still leads to property enhancement, as well as giving insight into the effects of varying the electronic nature of the molecules at the interface on breakdown strength. Optimization of the investigated variables was shown to increase the AC dielectric breakdown strength of epoxy composites as much as 34% with only 2wt% silica loading. Copyright © 2017 Elsevier Inc. All rights reserved.

The wavelength dependence of gold nanorod-mediated optical breakdown during infrared ultrashort pulses

Energy Technology Data Exchange (ETDEWEB)

Davletshin, Yevgeniy R.; Kumaradas, J. Carl [Department of Physics, Ryerson University, Toronto, ON (Canada)

2017-04-15

This paper investigates the wavelength dependence of the threshold of gold nanorod-mediated optical breakdown during picosecond and femtosecond near infrared optical pulses. It was found that the wavelength dependence in the picosecond regime is governed solely by the changes of a nanorod's optical properties. On the other hand, the optical breakdown threshold during femtosecond pulse exposure falls within one of two regimes. When the ratio of the maximum electric field from the outside to the inside of the nanorod is less then 7 (the absorption regime) the seed electrons are initiated by photo-thermal emission, and the wavelength dependence in the threshold of optical breakdown is the result of optical properties of the nanoparticle. When the ratio is greater than 7 (the near-field regime) more seed electrons are initiated by multiphoton ionization, and the wavelength dependence of the threshold of optical breakdown results from a combination of nanorod's optical properties and transitions in the order of multiphoton ionization. The findings of this study can guide the design of nanoparticle based optical breakdown applications. This analysis also deepens the understanding of nanoparticle-mediated laser induced breakdown for picosecond and femtosecond pulses at near infrared wavelengths. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The structure and dynamics of bubble-type vortex breakdown

Science.gov (United States)

Spall, R. E.; Ash, R. L.; Gatski, T. B.

1990-01-01

A unique discrete form of the Navier-Stokes equations for unsteady, three-dimensional, incompressible flow has been used to study vortex breakdown numerically. A Burgers-type vortex was introduced along the central axis of the computational domain, and allowed to evolve in space and time. By varying the strength of the vortex and the free stream axial velocity distribution, using a previously developed Rossby number criterion as a guide, the location and size of the vortex breakdown region was controlled. While the boundaries of the vortex breakdown bubble appear to be nominally symmetric, the internal flow field is not. Consequently, the mechanisms for mixing and entrainment required to sustain the bubble region are different from those suggested by earlier axisymmetric models. Results presented in this study, for a Reynolds number of 200, are in good qualitative agreement with higher Reynolds number experimental observations, and a variety of plots have been presented to help illuminate the fluid physics.

Proteomic investigation of protein profile changes and amino acid residue-level modification in cooked lamb longissimus thoracis et lumborum: The effect of roasting.

Science.gov (United States)

Yu, Tzer-Yang; Morton, James D; Clerens, Stefan; Dyer, Jolon M

2016-09-01

Protein modifications of meat cooked by typical dry-heat methods (e.g., roasting) are currently not well understood. The present study utilised a shotgun proteomic approach to examine the molecular-level effect of roasting on thin lamb longissimus thoracis et lumborum patties, in terms of changes to both the protein profile and amino acid residue side-chain modifications. Cooking caused aggregation of actin, myosin heavy chains and sarcoplasmic proteins. Longer roasting time resulted in significantly reduced protein extractability as well as protein truncation involving particularly a number of myofibrillar and sarcoplasmic proteins, e.g., 6-phosphofructokinase, beta-enolase, l-lactate dehydrogenase A chain, alpha-actinin-3, actin and possibly myosin heavy chains. Modifications that have potential influence on nutritional properties, including carboxyethyllysine and a potentially glucose-derived N-terminal Amadori compound, were observed in actin and myoglobin after roasting. This study provided new insights into molecular changes resulting from the dry-heat treatment of meat, such as commonly used in food preparation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurements of electron avalanche formation time in W-band microwave air breakdown

International Nuclear Information System (INIS)

Cook, Alan M.; Hummelt, Jason S.; Shapiro, Michael A.; Temkin, Richard J.

2011-01-01

We present measurements of formation times of electron avalanche ionization discharges induced by a focused 110 GHz millimeter-wave beam in atmospheric air. Discharges take place in a free volume of gas, with no nearby surfaces or objects. When the incident field amplitude is near the breakdown threshold for pulsed conditions, measured formation times are ∼0.1-2 μs over the pressure range 5-700 Torr. Combined with electric field breakdown threshold measurements, the formation time data shows the agreement of 110 GHz air breakdown with the similarity laws of gas discharges.

Measurements of electron avalanche formation time in W-band microwave air breakdown

Science.gov (United States)

Cook, Alan M.; Hummelt, Jason S.; Shapiro, Michael A.; Temkin, Richard J.

2011-08-01

We present measurements of formation times of electron avalanche ionization discharges induced by a focused 110 GHz millimeter-wave beam in atmospheric air. Discharges take place in a free volume of gas, with no nearby surfaces or objects. When the incident field amplitude is near the breakdown threshold for pulsed conditions, measured formation times are ˜0.1-2 μs over the pressure range 5-700 Torr. Combined with electric field breakdown threshold measurements, the formation time data shows the agreement of 110 GHz air breakdown with the similarity laws of gas discharges.

Antioxidant activity of pomegranate peel extract on lipid and protein oxidation in beef meatballs during frozen storage.

Science.gov (United States)

Turgut, Sebahattin Serhat; Işıkçı, Fatma; Soyer, Ayla

2017-07-01

Antioxidant effect of pomegranate peel extract (PE) to retard lipid and protein oxidation in beef meatballs was investigated during frozen storage at -18±1°C. Concentrated and freeze dried aqueous extract of pomegranate peel was incorporated into freshly prepared meatball mix at 0.5% and 1.0% concentrations, and compared with 0.01% butylated hydroxytoluene (BHT) and control (without any antioxidant). In PE treated samples, particularly in high PE concentration, peroxide, malondialdehyde and carbonyl formation, loss of total protein solubility and sulfhydryl groups were significantly lower than control after 6months of storage. A diminution of both myofibrillar (MP) and sarcoplasmic (SP) proteins of high molecular weight was detected after 6months of the storage according to gel electrophoresis patterns. The 1.0% PE led to maintain colour intensity (C) and hue (h°) value. The results from sensory analyses revealed that PE addition to meatballs was effective on preventing rancid odour formation. Addition of both 0.5 and 1% PE in meatballs reduced lipid and protein oxidation and improved sensory scores. These results indicated that PE was effective on retarding lipid and protein oxidations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical breakdown phenomena of dielectric elastomers

DEFF Research Database (Denmark)

Yu, Liyun; Mateiu, Ramona Valentina; Skov, Anne Ladegaard

2017-01-01

years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we focus on the chloro propyl functionalized silicone elastomers prepared in Madsen et al[2] and we investigate the electrical...

Blueprint for Breakdown: Three Mile Island and the Media before the Accident.

Science.gov (United States)

Friedman, Sharon M.

1981-01-01

Discusses media coverage of the Three Mile Island nuclear power plant before and during the disaster. Concludes that there was a communication breakdown prior to the accident. Outlines the causes and offers suggestions for avoiding similar breakdowns in the future. (JMF)

Predicting Flow Breakdown Probability and Duration in Stochastic Network Models: Impact on Travel Time Reliability

Energy Technology Data Exchange (ETDEWEB)

Dong, Jing [ORNL; Mahmassani, Hani S. [Northwestern University, Evanston

2011-01-01

This paper proposes a methodology to produce random flow breakdown endogenously in a mesoscopic operational model, by capturing breakdown probability and duration. Based on previous research findings that probability of flow breakdown can be represented as a function of flow rate and the duration can be characterized by a hazard model. By generating random flow breakdown at various levels and capturing the traffic characteristics at the onset of the breakdown, the stochastic network simulation model provides a tool for evaluating travel time variability. The proposed model can be used for (1) providing reliability related traveler information; (2) designing ITS (intelligent transportation systems) strategies to improve reliability; and (3) evaluating reliability-related performance measures of the system.

Metabolism of whole body protein in pregnant and non-pregnant gilts using 15N-glycine single-dose end-product method

International Nuclear Information System (INIS)

Wu De; Liu Huifang; Zhou Anguo; Wang Kangning; Yang Feng

2007-01-01

The metabolism of whole-body protein for pregnant and non-pregnant gilts was investigated using single-dose of 15 N-glycine end-product method. The results showed that there were no differences (P>0.05) in protein dynamic metabolism, amino acids utilization rate between pregnant and non-pregnant gilts at breeding. However, N flux, protein turnover rate, protein synthesis rate and breakdown rate of pregnant gilts were lower (P<0.05) than those of non-pregnant gilts at 30days after breeding, but the protein aggradiation's rate increased by 25% (P<0.05). During late gestation, N flux, protein turnover rate, protein synthesis rate and breakdown rate of pregnant sows were significantly increased (P<0.01), and protein aggradation's rate increased by 71.1%, compared with that of non-pregnant gilts. (authors)

Kinetic Simulations of Dense Plasma Focus Breakdown

Science.gov (United States)

Schmidt, A.; Higginson, D. P.; Jiang, S.; Link, A.; Povilus, A.; Sears, J.; Bennett, N.; Rose, D. V.; Welch, D. R.

2015-11-01

A dense plasma focus (DPF) device is a type of plasma gun that drives current through a set of coaxial electrodes to assemble gas inside the device and then implode that gas on axis to form a Z-pinch. This implosion drives hydrodynamic and kinetic instabilities that generate strong electric fields, which produces a short intense pulse of x-rays, high-energy (>100 keV) electrons and ions, and (in deuterium gas) neutrons. A strong factor in pinch performance is the initial breakdown and ionization of the gas along the insulator surface separating the two electrodes. The smoothness and isotropy of this ionized sheath are imprinted on the current sheath that travels along the electrodes, thus making it an important portion of the DPF to both understand and optimize. Here we use kinetic simulations in the Particle-in-cell code LSP to model the breakdown. Simulations are initiated with neutral gas and the breakdown modeled self-consistently as driven by a charged capacitor system. We also investigate novel geometries for the insulator and electrodes to attempt to control the electric field profile. The initial ionization fraction of gas is explored computationally to gauge possible advantages of pre-ionization which could be created experimentally via lasers or a glow-discharge. Prepared by LLNL under Contract DE-AC52-07NA27344.

Evaluation of methods for increasing vacuum breakdown strength

International Nuclear Information System (INIS)

Evans, R.D.; Cooke, C.M.; Berman, E.R.

1977-01-01

Research to determine the effectiveness of coated and gas shielded cathodes as a means of increasing vacuum breakdown strength under short pulse conditions is reported. A technique for rapidly evaluating large numbers of coatings on small electrodes at relatively low pulse voltage (120 kV or less) and methods for testing larger electrodes and fewer coatings at higher total voltage were developed. Experiments with gas shielded cathodes were also conducted. Results suggest that it may be possible to eliminate prebreakdown current and to double breakdown strength by applying a suitable coating to the cathode. Breakdown stresses in excess of 2 MV/cm were obtained in a 0.5 mm gap with sputtered coatings of alumina, Cr 2 O 3 , and several readily available epoxies. Electrodes two orders of magnitude greater in area were tested, and stresses approaching 1 MV/cm were measured in 5 mm gaps for several epoxies and for alumina. It has further been shown that, because similar trends occurred in the data from large and small experiments, it should be possible to screen potential coatings rapidly and effectively with minimum expenditure using a method similar to that employed for small electrodes at low pulse voltage

BAG3 directly interacts with mutated alphaB-crystallin to suppress its aggregation and toxicity.

