A rotating neoclassical tearing mode(NTM)can increase the trapped ion losses when the frequency of the NTM is close to the precessional frequency of the trapped particles.When an equilibrium electric field,produced by...A rotating neoclassical tearing mode(NTM)can increase the trapped ion losses when the frequency of the NTM is close to the precessional frequency of the trapped particles.When an equilibrium electric field,produced by the rotation of the plasma and the density gradient,is present,the average precessional frequency of the trapped ions changes and so does the mode frequency corresponding to the maximum loss rate.Our results show that when an electric field with a value of 11.2 kV/m at q=2 is included the maximum of the trapped ion losses increases from 27% to 30% based on EAST equilibrium.展开更多
Analytical method for the residues of strobilurins azoxystrobin and pyraclostrobin in blueberries was developed. Fungicide residues were determined by solid-phase microextraction (SPME) cou-pled to gas chromatography ...Analytical method for the residues of strobilurins azoxystrobin and pyraclostrobin in blueberries was developed. Fungicide residues were determined by solid-phase microextraction (SPME) cou-pled to gas chromatography with micro-electron capture detector. The effect of pH values and fiber coatings were studied. The SPME fiber coating selected was 100 μm PDMS. The method is selective with adequate precision and high accuracy and sensitivity. Recoveries ranged within the 100% - 106% range for azoxystrobin, and 96% - 106% range for pyraclostrobin;and detection and quantification limits were 2.0 and 6.0 μg/kg for azoxystrobin, and 26.0 and 86.0 μg/kg for py-raclostrobin, respectively. Statistical parameters indicated the occurrence of matrix effect;con-sequently calibration was performed on spiked samples. Degradation of azoxystrobin and pyra-clostrobin was studied in blueberry fields located in Concordia, Argentina, with fruits from Emerald and Jewel varieties. The degradation of these fungicides in both blueberry varieties studied followed a first order rate kinetics, and the half-life for azoxystrobin was 11.6 and 17.8 days for Emerald and Jewel cultivars;and for pyraclostrobin was 5.5 and 8.0 days, respectively.展开更多
Nickel-Ti O_2 hybrid catalysts are synthesized by electrodeposition and their catalytic activity with respect to the hydrogen evolution reaction is analyzed.Two types of titanium oxide particles,which are commercial p...Nickel-Ti O_2 hybrid catalysts are synthesized by electrodeposition and their catalytic activity with respect to the hydrogen evolution reaction is analyzed.Two types of titanium oxide particles,which are commercial particles of dense Ti O_2 and mesoporous TiO_2 particles synthesized by an aerosol method,are incorporated into the matrix of the nickel catalyst.Both nickel catalysts containing Ti O_2 particles presented higher catalytic activity than the conventional nickel Watts catalyst.Mesoporous TiO_2-modified nickel catalyst showed the highest catalytic activity towards HER in alkaline medium.In addition,this type of nickel catalyst increases its catalytic activity after ageing treatment,which is an indication of an increase in the electro-active area of the electrode.展开更多
The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted ...The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.展开更多
The influence of pile-up on the nanoindentation measurements in Cu 2wt.%Be samples with precipitates was carefully studied.The precipitates were formed by aging treatments for 1 h at different temperatures between 540...The influence of pile-up on the nanoindentation measurements in Cu 2wt.%Be samples with precipitates was carefully studied.The precipitates were formed by aging treatments for 1 h at different temperatures between 540 and 680 K.The load depth curves were analyzed using the classical Oliver and Pharr method,and the obtained elastic modulus and hardness were compared with values estimated by other techniques.An important level of pile-up was found in samples with precipitates and differences in the load depth curves were observed between the unaged and aged samples.A correction of the contact depth considering the pile-up proposed by Loubet was used for hardness estimation.For the determination of the elastic modulus,an approach based on the relation between the ratio of unloading work to indentation total work,with the ratio H/Er(H is the hardness;Er is the reduced modulus),was employed.A specific relation between both parameters was developed.展开更多
Results on stress analysis for single-crystal diamonds are presented. Isolated crystals were studied by Raman mapping and depth profiling techniques, using confocal microscopy. Diamonds were deposited on molybdenum an...Results on stress analysis for single-crystal diamonds are presented. Isolated crystals were studied by Raman mapping and depth profiling techniques, using confocal microscopy. Diamonds were deposited on molybdenum and tantalum by hot filament and microwave CVD methods at growth rates between 10 and 30 μm·h-1. Crystals from 10 to 40 μm size were examined. Local stress was evaluated by analyzing the position, broadening and splitting of the 1332 cm-1 Raman peak in a 3D mapping. For the (001) orientation, the most stressed zone was found at the center of the crystal base, close to the interface with the substrate: a Raman peak around 1340 cm-1 was measured, corresponding to a pressure c.a. 3 GPa, according to our dynamical calculations. This peak disappears few microns out of the center, suggesting that this highly concentrated stress sector was the nucleation zone of the crystal. A shifting and slight broadening of the 1332 cm-1 band was observed in the rest of the crystal. The causes of these effects are discussed: they proved not to be due to anisotropic stress but to refractive effects. Same results were found for different crystal sizes and growth rates.展开更多
