The aim of this work is to attempt the application of A357 Al-Si-Mg cast alloy in the thixoextrusion process,evaluating the different forming parameters effect.Thixoextrusion offers several advantages compared with tr...The aim of this work is to attempt the application of A357 Al-Si-Mg cast alloy in the thixoextrusion process,evaluating the different forming parameters effect.Thixoextrusion offers several advantages compared with traditional hot-extrusion such as lower pressure,minor friction forces,higher material fluidity and longer tool life.This type of semi-solid process requires high solid fraction(0.7<fs<1) materials because of its low solidification rate.Aluminium alloy A357 is a commercial cast alloy characterized by high strength,ductility and corrosion resistance.It is commonly used for cast production of automotive components and it is also suitable for semi-solid process,due to its wide range of solidification.A357 aluminium alloy was used as a feedstock for thixoextrusion in order to investigate thixoformability at high solid fraction.A357 alloy with high solid fraction(>0.85) is less sensitive to temperature drops and allows more stable material flow at higher speeds.To know the forming parameters that improve the mechanical properties of thixoextruded parts,some extrusion tests were carried out.The results were used as the main criteria for assessing the thixoforming viability of the A357 alloy.展开更多
AIM: To assess the aetiological role of Helicobacter pylori (H. pylori) infection in adult patients with ironrefractory or iron-dependent anaemia of previously unknown origin. METHODS: Consecutive patients with chroni...AIM: To assess the aetiological role of Helicobacter pylori (H. pylori) infection in adult patients with ironrefractory or iron-dependent anaemia of previously unknown origin. METHODS: Consecutive patients with chronic irondeficient anaemia (IDA) with H. pylori infection and a negative standard work-up were prospectively evaluated. All of them had either iron refractoriness or iron dependency. Response to H. pylori eradication was assessed at 6 and 12 mo from follow-up. H. pylori infection was considered to be the cause of the anaemia when a complete anaemia resolution without iron supplements was observed after eradication. RESULTS: H. pylori was eradicated in 88 of the 89 patients. In the non-eradicated patient the four eradicating regimens failed. There were violations of protocol in 4 patients, for whom it was not possible to ascertain the cause of the anaemia. Thus, 84 H. pylori eradicated patients (10 men; 74 women) were available to assess the effect of eradication on IDA. H. pylori infection was considered to be the aetiology of IDA in 32 patients (38.1%; 95%CI: 28.4%-48.8%). This was more frequent in men/postmenopausal women than in premenopausal women (75% vs 23.3%; P < 0.0001) with an OR of 9.8 (95%CI: 3.3-29.6). In these patients, anaemia resolution occurred in the first follow-up visit at 6 mo, and no anaemia or iron deficiency relapse was observed after a mean follow-up of 21 ± 2 mo. CONCLUSION: Gastric H. pylori infection is a frequent cause of iron-refractory or iron-dependent anaemia of previously unknown origin in adult patients.展开更多
Anemia is a frequent finding in most diseases which cause malabsorption. The most frequent etiology is the combination of iron and vitamin B12 deficiency. Celiac disease is frequently diagnosed in patients referred fo...Anemia is a frequent finding in most diseases which cause malabsorption. The most frequent etiology is the combination of iron and vitamin B12 deficiency. Celiac disease is frequently diagnosed in patients referred for evaluation of iron deficiency anemia (IDA), being reported in 1.8%-14.6% of patients. Therefore, duodenal biopsies should be taken during endoscopy if no obvious cause of iron defi ciency (ID) can be found. Cobalamin defi ciency occurs frequently among elderly patients, but it is often unrecognized because the clinical manifestations are subtle; it is caused primarily by food-cobalamin malabsorption and pernicious anemia. The classic treatment of cobalamin deficiency has been parenteral administration of the vitamin. Recent data suggest that alternative routes of cobalamin administration (oral and nasal) may be useful in some cases. Anemia is a frequent complication of gastrectomy, and has been often described after bariatric surgery. It has been shown that banding procedures which maintain digestive continuity with the antrum and duodenum are associated with low rates of ID. Helicobacter pylori (H pylori) infection may be considered as a risk factor for IDA, mainly in groups with high demands for iron, such as some children and adolescents. Further controlled trials are needed before making solid recommendations about H pylori eradication in these cases.展开更多