Directory of Open Access Journals (Sweden)

Akinori Hishiya

Full Text Available A homozygous disruption or genetic mutation of the bag3 gene causes progressive myofibrillar myopathy in mouse and human skeletal and cardiac muscle disorder while mutations in the small heat shock protein αB-crystallin gene (CRYAB are reported to be responsible for myofibrillar myopathy. Here, we demonstrate that BAG3 directly binds to wild-type αB-crystallin and the αB-crystallin mutant R120G, via the intermediate domain of BAG3. Peptides that inhibit this interaction in an in vitro binding assay indicate that two conserved Ile-Pro-Val regions of BAG3 are involved in the interaction with αB-crystallin, which is similar to results showing BAG3 binding to HspB8 and HspB6. BAG3 overexpression increased αB-crystallin R120G solubility and inhibited its intracellular aggregation in HEK293 cells. BAG3 suppressed cell death induced by αB-crystallin R120G overexpression in differentiating C2C12 mouse myoblast cells. Our findings indicate a novel function for BAG3 in inhibiting protein aggregation caused by the genetic mutation of CRYAB responsible for human myofibrillar myopathy.

BAG3 Directly Interacts with Mutated alphaB-Crystallin to Suppress Its Aggregation and Toxicity

Science.gov (United States)

Hishiya, Akinori; Salman, Mortada Najem; Carra, Serena; Kampinga, Harm H.; Takayama, Shinichi

2011-01-01

A homozygous disruption or genetic mutation of the bag3 gene causes progressive myofibrillar myopathy in mouse and human skeletal and cardiac muscle disorder while mutations in the small heat shock protein αB-crystallin gene (CRYAB) are reported to be responsible for myofibrillar myopathy. Here, we demonstrate that BAG3 directly binds to wild-type αB-crystallin and the αB-crystallin mutant R120G, via the intermediate domain of BAG3. Peptides that inhibit this interaction in an in vitro binding assay indicate that two conserved Ile-Pro-Val regions of BAG3 are involved in the interaction with αB-crystallin, which is similar to results showing BAG3 binding to HspB8 and HspB6. BAG3 overexpression increased αB-crystallin R120G solubility and inhibited its intracellular aggregation in HEK293 cells. BAG3 suppressed cell death induced by αB-crystallin R120G overexpression in differentiating C2C12 mouse myoblast cells. Our findings indicate a novel function for BAG3 in inhibiting protein aggregation caused by the genetic mutation of CRYAB responsible for human myofibrillar myopathy. PMID:21423662

Double helix vortex breakdown in a turbulent swirling annular jet flow

Science.gov (United States)

Vanierschot, M.; Percin, M.; van Oudheusden, B. W.

2018-03-01

In this paper, we report on the structure and dynamics of double helix vortex breakdown in a turbulent annular swirling jet. Double helix breakdown has been reported previously for the laminar flow regime, but this structure has rarely been observed in turbulent flow. The flow field is investigated experimentally by means of time-resolved tomographic particle image velocimetry. Notwithstanding the axisymmetric nature of the time-averaged flow, analysis of the instantaneous three-dimensional (3D) vortical structures shows the existence of a vortex core along the central axis which breaks up into a double helix downstream. The winding sense of this double helix is opposite to the swirl direction (m =-2 ) and it is wrapped around a central vortex breakdown bubble. This structure is quite different from double helix breakdown found in laminar flows where the helix is formed in the wake of the bubble and not upstream. The double helix precesses around the central axis of the jet with a precessing frequency corresponding to a Strouhal number of 0.27.

Vortical flows over delta wings and numerical prediction of vortex breakdown

Science.gov (United States)

Ekaterinaris, J. A.; Schiff, Lewis B.

1990-01-01

Navier-Stokes solutions of subsonic vortical flow over a 75 deg sweep delta wing with a sharp leading edge are presented. The sensitivity of the solution to the numerical scheme is examined using both a partially upwind scheme and a scheme with central differencing in all directions. At moderate angles of attack, no vortex breakdown is observed, whereas the higher angle-of-attack cases exhibit breakdown. The effect of numerical grid density is investigated, and solutions that are obtained with various grid densities are compared with experimental data. An embedded grid approach is implemented to enable higher resolution in selected isolated flow regions, such as the leeward-side surface, the leading-edge vortical flow, and the vortex breakdown region.

Adaptive computations of flow around a delta wing with vortex breakdown

Science.gov (United States)

Modiano, David L.; Murman, Earll M.

1993-01-01

An adaptive unstructured mesh solution method for the three-dimensional Euler equations was used to simulate the flow around a sharp edged delta wing. Emphasis was on the breakdown of the leading edge vortex at high angle of attack. Large values of entropy, which indicate vortical regions of the flow, specified the region in which adaptation was performed. The aerodynamic normal force coefficients show excellent agreement with wind tunnel data measured by Jarrah, and demonstrate the importance of adaptation in obtaining an accurate solution. The pitching moment coefficient and the location of vortex breakdown are compared with experimental data measured by Hummel and Srinivasan, showing good agreement in cases in which vortex breakdown is located over the wing.

Facilitating breakdown in noble gases at near-atmospheric pressure using antennas

Energy Technology Data Exchange (ETDEWEB)

Sobota, A; Van Veldhuizen, E M; Haverlag, M [Eindhoven University of Technology, Department of Applied Physics, Postbus 513, 5600MB Eindhoven (Netherlands); Gendre, M F; Manders, F, E-mail: a.sobota@tue.nl [Philips Lighting, Mathildelaan 1, 5600JM Eindhoven (Netherlands)

2011-04-20

Electrical breakdown in near-atmospheric pressure noble gases requires voltages that are quite high, which is undesirable for a large number of possible applications. Metallic structures (antennas) were used on the outer side of the lamp burner to enhance the electric field locally while keeping the same potential difference across the electrodes. Optical and electrical measurements were performed in an argon or xenon atmosphere at 0.3 or 0.7 bar, with 4 or 7 mm between the electrode tips. We used rod-shaped tungsten electrodes of 0.6 mm in diameter. We found that both active and passive antennas facilitate breakdown, and we demonstrated the differences between the two types and their effects on the breakdown process.

Facilitating breakdown in noble gases at near-atmospheric pressure using antennas

International Nuclear Information System (INIS)

Sobota, A; Van Veldhuizen, E M; Haverlag, M; Gendre, M F; Manders, F

2011-01-01

Electrical breakdown in near-atmospheric pressure noble gases requires voltages that are quite high, which is undesirable for a large number of possible applications. Metallic structures (antennas) were used on the outer side of the lamp burner to enhance the electric field locally while keeping the same potential difference across the electrodes. Optical and electrical measurements were performed in an argon or xenon atmosphere at 0.3 or 0.7 bar, with 4 or 7 mm between the electrode tips. We used rod-shaped tungsten electrodes of 0.6 mm in diameter. We found that both active and passive antennas facilitate breakdown, and we demonstrated the differences between the two types and their effects on the breakdown process.

Experimental study of DC vacuum breakdown and application to high-gradient accelerating structures for CLIC

CERN Document Server

Shipman, Nicholas; Jones, Roger

2016-01-01

The compact linear collider (CLIC) is a leading candidate for the next generation high energy linear collider. As any breakdown would result in a partial or full loss of luminosity for the pulse in which it occurs, obtaining a low breakdown rate in CLIC accelerating structures is a critical requirement for the successful operation of the proposed collider. This thesis presents investigations into the breakdown phenomenon primarily in the low breakdown rate regime of interest to CLIC, performed using the CERN DC spark systems between 2011 and 2014. The design, construction and commissioning of several new pieces of hardware, as well as the development of improved techniques to measuring the inter-electrode gap distance are detailed. These hardware improvements were fundamental in enabling the exciting new experiments mentioned below, which in turn have provided significant additional insight into the phenomenon of breakdown. Experiments were performed to measure fundamental parameters of individual breakdowns...

Breakdown characteristics in DC spark experiments of copper focusing on purity and hardness

CERN Document Server

Yokoyama, Kazue; Higashi, Yasuo; Higo, Toshi; Matsumoto, Shuji; Santiago-Kern, Ana Rocia; Pasquino, Chiara; Calatroni, Sergio; Wuensch, Walter

2010-01-01

The breakdown characteristics related to the differences in purity and hardness were investigated for several types of copper using a DC spark test system. Three types of oxygen-free copper (OFC) materials, usual class 1 OFC 7-nine large-grain copper and 6-nine hot-isotropic-pressed (HIP) copper with/without diamond finish, were tested with the DC spark test system. The measurements of the beta, breakdown fields, and breakdown probability are presented and discussed in this paper.

Inhibitory effects of ethanol on phosphatidylinositol breakdown in pancreatic acini

International Nuclear Information System (INIS)

Towner, S.J.; Peppin, J.F.; Tsukamoto, H.

1986-01-01

Recently the physiological relationship between the phospholipid effect and secretagogue-induced cellular function has begun to be understood. In this study, the authors investigated acute and chronic effects of ethanol on phosphatidylinositol (PI) synthesis and breakdown in pancreatic acini. Five pairs of male Wistar rats were intragastrically infused for 30 days with high fat diet (25% total calories) plus ethanol or isocaloric dextrose. After intoxication, isolated in HEPES media, followed by 30 min incubation with CCK-8 (0, 100, 300 or 600 pM) and ethanol (0 or 100 mM). Acinar lipids were extracted and counted for labeled PI. Incorporation of 3 H-inositol into alcoholic acinar PI was reduced to 38.2% of that in controls. A percent maximal PI break down by CCK-8 was similar in the two groups (13-24% of basal). However, the magnitude of PI breakdown was markedly lower in alcoholic acini (482 vs 1081 dpm) due to the decreased PI synthesis rate. The presence of 100 mM ethanol in the media further inhibited the breakdown by 50% in this group. These results strongly indicate that chronic ethanol intoxication inhibits PI synthesis and breakdown in pancreatic acini, and that this inhibition can be potentiated by acute ethanol administration

Effect of RF Parameters on Breakdown Limits in High-Vacuum X-Band Structures

International Nuclear Information System (INIS)

Dolgashev, Valery A.

2003-01-01

RF breakdown is one of the major factors determining performance of high power rf components and rf sources. RF breakdown limits working power and produces irreversible surface damage. The breakdown limit depends on the rf circuit, structure geometry, and rf frequency. It is also a function of the input power, pulse width, and surface electric and magnetic fields. In this paper we discuss multi-megawatt operation of X-band rf structures at pulse width on the order of one microsecond. These structures are used in rf systems of high gradient accelerators. Recent experiments at Stanford Linear Accelerator Center (SLAC) have explored the functional dependence of breakdown limit on input power and pulse width. The experimental data covered accelerating structures and waveguides. Another breakdown limit of accelerating structures was associated with high magnetic fields found in waveguide-to-structure couplers. To understand and quantify these limits we simulated 3D structures with the electrodynamics code Ansoft HFSS and the Particle-In-Cell code MAGIC3D. Results of these simulations together with experimental data will be discussed in this paper

Degradation characteristics of 2G HTS tapes with respect to an electrical breakdown

International Nuclear Information System (INIS)

Kang, Jong O; Lee, On You; Mo, Young Kyu; Kim, Jun Il; Bang, Seung Min; Lee, Hong Seok; Kang, Hyoung Ku; Lee, Jae Hun; Jang, Cheol Yeong

2015-01-01

The electrical insulation design for a superconducting coil system is important for developing high voltage superconducting apparatuses. Also, the degraded characteristics of superconducting tapes due to an electrical breakdown should be considered for superconducting coils design. In this study, the degradation characteristics of 2G high temperature superconducting (HTS) tapes were studied with respect to electrical breakdown tests. The degradation tests of 2G HTS tapes were performed with various stabilizer materials. The degradation characteristics of 2G HTS tapes such as critical current(Ic) and index number were observed by performing electrical breakdown tests. It was found that the characteristics such as Ic and index number can be degraded by an electrical breakdown. Moreover, it was concluded that the degradation characteristics of 2G HTS tapes were affected by a stabilizer material and applied breakdown voltage. The cross sectional view of 2G HTS tapes was observed by using a scanning electron microscope (SEM). As results, it is found that the degradation characteristics of 2G HTS tapes are concerned with hardness and electrical resistivity of stabilizer layers

New method for determining avalanche breakdown voltage of silicon photomultipliers

International Nuclear Information System (INIS)

Chirikov-Zorin, I.