The^(10)boron neutron-capture therapy(BNCT)is an emerging antitumoral method that shows increasing biomedical interest.BNCT is based on the selective accumulation of the^(10)boron isotope within the tumor,which is the...The^(10)boron neutron-capture therapy(BNCT)is an emerging antitumoral method that shows increasing biomedical interest.BNCT is based on the selective accumulation of the^(10)boron isotope within the tumor,which is then irradiated with low-energy thermal neutrons,generating nuclear fission that produces 7lithium,4helium,andγrays.Simple catechol-borate esters have been rather overlooked as precursors of melanin biosynthesis,and therefore,a proof-of-concept approach for using dopamine-borate(DABO)as a suitable boron-containing candidate for potential BNCT is presented here.DABO can spontaneously oxidize and autopolymerize in vitro,giving a soluble,eumelaninlike brown-black poly-DABO product.Melanotic melanoma cell cultures treated with 1 mM DABO for 24 and 48 h were viable and showed no signs of damage or cell death.The stability and possible trans-esterification of DABO is shortly discussed.Chemical calculations and quantitative structure-activity relationships(QSAR)analysis of DABO and the BNCT agent BPA indicated that they should be cell permeant and accumulate within lysosomes and melanosomes.Molecular modeling allows visualization of both the DABO precursor and the structure of a borate derivative of the proposed catechol-porphycene model for eumelanin,showing interesting features from molecular orbital calculations.The main difference between DABO and other agents,such as BPA,is that it is not a boronic acid nor a boron cluster.This simple catechol-borate ester(protected from oxidation and blackening)could be administrated to living cells and organisms,in which biosynthesis of boron-melanin in melanoma melanocytes can lead to improved BNCT.展开更多
AIM:To evaluate the relationships between the personal, sociocultural,and environmental characteristics,and the presence or absence of symptoms with the detection of Enterobius vermicularis(E.vermicularis)in a populat...AIM:To evaluate the relationships between the personal, sociocultural,and environmental characteristics,and the presence or absence of symptoms with the detection of Enterobius vermicularis(E.vermicularis)in a population sample in our region(General Mansilla,Province of Buenos Aires,Argentina),by individual and familiar analyses. METHODS:E.verrnicularis was diagnosed in 309 people from 70 family units residing in the urban area and the rural area of the city of General Mansilla.Each of them was surveyed so as to register personal,environmental and sociocultural data.Questions about the presence or absence of anal itch,abdominal pain and sleeping disorder were also asked.Significant associations were determined by square chi tests.Logistic regression models were adjusted by using a backward conditional stepwise method to determine the presence of this parasite in the individuals and in the families. RESULTS:The parasites were found in 29.12%(90/309) of the individuals,with a frequency of 14.28%(20/140) among the heads of the families and of 41.42%(70/169) among the children.The only variables showing a significant association were affiliation,where the risk category was “being the son/daughter of”,and the symptoms were abdominal pain,sleeping disorder,and anal itch.Families with a member infected with parasite were considered Positive Families(PF)and they were 40/70(57.14%),only 5%(2/40)of the PF had 100% of their members infected with the parasite.The logistic regression models applied showed that the risk categories were mainly affiliation(son/daughter) and housing(satisfactory)among others. CONCLUSION:The presence of E.vermiculariswas proved in one third of the studied population.The frequency of families with all their members infected with the parasite was very low.Most of the studied personal,sociocultural, and environmental variables did not turn out to be significantly associated with the presence of the parasite.An association with the category of“son/daughter”and housing classified as“satisfactory”was determined.The latter may be due to the fact that the people living in that category of housing have hygienic practices at home that favour the distribution of the eggs in the environment.The presence of the analysed symptoms was associated with the presence of the parasite, thus strengthening the need of periodical control of the population showing at least one of these symptoms.展开更多
The new reactor concepts are characterized by higher efficiency, better utilization of nuclear fuel and nuclear waste minimization. This approach means that it is necessary to continue a continued research and test of...The new reactor concepts are characterized by higher efficiency, better utilization of nuclear fuel and nuclear waste minimization. This approach means that it is necessary to continue a continued research and test of new materials in order to apply them in new reactors. In this study, the authors fbcused on the analysis of SiC alloys because, due to their particular properties, this alloy can be used in high temperature conditions where the pure silicon, semiconductor material par excellence, is inadequate to support them.展开更多
Under the present changing climate conditions and the observed temperature increase,it is of high importance to understand its effects on aquatic microbial life,and organisms’adaptations at the biochemical level.To a...Under the present changing climate conditions and the observed temperature increase,it is of high importance to understand its effects on aquatic microbial life,and organisms’adaptations at the biochemical level.To adjust to temperature or salinity stress and avoid cell damage,organisms alter their degree of fatty acids(FAs)saturation.Thus,temperature is expected to have strong effects on both the quantity and quality of FAs in aquatic microorganisms.Here we review some recent findings about FAs sensitivity to climate change in contrasting environments.Overall,heat waves may induce changes in the relative abundance of polyunsaturated FAs(PUFA).However,the impact of the exposure to warming waters is different in temperate and polar environments.In cold marine waters,high concentration of omega-3(ω3)FAs such as eicosapentaenoic acid(EPA)is promoted due to the activation of the desaturase enzyme.In this way,cells have enough energy to produce or activate antioxidant protection mechanisms and avoid oxidative stress due to heat waves.Contrastingly,under high irradiance and heat wave conditions in temperate environments,photosystems’protection is achieved by decreasing EPA concentration due to desaturase sensitivity.Essential FAs are transferred in aquatic food webs.Therefore,any alteration in the production of essential FAs by phytoplankton(the main source ofω3)due to climate warming can be transferred to higher trophic levels,with cascading effects for the entire aquatic ecosystem.展开更多