Background:Universal vaccination for hepatitis B virus(HBV)and migratory movements have changed the demographic characteristics of this disease in Spain and in Europe.Therefore,we evaluated the characteristics of the ...Background:Universal vaccination for hepatitis B virus(HBV)and migratory movements have changed the demographic characteristics of this disease in Spain and in Europe.Therefore,we evaluated the characteristics of the disease and the possible differences according to origin(immigrants vs non-immigrants)and access to treatment.Methods:This is a multicenter cross-sectional study(June 2014 to May 2015)in which outpatients with a positive HBsAg were seen and followed in four Hepatology units.Demographic and clinical data and indication and access to treatment were collected in two different regions of Catalonia(Spain)where there are no barriers to treatment due to a comprehensive coverage under the National Health System.Results:A total of 951 patients were evaluated(48.1%men).Of these,46.6%were immigrants(58.7%of them were born in Africa)and were significantly younger compared to non-immigrants.The proportions of patients with alcohol consumption,being overweight,and other indicators of metabolic co-morbidities were significantly higher in non-immigrants.Among the 937 patients receiving HBeAg examination,91.7%were HBeAg-negative.Chronic HBeAg-positive infection was significantly higher in immigrants(3.9%vs 0.6%,P=0.001)and chronic HBeAg-negative hepatitis was higher non-immigrants(31.7%vs 21.4%,P<0.001).Not only was the proportion of patients who met treatment criteria significantly higher among nonimmigrants(38.4%vs 29.2%,P=0.003),but also the proportion of those with indication of effectively receiving therapy at the time of data collection(83.2%vs 57.8%,P<0.001).Conclusions:The immigrant population with HBV is younger and has a lower prevalence of metabolic co-morbidities and a higher frequency of chronic HBeAg infection.Despite having access to care and an indication for treatment,some do not get adequately treated due to several factors including local adaptation that precludes access to treatment.展开更多
We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of an elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in ou...We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of an elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. We observe differences in the dynamic behaviour if hydrodynamic interactions are considered as compared with the case without them. In conclusion, hydrodynamic interactions influence substantially the dynamics of a ratchet dimer Brownian motor;consequently they have to be considered in any theory where the molecular motors are in a liquid medium.展开更多
Experimental, theoretical and computational studies revealed that the characteristic time scales involved in counterion dynamics in polyelectrolytes systems might span several orders of magnitude ranging from subnanos...Experimental, theoretical and computational studies revealed that the characteristic time scales involved in counterion dynamics in polyelectrolytes systems might span several orders of magnitude ranging from subnanosecond times to time scales corresponding to acoustic-like phonon mode frequencies, with an structural organization of counterions in charge density waves (CDWs). These facts raise the possibility of observing Magnetic Resonance (MR) signals due to the movement of counterions in polyelectrolytes. In case that this signal is detected in macroions or other biological systems, like micelles, vesicles, organeles, etc. with rotational symmetry, this method opens a new tool to measure with precission the counterions velocity.展开更多
We consider an incompressible fluid in a rectangular nanochannel. We solve numerically the three dimensional Fourier heat equation to get the steady solution for the temperature. Then we set and solve the Langevin equ...We consider an incompressible fluid in a rectangular nanochannel. We solve numerically the three dimensional Fourier heat equation to get the steady solution for the temperature. Then we set and solve the Langevin equation for the temperature. We have developed equations in order to determine relaxation time of the temperature fluctuations, τT = 4.62 × 10-10s. We have performed a spectral analysis of the thermal fluctuations, with the result that temporal correlations are in the one-digit ps range, and the thermal noise excites the thermal modes in the two-digit GHz range. Also we observe long-range spatial correlation up to more than half the size of the cell, 600 nm;the wave number, q, is in the 106 m-1 range. We have also determined two thermal relaxation lengths in the z direction: l1 = 1.18 nm and l2 = 9.86 nm.展开更多
In this paper we discuss approximation of partially smooth functions by smooth functions. This problem arises naturally in the study of laminated currents.
Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability dis...Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability distribution of some finite-size order parameter, and the evolution of this distribution as a control parameter varies. We demonstrate this claim for the coil-globule transition of a linear polymer and its mapping onto a two-state model. In a biological context, polymer models delineate the physical constraints experienced by the genome at different levels of organization,from DNA to chromatin to chromosome. We apply our finite-size approach to the formation of plectonemes in a DNA segment submitted to an applied torque and the ensuing helix-coil transition that can be numerically observed, with a coexistence of the helix and coil states in a range of parameters. Polymer models are also essential to analyze recent in vivo experiments providing the frequency of pairwise contacts between genomic loci. The probability distribution of these contacts yields quantitative information on the conformational fluctuations of chromosome regions. The changes observed in the shape of the distribution when the cell type or the physiological conditions vary may reveal an epigenetic modulation of the conformational constraints experienced by the chromosomes.展开更多
Peroxynitrite is a highly reactive nitrogen species and a potent inducer of apoptosis and necrosis in somatic cells. Peroxynitrite-induced nitrosative stress has emerged as a major cause of impaired sperm function; ho...Peroxynitrite is a highly reactive nitrogen species and a potent inducer of apoptosis and necrosis in somatic cells. Peroxynitrite-induced nitrosative stress has emerged as a major cause of impaired sperm function; however, its ability to trigger cell death has not been described in human spermatozoa. The objective here was to characterize biochemical and morphological features of cell death induced by peroxynitrite-mediated nitrosative stress in human spermatozoa. For this, spermatozoa were incubated with and without （untreated control） 3-morpholinosydnonimine （SIN-l）, in order to generate peroxynitrite. Sperm viability, mitochondrial permeability transition （MPT）, externalization of phosphatidylserine, DNA oxidation and fragmentation, caspase activation, tyrosine nitration, and sperm ultrastructure were analyzed. The results showed that at 24 h of incubation with SIN-l, the sperm viability was significantly reduced compared to untreated control （P〈 0.001）. Furthermore, the MPT was induced （P〈 0.01） and increment in DNA oxidation （P 〈 0.01）, DNA fragmentation （P 〈 0.01）, tyrosine nitration （P 〈 0.0001） and ultrastructural damage were observed when compared to untreated control. Caspase activation was not evidenced, and although phosphatidylserine externalization increased compared to untreated control （P 〈 0.001）, this process was observed in 〈10% of the cells and the gradual loss of viability was not characterized by an important increase in this parameter. In conclusion, peroxynitrite-mediated nitrosative stress induces the regulated variant of cell death known as MPT-driven necrosis in human spermatozoa. This study provides a new insight into the pathophysiology of nitrosative stress in human spermatozoa and opens up a new focus for developing specific therapeutic strategies to better preserve sperm viability or to avoid cell death.展开更多
In this paper we show that the Kobayashi-Royden metric and the Sibony metric are different on ring domains,i.e.,the difference of two concentric balls,in higher dimension.
基金the University of Liège for the experimental supportthe Walloon Region (First Europe project)the COST 541 for their financial support
文摘The aim of this work is to attempt the application of A357 Al-Si-Mg cast alloy in the thixoextrusion process,evaluating the different forming parameters effect.Thixoextrusion offers several advantages compared with traditional hot-extrusion such as lower pressure,minor friction forces,higher material fluidity and longer tool life.This type of semi-solid process requires high solid fraction(0.7<fs<1) materials because of its low solidification rate.Aluminium alloy A357 is a commercial cast alloy characterized by high strength,ductility and corrosion resistance.It is commonly used for cast production of automotive components and it is also suitable for semi-solid process,due to its wide range of solidification.A357 aluminium alloy was used as a feedstock for thixoextrusion in order to investigate thixoformability at high solid fraction.A357 alloy with high solid fraction(>0.85) is less sensitive to temperature drops and allows more stable material flow at higher speeds.To know the forming parameters that improve the mechanical properties of thixoextruded parts,some extrusion tests were carried out.The results were used as the main criteria for assessing the thixoforming viability of the A357 alloy.
基金Supported by Grant from the Instituto de Salud Carlos Ⅲ,Spain, PI07/0748A Grant from the "Fundación Mutua Madrilea", Spain
文摘AIM: To assess the aetiological role of Helicobacter pylori (H. pylori) infection in adult patients with ironrefractory or iron-dependent anaemia of previously unknown origin. METHODS: Consecutive patients with chronic irondeficient anaemia (IDA) with H. pylori infection and a negative standard work-up were prospectively evaluated. All of them had either iron refractoriness or iron dependency. Response to H. pylori eradication was assessed at 6 and 12 mo from follow-up. H. pylori infection was considered to be the cause of the anaemia when a complete anaemia resolution without iron supplements was observed after eradication. RESULTS: H. pylori was eradicated in 88 of the 89 patients. In the non-eradicated patient the four eradicating regimens failed. There were violations of protocol in 4 patients, for whom it was not possible to ascertain the cause of the anaemia. Thus, 84 H. pylori eradicated patients (10 men; 74 women) were available to assess the effect of eradication on IDA. H. pylori infection was considered to be the aetiology of IDA in 32 patients (38.1%; 95%CI: 28.4%-48.8%). This was more frequent in men/postmenopausal women than in premenopausal women (75% vs 23.3%; P < 0.0001) with an OR of 9.8 (95%CI: 3.3-29.6). In these patients, anaemia resolution occurred in the first follow-up visit at 6 mo, and no anaemia or iron deficiency relapse was observed after a mean follow-up of 21 ± 2 mo. CONCLUSION: Gastric H. pylori infection is a frequent cause of iron-refractory or iron-dependent anaemia of previously unknown origin in adult patients.