2017-01-01

The avalanche breakdown and Geiger mode of the silicon p-n junction is considered. A precise physically motivated method is proposed for determining the avalanche breakdown voltage of silicon photomultipliers (SiPM). The method is based on measuring the dependence of the relative photon detection efficiency (PDE rel ) on the bias voltage when one type of carriers (electron or hole) is injected into the avalanche multiplication zone of the p-n junction. The injection of electrons or holes from the base region of the SiPM semiconductor structure is performed using short-wave or long-wave light. At a low overvoltage (1-2 V) the detection efficiency is linearly dependent on the bias voltage; therefore, extrapolation to zero PDE rel value determines the SiPM avalanche breakdown voltage with an accuracy within a few millivolts. [ru

Rational design and evolutional fine tuning of Saccharomyces cerevisiae for biomass breakdown.

Science.gov (United States)

Hasunuma, Tomohisa; Ishii, Jun; Kondo, Akihiko

2015-12-01

Conferring biomass hydrolysis activity on yeast through genetic engineering has paved the way for the development of groundbreaking processes for producing liquid fuels and commodity chemicals from lignocellulosic biomass. However, the overproduction and misfolding of heterologous and endogenous proteins can trigger cellular stress, increasing the metabolic burden and retarding growth. Improving the efficiency of lignocellulosic breakdown requires engineering of yeast secretory pathway based on system-wide metabolic analysis as well as DNA constructs for enhanced cellulase gene expression with advanced molecular biology tools. Also, yeast is subjected to severe stress due to toxic compounds generated during lignocellulose pretreatment in consolidated saccharification and fermentation processes. The prospect for development of robust yeast strains makes combining evolutionary and rational engineering strategies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detection of Minerals in Green Leafy Vegetables Using Laser Induced Breakdown Spectroscopy

Science.gov (United States)

Shukla, P.; Kumar, R.; Raib, A. Kumar

2016-11-01

The distribution of minerals in different green leafy vegetables, such as spinach, chenopodium, chickpea, mustard, and fenugreek, was calculated using laser induced breakdown spectroscopy (LIBS). LIBS can provide an easy, reliable, efficient, low-cost, and in situ chemical analysis with a reasonable precision. In situ LIBS spectra in the range 200-500 nm were carried out using fresh leaves and leaves in the pellet form. As the spectra suggest, magnesium and calcium are present in each vegetable; however, the amount of them varies. It is observed that the amount of iron is maximal in spinach. The nutrition value of the plants was analyzed, and it was revealed that they are low in calories and fat and high in protein, fiber, iron, calcium, and phytochemicals.

Dynamic changes in the mouse skeletal muscle proteome during denervation-induced atrophy

Directory of Open Access Journals (Sweden)

Franziska Lang

2017-07-01

Full Text Available Loss of neuronal stimulation enhances protein breakdown and reduces protein synthesis, causing rapid loss of muscle mass. To elucidate the pathophysiological adaptations that occur in atrophying muscles, we used stable isotope labelling and mass spectrometry to quantify protein expression changes accurately during denervation-induced atrophy after sciatic nerve section in the mouse gastrocnemius muscle. Additionally, mice were fed a stable isotope labelling of amino acids in cell culture (SILAC diet containing 13C6-lysine for 4, 7 or 11 days to calculate relative levels of protein synthesis in denervated and control muscles. Ubiquitin remnant peptides (K-ε-GG were profiled by immunoaffinity enrichment to identify potential substrates of the ubiquitin-proteasomal pathway. Of the 4279 skeletal muscle proteins quantified, 850 were differentially expressed significantly within 2 weeks after denervation compared with control muscles. Moreover, pulse labelling identified Lys6 incorporation in 4786 proteins, of which 43 had differential Lys6 incorporation between control and denervated muscle. Enrichment of diglycine remnants identified 2100 endogenous ubiquitination sites and revealed a metabolic and myofibrillar protein diglycine signature, including myosin heavy chains, myomesins and titin, during denervation. Comparative analysis of these proteomic data sets with known atrogenes using a random forest approach identified 92 proteins subject to atrogene-like regulation that have not previously been associated directly with denervation-induced atrophy. Comparison of protein synthesis and proteomic data indicated that upregulation of specific proteins in response to denervation is mainly achieved by protein stabilization. This study provides the first integrated analysis of protein expression, synthesis and ubiquitin signatures during muscular atrophy in a living animal.

Optically reversible electrical soft-breakdown in wide-bandgap oxides—A factorial study

Science.gov (United States)

Zhou, Y.; Ang, D. S.; Kalaga, P. S.

2018-04-01

In an earlier work, we found that an electrical soft-breakdown region in wide-bandgap oxides, such as hafnium dioxide, silicon dioxide, etc., could be reversed when illuminated by white light. The effect is evidenced by a decrease in the breakdown leakage current, termed as a negative photoconductivity response. This finding raises the prospect for optical sensing applications based on these traditionally non-photo-responsive but ubiquitous oxide materials. In this study, we examine the statistical distribution for the rate of breakdown reversal as well as the influence of factors such as wavelength, light intensity, oxide stoichiometry (or oxygen content) and temperature on the reversal rate. The rate of breakdown reversal is shown to be best described by the lognormal distribution. Light in the range of ˜400-700 nm is found to have relatively little influence on the reversal rate. On the other hand, light intensity, oxygen content and temperature, each of them has a clear impact; a stronger light intensity, an oxide that is richer in oxygen content and a reduced temperature all speed up the reversal process substantially. These experimental results are consistent with the proposed phenomenological redox model involving photo-assisted recombination of the surrounding oxygen interstitials with vacancy defects in the breakdown path.

Method of making dielectric capacitors with increased dielectric breakdown strength

Science.gov (United States)

Ma, Beihai; Balachandran, Uthamalingam; Liu, Shanshan

2017-05-09

The invention is directed to a process for making a dielectric ceramic film capacitor and the ceramic dielectric laminated capacitor formed therefrom, the dielectric ceramic film capacitors having increased dielectric breakdown strength. The invention increases breakdown strength by embedding a conductive oxide layer between electrode layers within the dielectric layer of the capacitors. The conductive oxide layer redistributes and dissipates charge, thus mitigating charge concentration and micro fractures formed within the dielectric by electric fields.

Conditioning and breakdown phenomena in accelerator tubes

International Nuclear Information System (INIS)

Skorka, S.J.

1979-01-01

Important breakdown mechanisms in accelerator tubes are reviewed, and discharge phenomena in NEC tubes are deduced from the surface appearance of the electrodes and insulators of a used tube. Microphotos of these surfaces are shown

Skeletal muscle protein metabolism in the elderly: Interventions to counteract the 'anabolic resistance' of ageing

Directory of Open Access Journals (Sweden)

Phillips Stuart M

2011-10-01

Full Text Available Abstract Age-related muscle wasting (sarcopenia is accompanied by a loss of strength which can compromise the functional abilities of the elderly. Muscle proteins are in a dynamic equilibrium between their respective rates of synthesis and breakdown. It has been suggested that age-related sarcopenia is due to: i elevated basal-fasted rates of muscle protein breakdown, ii a reduction in basal muscle protein synthesis (MPS, or iii a combination of the two factors. However, basal rates of muscle protein synthesis and breakdown are unchanged with advancing healthy age. Instead, it appears that the muscles of the elderly are resistant to normally robust anabolic stimuli such as amino acids and resistance exercise. Ageing muscle is less sensitive to lower doses of amino acids than the young and may require higher quantities of protein to acutely stimulate equivalent muscle protein synthesis above rest and accrue muscle proteins. With regard to dietary protein recommendations, emerging evidence suggests that the elderly may need to distribute protein intake evenly throughout the day, so as to promote an optimal per meal stimulation of MPS. The branched-chain amino acid leucine is thought to play a central role in mediating mRNA translation for MPS, and the elderly should ensure sufficient leucine is provided with dietary protein intake. With regards to physical activity, lower, than previously realized, intensity high-volume resistance exercise can stimulate a robust muscle protein synthetic response similar to traditional high-intensity low volume training, which may be beneficial for older adults. Resistance exercise combined with amino acid ingestion elicits the greatest anabolic response and may assist elderly in producing a 'youthful' muscle protein synthetic response provided sufficient protein is ingested following exercise.

Endogenous proteolytic enzymes--a study of their impact on cod (Gadus morhua) muscle proteins and textural properties in a fermented product.

Science.gov (United States)

Yang, Fang; Rustad, Turid; Xu, Yanshun; Jiang, Qixing; Xia, Wenshui

2015-04-01

The aim of this study was to investigate endogenous proteolytic activities in a cod product and their impact on muscle proteins and textural properties during fermentation and storage. The result of specific proteolytic activities showed that cathepsins, especially cathepsin B, had the highest activities during fermentation and storage. SDS-PAGE indicated more degradation of myofibrillar proteins by cathepsin L than other proteases and that the hydrolysis by cathepsins was pronounced in the last stage of fermentation. Texture analysis showed that cathepsins had a negative impact on gel strength and this impact increased in the last stage of fermentation. However the product still had a firm texture. During storage (4 °C) for one week, no significant changes were seen in the gel strength. In conclusion, cathepsins had more impact on muscle proteins and textural properties than other proteases during fermentation but had little impact on gel strength during storage at 4 °C. Copyright © 2014 Elsevier Ltd. All rights reserved.

The anabolic potential of dietary protein intake on skeletal muscle is prolonged by prior light-load exercise

DEFF Research Database (Denmark)

Bechshøft, Rasmus; Dideriksen, Kasper; Reitelseder, Søren

2013-01-01

Hyperaminoacidemia stimulates myofibrillar fractional synthesis rate (myoFSR) transiently in resting skeletal muscle. We investigated whether light-load resistance exercise can extent this responsiveness....

Studying the Dynamics of Breakdown of Thin Horizontal Liquid Layers with Local Heating

Directory of Open Access Journals (Sweden)

Spesivtsev Serafim

2016-01-01

Full Text Available Experimental study of liquid layers breakdown when heated locally from the substrate side was made. Water and ethanol were used as working liquids with a layer thickness of 300 μm. Basic steps of the breakdown process were found and mean velocities of the dry spot formation were determined; the values are 0.06 mm/sec for ethanol and 5.15 mm/sec for water. The formation of residual layer over the hot-spot before the breakdown has been found for both liquids. The creation of a droplet cluster near the heating region is observed when using water as a working fluid. It was shown that evaporation is one of the general factors influencing the process of layer breakdown and dry spot formation as well as thermocapillary effect.

Investigation of vortex breakdown on delta wings using Navier-Stokes equations

Science.gov (United States)

Hsu, C.-H.; Liu, C. H.

1992-01-01

An efficient finite-difference scheme solving for the three-dimensional incompressible Navier-Stokes equations is described. Numerical simulations of vortex breakdown are then carried out for a sharp-edged delta wing and a round-edged double-delta wing at high Reynolds numbers. Computed results show that several major features of vortex breakdown are qualitatively in agreement with observations made in experiments.

Optical breakdown of helium in Bessel laser radiation beams

International Nuclear Information System (INIS)

Andreev, N E; Pleshanov, I V; Margolin, L Ya; Pyatnitskii, Lev N

1998-01-01

Numerical simulation is used to investigate the dynamics of formation of a helium plasma in Bessel beams, shaped by an axicon and a phase converter from a laser radiation pulse with Gaussian temporal and radial intensity profiles. The beam intensities at the breakdown threshold are determined as a function of the pulse duration for various radial field distributions in a beam characterised by Bessel functions of order m (m = 0 - 5). It is shown that in the investigated range of parameters the threshold intensity is independent of m. The temporal and spatial evolution of the resultant plasma, and the dependence of the plasma characteristics on the pulse parameters are considered. Conditions are found for the formation of tubular plasma channels in beams of orders m≥1. The adopted model of the optical breakdown of helium is shown to be satisfactory because of a good agreement between the results of calculations of the moment of breakdown in a zeroth-order Bessel beam and experimental results. (interaction of laser radiation with matter. laser plasma)

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Directory of Open Access Journals (Sweden)

Christian G. Parigger

2010-01-01

Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

The biochemical, textural and sensory properties of king scallop ...

African Journals Online (AJOL)

USER

2010-07-12

Jul 12, 2010 ... fluids and myofibrillar protein denaturation (Ca2+-ATPase activities in actomyosin extracts). ... much prized as food and its adductor muscle is offered to ..... and/or mechanical disruption of mitochondrial membranes.