A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In t...A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In the south zone, important effects of reinjection were observed through Cl increases in some wells (up to 8000 mg/kg) while in wells with significant boiling, Cl has decreased. In most of the north zone wells, the variations in gas data indicated boiling and condensation of a highly gas-depleted brine, which seems to consist of reinjection fluids. It is suggested that this process maintains the production in the zone relatively stable. The main reservoir exploitation-related processes found were: 1) production of reinjection returns;for this, it was possible to distinguish a) wells that produce liquid and steam from injection, and b) wells that produce steam from injection and sometimes condensed steam from injection;2) boiling: two types of boiling were identified: a) boiling with steam gain, and b) boiling with steam loss. The results indicated that an effective reservoir recharge occurs since very moderate production declining rates were found.展开更多
A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field consistent with a given internal magnetohydrodynamic(MHD) equilibrium and coil geometry is presented. The const...A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field consistent with a given internal magnetohydrodynamic(MHD) equilibrium and coil geometry is presented. The constrained optimization technique employed allows to fix the exact position of the X-points. The external poloidal flux and field are calculated using Green's functions expressed in terms of elliptic integrals that are calculated using a fast and accurate routine.The calculation can be limited to the region between the plasma and the device wall. An example for a double null configuration is presented.展开更多
BACKGROUND The estimation of left ventricular ejection fraction(LVEF)by 2D echocardiography(2D-ECHO)is the most used tool to assess LV systolic function(LVSF).Global longitudinal strain(GLS)has recently been suggested...BACKGROUND The estimation of left ventricular ejection fraction(LVEF)by 2D echocardiography(2D-ECHO)is the most used tool to assess LV systolic function(LVSF).Global longitudinal strain(GLS)has recently been suggested as a superior method for several evaluations.This study explored the association and prevalence of LV systolic dysfunction(LVSD)by using these methods in patients with end-stage renal disease(ESRD)and severe hyperparathyroidism(SHPTH);both associated with cardiovascular events(CEs).AIM To evaluate the myocardial function in patients with ESRD and SHPTH by using the GLS and LVEF measured through conventional 2D-ECHO.METHODS In 62 patients with ESRD and SHPTH,asymptomatic,and without a history of CEs,LVSF was evaluated by 2D-ECHO,obtaining the EF,by the Simpson biplane method,and GLS by speckle tracking.RESULTS The total patients with ESRD had a preserved LVEF(>50%)but abnormal GLS(<13.55%).Additionally,multivariate analysis showed an independent association of GLS and serum parathyroid hormone(PTH),LV mass index,and hemoglobin.Also,PTH was independently associated with lateral e'wave and tricuspid regurgitation velocity.CONCLUSION In patients with SHPTH linked to ESRD,the use of GLS by 2D-ECHO is a more sensitive tool than LVEF for detecting LVSD.展开更多
We extend a recently proposed Quantum Field Theory (QFT) approach to the Lifshitz formula, originally implemented for a real scalar field, to the case of a fluctuating vacuum Electromagnetic (EM) field, coupled to two...We extend a recently proposed Quantum Field Theory (QFT) approach to the Lifshitz formula, originally implemented for a real scalar field, to the case of a fluctuating vacuum Electromagnetic (EM) field, coupled to two flat, parallel mirrors. The general result is presented in terms of the invariants of the vacuum polarization tensors due to the media on each mirror. We consider mirrors that have small widths, with the zero-width limit as a particular case. We apply the latter to models involving graphene sheets, obtaining results which are consistent with previous ones.展开更多
The ajenjo,Artemisia mendozana DC.var.mendozana(Asteraceae),grows in the Andean foothills of Mendoza and San Juan,Argentina,and is used as a medicinal plant for its antispasmodic and antifungal properties.The aim of t...The ajenjo,Artemisia mendozana DC.var.mendozana(Asteraceae),grows in the Andean foothills of Mendoza and San Juan,Argentina,and is used as a medicinal plant for its antispasmodic and antifungal properties.The aim of this work was to obtain fractions of a chloroform extract of ajenjo leaves and to evaluate the in vitro effects on proliferation,viability and clonogenicity of B16-F0 melanoma cells.Using a silica gel chromatography column,120 fractions were collected and grouped according to the chromatographic profile in 9 main fractions(F1–F9).Their major compounds identified were:terpenes(F1),terpenes and sesquiterpene lactones(F2–F3),sesquiterpenes(F4–F6)and phenols and sesquiterpenes(F7-9).B16-F0 cells were incubated for 72 h with DMSO(vehicle)or 0.1 mg/ml F1–F9.At 72 h of culture,F1 decreased both the growing index(GI)and cell viability.F2 and F3 both decreased GI and only F3 decreased clonogenic activity.F4 and F5 both decreased GI.Only F5 decreased cell viability and F4 decreased clonogenicity.Consequently,fractions F6–F8 did not affect any of the cell parameters assayed,while F9 decreased cell viability and inhibited clonogenicity.展开更多