文摘Anemia is a frequent finding in most diseases which cause malabsorption. The most frequent etiology is the combination of iron and vitamin B12 deficiency. Celiac disease is frequently diagnosed in patients referred for evaluation of iron deficiency anemia (IDA), being reported in 1.8%-14.6% of patients. Therefore, duodenal biopsies should be taken during endoscopy if no obvious cause of iron defi ciency (ID) can be found. Cobalamin defi ciency occurs frequently among elderly patients, but it is often unrecognized because the clinical manifestations are subtle; it is caused primarily by food-cobalamin malabsorption and pernicious anemia. The classic treatment of cobalamin deficiency has been parenteral administration of the vitamin. Recent data suggest that alternative routes of cobalamin administration (oral and nasal) may be useful in some cases. Anemia is a frequent complication of gastrectomy, and has been often described after bariatric surgery. It has been shown that banding procedures which maintain digestive continuity with the antrum and duodenum are associated with low rates of ID. Helicobacter pylori (H pylori) infection may be considered as a risk factor for IDA, mainly in groups with high demands for iron, such as some children and adolescents. Further controlled trials are needed before making solid recommendations about H pylori eradication in these cases.
文摘Background:Universal vaccination for hepatitis B virus(HBV)and migratory movements have changed the demographic characteristics of this disease in Spain and in Europe.Therefore,we evaluated the characteristics of the disease and the possible differences according to origin(immigrants vs non-immigrants)and access to treatment.Methods:This is a multicenter cross-sectional study(June 2014 to May 2015)in which outpatients with a positive HBsAg were seen and followed in four Hepatology units.Demographic and clinical data and indication and access to treatment were collected in two different regions of Catalonia(Spain)where there are no barriers to treatment due to a comprehensive coverage under the National Health System.Results:A total of 951 patients were evaluated(48.1%men).Of these,46.6%were immigrants(58.7%of them were born in Africa)and were significantly younger compared to non-immigrants.The proportions of patients with alcohol consumption,being overweight,and other indicators of metabolic co-morbidities were significantly higher in non-immigrants.Among the 937 patients receiving HBeAg examination,91.7%were HBeAg-negative.Chronic HBeAg-positive infection was significantly higher in immigrants(3.9%vs 0.6%,P=0.001)and chronic HBeAg-negative hepatitis was higher non-immigrants(31.7%vs 21.4%,P<0.001).Not only was the proportion of patients who met treatment criteria significantly higher among nonimmigrants(38.4%vs 29.2%,P=0.003),but also the proportion of those with indication of effectively receiving therapy at the time of data collection(83.2%vs 57.8%,P<0.001).Conclusions:The immigrant population with HBV is younger and has a lower prevalence of metabolic co-morbidities and a higher frequency of chronic HBeAg infection.Despite having access to care and an indication for treatment,some do not get adequately treated due to several factors including local adaptation that precludes access to treatment.
文摘We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of an elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. We observe differences in the dynamic behaviour if hydrodynamic interactions are considered as compared with the case without them. In conclusion, hydrodynamic interactions influence substantially the dynamics of a ratchet dimer Brownian motor;consequently they have to be considered in any theory where the molecular motors are in a liquid medium.
文摘Experimental, theoretical and computational studies revealed that the characteristic time scales involved in counterion dynamics in polyelectrolytes systems might span several orders of magnitude ranging from subnanosecond times to time scales corresponding to acoustic-like phonon mode frequencies, with an structural organization of counterions in charge density waves (CDWs). These facts raise the possibility of observing Magnetic Resonance (MR) signals due to the movement of counterions in polyelectrolytes. In case that this signal is detected in macroions or other biological systems, like micelles, vesicles, organeles, etc. with rotational symmetry, this method opens a new tool to measure with precission the counterions velocity.