Pre-breakdown light emission phenomena in low-pressure argon between parabolic electrodes

NARCIS (Netherlands)

Wagenaars, E.; Perriëns, N.W.B.; Brok, W.J.M.; Bowden, M.D.; Veldhuizen, van E.M.; Kroesen, G.M.W.

2006-01-01

An experimental study on pre-breakdown light emission in low-pressure argon gas was performed. In a pulsed discharge, pre-breakdown phenomena were observed for repetition rates between 100 and 2000 Hz and pulse duration of 100 ¿s. These phenomena were studied with time-resolved emission imaging

Research of Dielectric Breakdown Micro fluidic Sampling Chip

International Nuclear Information System (INIS)

Jiang, F.; Lei, Y.; Yu, J.

2013-01-01

Micro fluidic chip is mainly driven electrically by external electrode and array electrode, but there are certain disadvantages in both of ways, which affect the promotion and application of micro fluidic technology. This paper discusses a scheme that uses the conductive solution in a microchannel made by PDMS, replacing electrodes and the way of dielectric breakdown to achieve microfluidic chip driver. It could reduce the driving voltage and simplify the chip production process. To prove the feasibility of this method, we produced a micro fluidic chip used in PDMS material with the lithography technology and experimented it. The results showed that using the dielectric breakdown to achieve microfluidic chip driver is feasible, and it has certain application prospect.

Vortex-Breakdown-Induced Particle Capture in Branching Junctions.

Science.gov (United States)

Ault, Jesse T; Fani, Andrea; Chen, Kevin K; Shin, Sangwoo; Gallaire, François; Stone, Howard A

2016-08-19

We show experimentally that a flow-induced, Reynolds number-dependent particle-capture mechanism in branching junctions can be enhanced or eliminated by varying the junction angle. In addition, numerical simulations are used to show that the features responsible for this capture have the signatures of classical vortex breakdown, including an approach flow aligned with the vortex axis and a pocket of subcriticality. We show how these recirculation regions originate and evolve and suggest a physical mechanism for their formation. Furthermore, comparing experiments and numerical simulations, the presence of vortex breakdown is found to be an excellent predictor of particle capture. These results inform the design of systems in which suspended particle accumulation can be eliminated or maximized.

CANCER-PAthological breakdown of coherent energy states

Czech Academy of Sciences Publication Activity Database

Pokorný, Jiří; Pokorný, Jan; Kobilková, J.; Jandová, Anna; Vrba, J.; Vrba, J. jr.

2014-01-01

Roč. 9, č. 1 (2014), s. 115-133 ISSN 1793-0480 Institutional support: RVO:67985882 ; RVO:68378271 Keywords : breakdown of coherent states * Cancer electrodynamics * Warburg effect Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; BO - Biophysics (FZU-D)

The etiology of human age-related cataract. Proteins don't last forever.

Science.gov (United States)

Truscott, Roger J W; Friedrich, Michael G

2016-01-01

It is probable that the great majority of human cataract results from the spontaneous decomposition of long-lived macromolecules in the human lens. Breakdown/reaction of long-lived proteins is of primary importance and recent proteomic analysis has enabled the identification of the particular crystallins, and their exact sites of amino acid modification. Analysis of proteins from cataractous lenses revealed that there are sites on some structural proteins that show a consistently greater degree of deterioration than age-matched normal lenses. The most abundant posttranslational modification of aged lens proteins is racemization. Deamidation, truncation and crosslinking, each arising from the spontaneous breakdown of susceptible amino acids within proteins, are also present. Fundamental to an understanding of nuclear cataract etiology, it is proposed that once a certain degree of modification at key sites occurs, that protein-protein interactions are disrupted and lens opacification ensues. Since long-lived proteins are now recognized to be present in many other sites of the body, such as the brain, the information gleaned from detailed analyses of degraded proteins from aged lenses will apply more widely to other age-related human diseases. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of arsenic co-contamination on DDT breakdown and microbial activity

International Nuclear Information System (INIS)

Zwieten, Lukas van; Ayres, Matthew R.; Morris, Stephen G.

2003-01-01

Co-occurrence of arsenic and DDT in soil may result increased persistence of DDT. - The impacts of arsenic co-contamination on the natural breakdown of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) in soil are investigated in a study of 12 former cattle dip sites located in northeastern NSW, Australia. This study examines the relationship between the intrinsic breakdown of DDT to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), and the impacts of arsenic co-contamination on this breakdown. Between-site analysis demonstrated that arsenic at 2000 mg/kg gave a 50% reduction in the concentration of DDD compared to background arsenic of 5 mg/kg. Within-site analysis also showed the ratio of DDT:DDD increased in soils as arsenic concentrations increased. This within-site trend was also apparent with the DDT:DDE ratio, suggesting inhibition of DDT breakdown by arsenic co-contamination. Microbial activity was inhibited as residues of total DDTs and arsenic increased. Hence arsenic co-contamination and high concentrations of DDT in soil may result in an increased persistence of DDT in the environment studied

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

Energy Technology Data Exchange (ETDEWEB)

Siddabattuni, Sasidhar [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Schuman, Thomas P., E-mail: tschuman@mst.edu [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Dogan, Fatih [Missouri University of Science and Technology, Materials Science and Engineering Department, 1400N. Bishop Avenue, Rolla, MO 65409 (United States)

2011-11-15

Highlights: > A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. > A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T{sub g} measurements. > Composite T{sub g} was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. > A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. > The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity {approx}6.3 and at a 30 {mu}m thickness achieved a calculated energy density of 4.6 J/cm{sup 3}.

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

International Nuclear Information System (INIS)

Siddabattuni, Sasidhar; Schuman, Thomas P.; Dogan, Fatih

2011-01-01

Highlights: → A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. → A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T g measurements. → Composite T g was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. → A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. → The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity ∼6.3 and at a 30 μm thickness achieved a calculated energy density of 4.6 J/cm 3 .

Filament-induced remote surface ablation for long range laser-induced breakdown spectroscopy operation

International Nuclear Information System (INIS)

Rohwetter, Ph.; Stelmaszczyk, K.; Woeste, L.; Ackermann, R.; Mejean, G.; Salmon, E.; Kasparian, J.; Yu, J.; Wolf, J.-P.

2005-01-01

We demonstrate laser induced ablation and plasma line emission from a metallic target at distances up to 180 m from the laser, using filaments (self-guided propagation structures ∼ 100 μm in diameter and ∼ 5 x 10 13 W/cm 2 in intensity) appearing as femtosecond and terawatt laser pulses propagating in air. The remarkable property of filaments to propagate over a long distance independently of the diffraction limit opens the frontier to long range operation of the laser-induced breakdown spectroscopy technique. We call this special configuration of remote laser-induced breakdown spectroscopy 'remote filament-induced breakdown spectroscopy'. Our results show main features of filament-induced ablation on the surface of a metallic sample and associated plasma emission. Our experimental data allow us to estimate requirements for the detection system needed for kilometer-range remote filament-induced breakdown spectroscopy experiment

Thoughts on Limitation in the Use of Acoustic Sensors in RF Breakdown Localization

Energy Technology Data Exchange (ETDEWEB)

Le Pimpec, F

2004-08-02

X-band accelerator structures, meeting the Next Linear Collider (NLC) design requirements, have been found to suffer damage due to radio frequency (RF) breakdown when processed to high gradients. Improved understanding of these breakdown events is desirable for the development of structure designs, fabrication procedures, and processing techniques that minimize structure damage. Using an array of acoustic sensors, we have been able to pinpoint the location of individual breakdown events. However, a more accurate localization is required to understand the interaction between the phonon or the sound wave with the OFE copper.

Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

Science.gov (United States)

Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

2013-06-26

The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

Study of Dielectric Breakdown Performance of Transformer Oil Based Magnetic Nanofluids

Directory of Open Access Journals (Sweden)

Yuzhen Lv

2017-07-01

Full Text Available Research on the transformer oil-based nanofluids (NFs has been raised expeditiously over the past decade. Although, there is discrepancy in the stated results and inadequate understanding of the mechanisms of improvement of dielectric nanofluids, these nanofluids have emerged as a potential substitute of mineral oils as insulating and heat removal fluids for high voltage equipment. The transformer oil (TO based magnetic fluids (ferrofluids may be regarded as the posterity insulation fluids as they propose inspiring unique prospectus to improve dielectric breakdown strength, as well as heat transfer efficiency, as compared to pure transformer oils. In this work, transformer oil-based magnetic nanofluids (MNFs are prepared by dispersal of Fe3O4 nanoparticles (MNPs into mineral oil as base oil, with various NPs loading from 5 to 80% w/v. The lightning impulse breakdown voltages (BDV measurement was conducted in accordance with IEC 60897 by using needle to sphere electrodes geometry. The test results showed that dispersion of magnetic NPs may improve the insulation strength of MO. With the increment of NPs concentrations, the positive lightning impulse (LI breakdown strength of TO is first raised, up to the highest value at 40% loading, and then tends to decrease at higher concentrations. The outcomes of negative LI breakdown showed that BDV of MNFs, with numerous loadings, were inferior to the breakdown strength of pure MO. The 40% concentration of nanoparticles (optimum concentration was selected, and positive and negative LI breakdown strength was also further studied at different sizes (10 nm, 20 nm, 30 nm and 40 nm of NPs and different electrode gap distances. Augmentation in the BDV of the ferrofluids (FFs is primarily because of dielectric and magnetic features of Fe3O4 nanoaprticles, which act as electron scavengers and decrease the rate of free electrons produced in the ionization process. Research challenges and technical difficulties

Spectroscopic analysis of high protein nigella seeds (Kalonji) using laser-induced breakdown spectroscopy and inductively coupled plasma/optical emission spectroscopy

Science.gov (United States)

Rehan, Imran; Khan, M. Zubair; Ali, Irfan; Rehan, Kamran; Sultana, Sabiha; Shah, Sher

2018-03-01

The spectroscopic analysis of high protein nigella seeds (also called Kalonji) was performed using pulsed nanosecond laser-induced breakdown spectroscopy (LIBS) at 532 nm. The emission spectrum of Kalonji recorded with an LIBS spectrometer exposed the presence of various elements like Al, B, Ba, Ca, Cr, K, P, Mg, Mn, Na, Ni, S, Si, Cu, Fe, Ti, Sn, Sr, and Zn. The plasma parameters (electron temperature and electron density) were estimated using Ca-I spectral lines and their behavior were studied against laser irradiance. The electron temperature and electron density was observed to show an increasing trend in the range of 5802-7849 K, and (1.2-3.9) × 1017 cm- 3, respectively, in the studied irradiance range of (1.2-12.6) × 109 W/cm2. Furthermore, the effect of varying laser energy on the integrated signal intensities was also studied. The quantitative analysis of the detected elements was performed via the calibration curves drawn for all the observed elements through typical samples made in the known concentration in the Kalonji matrix, and by setting the concentration of P as the calibration. The validity of our LIBS findings was verified via comparison of the results with the concentration of every element find in Kalonji using the standard analytical tool like ICP/OES. The results acquired using LIBS and ICP/OES were found in fine harmony. Moreover, limit of detection was measured for toxic metals only.

Impulse breakdown of small air gap in electric field Part I: Influence ...

African Journals Online (AJOL)

The influence of barrier position on breakdown voltage in air dielectric has been investigated. Needle and Cone positive point electrodes were used and the effects of electrode curvature on barrier position for maximum breakdown voltage were compared, with air gap for the point to plane electrode fixed at 10 cm for all the ...

Work Breakdown Structure (WBS) Handbook

Science.gov (United States)

2010-01-01

The purpose of this document is to provide program/project teams necessary instruction and guidance in the best practices for Work Breakdown Structure (WBS) and WBS dictionary development and use for project implementation and management control. This handbook can be used for all types of NASA projects and work activities including research, development, construction, test and evaluation, and operations. The products of these work efforts may be hardware, software, data, or service elements (alone or in combination). The aim of this document is to assist project teams in the development of effective work breakdown structures that provide a framework of common reference for all project elements. The WBS and WBS dictionary are effective management processes for planning, organizing, and administering NASA programs and projects. The guidance contained in this document is applicable to both in-house, NASA-led effort and contracted effort. It assists management teams from both entities in fulfilling necessary responsibilities for successful accomplishment of project cost, schedule, and technical goals. Benefits resulting from the use of an effective WBS include, but are not limited to: providing a basis for assigned project responsibilities, providing a basis for project schedule development, simplifying a project by dividing the total work scope into manageable units, and providing a common reference for all project communication.