The existence of the thorium element in the ores from the Atacama region, Chile, and its importance in the activities of the nuclear industry, have generated the interest of the Chilean Nuclear Energy Commission (CChE...The existence of the thorium element in the ores from the Atacama region, Chile, and its importance in the activities of the nuclear industry, have generated the interest of the Chilean Nuclear Energy Commission (CChEN) to study the technical feasibility of its recovery, like ThO2 through the implementation of hydrometallurgical techniques, such as leaching, solvent extraction, among others. The present work has become a report about the research carried out in the Extractive Metallurgy Area of the Department of Advanced Materials of CChEN, whose objective is to know the behavior of the thorium element when the mineral carrier is leached. The leaching tests were carried out in a glass reactor in batch mode, by mechanical agitation, varying different operational parameters, such as: type of leaching solution, concentration of acid in the solution, system temperature and granulometry of the mineral. The results indicate that there is technical feasibility for the recovery of thorium by leaching the mineral carrier with hydrochloric and/or sulfuric solution. The highest recovery of thorium for a sulfuric solution was 70.0% and for a hydrochloric solution of 83.8%, so the process presents a good efficiency in both cases. For a hydrochloric solution, the mathematical model of the thorium recovery efficiency obtained is: Y=31.14+26.25*X1+8.69*X2−0.82*X3+9.5*X12−0.83*X13−3.71*X23−1.83*X123+6.45 The concentration of HCl and temperature, as well as their interaction, significantly affect the recovery of thorium for Sierra Indiana mineral, as well as temperature and granulometry. The previous model gives a good representativeness of 99.98%. For a sulfuric solution, the mathematical model of the thorium recovery efficiency obtained is: Y=29.78+25.92*X1+0.99*X2−1.05*X3−2.05*X12−9.84*X13−5.26*X23−3.87*X123+15.18 The model indicates that the recovery of thorium for the mineral is significantly affected by the concentration of sulfuric acid, and to a lesser degree by the temperature and granulometry. The model provides a representativeness of 98.3%.展开更多
The industrial obtainment and manufacturing of food cause high levels of pollution because of the generation of waste byproducts. Over the past few years, there has been a significantly increased interest in preservin...The industrial obtainment and manufacturing of food cause high levels of pollution because of the generation of waste byproducts. Over the past few years, there has been a significantly increased interest in preserving, restoring and establishing an ecological balance during food production. Many investigators propose biotechnological solutions to the treatment of industrial wastes, especially waste from the dairy industry. The aim of this review is to present biotechnological approaches to the treatment and utilization of wastes from the dairy industry, specifically for milk whey and also discussed biotechnological methods to reduce environmental pollution and obtain chemical compounds with potential applications in the industry.展开更多
The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe alloys.Variations in the load-dept...The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe alloys.Variations in the load-depth curves at different loads would suggest a change in the behavior of the materials as the load increases.Nanohardness was estimated at different loads taking into account the pile-up in each case,which was estimated from the images of the topography obtained by atomic force microscopy(AFM).The effect of the microstructure of Cu-2Be(wt%)samples on the ISE was also studied.For each copper alloy,the Nix and Gao model was applied to the hardness-depth curves,and significant differences were found for the parameters obtained.Cu is in the constant nanohardness regime for depths below 500 nm,while microhardness exhibits the ISE effect.The behavior of the nanohardness and the plastic strain with the depth is almost inverse.CuAlBe presents the lowest values of plastic strains due to the pseudoelastic effect,while Cu presents an almost constant value around 8%,which corresponds to the highest plastic strain obtained.展开更多
We reconsider the Mott transition in the context of a two-dimensional fermion model with density-density coupling. We exhibit a Hilbert space mapping between the original model and the Double Lattice Chern-Simons theo...We reconsider the Mott transition in the context of a two-dimensional fermion model with density-density coupling. We exhibit a Hilbert space mapping between the original model and the Double Lattice Chern-Simons theory at the critical point by use of the representation theory of the q-oscillator and Weyl algebras. The transition is further characterized by the ground state modification. The explicit mapping provides a new tool to further probe and test the detailed physical properties of the fermionic lattice model considered here and to enhance our understanding of the Mott transition(s).展开更多
The water chemistry of the secondary coolant in the majority of Nuclear Power Plants is controlled by AVT (All Volatile Treatment), wherein volatile amines are used to maintain the alkaline pH required for minimizing ...The water chemistry of the secondary coolant in the majority of Nuclear Power Plants is controlled by AVT (All Volatile Treatment), wherein volatile amines are used to maintain the alkaline pH required for minimizing the corrosion of structural materials which one of them is Carbon Steel. In this treatment, ammonia, morpholine and ethanolamine are commonly used as conditioning reagents. In this context, experiments were carried out by exposing carbon steel A106 B samples in a simulated secondary coolant in order to study the nature of the oxide films. The tests were performed in a static autoclave at 260°C using two media: I) hydrazine + morpholine and II) hydrazine + ethanolamine during different exposure periods up to ≈1020 h. The oxide film characterization was mainly studied using Scanning Electron Microscopy and X-ray diffraction. A chemical descaling procedure was used to obtain the material weight loss (W) of samples, the adherent and released oxide. The XRD analyses, for all exposures studied, showed that magnetite was the corrosion product formed in the films grown in both media. The material weight loss, after descaling, could be fitted by a law of the type W = ktn, up to 1020 h of exposure tested, resulting in n = 0.42, k = 6.24 for films grown in medium I) and n = 0.39, k = 6.08 for films grown in medium II) respectively (W is in mg/dm2 and t in h). The higher corrosion product release measured in the medium with morpholine could be important in power plant operation.展开更多
基金partially supported by the Comisión Nacional de Energía Atómica,CNEA(Controlled Nuclear Fusion Program),CONICET(No.11220200101929CO)Universidad Nacional de Cuyo(No.06-C565).