文摘We consider an incompressible fluid in a rectangular nanochannel. We solve numerically the three dimensional Fourier heat equation to get the steady solution for the temperature. Then we set and solve the Langevin equation for the temperature. We have developed equations in order to determine relaxation time of the temperature fluctuations, τT = 4.62 × 10-10s. We have performed a spectral analysis of the thermal fluctuations, with the result that temporal correlations are in the one-digit ps range, and the thermal noise excites the thermal modes in the two-digit GHz range. Also we observe long-range spatial correlation up to more than half the size of the cell, 600 nm;the wave number, q, is in the 106 m-1 range. We have also determined two thermal relaxation lengths in the z direction: l1 = 1.18 nm and l2 = 9.86 nm.
基金This work is supported by the Natonal Science Foundation(NSF)(Grant No.DMS-0400614)the Schweizerische National fonds(Grant No.200021-116165/1)
文摘In this paper we discuss approximation of partially smooth functions by smooth functions. This problem arises naturally in the study of laminated currents.
基金the program "Small Systems Nonequilibrium Fluctuations,Dynamics and Stochastics,and Anomalous Behavior" of the Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences(KITPC),held in Bejing in July 2013funded by the French Institut de la Recherche M'edicale,under Grant MICROMEGAS PC201104+1 种基金the French Institut National du Cancer,under Grant INCa-5960the French Agence Nationale de la Recherche under Grant No.ANR-13-BSV5-0010-03.UPMC belongs to Sorbonne Universit'es
文摘Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability distribution of some finite-size order parameter, and the evolution of this distribution as a control parameter varies. We demonstrate this claim for the coil-globule transition of a linear polymer and its mapping onto a two-state model. In a biological context, polymer models delineate the physical constraints experienced by the genome at different levels of organization,from DNA to chromatin to chromosome. We apply our finite-size approach to the formation of plectonemes in a DNA segment submitted to an applied torque and the ensuing helix-coil transition that can be numerically observed, with a coexistence of the helix and coil states in a range of parameters. Polymer models are also essential to analyze recent in vivo experiments providing the frequency of pairwise contacts between genomic loci. The probability distribution of these contacts yields quantitative information on the conformational fluctuations of chromosome regions. The changes observed in the shape of the distribution when the cell type or the physiological conditions vary may reveal an epigenetic modulation of the conformational constraints experienced by the chromosomes.
文摘Peroxynitrite is a highly reactive nitrogen species and a potent inducer of apoptosis and necrosis in somatic cells. Peroxynitrite-induced nitrosative stress has emerged as a major cause of impaired sperm function; however, its ability to trigger cell death has not been described in human spermatozoa. The objective here was to characterize biochemical and morphological features of cell death induced by peroxynitrite-mediated nitrosative stress in human spermatozoa. For this, spermatozoa were incubated with and without （untreated control） 3-morpholinosydnonimine （SIN-l）, in order to generate peroxynitrite. Sperm viability, mitochondrial permeability transition （MPT）, externalization of phosphatidylserine, DNA oxidation and fragmentation, caspase activation, tyrosine nitration, and sperm ultrastructure were analyzed. The results showed that at 24 h of incubation with SIN-l, the sperm viability was significantly reduced compared to untreated control （P〈 0.001）. Furthermore, the MPT was induced （P〈 0.01） and increment in DNA oxidation （P 〈 0.01）, DNA fragmentation （P 〈 0.01）, tyrosine nitration （P 〈 0.0001） and ultrastructural damage were observed when compared to untreated control. Caspase activation was not evidenced, and although phosphatidylserine externalization increased compared to untreated control （P 〈 0.001）, this process was observed in 〈10% of the cells and the gradual loss of viability was not characterized by an important increase in this parameter. In conclusion, peroxynitrite-mediated nitrosative stress induces the regulated variant of cell death known as MPT-driven necrosis in human spermatozoa. This study provides a new insight into the pathophysiology of nitrosative stress in human spermatozoa and opens up a new focus for developing specific therapeutic strategies to better preserve sperm viability or to avoid cell death.
基金supported by National Science Foundation (Grant No. DMS 0705027)
文摘In this paper we show that the Kobayashi-Royden metric and the Sibony metric are different on ring domains,i.e.,the difference of two concentric balls,in higher dimension.