Collision and diffusion in microwave breakdown of nitrogen gas in and around microgaps

International Nuclear Information System (INIS)

Campbell, J. D.; Lenters, G. T.; Bowman, A.; Remillard, S. K.

2014-01-01

The microwave induced breakdown of N 2 gas in microgaps was modeled using the collision frequency between electrons and neutral molecules and the effective electric field concept. Low pressure breakdown at the threshold electric field occurs outside the gap, but at high pressures it is found to occur inside the microgap with a large threshold breakdown electric field corresponding to a very large electron oscillation amplitude. Three distinct pressure regimes are apparent in the microgap breakdown: a low pressure multipactor branch, a mid-pressure Paschen branch, both of which occur in the space outside the microgap, and a high pressure diffusion-drift branch, which occurs inside the microgap. The Paschen and diffusion-drift branches are divided by a sharp transition and each separately fits the collision frequency model. There is evidence that considerable electron loss to the microgap faces accompanies the diffusion-drift branch in microgaps

Fabrication of 4H-SiC Schottky barrier diodes with high breakdown voltages

CERN Document Server

Kum, B H; Shin, M W; Park, J D

1999-01-01

This paper discusses the fabrication and the breakdown characteristics of 4H-SiC Schottky barrier diodes (SBDs). Optimal processing conditions for the ohmic contacts were extracted using the transmission-line method (TLM) and were applied to the device fabrication. The Ti/4H-SiC SBDs with Si sub x B sub y passivation showed a maximum reverse breakdown voltage of 268 V with a forward current density as high as 70 mA/cm sup 2 at a forward voltage of 2 V. The breakdown of the Pt. 4H-SiC SBDs without any passivation occurred at near 110 V. It is concluded that the breakdown enhancement in the Ti/4H-SiC SBDs can be attributed to the passivation; otherwise, excess surface charge near the edge of the Schottky contact would lead to electric fields of sufficient magnitude to cause field emission.

Development of microwave-enhanced spark-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Ikeda, Yuji; Moon, Ahsa; Kaneko, Masashi

2010-01-01

We propose microwave-enhanced spark-induced breakdown spectroscopy with the same measurement and analysis processes as in laser-induced breakdown spectroscopy, but with a different plasma generation mechanism. The size and lifetime of the plasma generated can contribute to increased measurement accuracy and expand its applicability to industrial measurement, such as an exhaust gas analyzer for automobile engine development and its regulation, which has been hard to operate by laser at an engineering evaluation site. The use of microwaves in this application helps lower the cost, reduce the system size, and increase the ease of operation to make it commercially viable. A microwave frequency of 2.45 GHz was used to enhance the volume and lifetime of the plasma at atmospheric condition even at elevated pressure.

Study of vortex breakdown of F-106B by Euler code

Science.gov (United States)

Pao, Jenn Louh

1990-01-01

The 'Three-dimensional Euler Aerodynamic Method' (TEAM) is presently applied to the F-106B at subsonic speed, in order to examine the relationship between off- and on-surface flow features at angles-of-attack sufficiently great for the occurrence of vortex breakdown. Although TEAM's flow separation is triggered by numerical dissipation, the general trend of vortex-breakdown effect on computed lift characteristics is similar to extant wind tunnel results.

The effect of external visible light on the breakdown voltage of a long discharge tube

Science.gov (United States)

Shishpanov, A. I.; Ionikh, Yu. Z.; Meshchanov, A. V.

2016-06-01

The breakdown characteristics of a discharge tube with a configuration typical of gas-discharge light sources and electric-discharge lasers (a so-called "long discharge tube") filled with argon or helium at a pressure of 1 Torr have been investigated. A breakdown has been implemented using positive and negative voltage pulses with a linear leading edge having a slope dU/ dt ~ 10-107 V/s. Visible light from an external source (halogen incandescent lamp) is found to affect the breakdown characteristics. The dependences of the dynamic breakdown voltage of the tube on dU/ dt and on the incident light intensity are measured. The breakdown voltage is found to decrease under irradiation of the high-voltage anode of the tube in a wide range of dU/ dt. A dependence of the effect magnitude on the light intensity and spectrum is obtained. Possible physical mechanisms of this phenomenon are discussed.

Microcontroller based system for electrical breakdown time delay measurement in gas-filled devices.

Science.gov (United States)

Pejović, Milić M; Denić, Dragan B; Pejović, Momčilo M; Nešić, Nikola T; Vasović, Nikola

2010-10-01

This paper presents realization of a digital embedded system for measuring electrical breakdown time delay. The proposed system consists of three major parts: dc voltage supply, analog subsystem, and a digital subsystem. Any dc power source with the range from 100 to 1000 V can be used in this application. The analog subsystem should provide fast and accurate voltage switching on the testing device as well as transform the signals that represent the voltage pulse on the device and the device breakdown into the form suitable for detection by a digital subsystem. The insulated gate bipolar transistor IRG4PH40KD driven by TC429 MOSFET driver is used for high voltage switching on the device. The aim of a digital subsystem is to detect the signals from the analog subsystem and to measure the elapsed time between their occurrences. Moreover, the digital subsystem controls various parameters that influence time delay and provides fast data storage for a large number of measured data. For this propose, we used the PIC18F4550 microcontroller with a full-speed compatible universal serial bus (USB) engine. Operation of this system is verified on different commercial and custom made gas devices with different structure and breakdown mechanisms. The electrical breakdown time delay measurements have been carried out as a function of several parameters, which dominantly influence electrical breakdown time delay. The obtained results have been verified using statistical methods, and they show good agreement with the theory. The proposed system shows good repeatability, sensitivity, and stability for measuring the electrical breakdown time delay.

Microcontroller based system for electrical breakdown time delay measurement in gas-filled devices

Energy Technology Data Exchange (ETDEWEB)

Pejovic, Milic M.; Denic, Dragan B.; Pejovic, Momcilo M.; Nesic, Nikola T.; Vasovic, Nikola [Faculty of Electronic Engineering, University of Nis, Aleksandra Medvedeva 14, 18000 Nis (Serbia)

2010-10-15

This paper presents realization of a digital embedded system for measuring electrical breakdown time delay. The proposed system consists of three major parts: dc voltage supply, analog subsystem, and a digital subsystem. Any dc power source with the range from 100 to 1000 V can be used in this application. The analog subsystem should provide fast and accurate voltage switching on the testing device as well as transform the signals that represent the voltage pulse on the device and the device breakdown into the form suitable for detection by a digital subsystem. The insulated gate bipolar transistor IRG4PH40KD driven by TC429 MOSFET driver is used for high voltage switching on the device. The aim of a digital subsystem is to detect the signals from the analog subsystem and to measure the elapsed time between their occurrences. Moreover, the digital subsystem controls various parameters that influence time delay and provides fast data storage for a large number of measured data. For this propose, we used the PIC18F4550 microcontroller with a full-speed compatible universal serial bus (USB) engine. Operation of this system is verified on different commercial and custom made gas devices with different structure and breakdown mechanisms. The electrical breakdown time delay measurements have been carried out as a function of several parameters, which dominantly influence electrical breakdown time delay. The obtained results have been verified using statistical methods, and they show good agreement with the theory. The proposed system shows good repeatability, sensitivity, and stability for measuring the electrical breakdown time delay.

Microcontroller based system for electrical breakdown time delay measurement in gas-filled devices

International Nuclear Information System (INIS)

Pejovic, Milic M.; Denic, Dragan B.; Pejovic, Momcilo M.; Nesic, Nikola T.; Vasovic, Nikola

2010-01-01

This paper presents realization of a digital embedded system for measuring electrical breakdown time delay. The proposed system consists of three major parts: dc voltage supply, analog subsystem, and a digital subsystem. Any dc power source with the range from 100 to 1000 V can be used in this application. The analog subsystem should provide fast and accurate voltage switching on the testing device as well as transform the signals that represent the voltage pulse on the device and the device breakdown into the form suitable for detection by a digital subsystem. The insulated gate bipolar transistor IRG4PH40KD driven by TC429 MOSFET driver is used for high voltage switching on the device. The aim of a digital subsystem is to detect the signals from the analog subsystem and to measure the elapsed time between their occurrences. Moreover, the digital subsystem controls various parameters that influence time delay and provides fast data storage for a large number of measured data. For this propose, we used the PIC18F4550 microcontroller with a full-speed compatible universal serial bus (USB) engine. Operation of this system is verified on different commercial and custom made gas devices with different structure and breakdown mechanisms. The electrical breakdown time delay measurements have been carried out as a function of several parameters, which dominantly influence electrical breakdown time delay. The obtained results have been verified using statistical methods, and they show good agreement with the theory. The proposed system shows good repeatability, sensitivity, and stability for measuring the electrical breakdown time delay.

Breakdown and bad luck in Biblis

International Nuclear Information System (INIS)

Randow, G. von.

1994-01-01

Five minor breakdowns within a month have heated up the dispute between the ministries of the environment of the Federation and the Land of Hesse. Biblis A is to be shut down at all costs. As yet, however, the Hessian Ministry of the Environment has not solved the question of how to compensate the power cut. (DG) [de

Formation and breakdown of adenosine in the heart : investigations on myocardial purine metabolismen

NARCIS (Netherlands)

P.W. Achterberg (Peter)

1986-01-01

textabstractAdenosine, a strong coronary vasodilator, is a breakdown product of the myocardial high-energy phosphate ATP. ATP serves as the direct energy source for contraction of the heart. Chapter 1 of this thesis gives a general introduction on contractility dependent ATP-breakdown, the

MICROBIAL COLONIZATION, RESPIRATION, AND BREAKDOWN OF MAPLE LEAVES ALONG A STREAM-MARSH CONTINUUM

Science.gov (United States)

Breakdown rates, macroinvertebrate and bacterial colonization, and microbial respiration were measured on decaying maple (Acer saccharum) leaves at three sites along a stream-marsh continuum. Breakdown rates (-k+-SE) were 0.0284+-0.0045 d-1 for leaves in a high-gradient, non-tida...

Vortex Breakdown Generated by off-axis Bifurcation in a cylinder with rotating covers

DEFF Research Database (Denmark)

Bisgaard, Anders; Brøns, Morten; Sørensen, Jens Nørkær

2006-01-01

Vortex breakdown of bubble type is studied for the flow in a cylinder with rotating top and bottom covers. For large ratios of the angular velocities of the covers, we observe numerically that the vortex breakdown bubble in the steady regime may occur through the creation of an off-axis vortex ring....... This scenario does not occur in existing bifurcation theory based on a simple degeneracy in the flow field. We extend the theory to cover a non-simple degeneracy, and derive the associated bifurcation diagrams. We show that the vortex breakdown scenario involving a vortex ring can be explained from this theory...

Dispersion of breakdown voltage of liquid helium

International Nuclear Information System (INIS)

Ishii, Itaru; Noguchi, Takuya

1978-01-01

As for the electrical insulation characteristics of liquid helium, the discrepancy among the measured values by each person is very large even in the fundamental DC breakdown voltage in uniform electric field. The dispersion of experimental values obtained in the experiments by the same person is also large. Hereafter, the difference among the mean values obtained by each experimenter will be referred to as ''deviation of mean values'', and the dispersion of measured values around the mean value obtained by the same person as ''deviation around the man value''. The authors have mainly investigated on the latter experimentally. The cryostat was made of stainless steel, and the innermost helium chamber was of 500 mm I.D. and approximately 1200 mm deep. The high voltage electrode was of brass sphere of 25 mm diameter, and the low voltage electrode was of brass plate. The experiment was conducted for liquid helium boiling at 4.2 K and 1 atm, and the breakdown voltage and time lag were measured by applying the approximately square wave impulses of fast rise and long tail, ramp and DC voltages. The cause of the deviation of mean values may be the presence of impurity particles or the effect of electrode shape. As for the deviation around the mean value, the dispersion is large, and its standard deviation may amount to 10 to 20% of the man value. The dispersion is not due to the statistical time lag, but is due to parameters that vary with breakdown. (Wakatsuki, Y.)