文摘A rotating neoclassical tearing mode(NTM)can increase the trapped ion losses when the frequency of the NTM is close to the precessional frequency of the trapped particles.When an equilibrium electric field,produced by the rotation of the plasma and the density gradient,is present,the average precessional frequency of the trapped ions changes and so does the mode frequency corresponding to the maximum loss rate.Our results show that when an electric field with a value of 11.2 kV/m at q=2 is included the maximum of the trapped ion losses increases from 27% to 30% based on EAST equilibrium.
文摘Analytical method for the residues of strobilurins azoxystrobin and pyraclostrobin in blueberries was developed. Fungicide residues were determined by solid-phase microextraction (SPME) cou-pled to gas chromatography with micro-electron capture detector. The effect of pH values and fiber coatings were studied. The SPME fiber coating selected was 100 μm PDMS. The method is selective with adequate precision and high accuracy and sensitivity. Recoveries ranged within the 100% - 106% range for azoxystrobin, and 96% - 106% range for pyraclostrobin;and detection and quantification limits were 2.0 and 6.0 μg/kg for azoxystrobin, and 26.0 and 86.0 μg/kg for py-raclostrobin, respectively. Statistical parameters indicated the occurrence of matrix effect;con-sequently calibration was performed on spiked samples. Degradation of azoxystrobin and pyra-clostrobin was studied in blueberry fields located in Concordia, Argentina, with fruits from Emerald and Jewel varieties. The degradation of these fungicides in both blueberry varieties studied followed a first order rate kinetics, and the half-life for azoxystrobin was 11.6 and 17.8 days for Emerald and Jewel cultivars;and for pyraclostrobin was 5.5 and 8.0 days, respectively.
基金financial support from "Agencia Nacional de Promoción Científica y Tecnológica" (PICT 1818)CONICET (PIP 112 201301 00808)
文摘Nickel-Ti O_2 hybrid catalysts are synthesized by electrodeposition and their catalytic activity with respect to the hydrogen evolution reaction is analyzed.Two types of titanium oxide particles,which are commercial particles of dense Ti O_2 and mesoporous TiO_2 particles synthesized by an aerosol method,are incorporated into the matrix of the nickel catalyst.Both nickel catalysts containing Ti O_2 particles presented higher catalytic activity than the conventional nickel Watts catalyst.Mesoporous TiO_2-modified nickel catalyst showed the highest catalytic activity towards HER in alkaline medium.In addition,this type of nickel catalyst increases its catalytic activity after ageing treatment,which is an indication of an increase in the electro-active area of the electrode.
基金the Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET,Argentina)(PIP 20170100677)the Fondo para la Investigación Científica y Tecnológica(FONCYT)(PICT-2017-1318)the Universidad Nacional de Mar del Plata(UNMdP,15/G557,ING561/19)and to the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires(CIC)and the Universidad Tecnológica Nacional(UTN)for their financial support.
文摘The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.
基金supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CICPBA)SECAT (UNCPBA) Argentina
文摘The influence of pile-up on the nanoindentation measurements in Cu 2wt.%Be samples with precipitates was carefully studied.The precipitates were formed by aging treatments for 1 h at different temperatures between 540 and 680 K.The load depth curves were analyzed using the classical Oliver and Pharr method,and the obtained elastic modulus and hardness were compared with values estimated by other techniques.An important level of pile-up was found in samples with precipitates and differences in the load depth curves were observed between the unaged and aged samples.A correction of the contact depth considering the pile-up proposed by Loubet was used for hardness estimation.For the determination of the elastic modulus,an approach based on the relation between the ratio of unloading work to indentation total work,with the ratio H/Er(H is the hardness;Er is the reduced modulus),was employed.A specific relation between both parameters was developed.
文摘Results on stress analysis for single-crystal diamonds are presented. Isolated crystals were studied by Raman mapping and depth profiling techniques, using confocal microscopy. Diamonds were deposited on molybdenum and tantalum by hot filament and microwave CVD methods at growth rates between 10 and 30 μm·h-1. Crystals from 10 to 40 μm size were examined. Local stress was evaluated by analyzing the position, broadening and splitting of the 1332 cm-1 Raman peak in a 3D mapping. For the (001) orientation, the most stressed zone was found at the center of the crystal base, close to the interface with the substrate: a Raman peak around 1340 cm-1 was measured, corresponding to a pressure c.a. 3 GPa, according to our dynamical calculations. This peak disappears few microns out of the center, suggesting that this highly concentrated stress sector was the nucleation zone of the crystal. A shifting and slight broadening of the 1332 cm-1 band was observed in the rest of the crystal. The causes of these effects are discussed: they proved not to be due to anisotropic stress but to refractive effects. Same results were found for different crystal sizes and growth rates.