Vortex breakdown of compressible swirling flows in a pipe

Science.gov (United States)

Lee, Harry; Rusak, Zvi; Wang, Shixiao

2017-11-01

The manifold of branches of steady and axisymmetric states of compressible subsonic swirling flows in a finite-length straight circular pipe are developed. The analysis is based on Rusak et al. (2015) nonlinear partial differential equation for the solution of the flow stream function in terms of the inlet flow total enthalpy, entropy and circulation functions. This equation reflects the complicated thermo-physical interactions in the flows. The flow problem is solved numerically using a finite difference approach with a penalty procedure for identifying vortex breakdown and wall-separation states. Several types of solutions are found and used to form the bifurcation diagram of steady compressible flows with swirl as the inlet swirl level is increased at a fixed inlet Mach number. Results are compared with predictions from the global analysis approach of Rusak et al. (2015). The computed results provide theoretical predictions of the critical swirl levels for the first appearance of vortex breakdown states as a function of the inlet Mach number. The shows the delay in the appearance of breakdown with increase of the inlet axial flow Mach number in the subsonic range of operation.

Surrogate decision makers' perspectives on preventable breakdowns in care among critically ill patients: A qualitative study.

Science.gov (United States)

Fisher, Kimberly A; Ahmad, Sumera; Jackson, Madeline; Mazor, Kathleen M

2016-10-01

To describe surrogate decision makers' (SDMs) perspectives on preventable breakdowns in care among critically ill patients. We screened 70 SDMs of critically ill patients for those who identified a preventable breakdown in care, defined as an event where the SDM believes something "went wrong", that could have been prevented, and resulted in harm. In-depth interviews were conducted with SDMs who identified an eligible event. 32 of 70 participants (46%) identified at least one preventable breakdown in care, with a total of 75 discrete events. Types of breakdowns involved medical care (n=52), communication (n=59), and both (n=40). Four additional breakdowns were related to problems with SDM bedside access to the patient. Adverse consequences of breakdowns included physical harm, need for additional medical care, emotional distress, pain, suffering, loss of trust, life disruption, impaired decision making, and financial expense. 28 of 32 SDMs raised their concerns with clinicians, yet only 25% were satisfactorily addressed. SDMs of critically ill patients frequently identify preventable breakdowns in care which result in harm. An in-depth understanding of the types of events SDMs find problematic and the associated harms is an important step towards improving the safety and patient-centeredness of healthcare. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Energetic high-voltage breakdowns in vacuum over a large gap for ITER neutral beam accelerator

Energy Technology Data Exchange (ETDEWEB)

Villecroze, F., E-mail: Frederic.villecroze@cea.fr [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Christin, L.; Esch, H.P.L. de; Simonin, A. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Schunke, B.; Svensson, L.; Hemsworth, R.; Boilson, D. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

2013-10-15

Highlights: ► We performed energetic high voltage breakdowns up to 370 kV with a stored energy of 1 kJ. ► No breakdowns at 200 kV could be produced over a gap of 85 mm using 100 cm{sup 2} copper electrodes. ► Electrodes damage was visible after the experiment. ► The number of arcs impacts is orders of magnitude above the number of breakdowns. -- Abstract: CEA has undertaken tests to study the resilience of copper electrodes in vacuum against energetic high-voltage breakdowns using external capacitors to provide the energy. Earlier tests succeeded in dissipating a maximum of 150 J in a 30 mm gap, limited by the equivalent series resistance (ESR) in the external capacitors. Using new ones with an ESR that is a factor of 10 lower it was unsuccessfully tried to produce breakdowns at 200 kV over the 85 mm gap, despite the use of a UV flash lamp and a “field enhancement ring” (FER) that locally increased the electric field on the cathode by 50%. Consequently, the breakdowns had to be produced by raising the voltage to 300–350 kV while maintaining the gap at 85 mm. During these tests, single breakdowns dissipated up to 1140 J in the 85 mm vacuum gap. Inspection of the electrodes revealed that substantial amounts of copper appear have been evaporated from the anode and deposited on to the cathode. Also electrode deconditioning occurred.

PIV Measurements for Validation of Self-induction Theory of Vortex Breakdown

Science.gov (United States)

Thompson, Brad; Dabiri, Dana

2005-11-01

THE PROBLEM: Tail buffeting is a severe operational and maintenance problem in twin-tailed aircraft. Tail buffeting is driven by aerodynamic forces resulting from the wing leading edge produced concentrated vortices and their subsequent abrupt breakdown and radial expansion. The expansion leads to large-diameter helical vortices, which impose lateral forces on the tails. Various brute-force, empirical approaches have provided some ad-hoc fixes, but poor understanding of the underlying physics prevents effective design solutions. It is not yet possible to design buffet-free aircraft from first principles. Preliminary work offers a unique explanation for vortex breakdown called the azimuthal vorticity gradient theory ...(Cain 2001). This paper will present and establish experimental evidence using DPIV to validate this recent theory. Cain, C. B. (2001). The Self-Induction Theory of Vortex Breakdown. Aeronautics Dept. Seattle, WA, University of Washington. Master Thesis.

Polymorphism of calpastatin gene in Arabic sheep using PCR- RFLP

African Journals Online (AJOL)

STORAGESEVER

2008-08-04

Aug 4, 2008 ... Calpastatin has been known as candidate gene in muscle growth efficiency and ... population, AA, AB, BB genotype have been identified with the 70.27, .... of cimaterol on rabbit growth and myofibrillar protein degradation.

Electric breakdown of high polymer insulating materials at cryogenic temperature

International Nuclear Information System (INIS)

Kim, Sanhyon; Yoshino, Katsumi

1985-01-01

Cryogenic properties : temperature dependence of E sub(b) and effects of media upon E sub(b) were investigated on several high polymers. Temperature conditions were provided by liquid He (4.2 K), liquid N 2 (77 K) and cryogen (dry ice-methyl alcohol, 194 K). Silicone oil was used also at ambient temperature and elevated temperature. Polymer film coated with gold by vacuum evaporation was placed in cryostat, and high tension from pulse generator was applied to the film. Dielectric breakdowns were detected by oscilloscope and observed visually. The results of experiment are summerized as follow. (1) E sub(b) of film in He is affected by medium remarkably, and covering with 3-methyl pentane is effective for increasing E sub(b). (2) Temperature dependence of E sub(b) was not recognized in cryogenic temperature below liquid N 2 . (3) Temperature characteristic of E sub(b) changes considerably at the critical temperature T sub(c), and T sub(c) is dependent on material. (4) Strength against dielectric breakdown under cryogenic temperature is not affected by bridging caused by irradiation of electron beam. (5) Dielectric breakdown is thought to be caused by electronic process such as electron avalanche. Consequently, for designing insulation for the temperature below liquid He, insulation design for liquid N 2 is thought to be sufficient. However, the degradation and breakdown by mechanical stress under cryogenic temperature must be taken into consideration. (Ishimitsu, A.)

Blackbody Emission from Laser Breakdown in High-Pressure Gases

Science.gov (United States)

Bataller, A.; Plateau, G. R.; Kappus, B.; Putterman, S.

2014-08-01

Laser induced breakdown of pressurized gases is used to generate plasmas under conditions where the atomic density and temperature are similar to those found in sonoluminescing bubbles. Calibrated streak spectroscopy reveals that a blackbody persists well after the exciting femtosecond laser pulse has turned off. Deviation from Saha's equation of state and an accompanying large reduction in ionization potential are observed at unexpectedly low atomic densities—in parallel with sonoluminescence. In laser breakdown, energy input proceeds via excitation of electrons whereas in sonoluminescence it is initiated via the atoms. The similar responses indicate that these systems are revealing the thermodynamics and transport of a strongly coupled plasma.

Dye visualization near a three-dimensional stagnation point: application to the vortex breakdown bubble

DEFF Research Database (Denmark)

Brøns, Morten; Thompson, M. C.; Hourigan, K.

2009-01-01

flows are typically visualized. Predictions based on the model are made for the steady vortex breakdown bubble in a torsionally driven cylinder and compared with computational fluid dynamics predictions and experimental observations. Previous experimental observations using tracer visualization...... techniques have suggested that even for low-Reynolds-number flows, the steady vortex breakdown bubble in a torsionally driven cylinder is not axisymmetric and has an inflow/outflow asymmetry at its tail. Recent numerical and theoretical studies show that the asymmetry of the vortex breakdown bubble......, and consequently its open nature, can be explained by the very small imperfections that are present in any experimental rig. Distinct from this, here it is shown that even for a perfectly axisymmetric flow and breakdown bubble, the combined effect of dye diffusion and the inevitable small errors in the dye...

Investigation of multipactor breakdown in communication satellite

Indian Academy of Sciences (India)

Multipactor breakdown or multipactor discharge is a form of high frequency discharge that may occur in microwave components operating at very low pressures. Some RF components of multi-channel communication satellites have co-axial geometry and handle high RF power under near-vacuum conditions.

Computational fluid-dynamic model of laser-induced breakdown in air

International Nuclear Information System (INIS)

Dors, Ivan G.; Parigger, Christian G.

2003-01-01

Temperature and pressure profiles are computed by the use of a two-dimensional, axially symmetric, time-accurate computational fluid-dynamic model for nominal 10-ns optical breakdown laser pulses. The computational model includes a kinetics mechanism that implements plasma equilibrium kinetics in ionized regions and nonequilibrium, multistep, finite-rate reactions in nonionized regions. Fluid-physics phenomena following laser-induced breakdown are recorded with high-speed shadowgraph techniques. The predicted fluid phenomena are shown by direct comparison with experimental records to agree with the flow patterns that are characteristic of laser spark decay

Impact of the Fenton process in meat digestion as assessed using an in vitro gastro-intestinal model.

Science.gov (United States)

Oueslati, Khaled; de La Pomélie, Diane; Santé-Lhoutellier, Véronique; Gatellier, Philippe

2016-10-15

The production of oxygen free radicals catalysed by non-haem iron was investigated in an in vitro mimetic model of the digestive tract using specific chemical traps. Superoxide radicals (O2(∗-)) and their protonated form (hydroperoxyl radicals, HO2(∗)) were detected by the reduction of nitroblue tetrazolium into formazan, and hydroxyl radicals (OH(∗)) were detected by the hydroxylation of terephthalate. Under gastric conditions, O2(∗-)/HO2(∗) were detected in higher quantity than OH(∗). Increasing the pH from 3.5 to 6.5 poorly affected the kinetics of free radical production. The oxidations generated by these free radicals were estimated on myofibrils prepared from pork rectus femoris muscle. Myofibrillar lipid and protein oxidation increased with time and oxidant concentration, with a negative impact on the digestibility of myofibrillar proteins. Plant food antioxidants considerably decreased free radical production and lipid oxidation but not protein oxidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of high pressure on physicochemical properties of meat.

Science.gov (United States)

Buckow, Roman; Sikes, Anita; Tume, Ron

2013-01-01

The application of high pressure offers some interesting opportunities in the processing of muscle-based food products. It is well known that high-pressure processing can prolong the shelf life of meat products in addition to chilling but the pressure-labile nature of protein systems limits the commercial range of applications. High pressure can affect the texture and gel-forming properties of myofibrillar proteins and, hence, has been suggested as a physical and additive-free alternative to tenderize and soften or restructure meat and fish products. However, the rate and magnitude at which pressure and temperature effects take place in muscles are variable and depend on a number of circumstances and conditions that are still not precisely known. This review provides an overview of the current knowledge of the effects of high pressure on muscle tissue over a range of temperatures as it relates to meat texture, microstructure, color, enzymes, lipid oxidation, and pressure-induced gelation of myofibrillar proteins.

Phenylalanine isotope pulse method to measure effect of sepsis on protein breakdown and membrane transport in the pig.

Science.gov (United States)

Ten Have, Gabriella A M; Engelen, Mariëlle P K J; Wolfe, Robert R; Deutz, Nicolaas E P

2017-06-01

The primed-continuous (PC) phenylalanine (Phe) stable isotope infusion methodology is often used as a proxy for measuring whole body protein breakdown (WbPB) in sepsis. It is unclear if WbPB data obtained by an easy-to-use single IV Phe isotope pulse administration (PULSE) are comparable to those by PC. Compartmental modeling with PULSE could provide us more insight in WbPB in sepsis. Therefore, in the present study, we compared PULSE with PC as proxy for WbPB in an instrumented pig model with Pseudomonas aeruginosa- induced severe sepsis (Healthy: n = 9; Sepsis: n = 13). Seventeen hours after sepsis induction, we compared the Wb rate of appearance (WbR a ) of Phe obtained by PC (L-[ ring - 13 C 6 ]Phe) and PULSE (L-[ 15 N]Phe) in arterial plasma using LC-MS/MS and (non)compartm e ntal modeling. PULSE-WbR a was highly correlated with PC-WbR a ( r  = 0.732, P sepsis (Healthy: 3,378 ± 103; Sepsis: 4,333 ± 160 nmol·kg BW -1 ·min -1 , P = 0.0002). With PULSE, sepsis was characterized by an increase of the metabolic shunting (Healthy: 3,021 ± 347; Sepsis: 4,233 ± 344 nmol·kg BW -1 ·min -1 , P = 0.026). Membrane transport capacity was the same. Both PC and PULSE methods are able to assess changes in WbR a of plasma Phe reflecting WbPB changes with high sensitivity, independent of the (patho)physiological state. The easy-to-use (non)compartmental PULSE reflects better the real WbPB than PC. With PULSE compartmental analysis, we conclude that the membrane transport capacity for amino acids is not compromised in severe sepsis. Copyright © 2017 the American Physiological Society.

Factors that Influence RF Breakdown in Antenna Systems

Science.gov (United States)

Caughman, J. B. O.; Baity, F. W.; Rasmussen, D. A.; Aghazarian, M.; Castano Giraldo, C. H.; Ruzic, David

2007-11-01

One of the main power-limiting factors in antenna systems is the maximum voltage that the antenna or vacuum transmission line can sustain before breaking down. The factors that influence RF breakdown are being studied in a resonant 1/4-wavelength section of vacuum transmission line terminated with an open circuit electrode structure. Breakdown can be initiated via electron emission by high electric fields and by plasma formation in the structure, depending on the gas pressure. Recent experiments have shown that a 1 kG magnetic field can influence plasma formation at pressures as low as 8x10-5 Torr at moderate voltage levels (LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725. Work supported by USDOE with grant DE-FG02-04ER54765

Microemulsion systems applied to breakdown petroleum emulsions

Energy Technology Data Exchange (ETDEWEB)

Neuma de Castro Dantas, Tereza; Avelino Dantas Neto, Afonso; Ferreira Moura, Everlane [Deptos de Quimica e Eng. Quimica, Universidade Federal do Rio Grande do Norte, Campus Universitario s/n, 59072.970, Natal/RN Campinas (Brazil)

2001-12-29

Microemulsion systems obtained using commercial surfactants with demulsifier and emulsion prevention properties have been employed to break down Brazilian crude water-in-oil (W/O) emulsions. These crude oils were supplied by the Brazilian oil company-PETROBRAS-and were characterized by the different Balance sheet of Sediment and Water (BSW) values of 48%, 36%, and 32%. The microemulsion systems formed in this study were composed of an aqueous phase (HCl 5.2% solution); an oil phase (toluene); a cosurfactant/surfactant (C/S) phase (isopropyl alcohol (C)/surfactants (S) with a ratio C/S of 9.0). The microemulsion efficiency to break down oil emulsions was evaluated by a direct contact method between the microemulsions and crude (W/O) emulsions. The Scheffe net statistical planning for mixtures was used to relate the component mass fractions to the relative breakdown of petroleum emulsions. The best composition of the microemulsion system for the complete breakdown of oil emulsions with high BSW values had the lowest C/S phase percentage.

Breakdown conditioning of copper, CuZr and GlidCop® : effect of mechanical surface treatments

CERN Document Server

Ramsvik, T; Calatroni, S; Taborelli, M; CERN. Geneva. TS Department

2007-01-01

Motivated by the need of novel materials for the CLIC accelerating structures to resist mechanical fatigue, the copper based metals Copper Zirconium C15000 (CuZr) and GlidCop® Al-15 C15715 have been investigated by DC breakdown measurements, and compared with commercially pure Oxygen-free Copper C10100 (Cu-OFE). In all three cases the saturated breakdown fields (Esat) are similar, despite significant differences in their tensile strengths. In addition, the choice of mechanical surface preparation techniques influences the final breakdown characteristics. For both CuZr and GlidCop® immediate conditioning takes place when the surfaces are prepared by milling. For electro discharge machined (EDM) surfaces, however, several breakdown events are needed to obtain saturation. Specifically, for EDM treated CuZr and GlidCop®, ~50 and ~200 breakdown events are required to reach Esat.

Dynamic of microwave breakdown in the localized places of transmitting line driving by Cherenkov-type oscillator

Science.gov (United States)

Xie, Jialing; Chen, Changhua; Chang, Chao; Wu, Cheng; Shi, Yanchao; Cao, Yibing; Song, Zhimin; Zhang, Yuchuan

2018-02-01

A breakdown cavity is designed to study the breakdown phenomena of high-power microwaves in transmission waveguides. The maximum electric field within the cavity varies in amplitude from 400 kV/cm to 1.8 MV/cm and may surpass breakdown thresholds. The breakdown cavities were studied in particle-in-cell simulations and experiments, the results of which yielded waveforms that were consistent. The experimental results indicate that the microwave pulse does not shorten, and the amplitude of the electric field does not fall below 800 kV/cm. Moreover, large numbers of electrons are not emitted in microwaves below 670 kV/cm at 9.75 GHz frequency and 25-ns pulse width transmitted in stainless steel waveguides. The radiation waveforms of breakdown cavity with different materials are compared in experiments, with titanium material performing better.

rf conditioning and breakdown analysis of a traveling wave linac with collinear load cells

Science.gov (United States)

Chen, Qushan; Hu, Tongning; Qin, Bin; Xiong, Yongqian; Fan, Kuanjun; Pei, Yuanji

2018-04-01

Huazhong University of Science and Technology (HUST) has built a compact linac-based terahertz free electron laser (THz-FEL) prototype. In order to achieve compact structure, the linac uses collinear load cells instead of conventional output coupler to absorb remanent power at the end of linac. The new designed structure is confronted with rf breakdown problem after a long time conditioning process, so we tried to figure out the breakdown site in the linac. Without transmitted signal, we propose two methods to analyze the breakdown site mainly based on the forward and the reflected power signals. One method focuses on the time relationship of the two signals while the other focuses on the amplitude. Both the two methods indicate the breakdown events happened at the end of the linac and more likely in the first or the second load cell.

rf conditioning and breakdown analysis of a traveling wave linac with collinear load cells

Directory of Open Access Journals (Sweden)

Qushan Chen

2018-04-01

Full Text Available Huazhong University of Science and Technology (HUST has built a compact linac-based terahertz free electron laser (THz-FEL prototype. In order to achieve compact structure, the linac uses collinear load cells instead of conventional output coupler to absorb remanent power at the end of linac. The new designed structure is confronted with rf breakdown problem after a long time conditioning process, so we tried to figure out the breakdown site in the linac. Without transmitted signal, we propose two methods to analyze the breakdown site mainly based on the forward and the reflected power signals. One method focuses on the time relationship of the two signals while the other focuses on the amplitude. Both the two methods indicate the breakdown events happened at the end of the linac and more likely in the first or the second load cell.

Delayed detached-eddy simulation of vortex breakdown over a 70 .deg. delta wing

International Nuclear Information System (INIS)

Son, Mi So; Sa, Jeong Hwan; Park, Soo Hyung; Byun, Yung Hwan; Cho, Kum Won

2015-01-01

To investigate the vortex breakdown over the ONERA70 delta wing at an angle-of-attack of 27 .deg., unsteady simulations were performed using Reynolds-averaged Navier-Stokes and Spalart-Allmaras delayed detached-eddy simulations. A low-diffusive preconditioned Roe scheme with third-order MUSCL interpolation scheme was applied, along with second-order dual-time stepping combined with diagonalized alternating direction implicit method for unsteady simulation. Vortex breakdown was investigated through an examination of total pressure loss, axial velocity, and axial vorticity around the primary vortex. Delayed dtached-eddy simulation provided good agreement with experimental data and predicted all physical phenomena related to vortex breakdown well.

Interleukin-6 markedly decreases skeletal muscle protein turnover and increases nonmuscle amino acid utilization in healthy individuals

DEFF Research Database (Denmark)

van Hall, Gerrit; Steensberg, Adam; Fischer, Christian

2008-01-01

CONTEXT: IL-6 is a key modulator of immune function and suggested to be involved in skeletal muscle wasting as seen in sepsis. OBJECTIVE: Our objective was to determine the role of IL-6 in human in vivo systemic and skeletal muscle amino acid metabolism and protein turnover. SUBJECTS AND METHODS...... synthesis was more suppressed than breakdown, causing a small increase in net muscle protein breakdown. Furthermore, rhIL-6 decreased arterial amino acid concentration with 20-40%, despite the increase net release from muscle. CONCLUSIONS: We demonstrated that IL-6 profoundly alters amino acid turnover....... A substantial decrease in plasma amino acids was observed with a concomitant 50% decrease in muscle protein turnover, however, modest increase in net muscle degradation. We hypothesize that the profound reduction in muscle protein turnover and modest increase in net degradation are primarily caused...

Energetic breakdowns and voltage hold-off between copper electrodes in vacuum

International Nuclear Information System (INIS)

Bottiglioni, F.; Bussac, J.P.

1980-10-01

In high power neutral beam injections, used for thermonuclear research, very high ion currents are extracted from large area ion sources, using an assembly of three or four extraction grids. The extraction system must be very reliable and unaffected by breakdowns that may occur between grids. The aim of the experiments described here, is to infer some empirical laws allowing to dimension the ion sources grid gaps and to assess what energy in the breakdowns leads to irreversible damages

[Study on physical deviation factors on laser induced breakdown spectroscopy measurement].

Science.gov (United States)

Wan, Xiong; Wang, Peng; Wang, Qi; Zhang, Qing; Zhang, Zhi-Min; Zhang, Hua-Ming

2013-10-01

In order to eliminate the deviation between the measured LIBS spectral line and the standard LIBS spectral line, and improve the accuracy of elements measurement, a research of physical deviation factors in laser induced breakdown spectroscopy technology was proposed. Under the same experimental conditions, the relationship of ablated hole effect and spectral wavelength was tested, the Stark broadening data of Mg plasma laser induced breakdown spectroscopy with sampling time-delay from 1.00 to 3.00 micros was also studied, thus the physical deviation influences such as ablated hole effect and Stark broadening could be obtained while collecting the spectrum. The results and the method of the research and analysis can also be applied to other laser induced breakdown spectroscopy experiment system, which is of great significance to improve the accuracy of LIBS elements measuring and is also important to the research on the optimum sampling time-delay of LIBS.

Prediction of breakdown voltages in novel gases for high voltage insulation

International Nuclear Information System (INIS)

Koch, M.

2015-01-01

This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the use of sulphur hexafluoride (SF_6) and similar gases as important insulation media for high voltage equipment. Due to its superior insulation properties, SF_6 is widely used in gas-insulated switchgear. However, the gas also has a very high global warming potential and the content of SF_6 in the atmosphere is constantly increasing. The search for new insulation gases using classical breakdown experiments is discussed. A model for SF_6 based on the stepped leader model is described. This calculates the breakdown voltages in arbitrary electrode configurations and under standard voltage waveforms. Thus, the thesis provides a method for the prediction of breakdown voltages of arbitrary field configurations under standard voltage waveforms for gases with electron-attaching properties. With this, further gases can be characterized for usage as high voltage insulation media

Influence of Initial Vorticity Distribution on Axisymmetric Vortex Breakdown and Reconnection

Science.gov (United States)

Young, Larry A.