文摘The^(10)boron neutron-capture therapy(BNCT)is an emerging antitumoral method that shows increasing biomedical interest.BNCT is based on the selective accumulation of the^(10)boron isotope within the tumor,which is then irradiated with low-energy thermal neutrons,generating nuclear fission that produces 7lithium,4helium,andγrays.Simple catechol-borate esters have been rather overlooked as precursors of melanin biosynthesis,and therefore,a proof-of-concept approach for using dopamine-borate(DABO)as a suitable boron-containing candidate for potential BNCT is presented here.DABO can spontaneously oxidize and autopolymerize in vitro,giving a soluble,eumelaninlike brown-black poly-DABO product.Melanotic melanoma cell cultures treated with 1 mM DABO for 24 and 48 h were viable and showed no signs of damage or cell death.The stability and possible trans-esterification of DABO is shortly discussed.Chemical calculations and quantitative structure-activity relationships(QSAR)analysis of DABO and the BNCT agent BPA indicated that they should be cell permeant and accumulate within lysosomes and melanosomes.Molecular modeling allows visualization of both the DABO precursor and the structure of a borate derivative of the proposed catechol-porphycene model for eumelanin,showing interesting features from molecular orbital calculations.The main difference between DABO and other agents,such as BPA,is that it is not a boronic acid nor a boron cluster.This simple catechol-borate ester(protected from oxidation and blackening)could be administrated to living cells and organisms,in which biosynthesis of boron-melanin in melanoma melanocytes can lead to improved BNCT.
基金Supported by the Agencia Nacional de Promoci6n Científica y Técnica de la Argentina,the Alberto J.Roemmers Foundation,and the Universidad Nacional de La Plata,and it was declared of Municipal Interest by the town of Magdalena,Province of Buenos Ai
文摘AIM:To evaluate the relationships between the personal, sociocultural,and environmental characteristics,and the presence or absence of symptoms with the detection of Enterobius vermicularis(E.vermicularis)in a population sample in our region(General Mansilla,Province of Buenos Aires,Argentina),by individual and familiar analyses. METHODS:E.verrnicularis was diagnosed in 309 people from 70 family units residing in the urban area and the rural area of the city of General Mansilla.Each of them was surveyed so as to register personal,environmental and sociocultural data.Questions about the presence or absence of anal itch,abdominal pain and sleeping disorder were also asked.Significant associations were determined by square chi tests.Logistic regression models were adjusted by using a backward conditional stepwise method to determine the presence of this parasite in the individuals and in the families. RESULTS:The parasites were found in 29.12%(90/309) of the individuals,with a frequency of 14.28%(20/140) among the heads of the families and of 41.42%(70/169) among the children.The only variables showing a significant association were affiliation,where the risk category was “being the son/daughter of”,and the symptoms were abdominal pain,sleeping disorder,and anal itch.Families with a member infected with parasite were considered Positive Families(PF)and they were 40/70(57.14%),only 5%(2/40)of the PF had 100% of their members infected with the parasite.The logistic regression models applied showed that the risk categories were mainly affiliation(son/daughter) and housing(satisfactory)among others. CONCLUSION:The presence of E.vermiculariswas proved in one third of the studied population.The frequency of families with all their members infected with the parasite was very low.Most of the studied personal,sociocultural, and environmental variables did not turn out to be significantly associated with the presence of the parasite.An association with the category of“son/daughter”and housing classified as“satisfactory”was determined.The latter may be due to the fact that the people living in that category of housing have hygienic practices at home that favour the distribution of the eggs in the environment.The presence of the analysed symptoms was associated with the presence of the parasite, thus strengthening the need of periodical control of the population showing at least one of these symptoms.
文摘The new reactor concepts are characterized by higher efficiency, better utilization of nuclear fuel and nuclear waste minimization. This approach means that it is necessary to continue a continued research and test of new materials in order to apply them in new reactors. In this study, the authors fbcused on the analysis of SiC alloys because, due to their particular properties, this alloy can be used in high temperature conditions where the pure silicon, semiconductor material par excellence, is inadequate to support them.
基金The research leading to these results further received funding grants ANPCYT PICT 2011-130 Raíces of the Agencia Nacional de Promociones Científicas of Argentina to IRS and MPH,and from the European Union’s Horizon 2020 research and innovation program under grant agreement No.730984,ASSEMBLEPLUS2019359 Project awarded to FDIt is further a contribution to CoastCarb(Funding ID 872609,H2020,MSCA-RISE-2019,Research and Innovation Staff Exchange).