2007-01-01

An analytical treatment has been developed to study some of the axisymmetric vortex breakdown and reconnection fluid dynamic processes underlying body-vortex interactions that are frequently manifested in rotorcraft and propeller-driven fixed-wing aircraft wakes. In particular, the presence of negative vorticity in the inner core of a vortex filament (one example of which is examined in this paper) subsequent to "cutting" by a solid body has a profound influence on the vortex reconnection, leading to analog flow behavior similar to vortex breakdown phenomena described in the literature. Initial vorticity distributions (three specific examples which are examined) without an inner core of negative vorticity do not exhibit vortex breakdown and instead manifest diffusion-like properties while undergoing vortex reconnection. Though this work focuses on laminar vortical flow, this work is anticipated to provide valuable insight into rotary-wing aerodynamics as well as other types of vortical flow phenomena.

Source-Drain Punch-Through Analysis of High Voltage Off-State AlGaN/GaN HEMT Breakdown

Science.gov (United States)

Jiang, H.; Li, X.; Wang, J.; Zhu, L.; Wang, H.; Liu, J.; Wang, M.; Yu, M.; Wu, W.; Zhou, Y.; Dai, G.

2017-06-01

AlGaN/GaN high-electron mobility transistor’s (HEMT’s) off-state breakdown is investigated using conventional three-terminal off-state breakdown I-V measurement. Competition between gate leakage and source-injection buffer leakage (SIBL) is discussed in detail. It is found that the breakdown is dominated by source-injection which is sensitive to gate voltage and gate length at large gate-to-drain spacing (Lgd > 7μm), where a threshold drain voltage of the occurrence of the SIBL current in GaN buffer exists, and after this threshold voltage the SIBL current continually increased till the buffer breakdown. Our analysis showed that due to the punch-through effect in the buffer, a potential barrier between 2DEG and GaN buffer at the source side mainly controlled by the drain voltage determines the buffer leakage current and the occurrence of the following buffer breakdown, which could explain the experimentally observed breakdown phenomenon.

Break-down stage in a 20 kV coaxial gun

International Nuclear Information System (INIS)

Feugeas, J.; Massa, M.; VonPamel, O.

1984-01-01

The electrical break-down of hydrogen in a coaxial electrode system (similar to Mather-type Plasma Focus) was studied for a wide range of pressures. A squirrel's cage outer electrode (cathode) of 50 mm of diameter was used to allow lateral views of the discharge, with an inner electrode (anode) of 17 mm of diameter and a pyrex sleeve of 25 mm length as insulator located at the breech of the gun. A low inductance plane plate transmission line was discharged (20 kV) through a spark gap switch over the system, with a typical peak current of 22 kA, reached after 80 ns from onset of the discharge. The fine structure of the luminous current sheath was studied by frontal and lateral open shutter photographs and by monitoring the current distribution along and across the electrodes gap. The authors tests determine the relative importance of the resistivity related to particle collision effects (αiota) and of the inductive resistivity (α L-center dot) during the break-down stage (iota=length of break-down path, L=inductance)

Influence of Low Speed Rolling Movement on High Electrical Breakdown for Water Dielectric with Microsecond Charging

International Nuclear Information System (INIS)

Zhang Zicheng; Zhang Jiande; Yang Jianhua

2006-01-01

By means of a coaxial apparatus, high electrical breakdown experiments are carried out in the rest state and the low speed rolling state with microsecond charging and the experimental results are analyzed. The conclusions are: (1) the breakdown stress of water dielectric in the rolling state is in good agreement with that in Martin formula, and so is that in the rest state; (2) the breakdown stress of water dielectric in the rolling state is about 5% higher than that in the rest state; (3) the results simulated with ANSYS demonstrate that the breakdown stress of water dielectric decreases when the bubbles appear near the surface of electrodes; (4) the primary mechanism to increase the breakdown stress of water dielectric in the rolling state is that the bubbles are driven away and the number of bubbles near the surface of electrodes is decreased by rolling movement

Protections Against Grid Breakdowns in the ITER Neutral Beam Injector Power Supplies

International Nuclear Information System (INIS)

Bigi, M.; Toigo, V.; Zanotto, L.

2006-01-01

The ITER Neutral Beam Injector (NBI) is designed to deliver 16.5 MW of additional heating power to the plasma, accelerating negative ions up to -1 MV with a current up to 40 A. Two main power supplies are foreseen to feed the system: the Acceleration Grid Power Supply (AGPS), which provides power to the acceleration grids, and the Ion Source Power Supply (ISPS), devoted to supplying the ion source components. For the accelerator, two different concepts are under investigation: the MAMuG (Multiple Aperture, Multiple Gap) and the SINGAP (SINgle Aperture). During operation of the NBI, the breakdown of the acceleration grids will occur regularly; as a consequence the AGPS is expected to experience frequent load short-circuits during a pulse. For each grid breakdown, energy and current peaks are delivered from the power supply systems that could damage the grids, if not limited. In previous NBI, rated for a lower accelerating voltage, the protection system in case of grid breakdowns was based on dc circuit breakers able to quickly disconnect the power supply from the grids. In the ITER case, a similar solution is not feasible, as the voltage level is too high for present dc breaker technology. Therefore, the protection strategy has to rely on fast switch-off of the power supplies, on the optimisation of the filter elements and core snubbers placed downstream the AGPS and on the introduction of additional passive elements. However, achieving a satisfactory protection against grid breakdowns is a challenging task, as the optimisation of each single provision can result in drawbacks for other aspects of the design; for instance, the optimisation of the filter elements, obtained by reducing the filter capacitance, produces an increase of the output voltage ripple. Therefore, the design of the protections must be carried out considering all the relevant aspects of the specifications, also those that are not strictly related to the limitations of the current peaks and energy

Individual breakdown of pension rights

CERN Multimedia

2016-01-01

You should have recently received, via email, your “Individual breakdown of pension rights”.   Please note that: the calculation was based on data as at 1st July 2016, as at 1st September 2016, CERN will introduce a new career structure; the salary position will now be expressed as a percentage of a midpoint of a grade.   We would like to draw your attention to the fact that your pension rights will remain unchanged. Benefits Service CERN Pension Fund

Dielectric breakdown in liquid helium

International Nuclear Information System (INIS)

Miller, F.L. Jr.

1975-01-01

The experimental apparatus consists of a 130 kV dc 80 kV ac intermediate voltage unit and a 600 kV dc 700 kV high voltage unit under construction. The experimental devices consist of an insulated container, or dewar, in which two electrodes are placed, one above the other. A voltage is built up in one electrode until an arc occurs to the other electrode. A typical set of breakdown data is shown. A mathematical analysis is briefly described. (MOW)

Magnetic breakdown in an array of overlapping Fermi surfaces

International Nuclear Information System (INIS)

Kadigrobov, A.M.; Radić, D.; Bjeliš, A.

2015-01-01

We develop a theoretical framework for a magnetic breakdown in an array of circular two-dimensional bands with a finite overlap of neighboring Fermi surfaces due to the presence of a presumably weak periodic potential, and apply the obtained results to the electron bands in carbon honeycomb structures of doped graphene and intercalated graphite compounds. In contrast to the standard treatment, inaugurated more than fifty years ago by Slutskin and Kadigrobov, with electron semiclassical trajectories encircling significantly overlapping Fermi surfaces, we examine a configuration in which bands are related in a way that the Fermi surfaces only slightly overlap, forming internal band pockets with areas of the size comparable to the area of the quantum magnetic flux for a given external magnetic field. Such band configuration has to be treated quantum mechanically. The calculation leads to the results for magnetic breakdown coefficients comprising an additional large factor with respect to the standard results, proportional to the ratio of the Fermi energy and the cyclotron energy. Also, these coefficients show oscillating dependence on energy, as well as on the wave number of periodic potential. Both mentioned elements enable the adjustment of the preferred wave vector of possible magnetic breakdown induced density wave instability at the highest possible critical temperature

The influence of Ac parameters in the process of micro-arc oxidation film electric breakdown

Directory of Open Access Journals (Sweden)

Ma Jin

2016-01-01

Full Text Available This paper studies the electric breakdown discharge process of micro-arc oxidation film on the surface of aluminum alloy. Based on the analysis of the AC parameters variation in the micro-arc oxidation process, the following conclusions can be drawn: The growth of oxide film can be divided into three stages, and Oxide film breakdown discharge occurs twice in the micro-arc oxidation process. The first stage is the formation and disruptive discharge of amorphous oxide film, producing the ceramic oxide granules, which belong to solid dielectric breakdown. In this stage the membrane voltage of the oxide film plays a key role; the second stage is the formation of ceramic oxide film, the ceramic oxide granules turns into porous structure oxide film in this stage; the third stage is the growth of ceramic oxide film, the gas film that forms in the oxide film’s porous structure is electric broken-down, which is the second breakdown discharge process, the current density on the oxide film surface could affect the breakdown process significantly.

Nanosecond air breakdown parameters for electron and microwave beam propagation

International Nuclear Information System (INIS)

Ali, A.W.

1988-01-01

Air breakdown by avalanche ionization plays an important role in the electron beam and microwave propagations. For high electric fields and short pulse applications one needs avalanche ionization parameters for modeling and scaling of experimental devices. However, the breakdown parameters, i.e., the ionization frequency vs E/p (volt. cm -1 . Torr -1 ) in air is uncertain for very high values of E/P. A review is given of the experimental data for the electron drift velocity, the Townsend ionization coefficient in N 2 and O 2 and the ionization frequency and the collision frequency for momentum transfer in air are developed. (author)

Improvement of powertrain efficiency through energy breakdown analysis

International Nuclear Information System (INIS)

Damiani, Lorenzo; Repetto, Matteo; Prato, Alessandro Pini

2014-01-01

Highlights: • Energy breakdown analysis for the vehicular powertrain. • Model for road vehicles simulation in different missions. • Implemented powertrain management strategies: intelligent gearbox, Stop and Start, free wheel. • Innovative hybrid powertrain turned to engine thermodynamic cycles minimization. • Evaluation of fuel savings associated to each management strategy. - Abstract: A vehicular powertrain can be thought as an energy conversion chain, each component being characterized by its efficiency. Significant global efficiency improvements can be achieved once is identified the system energy breakdown, individuating the losses connected to each powertrain component; it is then possible to carry out the most appropriate interventions. This paper presents a simulation study of a diesel-fuelled commercial vehicle powertrain based on the above summarized point of view. The work aims at individuating the energy flows involved in the system during different missions, proposing an intelligent combination of technical solutions which minimize fuel consumption. Through a validated Matlab–Simulink model, able to indicate the powertrain energy breakdown, simulations are carried out to evaluate the fuel saving associated to a series of powertrain management logics which lead to the minimization of engine losses, the recovery of reverse power in deceleration and braking, the elimination of useless engine cycles. Tests were performed for different real missions (urban, extra-urban and highway). The results obtained point out a –23% fuel consumption (average value for urban, extra-urban and highway missions) compared to the traditional powertrain. Clearly, such result affects positively the CO 2 emission

The effect of polymer type on electric breakdown strength on a nanosecond time scale

Institute of Scientific and Technical Information of China (English)

Zhao Liang; Su Jian-Cang; Pan Ya-Feng; Zhang Xi-Bo

2012-01-01

Based on the concepts of fast polarization,effective electric field and electron impact ionization criterion,the effect of polymer type on electric breakdown strength (EBD) on a nanosecond time scale is investigated,and a formula that qualitatively characterizes the relation between the electric breakdown strength and the polymer type is derived.According to this formula,it is found that the electric breakdown strength decreases with an increase in the effective relative dielectric constants of the polymers.By calculating the effective relative dielectric constants for different types of polymers,the theoretical relation for the electric breakdown strengths of common polymers is predicted.To verify the prediction,the polymers of PE (polyethylene),PTFE (polytetrafluoroethelene),PMMA (organic glass) and Nylon are tested with a nanosecond-pulse generator.The experimental result shows EBD (PTFE) ＞ EBD (PMMA) ＞ EBD (Nylon) ＞ EBD (PE).This result is consistent with the theoretical prediction.

Statistical Studies of the Electric Breakdown in Nitrogen in the Duration Range of 3 ms-60 min