文摘Under the present changing climate conditions and the observed temperature increase,it is of high importance to understand its effects on aquatic microbial life,and organisms’adaptations at the biochemical level.To adjust to temperature or salinity stress and avoid cell damage,organisms alter their degree of fatty acids(FAs)saturation.Thus,temperature is expected to have strong effects on both the quantity and quality of FAs in aquatic microorganisms.Here we review some recent findings about FAs sensitivity to climate change in contrasting environments.Overall,heat waves may induce changes in the relative abundance of polyunsaturated FAs(PUFA).However,the impact of the exposure to warming waters is different in temperate and polar environments.In cold marine waters,high concentration of omega-3(ω3)FAs such as eicosapentaenoic acid(EPA)is promoted due to the activation of the desaturase enzyme.In this way,cells have enough energy to produce or activate antioxidant protection mechanisms and avoid oxidative stress due to heat waves.Contrastingly,under high irradiance and heat wave conditions in temperate environments,photosystems’protection is achieved by decreasing EPA concentration due to desaturase sensitivity.Essential FAs are transferred in aquatic food webs.Therefore,any alteration in the production of essential FAs by phytoplankton(the main source ofω3)due to climate warming can be transferred to higher trophic levels,with cascading effects for the entire aquatic ecosystem.
文摘A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In the south zone, important effects of reinjection were observed through Cl increases in some wells (up to 8000 mg/kg) while in wells with significant boiling, Cl has decreased. In most of the north zone wells, the variations in gas data indicated boiling and condensation of a highly gas-depleted brine, which seems to consist of reinjection fluids. It is suggested that this process maintains the production in the zone relatively stable. The main reservoir exploitation-related processes found were: 1) production of reinjection returns;for this, it was possible to distinguish a) wells that produce liquid and steam from injection, and b) wells that produce steam from injection and sometimes condensed steam from injection;2) boiling: two types of boiling were identified: a) boiling with steam gain, and b) boiling with steam loss. The results indicated that an effective reservoir recharge occurs since very moderate production declining rates were found.
基金supported by the Comisión Nacional de Energía Atómica, CNEA (Controlled Nuclear Fusion Program)CONICET (Grant PIP 11220200101929CO)。
文摘A simple and fast method to calculate the coil currents and the external poloidal flux and magnetic field consistent with a given internal magnetohydrodynamic(MHD) equilibrium and coil geometry is presented. The constrained optimization technique employed allows to fix the exact position of the X-points. The external poloidal flux and field are calculated using Green's functions expressed in terms of elliptic integrals that are calculated using a fast and accurate routine.The calculation can be limited to the region between the plasma and the device wall. An example for a double null configuration is presented.
基金Supported by the Secretaría de Investigación y Posgrado of the Instituto Politécnico Nacionalthe Comisión de Operación y Fomento de Actividades Académicas of the Instituto Politécnico Nacionalthe Consejo Nacional de Ciencia y Tecnología
文摘BACKGROUND The estimation of left ventricular ejection fraction(LVEF)by 2D echocardiography(2D-ECHO)is the most used tool to assess LV systolic function(LVSF).Global longitudinal strain(GLS)has recently been suggested as a superior method for several evaluations.This study explored the association and prevalence of LV systolic dysfunction(LVSD)by using these methods in patients with end-stage renal disease(ESRD)and severe hyperparathyroidism(SHPTH);both associated with cardiovascular events(CEs).AIM To evaluate the myocardial function in patients with ESRD and SHPTH by using the GLS and LVEF measured through conventional 2D-ECHO.METHODS In 62 patients with ESRD and SHPTH,asymptomatic,and without a history of CEs,LVSF was evaluated by 2D-ECHO,obtaining the EF,by the Simpson biplane method,and GLS by speckle tracking.RESULTS The total patients with ESRD had a preserved LVEF(>50%)but abnormal GLS(<13.55%).Additionally,multivariate analysis showed an independent association of GLS and serum parathyroid hormone(PTH),LV mass index,and hemoglobin.Also,PTH was independently associated with lateral e'wave and tricuspid regurgitation velocity.CONCLUSION In patients with SHPTH linked to ESRD,the use of GLS by 2D-ECHO is a more sensitive tool than LVEF for detecting LVSD.
文摘We extend a recently proposed Quantum Field Theory (QFT) approach to the Lifshitz formula, originally implemented for a real scalar field, to the case of a fluctuating vacuum Electromagnetic (EM) field, coupled to two flat, parallel mirrors. The general result is presented in terms of the invariants of the vacuum polarization tensors due to the media on each mirror. We consider mirrors that have small widths, with the zero-width limit as a particular case. We apply the latter to models involving graphene sheets, obtaining results which are consistent with previous ones.
文摘The ajenjo,Artemisia mendozana DC.var.mendozana(Asteraceae),grows in the Andean foothills of Mendoza and San Juan,Argentina,and is used as a medicinal plant for its antispasmodic and antifungal properties.The aim of this work was to obtain fractions of a chloroform extract of ajenjo leaves and to evaluate the in vitro effects on proliferation,viability and clonogenicity of B16-F0 melanoma cells.Using a silica gel chromatography column,120 fractions were collected and grouped according to the chromatographic profile in 9 main fractions(F1–F9).Their major compounds identified were:terpenes(F1),terpenes and sesquiterpene lactones(F2–F3),sesquiterpenes(F4–F6)and phenols and sesquiterpenes(F7-9).B16-F0 cells were incubated for 72 h with DMSO(vehicle)or 0.1 mg/ml F1–F9.At 72 h of culture,F1 decreased both the growing index(GI)and cell viability.F2 and F3 both decreased GI and only F3 decreased clonogenic activity.F4 and F5 both decreased GI.Only F5 decreased cell viability and F4 decreased clonogenicity.Consequently,fractions F6–F8 did not affect any of the cell parameters assayed,while F9 decreased cell viability and inhibited clonogenicity.
文摘The existence of the thorium element in the ores from the Atacama region, Chile, and its importance in the activities of the nuclear industry, have generated the interest of the Chilean Nuclear Energy Commission (CChEN) to study the technical feasibility of its recovery, like ThO2 through the implementation of hydrometallurgical techniques, such as leaching, solvent extraction, among others. The present work has become a report about the research carried out in the Extractive Metallurgy Area of the Department of Advanced Materials of CChEN, whose objective is to know the behavior of the thorium element when the mineral carrier is leached. The leaching tests were carried out in a glass reactor in batch mode, by mechanical agitation, varying different operational parameters, such as: type of leaching solution, concentration of acid in the solution, system temperature and granulometry of the mineral. The results indicate that there is technical feasibility for the recovery of thorium by leaching the mineral carrier with hydrochloric and/or sulfuric solution. The highest recovery of thorium for a sulfuric solution was 70.0% and for a hydrochloric solution of 83.8%, so the process presents a good efficiency in both cases. For a hydrochloric solution, the mathematical model of the thorium recovery efficiency obtained is: Y=31.14+26.25*X1+8.69*X2−0.82*X3+9.5*X12−0.83*X13−3.71*X23−1.83*X123+6.45 The concentration of HCl and temperature, as well as their interaction, significantly affect the recovery of thorium for Sierra Indiana mineral, as well as temperature and granulometry. The previous model gives a good representativeness of 99.98%. For a sulfuric solution, the mathematical model of the thorium recovery efficiency obtained is: Y=29.78+25.92*X1+0.99*X2−1.05*X3−2.05*X12−9.84*X13−5.26*X23−3.87*X123+15.18 The model indicates that the recovery of thorium for the mineral is significantly affected by the concentration of sulfuric acid, and to a lesser degree by the temperature and granulometry. The model provides a representativeness of 98.3%.
文摘The industrial obtainment and manufacturing of food cause high levels of pollution because of the generation of waste byproducts. Over the past few years, there has been a significantly increased interest in preserving, restoring and establishing an ecological balance during food production. Many investigators propose biotechnological solutions to the treatment of industrial wastes, especially waste from the dairy industry. The aim of this review is to present biotechnological approaches to the treatment and utilization of wastes from the dairy industry, specifically for milk whey and also discussed biotechnological methods to reduce environmental pollution and obtain chemical compounds with potential applications in the industry.
基金This work was financially supported by the Consejo Nacional de Investigaciones Cientfficas y Tecnicas(CONI-CET)the Comision de Investigaciones Cientfficas de la Provincia de Buenos Aires(CICPBA)the SECAT(UNCPBA)Argentina.
文摘The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe alloys.Variations in the load-depth curves at different loads would suggest a change in the behavior of the materials as the load increases.Nanohardness was estimated at different loads taking into account the pile-up in each case,which was estimated from the images of the topography obtained by atomic force microscopy(AFM).The effect of the microstructure of Cu-2Be(wt%)samples on the ISE was also studied.For each copper alloy,the Nix and Gao model was applied to the hardness-depth curves,and significant differences were found for the parameters obtained.Cu is in the constant nanohardness regime for depths below 500 nm,while microhardness exhibits the ISE effect.The behavior of the nanohardness and the plastic strain with the depth is almost inverse.CuAlBe presents the lowest values of plastic strains due to the pseudoelastic effect,while Cu presents an almost constant value around 8%,which corresponds to the highest plastic strain obtained.
文摘We reconsider the Mott transition in the context of a two-dimensional fermion model with density-density coupling. We exhibit a Hilbert space mapping between the original model and the Double Lattice Chern-Simons theory at the critical point by use of the representation theory of the q-oscillator and Weyl algebras. The transition is further characterized by the ground state modification. The explicit mapping provides a new tool to further probe and test the detailed physical properties of the fermionic lattice model considered here and to enhance our understanding of the Mott transition(s).
文摘The water chemistry of the secondary coolant in the majority of Nuclear Power Plants is controlled by AVT (All Volatile Treatment), wherein volatile amines are used to maintain the alkaline pH required for minimizing the corrosion of structural materials which one of them is Carbon Steel. In this treatment, ammonia, morpholine and ethanolamine are commonly used as conditioning reagents. In this context, experiments were carried out by exposing carbon steel A106 B samples in a simulated secondary coolant in order to study the nature of the oxide films. The tests were performed in a static autoclave at 260°C using two media: I) hydrazine + morpholine and II) hydrazine + ethanolamine during different exposure periods up to ≈1020 h. The oxide film characterization was mainly studied using Scanning Electron Microscopy and X-ray diffraction. A chemical descaling procedure was used to obtain the material weight loss (W) of samples, the adherent and released oxide. The XRD analyses, for all exposures studied, showed that magnetite was the corrosion product formed in the films grown in both media. The material weight loss, after descaling, could be fitted by a law of the type W = ktn, up to 1020 h of exposure tested, resulting in n = 0.42, k = 6.24 for films grown in medium I) and n = 0.39, k = 6.08 for films grown in medium II) respectively (W is in mg/dm2 and t in h). The higher corrosion product release measured in the medium with morpholine could be important in power plant operation.
